Glucagon-like peptide-2 receptor activation in the rat intestinal mucosa.
Glucagon-like peptide-2 (GLP-2) increases small intestinal growth and function in rodents and human subjects. GLP-2 exerts its effects through a seven-transmembrane domain, G protein-coupled receptor (GLP-2R), stimulating cAMP generation and activating protein kinase A signaling in heterologous cell lines transfected with the GLP-2R. As intestinal cell lines expressing the GLP-2R have not been identified, we developed methods for studying GLP-2R signaling in the rat small intestinal mucosa in vitro. Isolated rat intestinal mucosal cells expressed mRNA transcripts for the GLP-2R, as well as for chromogranin A and beta-tubulin III, markers for enteroendocrine and neural cells, respectively. cAMP production in response to [Gly2]GLP-2, a degradation-resistant analog of GLP-2, was maximal at 10-11 m (268 +/- 93% of control, P < 0.001), with reduced cAMP accumulation observed at higher doses. The cAMP response was diminished by pretreatment with 10-9 m GLP-2, and was abolished by pretreatment with 10-6 m GLP-2 (P < 0.05), indicating receptor desensitization. GLP-2 treatment of isolated mucosal cells increased 3H-thymidine incorporation (to 128 +/- 8% of controls, P < 0.05), and this was prevented by inhibition of the protein kinase A pathway with H89. In contrast, GLP-2 did not affect p44/p42 MAPK phosphorylation or the levels of cytosolic calcium in the mucosal cell preparation. These results provide the first evidence that activation of the endogenous rat mucosal GLP-2 receptor is linked to activation of a cAMP/protein kinase A-dependent, growth-promoting pathway in vitro.
Walsh
Natalie A
NA
Department of Physiology, University of Toronto, Toronto, Canada M5S 1A8.
Yusta
Bernardo
B
DaCambra
Mark P
MP
Anini
Younes
Y
Drucker
Daniel J
DJ
Brubaker
Patricia L
PL
D000818:Animals; D002118:Calcium / Q000378:metabolism; D053379:Chromogranin A; D002864:Chromogranins / Q000235:genetics; D000242:Cyclic AMP / Q000096:biosynthesis; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D053767:Glucagon-Like Peptide 2; D000067757:Glucagon-Like Peptide-1 Receptor; D004763:Glucagon-Like Peptides; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009994:Osmolar Concentration; D010455:Peptides / Q000008:administration & dosage; D010766:Phosphorylation / Q000187:drug effects; D020033:Protein Isoforms / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D018027:Receptors, Glucagon / Q000235:genetics / Q000378:metabolism*; D013936:Thymidine / Q000378:metabolism; D014404:Tubulin / Q000235:genetics
D053379:Chromogranin A; D002864:Chromogranins; C000593833:GLP1R protein, human; C000593835:Glp1r protein, rat; D053767:Glucagon-Like Peptide 2; D000067757:Glucagon-Like Peptide-1 Receptor; D010455:Peptides; D020033:Protein Isoforms; D012333:RNA, Messenger; D018027:Receptors, Glucagon; D014404:Tubulin; D004763:Glucagon-Like Peptides; D000242:Cyclic AMP; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium; D013936:Thymidine