title: Transcription-dependent nucleolar cap localization and possible nuclear function of DExH RNA helicase RHAU.
abstract: RHAU (RNA helicase associated with AU-rich element) is a DExH protein originally identified as a factor accelerating AU-rich element-mediated mRNA degradation. The discovery that RHAU is predominantly localized in the nucleus, despite mRNA degradation occurring in the cytoplasm, prompted us to consider the nuclear functions of RHAU. In HeLa cells, RHAU was found to be localized throughout the nucleoplasm with some concentrated in nuclear speckles. Transcriptional arrest altered the localization to nucleolar caps, where RHAU is closely localized with RNA helicases p68 and p72, suggesting that RHAU is involved in transcription-related RNA metabolism in the nucleus. To see whether RHAU affects global gene expression transcriptionally or posttranscriptionally, we performed microarray analysis using total RNA from RHAU-depleted HeLa cell lines, measuring both steady-state mRNA levels and mRNA half-lives by actinomycin D chase. There was no change in the half-lives of most transcripts whose steady-state levels were affected by RHAU knockdown, suggesting that these transcripts are subjected to transcriptional regulation. We propose that RHAU has a dual function, being involved in both the synthesis and degradation of mRNA in different subcellular compartments.
authors.affiliation: Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, Basel, Switzerland.
authors.forename: Fumiko
authors.initials: F
authors.lastname: Iwamoto
authors.forename: Michael
authors.initials: M
authors.lastname: Stadler
authors.forename: Katerina
authors.initials: K
authors.lastname: Chalupníková
authors.forename: Edward
authors.initials: E
authors.lastname: Oakeley
authors.forename: Yoshikuni
authors.initials: Y
authors.lastname: Nagamine
mesh_terms: D002466:Cell Nucleolus / Q000201:enzymology*; D053487:DEAD-box RNA Helicases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006207:Half-Life; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D050505:Mutant Proteins / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D011485:Protein Binding; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D050505:Mutant Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C466988:DHX36 protein, human; D053487:DEAD-box RNA Helicases