title: Insulin elicits a ROS-activated and an IP₃-dependent Ca²⁺ release, which both impinge on GLUT4 translocation.
abstract: Insulin signaling includes generation of low levels of H2O2; however, its origin and contribution to insulin-stimulated glucose transport are unknown. We tested the impact of H2O2 on insulin-dependent glucose transport and GLUT4 translocation in skeletal muscle cells. H2O2 increased the translocation of GLUT4 with an exofacial Myc-epitope tag between the first and second transmembrane domains (GLUT4myc), an effect additive to that of insulin. The anti-oxidants N-acetyl L-cysteine and Trolox, the p47(phox)-NOX2 NADPH oxidase inhibitory peptide gp91-ds-tat or p47(phox) knockdown each reduced insulin-dependent GLUT4myc translocation. Importantly, gp91-ds-tat suppressed insulin-dependent H2O2 production. A ryanodine receptor (RyR) channel agonist stimulated GLUT4myc translocation and insulin stimulated RyR1-mediated Ca(2+) release by promoting RyR1 S-glutathionylation. This pathway acts in parallel to insulin-mediated stimulation of inositol-1,4,5-trisphosphate (IP3)-activated Ca(2+) channels, in response to activation of phosphatidylinositol 3-kinase and its downstream target phospholipase C, resulting in Ca(2+) transfer to the mitochondria. An inhibitor of IP3 receptors, Xestospongin B, reduced both insulin-dependent IP3 production and GLUT4myc translocation. We propose that, in addition to the canonical α,β phosphatidylinositol 3-kinase to Akt pathway, insulin engages both RyR-mediated Ca(2+) release and IP3-receptor-mediated mitochondrial Ca(2+) uptake, and that these signals jointly stimulate glucose uptake.
authors.affiliation: Centro de estudios Moleculares de la Célula, Facultad de Medicina; Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.
authors.forename: Ariel
authors.initials: A
authors.lastname: Contreras-Ferrat
authors.forename: Paola
authors.initials: P
authors.lastname: Llanos
authors.forename: César
authors.initials: C
authors.lastname: Vásquez
authors.forename: Alejandra
authors.initials: A
authors.lastname: Espinosa
authors.forename: César
authors.initials: C
authors.lastname: Osorio-Fuentealba
authors.forename: Manuel
authors.initials: M
authors.lastname: Arias-Calderon
authors.forename: Sergio
authors.initials: S
authors.lastname: Lavandero
authors.forename: Amira
authors.initials: A
authors.lastname: Klip
authors.forename: Cecilia
authors.initials: C
authors.lastname: Hidalgo
authors.forename: Enrique
authors.initials: E
authors.lastname: Jaimovich
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D051275:Glucose Transporter Type 4 / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D051275:Glucose Transporter Type 4; D007328:Insulin; D008562:Membrane Glycoproteins; D017382:Reactive Oxygen Species; D015544:Inositol 1,4,5-Trisphosphate; D006861:Hydrogen Peroxide; C500593:Cybb protein, rat; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D002118:Calcium
keywords: Ca2+ transient; Inositol 1,4,5-trisphosphate; Metabolic control; NOX2; RyR1; Skeletal muscle