Cotranscriptional recognition of human intronic box H/ACA snoRNAs occurs in a splicing-independent manner.
Processing from pre-mRNA introns is a widespread mechanism to generate human box C/D and H/ACA snoRNAs. Recent studies revealed that an optimal position relative to the 3' splice site is important for efficient processing of most box C/D snoRNAs and that assembly of box C/D snoRNPs is stimulated by splicing factors likely bound to the branch point region. Here we have investigated the processing of another major class of human intron-encoded RNAs, the box H/ACA snoRNAs. Analysis of 80 H/ACA RNA genes revealed that human H/ACA RNAs possess no preferential localization close to the 3' or 5' splice site. In vivo processing experiments confirmed that H/ACA intronic snoRNAs are processed in a position-independent manner, indicating that there is no synergy between H/ACA RNA processing and splicing. We also showed that recognition of intronic H/ACA snoRNAs and assembly of pre-snoRNPs is an early event that occurs during transcription elongation parallel with pre-mRNA splice site selection. Finally, we found that efficient processing and correct nucleolar localization of the human U64 H/ACA snoRNA requires RNA polymerase II-mediated synthesis of the U64 precursor. This suggests that polymerase II-associated factors direct the efficient assembly and determine the correct subnuclear trafficking of human H/ACA snoRNPs.
Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, IFR109, 118 route de Narbonne, 31062 Toulouse, France.
Patricia
P
Richard
Arnold M
AM
Kiss
Xavier
X
Darzacq
Tamás
T
Kiss
D018797:Cell Cycle Proteins / Q000378:metabolism; D004257:DNA Polymerase II / Q000378:metabolism; D021901:DNA, Intergenic / Q000235:genetics; D005914:Globins / Q000235:genetics; D006801:Humans; D007438:Introns / Q000235:genetics*; D009687:Nuclear Proteins / Q000378:metabolism; D012322:RNA Precursors / Q000235:genetics; D012323:RNA Processing, Post-Transcriptional / Q000235:genetics; D022821:RNA Splice Sites / Q000235:genetics; D012326:RNA Splicing / Q000235:genetics; D020537:RNA, Small Nucleolar / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics*
D018797:Cell Cycle Proteins; C112148:DKC1 protein, human; D021901:DNA, Intergenic; D009687:Nuclear Proteins; D012322:RNA Precursors; D022821:RNA Splice Sites; D020537:RNA, Small Nucleolar; D016601:RNA-Binding Proteins; D005914:Globins; D004257:DNA Polymerase II