title: IGF-1 inhibits the mitochondrial apoptosis program in mesangial cells exposed to high glucose.
abstract: The activated insulin-like growth factor-1 receptor (IGF-1R) protects cells from a wide range of apoptotic stimuli. Hyperglycemia promotes the intracellular generation of superoxide anion and hydrogen peroxide, both of which have been linked to the activation of the mitochondrial apoptosis program. Here, we report for the first time that ligand activation of the IGF-1R protects normal human mesangial cells and SV40 murine mesangial cells from the glycol-oxidant-induced apoptosis program. The IGF-1R antiapoptosis program was dependent on the recruitment of both Akt/PKB and the ERK subfamily of mitogen-activated protein kinases. IGF-1 treatment also protected the redox potential of mesangial cells maintained at high ambient glucose concentration, by inhibiting the generation of reactive oxygen intermediates and preserving mitochondrial transmembrane potential. IGF-1R survival signals targeted the Bcl-2 family of proteins to protect against glucose-induced apoptosis and oxidative stress. IGF-1-treated cells exhibited a decrease in the Bax/Bcl-2 ratio; increased phosphorylation/inactivation of Bad at Ser112 and Ser136; inhibition of cytochrome c release; perturbations directionally opposed to the initiation of the apoptosis program. In addition, we demonstrate IGF-1R-activated ERK signaling modules phosphorylate Ser112 of the mitochondrial Bad protein, establishing a direct link between surface IGF-1R and the survival program in mitochondria. Our findings indicate that in mesangial cells maintained at high ambient glucose concentration, IGF-1 activates a survival program that maintains the integrity of mitochondria and prevents the expression of the genetic program for apoptosis.
authors.affiliation: Division of Nephrology, Department of Medicine, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, NJ 07103, USA.
authors.forename: Barinder P S
authors.initials: BP
authors.lastname: Kang
authors.forename: Arunas
authors.initials: A
authors.lastname: Urbonas
authors.forename: Andrew
authors.initials: A
authors.lastname: Baddoo
authors.forename: Stuart
authors.initials: S
authors.lastname: Baskin
authors.forename: Ashwani
authors.initials: A
authors.lastname: Malhotra
authors.forename: Leonard G
authors.initials: LG
authors.lastname: Meggs
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002070:Butadienes / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005920:Glomerular Mesangium / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D005947:Glucose / Q000008:administration & dosage*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D008928:Mitochondria / Q000378:metabolism / Q000502:physiology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors; D017526:Receptor, IGF Type 1 / Q000502:physiology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D002070:Butadienes; D002867:Chromones; D004791:Enzyme Inhibitors; D009025:Morpholines; D009570:Nitriles; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53; C113580:U 0126; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D007334:Insulin-Like Growth Factor I; D045304:Cytochromes c; D017526:Receptor, IGF Type 1; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D005947:Glucose