title: Nonstructural 5A Protein of Hepatitis C Virus Regulates Soluble Resistance-Related Calcium-Binding Protein Activity for Viral Propagation.
abstract: Hepatitis C virus (HCV) is a major cause of chronic liver disease and is highly dependent on cellular proteins for virus propagation. To identify the cellular factors involved in HCV propagation, we recently performed protein microarray assays using the HCV nonstructural 5A (NS5A) protein as a probe. Of 90 cellular protein candidates, we selected the soluble resistance-related calcium-binding protein (sorcin) for further characterization. Sorcin is a calcium-binding protein and is highly expressed in certain cancer cells. We verified that NS5A interacted with sorcin through domain I of NS5A, and phosphorylation of the threonine residue 155 of sorcin played a crucial role in protein interaction. Small interfering RNA (siRNA)-mediated knockdown of sorcin impaired HCV propagation. Silencing of sorcin expression resulted in a decrease of HCV assembly without affecting HCV RNA and protein levels. We further demonstrated that polo-like kinase 1 (PLK1)-mediated phosphorylation of sorcin was increased by NS5A. We showed that both phosphorylation and calcium-binding activity of sorcin were required for HCV propagation. These data indicate that HCV modulates sorcin activity via NS5A protein for its own propagation.
  
  
  OBJECTIVE
  Sorcin is a calcium-binding protein and regulates intracellular calcium homeostasis. HCV NS5A interacts with sorcin, and phosphorylation of sorcin is required for protein interaction. Gene silencing of sorcin impaired HCV propagation at the assembly step of the HCV life cycle. Sorcin is phosphorylated by PLK1 via protein interaction. We showed that sorcin interacted with both NS5A and PLK1, and PLK1-mediated phosphorylation of sorcin was increased by NS5A. Moreover, calcium-binding activity of sorcin played a crucial role in HCV propagation. These data provide evidence that HCV regulates host calcium metabolism for virus propagation, and thus manipulation of sorcin activity may represent a novel therapeutic target for HCV.
authors.affiliation: National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang, South Korea.
authors.forename: Giao V Q
authors.initials: GV
authors.lastname: Tran
authors.affiliation: National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang, South Korea.
authors.forename: Trang T D
authors.initials: TT
authors.lastname: Luong
authors.affiliation: National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang, South Korea Korea National Institute of Health, Cheongwon-gun, South Korea.
authors.forename: Eun-Mee
authors.initials: EM
authors.lastname: Park
authors.affiliation: National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang, South Korea.
authors.forename: Jong-Wook
authors.initials: JW
authors.lastname: Kim
authors.affiliation: National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang, South Korea.
authors.forename: Jae-Woong
authors.initials: JW
authors.lastname: Choi
authors.affiliation: National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang, South Korea.
authors.forename: Chorong
authors.initials: C
authors.lastname: Park
authors.affiliation: National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang, South Korea.
authors.forename: Yun-Sook
authors.initials: YS
authors.lastname: Lim
authors.affiliation: National Research Laboratory of Hepatitis C Virus and Ilsong Institute of Life Science, Hallym University, Anyang, South Korea sbhwang@hallym.ac.kr.
authors.forename: Soon B
authors.initials: SB
authors.lastname: Hwang
mesh_terms: D002135:Calcium-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D016174:Hepacivirus / Q000254:growth & development / Q000502:physiology*; D054884:Host-Pathogen Interactions; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D019065:Virus Assembly; D012324:RNA-Dependent RNA Polymerase
chemical_list: D002135:Calcium-Binding Proteins; D017361:Viral Nonstructural Proteins; C503113:SRI protein, human; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase