title: Myocardial loss of IRS1 and IRS2 causes heart failure and is controlled by p38α MAPK during insulin resistance.
abstract: Cardiac failure is a major cause of death in patients with type 2 diabetes, but the molecular mechanism that links diabetes to heart failure remains unclear. Insulin resistance is a hallmark of type 2 diabetes, and insulin receptor substrates 1 and 2 (IRS1 and IRS2) are the major insulin-signaling components regulating cellular metabolism and survival. To determine the role of IRS1 and IRS2 in the heart and examine whether hyperinsulinemia causes myocardial insulin resistance and cellular dysfunction via IRS1 and IRS2, we generated heart-specific IRS1 and IRS2 gene double-knockout (H-DKO) mice and liver-specific IRS1 and IRS2 double-knockout (L-DKO) mice. H-DKO mice had reduced ventricular mass; developed cardiac apoptosis, fibrosis, and failure; and showed diminished Akt→forkhead box class O-1 signaling that was accompanied by impaired cardiac metabolic gene expression and reduced ATP content. L-DKO mice had decreased cardiac IRS1 and IRS2 proteins and exhibited features of heart failure, with impaired cardiac energy metabolism gene expression and activation of p38α mitogen-activated protein kinase (p38). Using neonatal rat ventricular cardiomyocytes, we further found that chronic insulin exposure reduced IRS1 and IRS2 proteins and prevented insulin action through activation of p38, revealing a fundamental mechanism of cardiac dysfunction during insulin resistance and type 2 diabetes.
authors.affiliation: Division of Molecular Cardiology, Department of Medicine, College of Medicine, Texas A&M University Health Science Center, and Scott & White, Central Texas Veterans Health Care System, Temple, Texas.
authors.forename: Yajuan
authors.initials: Y
authors.lastname: Qi
authors.forename: Zihui
authors.initials: Z
authors.lastname: Xu
authors.forename: Qinglei
authors.initials: Q
authors.lastname: Zhu
authors.forename: Candice
authors.initials: C
authors.lastname: Thomas
authors.forename: Rajesh
authors.initials: R
authors.lastname: Kumar
authors.forename: Hao
authors.initials: H
authors.lastname: Feng
authors.forename: David E
authors.initials: DE
authors.lastname: Dostal
authors.forename: Morris F
authors.initials: MF
authors.lastname: White
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Baker
authors.forename: Shaodong
authors.initials: S
authors.lastname: Guo
mesh_terms: D000818:Animals; D004734:Energy Metabolism / Q000235:genetics; D006333:Heart Failure / Q000209:etiology*; D006946:Hyperinsulinism / Q000503:physiopathology*; D007328:Insulin / Q000502:physiology; D055504:Insulin Receptor Substrate Proteins / Q000172:deficiency*; D007333:Insulin Resistance / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D048308:Mitogen-Activated Protein Kinase 14 / Q000502:physiology*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D051057:Proto-Oncogene Proteins c-akt; D048308:Mitogen-Activated Protein Kinase 14