Disruption of U8 nucleolar snRNA inhibits 5.8S and 28S rRNA processing in the Xenopus oocyte.
The nucleoli of vertebrate cells contain several snRNPs, of which only one, U3, has been assigned a role in rRNA processing. We present the primary sequence of Xenopus U8, a fibrillarin-associated nucleolar snRNA, and examine its expression through oocyte development. Antisense deoxyoligonucleotides were microinjected into Xenopus oocytes to deplete the endogenous pool of U8 RNA. Analysis of the mature rRNAs and rRNA intermediates that accumulate in the U8-depleted oocytes indicate that the U8 snRNP is essential for correct maturation of the 5.8S and 28S rRNAs at both their 5' and 3' ends. U8 is therefore a nucleolar snRNA implicated in a nucleolytic rRNA processing step other than 18S maturation. Evidence for a long-lived 5.8S rRNA intermediate (12S) in Xenopus is also presented.
Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06536-0812.
B A
BA
Peculis
J A
JA
Steitz
D000818:Animals; D001483:Base Sequence; D016373:DNA, Antisense / Q000494:pharmacology; D005260:Female; D006801:Humans; D008969:Molecular Sequence Data; D009865:Oocytes; D012339:RNA, Ribosomal, 28S / Q000187:drug effects*; D012340:RNA, Ribosomal, 5.8S / Q000187:drug effects*; D012342:RNA, Small Nuclear; D017414:Ribonucleoprotein, U4-U6 Small Nuclear / Q000502:physiology*; D014981:Xenopus
D016373:DNA, Antisense; D012339:RNA, Ribosomal, 28S; D012340:RNA, Ribosomal, 5.8S; D012342:RNA, Small Nuclear; D017414:Ribonucleoprotein, U4-U6 Small Nuclear