Annexin A1 (ANXA1) is a calcium- and phospholipid-binding protein involved in a broad range of cellular events. This study used molecular and microscopy approaches to explore the role of ANXA1 in mouse myoblast C2C12 cell differentiation. We report that ANXA1 expression increases during differentiation and that the down-regulation of ANXA1 significantly inhibits the differentiation process. ANXA1 is expressed in vivo in both quiescent and activated satellite cells and is highly localized in the cells that migrate in the lumen of regenerating fibers after an acute injury. Endogenous ANXA1 co-localizes with actin fibers at the protruding ends of undifferentiated but not differentiated cells suggesting a role of the protein in cell migration. Furthermore, ANXA1 neutralizing antibody reduces MyHC expression, decreases myotube formation and significantly inhibits cell migration. The data reported here suggest for the first time that ANXA1 plays a role in myogenic differentiation.
(c) 2010 Wiley-Liss, Inc.