Peculis B A, Steitz J A
Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06536-0812.
Cell. 1993 Jun 18;73(6):1233-45. doi: 10.1016/0092-8674(93)90651-6.
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.
脊椎动物细胞的核仁含有几种小核核糖核蛋白颗粒（snRNP），其中只有一种，即U3，已被确定在核糖体RNA（rRNA）加工过程中发挥作用。我们展示了非洲爪蟾U8（一种与纤维蛋白原相关的核仁小RNA）的一级序列，并研究了其在卵母细胞发育过程中的表达情况。将反义脱氧寡核苷酸显微注射到非洲爪蟾卵母细胞中，以耗尽内源性U8 RNA库。对在U8耗尽的卵母细胞中积累的成熟rRNA和rRNA中间体的分析表明，U8 snRNP对于5.8S和28S rRNA在其5'和3'末端的正确成熟至关重要。因此，U8是一种核仁小RNA，参与了除18S成熟之外的核溶解rRNA加工步骤。本文还提供了非洲爪蟾中存在长寿命5.8S rRNA中间体（12S）的证据。
