title: The alpha isoform of protein kinase CKI is responsible for hepatitis C virus NS5A hyperphosphorylation.
abstract: Hepatitis C virus (HCV) has been the subject of intensive studies for nearly two decades. Nevertheless, some aspects of the virus life cycle are still a mystery. The HCV nonstructural protein 5A (NS5A) has been shown to be a modulator of cellular processes possibly required for the establishment of viral persistence. NS5A is heavily phosphorylated, and a switch between a basally phosphorylated form of NS5A (p56) and a hyperphosphorylated form of NS5A (p58) seems to play a pivotal role in regulating HCV replication. Using kinase inhibitors that specifically inhibit the formation of NS5A-p58 in cells, we identified the CKI kinase family as a target. NS5A-p58 increased upon overexpression of CKI-alpha, CKI-delta, and CKI-epsilon, whereas the RNA interference of only CKI-alpha reduced NS5A hyperphosphorylation. Rescue of inhibition of NS5A-p58 was achieved by CKI-alpha overexpression, and we demonstrated that the CKI-alpha isoform is targeted by NS5A hyperphosphorylation inhibitors in living cells. Finally, we showed that down-regulation of CKI-alpha attenuates HCV RNA replication.
authors.affiliation: Istituto di Ricerche di Biologia Molecolare "P. Angeletti," 00040 Pomezia (Roma), Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Quintavalle
authors.forename: Sonia
authors.initials: S
authors.lastname: Sambucini
authors.forename: Chiara
authors.initials: C
authors.lastname: Di Pietro
authors.forename: Raffaele
authors.initials: R
authors.lastname: De Francesco
authors.forename: Petra
authors.initials: P
authors.lastname: Neddermann
mesh_terms: D048149:Casein Kinase 1 epsilon / Q000235:genetics / Q000378:metabolism; D048128:Casein Kinase Ialpha / Q000235:genetics / Q000378:metabolism*; D048148:Casein Kinase Idelta / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D024202:Electrophoretic Mobility Shift Assay; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016174:Hepacivirus / Q000502:physiology*; D006801:Humans; D010766:Phosphorylation; D034622:RNA Interference; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D048149:Casein Kinase 1 epsilon; D048128:Casein Kinase Ialpha; D048148:Casein Kinase Idelta; D004791:Enzyme Inhibitors; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase