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Microtubule‐dependent transport and organization of sarcomeric myosin during skeletal muscle differentiation
Author(s) -
Pizon Véronique,
Gerbal Fabien,
Diaz Carmen Cifuentes,
Karsenti Eric
Publication year - 2005
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600842
Subject(s) - sarcomere , myosin , microbiology and biotechnology , myogenesis , actin , microtubule , skeletal muscle , green fluorescent protein , biology , biophysics , myosin head , myocyte , chemistry , anatomy , myosin light chain kinase , biochemistry , gene
It has been proposed that microtubules (MTs) participate in skeletal muscle cell differentiation. However, it is still unclear how this happens. To examine whether MTs could participate directly in the organization of thick and thin filaments into sarcomeres, we observed the concomitant reorganization and dynamics of MTs with the behavior of sarcomeric actin and myosin by time‐lapse confocal microscopy. Using green fluorescent protein (GFP)‐EB1 protein to label MT plus ends, we determined that MTs become organized into antiparallel arrays along fusing myotubes. Their dynamics and orientation was found to be different across the thickness of the myotubes. We observed fast movements of Dsred‐myosin along GFP‐MTs. Comparison of GFP‐EB1 and Dsred‐myosin dynamics revealed that myosin moved toward MT plus ends. Immuno‐electron microscopy experiments confirmed that myosin was actually associated with MTs in myotubes. Finally, we confirmed that MTs were required for the stabilization of myosin‐containing elements prior to incorporation into mature sarcomeres. Collectively, our results strongly suggest that MTs become organized into a scaffold that provides directional cues for the positioning and organization of myosin filaments during sarcomere formation.