Association of Hepatitis C Virus Replication with the Catecholamine Biosynthetic Pathway.

George Mpekoulis,Katerina I Kalliampakou,Alice G Vassiliou,Dido Vassilacopoulou,Vasileiοs Siozos,Vassilina Tsopela,Constantinos D Sideris,Georgios Panos,Diamantis C Sideris,Efseveia Frakolaki,Niki Vassilaki

doi:10.3390/v13112139

Abstract

A bidirectional negative relationship between Hepatitis C virus (HCV) replication and gene expression of the catecholamine biosynthetic enzyme L-Dopa decarboxylase (DDC) was previously shown in the liver and attributed at least to an association of DDC with phosphatidylinositol 3-kinase (PI3K). Here, we report that the biosynthesis and uptake of catecholamines restrict HCV replication in hepatocytes, while HCV has developed ways to reduce catecholamine production. By employing gene silencing, chemical inhibition or induction of the catecholamine biosynthetic and metabolic enzymes and transporters, and by applying the substrates or the products of the respective enzymes, we unravel the role of the different steps of the pathway in viral infection. We also provide evidence that the effect of catecholamines on HCV is strongly related with oxidative stress that is generated by their autoxidation in the cytosol, while antioxidants or treatments that lower cytosolic catecholamine levels positively affect the virus. To counteract the effect of catecholamines, HCV, apart from the already reported effects on DDC, causes the down-regulation of tyrosine hydroxylase that encodes the rate-limiting enzyme of catecholamine biosynthesis and suppresses dopamine beta-hydroxylase mRNA and protein amounts, while increasing the catecholamine degradation enzyme monoamine oxidase. Moreover, the NS4B viral protein is implicated in the effect of HCV on the ratio of the ~50 kDa DDC monomer and a ~120 kDa DDC complex, while the NS5A protein has a negative effect on total DDC protein levels.

Highlights

IntroductionThe global epidemic of Hepatitis C virus (HCV) is distributed unevenly, with the Eastern Mediterranean region and Europe having the highest prevalence [1,2,3]
To silence Dopa decarboxylase (DDC), human hepatoma Huh7.5 cells were electroporated with an shDDC plasmid vector or a scramble negative control short hairpin RNA (shRNA) plasmid and subsequently infected with Jc1 or the reporter JcR2A virus
Tion [7], hereby we performed gene silencing to confirm the negative effect of DDC on Hepatitis C virus (HCV) replication and to examine whether this effect is mediated by the biosynthetic role of DDC

Summary

Introduction

The global epidemic of HCV is distributed unevenly, with the Eastern Mediterranean region and Europe having the highest prevalence [1,2,3]. The HCV genome, a positive sense, single-stranded RNA, encodes a single polyprotein of ~3000 amino acids [4,5]. This is proteolytically cleaved into structural proteins (core, E1 and E2) that form the viral capsid, p7, which is necessary for the assembly and release of infectious virions, and non-structural 4.0/). (NS) proteins (NS2, NS3, NS4A, NS4B, NS5A and NS5B), orchestrating HCV replication in endoplasmic reticulum (ER) membrane protrusions [6].

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