Centre for Biochemistry and Molecular Cell Biology, Georg-August-University, 37073 Göttingen, Germany.
Centre for Biochemistry and Molecular Cell Biology, Georg-August-University, 37073 Göttingen, Germany Göttingen Centre for Molecular Biosciences, Georg-August-University, 37073 Göttingen, Germany
RNA. 2015 Feb;21(2):180-7. doi: 10.1261/rna.047910.114. Epub 2014 Dec 18.
Ribosomal (r)RNAs are extensively modified during ribosome synthesis and their modification is required for the fidelity and efficiency of translation. Besides numerous small nucleolar RNA-guided 2'-O methylations and pseudouridinylations, a number of individual RNA methyltransferases are involved in rRNA modification. WBSCR22/Merm1, which is affected in Williams-Beuren syndrome and has been implicated in tumorigenesis and metastasis formation, was recently shown to be involved in ribosome synthesis, but its molecular functions have remained elusive. Here we show that depletion of WBSCR22 leads to nuclear accumulation of 3'-extended 18SE pre-rRNA intermediates resulting in impaired 18S rRNA maturation. We map the 3' ends of the 18SE pre-rRNA intermediates accumulating after depletion of WBSCR22 and in control cells using 3'-RACE and deep sequencing. Furthermore, we demonstrate that WBSCR22 is required for N(7)-methylation of G1639 in human 18S rRNA in vivo. Interestingly, the catalytic activity of WBSCR22 is not required for 18S pre-rRNA processing, suggesting that the key role of WBSCR22 in 40S subunit biogenesis is independent of its function as an RNA methyltransferase.
核糖体 (r)RNA 在核糖体合成过程中会受到广泛修饰，其修饰对于翻译的准确性和效率至关重要。除了大量的小核仁 RNA 指导的 2'-O 甲基化和假尿嘧啶化之外，许多个别 RNA 甲基转移酶也参与了 rRNA 修饰。WBSCR22/Merm1 是威廉姆斯-贝伦综合征的致病基因，并且与肿瘤发生和转移形成有关，最近被证明参与核糖体合成，但它的分子功能仍然难以捉摸。在这里，我们表明 WBSCR22 的耗竭会导致 3'-延伸的 18SE 前 rRNA 中间体在核内积累，从而导致 18S rRNA 成熟受损。我们使用 3'-RACE 和深度测序来映射 WBSCR22 耗尽后和对照细胞中积累的 18SE 前 rRNA 中间体的 3' 末端。此外，我们证明 WBSCR22 是体内人 18S rRNA 中 G1639 的 N(7)-甲基化所必需的。有趣的是，WBSCR22 的催化活性对于 18S 前 rRNA 加工不是必需的，这表明 WBSCR22 在 40S 亚基生物发生中的关键作用与其作为 RNA 甲基转移酶的功能无关。
