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 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 crelease 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. 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 crelease 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. glucagon-like peptide GLP-2 receptor 5-bromo-4-chloro-3-indolyl β-d-galactopyranoside baby hamster kidney phosphate-buffered saline poly(ADP-ribose) polymerase 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonic acid cAMP-dependent protein kinase phosphatidylinositol G protein-coupled receptor extracellular signal-regulated kinase nerve growth factor cycloheximide p-nitroanilide Glucagon and the glucagon-like peptides are co-encoded within a common precursor, proglucagon, that is expressed in a tissue-specific manner, giving rise to glucagon in the pancreatic A cells and glucagon-like peptides-1 and 2 in the endocrine cells of the gastrointestinal tract (1Mojsov S. Heinrich G. Wilson I.B. Ravazzola M. Orci L. Habener J.F. J. Biol. Chem. 1986; 261: 11880-11889Abstract Full Text PDF PubMed Google Scholar, 2Drucker D.J. Diabetes. 1998; 47: 159-169Crossref PubMed Google Scholar). Proglucagon-derived peptides play important roles in regulation of metabolic function following nutrient assimilation (2Drucker D.J. Diabetes. 1998; 47: 159-169Crossref PubMed Google Scholar). Glucagon regulates hepatic glucose production and maintains plasma glucose in a narrowly defined physiological range by opposing the actions of insulin at the hepatocyte. Glucagon-like peptide-1 (GLP-1)1 is secreted from the gut following nutrient ingestion and controls glycemia via stimulatory and inhibitory effects on insulin and glucagon, respectively (2Drucker D.J. Diabetes. 1998; 47: 159-169Crossref PubMed Google Scholar, 3Kieffer T.J. Habener J.F. Endocr. Rev. 1999; 20: 876-913Crossref PubMed Google Scholar). In contrast, glucagon-like peptide-2 (GLP-2) exerts its principal actions on nutrient homeostasis proximal to nutrient absorption via regulation of the integrity of the mucosal epithelium (4Drucker D.J. Ehrlich P. Asa S.L. Brubaker P.L. Proc. Natl. Acad. Sci. U. S. A. 1996; 93: 7911-7916Crossref PubMed Scopus (708) Google Scholar, 5Drucker D.J. Trends Endocrinol. Metab. 1999; 10: 153-156Abstract Full Text Full Text PDF PubMed Scopus (50) Google Scholar). In addition to metabolic effects regulating fuel homeostasis, glucagon-like peptides also exert specific actions on cell proliferation and tissue regeneration. Glucagon potentiates proliferation of rat hepatocytes (6Kimura M. Ogihara M. Eur. J. Pharmaco. 1997; 324: 267-276Crossref PubMed Scopus (42) Google Scholar) and stimulates hepatic DNA synthesis following partial hepatectomy in vivo (7Bucher N.L. Swaffield M.N. Adv. Enzyme Regul. 1975; 13: 281-293PubMed Google Scholar). GLP-1 increases islet proliferation in mice (8Edvell A. Lindstrom P. Endocrinology. 1999; 140: 778-783Crossref PubMed Scopus (132) Google Scholar) and enhances islet regeneration and lowers blood glucose in rats following partial pancreatectomy (9Xu G. Stoffers D.A. Habener J.F. Bonner-Weir S. Diabetes. 1999; 48: 2270-2276Crossref PubMed Scopus (1087) Google Scholar). GLP-1 also appears to stimulate islet neogenesis via induction of pdx-1 expression in normal and diabetic rodents (10Stoffers D.A. Kieffer T.J. Hussain M.A. Drucker D.J. Egan J.M. Bonner-Weir S. Habener J.F. Diabetes. 2000; 49: 741-748Crossref PubMed Scopus (515) Google Scholar). GLP-2 stimulates intestinal crypt cell proliferation in normal rats and mice leading to villus hyperplasia and expansion of the mucosal epithelium (4Drucker D.J. Ehrlich P. Asa S.L. Brubaker P.L. Proc. Natl. Acad. Sci. U. S. A. 1996; 93: 7911-7916Crossref PubMed Scopus (708) Google Scholar, 11Drucker D.J. Shi Q. Crivici A. Sumner-Smith M. Tavares W. Hill M. Deforest L. Cooper S. Brubaker P.L. Nature Bio/Technology. 1997; 15: 673-677Crossref PubMed Scopus (223) Google Scholar, 12Tsai C.-H. Hill M. Asa S.L. Brubaker P.L. Drucker D.J. Am. J. Physiol. 1997; 273: E77-E84Crossref PubMed Google Scholar). The beneficial effects of GLP-2 in experimental models of intestinal injury have largely been attributed to enhancement of mucosal regeneration via GLP-2-dependent stimulation of crypt proliferation (13Drucker D.J. Yusta B. Boushey R.P. Deforest L. Brubaker P.L. Am. J. Physiol. 1999; 276: G79-G91PubMed Google Scholar, 14Boushey R.P. Yusta B. Drucker D.J. Am. J. Physiol. 1999; 277: E937-E947Crossref PubMed Google Scholar, 15Scott R.B. Kirk D. MacNaughton W.K. Meddings J.B. Am. J. Physiol. 1998; 275: G911-G921Crossref PubMed Google Scholar, 16Prasad R. Alavi K. Schwartz M.Z. J. Pediatr. Surg. 2000; 35: 357-359Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). Although GLP-2 inhibits apoptosis in the crypt compartment following administration of the nonsteroidal anti-inflammatory agent indomethacin (14Boushey R.P. Yusta B. Drucker D.J. Am. J. Physiol. 1999; 277: E937-E947Crossref PubMed Google Scholar), the mechanisms coupling GLP-2 signaling to anti-apoptotic effects in a direct or indirect manner remain unknown. Because intestinal cell lines expressing the endogenous GLP-2 receptor have not yet been identified, we have now examined the effects of GLP-2 receptor signaling on cell death in heterologous cells expressing the transfected rat GLP-2 receptor. Tissue culture medium, serum, and other supplements, including G418, were from Life Technologies, Inc. Cycloheximide, forskolin, protease inhibitor mixture (P-2714), and 4′,6-diamidino-2-phenylindole were purchased from Sigma. Recombinant human [Gly2]-GLP-2 was a kind gift from NPS Allelix Inc. (Mississauga, Canada). The caspase inhibitors Z-VAD-fmk and Z-YVAD-fmk and the kinase inhibitors H89 and LY294002 were obtained from Calbiochem (San Diego, CA). Ac-IETD-pNA and Ac-LEHD-pNA were fromBIOSOURCE International (Camarillo, CA). PD98059 was obtained from New England Biolabs (Beverly, MA). X-gal was purchased from BioShop Canada Inc. (Burlington, Canada). All electrophoresis and immunoblotting reagents were purchased from Bio-Rad. The pCRE/β-galactosidase reporter plasmid (17Chen W. Shields T.S. Stork P.J. Cone R.D. Anal. Biochem. 1995; 226: 349-354Crossref PubMed Scopus (181) Google Scholar) and the expression vector MtR(AB) (18Correll L.A. Woodford T.A. Corbin J.D. Mellon P.L. McKnight G.S. J. Biol. Chem. 1989; 264: 16672-16678Abstract Full Text PDF PubMed Google Scholar) were gifts from R. D. Cone (Portland, OR) and G. S. McKnight (Seattle, WA), respectively. Baby hamster kidney (BHK) fibroblasts containing the stably integrated pcDNA3.1 plasmid (BHK-pcDNA3) (Invitrogen, Carlsbad, CA) or the identical plasmid directing expression of the rat GLP-2 receptor (BHK-GLP-2R) were propagated as described previously (19Yusta B. Somwar R. Wang F. Munroe D. Grinstein S. Klip A. Drucker D.J. J. Biol. Chem. 1999; 274: 30459-30467Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar). Stock cultures were trypsinized, and the cells were replated in culture medium lacking G418. Upon reaching 80–90% confluency, the cultures were starved in Dulbecco's modified Eagle's medium supplemented with 0.2% calf serum for 15–17 h prior to apoptosis induction by cycloheximide in the same medium, in the presence or absence of the indicated peptides or drugs for the indicated period of time. Adherent cells were then scraped off the culture dishes in PBS, combined with detached cells floating in the medium and spun at 12,000 rpm for 30 s. Depending on the type of assay to be performed, cell pellets were either stored at −70 °C or used immediately. Cycloheximide was dissolved in anhydrous ethyl alcohol, h[Gly2]-GLP-2 in PBS, pH 7.4, and forskolin, H89, LY294002, PD98059, Z-VAD-fmk, and Z-YVAD-fmk in dimethyl sulfoxide. Drug stock solutions were stored at −70 °C and diluted as required in their corresponding solvents, immediately before being added either alone or in to the cultures at the cultures were to the same as cells in the absence of the and dimethyl were identical in culture of the of cell death was by of the cultures for the presence of cell and the of plasma as as were on a of of the cultures were with a and the and cultures were with and then with 4′,6-diamidino-2-phenylindole in The cells were with before with and a were a and the of DNA fragmentation with DNA was from cells and with and to DNA were by electrophoresis in in and by after was on of the a and the were to either alone or cycloheximide in the presence or absence of the indicated drugs and the indicated of following apoptosis the of cells in was by the of a at the assay pellets obtained as indicated were at °C in containing and protease inhibitor mixture were at 12,000 rpm for at for at °C with containing and stored at −70 °C was a assay and serum as a of cell were by electrophoresis and The was with in containing 0.2% and with a at were with a to and to caspase-3 gift of poly(ADP-ribose) polymerase Canada cytochrome New England and were used in The was to and was by the cleavage of reporter with the of and were at °C in pH 7.4, containing and and spun at 12,000 rpm for at and the was were at °C and of cell and of reporter in pH 7.4, containing 2 and of the p-nitroanilide was at were for and to of cells was by as described previously (19Yusta B. Somwar R. Wang F. Munroe D. Grinstein S. Klip A. Drucker D.J. J. Biol. Chem. 1999; 274: 30459-30467Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar). cultures were transfected with of a expression as a for of CA) DNA or with the plasmid of MtR(AB) expression vector and DNA for a of cells were in medium for 15–17 h modified Eagle's medium with 0.2% calf to apoptosis by cycloheximide in the presence or absence of the indicated and then in cells were by with X-gal in containing and The of cells in the that evidence of apoptosis was by cells from at cells were as with a as to the of cells The of PKA inhibition by the transfected MtR(AB) expression plasmid was by its to h[Gly2]-GLP-2 and activation of a reporter as described previously (19Yusta B. Somwar R. Wang F. Munroe D. Grinstein S. Klip A. Drucker D.J. J. Biol. Chem. 1999; 274: 30459-30467Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar). The inhibitory of H89 on and h[Gly2]-GLP-2 or cAMP-dependent protein kinase was in a cAMP-dependent protein kinase of the the of the the to be from the on at pH PKA was defined as that be by protein kinase peptide were in mitochondrial pH 7.4, and protease inhibitor mixture and at °C with a and cells at for the was for at to the for The obtained containing the was for at to the and then stored at −70 The was in mitochondrial and then in the same and stored at −70 °C in and mitochondrial was before the for as described of were of and were the The glucagon-like peptide-2 receptor is expressed in a tissue-specific in the and P. G. Wang L. K. Sumner-Smith M. Drucker D.J. Crivici A. Proc. Natl. Acad. Sci. U. S. A. 1999; PubMed Scopus Google Scholar). by and intestinal cell lines that the endogenous GLP-2 receptor have not yet been we have GLP-2R signaling and its coupling to anti-apoptotic in fibroblasts stably transfected with the rat GLP-2 receptor (19Yusta B. Somwar R. Wang F. Munroe D. Grinstein S. Klip A. Drucker D.J. J. Biol. Chem. 1999; 274: 30459-30467Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar). of type cells or cells with cycloheximide alone at that protein synthesis by a in cell In contrast, of cells with cycloheximide and h[Gly2]-GLP-2 or forskolin in improved cell survival A and a forskolin that not stimulate on the cycloheximide-induced in cell not cell death was reduced by the inhibitor Z-VAD-fmk not by inhibitor of The of cycloheximide-induced cell death was in the presence of a inhibitor of apoptosis G.S. P. J. Biol. Chem. 1997; Full Text Full Text PDF PubMed Scopus Google Scholar). cells with apoptosis including and as as fragmentation following with cycloheximide DNA fragmentation was by cycloheximide and reduced by of cells with h[Gly2]-GLP-2 findings are with the activation of apoptosis in cells in and forskolin cells from cycloheximide-induced the of cultures and of cultures for h to alone or in with h[Gly2]-GLP-2 or for of cell cells were as described and with in the presence or absence of h[Gly2]-GLP-2 or at was a assay and expressed as of the obtained from of are the from to in either h[Gly2]-GLP-2 or forskolin of caspase inhibitors on cell cells were with the indicated caspase inhibitors for prior to or alone for was then as described for B. are the in and following apoptosis induction by were to or alone for were after 4′,6-diamidino-2-phenylindole electrophoresis of DNA from cells to for h in the absence or presence of The of the the as indicated by the is in the to provide on the of fragmentation in are of with the of caspase activation for cycloheximide-induced cellular injury, the of the of caspase-3 were increased in a manner following with cycloheximide and reduced following of cells with either h[Gly2]-GLP-2 or forskolin Similarly, the cycloheximide-induced cleavage of was following with either h[Gly2]-GLP-2 or forskolin In contrast, the effects of h[Gly2]-GLP-2 not forskolin on caspase-3 and cleavage were in cells 2 with the of the GLP-2R for of the to apoptosis Because caspase-3 and cleavage are that activation of signaling we the effects of GLP-2 on the activation of proximal caspase following cycloheximide of of caspase that are by caspase-8 or caspase-9-like that h[Gly2]-GLP-2 and forskolin the induction of and following cycloheximide of cells In contrast, forskolin, not h[Gly2]-GLP-2 activation of and caspase-9-like in cells with the of the GLP-2R for of the anti-apoptotic effects of h[Gly2]-GLP-2 in The of caspase induction was by findings that as as a was not following of cells with of cycloheximide not The that GLP-2R signaling was to inhibition of cycloheximide-induced caspase-9-like to mitochondrial cytochrome a of activation 1998; PubMed Scopus Google Scholar). Cycloheximide of cells was with a induction in the of cytochrome Both h[Gly2]-GLP-2 and forskolin the cycloheximide induction of cytochrome from cells Because GLP-2 and forskolin are to exert their effects via activation of and signaling (19Yusta B. Somwar R. Wang F. Munroe D. Grinstein S. Klip A. Drucker D.J. J. Biol. Chem. 1999; 274: 30459-30467Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar, P. G. Wang L. K. Sumner-Smith M. Drucker D.J. Crivici A. Proc. Natl. Acad. Sci. U. S. A. 1999; PubMed Scopus Google Scholar), we the of PKA signaling for cellular apoptosis in the presence or absence of a inhibitor of protein kinase A. alone reduced cell in with the of PKA signaling for cell survival in h[Gly2]-GLP-2 and forskolin increased cell survival after cycloheximide in the presence of that stimulation of signaling is not required for the anti-apoptotic actions of that PKA in we and PKA following of cells with h[Gly2]-GLP-2 or PKA was following of cells with h[Gly2]-GLP-2 or forskolin, and PKA activation by was by in the same These suggest that h[Gly2]-GLP-2 inhibits cycloheximide-induced apoptosis in cells in a with h[Gly2]-GLP-2 and forskolin the cycloheximide-induced cleavage of to the caspase-3 in cells provide evidence for the actions of GLP-2 on PKA was by of a plasmid the of protein kinase A (18Correll L.A. Woodford T.A. Corbin J.D. Mellon P.L. McKnight G.S. J. Biol. Chem. 1989; 264: 16672-16678Abstract Full Text PDF PubMed Google Scholar). of transfected cells following cycloheximide that h[Gly2]-GLP-2 and forskolin a in the of cells of MtR(AB) In contrast, the of a reporter was by h[Gly2]-GLP-2 or forskolin, and the stimulatory was reduced in cells Because activation of the glucagon and GLP-1 receptors been with induction of mitogen-activated protein kinase B. G. P. Biol. 1997; PubMed Scopus Google Scholar, P. S. M.A. W. M. Endocrinology. 1999; 140: PubMed Google Scholar), we the effects of PD98059, a inhibitor of on cycloheximide-induced of cells with PD98059 alone on the of cells in the presence or absence of that is not required for cell survival in cells h[Gly2]-GLP-2 and forskolin increased cell following cycloheximide in the presence of In contrast, the activation of by acid or calf serum was in the presence of PD98059 These findings that the effects of GLP-2R signaling on cell survival following cycloheximide are of activation in Because GLP-1 phosphatidylinositol in cells J. R. S. M. 1999; PubMed Scopus Google Scholar) and is to exert anti-apoptotic effects via induction of R. Cooper 1995; PubMed Scopus Google Scholar), we examined whether the anti-apoptotic effects of GLP-2 be via a of cells with LY294002, inhibitor of phosphatidylinositol reduced cell survival, and of cells with LY294002 and cycloheximide a in survival that with either agent alone In contrast, cell survival was increased in cells with either h[Gly2]-GLP-2 or forskolin in the presence of LY294002 at that activation by either acid or calf serum These that is required for cell survival, the effects of h[Gly2]-GLP-2 on cycloheximide-induced cell death are through a phosphatidylinositol Although signaling through G protein-coupled receptors of the receptor superfamily not previously been to directly provide evidence activation and cell Activation of the receptor apoptosis in heterologous cell M. K. D. 1999; Google Scholar, K. Endocrinol. 1999; 13: PubMed Scopus Google Scholar) and signaling through the receptor in cells of the and S. S. Endocrinol. 2000; PubMed Scopus Google Scholar). Activation of the peptide receptor apoptosis in and the effects of peptide signaling on apoptosis were following of cells with a inhibitor of protein kinase A F. D. B. DNA Biol. 1997; PubMed Scopus Google Scholar), with the of the PKA pathway for in cell In contrast, show that the effects of GLP-2 are Similarly, stimulation of apoptosis following activation of receptor signaling is by a pathway J. D. J. Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar). These findings the of signaling of activation and that effects on are and of cell death been in the and stimulation of with as to induction of apoptosis that is by inhibitors of protein kinase A K. M. S. 1999; PubMed Scopus Google Scholar). Similarly, stimulation of receptor signaling with as also to and effects were by with the protein kinase A inhibitor K. 1998; PubMed Scopus Google Scholar). Although stimulation to activation of in rat inhibition of the pathway on apoptosis K. J. Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar), in with findings that activation was not for GLP-2 inhibition of apoptosis in Although receptors for glucagon, and GLP-2 their effects via activation of and protein kinase A P. G. Wang L. K. Sumner-Smith M. Drucker D.J. Crivici A. Proc. Natl. Acad. Sci. U. S. A. 1999; PubMed Scopus Google Scholar, S. S. P.J. D. W. PubMed Scopus Google Scholar, D.J. J. S. Habener J.F. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar), of glucagon and GLP-1 have evidence for signaling following activation of their receptors (4Drucker D.J. Ehrlich P. Asa S.L. Brubaker P.L. Proc. Natl. Acad. Sci. U. S. A. 1996; 93: 7911-7916Crossref PubMed Scopus (708) Google Scholar, 12Tsai C.-H. Hill M. Asa S.L. Brubaker P.L. Drucker D.J. Am. J. Physiol. 1997; 273: E77-E84Crossref PubMed Google Scholar, B. G. P. Biol. 1997; PubMed Scopus Google Scholar, J. R. S. M. 1999; PubMed Scopus Google Scholar, M. Biochem. J. 1998; PubMed Scopus Google Scholar). Similarly, that GLP-2 a pathway in transfected fibroblasts expressing the human or rat GLP-2 receptor (19Yusta B. Somwar R. Wang F. Munroe D. Grinstein S. Klip A. Drucker D.J. J. Biol. Chem. 1999; 274: 30459-30467Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar, P. G. Wang L. K. Sumner-Smith M. Drucker D.J. Crivici A. Proc. Natl. Acad. Sci. U. S. A. 1999; PubMed Scopus Google Scholar), the effects of GLP-2R signaling on cell survival and caspase activation are via The that also leading to of growth factor receptor M. R. A. 1999; PubMed Scopus Google Scholar) the of signaling of In of GLP-2 in cells in the absence of cycloheximide-induced cellular injury, we not GLP-2-dependent activation of and GLP-2 stimulation to kinase or kinase (19Yusta B. Somwar R. Wang F. Munroe D. Grinstein S. Klip A. Drucker D.J. J. Biol. Chem. 1999; 274: 30459-30467Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar). The findings on the of induction in cells from of in activation of apoptosis by M. J. 1995; PubMed Scopus Google Scholar). Similarly, the pathway is required for the effects of in cells inhibitors as LY294002 also the effects of on cell survival R. Cooper 1995; PubMed Scopus Google Scholar). In contrast, activation of GLP-2R signaling reduced cell death and decreased caspase activation in the presence of or LY294002, or of PKA regulate apoptosis in cell J. S. J. Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Scopus Google Scholar), the evidence from to the existence of a pathway to inhibition of caspase-3 cleavage and of cell Similarly, the of of the inhibitors LY294002 and PD98059 on enhancement of cell survival suggest that the anti-apoptotic effects of GLP-2R are via a and mitogen-activated protein kinase-independent The cellular by cycloheximide for induction of cell death cell remain and mitochondrial and death Although activation of leading to caspase-8 cleavage and caspase-3 activation of the mitochondrial evidence that caspase-8 activation also to mitochondrial cytochrome via a pathway in specific cell J. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar). Although was not expressed in cells prior to or following induction of a death protein cycloheximide-induced the of the death protein in cycloheximide-induced cell death D. J.M. J. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar). The that GLP-2 inhibits the cycloheximide induction of cytochrome crelease and and is with of cycloheximide J. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar) and that GLP-2R signaling with signaling of caspase-3 GLP-2 experimental intestinal injury in rats following intestinal and R.B. Kirk D. MacNaughton W.K. Meddings J.B. Am. J. Physiol. 1998; 275: G911-G921Crossref PubMed Google Scholar, 16Prasad R. Alavi K. Schwartz M.Z. J. Pediatr. Surg. 2000; 35: 357-359Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar, A. Am. J. Physiol. 1997; 273: Google Scholar) and in mice following injury to the and (13Drucker D.J. Yusta B. Boushey R.P. Deforest L. Brubaker P.L. Am. J. Physiol. 1999; 276: G79-G91PubMed Google Scholar, 14Boushey R.P. Yusta B. Drucker D.J. Am. J. Physiol. 1999; 277: E937-E947Crossref PubMed Google Scholar). Although the beneficial effects of GLP-2 on intestinal mucosa were attributed to stimulation of crypt cell proliferation (4Drucker D.J. Ehrlich P. Asa S.L. Brubaker P.L. Proc. Natl. Acad. Sci. U. S. A. 1996; 93: 7911-7916Crossref PubMed Scopus (708) Google Scholar, 12Tsai C.-H. Hill M. Asa S.L. Brubaker P.L. Drucker D.J. Am. J. Physiol. 1997; 273: E77-E84Crossref PubMed Google Scholar, B. G. P. Biol. 1997; PubMed Scopus Google Scholar), we reduced apoptosis in the crypt compartment following GLP-2 of mice with intestinal injury (14Boushey R.P. Yusta B. Drucker D.J. Am. J. Physiol. 1999; 277: E937-E947Crossref PubMed Google Scholar). Because the cellular of intestinal GLP-2 receptor expression not yet been identified, in a cell not be directly to GLP-2 in the in the that the transfected GLP-2 receptor to caspase activation and apoptosis in heterologous cells in the presence of GLP-2 suggest that intestinal cells expressing the endogenous GLP-2R also be from cell death with to in The that GLP-2 cell survival and reduces caspase activation evidence direct activation of GLP-2 receptor signaling to signaling regulating apoptosis in of the signaling mechanisms the coupling of the GLP-2 receptor to inhibition of caspase and cell survival of for of cell death in the mucosal epithelium of the gastrointestinal GLP-2 is the of a the of and NPS

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.