The integrin family of cell surface receptors have important adhesive and signaling functions in a cell. In the vasculature, integrin signaling events play central roles in angiogenesis, cell migration during development and wound healing, inflammatory responses, and hemostasis. To further understand the bidirectional signal transduction by integrins, a novel unbiased genetic strategy for selection of induced mutations that affect alphaIIBbeta3 integrin has been developed. Recent data indicate that some of the mutations were not intrinsic to the integrin, thus suggesting the existence of novel cellular integrin regulatory pathways. The focus of this proposal is to use somatic-cell genetic approaches to identify and characterize novel cellular regulatory proteins which mediate the activation (inside-out signaling) of integrins. Using a CHO cell line expressing platelet-specific integrins alphaIIBbeta3 as a model system, I propose to isolate integrin signaling defective mutants, to perform functional complementation by somatic cell hybridization, and to physically map and then positionally clone the functional cellular factors necessary for integrin activation. A fundamental understanding of intracellular integrin signaling cascade is expected from this work. The knowledge may provide the basis for novel therapeautic strategies.
