Dunbar D A, Baserga S J
Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut 06520-8040, USA.
RNA. 1998 Feb;4(2):195-204.
We have studied the role of the U14 small nucleolar RNA (snoRNA) in pre-rRNA methylation and processing in Xenopus oocytes. Depletion of U14 in Xenopus oocytes was achieved by co-injecting two nonoverlapping antisense oligonucleotides. Focusing on the earliest precursor, depletion experiments revealed that the U14 snoRNA is essential for 2'-O-ribose methylation at nt 427 of the 18S rRNA. Injection of U14-depleted oocytes with specific U14 mutant snoRNAs indicated that conserved domain B, but not domain A, of U14 is required for the methylation reaction. When the effect of U14 on pre-rRNA processing is assayed, we find only modest effects on 18S rRNA levels, and no effect on the type or accumulation of 18S precursors, suggesting a role for U14 in a step in ribosome biogenesis other than cleavage of the pre-rRNA. Xenopus U14 is, therefore, a Box C/D fibrillarin-associated snoRNA that is required for site-specific 2'-O-ribose methylation of pre-rRNA.
我们研究了U14小核仁RNA（snoRNA）在非洲爪蟾卵母细胞前体rRNA甲基化和加工过程中的作用。通过共注射两种不重叠的反义寡核苷酸实现了非洲爪蟾卵母细胞中U14的缺失。聚焦于最早的前体，缺失实验表明U14 snoRNA对于18S rRNA第427位核苷酸的2'-O-核糖甲基化至关重要。向U14缺失的卵母细胞注射特定的U14突变snoRNA表明，U14的保守结构域B而非结构域A是甲基化反应所必需的。当检测U14对前体rRNA加工的影响时，我们发现其对18S rRNA水平仅有适度影响，对18S前体的类型或积累没有影响，这表明U14在核糖体生物发生过程中除前体rRNA切割之外的一个步骤中发挥作用。因此，非洲爪蟾U14是一种与C/D盒纤维蛋白相关的snoRNA，是前体rRNA位点特异性2'-O-核糖甲基化所必需的。
