Signaling triggered by Thy-1 interaction with ？3 integrin on astrocytes is an essential step towards unraveling neuronal Thy-1 function

thy-1 is an abundant neuronal glycoprotein in mammals. despite such prevalence, thy-1 function remains largely obscure in the absence of a defined ligand. recently described evidence that thy-1 interacts with ？3 integrin on astrocytes will be discussed. thy-1 binding to ？3 integrin triggers tyrosine phosphorylation of focal adhesion proteins in astrocytes, thereby promoting focal adhesion formation, cell attachment and spreading. thy-1 has been reported to modulate neurite outgrowth by triggering a cellular response in neurons. however, our data indicate that thy-1 can also initiate signaling events that promote adhesion of adjacent astrocytes to the underlying surface. preliminary results suggest that morphological changes observed in the actin cytoskeleton of astrocytes as a consequence of thy-1 binding is mediated by small gtpases from the rho family. our findings argue that thy-1 functions in a bimodal fashion, as a receptor on neuronal cells and as a ligand for ？3 integrin receptor on astrocytes. since thy-1 is implicated in the inhibition of neurite outgrowth, signaling events in astrocytes are likely to play an important role in this process