Hepatitis C Virus Indirectly Disrupts DNA Damage-Induced p53 Responses by Activating Protein Kinase R

ABSTRACT Many DNA tumor viruses promote cellular transformation by inactivating the critically important tumor suppressor protein p53. In contrast, it is not known whether p53 function is disrupted by hepatitis C virus (HCV), a unique, oncogenic RNA virus that is the leading infectious cause of live...

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Autores principales:	Jonathan K. Mitchell, Bentley R. Midkiff, Benjamin Israelow, Matthew J. Evans, Robert E. Lanford, Christopher M. Walker, Stanley M. Lemon, David R. McGivern
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2017
Materias:	PKR hepatitis C virus liver cancer p53 translation Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/9c7aab5b79d24bc7ab1c2afe955f3b68
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spelling	oai:doaj.org-article:9c7aab5b79d24bc7ab1c2afe955f3b682021-11-15T15:50:59ZHepatitis C Virus Indirectly Disrupts DNA Damage-Induced p53 Responses by Activating Protein Kinase R10.1128/mBio.00121-172150-7511https://doaj.org/article/9c7aab5b79d24bc7ab1c2afe955f3b682017-05-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00121-17https://doaj.org/toc/2150-7511ABSTRACT Many DNA tumor viruses promote cellular transformation by inactivating the critically important tumor suppressor protein p53. In contrast, it is not known whether p53 function is disrupted by hepatitis C virus (HCV), a unique, oncogenic RNA virus that is the leading infectious cause of liver cancer in many regions of the world. Here we show that HCV-permissive, liver-derived HepG2 cells engineered to constitutively express microRNA-122 (HepG2/miR-122 cells) have normal p53-mediated responses to DNA damage and that HCV replication in these cells potently suppresses p53 responses to etoposide, an inducer of DNA damage, or nutlin-3, an inhibitor of p53 degradation pathways. Upregulation of p53-dependent targets is consequently repressed within HCV-infected cells, with potential consequences for cell survival. Despite this, p53 function is not disrupted by overexpression of the complete HCV polyprotein, suggesting that altered p53 function may result from the host response to viral RNA replication intermediates. Clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9-mediated ablation of double-stranded RNA (dsRNA)-activated protein kinase R (PKR) restored p53 responses while boosting HCV replication, showing that p53 inhibition results directly from viral activation of PKR. The hepatocellular abundance of phosphorylated PKR is elevated in HCV-infected chimpanzees, suggesting that PKR activation and consequent p53 inhibition accompany HCV infection in vivo. These findings reveal a feature of the host response to HCV infection that may contribute to hepatocellular carcinogenesis. IMPORTANCE Chronic infection with hepatitis C virus (HCV) is the leading cause of liver cancer in most developed nations. However, the mechanisms whereby HCV infection promotes carcinogenesis remain unclear. Here, we demonstrate that HCV infection inhibits the activation of p53 following DNA damage. Contrary to previous reports, HCV protein expression is insufficient to inhibit p53. Rather, p53 inhibition is mediated by cellular protein kinase R (PKR), which is activated by HCV RNA replication and subsequently suppresses global protein synthesis. These results redefine our understanding of how HCV infection influences p53 function. We speculate that persistent disruption of p53-mediated DNA damage responses may contribute to hepatocellular carcinogenesis in chronically infected individuals.Jonathan K. MitchellBentley R. MidkiffBenjamin IsraelowMatthew J. EvansRobert E. LanfordChristopher M. WalkerStanley M. LemonDavid R. McGivernAmerican Society for MicrobiologyarticlePKRhepatitis C virusliver cancerp53translationMicrobiologyQR1-502ENmBio, Vol 8, Iss 2 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	PKR hepatitis C virus liver cancer p53 translation Microbiology QR1-502
spellingShingle	PKR hepatitis C virus liver cancer p53 translation Microbiology QR1-502 Jonathan K. Mitchell Bentley R. Midkiff Benjamin Israelow Matthew J. Evans Robert E. Lanford Christopher M. Walker Stanley M. Lemon David R. McGivern Hepatitis C Virus Indirectly Disrupts DNA Damage-Induced p53 Responses by Activating Protein Kinase R
description	ABSTRACT Many DNA tumor viruses promote cellular transformation by inactivating the critically important tumor suppressor protein p53. In contrast, it is not known whether p53 function is disrupted by hepatitis C virus (HCV), a unique, oncogenic RNA virus that is the leading infectious cause of liver cancer in many regions of the world. Here we show that HCV-permissive, liver-derived HepG2 cells engineered to constitutively express microRNA-122 (HepG2/miR-122 cells) have normal p53-mediated responses to DNA damage and that HCV replication in these cells potently suppresses p53 responses to etoposide, an inducer of DNA damage, or nutlin-3, an inhibitor of p53 degradation pathways. Upregulation of p53-dependent targets is consequently repressed within HCV-infected cells, with potential consequences for cell survival. Despite this, p53 function is not disrupted by overexpression of the complete HCV polyprotein, suggesting that altered p53 function may result from the host response to viral RNA replication intermediates. Clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9-mediated ablation of double-stranded RNA (dsRNA)-activated protein kinase R (PKR) restored p53 responses while boosting HCV replication, showing that p53 inhibition results directly from viral activation of PKR. The hepatocellular abundance of phosphorylated PKR is elevated in HCV-infected chimpanzees, suggesting that PKR activation and consequent p53 inhibition accompany HCV infection in vivo. These findings reveal a feature of the host response to HCV infection that may contribute to hepatocellular carcinogenesis. IMPORTANCE Chronic infection with hepatitis C virus (HCV) is the leading cause of liver cancer in most developed nations. However, the mechanisms whereby HCV infection promotes carcinogenesis remain unclear. Here, we demonstrate that HCV infection inhibits the activation of p53 following DNA damage. Contrary to previous reports, HCV protein expression is insufficient to inhibit p53. Rather, p53 inhibition is mediated by cellular protein kinase R (PKR), which is activated by HCV RNA replication and subsequently suppresses global protein synthesis. These results redefine our understanding of how HCV infection influences p53 function. We speculate that persistent disruption of p53-mediated DNA damage responses may contribute to hepatocellular carcinogenesis in chronically infected individuals.
format	article
author	Jonathan K. Mitchell Bentley R. Midkiff Benjamin Israelow Matthew J. Evans Robert E. Lanford Christopher M. Walker Stanley M. Lemon David R. McGivern
author_facet	Jonathan K. Mitchell Bentley R. Midkiff Benjamin Israelow Matthew J. Evans Robert E. Lanford Christopher M. Walker Stanley M. Lemon David R. McGivern
author_sort	Jonathan K. Mitchell
title	Hepatitis C Virus Indirectly Disrupts DNA Damage-Induced p53 Responses by Activating Protein Kinase R
title_short	Hepatitis C Virus Indirectly Disrupts DNA Damage-Induced p53 Responses by Activating Protein Kinase R
title_full	Hepatitis C Virus Indirectly Disrupts DNA Damage-Induced p53 Responses by Activating Protein Kinase R
title_fullStr	Hepatitis C Virus Indirectly Disrupts DNA Damage-Induced p53 Responses by Activating Protein Kinase R
title_full_unstemmed	Hepatitis C Virus Indirectly Disrupts DNA Damage-Induced p53 Responses by Activating Protein Kinase R
title_sort	hepatitis c virus indirectly disrupts dna damage-induced p53 responses by activating protein kinase r
publisher	American Society for Microbiology
publishDate	2017
url	https://doaj.org/article/9c7aab5b79d24bc7ab1c2afe955f3b68
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Hepatitis C Virus Indirectly Disrupts DNA Damage-Induced p53 Responses by Activating Protein Kinase R

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