Integrins as receptors for laminins

Laminins are a family of trimeric glycoproteins present in the extracellula r matrix and the major constituents of basement membranes. Integrins are al pha beta transmembrane receptors that play critical roles in both cell-matr ix and cell-cell adhesion. Several members of the integrin family, includin g alpha1 beta1, alpha2 beta1, alpha3 beta1, alpha6 beta1, alpha7 beta1 and alpha6 beta4 heterodimers serve as laminin receptors on a variety of cell t ypes. This review summarizes recent advances in understanding the involveme nt of individual integrins in cell interactions with laminins and the roles of laminin-binding integrins in adhesion-mediated events in vertebrates, i ncluding embryonic development, cell migration and tumor cell invasiveness, cell proliferation and differentiation, as well as basement membrane assem bly. We discuss the regulation of integrin function via alternative splicin g of cytoplasmic domains of alpha and beta subunits of the integrin recepto rs for laminins and present examples of functional collaboration between la minin-binding integrins and non-integrin laminin receptors. Advances in our understanding of the laminin-binding integrins continue to demonstrate the essential roles these receptors play in maintaining cell polarity and tiss ue architecture. Microsc. Res. Tech. 51:280-301, 2000. (C) 2000 Wiley-Liss, Inc.