The caveolin-cavin system plays a conserved and critical role in mechanoprotection of skeletal muscle.
Bottom Line: Caveolae occupied around 50% of the sarcolemmal area predominantly assembled into multilobed rosettes.These rosettes were preferentially disassembled in response to increased membrane tension.Our findings define a conserved and critical role in mechanoprotection for the unique membrane architecture generated by the caveolin-cavin system.
Affiliation: Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.Show MeSH
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Mentions: We further analyzed the organization of the ruthenium red–labeled WT and cavin-1−/− muscle fibers by electron tomography. In WT muscle fibers, T-tubules invariably connected to the muscle fiber surface via surface-connected caveolae (Fig. 3, A–G; and Videos 2 and 3). Surface-rendered reconstruction of the T-tubule system clearly demonstrated the connection of the T-tubule system to the surface via caveolar rosettes (Fig. 3 H). A similar 3D analysis of cavin-1−/− muscle fibers highlighted the abnormal and dilated T-tubule network within the muscle fiber as well as the surface-connected vacuoles (Fig. 3, I–L; and Video 4). In the absence of caveolae, the abnormal T-tubule network connected to the surface of the muscle fiber via the abundant vacuoles (Video 5). The reticular networks observed in thin sections throughout the cavin-1−/− muscle could be shown to be highly complex “honeycomb-like” reticulated networks with multiple connections to the cell surface via large vacuoles (Fig. 3, M–O; and Fig. S3, A and B) and connections to the T-tubule network, including triad junctions (Fig. S1 A).
Affiliation: Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.