Cardiac insulin resistance and microRNA modulators

Exp Diabetes Res. 2012:2012:654904. doi: 10.1155/2012/654904. Epub 2011 Jul 31.

Abstract

Cardiac insulin resistance is a metabolic and functional disorder that is often associated with obesity and/or the cardiorenal metabolic syndrome (CRS), and this disorder may be accentuated by chronic alcohol consumption. In conditions of over-nutrition, increased insulin (INS) and angiotensin II (Ang II) activate mammalian target for rapamycin (mTOR)/p70 S6 kinase (S6K1) signaling, whereas chronic alcohol consumption inhibits mTOR/S6K1 activation in cardiac tissue. Although excessive activation of mTOR/S6K1 induces cardiac INS resistance via serine phosphorylation of INS receptor substrates (IRS-1/2), it also renders cardioprotection via increased Ang II receptor 2 (AT2R) upregulation and adaptive hypertrophy. In the INS-resistant and hyperinsulinemic Zucker obese (ZO) rat, a rodent model for CRS, activation of mTOR/S6K1signaling in cardiac tissue is regulated by protective feed-back mechanisms involving mTOR↔AT2R signaling loop and profile changes of microRNA that target S6K1. Such regulation may play a role in attenuating progressive heart failure. Conversely, alcohol-mediated inhibition of mTOR/S6K1, down-regulation of INS receptor and growth-inhibitory mir-200 family, and upregulation of mir-212 that promotes fetal gene program may exacerbate CRS-related cardiomyopathy.

Publication types

  • Review

MeSH terms

  • Alcohol Drinking / adverse effects
  • Animals
  • Cardiomyopathies / etiology
  • Cardiomyopathies / genetics
  • Cardiomyopathies / metabolism*
  • Cardiomyopathies / physiopathology
  • Humans
  • Insulin / metabolism*
  • Insulin Resistance* / genetics
  • Mechanistic Target of Rapamycin Complex 1
  • MicroRNAs / metabolism*
  • Multiprotein Complexes
  • Myocardium / metabolism*
  • Overnutrition / complications
  • Overnutrition / metabolism
  • Proteins / metabolism
  • Receptors, Angiotensin / metabolism
  • Ribosomal Protein S6 Kinases, 70-kDa / metabolism
  • Risk Factors
  • Signal Transduction* / genetics
  • TOR Serine-Threonine Kinases / metabolism

Substances

  • Insulin
  • MicroRNAs
  • Multiprotein Complexes
  • Proteins
  • Receptors, Angiotensin
  • MTOR protein, human
  • Mechanistic Target of Rapamycin Complex 1
  • Ribosomal Protein S6 Kinases, 70-kDa
  • TOR Serine-Threonine Kinases
  • ribosomal protein S6 kinase, 70kD, polypeptide 1