Integrin repertoire on myogenic cells changes during the course of primary myogenesis in the mouse

Cells interact with the extracellular matrix through receptors, most commonly of the integrin family. We (Cachaco et al. [20031 Development 130:1659-1671) and others (Schwander et al. [20031 Dev. Cell 4:673-685) have demonstrated a role for beta 1 integrins in mouse primary myogenesis. However, it is unclear what a subunits pair with beta 1 during this process in vivo. Here, we determined a subunit expression patterns at embryonic day (E) 11.5-E14.5. Differentiated myotomal myocytes express all a. subunits studied. As the muscle masses form both in trunk (E12.5) and limbs (E11.5-E12.5), laminin receptors alpha 6 beta 1 and alpha 7 beta 1 are undetectable, and an assembled laminin matrix is absent. Instead alpha 1 beta 1, alpha 4 beta 1, alpha 5 beta 1 and an alpha v-containing integrin are expressed and unassembled laminin and fibronectin are abundant around myogenic cells. At E13.5-E14.5, alpha 6 beta 1 and alpha 7 beta 1 are expressed, and a laminin matrix forms around individual myotubes. Thus, myogenic cells change their integrin expression pattern during the course of primary myogenesis in the mouse, suggesting different roles for fibronectin- and laminin-containing matrices in this process. (c) 2005 Wiley-Liss, Inc.