Subcellular distribution of phospholipase C isoforms in rodent pancreas and gastric mucosa

Phosphoinositide-specific phospholipase C (PLC) has been implicated as a pa rticipant in cell proliferation as well as enzyme and hormone secretion. De fining the subcellular distribution of PLC isoforms would possibly contribu te to further understanding of their function. We investigated the intracel lular distribution of four PLCs (beta 1, beta 2, beta 3, and gamma 1) in mo use pancreatic cells as well as mouse and rat gastric mucosa cells by ultra structural immunocytochemistry. In pancreatic acinar cells, PLC beta 1 and PLC gamma 1 were demonstrated in the zymogen granules while PLC beta 2 was present in the granulae as well as the endoplasmic reticulum (ER), and PLC beta 3 was prominent in the ER. In the endocrine pancreas, PLC beta 2 immun olabeling was expressed in the secretory granulae of alpha, beta, delta, an d pancreatic polypeptide cells. PLC beta S3 showed a slight labeling in the nucleus and ER of all four pancreatic endocrine cell types while PLC gamma 1 was prominent in alpha cell granulae. In the gastric mucosa cells, PLC b eta 2 was highly expressed in the heterochromatin areas and in the ER of pa rietal, chief, mucous, and enterochromaffin-like cells. PLC beta 3 were exp ressed in a manner similar to PLC beta 2 in those cells; however, no immuno reaction was seen in the ER of parietal cell. PLC gamma 1 was demonstrated in the chief cell granulae. One possible, although yet speculative, interpr etation of our results is that the studied PLC isoforms may be involved in processing in pancreatic secretory granulae and that nuclear PLC beta 2 and PLC beta 3 signaling pathways may be operative in the cells of the gastric mucosa.