Cell-surface regulation of β1-integrin activity on developing retinal neurons

Abstract

INTEGRINS are a family of αβ heterodimeric receptors that mediate cell-cell and cell-substratum interactions. Integrin binding to extracellular ligands regulates cell adhesion, shape, motility, intracellular signalling and gene expression^1-3. Mechanisms that regulate integrin function are, therefore, central to the participation of integrins in a diverse set of cellular events. Here we report the identification of TASC, a monoclonal antibody to a novel epitope on the integrin β₁ subunit, which inhibits cell adhesion to vitronectin but promotes adhesion to laminin and collagen types I and IV. We show that developing retinal neurons that have lost responsiveness to laminin⁴ regain the ability to bind laminin in the presence of TASC. Thus, β₁-class integrins are likely to occupy multiple affinity states that can be modulated at the cell surface.