1992 Fiscal Year Final Research Report Summary
Differentiation of contractile and cytoskeletal proteins and myofibril assembly in muscle cells.
| Project/Area Number |
02454109
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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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 |
SHIMADA Yutaka Chiba University, School of Medicine, Professor, 医学部, 教授 (70009116)
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| Co-Investigator(Kenkyū-buntansha) |
KOMIYAMA Masatoshi Chiba University, School of Medicine, Research Associate, 医学部, 助手 (70175339)
TOYOTA Naoji Chiba University, School of Medicine, Instructor, 医学部, 講師 (00188822)
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| Project Period (FY) |
1990 – 1992
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| Keywords | Myofibrillogenesis / Connectin / Nebulin / Vinculin / Troponin / Sarcoplasmic reticulum / T system tubules / Intercellular junctions |
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| Research Abstract |
1. Myofibrillogenesis and cytoskeletion: Immunofluorescence microscopy of cultured muscle cells showed that (1) myofibril assembly is related with the accumulation of adhesion plaque proteins (vinculin and alpha-actinin) at the areas of focal contacts of cells with the substrate, (2) muscle giant proteins (connectin and nebulin) do not play any role in the initial formation of I-Z-I complexes of myofibrils, and (3) connectin plays some role in integrating myosin filaments with the preexisting I-Z-I brushes.
2. Actin dynamics during myofibrillogenesis: Immunogold electron microscopy of cardiomyocytes microinjected with biotin-labeled actin showed that injected actin associates with the A band level of myofibrils and along the extending direction of the myofibrillar terminals. This result indicates that polymerization of actin occurs preferentially in association with myosin filaments to increase the myofibrillar girth and that actin subunits are added at the membrane-associated ends of preexisting actin filaments to increase the length of myofibrils.
3. Gene expression of troponin C: Immunofluorescence microscopy, Northern blot analysis and S1 nuclease protection assay revealed that the expression of cardiac (embryonic) type troponin C gene in adult skeletal muscle is regulated posttranscriptionally.
4. Myofibrillogenesis and cytoplasmic organelles: (1) Electron microscopy of freeze-fracture-deep-etch replicas of cultured muscle revealed that T system tubules were formed from caveolae of the sarcolemma.(2) Intermediate voltage electron microscopy of thick sections of stretched muscle showed that sarcoplasmic reticulum was arranged periodically prior to the periodic alignment of T tubules and myofibrillar proteins. (3) Rapid freezing and freeze substitution of embryonic chick hearts showed that this method revealed junctional structures much more in detail than the chemically fixed materials.
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[Publications] Hastings, K.E.M., Koppe, R.I., Marmor, E., Bader, D., Shimada, Y. and Toyota, N.: "Structure and developmental expression of troponin I isoforms. cDNA clone analysis of avian cardiac troponin I mRNA." J. Biol. Chem. 266. 19659-19665 (1991)
Description
「研究成果報告書概要(欧文)」より
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