The glucagon-like peptide-2 receptor mediates direct inhibition of cellular apoptosis via a cAMP-dependent protein kinase-independent pathway

Glucagon and the glucagon-like peptides regulate metabolic functions via si gnaling through a glucagon receptor subfamily of G protein-coupled receptor s, Activation of glucagon-like peptide-2 receptor (GLP-2R) signaling mainta ins the integrity of the intestinal epithelial mucose via regulation of cry pt cell proliferation. Because GLP-2 decreases mortality and reduces intest inal apoptosis in rodents after experimental injury, we examined whether GL P-2R signaling directly modifies the cellular response to external injury. We show here that activation of GLP-2R signaling inhibits cycloheximide-ind uced apoptosis in baby hamster kidney fibroblasts expressing a transfected GLP-2 receptor. GLP-2 reduced DNA fragmentation and improved cell survival, in association with reduced activation of caspase-3 and decreased poly(ADP -ribose) polymerase cleavage and reduced caspase-8 and caspase-9-like activ ities. Both GLP-2 and forskolin reduced mitochondrial cytochrome c release and decreased the cycloheximide-induced cleavage of caspase-3 in the presen ce or absence of the PKA inhibitor H-89, Similarly, GLP-2 increased cell su rvival following cycloheximide in the presence of the kinase inhibitors PD9 8054 and LY294002. These findings provide evidence that signaling through G ; protein-coupled receptors of the glucagon superfamily is directly linked to regulation of apoptosis and suggest the existence of a cAMP-dependent pr otein kinase-, phosphatidylinositol 3-kinase-, and mitogen-activated protei n kinase-independent pathway coupling GLP-2R signaling to caspase inhibitio n and cell survival.