OCIAD1 is a host mitochondrial substrate of the hepatitis C virus NS3-4A protease.

Huong T L Tran,Kenichi Morikawa,Manfredo Quadroni,Thomas Pietschmann,Markus H Heim,François Penin,Viet Loan Dao Thi,Anggakusuma Anggakusuma,Rose Zibi,Jérôme Gouttenoire,Darius Moradpour,Eve-Isabelle Pecheur

doi:10.1371/journal.pone.0236447

Abstract

The hepatitis C virus (HCV) nonstructural protein 3-4A (NS3-4A) protease is a key component of the viral replication complex and the target of protease inhibitors used in current clinical practice. By cleaving and thereby inactivating selected host factors it also plays a role in the persistence and pathogenesis of hepatitis C. Here, we describe ovarian cancer immunoreactive antigen domain containing protein 1 (OCIAD1) as a novel cellular substrate of the HCV NS3-4A protease. OCIAD1 was identified by quantitative proteomics involving stable isotopic labeling using amino acids in cell culture coupled with mass spectrometry. It is a poorly characterized membrane protein believed to be involved in cancer development. OCIAD1 is cleaved by the NS3-4A protease at Cys 38, close to a predicted transmembrane segment. Cleavage was observed in heterologous expression systems, the replicon and cell culture-derived HCV systems, as well as in liver biopsies from patients with chronic hepatitis C. NS3-4A proteases from diverse hepacivirus species efficiently cleaved OCIAD1. The subcellular localization of OCIAD1 on mitochondria was not altered by NS3-4A-mediated cleavage. Interestingly, OCIAD2, a homolog of OCIAD1 with a cysteine residue in a similar position and identical subcellular localization, was not cleaved by NS3-4A. Domain swapping experiments revealed that the sequence surrounding the cleavage site as well as the predicted transmembrane segment contribute to substrate selectivity. Overexpression as well as knock down and rescue experiments did not affect the HCV life cycle in vitro, raising the possibility that OCIAD1 may be involved in the pathogenesis of hepatitis C in vivo.

Highlights

Hepatitis C virus (HCV) infects about 70 million people and represents a major health burden worldwide [1]
To identify new cellular substrates of the HCV nonstructural protein 3-4A (NS3-4A) protease, we have previously carried out two proteomics screens involving SILAC coupled with mass spectrometry [13]
In addition to glutathione peroxidase 8 (GPx8), which has been described previously [13], these two independent screens performed in cells inducibly expressing NS3-4A have identified OCIAD1 as a potential cellular substrate of the viral protease

Summary

Introduction

Hepatitis C virus (HCV) infects about 70 million people and represents a major health burden worldwide [1]. The nonstructural protein 3-4A (NS3-4A) protease is a key component of the viral replication complex and the target of protease inhibitors used in current clinical practice. By cleaving and thereby inactivating selected host factors it plays a role in the persistence and pathogenesis of hepatitis C [5, 6]. It has been shown to suppress host innate immune responses by cleaving mitochondrial antiviral signaling protein (MAVS) [7] and TIR domain-containing adaptor inducing interferon-β (TRIF) [8], two crucial adaptor molecules in the retinoic acid-inducible gene I (RIG-I) and Toll-like receptor 3 (TLR3) pathway, respectively. The NS3-4A protease has been reported to modulate epidermal growth factor receptor signaling by cleaving T-cell protein tyrosine phosphatase (TC-PTP) [9]. More recent studies have identified DNA damage-binding protein 1 (DDB1) [10], Riplet [11], complement component 4γ (C4γ) [12], glutathione peroxidase 8 (GPx8) [13], importin β1 [14] and Werner syndrome protein [15] as targets of the NS3-4A protease

Methods

Results

Conclusion