title: Bradykinin augments insulin-stimulated glucose transport in rat adipocytes via endothelial nitric oxide synthase-mediated inhibition of Jun NH2-terminal kinase.
abstract: An increase in bradykinin has been suggested to contribute to the enhanced insulin sensitivity observed in the presence of ACE inhibitors. To investigate a potential direct, nonvascular effect on an insulin target tissue, the effect of bradykinin on glucose uptake and insulin signaling was studied in primary rat adipocytes. Whereas basal glucose uptake was not altered, bradykinin augmented insulin-stimulated glucose uptake twofold, which was blocked by HOE-140, a bradykinin B2 receptor antagonist. The bradykinin effect on glucose uptake was nitric oxide (NO) dependent, mimicked by NO donors and absent in adipocytes from endothelial NO synthase-/- mice. Investigation of insulin signaling revealed that bradykinin enhanced insulin receptor substrate-1 (IRS-1) Tyr phosphorylation, Akt/protein kinase B phosphorylation, and GLUT4 translocation. In contrast, insulin-stimulated extracellular signal-regulated kinase1/2 and Jun NH2-terminal kinase (JNK) activation were decreased in the presence of bradykinin, accompanied by decreased IRS-1 Ser307 phosphorylation. Furthermore, bradykinin did not enhance insulin action in the presence of the JNK inhibitor, SP-600125, or in adipocytes from JNK1-/- mice. These data indicate that bradykinin enhances insulin sensitivity in adipocytes via an NO-dependent pathway that acts by modulating the feedback inhibition of insulin signaling at the level of IRS-1.
authors.affiliation: Department of Medicine and Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON, Canada M5G 1X6.
authors.forename: Kristin M
authors.initials: KM
authors.lastname: Beard
authors.forename: Huogen
authors.initials: H
authors.lastname: Lu
authors.forename: Karen
authors.initials: K
authors.lastname: Ho
authors.forename: I George
authors.initials: IG
authors.lastname: Fantus
mesh_terms: D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology / Q000502:physiology*; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4 / Q000378:metabolism; D019811:Hydroxylamine / Q000494:pharmacology; D007328:Insulin / Q000502:physiology*; D055504:Insulin Receptor Substrate Proteins; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008297:Male; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010750:Phosphoproteins / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D043782:Receptor, Bradykinin B2 / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology
chemical_list: D051275:Glucose Transporter Type 4; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526295:Irs1 protein, mouse; C526296:Irs1 protein, rat; D010750:Phosphoproteins; D043782:Receptor, Bradykinin B2; D019811:Hydroxylamine; D052250:Nitric Oxide Synthase Type III; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D005947:Glucose; D001920:Bradykinin