Myoblast migration is regulated by calpain through its involvement in cell attachment and cytoskeletal organization.
Cell migration is a fundamental cellular function particularly during skeletal muscle development. Ubiquitous calpains are well known to play a pivotal role during muscle differentiation, especially at the onset of fusion. In this study, the possible positive regulation of myoblast migration by calpains, a crucial step required to align myoblasts to permit them to fuse, was investigated. Inhibition of calpain activity by different pharmacological inhibitors argues for the involvement of these proteinases during the migration of myoblasts. Moreover, a clonal cell line that fourfold overexpresses calpastatin, the endogenous inhibitor of calpains, and that exhibits deficient calpain activities was obtained. The results showed that the migratory capacity of C2C12 and fusion into multinucleated myotubes were completely prevented in these clonal cells. Calpastatin-overexpressing myoblasts unable to migrate were characterized by rounded morphology, the loss of membrane extensions, the disorganization of stress fibers and exhibited a major defect in new adhesion formation. Surprisingly, the proteolytic patterns of desmin, talin, vinculin, focal adhesion kinase (FAK) and ezrin, radixin, moesin (ERM) proteins are the same in calpastatin-overexpressing myoblasts as compared to control cells. However, an important accumulation of myristoylated alanine-rich C kinase substrate (MARCKS) was observed in cells showing a reduced calpain activity, suggesting that the proteolysis of this actin-binding protein is calpain-dependent and could be involved in both myoblast adhesion and migration.
Dedieu
Stéphane
S
Laboratoire Biosciences de l'Aliment, Université Bordeaux I, ISTAB USC INRA 429, 33405 Talence Cedex, France.
Poussard
Sylvie
S
Mazères
Germain
G
Grise
Florence
F
Dargelos
Elise
E
Cottin
Patrick
P
Brustis
Jean-Jacques
JJ
D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002154:Calpain / Q000037:antagonists & inhibitors* / Q000187:drug effects / Q000378:metabolism; D002448:Cell Adhesion; D002459:Cell Fusion; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D002999:Clone Cells; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003599:Cytoskeleton / Q000378:metabolism; D004151:Dipeptides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005959:Glucosidases; D047908:Intracellular Signaling Peptides and Proteins; D007976:Leupeptins / Q000494:pharmacology; D008565:Membrane Proteins; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D032446:Myoblasts / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D009842:Oligopeptides / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D022502:Stress Fibers / Q000187:drug effects / Q000378:metabolism
D002135:Calcium-Binding Proteins; D015853:Cysteine Proteinase Inhibitors; D004151:Dipeptides; D047908:Intracellular Signaling Peptides and Proteins; D007976:Leupeptins; C000619711:Marcks protein, mouse; D008565:Membrane Proteins; D009842:Oligopeptides; D010750:Phosphoproteins; C512949:Prkcsh protein, mouse; C069861:calpain inhibitor 2; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; C071482:calpeptin; C033668:calpastatin; D005959:Glucosidases; D002154:Calpain; C032854:leupeptin