title: GLP-2 rapidly activates divergent intracellular signaling pathways involved in intestinal cell survival and proliferation in neonatal piglets.
abstract: We previously demonstrated the dose-dependent glucagon-like peptide (GLP)-2 activation of intracellular signals associated with increased epithelial cell survival and proliferation in the neonatal intestine. Our current aim was to quantify the acute, temporal GLP-2 activation of these key intracellular signals and relate this to changes in epithelial cell survival and proliferation in the neonatal intestine. We studied 29 total parenteral nutrition-fed neonatal piglets infused intravenously with either saline (control) or human GLP-2 (420 micromol.kg(-1).h(-1)) for 1, 4, or 48 h. GLP-2 infusion increased small intestinal weight, DNA and protein content, and villus height at 48 h, but not at 1 or 4 h. Intestinal crypt and villus apoptosis decreased and crypt cell proliferation and protein synthesis increased linearly with duration of GLP-2 infusion, but were statistically different from controls only after 48 h. Before the morphological and cellular kinetic changes, GLP-2 rapidly activated putative GLP-2 receptor downstream signals within 1-4 h, including phosphorylation of protein kinase A, protein kinase B, extracellular signal-regulated kinase 1/2, and the transcription factors cAMP response element-binding protein and c-Fos. GLP-2 rapidly suppressed caspase-3 activation and upregulated Bcl-2 abundance within 1 h, whereas there was an increase in apoptosis inhibitors X-linked inhibitor of apoptosis at 1 h and cellular inhibitor of apoptosis-2 at 4 and 48 h. We also show that the increased c-Fos and reduced active caspase-3 immunostaining after GLP-2 infusion was localized in epithelial cells. We conclude that GLP-2-induced activation of intracellular signals involved in both cell survival and proliferation occurs rapidly and precedes the trophic cellular kinetic effects that occur later in intestinal epithelial cells.
authors.affiliation: Children's Nutrition Research Center, 1100 Bates St., Houston, TX 77030, USA. dburrin@bcm.tmc.edu
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Burrin
authors.forename: Barbara
authors.initials: B
authors.lastname: Stoll
authors.forename: Xinfu
authors.initials: X
authors.lastname: Guan
authors.forename: Liwei
authors.initials: L
authors.lastname: Cui
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Chang
authors.forename: Darryl
authors.initials: D
authors.lastname: Hadsell
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D053767:Glucagon-Like Peptide 2 / Q000008:administration & dosage / Q000494:pharmacology*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D007422:Intestines / Q000166:cytology / Q000187:drug effects*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013552:Swine; D013997:Time Factors
chemical_list: D053767:Glucagon-Like Peptide 2; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D038362:Glycogen Synthase Kinase 3