Insulin activation of mitogen-activated protein kinases Erk1,2 is amplified via beta-adrenergic receptor expression and requires the integrity of the Tyr350 of the receptor.
Insulin activates a complex set of intracellular responses, including the activation of mitogen-activated protein kinases Erk1,2. The counterregulatory actions of insulin on catecholamine action are well known and include phosphorylation of the beta(2)-adrenergic receptor on Tyr(350), Tyr(354), and Tyr(364) in the C-terminal cytoplasmic domain, as well as enhanced sequestration of the beta(2)-adrenergic receptor. Both beta-adrenergic agonists and insulin provoke sequestration of beta(2)-adrenergic receptors in a synergistic manner. In the current work, cross-talk between insulin action and beta(2)-adrenergic receptors revealed that insulin activation of Erk1,2 was amplified via beta(2)-adrenergic receptors. In Chinese hamster ovary cells, expression of beta(2)-adrenergic receptors enhanced 5-10-fold the activation of Erk1,2 by insulin and prolonged the activation, the greatest enhancement occurring at 5 min post-insulin. The potentiation of insulin signaling on Erk1,2 was proportional to the level of expression of beta(2)-adrenergic receptor. The potentiation of insulin signaling requires the integrity of Tyr(350) of the beta(2)-adrenergic receptor, a residue phosphorylated in response to insulin. beta(2)-adrenergic receptors with a Y350F mutation failed to potentiate insulin activation of Erk1,2. Expression of the C-terminal domain of the beta(2)-adrenergic receptor (Pro(323)-Leu(418)) in cells expressing the intact beta(2)-adrenergic receptor acts as a dominant negative, blocking the potentiation of insulin activation of Erk1,2 via the beta(2)-adrenergic receptor. Blockade of beta(2)-adrenergic receptor sequestration does not alter the ability of the beta(2)-adrenergic receptor to potentiate insulin action on Erk1,2. We propose a new paradigm in which a G-protein-linked receptor, such as the beta(2)-adrenergic receptor, itself acts as a receptor-based scaffold via its binding site for Src homology 2 domains, facilitating signaling of the mitogen-activated protein kinase pathway by insulin.
Department of Physiology and Biophysics, Diabetes and Metabolic Diseases Research Program, University Medical Center, State University of New York, Stony Brook, New York 11794-8661, USA.
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D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D016466:CHO Cells; D002867:Chromones / Q000494:pharmacology; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology; D008856:Microscopy, Fluorescence; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D017434:Protein Structure, Tertiary; D011943:Receptors, Adrenergic, beta / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism*
D000318:Adrenergic beta-Agonists; D002867:Chromones; D007328:Insulin; D007545:Isoproterenol; D020928:Mitogen-Activated Protein Kinases; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011943:Receptors, Adrenergic, beta; D011993:Recombinant Fusion Proteins; D014443:Tyrosine; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one