Differential expression of CD95, Bcl-2, and Bax in rat gastric chief and parietal cells

Apoptotic cell death is common in the inflamed gastric mucosa, but its role in the regulation of cell homeostasis in normal gastric mucosa is unknown. We investigated the expression of CD95, Bcl-2, and Pax and their roles in the regulation of apoptosis in normal rat gastric mucosa and in cultures of highly enriched rat chief and parietal cells by immunostaining, Western bl otting, and FAGS. In intact tissue CD95, Bcl-2, and Bar were localized pred ominantly in the glandular base region in chief cells. In freshly isolated cells, expression of CD95, Bcl-2, and Bar was much more pronounced in chief cells than in parietal cells. A lower intracellular Bcl-2/Bax ratio sugges ting a higher susceptibility to apoptosis was noticed in chief rather than in parietal cells. In extended cultures of parietal and chief cells, Pax ex pression was upregulated and Bcl-2 expression was downregulated. These regu latory changes, presumably caused by in vitro effects, were not associated with an increase in spontaneous apoptosis. Treatment of chief and parietal cells with Fas-ligand induced apoptosis of all CD95 expressing cells. Expre ssion of CD95, Bcl-2, and Pax predominantly in chief cells suggests that in this cell type regulation of apoptosis may differ from that in parietal ce lls. Binding of Fast with functionally active CD95 receptors on chief and p arietal cells may be relevant for induction of apoptosis in inflamed gastri c mucosa. (C) 2001 Wiley-Liss, Inc.