biostudies-literatureWang MNIGMS NIH HHS1811-22https://www.ebi.ac.uk/biostudies/studies/S-EPMC3061060biostudies-literatureUnknown39(5)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 evenNucleic acids research5'-end surveillance by Xrn2 acts as a shared mechanism for mammalian pre-rRNA maturation and decay.PMC3061060R01 GM074091-06GM074091R01 GM074091Wang MPestov DGfalse5'-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 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 even2011-01-01T00:00:00Z2011 Mar2025-04-19T21:40:14.878Z2019-03-27T00:39:55ZS-EPMC30610602103687110.1093/nar/gkq1050