1996 Fiscal Year Final Research Report Summary
Ultrastructural basis of plasmalemma-cytoskeleton interaction
| Project/Area Number |
06454139
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | GUNMA UNIVERSITY SCHOOL OF MEDICINE |
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Principal Investigator |
ISHIKAWA Harunori Gunma University School of Medicine, Professor, 医学部, 教授 (90010058)
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| Co-Investigator(Kenkyū-buntansha) |
HIJIKATA Takao Gunma University School of Medicine, Assistant, 医学部, 助手 (70189786)
FUJIMAKI Noboru Gunma University School of Medicine, Lecturer, 医学部, 講師 (10008261)
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| Project Period (FY) |
1994 – 1996
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| Keywords | Plasmalemm / cytoskeleton / plasmalemmal undercoat / actin bundle / microtubule / electron microscopy / ジストロフィン / ラミニン |
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| Research Abstract |
The present research project was to elucidate the ultrastructural and molecular organization of the association of cytoskeletal components to the plasmalemma and the involvement of plasmalemmal undercoat to such an association. The results obtained were as follows.
1) Occurrence of fasciculated microtubules at the nodes of Ranvier
Fascicles of microtubules, previously considered to be unique to the initial segments of myelinated axons, were found at the nodes of Ranvier of sensory and motor axones in the rat spinal roots, though their occurrence was limited to the proximal portion of the axons. Microtubules in the fascicles were characteristically cross-linked by short filamentous strands at a center-to-center distance of 36-4Onm. These findings suggest that cross-linking proteins for fasciculation may be transported along the axon to fasciculate microtubules at some proximal nodes of Ranvier.
2) Actin bundles in epithelial cells of hair follicles
The whole-mount preparations of human grow
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ing hair follicles stained with fluorescent dye-labeled phalloidin were examined by confocal laser microscopy. As the results, it was shown that the innermost and outermost cell layers of the outer root sheath contained well developed bundles of actin filaments. The distribution and arrangement of such actin bundles varied in different parts of the hair follicle, but actin bundles were seen to be arranged circumferetial to the follicle axis. Ultrastructurally, bundles of actin filaments spanned the cytoplasm from one cell-cell adherens junction to another, thus forming multicellular networks of actin bundles. Actin bundles also contained myosin, alpha-actinin and vinculin. These findings suggest that actin bundles with their contractile property may be actively involved in hair follicle growth.
3) Structural array from dystrophin to laminin across the sarcolemma in skeletal muscle fibers
The relationship of dystrophin, dystroglycan complex and laminin was ultrastructurally and biochemically examined using crude sarcolemmal vesicles to elucidate the molecular array from dystrophin to laminin across the sarcolemma. Vesicles derived from the sarcolemma were well identified and used for the study of reassociation of exogenous laminin with the sarcolemma. Laminin molecules were specifically reassociated with the sarcolemmal vesicles through fine projections, which, could be shown to represent dystroglycan complexes. It was thus comfirmed ultrastructurally that dystrophin bound to dystroglycan complexes, with which laminin was associated, forming a molecular array from dystrophin to laminin through the sarcolemma. Less
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