5'-end surveillance by Xrn2 acts as a shared mechanism for mammalian pre-rRNA maturation and decay

Ribosome biogenesis requires multiple nuclease activities to process pre-rRNA transcripts into mature rRNA species and eliminate defective products of transcription and processing. We find that in mammalian cells, the 5' exonuclease Xrn2 plays a major role in both maturation of rRNA and degrada...

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Bibliographic Details
Published in:Nucleic acids research 2011-03, Vol.39 (5), p.1811-1822
Main Authors: Wang, Minshi, Pestov, Dimitri G
Format: Article
Language:English
Subjects:
Animals
Exoribonucleases - antagonists & inhibitors
Exoribonucleases - physiology
Mice
NIH 3T3 Cells
Nuclear Proteins - physiology
RNA
RNA Precursors - metabolism
RNA Processing, Post-Transcriptional
RNA Stability
RNA, Ribosomal - metabolism
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Summary:Ribosome biogenesis requires multiple nuclease activities to process pre-rRNA transcripts into mature rRNA species and eliminate defective products of transcription and processing. We find that in mammalian cells, the 5' exonuclease Xrn2 plays a major role in both maturation of rRNA and degradation of a variety of discarded pre-rRNA species. Precursors of 5.8S and 28S rRNAs containing 5' extensions accumulate in mouse cells after siRNA-mediated knockdown of Xrn2, indicating similarity in the 5'-end maturation mechanisms between mammals and yeast. Strikingly, degradation of many aberrant pre-rRNA species, attributed mainly to 3' exonucleases in yeast studies, occurs 5' to 3' in mammalian cells and is mediated by Xrn2. Furthermore, depletion of Xrn2 reveals pre-rRNAs derived by cleavage events that deviate from the main processing pathway. We propose that probing of pre-rRNA maturation intermediates by exonucleases serves the dual function of generating mature rRNAs and suppressing suboptimal processing paths during ribosome assembly.
ISSN:0305-1048
1362-4962
DOI:10.1093/nar/gkq1050