Phosphatidylinositol 3-kinase signaling to Akt mediates survival in isolated canine islets of Langerhans.
The isolation of islet cells from the pancreas by enzymatic digestion causes many of these cells to undergo apoptosis. The aim of this work was to investigate the role of phosphatidylinositol 3-kinase (PI3-K)/Akt signaling in mediating the survival of isolated islets. Insulin-like growth factor-1 (IGF-I) was examined as a potential culture media supplement that could rescue isolated islets from their apoptotic fate. Western blot analysis demonstrated that Akt phosphorylation peaks 20 h after routine islet isolation. PI3-K inhibition with wortmannin abolished both basal and IGF-I-mediated Akt phosphorylation. IGF-I did not increase survival of isolated islets under normal conditions but it did have a protective effect against cytokine (TNF-alpha, IL-1beta, INF-gamma)-mediated cell death. The protective effect of IGF-I against cytokine-stimulated apoptosis was blocked by wortmannin. In addition, inhibition of basal levels of PI3-K activity caused a 31% decrease in islet survival, as shown by MTT assay. These results demonstrate that the PI3-K/Akt pathway mediates survival of isolated islets of Langerhans.
Aikin
R
R
Department of Surgery, McGill University, Montreal, Quebec, H3G 1A4, Canada.
Rosenberg
L
L
Maysinger
D
D
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002470:Cell Survival; D002478:Cells, Cultured; D004396:Coloring Agents / Q000494:pharmacology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005452:Fluoresceins / Q000494:pharmacology; D007202:Indicators and Reagents / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D007515:Islets of Langerhans / Q000166:cytology* / Q000378:metabolism; D008856:Microscopy, Fluorescence; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010766:Phosphorylation; D011419:Propidium / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D000077191:Wortmannin
D000730:Androstadienes; D004396:Coloring Agents; D004791:Enzyme Inhibitors; D005452:Fluoresceins; D007202:Indicators and Reagents; D007334:Insulin-Like Growth Factor I; D007371:Interferon-gamma; D007375:Interleukin-1; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D010726:Phosphodiesterase Inhibitors; D011419:Propidium; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D013778:Tetrazolium Salts; D013844:Thiazoles; D014409:Tumor Necrosis Factor-alpha; D000077191:Wortmannin; C022616:thiazolyl blue; C018506:diacetylfluorescein