The functional role of integrins in cell adhesion, motility and differentiation

Integrins mediate, in part, the adhesion and motility of cells on extracellular matrix proteins. They also play a role in the processes of cellular differentiation. The contributions of individual integrins in these events have not been fully characterized. A series of Chinese Hamster Ovary (CHO) variants were selected which are deficient in expression of the integrin ;To explore the role of the cytoplasmic domain of the alpha 5 subunit in FnR function, two truncated versions of the human alpha subunit were constructed and transfected into a 2% FnR deficient clone. Results from adhesion and motility assays on Fn suggest that the cytoplasmic domain of the alpha subunit contributes little to the "house keeping" functions of the FnR (such as adhesion and motility), although it may contribute to the normal expression of the FnR. Results from motility assays conducted on Vn suggest that a negative regulatory element for Vn motility may exist within the cytoplasmic domain of the ;The participation of integrin in angiogenesis was the subject of the last study. The process of in vitro angiogenesis also involves integrins since monoclonal antibodies to integrin alpha6 or beta1 subunits can completely block the process. The concentrations of anti-integrin antibodies needed to block in vitro angiogenesis are much lower than those required to block cell adhesion, and are sufficient to occupy less than 10% of the alpha6 or beta1 subunits available at the cell surface. These results suggest that integrins are critically involved during angiogenesis in processes beyond their usual role in cell adhesion. (Abstract shortened by UMI.).