1997 Fiscal Year Final Research Report Summary
Expression of myogenic factors and muscle proteins during myofibrillogenesis
| Project/Area Number |
07670004
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General anatomy (including Histology/Embryology)
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| Research Institution | Chiba University |
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Principal Investigator |
TOYOTA Naoji Chiba Univ.Sch.Med.Anatomy Lecturer, 医学部, 講師 (00188822)
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| Co-Investigator(Kenkyū-buntansha) |
KOMIYAMA Masatoshi Chiba Univ.Sch.Med.Mol.Biol.Assistant, 医学部, 助手 (70175339)
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| Project Period (FY) |
1995 – 1997
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| Keywords | myogenic factors / in situ hybridization / tag / troponin / force-expression / c-myc |
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| Research Abstract |
We studied gene expression of myogenic factors (Myf-5, myogenin and MyoD) by whole mount in situ hybridization. Expression of Myf-5, myogenin and MyoD genes were found in somites of chicken embtyo at stage 7-8,10 and 9-10, respectively. These stages observed in this study were earlier than those repoted by others and the order of these expression was the same as those presented by others.
The isoform-specific assembly of cardiac and fast skeletal muscle troponin I (CTnland FTnI,respectively) to myofibrils (MFs) of respective muscles was investigated. Epitope tagging was used to monitor the intracellular localization of the exogenously introduced constructs to myofibrillar structures in cultured chicken cardiac and breast (fast) muscle cells. Exogenous CTnl and FTnl were incorporated into endogenous MFs of cardiac and breast muscle cells, respectively. In the case of CTnl and FTnl with breast and cardiac muscle cells respectively, FTnl was assembled onto cardiac MFs but CTnl was not incorporated into breast MFs. To determine which portion of CTnl is responsible for sorting this protein from breast MFs, we constructed chimeric Tnls with the CTnI-head or-tail replaced with those of FTnI.The behavior of the chimera constructed with FTnI-head and CTnI-tail was similar to that of CTnI,with the tail portion being important for the sorting mechanism. Truncated TnI-heads and -tails were also prepared, and their assembly onto MFs was examined. The results also showed that TnI-tail is important for the specific incorporation into MFs.
These results suggest that each myofibrillar proteins have unique binding affinity distinct from other isoforms. The binding affinity plays an important role in the proper assembly of functional muscle cell structures during myogenesis.
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[Publications] Begum, S., Komiyama, M., Toyota, N., Obinata, T., Maruyama, K.and Shimada, Y.: "Differentiation of muscle-specific proteins in chicken somites as studied by immunofluorescence microscopy." Cell Tissue Res.(in press).
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