Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

Single-cell-specific delivery of small RNAs, such as short hairpin RNA (shRNA) and small noncoding RNAs, allows us to elucidate the roles of specific upregulation of RNA expression and RNAi-mediated gene suppression in early embryo development. The photoinduced cytosolic dispersion of RNA (PCDR) method that we previously reported can introduce small RNAs into the cytosol of photoirradiated cells and enable RNA delivery into a single-cell in a spatiotemporally specific manner. However, the PCDR method has only been applied to planer cultured cells and not to embryos. This study demonstrated that the PCDR method can be utilized for photo-dependent cytosolic shRNA delivery into a single blastomere and for single blastomere-specific RNA interference in mouse embryos. Our results indicate that PCDR is a promising approach for studying the developmental process of early embryogenesis.

DOI： 10.1038/s41598-023-40361-9

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Technologies for visualizing and tracking RNA are essential in molecular biology, including in disease-related fields. In this study, we propose a novel probe set (DAt-probe and T-probe) that simultaneously detects two mutations in the same RNA using fluorescence resonance energy transfer (FRET). The DAt-probe carrying the fluorophore Atto488 and the quencher Dabcyl were used to detect a cancer mutation (exon19del), and the T-probe carrying the fluorophore Tamra was used to detect drug resistance mutations (T790M) in epidermal growth factor receptor (EGFR) mRNA. These probes were designed to induce FRET when both mutations were present in the mRNA. Gel electrophoresis confirmed that the two probes could efficiently bind to the mutant mRNA. We measured the FRET ratios using wild-type and double-mutant RNAs and found a significant difference between them. Even in living cells, the FRET probe could visualize mutant RNA. As a result, we conclude that this probe set provides a method for detecting two mutations in the single EGFR mRNA via FRET.

DOI： 10.1039/d3an00554b

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Japan Society for Laser Surgery and Medicine  

DOI： 10.2530/jslsm.jslsm-44_0004

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Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

BNCT is a non-invasive cancer therapy that allows for cancer cell death without harming adjacent cells. However, the application is limited, owing to the challenges of working with clinically approved boron (B) compounds and drug delivery systems (DDS). To address the issues, we developed self-forming nanoparticles consisting of a biodegradable polymer, namely, "AB-type Lactosome (AB-Lac)" loaded with B compounds. Three carborane isomers (o-, m-, and p-carborane) and three related alkylated derivatives, i.e., 1,2-dimethy-o-carborane (diC1-Carb), 1,2-dihexyl-o-carborane (diC6-Carb), and 1,2-didodecyl-o-carborane (diC12-Carb), were separately loaded. diC6-Carb was highly loaded with AB-Lac particles, and their stability indicated the "molecular glue" effect. The efficiency of in vitro B uptake of diC6-Carb for BNCT was confirmed at non-cytotoxic concentration in several cancer cell lines. In vivo/ex vivo biodistribution studies indicated that the AB-Lac particles were remarkably accumulated within 72 h post-injection in the tumor lesions of mice bearing syngeneic breast cancer (4T1) cells, but the maximum accumulation was reached at 12 h. In ex vivo B biodistribution, the ratios of tumor/normal tissue (T/N) and tumor/blood (T/Bl) of the diC6-Carb-loaded particles remained stably high up to 72 h. Therefore, we propose the diC6-Carb-loaded AB-Lac particles as a promising candidate medicine for BNCT.

Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI  

A connection of a functional peptide with a cell-penetrating peptide (CPP) used a heterodimeric coiled-coil as a molecular zipper can improve the intracellular delivery and activity of the functional peptide. However, the chain length of the coiled coil required for functioning as the molecular zipper is unknown at present. To solve the problem, we prepared an autophagy-inducing peptide (AIP) that conjugates with the CPP via heterodimeric coiled-coils consisting of 1 to 4 repeating units (K/E zipper; AIP-Kn and En-CPP), and we investigated the optimum length of the K/E zipper for effective intracellular delivery and autophagy induction. Fluorescence spectroscopy showed that K/E zippers with n = 3 and 4 formed a stable 1:1 hybrid (AIP-K3/E3-CPP and AIP-K4/E4-CPP, respectively). Both AIP-K3 and AIP-K4 were successfully delivered into cells by the corresponding hybrid formation with K3-CPP and K4-CPP, respectively. Interestingly, autophagy was also induced by the K/E zippers with n = 3 and 4, more intensively by the former than by the latter. The peptides and K/E zippers used in this study did not show significant cytotoxicity. These results indicate that the effective induction of autophagy occurs via an exquisite balance of the association and dissociation of the K/E zipper in this system.

DOI： 10.3390/pharmaceutics15041048

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BNCT is a non-invasive cancer therapy that allows for cancer cell death without harming adjacent cells. However, the application is limited, owing to the challenges of working with clinically approved boron (B) compounds and drug delivery systems (DDS). To address the issues, we developed self-forming nanoparticles consisting of a biodegradable polymer, namely, "AB-type Lactosome (AB-Lac)" loaded with B compounds. Three carborane isomers (o-, m-, and p-carborane) and three related alkylated derivatives, i.e., 1,2-dimethy-o-carborane (diC1-Carb), 1,2-dihexyl-o-carborane (diC6-Carb), and 1,2-didodecyl-o-carborane (diC12-Carb), were separately loaded. diC6-Carb was highly loaded with AB-Lac particles, and their stability indicated the "molecular glue" effect. The efficiency of in vitro B uptake of diC6-Carb for BNCT was confirmed at non-cytotoxic concentration in several cancer cell lines. In vivo/ex vivo biodistribution studies indicated that the AB-Lac particles were remarkably accumulated within 72 h post-injection in the tumor lesions of mice bearing syngeneic breast cancer (4T1) cells, but the maximum accumulation was reached at 12 h. In ex vivo B biodistribution, the ratios of tumor/normal tissue (T/N) and tumor/blood (T/Bl) of the diC6-Carb-loaded particles remained stably high up to 72 h. Therefore, we propose the diC6-Carb-loaded AB-Lac particles as a promising candidate medicine for BNCT.

DOI： 10.3390/cells11203307

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

We developed a method for detecting DNA by excimer fluorescence from two peptide nucleic acids (PNAs) modified with a pyrene (Pyr). The two PNA-Pyr probes were prepared by solid-phase peptide synthesis, and we assessed fluorescence from the mixture of probes with DNA. From the results, excimer fluorescence derived from the two PNA-Pyr probes forming hybrids with the complementary DNA was observed, and the two probes showed the maximum excimer/monomer ratio when the probes and DNA were hybridized at a 1:1:1 ratio, indicating that the PNA-Pyr probes can detect target DNA. Furthermore, we adjusted the spatial arrangement between the two PNA-Pyr hybrids formed on the DNA to promote optimal excimer formation. As a result, optimal excimer formation was achieved by spacing the two nucleobases between the formed two hybrids and further inserting a hexamethylene linker (C6) between the PNA and Pyr of the PNA-Pyr probe on one side.

DOI： 10.1016/j.bmcl.2022.128838

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Tat-U1A-rose bengal conjugate (TatU1A-RB) was prepared as an ultrasound-sensitive RNA carrier molecule. This molecule consists of Tat cell-penetrating peptide, U1A RNA-binding protein, and rose bengal as a sonosensitizer. We demonstrated that TatU1A-RB delivered RNA via the endocytosis pathway, which was followed by ultrasound-dependent endosomal escape and cytosolic dispersion of the RNA. A short hairpin RNA (shRNA) delivered by TatU1A-RB mediated RNA interference (RNAi) ultrasound-dependently. Even by ultrasound irradiation through blood cells, RNAi could be induced with TatU1A-RB and the shRNA. This ultrasound-dependent cytosolic RNA delivery method will serve as the basis for a new approach to nucleic acid therapeutics.

DOI： 10.1016/j.bmcl.2022.128767

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In this study, we performed an elaborate adjustment of the structure of peptide nucleic acid (PNA) molecular beacons as probes for detecting nucleic acids. We synthesized the PNA beacons with various numbers of Glu, Lys, and dabcyl (Dab) quenchers in them, and we investigated their fluorescence changes (F-1/1/F-0) with and without full-match DNA. As the numbers of Glu/Lys or Dab increased, the F-1/1/F-0 tended to decrease. Among the different beacons, the PNA beacon with one Glu and one Lys (P1Q1) showed the largest F-1/1/F-0. On the other hand, a relatively large F-1/1/F-0 was obtained when the number of Glu/Lys and the number of Dab were the same, and the balance between the numbers of Glu/Lys and Dab seemed to affect the F-1/1/F-0. We also investigated the DNA detection by the prehybrid of P1Q1, which consists of the T790M base sequence, [P1Q1(T790M)], with quencher-modified DNA (Q-DNA). We examined the DNA detection with single-base mismatch by P1Q1(T790M), and we clarified that there was difficulty in detecting the sequence with P1Q1 alone, but that the sequence was successfully detected by the prehybrid of P1Q1 with the Q-DNA.

DOI： 10.3390/pr10040722

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Micro RNAs (miRNAs) are involved in a variety of biological functions and are attracting attention as diagnostic and prognostic markers for various diseases. Highly sensitive RNA detection methods are required to determine miRNA expression levels and intracellular localization. In this study, we designed new double-stranded peptide nucleic acid (PNA)/DNA probes consisting of a fluorophore-PNA-quencher (fPq) and a quencher-DNA (qD) for miR-221 detection. We optimized the fPq structure, PNA-DNA hybrid length, and hybrid position. The resultant fPq-2/qD-6b probe was a 6-bp hybrid probe with a 10-base fPq and a 6-base qD. The signal-to-background ratios of the probes showed that fPq-2/qD-6b had a higher target sensitivity than fPq (PNA beacon)-type and fP/qD-type probes. The results of the detection limit and target specificity indicate that the fPq/qD probe is promising for RNA detection in both cells and cell extracts as well as for miRNA diagnosis.

DOI： 10.1016/j.bmcl.2021.128359

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PORTFOLIO  

Methods to spatially induce apoptosis are useful for cancer therapy. To control the induction of apoptosis, methods using light, such as photochemical internalization (PCI), have been developed. We hypothesized that photoinduced delivery of microRNAs (miRNAs) that regulate apoptosis could spatially induce apoptosis. In this study, we identified pre-miR-664a as a novel apoptosis-inducing miRNA via mitochondrial apoptotic pathway. Further, we demonstrated the utility of photoinduced cytosolic dispersion of RNA (PCDR), which is an intracellular RNA delivery method based on PCI. Indeed, apoptosis is spatially regulated by pre-miR-664a and PCDR. In addition, we found that apoptosis induced by pre-miR-664a delivered by PCDR was more rapid than that by lipofection. These results suggest that pre-miR-664a is a nucleic acid drug candidate for cancer therapy and PCDR and pre-miR-664a-based strategies have potential therapeutic uses for diseases affecting various cell types.

DOI： 10.1038/s41598-021-94249-7.

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE INC  

The A3B-type Lactosome comprised of poly(sarcosine)3-block-poly(l-lactic acid), a biocompatible and biodegradable polymeric nanomicelle, was reported to accumulate in tumors in vivo via the enhanced permeability and retention (EPR) effect. Recently, the cellular uptake of Lactosome particles was enhanced through the incorporation of a cell-penetrating peptide (CPP), L7EB1. However, the ability of Lactosome as a drug delivery carrier has not been established. Herein, we have developed a method to conjugate the A3B-type Lactosome with ATP-binding cassette transporter G2 (ABCG2) siRNA for inducing in vitro apoptosis in the cancer cell lines PANC-1 and NCI-H226. The L7EB1 peptide facilitates the cellular uptake efficiency of Lactosome but does not deliver siRNA into cytosol. To establish the photoinduced cytosolic dispersion of siRNA, a photosensitizer loaded L7EB1-Lactosome was prepared, and the photosensitizer 5,10,15,20-tetra-kis(pentafluorophenyl)porphyrin (TPFPP) showed superiority in photoinduced cytosolic dispersion. We exploited the combined effects of enhanced cellular uptake by L7EB1 and photoinduced endosomal escape by TPFPP to efficiently deliver ABCG2 siRNA into the cytosol for gene silencing. Moreover, the silencing of ABCG2, a protoporphyrin IX (PpIX) transporter, also mediated photoinduced cell death via 5-aminolevulinic acid (ALA)-mediated PpIX accumulated photodynamic therapy (PDT). The synergistic capability of the L7EB1/TPFPP/siRNA-Lactosome complex enabled both gene silencing and PDT.

DOI： 10.1016/j.xphs.2021.01.026

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Language：English   Publisher：MDPI  

DOI： 10.3390/app11083594

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Pro-apoptotic peptides may be promising agents for cancer therapy owing to their ability to induce apoptosis in cancer cells. TatBim, a fusion peptide of Tat cell-penetrating peptide (CPP) and the BH3 domain derived from Bim apoptosis-inducing protein, is a pro-apoptotic peptide. In this study, based on the TatBim sequence, we attempted to minimize the CPP-Bim peptide while retaining apoptosis-inducing activity. The CPP and Bim parts were systematically shortened, and the pro-apoptotic activities of the shortened peptides were examined. We obtained TatBim-N1C2 and R8Bim-N1C2 as minimized peptides with efficient apoptotic activity. These peptides may have potential applications in future biomedical studies, such as cancer therapeutics.

DOI： 10.1016/j.bmcl.2021.127811

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DOI： 10.3390/ijms22094982.

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"Theranostics," a new concept of medical advances featuring a fusion of therapeutic and diagnostic systems, provides promising prospects in personalized medicine, especially cancer. The theranostics system comprises a novel 89Zr-labeled drug delivery system (DDS), derived from the novel biodegradable polymeric micelle, "Lactosome" nanoparticles conjugated with specific shortened IgG variant, and aims to successfully deliver therapeutically effective molecules, such as the apoptosis-inducing small interfering RNA (siRNA) intracellularly while offering simultaneous tumor visualization via PET imaging. A 27 kDa-human single chain variable fragment (scFv) of IgG to establish clinically applicable PET imaging and theranostics in cancer medicine was fabricated to target mesothelin (MSLN), a 40 kDa-differentiation-related cell surface glycoprotein antigen, which is frequently and highly expressed by malignant tumors. This system coupled with the cell penetrating peptide (CPP)-modified and photosensitizer (e.g., 5, 10, 15, 20-tetrakis (4-aminophenyl) porphyrin (TPP))-loaded Lactosome particles for photochemical internalized (PCI) driven intracellular siRNA delivery and the combination of 5-aminolevulinic acid (ALA) photodynamic therapy (PDT) offers a promising nano-theranostic-based cancer therapy via its targeted apoptosis-inducing feature. This review focuses on the combined advances in nanotechnology and material sciences utilizing the "89Zr-labeled CPP and TPP-loaded Lactosome particles" and future directions based on important milestones and recent developments in this platform.

DOI： 10.3390/life11020158

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A heterodimeric leucine zipper composed of a pair of leucine zipper peptides containing acidic or basic amino acid residues at appropriate positions in each peptide was used as a molecular glue to connect protein cargos to a cell-penetrating peptide (CPP) carrier. To investigate the hybridization properties by fluorescence experiments, we prepared an enhanced green fluorescent protein (EGFP) fused with an acidic leucine zipper (LzK), EGFP-LzK, and a basic leucine zipper (LzE) modified with a CPP, LzE-CPP. The LzK and LzE formed a 1:1 hybrid when EGFP-LzK and LzE-CPP were mixed in phosphate buffer saline, thereby conjugating the EGFP with the CPP. The formation of the 1:1 hybrid was confirmed by fluorescence spectra and fluorescence titration curves. Results from fluorescence microscopy experiments showed that EGFP was successfully delivered into cells by conjugating with the CPP via formation of the LzK/LzE hybrid. We also fused the apoptotic protein p53 with LzK (p53-LzK) and investigated the inhibition of cell proliferation of various cell lines by incubation with the p53-LzK/LzE-CPP hybrid. This hybrid was found to localize in nuclei and successfully inhibited cell-specific proliferation. The LzE/LzK zipper system inhibited cell proliferation more efficiently than the directly fused conjugate, p53-CPP. Our method will be a useful drug delivery system for delivering bioactive proteins to treat various diseases.

DOI： 10.1016/j.bmc.2021.116036

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

<p>To investigate RNA degradation in live cells, detection methods that do not require RNA extraction from cells are necessary. In this study, we examined the utility of fluorescence lifetime measurements...</p>

DOI： 10.1039/d0an01230k

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Endosomal escape in cell-penetrating peptide (CPP)-based drug/macromolecule delivery systems is frequently insufficient. The CPP-fused molecules tend to remain trapped inside endosomes and end up being degraded rather than delivered into the cytosol. One of the methods for endosomal escape of CPP-fused molecules is photochemical internalization (PCI), which is based on the use of light and a photosensitizer and relies on photoinduced endosomal membrane destabilization to release the cargo molecule. Currently, it remains unclear how this delivery strategy behaves after photostimulation. Recent findings, including our studies using CPP-cargo-photosensitizer conjugates, have shed light on the photoinduced endosomal escape mechanism. In this review, we discuss the structural design of CPP-photosensitizer and CPP-cargo-photosensitizer conjugates, and the PCI mechanism underlying their application.

DOI： 10.3390/molecules26010036

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE RESEARCH  

Investigation of the relevance between cell cycle status and the bioactivity of exogenously delivered biomacromolecules is hindered by their time-consuming cell internalization and the cytotoxicity of transfection methods. In this study, we addressed these problems by utilizing the photochemical internalization (PCI) method using a peptide/protein-photosensitizer conjugate, which enables immediate cytoplasmic internalization of the bioactive peptides/proteins in a light-dependent manner with low cytotoxicity. To identify the cell-cycle dependent apoptosis, a TatBim peptide-photosensitizer conjugate (TatBim-PS) with apoptotic activity was photo-dependently internalized into HeLa cells expressing a fluorescent ubiquitination-based cell cycle indicator (Fucci2). Upon irradiation, cytoplasmic TatBim-PS internalization exceeded 95% for all cells classified in the G1, S, and G2/M cell cycle phases with no significant differences between groups. TatBim-PS-mediated apoptosis was more efficiently triggered by photoirradiation in the G1/S transition than in the G1 and S/G2/M phases, suggesting high sensitivity of the former phase to Bim-induced apoptosis. Thus, the cell cycle dependence of Bim peptide-induced apoptosis was successfully investigated using Fucci2 indicator and the PCI method. Since PCI-mediated cytoplasmic internalization of peptides is rapid and does not span multiple cell cycle phases, the Fucci-PCI method constitutes a promising tool for analyzing the cell cycle dependence of peptides/protein functions.

DOI： 10.1038/s41598-020-76100-7

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Research into cancer cells that harbor gene mutations relating to anticancer drug-resistance at the single-cell level has focused on the diagnosis of, or treatment for, cancer. Several methods have been reported for detecting gene-mutated cells within a large number of non-mutated cells; however, target single nucleotide-mutated cells within a large number of cell samples, such as cancer tissue, are still difficult to analyze. In this study, a new system is developed to detect and isolate single-cancer cells expressing the T790M-mutated epidermal growth factor receptor (EGFR) mRNA from multiple non-mutated cancer cells by combining single-cell microarray chips and peptide nucleic acid (PNA)-DNA probes. The single-cell microarray chip is made of polystyrene with 62,410 microchambers (31-40 µm diameter). The T790M-mutated lung cancer cell line, NCI-H1975, and non-mutated lung cancer cell line, A549, were successfully separated into single cells in each microchambers on the chip. Only NCI-H1975 cell was stained on the chip with a fluorescein isothiocyanate (FITC)-conjugated PNA probe for specifically detecting T790M mutation. Of the NCI-H1975 cells that spiked into A549 cells, 0-20% were quantitatively analyzed within 1 h, depending on the spike concentration. Therefore, our system could be useful in analyzing cancer tissue that contains a few anticancer drug-resistant cells.

DOI： 10.3390/mi11070628

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Cell-penetrating peptides (CPPs) are widely used for the intracellular delivery of peptides and proteins, but CPP fusion peptides and proteins are often transported by endocytosis and trapped in endosomes. Photochemical internalization (PCI) is a method for the endosomal escape of the trapped peptide or protein and release into the cytosol using light and photosensitizers. In PCI, endosomal membranes are thought to be destabilized by singlet oxygen (1O2) photogenerated from photosensitizers localized in endosomes. We previously developed CPP-cargo-photosensitizer (PS) conjugates able to photodependently enter the cytosol via the PCI mechanism. For example, TatU1A-PS (a covalent complex of Tat [CPP], U1A RNA-binding protein [cargo], and PS) can photodependently deliver RNAs into the cytosol, and TatBim-PS (a covalent complex of Tat, Bim [cargo], and PS) can photoinduce apoptosis in mammalian cells. However, for many newly created conjugates, the induction of PCI has been insufficient. We hypothesized that the amino acid linker sequence (XX) adjacent to the photosensitizer is an important determinant of PCI efficiency. In this study, using CPP-cargo-XX-PS platforms, we examined the relationship between PCI efficiency and the linker amino acid sequence near the photosensitizer. We found that hydrophobic FF and LL linkers enhanced the PCI efficiencies of both TatBim-XX-PS and TatU1A-XX-PS. The effectiveness of the linker depended, in part, on both the cargo moiety and the photosensitizer. These results may guide the design of CPP-cargo-PS conjugates conferring broad target functions for PCI and photodynamic therapy.

DOI： 10.1021/acs.bioconjchem.0c00046

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Development of an intracellular delivery method for functional peptides via cell-penetrating peptides (CPPs) expands peptide use in basic research and therapeutic applications. Although direct conjugation of a functional peptide with a CPP is the simplest method for delivery, this method has not always been reliable. CPPs usually contain several positively charged amino acids that potentially interact non-specifically with negatively charged molecules in cells and subsequently interfere with conjugated functional peptide function. Here we demonstrate a new intracellular delivery method for peptides in which a functional peptide is released from a positively charged CPP via peptide nucleic acids (PNAs). We prepared an 8-mer PNA conjugated to octa-arginine in tandem (PNA1-CPP) and linked its complementary PNA to an autophagy inducing peptide (PNA2-AIP) by solid-phase peptide synthesis. PNA1-CPP and PNA2-AIP formed a 1 : 1 hybrid via PNA1/PNA2 interaction, thereby indirectly but stably connecting the AIP to the CPP. PNA2-AIP was successfully delivered into cells in a hybrid formation-dependent manner and at least some portion of the PNA1-CPP/PNA2-AIP hybrids dissociated into PNA2-AIP and PNA1-CPP inside the cells. Notably, PNA2-AIP delivered to cells induced more autophagy than AIP directly conjugated to CPP (CPP-AIP). Further, the PNA hybrid did not induce significant cell death. These findings indicate that the PNA1/PNA2 hybrid can function as a molecular glue enabling the delivery of functional peptides into cells.

DOI： 10.1039/c9ob02559f

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The inefficient endosomal escape of drugs or macromolecules is a major obstacle to achieving successful delivery to therapeutic targets. An efficient approach to circumvent this barrier is photochemical internalization (PCI), which uses light and photosensitizers for endosomal escape of the delivered macromolecules. The PCI mechanism is related to photogenerated singlet oxygen, but the mechanism is still unclear. In this study, we examined the relation of PCI to heat, pH and Ca2+ ions using cell penetrating peptide (CPP)-cargo-photosensitizer (Alexa546 or Alexa633) conjugates. A cell temperature changing experiment demonstrated that heat (thermal mechanism) does not significantly contribute to the photoinduced endosomal escape. Inhibition of V-ATPase proton pump activity and endosomal pH upregulation indicated that PCI-mediated endosomal escape needs endosomal acidification prior to photoirradiation. Imaging of the CPP-cargo-photosensitizer and Ca2+ ions during photostimulation showed that intracellular calcium increase is not the cause of the endosomal escape of the complex. The increment is mainly due to Ca2+ influx. These findings show the importance of extra- and intracellular milieu conditions in the PCI mechanism and enrich our understanding of PCI-related changes in cell.

DOI： 10.1111/php.13146

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Lung cancer cells harbor various gene mutations in the mRNA sequence of the Epidermal Growth Factor Receptor (EGFR), especially the mutations of exon19del E746-A750, T790M, and L858R. This results in cancer progression and resistance to anticancer drugs (tyrosine kinase inhibitor; TKI). Therefore, the imaging analysis of EGFR mutations is required for the treatment planning for non-small cell lung cancers. This study focused on the imaging analysis of a single nucleotide substitute in EGFR mutated cancer cells. We developed three novel peptide nucleic acid (PNA)-DNA probes for recognizing and detecting the following three gene mutations in EGFR gene mutations. The PNA-DNA probes consist of fluorescein isothiocyanate (FITC) conjugated PNA as a detection probe and Dabcyl conjugated DNA as a quencher probe. The PNA-DNA probes were used to validate the feasibility for detecting three EGFR mutated sequences: exon19del E746-A750, T790M, and L858R. The three probes emitted fluorescent dose-dependent signals against three target DNA and RNA. Using the three PNA-DNA probes, we succeeded in distinguishing three kinds of lung-cancer cell lines (H1975, PC-9, and A549) which have different EGFR mutations by the fluorescence in situ hybridization (FISH) method.

DOI： 10.1039/c9an00725c

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We synthesized a pair of compounds containing leucine zipper peptides to deliver protein cargo into cells. One is a cell-penetrating peptide (CPP) with Lz(E), a leucine zipper peptide containing negatively charged amino acids, and the other is a Nanog protein with Lz(K), a leucine zipper peptide containing positively charged amino acids. When cells were treated with these equimolar mixtures, Nanog-Lz(K) hybridized with Lz(E)-CPP was successfully delivered into the cells. Furthermore, Nanog-Lz(K) exerted its proper function after nuclear transport.

DOI： 10.1016/j.bmcl.2019.02.004

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The present study investigated combined biological effects of peptide and miRNA in a peptide/miRNA nanocomplex. We utilized TatBim peptide as a cell-penetrating peptide-based RNA carrier with apoptotic activity. miRNA with apoptotic activity (miR-34a) was used for complex formation to investigate the additional effects of the combination with TatBim peptide. TatBim peptide and the miRNA formed nanocomplexes (approximately 250 nm in diameter), and these complexes were efficiently internalized by cells. Despite its efficient cell internalization, apoptotic activity of the nanocomplex decreased with increasing RNA content. However, photosensitizer-attachment to TatBim and photo irradiation significantly improved the apoptotic activity of the nanocomplex by facilitating dispersion of the peptide and RNA in the cytoplasm. Combined apoptotic activity of both TatBim peptide and miR-34a in the nanocomplex was demonstrated by substituting TatBim with Lipofectamine and by substituting miR-34a with scrambled siRNA. (C) 2019, The Society for Biotechnology, Japan. All rights reserved.

DOI： 10.1016/j.jbiosc.2019.01.003

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Cellular functions are regulated by the up- and down-regulation and localization of RNA molecules. Therefore, many RNA detection methods have been developed to analyze RNA levels and localization. Molecular beacon (MB) is one of the major methods for quantitative RNA detection and analysis of RNA localization. Most oligonucleotide-based probes, including MB, are designed to target a long flexible region on the target RNA molecule, e.g., a single-stranded region. Recently, analyses of tRNA localization and levels became important, as it has been shown that environmental stresses and chemical reagents induce nuclear accumulation of tRNA and tRNA degradation in mammalian cells. However, tRNA is highly structured and does not harbor any long flexible regions. Hence, only a few methods are currently available for detecting tRNA. In the present study, we attempted to detect elongator tRNAMet (eMet) and initiator tRNAMet (iMet) by using an in-stem molecular beacon (ISMB), characterized by more effective quenching and significantly higher sensitivity than those of conventional MB. We found that ISMB1 targeted a 5'- region that includes the D arm of tRNA and that it detected eMet and iMet transcripts as well as mature eMet with high sensitivity. Moreover, the analysis revealed that the formation of the ISMB/tRNA transcript complex required more time than the formation of an ISMB/unstructured short RNA complex. These results suggest that ISMB-based tRNA detection can be a useful tool for various biological and medical studies.

DOI： 10.1371/journal.pone.0211505

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Many cellular events are thought to be controlled by the temporal upregulation of multiple RNAs; the timing of the upregulation of these RNAs is not always the same. In this study, we first show that our light-directed intracellular RNA delivery method induced high concentrations of RNA in a short period. This effect was beneficial for the temporal control of cellular events by functional RNAs. Next, we stimulated the short-term upregulation of two different RNAs at different time points. Cytosolic delivery of a first RNA was induced by red light; thereafter, cytosolic delivery of a second RNA was induced by near-infrared light. The time difference between the introduction of the first and second RNA can be short (0.5-4 h) or long (>8 h). This strategy shows the potential for future applications of the deliberate control of time-dependent RNA concentration to guide various cellular functions by multiple RNAs.

DOI： 10.1021/acs.bioconjchem.8b00487

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Blackwell Publishing Ltd  

MicroRNAs (miRNAs) belong to a class of small noncoding RNAs that play important roles in the translational regulation of gene expression. A number of miRNAs are known to act as key regulators of diverse processes such as neuronal differentiation. In this study, we have attempted to identify novel miRNAs related to neuronal differentiation via microarray analysis in the human neuronal differentiation model neuroblastoma SH-SY5Y cells. We identified 15 up-regulated and eight down-regulated miRNAs in SH-SY5Y cells treated with all-trans retinoic acid to induce differentiation. We further showed that one of the up-regulated miRNAs, miR-664a-5p, promoted neuronal differentiation of SH-SY5Y cells. These findings enhance our understanding of the miRNAs involved in the process of neurogenesis and, in particular, highlight an important role of miR-664a-5p in SH-SY5Y cell neuronal differentiation. Further studies will be required to confirm the function of miR-664-5p in neuronal development and disease and to identify its relevant target genes.

DOI： 10.1111/gtc.12559

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier Ltd  

Multivalent cell-penetrating peptides (CPPs) have been reported to show enhancement in cellular uptake and endosomolytic activity. However, its application was limited to trans-delivery of cargo which is lower in cellular uptake efficiency of cargo than cis-delivery. Here, we tried the cis-delivery of cargo with multivalent CPP by preparing bioreducible dimeric CPP–cargo with apoptotic activity using TatBim peptide, a fusion of Tat CPP and Bim peptide derived from Bim apoptosis-inducing protein. Dimeric TatBim was almost twice as highly internalized by cells and significantly induced apoptosis compared to monomeric TatBim. Contribution of bioreducible linkage of dimeric TatBim towards apoptotic activity was also confirmed.

DOI： 10.1016/j.bmcl.2017.12.035

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A method to induce cytoplasmic peptide delivery, using ultrasound, was demonstrated using a molecular conjugate of a cell-penetrating peptide (CPP), a functional peptide, and a sonosensitizer. As a model of such molecular conjugates, TatBim-RB, consisting of the Tat CPP, the Bim apoptosis inducing peptide, and the sonosensitizer rose bengal was synthesized. CPPs have been widely used for intracellular delivery of various cargos; however, CPP-fused molecules tend to become entrapped in endosomes, as was observed for TatBim-RB molecules applied to cells. To promote escape of the entrapped TatBim-RB molecules, cells were irradiated with ultrasound, which successfully induced endosomal escape and cytoplasmic dispersion of TatBim-RB, and subsequently apoptosis. Our results suggest that this peptidesonosensitizer conjugate strategy may facilitate numerous kinds of medicinal chemistry studies, and furthermore, this specific conjugate may exhibit potential as a novel therapeutic agent for the promotion of apoptosis. (C) 2017 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmc.2017.06.024

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

The use of molecular beacons is a versatile method to detect RNAs. Typically, a single-stranded region of RNA is selected as a target sequence for molecular beacons. Therefore, the detection of highly structured short RNAs, such as tRNAs, seems to be difficult. In this study, as an example of highly structured target RNA, we used human tRNA(Lys3), which is known to have functions in protein synthesis and the reverse transcription of human immunodeficiency virus (HIV)-1. No long single-stranded region more than 8 nt is present in this tRNA, which is much shorter than the standard target length of molecular beacons (similar to 20 nt). This study showed that sensitive detection of highly structured RNAs using molecular beacons was much more difficult than that of unstructured or less structured RNAs. However, efficient detection of the tRNA(Lys3) was achieved by selecting the best target region, i.e., the region around the D arm, probably due to the ease of unfolding of this arm. Accordingly, our findings suggested that molecular beacons may have applications in the detection of highly structured RNAs related to various biological functions and diseases.

DOI： 10.1039/c7ay00341b

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PORTLAND PRESS LTD  

Translation elongation factor Tu (EF-Tu) delivers aminoacyl-tRNA (aa-tRNA) to ribosomes in protein synthesis. EF-Tu generally recognizes aminoacyl moieties and acceptor-and T-stems of aa-tRNAs. However, nematode mitochondrial (mt) tRNAs frequently lack all or part of the T-arm that is recognized by canonical EF-Tu. We previously reported that two distinct EF-Tu species, EF-Tu1 and EF-Tu2, respectively, recognize mt tRNAs lacking T-arms and D-arms in the mitochondria of the chromadorean nematode Caenorhabditis elegans. C. elegans EF-Tu2 specifically recognizes the seryl moiety of serylated D-armless tRNAs. Mitochondria of the enoplean nematode Trichinella possess three structural types of tRNAs: T-armless tRNAs, D-armless tRNAs, and cloverleaf tRNAs with a short T-arm. Trichinella mt EF-Tu1 binds to all three types and EF-Tu2 binds only to D-armless Ser-tRNAs, showing an evolutionary intermediate state from canonical EF-Tu to chromadorean nematode (e. g. C. elegans) EF-Tu species. We report here that two EF-Tu species also participate in Drosophila melanogaster mitochondria. Both D. melanogaster EF-Tu1 and EF-Tu2 bound to cloverleaf and D-armless tRNAs. D. melanogaster EF-Tu1 has the ability to recognize T-armless tRNAs that do not evidently exist in D. melanogaster mitochondria, but do exist in related arthropod species. In addition, D. melanogaster EF-Tu2 preferentially bound to aatRNAs carrying small amino acids, but not to aa-tRNAs carrying bulky amino acids. These results suggest that the Drosophila mt translation system could be another intermediate state between the canonical and nematode mitochondria-type translation systems.

DOI： 10.1042/BCJ20160929

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

The possibility of spatiotemporally photocontrolling translation holds considerable promise for studies on the biological roles of local translation in cells and tissues. Here we report caged aminoacyl-tRNAs (aa-tRNAs) synthesized using a (7-diethylaminocoumarin-4-yl) methoxycarbonyl (DEACM)-cage compound. DEACM-caged aa-tRNA does not spontaneously deacylate for at least 4 h in neutral aqueous solution, and does not bind to the elongation factor Tu. On irradiation at similar to 405 nm at 125mWcm(-2), DEACM-aa-tRNA is converted into active aa-tRNA with a half-life of 19 s. Notably, this rapid uncaging induced by visible light does not impair the translation system. Translation is photoinduced when DEACM-aa-tRNA carrying a CCCG or a CUA anticodon is uncaged in the presence of mRNAs harbouring a CGGG four-base codon or a UAG amber codon, respectively. Protein synthesis is phototriggered in several model systems, including an in vitro translation system, an agarose gel, in liposomes and in mammalian cells.

DOI： 10.1038/ncomms12501

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A novel molecule, TatBim-Alexa, consisting of the HIV1 Tat cell-penetrating peptide, the Bim apoptosis-inducing peptide, and Alexa Fluor 546 was synthesized for photoinducion of apoptosis. The Alexa Fluor 546 was used as a photosensitizer and covalently attached at the C-terminus of TatBim peptide by the thiol-maleimide reaction. Photo-dependent cytosolic internalization of TatBim-Alexa and photo-dependent apoptosis using TatBim-Alexa were demonstrated in several kinds of mammalian cells including human cancer cell lines. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2016.04.091

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Polymeric micelles that are composed of synthetic polymers are generally size controllable and can be easily modified for various applications. Lactosomes (A3B-type) are biodegradable polymeric micelles composed of an amphipathic polymer, including three poly(sarcosine) blocks and a poly(l-lactic acid) block. Lactosomes accumulate in tumors in vivo through the enhanced permeability and retention (EPR) effect, even on frequently administering them. However, lactosomes cannot be efficiently internalized by cells. To improve cellular uptake of lactosomes, cell-penetrating peptide (CPP)-modified lactosomes were prepared. Seven CPPs (including EB1 and Pep1) were used, and most of them improved the cellular uptake efficiency of lactosomes. In particular, EB1- and Pep1-modified lactosomes were efficiently internalized by cells. In addition, by using CPP-modified and photosensitizer-loaded lactosomes, we demonstrated the photoinduced killing of mammalian cells, including human cancer cells. Accumulation of the EB1-modified lactosomes in NCI-N87 tumors was shown by in vivo imaging. Thus, this study demonstrated that the CPP-modified lactosome is a promising drug carrier.

DOI： 10.1080/14686996.2016.1178056

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER ACADEMIC PRESS INC  

Small interfering RNA (siRNA) and short hairpin RNA (shRNA) may potentially treat a wide variety of diseases through RNA interference-mediated silencing of specific genes. MicroRNAs (miRNAs) are endogenous regulatory RNA molecules that also modulate gene expression, and thus potential therapeutic approaches using miRNAs have attracted attention. For clinical application of these small RNAs, efficient and safe RNA delivery to target tissues and cells is necessary. Current challenges to RNA delivery are the penetration of negatively charged RNAs through the cell membrane and specific delivery of RNA into target cells. Photocontrolled intracellular RNA delivery is a promising strategy with high target specificity. This strategy includes photodependent endosomal escape of RNA or photodependent release of RNAs from carrier particles. In this chapter, photocontrolled intracellular RNA delivery methods employing gold or silver nanoparticles, upconversion nanoparticles, proteins, or polymers are discussed.

DOI： 10.1016/bs.pmbts.2015.10.013

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

In many drug delivery strategies, an inefficient transfer of macromolecules such as proteins and nucleic acids to the cytosol often occurs because of their endosomal entrapment. One of the methods to overcome this problem is photochemical internalization, which is achieved using a photosensitizer and light to facilitate the endosomal escape of the macromolecule. In this study, we examined the molecular mechanism of photochemical internalization of cell penetrating peptide-cargo (macromolecule)-photosensitizer conjugates. We measured the photophysical properties of eight dyes (photosensitizer candidates) and determined the respective endosomal escape efficiencies using these dyes. Correlation plots between these factors indicated that the photogenerated O-1(2) molecules from photosensitizers were highly related to the endosomal escape efficiencies. The contribution of O-1(2) was confirmed using O-1(2) quenchers. In addition, time-lapse fluorescence imaging showed that the photoinduced endosomal escape occurred at a few seconds to a few minutes after irradiation (much longer than O-1(2) lifetime), and that the pH increased in the endosome prior to the endosomal escape of the macromolecule.

DOI： 10.1038/srep18577

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Translation systems with four-base codons provide a powerful strategy for protein engineering and protein studies because they enable site-specific incorporation of non-natural amino acids into proteins. In this study, a caged aminoacyl-tRNA with a four-base anticodon was synthesized. The caged aminoacyl-tRNA contains a photocleavable nitroveratryloxycarbonyl (NVOC) group. This study showed that the caged aminoacyl-tRNA was not deacylated, did not bind to EF-Tu, and was activated by light. Photo-dependent translation of an mRNA containing the four-base codon was demonstrated using the caged aminoacyl-tRNA. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2014.10.053

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Stress induces various responses, including translational suppression and tRNA degradation in mammals. Previously, we showed that heat stress induces degradation of initiator tRNA(Met) (iMet) through 5'-3' exoribonuclease Xrn1 and Xrn2, respectively. In addition, we found that rapamycin inhibits the degradation of iMet under heat stress conditions. Here, we report that the mammalian target of rapamycin (mTOR) regulates the diffusion of Xrn2 from the nucleolus to the nucleoplasm, facilitating the degradation of iMet under conditions of heat stress. Our results suggest a mechanism of translational suppression through mTOR-regulated iMet degradation in mammalian cells. (C) 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.febslet.2014.08.003

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Authorship：Last author,　Corresponding author   Language：English   Publisher：FRONTIERS MEDIA SA  

Conventional tRNAs have highly conserved sequences, four-armed cloverleaf secondary structures, and L-shaped tertiary structures. However, metazoan mitochondrial tRNAs contain several exceptional structures. Almost all tRNA(Ser) for AGY/N codons lack the D-arm. Furthermore, in some nematodes, no four-armed cloverleaf-type tRNAs are present: two tRNAs(Ser) without the D-arm and 20 tRNAs without the T-arm are found. Previously, we showed that in nematode mitochondria, an extra elongation factor Tu (EF-Tu) has evolved to support interaction with tRNAs lacking the T-arm, which interact with C-terminal domain 3 in conventional EF-Tu. Recent mitochondrial genome analyses have suggested that in metazoan lineages other than nematodes, tRNAs without the T-arm are present. Furthermore, even more simplified tRNAs are predicted in some lineages. In this review, we discuss mitochondrial tRNAs with divergent structures, as well as protein factors, including EF-Tu, that support the function of truncated metazoan mitochondrial tRNAs.

DOI： 10.3389/fgene.2014.00109

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Publishing type：Part of collection (book)   Publisher：Springer Netherlands  

DOI： 10.1007/978-94-017-8896-0_19

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Controlled activation of small RNAs, such as small interfering RNA, in cells is very useful for various biological applications. Light is an effective inducer of controlled activation
in particular, near-infrared light is favorable because it can penetrate deeper into tissues than UV or visible light. In this study, near-infrared light control of RNA interference (RNAi) was demonstrated in mammalian cells using a photosensitive RNA carrier molecule, consisting of an RNA carrier protein and a fluorochrome. The photosensitive carrier molecule was identified from six candidates, each with a different fluorochrome. Using this carrier molecule, cytosolic RNA delivery and RNAi can be triggered by near-infrared light. Cytotoxicity was not observed after photoinduction of RNAi. © 2013 American Chemical Society.

DOI： 10.1021/bc4001195

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

In this report, we describe dendritic peptides possessing central fluorescent amino acids with adjacent branched amino acids. These fluorescent-peptide dendrimers were prepared using (9-fluorenyl)methoxycarbonyl (Fmoc)-based solid-phase peptide synthesis and Fmoc-derivative fluorescent and branched amino acids. The branched amino acids featured multiple carboxylic acids in their side chains, making the fluorescent-peptide dendrimers highly water-soluble compared with the analogous peptides containing the fluorescent amino acids only. The branched amino acid units also improved the fluorescence intensity of the dendrimers. Based on high-pressure liquid chromatography and fluorescence spectroscopy results, we determined that the fluorescent groups were located in the core and that the carboxylic acids were located on the surface of the dendrimers. Fluorescence resonance energy transfer was achieved among the three proximal fluorescent groups in one of the fabricated fluorescent-peptide dendrimers. (C) 2012 Wiley Periodicals, Inc.

DOI： 10.1002/bip.22175

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Authorship：Last author,　Corresponding author   Language：English   Publisher：AMER CHEMICAL SOC  

Because RNA interference (RNAi) can be applied to any gene, this technique has been widely used for studying gene functions. In addition, many researchers are attempting to use RNAi technology in RNAi-based therapies. However, several challenging and controversial issues have arisen during the widespread application of RNAi including target gene specificity, target cell specificity, and spatiotemporal control of gene silencing. To address these issues, several groups have utilized photochemistry to control the RNA release, both spatially and temporally.
In this Account, we foam on recent studies using photocleavable protecting groups, photosensitizes, Hand gold nanoparticles for photoinduced RNAi. In 2005 the first report of photoinduced RNAi used a caged short interfering RNA (siRNA), an siRNA carrying a photocleavable protecting group. Caging groups block the bioactivities of target molecules, but allow for complete recovery of these functions via photoactivation. However, some RNAi activity can occur in these caged siRNAs, so it will be necessary to decrease this "leakage" and raise the RNAi activity restored after irradiation. This technique also uses UV light around 350 nm, which is cytotoxic, but in the near future we expect that it will be possible to use visible and near-infrared light
We also examine the application of photochemical internalization (PCI) to RNAi technology, which involves a combination of photosensitizers and light Instead of inducing RNAi using light, the strategy behind this method was to enhance RNAi using RNA carriers. Many wellknown RNA carriers deliver siRNAs into cells by endocytosis. The siRNAs are trapped in endocytic vesicles and have to be released into the cytoplasm in order to express their activity. To achieve the endosomal escape of siRNAs, PCI technology employed photosensitizers to generate light-dependent reactive oxygen species (ROS) that disrupted the endocytic vesicles. In most studies, RNAi-mediated knockdown of the target gene was detected even without PCI. Recently, a polymer capable of trapping the siRNA in endocytic vesicles controlled RNAi almost entirely by light. CLIP-RNAi uses photosensitizing carrier proteins that can be activated over a wide range of visible light wavelengths. With this method RNA carrier/siRNA complexes are completely trapped within endosomes, and RNAi is controlled strictly by light. Such precise, light-dependent control will open up new possibilities for cellular and molecular biology and therapy.
Most recently, gold nanoparticles (AuNPs) conjugated to siRNA have provided temporal and spatial control of RNAL The light-dependent melting of AuNPs accompanied by a shape transformation induces the release of thiolated siRNAs from AuNPs. In this method, the unique optical properties of the AuNP enable deep penetration of the excitation light into tissues at nearinfrared wavelengths.
The development of photoinduced RNAi technology will lead to novel insights into gene functions and selective drug delivery, and many other scientific fields will continue to influence its progress.

DOI： 10.1021/ar200227n

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

The integral membrane protein bacteriorhodopsin, containing a fluorescent amino acid at a specific position, was synthesized in the presence of hydrated lipid films using an in vitro translation system expanded with a four-base codon/anticodon pair. Cell-sized liposomes with the labeled protein inserted into the liposome membranes were generated after the translation reaction. This study also demonstrated that this labeling method could be used to analyze the dynamic properties of membrane proteins in situ by fluorescence correlation spectroscopy. (C) 2011 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.ab.2011.06.026

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

RNA interference (RNAi) is being widely explored as a tool in functional genomics and tissue engineering, and in the therapy of intractable diseases, including cancer and neurodegenerative diseases. Recently, we developed a photoinducible RNAi method using photosensitizing carrier proteins, named CLIP-RNAi (CPP-linked REP-mediated RNA internalization and photoinduced RNAi). Novel carrier proteins were designed for this study to establish a highly efficient delivery system for small interfering RNA (siRNA) or short hairpin RNA (shRNA) and to demonstrate light-dependent gene silencing. In addition, the results suggested that the dissociation of the siRNA (or shRNA) from carrier proteins in the cytoplasm is a critical event in CLIP-RNAi-mediated gene silencing.

DOI： 10.1021/bc200095a

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Arginine analogs were incorporated site-specifically into proteins using an in vitro translation system. In this system, mRNAs containing a CGGG codon were translated by an aminoacyl-tRNA(CCCG), which was charged with arginine analogs using yeast arginyl-tRNA synthetase. N(G)-monomethyl-L-arginine, L-citrulline and L-homoarginine were incorporated successfully into proteins using this method. The influence of arginine monomethylation in histone H3 on the acetylation of lysine residues by histone acetyltransferase hGCN5 was investigated, and the results demonstrated that K9 acetylation was suppressed by the methylation of R8 and R17 but not by R26 methylation. K18 acetylation was not affected by the methylation of R8. R17 and R26. This site-specific modification strategy provides a way to explore the roles of post-translational modifications in the absence of heterogeneity due to other modifications. (C) 2011 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2011.09.137

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

To investigate the antisense effect of a pyrrolidine-based oxy-peptide nucleic acid (POPNA), we carried out the LacZ reporter assay using a 12-mer trans-L-POPNA conjugated with a cell-penetrating peptide (antisense reagent). The antisense effect of the conjugated POPNA (inhibition of LacZ activity) was comparable to that shown by a Nielsen-type peptide nucleic acid. Furthermore, the conjugated POPNA could switch the LacZ activity over a wide range of ambient temperatures. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2010.11.034

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

By using the NEXT-A reaction, we introduced a non-natural amino acid at the N-terminus of a peptide/protein that contained a cysteine unit. The side chain of the introduced amino acid spontaneously reacted with the cysteine to afford a cyclic peptide/protein.

DOI： 10.1039/c1cc12196k

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

We synthesized 16 pyrrolidine-based oxy-peptide nucleic acid (POPNA) monomers carrying four different nucleobases onto four different stereoisomers of pyrrolidine rings. Using these monomers, we prepared POPNA oligomers, which formed sequence-specific hybrids with DNAs. The oligomer configurations influenced the hybrid stability. The oligomers were not taken into CHO cells. However, they could enter the cell cytoplasm when mixed with the influenza virus hemagglutinin peptide-arginine heptamer conjugate. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2010.10.056

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We present three methods relating to tRNA aminoacylation with non-natural amino acids using an Escherichia coli EF-Tu E215A/D216A mutant that can bind tightly to aa-tRNAs carrying either non-natural or natural amino acids: (i) a method for improving aminoacylation efficiency, (ii) a rapid method for analysing aminoacylation efficiency without the use of radioisotope labelling and (iii) a method for purifying aminoacyl-tRNAs. Although the EF-Tu mutant may be incompatible with some kinds of non-natural amino acids, we confirmed that the EF-Tu mutant could efficiently bind to aa-tRNAs carrying various amino acids (Arg, Ser, O-methyltyrosine, Bodipy FL-aminophenylalanine and 2-acrydonylalanine). These methods may be used for the efficient in vitro synthesis of proteins containing various non-natural amino acids.

DOI： 10.1093/jb/mvq053

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC BIOSCIENCE BIOENGINEERING JAPAN  

We engineered Lactobacillus paracasei to produce a dsRNA that would trigger RNAi-induced silencing of an essential gene in the nematode Caenorhabditis elegans. The dsRNA-expressing L paracasei can be used in experiments conducted on culture plates and may also be used as an orally administrable dsRNA carrier for humans and other mammals. (C) 2009, The Society for Biotechnology, Japan. All rights reserved.

DOI： 10.1016/j.jbiosc.2009.08.002

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Authorship：Last author,　Corresponding author   Publishing type：Part of collection (book)   Publisher：Humana Press  

DOI： 10.1007/978-1-60761-588-0_17

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Bioactive small molecules such as metabolites and drugs play important roles in regulating biological functions. A technique for Visualizing such small molecules is very useful to understand their molecular mechanisms. In this study, an RNA-protein Conjugate, which consists of in RRE-RNA sensor protein (EYFP-Rev-ECFP) and an altered RRE-RNA, was constructed to detect bioactive small molecules by fluorescent resonance energy transfer (FRET). We designed a theophylline-aptamer-inserted RRE-RNA (Theo-RRE) to detect theophylline as a model target molecule. Theo-RRE formed an RNA-protein conjugate with EYFP-Rev-ECFP in the presence of theophylline. As a result, theophylline was specifically detected down to 10 mu M by the FRET increase in distinction from theophylline analogue, caffeine, in cell lysates.

DOI： 10.1021/bc9002184

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

In this study we describe the spatial regulation of RNA interference (RNAi) using an RNA-carrier protein labeled with a fluorescent dye and a light source to trigger the RNAi. We demonstrate photo-dependent gene silencing using several dyes with different excitation wavelengths. Additionally, we use light from a halogen lamp and a photomask to produce photopatterned RNAi, and laser light to trigger single-cell RNAi on cell culture plates. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jconrel.2009.04.015

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Authorship：Last author,　Corresponding author   Language：English   Publisher：ELSEVIER SCIENCE BV  

RNAi-mediated silencing of specific genes is a promising strategy for gene therapy. To utilize RNAi for therapy, an efficient and safe method for delivery of RNA into the cell cytosol is necessary. The plasma membrane is the primary, and most difficult, barrier for RNA to cross, because negatively charged RNA is strongly repulsed by the negatively charged membrane. A variety of cationic polymers can be used as RNA carriers by interacting with RNA and covering its negative charges to form a cell-penetrating complex Among the emerging candidates for RNA carriers are cationic cell-penetrating peptides (CPPs), which can cross the plasma membrane and internalize into cells together with RNA. This review focuses on CPP-based RNA delivery strategies. In using CPP-based RNA delivery, most of the RNA internalized by the cell is entrapped in endosomes. Strategies for endosomal escape of RNAs are also reviewed. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.addr.2009.04.005

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A peptide nucleic acid (PNA)-cell-penetrating peptide (CPP) conjugate (carrier PNA) was used as &apos;bridgebuilder&apos; to connect a CPP with an shRNA. The carrier PNA successfully formed a hybrid with an shRNA bearing complementary dangling bases and the shRNA was introduced into cells by the carrier PNA, and RNAi was induced by the shRNA. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2009.05.031

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

We developed novel Substrates for protease activity evaluation by fluorescence correlation spectroscopy (FCS). Substrates were labeled in a position-specific manner with a fluorophore near the N terminus and included a C-terminal, 30 kDa, highly soluble protein (elongation factor Ts [EF-Ts]). The C-terminal protein enhanced the substrate peptide Solubility and increased the molecular weight, enabling sensitive detection by FCS. Using the labeled substrates, caspase-3 and matrix metalloproteinase-9 (MMP-9) activities were confirmed by FCS. To demonstrate the Suitability of this FCS-based assay for high-throughput screening, we screened various chemical compounds for MMP-9 inhibitors. The screening results confirmed the inhibitory activity of one compound and also revealed another potential MMP-9 inhibitor. Thus, this combination of position-specific labeled protein Substrates and FCS may serve as a useful tool for evaluating activities of various proteases and for protease inhibitor screening. (C) 2009 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.ab.2009.03.049

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

The profiling of microRNAs (miRNAs) using microarray technology has been used in many recent biological and medical studies. In this study, arrays of peptide nucleic acids (PNAs) were prepared and their miRNA capture abilities were evaluated. We found that the sensitivity of 10-mer PNA probes in targeting miRNAs was much higher than that of the corresponding DNA probes and also of longer (20-mer) DNA probes.

DOI： 10.1246/cl.2009.438

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Unique taurine-containing Uridine derivatives, 5-taurinomethyluridine (tau m(5)U) and 5-taurinomethyl-2-thiouridine (tau m(5)s(2)U), which were discovered in mammalian mitochondrial tRNAs, exist at the first position of the anticodon. In this paper, we report the first efficient synthesis of tau m(5)U and tau m(5)s(2)U and describe their physicochemical properties. These modified ribonucleosides were synthesized by the reaction of 5-substituted uridine derivatives with a tetrabutylammonium salt of taurine that is highly reactive and well-soluble in common organic solvents. UV and (1)H NMR spectrometric studies revealed the structural properties of the taurine-containing base moieties and the Sugar conformations of these modified ribonucleosides.

DOI： 10.1021/jo802697r

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

In this study, an RNA isolation method was developed using a biotinylated peptide nucleic acid (PNA) that is complementary to the target RNA. Using the biotinylated PNA method, we successfully isolated several RNAs from Escherichia coli and from human total RNA in pure form. Damage to the RNA appears to be negligible by this method because the method is rapid and does not require a high temperature treatment to facilitate RNA-PNA binding.

DOI： 10.1093/jb/mvn107

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

The detection of amino acids using aminoacyl-tRNA synthetases (ARSs) as the molecular recognition element was proposed, and the binding activity and specificity of ARSs were evaluated. Using this rapid and easy method, from 15 to 50 mu M tyrosine could be measured specifically. The method suggested in this article could be realized without an amino acid labeling process or a large volume of organic solvents, and the time for measurement was reasonable. (c) 2008 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.ab.2008.03.037

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

Post-transcriptional modifications at the first ( wobble) position of the tRNA anticodon participate in precise decoding of the genetic code. To decode codons that end in a purine (R) (i.e. NNR), tRNAs frequently utilize 5-methyluridine derivatives (xm(5)U) at the wobble position. However, the functional properties of the C5-substituents of xm(5)U in codon recognition remain elusive. We previously found that mitochondrial tRNAs(Leu(UUR)) with pathogenic point mutations isolated from MELAS ( mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) patients lacked the 5-taurinomethyluridine (tau m(5)U) modification and caused a decoding defect. Here, we constructed Escherichia coli tRNAs(Leu(UUR)) with or without xm(5)U modifications at the wobble position and measured their decoding activities in an in vitro translation as well as by A-site tRNA binding. In addition, the decoding properties of tRNA(Arg) lacking mnm(5)U modification in a knock-out strain of the modifying enzyme (Delta mnmE) were examined by pulse labeling using reporter constructs with consecutive AGR codons. Our results demonstrate that the xm(5)U modification plays a critical role in decoding NNG codons by stabilizing U center dot G pairing at the wobble position. Crystal structures of an anticodon stem-loop containing tau m(5)U interacting with a UUA or UUG codon at the ribosomal A-site revealed that the m(5)U center dot G base pair does not have classical U center dot G wobble geometry. These structures provide help to explain how the tau m(5)U modification enables efficient decoding of UUG codons.

DOI： 10.1074/jbc.M800233200

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

HIV-1 TAT peptide, which is a cell-penetrating peptide (CPP), was fused to the UIA RNA-binding domain (TatU1A) to generate a sequence-specific siRNA delivery system for mammalian cells. The siRNA contained a short 5'-extension that is specifically recognized by the U1A RNA-binding domain (U1AsiRNA). Specific binding of TatU1A to the U1AsiRNA was confirmed using a gel mobility shift assay. The U1AsiRNA was internalized by cells only when it was preincubated with TatU1A before addition to the cells. Although most of the internalized siRNA seemed. to be entrapped in endocytic compartments, efficient redistribution of the entrapped siRNAs was achieved by photostimulation of a fluorophore attached to TatU1A. Once in the cytoplasm, the siRNA induced RNAi-mediated gene silencing. We refer to this delivery strategy as CLIP-RNAi. CLIP-RNAi is a promising strategy for RNAi experiments and for pinpoint RNAi therapy.

DOI： 10.1021/bc800020n

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Nonnatural amino acids have been introduced into proteins using expanded protein biosynthesis systems. However, some nonnatural amino acids, especially those containing large aromatic groups, are not efficiently incorporated into proteins. Reduced binding efficiency of aminoacylated tRNAs to elongation factor Tu (EF-Tu) is likely to limit incorporation of large amino acids. Our previous studies suggested that tRNAs carrying large nonnatural amino acids are bound less tightly to EF-Tu than natural amino acids. To expand the availability of nonnatural mutagenesis, EF-Tu from the E coli translation system was improved to accept such large amino acids. We synthesized EF-Tu mutants, in which the binding pocket of the aminoacyl moiety of aminoacyl-tRNA was enlarged. L-1-Pyrenylalanine, L-2-pyrenylalanine, and DL-2anthraquinonylalanine, which are hardly or only slightly incorporated with the wild-type EF-Tu, were successfully incorporated into a protein using these EF-Tu mutants.

DOI： 10.1021/ja075557u

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Authorship：Lead author,　Corresponding author   Language：English   Publisher：WILEY  

Most tRNAs share a common secondary structure containing a T arm, a D arm, an anticodon arm and an acceptor stem. However, there are some exceptions. Most nematode mitochondrial tRNAs and some animal mitochondrial tRNAs lack the T arm, which is necessary for binding to canonical elongation factor Tu (EF-Tu). The mitochondria of the nematode Caenorhabditis elegans have a unique EF-Tu, named EF-Tu1, whose structure has supplied clues as to how truncated tRNAs can work in translation. EF-Tu1 has a C-terminal extension of about 60 aa that is absent in canonical EF-Tu. Recent data from our laboratory strongly suggests that EF-Tu1 recognizes the D-arm instead of the T arm by a mechanism involving this C-terminal region. Further biochemical analysis of mitochondrial tRNAs and EF-Tu from the distantly related nematode Trichinella spp. and sequence information on nuclear and mitochondrial DNA in arthropods suggest that T-armless tRNAs may have arisen as a result of duplication of the EF-Tu gene. These studies provide valuable insights into the co-evolution of RNA and RNA-binding proteins.

DOI： 10.1080/15216540701218722

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC BIOSCIENCE BIOENGINEERING JAPAN  

Spodoptera frugiperda 21 (Sf21) insect cell-free protein synthesizing system was expanded to include nonnatural amino acids. Orthogonal tRNAs that work as carriers of nonnatural amino acids in the insect system were explored. Four-base codons for assigning the positions of nonnatural amino acids were also selected. Mutated streptavidin mRNAs that contained different four-base codons were prepared and added to the insect cell-free system in the presence of various tRNAs possessing the corresponding four-base anticodons. The tRNAs were chemically amino-acylated with various types of nonnatural amino acids to examine their incorporation efficiencies. Using p-nitrophenylalanine as the nonnatural amino acid and streptavidin as the target protein, tRNA sequences and the types of four-base codons were optimized to maximize the yield of the nonnatural mutant and to minimize production of full-length proteins that do not contain the nonnatural amino acid. Among the tRNA sequences taken from a variety of tRNAs of nonstandard structures, the tRNA derived from Methanosarcina acetivorans tRNA(Pyl) was the most efficient and orthogonal tRNA. Of the CGGN-type four-base codons, CGGA and CGGG were the most efficient ones for assigning the positions of nonnatural amino acids. p-Nitrophenylalanine and 2-naphthylalanine were efficiently incorporated as in the case of Escherichia coli and rabbit reticulocyte cell-free systems. Much less efficient incorporation was observed, however, for other nonnatural amino acids, indicating that the insect system is less tolerant to the structural diversity of amino acids than the E. coli cell-free system.

DOI： 10.1263/jbb.102.511

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

EF-Tu delivers aminoacyl-tRNAs to ribosomes in the translation system. However, unusual truncations found in some animal mitochondrial tRNAs seem to prevent recognition by a canonical EF-Tu. We showed previously that the chromadorean nematode has two distinct EF-Tus, one of which (EF-Tu1) binds only to T-armless aminoacyl-tRNAs and the other (EF-Tu2) binds to D-armless Ser-tRNAs. Neither of the EF-Tus can bind to canonical cloverleaf tRNAs. In this study, by analyzing the translation system of enoplean nematode Trichinella species, we address how EF-Tus and tRNAs have evolved from the canonical structures toward those of the chromadorean translation system. Trichinella mitochondria possess three types of tRNAs: cloverleaf tRNAs, which do not exist in chromadorean nematode mitochondria; T-armless tRNAs; and D-armless tRNAs. We found two mitochondrial EF-Tu species, EF-Tu1 and EF-Tu2, in Trichinella britovi. T.britovi EF-Tu2 could bind to only D-armless Ser-tRNA, as Caenorhabditis elegans EF-Tu2 does. In contrast to the case of C.elegans EF-Tu1, however, T.britovi EF-Tu1 bound to all three types of tRNA present in Trichinella mitochondria. These results suggest that Trichinella mitochondrial translation system, and particularly the tRNA-binding specificity of EF-Tu1, could be an intermediate state between the canonical system and the chromadorean nematode mitochondrial system.

DOI： 10.1093/nar/gkl526

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：PORTLAND PRESS LTD  

Nematode mitochondria possess extremely truncated tRNAs. Of 22 tRNAs, 20 lack the entire T-arm. The T-arm is necessary for the binding of canonical tRNAs and EF (elongation factor)-Tu (thermo-unstable). The nematode mitochondrial translation system employs two different EF-Tu factors named EF-Tu1 and EF-Tu2. Our previous study showed that nematode Caenorhabditis elegans EF-Tu1 binds specifically to T-armless tRNA. C. elegans EF-Tu1 has a 57-amino acid C-terminal extension that is absent from canonical EF-Tu, and the T-arm-binding residues of canonical EF-Tu are not conserved. In this study, the recognition mechanism of T-armless tRNA by EF-Tu1 was investigated. Both modification interference assays and primer extension analysis of cross-linked ternary complexes revealed that EF-Tu1 interacts not only with the tRNA acceptor stem but also with the D-arm. This is the first example of an EF-Tu recogpizing the D-arm of a tRNA. The binding activity of EF-Tu1 was impaired by deletion of only 14 residues from the C-terminus, indicating that the C-terminus of EF-Tu1 is required for its binding to T-armless tRNA. These results suggest that C. elegans EF-Tu1 recognizes the D-arm instead of the T-arm by a mechanism involving its C-terminal region. This study sheds light on the co-evolution of RNA and RNA-binding proteins in nematode mitochondria.

DOI： 10.1042/BJ20060781

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

In canonical translation systems, the single elongation factor Tu (EF-Tu) recognizes all elongator tRNAs. However, in Caenorhabditis elegans mitochondria, two distinct EF-Tu species, EF-Tu1 and EF-Tu2, recognize 20 species of T armless tRNA and two species of D armless tRNA(Ser), respectively. We previously reported that C. elegans mitochondrial EF-Tu2 specifically recognizes the serine moiety of serylated-tRNA. In this study, to identify the critical residues for the serine specificity in EF-Tu2, several residues in the amino acid binding pocket of bacterial EF-Tu were systematically replaced with corresponding EF-Tu2 residues, and the mutants were analyzed for their specificity for esterified amino acids attached to tRNAs. In this way, we obtained a bacterial EF-Tu mutant that acquired serine specificity after the introduction of 10 EF-Tu2 residues into its amino acid binding pocket. C. elegans EF-Tu2 mutants lacking serine specificity were also created by replacing seven or eight residues with bacterial residues. Further stressing the importance of these residues, we found that they are almost conserved in EF-Tu2 sequences of closely related nematodes. Thus, these three approaches reveal the critical residues essential for the unique serine specificity of C. elegans mitochondrial EF-Tu2.

DOI： 10.1021/bi060536i

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Authorship：Corresponding author   Language：English   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

DOI： 10.1016/j.ab.2005.08.008

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Nonnatural amino acids, such as fluorescent amino acids, can be introduced into proteins by using an expanded protein biosynthesis system. This approach requires orthogonal tRNAs that deliver nonnatural amino acids to a ribosome and expanded codon/anticodon pairs, like four-base codon/anticodon pairs. However, in this system, some of nonnatural amino acids are not efficiently incorporated into proteins. To expand the availability of the nonnatural mugatenesis, translation factors and tRNAs must be improved. In this study, we designed and synthesized an elongation factor Tu (EF-Tu) mutant that efficiently binds to tRNAs charged with nonnatural amino acids. We also devised new tRNAs that decode four-base codons and efficiently deliver nonnatural amino acids into ribosome.

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The ability to introduce non-natural amino acids into proteins opens up new vistas for the study of protein structure and function. This approach requires suppressor tRNAs that deliver the non-natural amino acid to a ribosome associated with an mRNA containing an expanded codon. The suppressor tRNAs must be absolutely protected from aminoacylation by any of the aminoacyl-tRNA synthetases in the protein synthesizing system, or a natural amino acid will be incorporated instead of the non-natural amino acid. Here, we found that some tRNAs with non-standard structures could work as efficient four-base suppressors fulfilling the above orthogonal conditions. Using these tRNAs, we successfully demonstrated incorporation of three different non-natural amino acids into a single protein. (c) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.febslet.2005.11.010

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Techniques for position-specific incorporation of non-natural amino acids in an in vitro protein synthesizing system are described. First, a PNA-assisted non-enzymatic tRNA aminoacylation with a variety of natural and non-natural amino acids is described. With this technique, one can aminoacylate a specific tRNA simply by adding a preformed amino acid activated ester-PNA conjugate into an in vitro protein biosynthesizing system. Second, the genetic code is expanded by introducing 4-base codons that can be exclusively translated to non-natural amino acids. The most advantageous point of the 4-base codon strategy is to introduce multiple amino acids into specific positions in single proteins by using mutually orthogonal 4-base codons and orthogonal tRNAs. An easy and quick method for preparation of tRNAs possessing 4-base anticodons is also described. Combination of the non-enzymatic aminoacylation and the 4-base codon/anticodon strategy gives an easy and widely applicable technique for incorporating a variety of non-natural amino acids into proteins in vitro. (c) 2005 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.ymeth.2005.04.009

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

In the present study, mitochondrial ribosomes of the nematode Ascaris suum were isolated and their physiochernical properties were compared to ribosomes of Escherichia coli. The sedimentation coefficient and buoyant density of A. suum mitochondrial ribosomes were determined. The sedimentation coefficient of the intact monosome was about 55 S. The buoyant density of formaldehyde-fixed ribosomes in cesium chloride was 1.40 g/cm(3), which suggests that the nematode mitoribosomes have a much higher protein composition than other mitoribosomes. The diffusion coefficients obtained from dynamic light scattering measurements were (1.48 +/- 0.04) x 10(-7) cm(2) s(-1) for 55 S mitoribosomes and (1.74 +/- 0.04) X 10(-7) cm(2) S-1 for the 70 S E. coli monosome. The diameter of mitoribosomes was measured by dynamic light-scattering analysis and electron microscopy. Though the nematode mitoribosome has a larger size than the bacterial ribosome, it does not differ significantly in size from mammalian mitoribosomes.

DOI： 10.1021/bi047833c

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

To understand the decoding property of nematode mitochondrial tRNAs with unusual secondary structures, post-transcriptional modifications at wobble positions of Ascaris suum mitochondrial tRNAs corresponding to two-codon families ending with a purine were analyzed. 5-Carboxymethylaminomethyluridine (cmnm(5)U) was identified at the wobble positions of tRNA(Lys), tRNA(Glu) and tRNA(Gln), while 5-carboxymethylaminomethyl-2-thiouridine (cmnm(5)s(2)U) was present in tRNA(UAA)(Leu) and tRNA(Trp). In most bacterial and mitochondrial tRNAs, the 2-thiouridine derivative is present in tRNAs for Lys, Gin and Gln. These is no report that cmnm(5)s(2)U is used in tRNALeu and tRNA(Trp). The unusual usage of wobble modifications might assist decoding of nematode mitochondrial mRNAs. (c) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

DOI： 10.1016/j.febslet.2005.04.009

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

The mitochondria of the nematode Ascaris suum have tRNAs with unusual secondary structures that lack either the T-arm or D-arm found in most other organisms. Of the twenty-two tRNA species present in the mitochondria of A. suum, twenty lack the entire T-arm and two serine tRNAs lack the D-arm. To understand how such unusual tRNAs work in the nematode mitochondrial translation system, we analyzed post-transcriptional modifications of 11 mitochondrial tRNA species purified from A. suum, 10 of which lacked a T-arm and one of which lacked a D-arm. The most characteristic feature of nematode mitochondrial tRNAs lacking a T-arm was the presence of 1-methyladenosine at position 9 (m(1)A(9)). Synthesis of T-armless tRNAs with or without the modified nucleoside showed that T-armless tRNAs without the modification had much lower aminoacylation and EF-Tu-binding activities than native tRNAs. The addition of a single methyl group to A9 of these tRNAs was sufficient to restore nearly native levels of amino-acylation and EF-Tu-binding activity as well as tertiary structure, suggesting that m(1)A(9w) is a key residue for the activity of T-armless tRNAs. Thus, m(1)A(9) is indispensable for the structure and function of T-armless tRNAs of nematode mitochondrial origin.

DOI： 10.1093/nar/gki309

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

Nematode mitochondria expresses two types of extremely truncated tRNAs that are specifically recognized by two distinct elongation factor Tu (EF-Tu) species named EF-Tu1 and EF-Tu2. This is unlike the canonical EF-Tu molecule that participates in the standard protein biosynthesis systems, which basically recognizes all elongator tRNAs. EF-Tu2 specifically recognizes Ser-tRNA(Ser) that lacks a D arm but has a short T arm. Our previous study led us to speculate the lack of the D arm may be essential for the tRNA recognition of EF-Tu2. However, here, we showed that the EF-Tu2 can bind to D arm-bearing Ser-tRNAs, in which the D-T arm interaction was weakened by the mutations. The ethylnitrosourea-modification interference assay showed that EF-Tu2 is unique, in that it interacts with the phosphate groups on the T stem on the side that is opposite to where canonical EF-Tu binds. The hydrolysis protection assay using several EF-Tu2 mutants then strongly suggests that seven C-terminal amino acid residues of EF-Tu2 are essential for its aminoacyl-tRNA-binding activity. Our results indicate that the formation of the nematode mitochondrial (mt) EF-Tu2/GTP/aminoacyl-tRNA ternary complex is probably supported by a unique interaction between the C-terminal extension of EF-Tu2 and the tRNA.

DOI： 10.1093/nar/gki784

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

The (6-4) photoproduct formed by ultraviolet light is known as an alkali-labile DNA lesion. Strand breaks occur at (6-4) photoproducts when UV-irradiated DNA is treated with hot alkali. We have analyzed the degradation reaction of this photoproduct under alkaline conditions using synthetic oligonucleotides. A tetramer, d(GT(6-4) TC), was prepared, and its degradation in 50 mM KOH at 60 degreesC was monitored by high performance liquid chromatography. A single peak with a UV absorption spectrum similar to that of the starting material was detected after the reaction, and this compound was regarded as an intermediate before the strand break. The formation of this intermediate was compared with intermediates from the degradation of other alkali-labile lesions such as the abasic site, thymine glycol, and 5,6-dihydrothymine. The results strongly suggested that the first step of the alkali degradation of the (6- 4) photoproduct was the hydrolysis between the N3 and C4 positions of the 5'-pyrimidine component. Analyses by NMR spectroscopy and mass spectrometry supported the chemical structure of this product. Assays of the complex formation with XPC . HR23B and the translesion synthesis by DNA polymerase eta revealed that the biochemical properties are indistinguishable between the intact and hydrolyzed photoproducts.

DOI： 10.1074/jbc.M307186200

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

The introduction of modified or labeled nucleotides into RNA is a powerful RNA engineering tool as it enables us to investigate how native RNA modifications affect RNA function and structure. It also helps in the structural analysis of RNA. A modified nucleotide can be introduced into a specific position of RNA by the method of two-step enzymatic ligation of RNA fragments. However, this method requires a complicated purification step between the two ligation steps that results in low yields of the ligation product. Here we have developed a new ligation technique employing periodate oxide that eliminates this purification step. This increases the total yield of the ligation product and makes it a faster procedure.

DOI： 10.1093/nar/gng145

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Authorship：Lead author   Language：English   Publisher：NATURE PUBLISHING GROUP  

DOI： 10.1038/nsb826

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Language：English  

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

Caenorhabditis elegans mitochondria have two elongation factor (EF)-Tu species, denoted EF-Tu1 and EF-Tu2. Recombinant nematode EF-Ts purified from Escherichia coli bound both of these molecules and also stimulated the translational activity of EF-Tu, indicating that the nematode EF-Ts homolog is a functional EF-Ts protein of mitochondria. Complexes formed by the interaction of nematode EF-Ts with EF-Tu1 and EF-Tu2 could be detected by native gel electrophoresis and purified by gel filtration. Although the nematode mitochondrial (mt) EF-Tu molecules are extremely unstable and easily form aggregates, native gel electrophoresis and gel filtration analysis revealed that EF-Tu.EF-Ts complexes are significantly more soluble. This indicates that nematode EF-Ts can be used to stabilize homologous EF-Tu molecules for experimental purposes. The EF-Ts bound to two eubacterial EF-Tu species (E.coli and Thermus thermophilus). Although the EF-Ts did not bind to bovine mt EF-Tu, it could bind to a chimeric nematode-bovine EF-Tu molecule containing domains 1 and 2 from bovine mt EF-Tu. Thus, the nematode EF-Ts appears to have a broad specificity for EF-Tu molecules from different species.

DOI： 10.1093/nar/gkf679

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CAMBRIDGE UNIV PRESS  

In the second step of the two consecutive transesterifications of the self-splicing reaction of the group I intron, the conserved guanosine at the 31 terminus of the intron (omegaG) binds to the guanosine-binding site (GBS) in the intron. In the present study, we designed a 22-nt model RNA (GBS/omegaG) including the GBS and omegaG from the Tetrahymena group I intron, and determined the solution structure by NMR methods. In this structure, omegaG is recognized by the formation of a base triple with the G2649.C311 base pair, and this recognition is stabilized by the stacking interaction between omegaG and C262. The bulged structure at A263 causes a large helical twist angle (40 +/- 8degrees) between the G264.C311 and C262.G312 base pairs. We named this type of binding pocket with a bulge and a large twist, formed on the major groove, a "Bulge-and-Twist" (BT) pocket. With another twist angle between the C262.G312 and G413.C313 base pairs (45 +/- 10degrees), the axis of GBS/omegaG is kinked at the GBS region. This kinked axis superimposes well on that of the corresponding region in the structure model built on a 5.0 Angstrom resolution electron density map (Golden et al., Science, 1998, 282:345-358). This compact structure of the GBS is also consistent with previous biochemical studies on group I introns. The BT pockets are also found in the arginine-binding site of the HIV-TAR RNA, and within the 16S rRNA and the 23S rRNA.

DOI： 10.1017/S1355838202026043

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

The tertiary structure of Ascaris suum mitochondrial tRNA(VCU)(Ser) was examined by nuclear magnetic resonance analysis using its transcript, since tRNA(UCU)(Ser), lacking the D arm and possessing a truncated T arm, is the shortest of all the known tRNAs. Most basepairs in the proposed secondary structure of tRNA(UCU)(Ser) were shown to exist, but the connector region comprising the truncated D loop and the extra loop was flexible. This flexibility, would enable adjustment of the mutual distance between the 3'-terminus and the anticodon consistent with that of usual tRNAs. Thus, tRNA(UCU)(Ser) appears to function in a similar way to that of usual tRNAs in the ribosome. (C) 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE AMERICA INC  

An unnatural base pair of 2-amino-6-(2-thienyl) purine (denoted by s) and pyridin-2-one (denoted by y) was developed to expand the genetic code. The ribonucleoside triphosphate of y was site-specifically incorporated into RNA, opposite s in a template, by T7 RNA polymerase. This transcription was coupled with translation in an Escherichia coli cell-free system. The yAG codon in the transcribed ras mRNA was recognized by the CUs anticodon of a yeast tyrosine transfer RNA (tRNA) variant, which had been enzymatically aminoacylated with an unnatural amino acid, 3-chlorotyrosine. Site-specific incorporation of 3-chlorotyrosine into the Ras protein was demonstrated by liquid chromatography-mass spectrometry (LC-MS) analysis of the products. This coupled transcription-translation system will permit the efficient synthesis of proteins with a tyrosine analog at the desired position.

DOI： 10.1038/nbt0202-177

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC  

We have found the gene for a translation elongation factor Tu (EF-Tu) homologue in the genome of the nematode Caenorhabditis elegans, Because the corresponding protein was detected immunologically in a nematode mitochondrial (mt) extract, it could be regarded as a nematode mt EF-Tu. The protein possesses an extension of about 57 amino acids (we call this domain 3') at the C terminus, which is not found in any other known EF-Tu, Because most nematode mt tRNAs lack a T stem, domain 3' may be related to this feature. The nematode EF-Tu bound to nematode T stem-lacking tRNA, but bacterial EF-Tu was unable to do so. A series of domain exchange experiments strongly suggested that domains 3 and 3' are essential for binding to T stem-lacking tRNAs, This finding may constitute a novel example of the co-evolution of a structurally simplified RNA and the cognate RNA-binding protein, the latter having apparently acquired an additional domain to compensate for the lack of a binding site(s) on the RNA.

DOI： 10.1074/jbc.M011118200

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATL ACAD SCIENCES  

An unnatural base pair of 2-amino-6-(N,N-dimethylamino)purine (designated as x) and pyridin-2-one (designated as y) has been developed for specific transcription. The ribonucleoside triphosphates of y and a modified y, 5-methylpyridin-2-one, are selectively incorporated into RNA opposite x in the templates by T7 RNA polymerase, In addition, the sequences of the DNA templates containing x can be confirmed by a dideoxynucleotide chain-terminator method supplemented with the deoxynucleoside triphosphate of y, The bulky dimethylamino group of x in the templates effectively eliminates noncognate pairing with the natural bases. These results enable RNA biosynthesis for the specific incorporation of unnatural nucleotides at the desired positions.

DOI： 10.1073/pnas.091532698

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPANESE BIOCHEMICAL SOC  

Most nematode mitochondrial (mt) tRNAs have a TV-replacement loop (TV loop) which replaces the normal T arm and the variable loop in standard tRNAs with a less-structured loop. The tertiary structure of such tRNAs has been discussed theoretically with reference to the crystal structure of yeast tRNA(Phe) [Wolstenholme et al, (1994) Nucleic Acids Res. 22, 4300-4306] and examined experimentally by chemical and enzymatic probing [Watanabe et al. (1994) J, Biol. Chem. 269, 22902-22906]. The results suggest that most regions of the tRNA other than the TV loop are folded in a similar manner to yeast tRNA(Phe). To confirm this notion more clearly, the tertiary structure of Ascaris suum mt tRNA(Met) was analyzed by NMR using various synthetic tRNAs site-specifically labeled with stable isotopes, which were prepared by a combination of chemical synthesis and enzymatic ligation, Tertiary interactions involving G(L2), G(L3), U(L4), and U8 were observed in the NMR spectra of the labeled tRNAs, but those relating to G(L5) were not. On the basis of these results, a possible tertiary structural model of nematode mitochondrial tRNA(Met) was constructed.

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN BIOCHEMICAL SOC  

RNA samples corresponding to Ascaris suum mitochondrial tRNA(Met) were chemically and automatically synthesized in amounts sufficient for NMR measurement. Conventional and rapid deprotection methods gave tRNA samples with the same amino acid-accepting activity as those prepared by other method; enzymatic synthesis, and enzymatic ligation of chemically synthesized fragments. The synthetic tRNA showed the same H-1-NMR spectrum in the iminoproton region as the ligated tRNA, This rapid and reliable preparation method thus provides biologically active tRNA for NMR measurement, and further, it is applicable for synthesis of other large synthetic RNAs, by combining the site-specific isotopic labeling method.

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS UNITED KINGDOM  

Ascaris suum mitochondrial tRNA(Met) lacking the entire T stem was prepared by enzymatic ligation of two chemically synthesized RNA fragments. The synthetic tRNA could be charged with methionine by A.suum mitochondrial extract, although the charging activity was considerably low compared with that of the native tRNA, probably due to lack of modification, Enzymatic probing of the synthetic tRNA showed a very similar digestion pattern to that of the native tRNA(Met), which has already been concluded to take an L-shape-like structure [Watanabe et al, (1994) J. Biol. Chem., 269, 22902-22906], These results suggest that the synthetic tRNA possesses almost the same conformation as the native one, irrespective of the presence or absence of modified residues. The method of preparing the bizarre tRNA used here will provide a useful tool for elucidating the tertiary structure of such tRNAs, because they can be obtained without too much difficulty in the amounts necessary for physicochemical studies such as NMR spectroscopy.

Web of Science

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MARCEL DEKKER INC  

Sulfated polysaccharide which had a relatively high degree of sulfation showed cytotoxicity to 3T3-L1 fibroblasts. Acidic and basic fibroblast growth factors inhibited the cell damage caused by the sulfated polysaccharides, while epidermal growth factor and platelet growth factor had no effects.

Web of Science

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Effects of synthetic polyanions on the mitogenic activity of fibroblast growth factors were investigated. Poly(vinylsulfonate) contributed to potentiate the activity of the acidic fibroblast growth factor, while the carboxyl group was quite effective for basic fibroblast growth factor.

DOI： 10.1246/cl.1994.1407

Web of Science

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Total pages：viii, 265p   Language：Japanese

CiNii Books

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DOI： 10.1007/978-94-017-8896-0_19

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Authorship：Last author  

J-GLOBAL

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Authorship：Lead author,　Corresponding author  

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Authorship：Lead author,　Corresponding author  

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Authorship：Lead author,　Corresponding author  

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Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-23651221/

Authorship：Lead author,　Corresponding author   Language：Japanese  

CiNii Article

CiNii Books

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Authorship：Lead author,　Corresponding author  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publisher：日本生化学会  

CiNii Article

CiNii Books

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Other Link： https://search.jamas.or.jp/link/ui/2009151587

Authorship：Lead author,　Corresponding author  

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Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-19021034/

Authorship：Lead author,　Corresponding author  

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Authorship：Lead author   Language：Japanese   Publisher：(株)日本臨床社  

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Recently, methods for delivery of peptide and RNA to target cells are widely studied for cell research and drug delivery strategies. However, the delivery methods sometimes have problems such as cytotoxicity and ineffective delivery. In some methods, target molecules tend to be trapped in endosome and degraded by lysosome when introduced to cells. In this study, ultrasound-dependent peptide / nanoparticle delivery method was developed. We developed a molecular conjugate of a cell-penetrating peptide, a sonosensitizer and a functional peptide / nanoparticle. This molecule was trapped in endosome when cells were incubated with the molecule. However, we succeeded in cytoplasmic delivery of the molecule that escape from endosome by ultrasound irradiation.

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Application no：特願2008-1174884  Date applied：2008.4.28

Announcement no：特開2008-301812 

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Application no：特願2007-37041  Date applied：2007.2.16

Announcement no：特開2008-301812 

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