Biogenesis and intranuclear trafficking of human box C/D and H/ACA RNPs.
Box C/D and H/ACA snoRNAs represent two abundant groups of small noncoding RNAs. The majority of box C/D and H/ACA snoRNAs function as guide RNAs in the site-specific 2'-O-methylation and pseudouridylation of rRNAs, respectively. The box C/D snoRNAs associate with fibrillarin, Nop56, Nop58, and 15.5K/NHPX proteins to form functional snoRNP particles, whereas all box H/ACA snoRNAs form complexes with the dyskerin, Nop10, Nhp2, and Gar1 snoRNP proteins. Recent studies demonstrate that the biogenesis of mammalian snoRNPs is a complex process that requires numerous trans-acting factors. Most vertebrate snoRNAs are posttranscriptionally processed from pre-mRNA introns, and the early steps of snoRNP assembly are physically and functionally coupled with the synthesis or splicing of the host pre-mRNA. The maturing snoRNPs follow a complicated intranuclear trafficking process that is directed by transport factors also involved in nucleocytoplasmic RNA transport. The human telomerase RNA (hTR) carries a box H/ACA RNA domain that shares a common Cajal-body-specific localization element with a subclass of box H/ACA RNAs, which direct pseudouridylation of spliceosomal snRNAs in the Cajal body. However, besides concentrating in Cajal bodies, hTR also accumulates at a small, structurally distinct subset of telomeres during S phase. This suggests that a cell-cycle-dependent, dynamic localization of hTR to telomeres may play an important regulatory role in human telomere synthesis.
Kiss
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Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, IFR109, Toulouse, France.
Fayet
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Jády
B E
BE
Richard
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Weber
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M
D021581:Active Transport, Cell Nucleus; D020541:Coiled Bodies / Q000378:metabolism; D006801:Humans; D007438:Introns; D008954:Models, Biological; D009690:Nucleic Acid Conformation; D012313:RNA / Q000235:genetics / Q000378:metabolism; D012319:RNA Polymerase II / Q000378:metabolism; D012326:RNA Splicing; D020537:RNA, Small Nucleolar / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020718:Ribonucleoproteins, Small Nucleolar / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019098:Telomerase / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D058727:RNA, Small Untranslated
D020537:RNA, Small Nucleolar; D012261:Ribonucleoproteins; D020718:Ribonucleoproteins, Small Nucleolar; C422952:telomerase RNA; D012313:RNA; D012319:RNA Polymerase II; D019098:Telomerase; D058727:RNA, Small Untranslated