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pubmed:abstractText |
Acinar cells require a functional apical actin web for secretion. During stimulation with supraphysiological concentrations of cholecystokinin (CCK), a condition that mimics acute pancreatitis, the actin filaments disintegrate. This leads to retention of secretory enzymes and, together with their premature activation, results in cell injury. Actin filaments are anchored through membrane-associated protein complexes that can be regulated through Src-family kinases in some model systems. Here we show that the Src-family kinases Yes and Lyn, but not Src and Fyn, are expressed in isolated pancreatic acini of Wistar rats. Upon stimulation with supramaximal secretory CCK (10(-8) M), Yes became reversibly tyrosine-phosphorylated and activated within 2 min. Immunocytochemical and subcellular fractionation studies showed reversible redistribution of Yes to the apical actin web and to the membrane fraction within 5 min. Coimmunoprecipitation demonstrated that Yes forms a complex with the focal adhesion protein Pyk2, which increased with CCK stimulation. In functional studies, inhibition of Src-kinase activity with PP2 partially reversed actin disintegration and also restored amylase secretion. We conclude that Yes participates in the regulation of the acinar cell actin, probably by interaction with Pyk2.
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