title: The 5' external transcribed spacer in mouse ribosomal RNA contains two cleavage sites.
abstract: The 5' external transcribed spacer (5'ETS) is critical for 18S rRNA formation and is the longest noncoding region in a ribosomal RNA transcript. Here we show that processing in mouse 5'ETS involves two cleavage events. Processing at site A' corresponds to the previously described "primary cleavage," which precedes other processing steps. Processing at the novel site A0 occurs 1 kb downstream from A' yielding two new rRNA precursors: 43S and 29S. The excised 5'-A' and A'-A0 fragments are rapidly degraded under normal conditions. Depletion of the exosome component EXOSC10/PM-Scl100 (ortholog of yeast Rrp6p) results in a strong accumulation of the A'-A0 spacer fragment in mouse cells. We discuss the finding of a second processing site in mammalian 5'ETS in relation to the involvement of the U3 snoRNA in pre-rRNA processing and present a revised map of the mouse 18S rRNA processing pathway.
authors.affiliation: Department of Cell Biology, School of Osteopathic Medicine, University of Medicine and Dentistry of New Jersey, Stratford, New Jersey 08084, USA.
authors.forename: Tatyana
authors.initials: T
authors.lastname: Kent
authors.forename: Yevgeniya R
authors.initials: YR
authors.lastname: Lapik
authors.forename: Dimitri G
authors.initials: DG
authors.lastname: Pestov
mesh_terms: D000818:Animals; D021903:DNA, Ribosomal Spacer / Q000737:chemistry*; D005095:Exoribonucleases / Q000737:chemistry / Q000378:metabolism; D063326:Exosome Multienzyme Ribonuclease Complex; D055354:Exosomes / Q000378:metabolism; D006801:Humans; D051379:Mice; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D012322:RNA Precursors / Q000737:chemistry / Q000378:metabolism; D012326:RNA Splicing / Q000502:physiology; D012335:RNA, Ribosomal / Q000737:chemistry* / Q000378:metabolism; D012337:RNA, Ribosomal, 18S / Q000737:chemistry / Q000378:metabolism; D020537:RNA, Small Nucleolar / Q000378:metabolism; D022661:RNA, Untranslated / Q000737:chemistry / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D021903:DNA, Ribosomal Spacer; D012322:RNA Precursors; D012335:RNA, Ribosomal; D012337:RNA, Ribosomal, 18S; D020537:RNA, Small Nucleolar; C117378:RNA, U3 small nucleolar; D022661:RNA, Untranslated; D029701:Saccharomyces cerevisiae Proteins; D005095:Exoribonucleases; D063326:Exosome Multienzyme Ribonuclease Complex; C112610:RRP6 protein, S cerevisiae