Contribution of Dysferlin-Containing Membranes to Membrane Repair in Skeletal Muscle.

Membrane Repair in Skeletal Muscle;Physiology;Science;Molecular and Integrative Physiology

McDade, Joel RyanLopatin, Anatoli ;

University of Michigan

关键词: Membrane Repair in Skeletal Muscle;    Physiology;    Science;    Molecular and Integrative Physiology;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/107135/jmcdade_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The ability to repair the sarcolemma following injury is critical for muscle cells, and impaired membrane repair capacity is associated with inherited muscular dystrophy. Dysferlin is a membrane protein hypothesized to contribute to membrane repair by regulating vesicle-vesicle or vesicle-sarcolemma fusion, but the mechanism by which different dysferlin-containing membrane compartments contribute to membrane repair in skeletal muscle is unknown. While interactions between vesicles and the cytoskeleton may be involved in membrane resealing in non-muscle cells, whether interactions between dysferlin-containing membranes and the cytoskeleton are required for sarcolemma repair in muscle is unknown. Therefore, the goal of this thesis was to examine the mechanism by which dysferlin-containing compartments contribute to membrane repair in myotubes and adult muscle fibers, and test the overall hypothesis that dynamic interactions between dysferlin-containing membranes and the cytoskeleton are critical for membrane resealing in skeletal muscle. Live-cell imaging of dysferlin-eGFP expressing myotubes or dysferlin-pHGFP expressing myofibers isolated from a novel transgenic reporter mouse were used to explore the dynamic behavior of dysferlin-containing membranes at rest and during membrane repair. Dysferlin localizes primarily to intracellular vesicles that interact directly with microtubules in developing myotubes, but is restricted largely to the plasma membrane and t-tubules in mature adult skeletal muscle fibers. Mechanical wounding of myotubes induces rapid microtubule-dependent vesicle-vesicle fusion to form large dysferlin-containing vesicles which may plug large lesions. Interestingly, sarcolemma wounding in adult fibers induces formation of large vesicles by endocytosis, but more prominently rapid actin-dependent recruitment of sarcolemma-derived dysferlin to wounds. Dysferlin recruitment results in the formation of stable dysferlin-rich regions surrounding the lesion, and is required for membrane resealing, potentially by concentrating the lipid-binding function of dysferlin specifically at lesions. In summary, this thesis work shows that dysferlin localizes to specific damage-responsive membrane compartments in muscle, and demonstrates that interactions between dysferlin-containing membranes and the intracellular cytoskeleton is essential for dysferlin function in membrane repair. The transgenic reporter mouse described here will also be a valuable tool for future studies into the mechanisms of dysferlin-mediated membrane repair in normal muscle injury and inherited muscle diseases.