title: Heat shock protein 72 is associated with the hepatitis C virus replicase complex and enhances viral RNA replication.
abstract: The NS5A protein of the hepatitis C virus (HCV) is an integral component of the viral replicase. It also modulates cellular signaling and perturbs host interferon responses. The multifunctional characteristics of NS5A are mostly attributed to its ability to interact with various cellular proteins. This study aimed to identify the novel cellular factors that interact with NS5A and decipher the significance of this interaction in viral replication. The NS5A-interacting proteins were purified by the tandem affinity purification (TAP) procedure from cells expressing NS5A and identified by mass spectrometry. The chaperone protein Hsp72 was identified herein. In vivo protein-protein interaction was verified by co-immunoprecipitation and an in situ proximity ligation assay. In addition to NS5A, Hsp72 was also associated with other members of the replicase complex, NS3 and NS5B, suggesting that it might be directly involved in the HCV replication complex. Hsp72 plays a positive regulatory role in HCV RNA replication by increasing levels of the replicase complex, which was attributed either to the increased stability of the viral proteins in the replicase complex or to the enhanced translational activity of the internal ribosome entry site of HCV. The fact that the host chaperone protein Hsp72 is involved in HCV RNA replication may represent a therapeutic target for controlling virus production.
authors.affiliation: Institute of Microbiology and Immunology, National Yang-Ming University, Taipei 112, Taiwan.
authors.forename: Yin-Ju
authors.initials: YJ
authors.lastname: Chen
authors.forename: Yu-Hsuan
authors.initials: YH
authors.lastname: Chen
authors.forename: Lu-Ping
authors.initials: LP
authors.lastname: Chow
authors.forename: Ya-Hui
authors.initials: YH
authors.lastname: Tsai
authors.forename: Pei-Hong
authors.initials: PH
authors.lastname: Chen
authors.forename: Chi-Ying F
authors.initials: CY
authors.lastname: Huang
authors.forename: Wei-Tzu
authors.initials: WT
authors.lastname: Chen
authors.forename: Lih-Hwa
authors.initials: LH
authors.lastname: Hwang
mesh_terms: D002460:Cell Line; D050883:HSC70 Heat-Shock Proteins / Q000378:metabolism; D050884:HSP72 Heat-Shock Proteins / Q000378:metabolism*; D016174:Hepacivirus / Q000201:enzymology* / Q000378:metabolism / Q000502:physiology; D006801:Humans; D012367:RNA, Viral / Q000096:biosynthesis*; D012324:RNA-Dependent RNA Polymerase / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000378:metabolism; D014779:Virus Replication
chemical_list: D050883:HSC70 Heat-Shock Proteins; D050884:HSP72 Heat-Shock Proteins; D012367:RNA, Viral; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase