CCK-stimulated changes in pancreatic acinar morphology are mediated by rho

Background/Aims: Treatment of isolated pancreatic acini with high concentrations of cholecystokinin (CCK) is known to induce rapid changes in the cellular morphology. The signalling pathways remain to be characterized. Methods: Pancreatic acini were permeabilized by digitonin and incubated with various agents. The acinar morphology was investigated by microscopy. The activation of p125 focal adhesion kinase was determined by Western blot analysis. Amylase was measured photometrically. Results: The functionality of the permeabilized acini was tested by measuring stimulated amylase release. 300 muM GTPgammaS was almost as efficient as CCK to stimulate amylase release, while 300 muM GDP S inhibited the CCK-stimulated amylase release. Stimulation of permeabilized acini with 0.1 muM CCK induced similar morphological changes as in unpermeabilized acini. Incubation of permeabilized acini with GTPgammaS mimicked the CCK-induced changes, whereas a preincubation with GDP S prevented the CCK effects on the acinar morphology. Inhibition of the small G protein rho, which activates p125 focal adhesion kinase, by Clostridium botulinum C3 transferase also prevented the CCK-stimulated morphological changes. Preincubation of intact acini with cell-permeable inhibitors of protein kinase C, MEK or p38MAPK, or with the intracellular calcium chelator BAPTA/AM was without significant effect on the CCK-stimulated changes. Conclusion: The CCK-induced morphological changes seem to be mediated by G protein signalling via the small G protein rho and the associated activation of p125 focal adhesion kinase. Copyright (C) 2002 S, Karger AG, Basel.