title: Tumor necrosis factor (TNF)-α-induced repression of GKAP42 protein levels through cGMP-dependent kinase (cGK)-Iα causes insulin resistance in 3T3-L1 adipocytes.
abstract: Insulin receptor substrates (IRSs) have been shown to be major mediators of insulin signaling. Recently, we found that IRSs form high-molecular weight complexes, and here, we identify by yeast two-hybrid screening a novel IRS-1-associated protein: a 42-kDa cGMP-dependent protein kinase-anchoring protein (GKAP42). GKAP42 knockdown in 3T3-L1 adipocytes suppressed insulin-dependent IRS-1 tyrosine phosphorylation and downstream signaling, resulting in suppression of GLUT4 translocation to plasma membrane induced by insulin. In addition, GLUT4 translocation was also suppressed in cells overexpressing GKAP42-N (the IRS-1 binding region of GKAP42), which competed with GKAP42 for IRS-1, indicating that GKAP42 binding to IRS-1 is required for insulin-induced GLUT4 translocation. Long term treatment of 3T3-L1 adipocytes with TNF-α, which induced insulin resistance, significantly decreased the GKAP42 protein level. We then investigated the roles of cGMP-dependent kinase (cGK)-Iα, which bound to GKAP42, in these changes. cGK-Iα knockdown partially rescued TNF-α-induced decrease in GKAP42 and impairment of insulin signals. These data indicated that TNF-α-induced repression of GKAP42 via cGK-Iα caused reduction of insulin-induced IRS-1 tyrosine phosphorylation at least in part. The present study describes analysis of the novel TNF-α-induced pathway, cGK-Iα-GKAP42, which regulates insulin-dependent signals and GLUT4 translocation.
authors.affiliation: From the Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Yasutoshi
authors.initials: Y
authors.lastname: Ando
authors.affiliation: From the Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Shinozawa
authors.affiliation: From the Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Iijima
authors.affiliation: From the Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Bu-Chin
authors.initials: BC
authors.lastname: Yu
authors.affiliation: From the Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Meri
authors.initials: M
authors.lastname: Sone
authors.affiliation: From the Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ooi
authors.affiliation: From the Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Watanaka
authors.affiliation: From the Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Chida
authors.affiliation: From the Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan ahakuno@mail.ecc.u-tokyo.ac.jp.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Hakuno
authors.affiliation: From the Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Takahashi
mesh_terms: D041721:3T3-L1 Cells; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D062965:Cyclic GMP-Dependent Protein Kinase Type I / Q000235:genetics / Q000378:metabolism*; D004351:Drug Resistance; D051275:Glucose Transporter Type 4 / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D015151:Immunoblotting; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D021381:Protein Transport / Q000187:drug effects; D034622:RNA Interference; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D020798:Two-Hybrid System Techniques; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C405330:Gkap1 protein, mouse; D051275:Glucose Transporter Type 4; D007004:Hypoglycemic Agents; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526295:Irs1 protein, mouse; C495693:Slc2a4 protein, mouse; D014409:Tumor Necrosis Factor-alpha; D014443:Tyrosine; D062965:Cyclic GMP-Dependent Protein Kinase Type I
keywords: Adipocyte; Glucose Metabolism; Glucose Transporter Type 4 (GLUT4); Insulin Receptor Substrate 1 (IRS-1); Tumor Necrosis Factor (TNF); Type 2 Diabetes