oxyntomodulin and benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone

Glucagon and the glucagon-like peptides regulate metabolic functions via signaling through a glucagon receptor subfamily of G protein-coupled receptors. Activation of glucagon-like peptide-2 receptor (GLP-2R) signaling maintains the integrity of the intestinal epithelial mucosa via regulation of crypt cell proliferation. Because GLP-2 decreases mortality and reduces intestinal apoptosis in rodents after experimental injury, we examined whether GLP-2R signaling directly modifies the cellular response to external injury. We show here that activation of GLP-2R signaling inhibits cycloheximide-induced 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 activities. Both GLP-2 and forskolin reduced mitochondrial cytochrome c release and decreased the cycloheximide-induced cleavage of caspase-3 in the presence or absence of the PKA inhibitor H-89. Similarly, GLP-2 increased cell survival following cycloheximide in the presence of the kinase inhibitors PD98054 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 protein kinase-, phosphatidylinositol 3-kinase-, and mitogen-activated protein kinase-independent pathway coupling GLP-2R signaling to caspase inhibition and cell survival.

Topics: Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Caspase 3; Caspase 8; Caspase 9; Caspases; Cell Division; Cell Line; Cell Survival; Chromones; Colforsin; Cricetinae; Cyclic AMP-Dependent Protein Kinases; Cycloheximide; Cysteine Proteinase Inhibitors; Cytochrome c Group; Cytosol; DNA Fragmentation; Electrophoresis, Agar Gel; Enzyme Activation; Enzyme Inhibitors; Epithelium; Fibroblasts; Flavonoids; Glucagon-Like Peptide 2; Glucagon-Like Peptide-1 Receptor; Glucagon-Like Peptides; Intestinal Mucosa; Isoquinolines; Microscopy, Fluorescence; Mitochondria; Morpholines; Peptides; Poly(ADP-ribose) Polymerases; Protein Synthesis Inhibitors; Receptors, Cell Surface; Receptors, Glucagon; Signal Transduction; Sulfonamides; Time Factors; Transfection