title: Destabilization of PDK1 by Hsp90 inactivation suppresses hepatitis C virus replication through inhibition of PRK2-mediated viral RNA polymerase phosphorylation.
abstract: Heat shock protein 90 (Hsp90), which chaperones multiple client proteins, has been shown to be implicated in HCV replication. Pharmacological inhibitors of Hsp90 display an anti-HCV activity. However, little is known about the mechanisms of regulation of HCV replication by Hsp90. Here, we show that Hsp90 inhibition by 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17-DMAG) destabilizes phosphoinositide-dependent kinase-1 (PDK1), an upstream kinase of the protein kinase C-related kinase 2 (PRK2) responsible for phosphorylation of HCV RNA polymerase, through the proteosome pathway. Destabilization of PDK1 led to inhibition of phosphorylation of the viral RNA polymerase through a decrease in the abundance of active form PRK2 level. Consequently, Hsp90 inhibition resulted in suppression of HCV replication both in human hepatoma Huh7 cells harboring an HCV subgenomic replicon and in HCV-infected cells. 17-DMAG treatment did not interfere with HCV internal ribosome entry site-mediated translation and the cell cycle in Huh7 cells. Co-treatment of 17-DMAG with interferon-α or HA1077, an inhibitor of PRK2, enhanced the anti-HCV activity of 17-DMAG. Taken together, these findings suggest that Hsp90 plays a critical role in the regulation of HCV RNA polymerase phosphorylation via the PDK1-PRK2 signaling pathway.
authors.affiliation: Department of Biotechnology and Translational Research Center for Protein Function Control, Yonsei University, Seoul 120-749, Republic of Korea.
authors.forename: Mi-Gyeong
authors.initials: MG
authors.lastname: Kim
authors.forename: Jae-Su
authors.initials: JS
authors.lastname: Moon
authors.forename: Eun-Jung
authors.initials: EJ
authors.lastname: Kim
authors.forename: Seung-Hoon
authors.initials: SH
authors.lastname: Lee
authors.forename: Jong-Won
authors.initials: JW
authors.lastname: Oh
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases; D016227:Benzoquinones / Q000494:pharmacology; D045744:Cell Line, Tumor; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004795:Enzyme Stability; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016174:Hepacivirus / Q000201:enzymology / Q000502:physiology*; D006801:Humans; D047029:Lactams, Macrocyclic / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D014779:Virus Replication; D012324:RNA-Dependent RNA Polymerase
chemical_list: D064413:3-Phosphoinositide-Dependent Protein Kinases; D016227:Benzoquinones; D012321:DNA-Directed RNA Polymerases; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D017361:Viral Nonstructural Proteins; C448659:17-(dimethylaminoethylamino)-17-demethoxygeldanamycin; C061570:protein kinase N; C578562:PDPK1 protein, human; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase