Hepatitis C virus nonstructural protein 5A favors upregulation of gluconeogenic and lipogenic gene expression leading towards insulin resistance: a metabolic syndrome

Arch Virol. 2014 May;159(5):1017-25. doi: 10.1007/s00705-013-1892-3. Epub 2013 Nov 16.

Abstract

Chronic hepatitis C is a lethal blood-borne infection often associated with a number of pathologies such as insulin resistance and other metabolic abnormalities. Insulin is a key hormone that regulates the expression of metabolic pathways and favors homeostasis. In this study, we demonstrated the molecular mechanism of hepatitis C virus (HCV) nonstructural protein 5A (NS5A)-induced metabolic dysregulation. We showed that transient expression of HCV NS5A in human hepatoma cells increased lipid droplet formation through enhanced lipogenesis. We also showed increased transcriptional expression of peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α and diacylglycerol acyltransferase-1 (DGAT-1) in NS5A-expressing cells. On the other hand, there was significantly reduced transcriptional expression of microsomal triglyceride transfer protein (MTP) and peroxisome proliferator-activated receptor γ (PPARγ) in cells expressing HCV NS5A. Furthermore, increased gluconeogenic gene expression was observed in HCV-NS5A-expressing cells. In addition, it was also shown that HCV-NS5A-expressing hepatoma cells show serine phosphorylation of IRS-1, thereby hampering metabolic activity and contributing to insulin resistance. Therefore, this study reveals that HCV NS5A is involved in enhanced gluconeogenic and lipogenic gene expression, which triggers metabolic abnormality and impairs insulin signaling pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carcinoma, Hepatocellular / metabolism
  • Cell Line, Tumor
  • Gene Expression Regulation
  • Gluconeogenesis / physiology*
  • Hepacivirus / metabolism*
  • Humans
  • Insulin Receptor Substrate Proteins / genetics
  • Insulin Receptor Substrate Proteins / metabolism
  • Insulin Resistance
  • Lipogenesis / physiology*
  • Liver Neoplasms / metabolism
  • Signal Transduction
  • Viral Nonstructural Proteins / physiology*

Substances

  • IRS1 protein, human
  • Insulin Receptor Substrate Proteins
  • Viral Nonstructural Proteins