title: Molecular determinants of nucleolar translocation of RNA helicase A.
abstract: RNA helicase A (RHA) is a member of the DEAH-box family of DNA/RNA helicases involved in multiple cellular processes and the life cycles of many viruses. The subcellular localization of RHA is dynamic despite its steady-state concentration in the nucleoplasm. We have previously shown that it shuttles rapidly between the nucleus and the cytoplasm by virtue of a bidirectional nuclear transport domain (NTD) located in its carboxyl terminus. Here, we investigate the molecular determinants for its translocation within the nucleus and, more specifically, its redistribution from the nucleoplasm to nucleolus or the perinucleolar region. We found that low temperature treatment, transcription inhibition or replication of hepatitis C virus caused the intranuclear redistribution of the protein, suggesting that RHA shuttles between the nucleolus and nucleoplasm and becomes trapped in the nucleolus or the perinucleolar region upon blockade of transport to the nucleoplasm. Both the NTD and ATPase activity were essential for RHA's transport to the nucleolus or perinucleolar region. One of the double-stranded RNA binding domains (dsRBD II) was also required for this nucleolar translocation (NoT) phenotype. RNA interference studies revealed that RHA is essential for survival of cultured hepatoma cells and the ATPase activity appears to be important for this critical role.
authors.affiliation: Department of Biological Science, Florida State University, Tallahassee, FL 32306-4370, USA.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Liu
authors.forename: Rachael
authors.initials: R
authors.lastname: Kenworthy
authors.forename: Christopher
authors.initials: C
authors.lastname: Green
authors.forename: Hengli
authors.initials: H
authors.lastname: Tang
mesh_terms: D021581:Active Transport, Cell Nucleus; D000251:Adenosine Triphosphatases / Q000378:metabolism; D020816:Amino Acid Motifs; D000818:Animals; D017209:Apoptosis; D045744:Cell Line, Tumor; D002466:Cell Nucleolus / Q000201:enzymology*; D004004:Dichlororibofuranosylbenzimidazole / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016174:Hepacivirus / Q000502:physiology*; D006801:Humans; D051379:Mice; D019913:Nuclear Localization Signals / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D020365:RNA Helicases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014779:Virus Replication