Myristoylated alanine-rich C kinase substrate (MARCKS) is involved in myoblast fusion through its regulation by protein kinase Calpha and calpain proteolytic cleavage.
MARCKS (myristoylated alanine-rich C kinase substrate) is a major cytoskeletal protein substrate of PKC (protein kinase C) whose cellular functions are still unclear. However numerous studies have implicated MARCKS in the stabilization of cytoskeletal structures during cell differentiation. The present study was performed to investigate the potential role of Ca(2+)-dependent proteinases (calpains) during myogenesis via proteolysis of MARCKS. It was first demonstrated that MARCKS is a calpain substrate in vitro. Then, the subcellular expression of MARCKS was examined during the myogenesis process. Under such conditions, there was a significant decrease in MARCKS expression associated with the appearance of a 55 kDa proteolytic fragment at the time of intense fusion. The addition of calpastatin peptide, a specific calpain inhibitor, induced a significant decrease in the appearance of this fragment. Interestingly, MARCKS proteolysis was dependent of its phosphorylation by the conventional PKCalpha. Finally, ectopic expression of MARCKS significantly decreased the myoblast fusion process, while reduced expression of the protein with antisense oligonucleotides increased the fusion. Altogether, these data demonstrate that MARCKS proteolysis is necessary for the fusion of myoblasts and that cleavage of the protein by calpains is involved in this regulation.
Dulong
Sandrine
S
Laboratoire Biosciences de l'Aliment, Université Bordeaux I, ISTAB (L'Institut des Sciences et Techniques des Aliments de Bordeaux), USC-2009, Avenue des Facultés, 33405 Talence cedex, France.
Goudenege
Sebastien
S
Vuillier-Devillers
Karine
K
Manenti
Stéphane
S
Poussard
Sylvie
S
Cottin
Patrick
P
D000818:Animals; D002154:Calpain / Q000378:metabolism*; D002459:Cell Fusion; D002460:Cell Line; D003599:Cytoskeleton / Q000502:physiology; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism / Q000502:physiology*; D008565:Membrane Proteins / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D024510:Muscle Development / Q000502:physiology; D032446:Myoblasts / Q000502:physiology*; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D011493:Protein Kinase C / Q000378:metabolism*; D051571:Protein Kinase C-alpha; D011994:Recombinant Proteins / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism
D047908:Intracellular Signaling Peptides and Proteins; C000619711:Marcks protein, mouse; D008565:Membrane Proteins; D011994:Recombinant Proteins; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; C496630:Prkca protein, mouse; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D002154:Calpain