論文 - 佐藤　伸

Nerve-dependent and -independent events in blastema formation during Xenopus froglet limb regeneration 査読

M Suzuki, A Satoh, H Ide, K Tamura

DEVELOPMENTAL BIOLOGY   286 ( 1 )   361 - 375   2005年10月

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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  

Blastema formation, the initial stage of epimorphic limb regeneration in amphibians, is an essential process to produce regenerates. In our study on nerve dependency of blastema fort-nation, we used forelimb of Xenopus laevis froglets as a system and applied some histological and molecular approaches in order to determine early events during blastema formation. We also investigated the lateral wound healing in comparison to blastema formation in limb regeneration. Our study confirmed at the molecular level that there are nerve-dependent and -independent events during blastema formation after limb amputation, Tbx5 and Pryl, reliable markers of initiation of limb regeneration, that start to be expressed independently of nerve supply, although their expressions cannot be maintained without nerve supply. We also found that cell proliferation activity, cell survival and expression of Fgf8, Fgf10 and Msxl in the blastema were affected by denervation, suggesting that these events specific for blastema outgrowth are controlled by the nerve supply. Wound healing, which is thought to be categorized into tissue regeneration, shares some nerve-independent events with epimorphic limb regeneration, although the healing process results in simple restoration of wounded tissue. Overall, our results demonstrate that dedifferentiated blastemal cells formed at the initial phase of limb regeneration must enter the nerve-dependent epimorphic phase for further processes, including blastema outgrowth, and that failure of entry results in a simple redifferentiation as tissue regeneration. (c) 2005 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.ybio.2005.08.021

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Joint development in Xenopus laevis and induction of segmentations in regenerating froglet limb (spike) 査読

A Satoh, M Suzuki, T Amano, K Tamura, H Ide

DEVELOPMENTAL DYNAMICS   233 ( 4 )   1444 - 1453   2005年8月

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担当区分：筆頭著者   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-LISS  

In Xenopus laevis, amputation of the adult limb results in the formation of a simple (hypomorphic) spike-like structure without joints, although tadpole limb bud regenerates complete limb pattern. The expression of some joint marker genes was examined in limb development and regeneration. Bmp center dot 4 and gdf center dot 5 were expressed and sox-9 expression was decreased in the joint region. Although developing cartilages were well-organized and had bmp-4 expressing perichondrocytes, the spike cartilage did not have such a structure, but only showed sparse bmp-4 expression. Application of BMP4-soaked beads to the spike led to the induction of a joint-like structure. These results suggest that the lack of joints in the spike is due to the deficiency of the accumulation of the cells that express bmp-4. Improvement of regeneration in the Xenopus adult limb that we report here for the first time will give us important insights into epimorphic regeneration. (c) 2005 Wiley-Liss, Inc.

DOI： 10.1002/dvdy.20484

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Muscle formation in regenerating Xenopus froglet limb 査読

A Satoh, H Ide, K Tamura

DEVELOPMENTAL DYNAMICS   233 ( 2 )   337 - 346   2005年6月

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担当区分：筆頭著者   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-LISS  

A spike, a resultant regenerate made after amputation of a Xenopus froglet limb, has no muscle tissue. This muscle-less phenotype was analyzed by molecular approaches, and the results of analysis revealed that the spike expresses no myosin heavy chain or Pax7, suggesting that neither mature muscle tissue nor satellite cells exist in the spike. The regenerating blastema in the froglet limb lacked some myogenesis-related marker genes, myoD and myf5, but allowed implanted muscle precursor cells to survive and differentiate into myofiber. Implantation of hepatocyte growth factor (HGF)-releasing cell aggregates rescued this muscle-less phenotype and induced muscle regeneration in Xenopus froglet limb regenerates. These results suggest that failure of regeneration of muscle is due to a disturbance of the early steps of myogenesis under a molecular cascade mediated by HGF/c-met. Improvement of muscle regeneration in the Xenopus adult limb that we report here for the first time will give us important insights into epimorphic tissue regeneration in amphibians and other vertebrates. (c) 2005 Wiley-Liss, Inc.

DOI： 10.1002/dvdy.20349

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