研究者詳細 - 久保田　翔

論文 - 久保田　翔

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Chromatin modifier Hmga2 promotes adult hematopoietic stem cell function and blood regeneration in stress conditions 査読

Sho Kubota, Yuqi Sun, Mariko Morii, Jie Bai, Takako Ideue, Mayumi Hirayama, Supannika Sorin, Eerdunduleng, Takako Yokomizo-Nakano, Motomi Osato, Ai Hamashima, Mihoko Iimori, Kimi Araki, Terumasa Umemoto, Goro Sashida

The EMBO Journal 43 ( 13 ) 2661 - 2684 2024年5月

担当区分：筆頭著者掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

Abstract

The molecular mechanisms governing the response of hematopoietic stem cells (HSCs) to stress insults remain poorly defined. Here, we investigated effects of conditional knock-out or overexpression of Hmga2 (High mobility group AT-hook 2), a transcriptional activator of stem cell genes in fetal HSCs. While Hmga2 overexpression did not affect adult hematopoiesis under homeostasis, it accelerated HSC expansion in response to injection with 5-fluorouracil (5-FU) or in vitro treatment with TNF-α. In contrast, HSC and megakaryocyte progenitor cell numbers were decreased in Hmga2 KO animals. Transcription of inflammatory genes was repressed in Hmga2-overexpressing mice injected with 5-FU, and Hmga2 bound to distinct regions and chromatin accessibility was decreased in HSCs upon stress. Mechanistically, we found that casein kinase 2 (CK2) phosphorylates the Hmga2 acidic domain, promoting its access and binding to chromatin, transcription of anti-inflammatory target genes, and the expansion of HSCs under stress conditions. Notably, the identified stress-regulated Hmga2 gene signature is activated in hematopoietic stem progenitor cells of human myelodysplastic syndrome patients. In sum, these results reveal a TNF-α/CK2/phospho-Hmga2 axis controlling adult stress hematopoiesis.

DOI： 10.1038/s44318-024-00122-4

その他リンク： https://www.embopress.org/doi/full/10.1038/s44318-024-00122-4

TIF1β activates leukemic transcriptional program in HSCs and promotes BCR::ABL1-induced myeloid leukemia 査読

Mariko Morii, Sho Kubota, Mihoko Iimori, Takako Yokomizo-Nakano, Ai Hamashima, Jie Bai, Akiho Nishimura, Masayoshi Tasaki, Yukio Ando, Kimi Araki, Goro Sashida

Leukemia 38 ( 6 ) 1275 - 1286 2024年5月

Exposure to microbial products followed by loss of Tet2 promotes myelodysplastic syndrome via remodeling HSCs. 査読国際誌

Takako Yokomizo-Nakano, Ai Hamashima, Sho Kubota, Jie Bai, Supannika Sorin, Yuqi Sun, Kenta Kikuchi, Mihoko Iimori, Mariko Morii, Akinori Kanai, Atsushi Iwama, Gang Huang, Daisuke Kurotaki, Hitoshi Takizawa, Hirotaka Matsui, Goro Sashida

The Journal of experimental medicine 220 ( 7 ) 2023年7月

記述言語：英語掲載種別：研究論文（学術雑誌）

Aberrant innate immune signaling in myelodysplastic syndrome (MDS) hematopoietic stem/progenitor cells (HSPCs) has been implicated as a driver of the development of MDS. We herein demonstrated that a prior stimulation with bacterial and viral products followed by loss of the Tet2 gene facilitated the development of MDS via up-regulating the target genes of the Elf1 transcription factor and remodeling the epigenome in hematopoietic stem cells (HSCs) in a manner that was dependent on Polo-like kinases (Plk) downstream of Tlr3/4-Trif signaling but did not increase genomic mutations. The pharmacological inhibition of Plk function or the knockdown of Elf1 expression was sufficient to prevent the epigenetic remodeling in HSCs and diminish the enhanced clonogenicity and the impaired erythropoiesis. Moreover, this Elf1-target signature was significantly enriched in MDS HSPCs in humans. Therefore, prior infection stress and the acquisition of a driver mutation remodeled the transcriptional and epigenetic landscapes and cellular functions in HSCs via the Trif-Plk-Elf1 axis, which promoted the development of MDS.

DOI： 10.1084/jem.20220962

Overexpression of RUNX3 represses RUNX1 to drive transformation of myelodysplastic syndrome. 査読国際誌

Takako Yokomizo-Nakano, Sho Kubota, Jie Bai, Ai Hamashima, Mariko Morii, Yuqi Sun, Seiichiro Katagiri, Mihoko Iimori, Akinori Kanai, Daiki Tanaka, Motohiko Oshima, Yuka Harada, Kazuma Ohyashiki, Atsushi Iwama, Hironori Harada, Motomi Osato, Goro Sashida

Cancer research 80 ( 12 ) 2523 - 2536 2020年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

RUNX3, a RUNX family transcription factor, regulates normal hematopoiesis and functions as a tumor suppressor in various tumors in humans and mice. However, emerging studies have documented increased expression of RUNX3 in hematopoietic stem/progenitor cells (HSPC) of a subset of patients with myelodysplastic syndrome (MDS) showing a worse outcome, suggesting an oncogenic function for RUNX3 in the pathogenesis of hematological malignancies. To elucidate the oncogenic function of RUNX3 in the pathogenesis of MDS in vivo, we generated a RUNX3-expressing, Tet2-deficient mouse model with the pan-cytopenia and dysplastic blood cells characteristic of MDS in patients. RUNX3-expressing cells markedly suppressed the expression levels of Runx1, a critical regulator of hemaotpoiesis in normal and malignant cells, as well as its target genes, which included crucial tumor suppressors such as Cebpa and Csf1r. RUNX3 bound these genes and remodeled their Runx1 binding regions in Tet2-deficient cells. Overexpression of RUNX3 inhibited the transcriptional function of Runx1 and compromised hematopoiesis to facilitate the development of MDS in the absence of Tet2, indicating that RUNX3 is an oncogene. Furthermore, overexpression of RUNX3 activated the transcription of Myc target genes and rendered cells sensitive to inhibition of Myc-Max heterodimerization. Collectively, these results reveal the mechanism by which RUNX3 overexpression exerts oncogenic effects on the cellular function of and transcriptional program in Tet2-deficient stem cells to drive the transformation of MDS.

DOI： 10.1158/0008-5472.CAN-19-3167

[Enhancer hijacking via disease-specific chromosomal translocation in blastic plasmacytoid dendritic cell neoplasm]. 招待査読

Sho Kubota

臨床血液 2020年

Lineage-specific RUNX2 super-enhancer activates MYC and promotes the development of blastic plasmacytoid dendritic cell neoplasm. 査読国際誌

Sho Kubota, Kenji Tokunaga, Tomohiro Umezu, Takako Yokomizo-Nakano, Yuqi Sun, Motohiko Oshima, Kar Tong Tan, Henry Yang, Akinori Kanai, Eisaku Iwanaga, Norio Asou, Takahiro Maeda, Naomi Nakagata, Atsushi Iwama, Kazuma Ohyashiki, Motomi Osato, Goro Sashida

Nature communications 10 ( 1 ) 3943 - 3943 2019年8月

Role for Tyrosine Phosphorylation of A-kinase Anchoring Protein 8 (AKAP8) in its Dissociation from Chromatin and the Nuclear Matrix. 査読

Sho Kubota, Mariko Morii, Ryuzaburo Yuki, Noritaka Yamaguchi, Hiromi Yamaguchi, Kazumasa Aoyama, Takahisa Kuga, Takeshi Tomonaga, Naoto Yamaguchi

The Journal of biological chemistry 290 ( 17 ) 10891 - 10904 2015年4月

Phosphorylation of KRAB-associated Protein 1 (KAP1) at Tyr-449, Tyr-458, and Tyr-517 by Nuclear Tyrosine Kinases Inhibits the Association of KAP1 and Heterochromatin Protein 1α (HP1α) with Heterochromatin 査読

Sho Kubota, Yasunori Fukumoto, Kazumasa Aoyama, Kenichi Ishibashi, Ryuzaburo Yuki, Takao Morinaga, Takuya Honda, Noritaka Yamaguchi, Takahisa Kuga, Takeshi Tomonaga, Naoto Yamaguchi

Journal of Biological Chemistry 288 ( 24 ) 17871 - 17883 2013年6月

Discovery of a Compound That Inhibits IRE1α S-Nitrosylation and Preserves the Endoplasmic Reticulum Stress Response under Nitrosative Stress 査読

Haruna Kurogi, Nobumasa Takasugi, Sho Kubota, Ashutosh Kumar, Takehiro Suzuki, Naoshi Dohmae, Daisuke Sawada, Kam Y.J. Zhang, Takashi Uehara

ACS Chemical Biology 19 ( 12 ) 2429 - 2437 2024年11月

Epigenetic Regulation of CXC Chemokine Expression by Environmental Electrophiles Through DNA Methyltransferase Inhibition 査読

Tomoki Tsuchida, Sho Kubota, Shizuki Kamiuezono, Nobumasa Takasugi, Akihiro Ito, Yoshito Kumagai, Takashi Uehara

International Journal of Molecular Sciences 25 ( 21 ) 11592 - 11592 2024年10月

掲載種別：研究論文（学術雑誌）出版者・発行元：MDPI AG

Ubiquitously distributed environmental electrophiles covalently modify DNA and proteins, potentially leading to adverse health effects. However, the impacts of specific electrophiles on target proteins and their physiological roles remain largely unknown. In the present study, we focused on DNA methylation, which regulates gene expression and physiological responses. A total of 45 environmental electrophiles were screened for inhibitory effects on the activity of DNA methyltransferase 3B (DNMT3B), a key enzyme in DNA methylation, and four compounds were identified. We focused on 1,2-naphthoquinone (1,2-NQ), an air pollutant whose toxicity has been reported previously. Interestingly, we found that 1,2-NQ modified multiple lysine and histidine residues in DNMT3B, one of which was near the active site in DNMT3B. It was found that 1,2-NQ altered gene expression and evoked inflammatory responses in lung adenocarcinoma cell lines. Furthermore, we found that 1,2-NQ upregulated CXCL8 expression through DNA demethylation of the distal enhancer and promoted cancer cell growth. Our study reveals novel mechanisms of epigenetic regulation by environmental electrophiles through the inhibition of DNMT3B activity and suggests their physiological impact.

DOI： 10.3390/ijms252111592

Therapeutic potential of 4-phenylbutyric acid against methylmercury-induced neuronal cell death in mice 査読

Ryohei Miki, Ryosuke Nomura, Yuta Iijima, Sho Kubota, Nobumasa Takasugi, Takao Iwawaki, Masatake Fujimura, Takashi Uehara

Archives of Toxicology 2024年10月

掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

Abstract

Methylmercury (MeHg) is an environmental neurotoxin that induces damage to the central nervous system and is the causative agent in Minamata disease. The mechanisms underlying MeHg neurotoxicity remain largely unknown, and there is a need for effective therapeutic agents, such as those that target MeHg-induced endoplasmic reticulum (ER) stress and the unfolded protein response (UPR), which is activated as a defense mechanism. We investigated whether intraperitoneal administration of the chemical chaperone, 4-phenylbutyric acid (4-PBA), at 120 mg/kg/day can alleviate neurotoxicity in the brains of mice administered 50 ppm MeHg in drinking water for 5 weeks. 4-PBA significantly reduced MeHg-induced ER stress, neuronal apoptosis, and neurological symptoms. Furthermore, 4-PBA was effective even when administered 2 weeks after the initiation of exposure to 30 ppm MeHg in drinking water. Our results strongly indicate that ER stress and the UPR are key processes involved in MeHg toxicity, and that 4-PBA is a novel therapeutic candidate for MeHg-induced neurotoxicity.

DOI： 10.1007/s00204-024-03902-3

その他リンク： https://link.springer.com/article/10.1007/s00204-024-03902-3/fulltext.html

Epigenetic Regulation of Carbonic Anhydrase 9 Expression by Nitric Oxide in Human Small Airway Epithelial Cells 査読

Yuto Moriya, Sho Kubota, Yuta Iijima, Nobumasa Takasugi, Takashi Uehara

Biological and Pharmaceutical Bulletin 47 ( 6 ) 1119 - 1122 2024年6月

Methyl vinyl ketone and its analogs covalently modify PI3K and alter physiological functions by inhibiting PI3K signaling 査読

Atsushi Morimoto, Nobumasa Takasugi, Yuexuan Pan, Sho Kubota, Naoshi Dohmae, Yumi Abiko, Koji Uchida, Yoshito Kumagai, Takashi Uehara

Journal of Biological Chemistry 300 ( 3 ) 105679 - 105679 2024年3月

Multiple myeloma–associated DIS3 gene is essential for hematopoiesis, but loss of DIS3 is insufficient for myelomagenesis 査読

Hiroto Ohguchi, Yasuyo Ohguchi, Sho Kubota, Kan Etoh, Ai Hamashima, Shingo Usuki, Takako Yokomizo-Nakano, Jie Bai, Takeshi Masuda, Yawara Kawano, Takeshi Harada, Mitsuyoshi Nakao, Takashi Minami, Teru Hideshima, Kimi Araki, Goro Sashida

Blood Neoplasia 1 ( 1 ) 100005 - 100005 2024年3月

Attenuation of protein arginine dimethylation via S-nitrosylation of protein arginine methyltransferase 1 査読

Rikako Taniguchi, Yuto Moriya, Naoshi Dohmae, Takehiro Suzuki, Kengo Nakahara, Sho Kubota, Nobumasa Takasugi, Takashi Uehara

Journal of Pharmacological Sciences 154 ( 3 ) 209 - 217 2024年3月

Transcriptome analysis in various cell lines exposed to nitric oxide. 査読

Tohta Mizushima, Sho Kubota, Yuta Iijima, Nobumasa Takasugi, Takashi Uehara

The Journal of toxicological sciences 49 ( 6 ) 281 - 288 2024年

記述言語：英語掲載種別：研究論文（学術雑誌）

Nitric oxide (NO) plays a physiological role in signal transduction and excess or chronic NO has toxic effects as an inflammatory mediator. NO reversibly forms protein S-nitrosylation and exerts toxicological functions related to disease progression. DNA methyltransferases, epigenome-related enzymes, are inhibited in enzymatic activity by S-nitrosylation. Therefore, excess or chronic NO exposure may cause disease by altering gene expression. However, the effects of chronic NO exposure on transcriptome are poorly understood. Here, we performed transcriptome analysis of A549, AGS, HEK293T, and SW48 cells exposed to NO (100 μM) for 48 hr. We showed that the differentially expressed genes were cell-specific. Gene ontology analysis showed that the functional signature of differentially expressed genes related to cell adhesion or migration was upregulated in several cell lines. Gene set enrichment analysis indicated that NO stimulated inflammation-related gene expression in various cell lines. This finding supports previous studies showing that NO is closely involved in inflammatory diseases. Overall, this study elucidates the pathogenesis of NO-associated inflammatory diseases by focusing on changes in gene expression.

DOI： 10.2131/jts.49.281

CARD11 mutation and HBZ expression induce lymphoproliferative disease and adult T-cell leukemia/lymphoma 査読

Takuro Kameda, Kotaro Shide, Ayako Kamiunten, Yasunori Kogure, Daisuke Morishita, Junji Koya, Yuki Tahira, Keiichi Akizuki, Takako Yokomizo-Nakano, Sho Kubota, Kosuke Marutsuka, Masaaki Sekine, Tomonori Hidaka, Yoko Kubuki, Yuichi Kitai, Tadashi Matsuda, Akinori Yoda, Takayuki Ohshima, Midori Sugiyama, Goro Sashida, Keisuke Kataoka, Seishi Ogawa, Kazuya Shimoda

Communications Biology 5 ( 1 ) 2022年11月

掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

Abstract

Adult T-cell leukemia/lymphoma (ATL) is caused by human T-cell leukemia virus type 1 (HTLV-1). In addition to HTLV-1 bZIP factor (HBZ), a leukemogenic antisense transcript of HTLV-1, abnormalities of genes involved in TCR-NF-κB signaling, such as CARD11, are detected in about 90% of patients. Utilizing mice expressing CD4⁺ T cell-specific CARD11(E626K) and/or CD4⁺ T cell-specific HBZ, namely CARD11(E626K)^CD4-Cre mice, HBZ transgenic (Tg) mice, and CARD11(E626K)^CD4-Cre;HBZ Tg double transgenic mice, we clarify these genes’ pathogenetic effects. CARD11(E626K)^CD4-Cre and HBZ Tg mice exhibit lymphocytic invasion to many organs, including the lungs, and double transgenic mice develop lymphoproliferative disease and increase CD4⁺ T cells in vivo. CARD11(E626K) and HBZ cooperatively activate the non-canonical NF-κB pathway, IRF4 targets, BATF3/IRF4/HBZ transcriptional network, MYC targets, and E2F targets. Most KEGG and HALLMARK gene sets enriched in acute-type ATL are also enriched in double transgenic mice, indicating that these genes cooperatively contribute to ATL development.

DOI： 10.1038/s42003-022-04284-x

その他リンク： https://www.nature.com/articles/s42003-022-04284-x

HMGN3 represses transcription of epithelial regulators to promote migration of cholangiocarcinoma in a SNAI2-dependent manner. 査読国際誌

Supannika Sorin, Sho Kubota, Sofiane Hamidi, Takako Yokomizo-Nakano, Kulthida Vaeteewoottacharn, Sopit Wongkham, Sakda Waraasawapati, Chawalit Pairojkul, Jie Bai, Mariko Morii, Guojun Sheng, Kanlayanee Sawanyawisuth, Goro Sashida

FASEB journal : official publication of the Federation of American Societies for Experimental Biology 36 ( 7 ) e22345 2022年7月

記述言語：英語掲載種別：研究論文（学術雑誌）

High mobility group nucleosome-binding protein 3 (HMGN3), a member of the HMGN family, modulates the structure of chromatin and regulates transcription through transcription factors. HMGN3 has been implicated in the development of various cancers; however, the underlying mechanisms remain unclear. We herein demonstrated that the high expression of HMGN3 correlated with the metastasis of liver fluke infection-induced cholangiocarcinoma (CCA) in patients in northeastern Thailand. The knockdown of HMGN3 in CCA cells significantly impaired the oncogenic properties of colony formation, migration, and invasion. HMGN3 inhibited the expression of and blocked the intracellular polarities of epithelial regulator genes, such as the CDH1/E-cadherin and TJAP1 genes in CCA cells. A chromatin immunoprecipitation sequencing analysis revealed that HMGN3 required the transcription factor SNAI2 to bind to and repress the expression of epithelial regulator genes, at least in part, due to histone deacetylases (HDACs), the pharmacological inhibition of which reactivated these epithelial regulators in CCA, leading to impairing the cell migration capacity. Therefore, the overexpression of HMGN3 represses the transcription of and blocks the polarities of epithelial regulators in CCA cells in a manner that is dependent on the SNAI2 gene and HDACs.

DOI： 10.1096/fj.202200386R

ATP citrate lyase controls hematopoietic stem cell fate and supports bone marrow regeneration. 査読国際誌

Terumasa Umemoto, Alban Johansson, Shah Adil Ishtiyaq Ahmad, Michihiro Hashimoto, Sho Kubota, Kenta Kikuchi, Haruki Odaka, Takumi Era, Daisuke Kurotaki, Goro Sashida, Toshio Suda

The EMBO journal 41 ( 8 ) e109463 2022年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

In order to support bone marrow regeneration after myeloablation, hematopoietic stem cells (HSCs) actively divide to provide both stem and progenitor cells. However, the mechanisms regulating HSC function and cell fate choice during hematopoietic recovery remain unclear. We herein provide novel insights into HSC regulation during regeneration by focusing on mitochondrial metabolism and ATP citrate lyase (ACLY). After 5-fluorouracil-induced myeloablation, HSCs highly expressing endothelial protein C receptor (EPCRhigh ) were enriched within the stem cell fraction at the expense of more proliferative EPCRLow HSCs. These EPCRHigh HSCs were initially more primitive than EPCRLow HSCs and enabled stem cell expansion by enhancing histone acetylation, due to increased activity of ACLY in the early phase of hematopoietic regeneration. In the late phase of recovery, HSCs enhanced differentiation potential by increasing the accessibility of cis-regulatory elements in progenitor cell-related genes, such as CD48. In conditions of reduced mitochondrial metabolism and ACLY activity, these HSCs maintained stem cell phenotypes, while ACLY-dependent histone acetylation promoted differentiation into CD48+ progenitor cells. Collectively, these results indicate that the dynamic control of ACLY-dependent metabolism and epigenetic alterations is essential for HSC regulation during hematopoietic regeneration.

DOI： 10.15252/embj.2021109463

The acidic domain of Hmga2 and the domain's linker region are critical for driving self-renewal of hematopoietic stem cell. 査読国際共著国際誌

Yuqi Sun, Sho Kubota, Mihoko Iimori, Ai Hamashima, Haruka Murakami, Jie Bai, Mariko Morii, Takako Yokomizo-Nakano, Motomi Osato, Kimi Araki, Goro Sashida

International journal of hematology 115 ( 4 ) 553 - 562 2022年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

High mobility group AT-hook 2 (Hmga2) is a chromatin modifier protein that plays a critical role in fetal development and leukemia propagation by binding to chromatin and DNA via its AT-hook domains. However, the molecular mechanisms by which Hmga2 activates the expression of target genes to drive the self-renewal of hematopoietic stem cells (HSCs) remain unclear. We generated Rosa26 locus Hmga2 conditional knock-in mice and found that overexpression of Hmga2 promoted self-renewal of normal HSCs, but maintained their fitness in bone marrow, and consequently was not sufficient to initiate malignancy. This result is consistent with previous findings showing that Hmga2 is a proto-oncogene. We also assessed the cellular functions of Hmga2 mutants lacking functional domains and demonstrated that the C-terminus acidic domain of Hmga2 and the domain's linker region were critical for activating genes involved in stem cell signatures, such as the Igf2bp2 gene, to drive proliferation of HSCs. In contrast, overexpression of Hmga1, a member of the Hmga family with a different linker region, did not drive proliferation of HSCs. Our results reveal a critical role for the acidic domain of Hmga2 and the domain's linker region in modulating the transcription and self-renewal functions of HSCs.

DOI： 10.1007/s12185-021-03274-9

RUNX1-ETO (RUNX1-RUNX1T1) induces myeloid leukemia in mice in an age-dependent manner. 査読国際誌

Mohamed Gaber Abdallah, Akiko Niibori-Nambu, Mariko Morii, Takako Yokomizo, Tomomasa Yokomizo, Takako Ideue, Sho Kubota, Vania Swee Imm Teoh, Michelle Meng Huang Mok, Chelsia Qiuxia Wang, Abdellah Ali Omar, Kenji Tokunaga, Eisaku Iwanaga, Masao Matsuoka, Norio Asou, Naomi Nakagata, Kimi Araki, Mabrouk AboElenin, Sayed Hamada Madboly, Goro Sashida, Motomi Osato

Leukemia 35 ( 10 ) 2983 - 2988 2021年10月

Inflammation-driven senescence-associated secretory phenotype in cancer-associated fibroblasts enhances peritoneal dissemination. 査読国際誌

Tadahito Yasuda, Mayu Koiwa, Atsuko Yonemura, Keisuke Miyake, Ryusho Kariya, Sho Kubota, Takako Yokomizo-Nakano, Noriko Yasuda-Yoshihara, Tomoyuki Uchihara, Rumi Itoyama, Luke Bu, Lingfeng Fu, Kota Arima, Daisuke Izumi, Shiro Iwagami, Kojiro Eto, Masaaki Iwatsuki, Yoshifumi Baba, Naoya Yoshida, Hiroto Ohguchi, Seiji Okada, Keisuke Matsusaki, Goro Sashida, Akiko Takahashi, Patrick Tan, Hideo Baba, Takatsugu Ishimoto

Cell reports 34 ( 8 ) 108779 - 108779 2021年2月

記述言語：英語掲載種別：研究論文（学術雑誌）

In the tumor microenvironment, senescent non-malignant cells, including cancer-associated fibroblasts (CAFs), exhibit a secretory profile under stress conditions; this senescence-associated secretory phenotype (SASP) leads to cancer progression and chemoresistance. However, the role of senescent CAFs in metastatic lesions and the molecular mechanism of inflammation-related SASP induction are not well understood. We show that pro-inflammatory cytokine-driven EZH2 downregulation maintains the SASP by demethylating H3K27me3 marks in CAFs and enhances peritoneal tumor formation of gastric cancer (GC) through JAK/STAT3 signaling in a mouse model. A JAK/STAT3 inhibitor blocks the increase in GC cell viability induced by senescent CAFs and peritoneal tumor formation. Single-cell mass cytometry revealed that fibroblasts exist in the ascites of GC patients with peritoneal dissemination, and the fibroblast population shows p16 expression and SASP factors at high levels. These findings provide insights into the inflammation-related SASP maintenance by histone modification and the role of senescent CAFs in GC peritoneal dissemination.

DOI： 10.1016/j.celrep.2021.108779

Overexpression of Hmga2 activates Igf2bp2 and remodels transcriptional program of Tet2-deficient stem cells in myeloid transformation. 査読国際誌

Jie Bai, Takako Yokomizo-Nakano, Sho Kubota, Yuqi Sun, Akinori Kanai, Mihoko Iimori, Hironori Harada, Atsushi Iwama, Goro Sashida

Oncogene 40 ( 8 ) 1531 - 1541 2021年2月

記述言語：英語掲載種別：研究論文（学術雑誌）

High Mobility Group AT-hook 2 (HMGA2) is a chromatin modifier and its overexpression has been found in patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Level of Hmga2 expression is fine-tuned by Lin28b-Let-7 axis and Polycomb Repressive Complex 2, in which deletion of Ezh2 leads to activation of Hmga2 expression in hematopoietic stem cells. To elucidate the mechanisms by which the overexpression of HMGA2 helps transformation of stem cells harboring a driver mutation of TET2, we generated an Hmga2-expressing Tet2-deficient mouse model showing the progressive phenotypes of MDS and AML. The overexpression of Hmga2 remodeled the transcriptional program of Tet2-deficient stem and progenitor cells, leading to the impaired differentiation of myeloid cells. Furthermore, Hmga2 was bound to a proximal region of Igf2bp2 oncogene, and activated its transcription, leading to enhancing self-renewal of Tet2-deficient stem cells that was suppressed by inhibition of the DNA binding of Hmga2. These combinatory effects on the transcriptional program and cellular function were not redundant to those in Tet2-deficient cells. The present results elucidate that Hmga2 targets key oncogenic pathways during the transformation and highlight the Hmga2-Igf2bp2 axis as a potential target for therapeutic intervention.

DOI： 10.1038/s41388-020-01629-w

Src-mediated tyrosine phosphorylation of PRC1 and kinastrin/SKAP on the mitotic spindle. 査読国際誌

Mariko Morii, Sho Kubota, Chizu Hasegawa, Yumi Takeda, Shiori Kometani, Kyoko Enomoto, Takayuki Suzuki, Sayuri Yanase, Rika Sato, Aki Akatsu, Kensuke Hirata, Takuya Honda, Takahisa Kuga, Takeshi Tomonaga, Yuji Nakayama, Noritaka Yamaguchi, Naoto Yamaguchi

Scientific reports 11 ( 1 ) 2616 - 2616 2021年1月

記述言語：英語掲載種別：研究論文（学術雑誌）

Src-family tyrosine kinases (SFKs) play important roles in a number of signal transduction events during mitosis, such as spindle formation. A relationship has been reported between SFKs and the mitotic spindle; however, the underlying mechanisms remain unclear. We herein demonstrated that SFKs accumulated in the centrosome region at the onset of mitosis. Centrosomal Fyn increased in the G2 phase in a microtubule polymerization-dependent manner. A mass spectrometry analysis using mitotic spindle preparations was performed to identify tyrosine-phosphorylated substrates. Protein regulator of cytokinesis 1 (PRC1) and kinastrin/small kinetochore-associated protein (kinastrin/SKAP) were identified as SFK substrates. SFKs mainly phosphorylated PRC1 at Tyr-464 and kinastrin at Tyr-87. Although wild-type PRC1 is associated with microtubules, phosphomimetic PRC1 impaired the ability to bind microtubules. Phosphomimetic kinastrin at Tyr-87 also impaired binding with microtubules. Collectively, these results suggest that tyrosine phosphorylation of PRC1 and kinastrin plays a role in their delocalization from microtubules during mitosis.

DOI： 10.1038/s41598-021-82189-1

Calreticulin haploinsufficiency augments stem cell activity and is required for onset of myeloproliferative neoplasms in mice. 査読国際誌

Kotaro Shide, Takuro Kameda, Ayako Kamiunten, Yoshinori Ozono, Yuki Tahira, Takako Yokomizo-Nakano, Sho Kubota, Masaya Ono, Kazuhiko Ikeda, Masaaki Sekine, Keiichi Akizuki, Kenichi Nakamura, Tomonori Hidaka, Yoko Kubuki, Hisayoshi Iwakiri, Satoru Hasuike, Kenji Nagata, Goro Sashida, Kazuya Shimoda

Blood 136 ( 1 ) 106 - 118 2020年7月

記述言語：英語掲載種別：研究論文（学術雑誌）

Mutations in JAK2, myeloproliferative leukemia virus (MPL), or calreticulin (CALR) occur in hematopoietic stem cells (HSCs) and are detected in more than 80% of patients with myeloproliferative neoplasms (MPNs). They are thought to play a driver role in MPN pathogenesis via autosomal activation of the JAK-STAT signaling cascade. Mutant CALR binds to MPL, activates downstream MPL signaling cascades, and induces essential thrombocythemia in mice. However, embryonic lethality of Calr-deficient mice precludes determination of a role for CALR in hematopoiesis. To clarify the role of CALR in normal hematopoiesis and MPN pathogenesis, we generated hematopoietic cell-specific Calr-deficient mice. CALR deficiency had little effect on the leukocyte count, hemoglobin levels, or platelet count in peripheral blood. However, Calr-deficient mice showed some hematopoietic properties of MPN, including decreased erythropoiesis and increased myeloid progenitor cells in the bone marrow and extramedullary hematopoiesis in the spleen. Transplantation experiments revealed that Calr haploinsufficiency promoted the self-renewal capacity of HSCs. We generated CALRdel52 mutant transgenic mice with Calr haploinsufficiency as a model that mimics human MPN patients and found that Calr haploinsufficiency restored the self-renewal capacity of HSCs damaged by CALR mutations. Only recipient mice transplanted with Lineage-Sca1+c-kit+ cells harboring both CALR mutation and Calr haploinsufficiency developed MPN in competitive conditions, showing that CALR haploinsufficiency was necessary for the onset of CALR-mutated MPNs.

DOI： 10.1182/blood.2019003358

Low prevalence of the BCR-ABL1 fusion gene in a normal population in southern Sarawak. 査読

Jew Win Kuan, Anselm Ting Su, Siow Phing Tay, Isabel Lim Fong, Sho Kubota, Lela Su'ut, Motomi Osato, Goro Sashida

International journal of hematology 111 ( 2 ) 217 - 224 2020年2月

記述言語：英語掲載種別：研究論文（学術雑誌）

The BCR-ABL1 fusion gene is the driver mutation of Philadelphia chromosome-positive chronic myeloid leukemia (CML). Its expression level in CML patients is monitored by a real-time quantitative polymerase chain reaction defined by the International Scale (qPCRIS). BCR-ABL1 has also been found in asymptomatic normal individuals using a non-qPCRIS method. In the present study, we examined the prevalence of BCR-ABL1 in a normal population in southern Sarawak by performing qPCRIS for BCR-ABL1 with ABL1 as an internal control on total white blood cells, using an unbiased sampling method. While 146 of 190 (76.8%) or 102 of 190 (53.7%) samples showed sufficient amplification of the ABL1 gene at > 20,000 or > 100,000 copy numbers, respectively, in qPCRIS, one of the 190 samples showed amplification of BCR-ABL1 with positive qPCRIS of 0.0023% and 0.0032% in two independent experiments, the sequence of which was the BCR-ABL1 e13a2 transcript. Thus, we herein demonstrated that the BCR-ABL1 fusion gene is expected to be present in approximately 0.5-1% of normal individuals in southern Sarawak.

DOI： 10.1007/s12185-019-02768-x

Ascl1-induced Wnt11 regulates neuroendocrine differentiation, cell proliferation, and E-cadherin expression in small-cell lung cancer and Wnt11 regulates small-cell lung cancer biology. 査読国際誌

Yuki Tenjin, Shinji Kudoh, Sho Kubota, Tatsuya Yamada, Akira Matsuo, Younosuke Sato, Takaya Ichimura, Hirotsugu Kohrogi, Goro Sashida, Takuro Sakagami, Takaaki Ito

Laboratory investigation; a journal of technical methods and pathology 99 ( 11 ) 1622 - 1635 2019年11月

記述言語：英語

The involvement of Wnt signaling in human lung cancer remains unclear. This study investigated the role of Wnt11 in neuroendocrine (NE) differentiation, cell proliferation, and epithelial-to-mesenchymal transition (EMT) in human small-cell lung cancer (SCLC). Immunohistochemical staining of resected specimens showed that Wnt11 was expressed at higher levels in SCLCs than in non-SCLCs; 58.8% of SCLC, 5.2% of adenocarcinoma (ADC), and 23.5% of squamous cell carcinoma tissues stained positive for Wnt11. A positive relationship was observed between Achaete-scute complex homolog 1 (Ascl1) and Wnt11 expression in SCLC cell lines, and this was supported by transcriptome data from SCLC tissue. The expression of Wnt11 and some NE markers increased after the transfection of ASCL1 into the A549 ADC cell line. Knockdown of Ascl1 downregulated Wnt11 expression in SCLC cell lines. Ascl1 regulated Wnt11 expression via lysine H3K27 acetylation at the enhancer region of the WNT11 gene. Wnt11 controlled NE differentiation, cell proliferation, and E-cadherin expression under the regulation of Ascl1 in SCLC cell lines. The phosphorylation of AKT and p38 mitogen-activated protein kinase markedly increased after transfection of WNT11 into the SBC3 SCLC cell line, which suggests that Wnt11 promotes cell proliferation in SCLC cell lines. Ascl1 plays an important role in regulating the Wnt signaling pathway and is one of the driver molecules of Wnt11 in human SCLC. Ascl1 and Wnt11 may employ a cooperative mechanism to control the biology of SCLC. The present results indicate the therapeutic potential of targeting the Ascl1-Wnt11 signaling axis and support the clinical utility of Wnt11 as a biological marker in SCLC.

DOI： 10.1038/s41374-019-0277-y

Role for tyrosine phosphorylation of SUV39H1 histone methyltransferase in enhanced trimethylation of histone H3K9 via neuregulin-1/ErbB4 nuclear signaling 査読

Nakajo, H., Ishibashi, K., Aoyama, K., Kubota, S., Hasegawa, H., Yamaguchi, N., Yamaguchi, N.

Biochemical and Biophysical Research Communications 511 ( 4 ) 765 - 771 2019年4月

Desuppression of TGF-β signaling via nuclear c-Abl-mediated phosphorylation of TIF1γ/TRIM33 at Tyr-524, -610, and -1048 査読

Ryuzaburo Yuki, Takashi Tatewaki, Noritaka Yamaguchi, Kazumasa Aoyama, Takuya Honda, Sho Kubota, Mariko Morii, Ichiro Manabe, Takahisa Kuga, Takeshi Tomonaga, Naoto Yamaguchi

Oncogene 38 ( 5 ) 637 - 655 2018年9月

Ezh2 loss propagates hypermethylation at T cell differentiation-regulating genes to promote leukemic transformation. 査読国際誌

Changshan Wang, Motohiko Oshima, Daisuke Sato, Hirotaka Matsui, Sho Kubota, Kazumasa Aoyama, Yaeko Nakajima-Takagi, Shuhei Koide, Jun Matsubayashi, Makiko Mochizuki-Kashio, Takako Nakano-Yokomizo, Jie Bai, Toshitaka Nagao, Akinori Kanai, Atsushi Iwama, Goro Sashida

The Journal of clinical investigation 128 ( 9 ) 3872 - 3886 2018年8月

記述言語：英語掲載種別：研究論文（学術雑誌）

Early T cell precursor acute lymphoblastic leukemia (ETP-ALL) is a new pathological entity with poor outcomes in T cell ALL (T-ALL) that is characterized by a high incidence of loss-of-function mutations in polycomb repressive complex 2 (PRC2) genes. We generated a mouse model of ETP-ALL by deleting Ezh2, one of the PRC2 genes, in p53-null hematopoietic cells. The loss of Ezh2 in p53-null hematopoietic cells impeded the differentiation of ETPs and eventually induced ETP-ALL-like disease in mice, indicating that PRC2 functions as a bona fide tumor suppressor in ETPs. A large portion of PRC2 target genes acquired DNA hypermethylation of their promoters following reductions in H3K27me3 levels upon the loss of Ezh2, which included pivotal T cell differentiation-regulating genes. The reactivation of a set of regulators by a DNA-demethylating agent, but not the transduction of single regulator genes, effectively induced the differentiation of ETP-ALL cells. Thus, PRC2 protects key T cell developmental regulators from DNA hypermethylation in order to keep them primed for activation upon subsequent differentiation phases, while its insufficiency predisposes ETPs to leukemic transformation. These results revealed a previously unrecognized epigenetic switch in response to PRC2 dysfunction and provide the basis for specific rational epigenetic therapy for ETP-ALL with PRC2 insufficiency.

DOI： 10.1172/JCI94645

Src Acts as an Effector for Ku70-dependent Suppression of Apoptosis through Phosphorylation of Ku70 at Tyr-530 査読

Mariko Morii, Sho Kubota, Takuya Honda, Ryuzaburo Yuki, Takao Morinaga, Takahisa Kuga, Takeshi Tomonaga, Noritaka Yamaguchi, Naoto Yamaguchi

JOURNAL OF BIOLOGICAL CHEMISTRY 292 ( 5 ) 1648 - 1665 2017年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Src-family tyrosine kinases are widely expressed in many cell types and participate in a variety of signal transduction pathways. Despite the significance of Src in suppression of apoptosis, its mechanism remains poorly understood. Here we show that Src acts as an effector for Ku70-dependent suppression of apoptosis. Inhibition of endogenous Src activity promotes UV-induced apoptosis, which is impaired by Ku70 knockdown. Src phosphorylates Ku70 at Tyr-530, being close to the possible acetylation sites involved in promotion of apoptosis. Src-mediated phosphorylation of Ku70 at Tyr-530 decreases acetylation of Ku70, whereas Src inhibition augments acetylation of Ku70. Importantly, knockdown-rescue experiments with stable Ku70 knockdown cells show that the nonphosphorylatable Y530F mutant of Ku70 reduces the ability of Ku70 to suppress apoptosis accompanied by augmentation of Ku70 acetylation. Our results reveal that Src plays a protective role against hyperactive apoptotic cell death by reducing apoptotic susceptibility through phosphorylation of Ku70 at Tyr-530.

DOI： 10.1074/jbc.M116.753202

c-Abl-mediated Tyrosine Phosphorylation of JunB is Required for Adriamycin-induced Expression of p21. 査読

Noritaka Yamaguchi, Ryuzaburo Yuki, Sho Kubota, Kazumasa Aoyama, Takahisa Kuga, Yuuki Hashimoto, Takeshi Tomonaga, Naoto Yamaguchi

The Biochemical journal 471 ( 1 ) 67 - 77 2015年10月

Src family kinases maintain the balance between replication stress and the replication checkpoint 査読

Takahito Miura, Yasunori Fukumoto, Mariko Morii, Takuya Honda, Noritaka Yamaguchi, Yuji Nakayama, Naoto Yamaguchi

Cell Biology International 40 ( 1 ) 16 - 26 2015年8月

Imatinib inhibits inactivation of the ATM/ATR signaling pathway and recovery from adriamycin/doxorubicin-induced DNA damage checkpoint arrest 査読

Mariko Morii, Yasunori Fukumoto, Sho Kubota, Noritaka Yamaguchi, Yuji Nakayama, Naoto Yamaguchi

CELL BIOLOGY INTERNATIONAL 39 ( 8 ) 923 - 932 2015年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-BLACKWELL

The DNA damage checkpoint arrests cell cycle progression to allow time for DNA repair. After completion of DNA repair, checkpoint activation is terminated, and cell cycle progression is resumed in a process called checkpoint recovery. The activation of the checkpoint has been studied in depth, but little is known about recovery from the DNA damage checkpoint. Recently we showed that Src family kinases promote recovery from the G2 DNA damage checkpoint. Here we show that imatinib inhibits inactivation of ATM/ATR signaling pathway to suppress recovery from Adriamycin/doxorubicin-induced DNA damage checkpoint arrest. Imatinib and pazopanib, two distinct inhibitors of PDGFR/c-Kit family kinases, delayed recovery from checkpoint arrest and inhibited the subsequent S-G2-M transition after Adriamycin exposure. By contrast, imatinib and pazopanib did not delay the recovery from checkpoint arrest in the presence of an ATM/ATR inhibitor caffeine. Consistently, imatinib induced a persistent activation of ATR-Chk1 signaling. By the way, the maintenance of G2 checkpoint arrest is largely dependent on ATR-Chk1 signaling. However, unlike Src inhibition, imatinib did not delay the recovery from checkpoint arrest in the presence of an ATM inhibitor KU-55933. Furthermore, imatinib induced a persistent activation of ATM-KAP1 signaling, and a possible involvement of imatinib in an ATM-dependent DNA damage response is suggested. These results reveal that imatinib inhibits recovery from Adriamycin-induced DNA damage checkpoint arrest in an ATM/ATR-dependent manner and raise the possibility that imatinib may inhibit resumption of tumor proliferation after chemo- and radiotherapy.

DOI： 10.1002/cbin.10460

Overexpression of Zinc-Finger Protein 777 (ZNF777) Inhibits Proliferation at Low Cell Density Through Down-Regulation of FAM129A. 査読

Ryuzaburo Yuki, Kazumasa Aoyama, Sho Kubota, Noritaka Yamaguchi, Shoichi Kubota, Hitomi Hasegawa, Mariko Morii, Xiayu Huang, Kang Liu, Roy Williams, Michiko N. Fukuda, Naoto Yamaguchi

Journal of cellular biochemistry 116 ( 6 ) 954 - 968 2015年6月

c-Abl induces stabilization of histone deacetylase 1 (HDAC1) in a kinase activity-dependent manner 査読

Kazumasa Aoyama, Noritaka Yamaguchi, Ryuzaburo Yuki, Mariko Morii, Sho Kubota, Kensuke Hirata, Kohei Abe, Takuya Honda, Takahisa Kuga, Yuuki Hashimoto, Takeshi Tomonaga, Naoto Yamaguchi

39 ( 4 ) 446 - 456 2015年1月

Lyn tyrosine kinase promotes silencing of ATM-dependent checkpoint signaling during recovery from DNA double-strand breaks 査読

Yasunori Fukumoto, Kazumasa Kuki, Mariko Morii, Takahito Miura, Takuya Honda, Kenichi Ishibashi, Hitomi Hasegawa, Sho Kubota, Yudai Ide, Noritaka Yamaguchi, Yuji Nakayama, Naoto Yamaguchi

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 452 ( 3 ) 542 - 547 2014年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE

DNA damage activates the DNA damage checkpoint and the DNA repair machinery. After initial activation of DNA damage responses, cells recover to their original states through completion of DNA repair and termination of checkpoint signaling. Currently, little is known about the process by which cells recover from the DNA damage checkpoint, a process called checkpoint recovery. Here, we show that Src family kinases promote inactivation of ataxia telangiectasia mutated (ATM)-dependent checkpoint signaling during recovery from DNA double-strand breaks. Inhibition of Src activity increased ATM-dependent phosphorylation of Chk2 and Kap1. Src inhibition increased ATM signaling both in G2 phase and during asynchronous growth. shRNA knockdown of Lyn increased ATM signaling. Src-dependent nuclear tyrosine phosphorylation suppressed ATM-mediated Kap1 phosphorylation. These results suggest that Src family kinases are involved in upstream signaling that leads to inactivation of the ATM-dependent DNA damage checkpoint. (C)2014 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2014.08.113

v-Src inhibits the interaction between Rad17 and Rad9 and induces replication fork collapse 査読

Yasunori Fukumoto, Takahito Miura, Mariko Morii, Sho Kubota, Takuya Honda, Shoichi Kubota, Takao Morinaga, Noritaka Yamaguchi, Yuji Nakayama, Naoto Yamaguchi

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 450 ( 1 ) 885 - 890 2014年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE

ATR-dependent DNA damage checkpoint is crucial to maintain genomic stability. Recently, we showed that Src family kinases suppress ATR-dependent checkpoint signaling in termination of DNA damage checkpoint. However, the precise molecular mechanism is unclear. Therefore, we examined the role of oncogenic v-Src on ATR-Chk1 signaling. We show that v-Src suppresses thymidine-induced Chk1 phosphorylation and induces replication fork collapse. v-Src inhibits interaction between Rad17 and Rad9 in chromatin fraction. By contrast, v-Src does not inhibit RPA32 phosphorylation, ATR autophosphorylation, or TopBP1-Rad9 interaction. These data suggest that v-Src attenuates ATR-Chk1 signaling through the inhibition of Radl7-Rad9 interaction. (C) 2014 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2014.06.078

Src Family Kinases Promote Silencing of ATR-Chk1 Signaling in Termination of DNA Damage Checkpoint 査読

Yasunori Fukumoto, Mariko Morii, Takahito Miura, Sho Kubota, Kenichi Ishibashi, Takuya Honda, Aya Okamoto, Noritaka Yamaguchi, Atsushi Iwama, Yuji Nakayama, Naoto Yamaguchi

JOURNAL OF BIOLOGICAL CHEMISTRY 289 ( 18 ) 12313 - 12329 2014年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Background: Once DNA repair is completed, the DNA damage checkpoint is terminated, and the cell cycle is resumed. Results: Src inhibition induced a delay in G(2) checkpoint recovery and persistent ATR-Chk1 activation. Conclusion: Src inhibits ATR signaling to promote recovery from G(2) checkpoint arrest. Significance: Src sends a termination signal between the completion of DNA repair and the initiation of checkpoint termination.
The DNA damage checkpoint arrests cell cycle progression to allow time for repair. Once DNA repair is completed, checkpoint signaling is terminated. Currently little is known about the mechanism by which checkpoint signaling is terminated, and the disappearance of DNA lesions is considered to induce the end of checkpoint signaling; however, here we show that the termination of checkpoint signaling is an active process promoted by Src family tyrosine kinases. Inhibition of Src activity delays recovery from the G(2) phase DNA damage checkpoint following DNA repair. Src activity is required for the termination of checkpoint signaling, and inhibition of Src activity induces persistent activation of ataxia telangiectasia mutated (ATM)- and Rad3-related (ATR) and Chk1 kinases. Src-dependent nuclear protein tyrosine phosphorylation and v-Src expression suppress the ATR-mediated Chk1 and Rad17 phosphorylation induced by DNA double strand breaks or DNA replication stress. Thus, Src family kinases promote checkpoint recovery through termination of ATR- and Chk1-dependent G(2) DNA damage checkpoint. These results suggest a model according to which Src family kinases send a termination signal between the completion of DNA repair and the initiation of checkpoint termination.

DOI： 10.1074/jbc.M113.533752

Activation of the Prereplication Complex Is Blocked by Mimosine through Reactive Oxygen Species-activated Ataxia Telangiectasia Mutated (ATM) Protein without DNA Damage 査読

Shoichi Kubota, Yasunori Fukumoto, Kenichi Ishibashi, Shuhei Soeda, Sho Kubota, Ryuzaburo Yuki, Yuji Nakayama, Kazumasa Aoyama, Noritaka Yamaguchi, Naoto Yamaguchi

JOURNAL OF BIOLOGICAL CHEMISTRY 289 ( 9 ) 5730 - 5746 2014年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Background: Mimosine is a cell synchronization reagent used for arresting cells in late G(1) and S phases. Results: Replication fork assembly is reversibly blocked by ATM activation through mimosine-generated reactive oxygen species. Conclusion: Mimosine induces cell cycle arrest strictly at the G(1)-S phase boundary, which prevents replication fork stalling-induced DNA damage. Significance: These findings provide a novel mechanism of the mimosine-induced G(1) checkpoint.
Mimosine is an effective cell synchronization reagent used for arresting cells in late G(1) phase. However, the mechanism underlying mimosine-induced G(1) cell cycle arrest remains unclear. Using highly synchronous cell populations, we show here that mimosine blocks S phase entry through ATM activation. HeLa S3 cells are exposed to thymidine for 15 h, released for 9 h by washing out the thymidine, and subsequently treated with 1 mm mimosine for a further 15 h (thymidine mimosine). In contrast to thymidine-induced S phase arrest, mimosine treatment synchronizes >90% of cells at the G(1)-S phase boundary by inhibiting the transition of the prereplication complex to the preinitiation complex. Mimosine treatment activates ataxia telangiectasia mutated (ATM)/ataxia telangiectasia and Rad3-related (ATR)-mediated checkpoint signaling without inducing DNA damage. Inhibition of ATM activity is found to induce mimosine-arrested cells to enter S phase. In addition, ATM activation by mimosine treatment is mediated by reactive oxygen species (ROS). These results suggest that, upon mimosine treatment, ATM blocks S phase entry in response to ROS, which prevents replication fork stalling-induced DNA damage.

DOI： 10.1074/jbc.M113.546655

Formation of long and winding nuclear F-actin bundles by nuclear c-Abl tyrosine kinase 査読

Kazumasa Aoyama, Ryuzaburo Yuki, Yasuyoshi Horiike, Sho Kubota, Noritaka Yamaguchi, Mariko Morii, Kenichi Ishibashi, Yuji Nakayama, Takahisa Kuga, Yuuki Hashimoto, Takeshi Tomonaga, Naoto Yamaguchi

Experimental Cell Research 319 ( 20 ) 3251 - 3268 2013年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Elsevier BV

The non-receptor-type tyrosine kinase c-Abl is involved in actin dynamics in the cytoplasm. Having three nuclear localization signals (NLSs) and one nuclear export signal, c-Abl shuttles between the nucleus and the cytoplasm. Although monomeric actin and filamentous actin (F-actin) are present in the nucleus, little is known about the relationship between c-Abl and nuclear actin dynamics. Here, we show that nuclear-localized c-Abl induces nuclear F-actin formation. Adriamycin-induced DNA damage together with leptomycin B treatment accumulates c-Abl into the nucleus and increases the levels of nuclear F-actin. Treatment of c-Abl-knockdown cells with Adriamycin and leptomycin B barely increases the nuclear F-actin levels. Expression of nuclear-targeted c-Abl (NLS-c-Abl) increases the levels of nuclear F-actin even without Adriamycin, and the increased levels of nuclear F-actin are not inhibited by inactivation of Abl kinase activity. Intriguingly, expression of NLS-c-Abl induces the formation of long and winding bundles of F-actin within the nucleus in a c-Abl kinase activity-dependent manner. Furthermore, NLS-c-AblδC, which lacks the actin-binding domain but has the full tyrosine kinase activity, is incapable of forming nuclear F-actin and in particular long and winding nuclear F-actin bundles. These results suggest that nuclear c-Abl plays critical roles in actin dynamics within the nucleus. © 2013 Elsevier Inc.

DOI： 10.1016/j.yexcr.2013.09.003

Nuclear ErbB4 signaling through H3K9me3 is antagonized by EGFR-activated c-Src 査読

Kenichi Ishibashi, Yasunori Fukumoto, Hitomi Hasegawa, Kohei Abe, Shoichi Kubota, Kazumasa Aoyama, Sho Kubota, Yuji Nakayama, Naoto Yamaguchi

JOURNAL OF CELL SCIENCE 126 ( 2 ) 625 - 637 2013年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：COMPANY OF BIOLOGISTS LTD

The ErbB family of receptor tyrosine kinases comprises four members: epidermal growth factor receptor (EGFR)/ErbB1, HER2/ErbB2, ErbB3 and ErbB4, and plays roles in signal transduction at the plasma membrane upon ligand stimulation. Stimulation with neuregulin-1 (NRG-1) cleaves ErbB4 and releases the ErbB4 intracellular domain (4ICD) that translocates into the nucleus to control gene expression. However, little is known about the regulation of 4ICD nuclear signaling through tyrosine phosphorylation. We show here that 4ICD nuclear signaling is antagonized by EGF-induced c-Src activation through EGFR. Generation of 4ICD by NRG-1 leads to increased levels of trimethylated histone H3 on lysine 9 (H3K9me3) in a manner dependent on the nuclear accumulation of 4ICD and its tyrosine kinase activity. Once EGF activates c-Src downstream of EGFR concomitantly with NRG-1-induced ErbB4 activation, c-Src associates with phospho-Tyr950 and phospho-Tyr1056 on 4ICD, thereby decreasing nuclear accumulation of 4ICD and inhibiting an increase of H3K9me3 levels. Moreover, 4ICD-induced transcriptional repression of the human telomerase reverse transcriptase (hTERT) is inhibited by EGF-EGFR-Src signaling. Thus, our findings reveal c-Src-mediated inhibitory regulation of ErbB4 nuclear signaling upon EGFR activation.

DOI： 10.1242/jcs.116277

Nuclear c-Abl-mediated tyrosine phosphorylation induces chromatin structural changes through histone modifications that include H4K16 hypoacetylation 査読

Kazumasa Aoyama, Yasunori Fukumoto, Kenichi Ishibashi, Sho Kubota, Takao Morinaga, Yasuyoshi Horiike, Ryuzaburo Yuki, Akinori Takahashi, Yuji Nakayama, Naoto Yamaguchi

EXPERIMENTAL CELL RESEARCH 317 ( 20 ) 2874 - 2903 2011年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER INC

c-Abl tyrosine kinase, which is ubiquitously expressed, has three nuclear localization signals and one nuclear export signal and can shuttle between the nucleus and the cytoplasm. c-Abl plays important roles in cell proliferation, adhesion, migration, and apoptosis. Recently, we developed a pixel imaging method for quantitating the level of chromatin structural changes and showed that nuclear Src-family tyrosine kinases are involved in chromatin structural changes upon growth factor stimulation. Using this method, we show here that nuclear c-Abl induces chromatin structural changes in a manner dependent on the tyrosine kinase activity. Expression of nuclear-targeted c-Abl drastically increases the levels of chromatin structural changes, compared with that of c-Abl. Intriguingly, nuclear-targeted c-Abl induces heterochromatic profiles of histone methylation and acetylation, including hypoacetylation of histone H4 acetylated on lysine 16 (H4K16Ac). The level of heterochromatic histone modifications correlates with that of chromatin structural changes. Adriamycin-induced DNA damage stimulates translocation of c-Abl into the nucleus and induces chromatin structural changes together with H4K16 hypoacetylation. Treatment with trichostatin A, a histone deacetylase inhibitor, blocks chromatin structural changes but not nuclear tyrosine phosphorylation by c-Abl. These results suggest that nuclear c-Abl plays an important role in chromatin dynamics through nuclear tyrosine phosphorylation-induced heterochromatic histone modifications. (C) 2011 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.yexcr.2011.09.013

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