title: p130Cas-dependent actin remodelling regulates myogenic differentiation.
abstract: Actin dynamics are implicated in various cellular processes, not only through the regulation of cytoskeletal organization, but also via the control of gene expression. In the present study we show that the Src family kinase substrate p130Cas (Cas is Crk-associated substrate) influences actin remodelling and concomitant muscle-specific gene expression, thereby regulating myogenic differentiation. In C2C12 myoblasts, silencing of p130Cas expression by RNA interference impaired F-actin (filamentous actin) formation and nuclear localization of the SRF (serum-response factor) co-activator MAL (megakaryocytic acute leukaemia) following the induction of myogenic differentiation. Consequently, formation of multinucleated myotubes was abolished. Re-introduction of wild-type p130Cas, but not its phosphorylation-defective mutant, into p130Cas-knockdown myoblasts restored F-actin assembly, MAL nuclear localization and myotube formation. Depletion of the adhesion molecule integrin β3, a key regulator of myogenic differentiation as well as actin cytoskeletal organization, attenuated p130Cas phosphorylation and MAL nuclear localization during C2C12 differentiation. Moreover, knockdown of p130Cas led to the activation of the F-actin-severing protein cofilin. The introduction of a dominant-negative mutant of cofilin into p130Cas-knockdown myoblasts restored muscle-specific gene expression and myotube formation. The results of the present study suggest that p130Cas phosphorylation, mediated by integrin β3, facilitates cofilin inactivation and promotes myogenic differentiation through modulating actin cytoskeleton remodelling.
authors.affiliation: Mechanobiology Institute, National University of Singapore, Level 10, T-Lab, 5A Engineering Drive 1, Singapore 117411.
authors.forename: Keiko
authors.initials: K
authors.lastname: Kawauchi
authors.forename: Wee Wee
authors.initials: WW
authors.lastname: Tan
authors.forename: Keigo
authors.initials: K
authors.lastname: Araki
authors.forename: Farhana Binte
authors.initials: FB
authors.lastname: Abu Bakar
authors.forename: Minsoo
authors.initials: M
authors.lastname: Kim
authors.forename: Hideaki
authors.initials: H
authors.lastname: Fujita
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Hirata
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Sawada
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D051340:Cofilin 2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D050719:Crk-Associated Substrate Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D039661:Integrin beta3 / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D024510:Muscle Development / Q000235:genetics / Q000502:physiology*; D016296:Mutagenesis; D032448:Myoblasts, Skeletal / Q000166:cytology* / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D000099200:Scaffold Protein ILK; D015534:Trans-Activators
chemical_list: D000199:Actins; D051340:Cofilin 2; D050719:Crk-Associated Substrate Protein; D017931:DNA Primers; D039661:Integrin beta3; D047908:Intracellular Signaling Peptides and Proteins; D017346:Protein Serine-Threonine Kinases; D000099200:Scaffold Protein ILK; C493842:Bcar1 protein, mouse; C486554:Tesk2 protein, mouse; C097507:testis-specific protein kinase 1; C511173:Mrtfa protein, mouse; D015534:Trans-Activators