PATTERNS & PHENOTYPES Integrins in the Mouse Myotome: Developmental Changes and Differences Between the Epaxial

Integrins are cellular adhesion receptors that mediate signaling and play key roles in the development of multicellular organisms. However, their role in the cellular events leading to myotome formation is completely unknown. Here, we describe the expression patterns of the 1, 4, 5, 6, and 7 integrin subunits in the mouse myotome and correlate them with the expression of several differentiation markers. Our results indicate that these integrin subunits may be differentially involved in the various phases of myogenic determination and differentiation. A detailed characterization of the myogenic cell types expressing the 4 and 6 subunits showed a regionalization of the myotome and dermomyotome based on cell-adhesion properties. We conclude that 61 may be an early marker of epaxial myogenic progenitor cells. In contrast, 41 is up-regulated in the intercalated myotome after myocyte differentiation. Furthermore, 41 is expressed in the hypaxial dermomyotome and is maintained by early hypaxial myogenic progenitor cells colonizing the myotome. Developmental Dynamics 231:402–415, 2004