FAS APO-1(CD95)-INDUCED APOPTOSIS OF PRIMARY HEPATOCYTES IS INHIBITEDBY CAMP/

Fas/APO-1(CD-95) activation induced rapid apoptotic cell death of prim ary rat hepatocytes in suspension culture. Activators of cAMP-dependen t protein kinase (glucagon and N-6-benzoyl-cAMP) protected against apo ptosis, whereas the specific cAMP-kinase inhibitor (Rp)-8-Br-cAMPS enh anced Pas-induced death. The latter observation indicated that even th e basal cAMP level may provide partial protection against Pas-induced hepatocyte apoptosis. Two-dimensional gel electrophoresis revealed dec reased phosphorylation of several proteins in Pas-activated cells. Mos t of these dephosphorylations were attenuated or not observed in cells simultaneously stimulated by anti-Pas and cAMP, indicating a tight co rrelation between the dephosphorylations and death. Elevation of cAMP rescued the cells not only from the Pas-induced morphological changes and dephosphorylation, but also from functional deterioration. Whereas cells treated with anti-Pas alone quickly lost plating efficiency, he patocytes co-treated with glucagon retained their ability to adhere an d spread on a collagen substratum. (C) 1997 Academic Press.