αvβ3 and αvβ5 integrins and their role in muscle precursor cell adhesion

Background information . Functional adaptation of skeletal muscle is a requirement for different muscle groups (e.g. craniofacial, ocular and limb) to undergo site‐specific changes. Such tissue remodelling depends on dynamic interactions between muscle cells and their extracellular matrix, via participation of multifunctional molecules such as integrins. In view of data suggesting a role in fundamental muscle biology and muscle development in other systems, the present study has focused on expression and function of αv integrins, in cultured adult human craniofacial muscle (masseter) precursor cells and myotubes, and the predominantly fibroblastic IC (interstitial cells) population. Results and conclusions . Flow‐cytometric phenotyping and immunofluorescence phenotyping show that αv, αvβ3 and αvβ5 are expressed in all mononuclear cells (muscle precursors and IC) seeded on muscle extracellular molecules such as gelatin, VN (vitronectin) and FN (fibronectin). In this system, blockade of αv activity using a function‐perturbing antibody abrogates cell migration on VN and FN. αv integrins act predominantly as VN receptors as cell—substrate attachment is diminished when αv neutralizing agents are introduced into cultures seeded on VN, and this inhibition is reversible; these integrins also appear to be minor FN receptors. These results demonstrate that the αv subset of integrins present on both myogenic precursors and IC is an essential cohort of VN and, to a lesser extent, FN receptors mediating cell adhesion and, either directly or indirectly, arbiters of cell motility.