title: Three small nucleolar RNAs that are involved in ribosomal RNA precursor processing.
abstract: Three small nucleolar RNAs (snoRNAs), E1, E2 and E3, have been described that have unique sequences and interact directly with unique segments of pre-rRNA in vivo. In this report, injection of antisense oligodeoxynucleotides into Xenopus laevis oocytes was used to target the specific degradation of these snoRNAs. Specific disruptions of pre-rRNA processing were then observed, which were reversed by injection of the corresponding in vitro-synthesized snoRNA. Degradation of each of these three snoRNAs produced a unique rRNA maturation phenotype. E1 RNA depletion shut down 18 rRNA formation, without overaccumulation of 20S pre-rRNA. After E2 RNA degradation, production of 18S rRNA and 36S pre-rRNA stopped, and 38S pre-rRNA accumulated, without overaccumulation of 20S pre-rRNA. E3 RNA depletion induced the accumulation of 36S pre-rRNA. This suggests that each of these snoRNAs plays a different role in pre-rRNA processing and indicates that E1 and E2 RNAs are essential for 18S rRNA formation. The available data support the proposal that these snoRNAs are at least involved in pre-rRNA processing at the following pre-rRNA cleavage sites: E1 at the 5' end and E2 at the 3' end of 18S rRNA, and E3 at or near the 5' end of 5.8S rRNA.
authors.affiliation: Department of Pathology, Saint Louis University School of Medicine, St. Louis, MO 63104-1028, USA.
authors.forename: R K
authors.initials: RK
authors.lastname: Mishra
authors.forename: G L
authors.initials: GL
authors.lastname: Eliceiri
mesh_terms: D000818:Animals; D001483:Base Sequence; D002466:Cell Nucleolus / Q000378:metabolism; D016384:Consensus Sequence; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D016376:Oligonucleotides, Antisense; D009865:Oocytes / Q000378:metabolism; D012322:RNA Precursors / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D012342:RNA, Small Nuclear / Q000737:chemistry / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D014714:Vertebrates; D014982:Xenopus laevis
chemical_list: D016376:Oligonucleotides, Antisense; D012322:RNA Precursors; D012335:RNA, Ribosomal; D012342:RNA, Small Nuclear