BETA-1 INTEGRIN LIGATION STIMULATES TYROSINE PHOSPHORYLATION OF PHOSPHOLIPASE C-GAMMA-1 AND ELEVATES INTRACELLULAR CA2-CELLS( IN PANCREATICACINAR)

We have recently reported increased tyrosine (TYR) phosphorylation of a number of pancreatic acinar cell proteins following antibody ligatio n of beta 1 integrins (Wrenn and Herman, Biochem. Biophys. Res. Commun . 208, 1995, 978-984). Concurrent with this TYR phosphorylation was a marked activation of protein kinase C (PKC). This led us to investigat e phospholipase C gamma 1 (PLC gamma 1),a key enzyme responsible for d iacylglycerol generation, as a target for integrin-mediated TYR phosph orylation. Staining with antiphosphotyrosine antibodies revealed incre ased TYR phosphorylation of immunoprecipitated PLC gamma 1 prepared fr om beta 1 integrin-ligated acinar cells. Subsequent stripping and repr obing of Western blots with polyclonal anti-PLC gamma 1 was confirmato ry. Over this same time period, intracellular [Ca2+] increased from <1 00 nM to 600 nM, further suggesting a functional relevance of integrin -linked phosphorylation as a regulatory mechanism in exocrine pancreas . (C) 1996 Academic Press, Inc.