Nonstructural Protein 5B Promotes Degradation of the NORE1A Tumor Suppressor to Facilitate Hepatitis C Virus Replication

Hepatology. 2017 May;65(5):1462-1477. doi: 10.1002/hep.29049. Epub 2017 Mar 30.

Abstract

Hepatitis C virus (HCV) infection is a common risk factor for the development of liver cancer. The molecular mechanisms underlying this effect are only partially understood. Here, we show that the HCV protein, nonstructural protein (NS) 5B, directly binds to the tumor suppressor, NORE1A (RASSF5), and promotes its proteosomal degradation. In addition, we show that NORE1A colocalizes to sites of HCV viral replication and suppresses the replication process. Thus, NORE1A has antiviral activity, which is specifically antagonized by NS5B. Moreover, the suppression of NORE1A protein levels correlated almost perfectly with elevation of Ras activity in primary human samples. Therefore, NORE1A inactivation by NS5B may be essential for maximal HCV replication and may make a major contribution to HCV-induced liver cancer by shifting Ras signaling away from prosenescent/proapoptotic signaling pathways.

Conclusion: HCV uses NS5B to specifically suppress NORE1A, facilitating viral replication and elevated Ras signaling. (Hepatology 2017;65:1462-1477).

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carcinoma, Hepatocellular / virology
  • Down-Regulation
  • HEK293 Cells
  • Hepacivirus / physiology*
  • Humans
  • Liver / metabolism
  • Liver / virology
  • Liver Neoplasms / virology
  • Monomeric GTP-Binding Proteins / metabolism*
  • Proteasome Endopeptidase Complex / metabolism
  • Viral Nonstructural Proteins / metabolism*
  • Virus Replication*

Substances

  • NS-5 protein, hepatitis C virus
  • RASSF5 protein, human
  • Viral Nonstructural Proteins
  • Proteasome Endopeptidase Complex
  • Monomeric GTP-Binding Proteins