Redistribution of protein kinase C isoforms in rat pancreatic acini duringlactation and weaning

Freshly enzymatically isolated pancreatic acini from lactating and weaning Wistar rats were used to investigate the role of protein kinase C (PKC) iso forms during these physiologically relevant pancreatic secretory and growth processes. The combination of immunoblot and immunohistochemical analysis shows that the PKC isoforms alpha, delta, and epsilon are present in pancre atic acini from control, lactating and weaning rats. A vesicular distributi on of PKC-alpha, -delta, and -epsilon was detected by immunohistochemical a nalysis in the pancreatic acini from all the experimental groups. PKC-F sho wed the strongest PKC immunoreactivity (PKC-IR). In this vesicular distribu tion, PKC-IR was located at the apical region of the acinar cells. No diffe rences mere observed between control, lactating and meaning rats. However, the immunoblot analysis of pancreatic PKC isoforms during lactation and mea ning showed a significant translocation of PKC-delta from the cytosol to th e membrane fraction when compared with control animals. Translocation of PK C isoforms (alpha, delta and epsilon) in response to 12-O-tetradecanoyl pho rbol 13-acetate (TPA) 1 mu M (15 min, 37 degrees C) was comparable in pancr eatic acini from control, lactating and weaning rats. In the control group, a significant translocation of all the isoforms (alpha, delta and epsilon) from the cytosol to the membrane was observed. The PKC isoform most transl ocated by TPA was PKC-delta. In contrast, no statistically significant incr ease in PKC-delta translocation was detected in pancreatic acini isolated f rom lactating or meaning rats. These results suggest that the PKC isoforms are already translocated to the surface of the acinar cells from lactating or meaning rats. In addition, they suggest that isoform specific spatial PK C distribution and translocation occur in association with the growth respo nse previously described in the rat exocrine pancreas during lactation and weaning. (C) 1999 Federation of European Biochemical Societies.