title: Essential role of protein kinase C zeta in the impairment of insulin-induced glucose transport in IRS-2-deficient brown adipocytes.
abstract: Insulin receptor substrate-2-deficient (IRS-2(-/-)) mice develop type 2 diabetes. We have investigated the molecular mechanisms by which IRS-2(-/-) immortalized brown adipocytes showed an impaired response to insulin in inducing GLUT4 translocation and glucose uptake. IRS-2-associated phosphatidylinositol 3-kinase (PI 3-kinase) activity was blunted in IRS-2(-/-) cells, total PI 3-kinase activity being reduced by 30%. Downstream, activation of protein kinase C (PKC) zeta was abolished in IRS-2(-/-) cells. Reconstitution with retroviral IRS-2 restores IRS-2/PI 3-kinase/PKC zeta signalling, as well as glucose uptake. Wild-type cells expressing a kinase-inactive mutant of PKC zeta lack GLUT4 translocation and glucose uptake. Our results support the essential role played by PKC zeta in the insulin resistance and impaired glucose uptake observed in IRS-2-deficient brown adipocytes.
authors.affiliation: Departamento de Bioquímica y Biología Molecular/Instituto de Bioquímica, Centro Mixto CSIC/UCM, Facultad de Farmacia, Universidad Complutense, 28040 Madrid, Spain.
authors.forename: Mónica
authors.initials: M
authors.lastname: Arribas
authors.forename: Angela M
authors.initials: AM
authors.lastname: Valverde
authors.forename: Deborah
authors.initials: D
authors.lastname: Burks
authors.forename: Johannes
authors.initials: J
authors.lastname: Klein
authors.forename: Robert V
authors.initials: RV
authors.lastname: Farese
authors.forename: Morris F
authors.initials: MF
authors.lastname: White
authors.forename: Manuel
authors.initials: M
authors.lastname: Benito
mesh_terms: D017667:Adipocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D002001:Adipose Tissue, Brown / Q000166:cytology; D000818:Animals; D001692:Biological Transport; D002478:Cells, Cultured; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D018345:Mice, Knockout; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000502:physiology*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000502:physiology*; D015398:Signal Transduction; D000099221:Protein Kinase C zeta
chemical_list: D005947:Glucose; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins; D011493:Protein Kinase C; D000099221:Protein Kinase C zeta; C526298:Irs2 protein, mouse