title: Merosin-integrin promotion of skeletal myofiber cell survival: Differentiation state-distinct involvement of p60Fyn tyrosine kinase and p38alpha stress-activated MAP kinase.
abstract: Myofiber survival and suppression of anoikis depend in large part on the merosin (laminin-2/-4)-integrin alpha7beta1D cell adhesion system; however, the question remains as to the nature of the signaling molecules/pathways involved. In the present study, we investigated this question using the C2C12 cell model of myogenic differentiation and its merosin- and laminin-deficient derivatives. Herein, we report that: 1) of four members of the Src family of tyrosine kinases studied (p60Src, p53/56Lyn, p59Yes, or p60Fyn), the expression and activity of p60Fyn are found in myotubes exclusively; 2) a severe decrease of p60Fyn activity correlates with myotube apoptosis/anoikis induced by pharmocological compounds (herbimycin A or PP2) which inhibit tyrosine kinases of the Src family, by merosin deficiency and by beta1 integrin inhibition; 3) myoblast survival depends on Fak and the MEK/Erk pathway, in contrast to myotubes; 4) the PI3-K pathway is not involved in either myoblast or myotube survival; and 5) p38alpha SAPK stimulation and activity (but not that of p38beta) are required in the progression of myotube apoptosis/anoikis induced by p60Fyn inhibition, merosin deficiency or beta1 integrin-inhibition; however, p38 is not involved in myoblast apoptosis. Taken together, these results suggest that the promotion of myotube survival by the merosin-alpha7beta1D adhesion system involves p60Fyn, and that disruptions in this cell adhesion system induce myotube apoptosis/anoikis through a p38alpha SAPK-dependent pathway.
authors.affiliation: Département d'anatomie et de biologie cellulaire, Faculté de médecine, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Patrick
authors.initials: P
authors.lastname: Laprise
authors.forename: Eve-Marie
authors.initials: EM
authors.lastname: Poirier
authors.forename: Anne
authors.initials: A
authors.lastname: Vézina
authors.forename: Nathalie
authors.initials: N
authors.lastname: Rivard
authors.forename: Pierre H
authors.initials: PH
authors.lastname: Vachon
mesh_terms: D000818:Animals; D023102:Anoikis / Q000502:physiology; D017209:Apoptosis / Q000502:physiology; D016227:Benzoquinones; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D002470:Cell Survival / Q000502:physiology; D016023:Integrins / Q000502:physiology*; D047029:Lactams, Macrocyclic; D007797:Laminin / Q000172:deficiency / Q000502:physiology*; D051379:Mice; D048308:Mitogen-Activated Protein Kinase 14; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D051076:Proto-Oncogene Proteins c-fyn; D011809:Quinones / Q000494:pharmacology; D017828:Rifabutin / Q000031:analogs & derivatives; D015398:Signal Transduction / Q000502:physiology; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D016227:Benzoquinones; D016023:Integrins; D047029:Lactams, Macrocyclic; D007797:Laminin; D011518:Proto-Oncogene Proteins; D011809:Quinones; D017828:Rifabutin; C020754:herbimycin; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; D048308:Mitogen-Activated Protein Kinase 14; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases