In nascent cultured primary chick skeletal myocytes, a l integrin is observed to have a punctate distribution. As early as day 3 in culture, however, it can be found to reorganize into periodic doublet bands. Subsequent to a l integrin reorganization, collagen type III has been found to colocalize with these periodic α l integrin bands. The coordinated appearance of these two proteins is suggestive of a possible regulatory role for one or both proteins in muscle development.
To ascertain whether this same αl integrin/collagen type III reorganization occurs in muscle cell lines, differentiating myocytes from the C2C12 cell line were examined for the temporal appearance and localization of both proteins. Cultured C2C12 cells were immunofluorescently labeled with antibodies to al integrin, collagen type III and other muscle specific proteins on days 1, 3, 6, 9 and 11 after growth medium was replaced with differentiation medium.