WDR74 participates in an early cleavage of the pre-rRNA processing pathway in cooperation with the nucleolar AAA-ATPase NVL2
WDR74 participates in an early cleavage of the pre-rRNA processing pathway in cooperation with the nucleolar AAA-ATPase NVL2
复制标题
DOI：
10.1016/j.bbrc.2017.10.148
复制
发表时间：
2018-01-01
影响因子：
3.1
通讯作者：
Nagahama, Masami
中科院分区：
文献类型：
--
作者：
Hiraishi, Nobuhiro;Ishida, Yo-ichi;Nagahama, Masami
WD重复蛋白74(WDR74)是一种核仁定位蛋白，是酵母中一种60S核糖体组装因子Nsa1的哺乳动物同源基因。我们先前发现WDR74与核外切体辅助RNA解旋酶MTR4相关，其解离被AAA型伴侣NVL2的ATPase缺陷突变体阻止。然而，WDR74在与NVL2协同的核糖体生物发生过程中的功能和调控仍不清楚。在这里，我们证明了WDR74的敲除导致了内部转录间隔区1(ITS1)内的前rRNA裂解的显著缺陷，发生在加工途径的早期阶段。有趣的是，当突变的NVL2表达时，WDR74从含有MTR4的核酸外切酶复合体上的解离受到损害，同样的加工缺陷也被观察到，WDR74从核仁向核质部分迁移。在核质中，原位邻近连接实验检测到WDR74与MTR4之间的相互作用增强。因此，在rRNA合成的后期，WDR74与MTR4的解离被认为是60年代前颗粒适当成熟所必需的。这些结果表明，核糖体生物发生的时空调节是由NVL2的ATPase活性介导的。(C)2017 Elsevier Inc.保留所有权利。
WD repeat-containing protein 74 (WDR74), a nucleolar-localized protein, is the mammalian ortholog of Nsa1, a 60S ribosome assembly factor in yeast. We previously showed that WDR74 associates with MTR4, the nuclear exosome-assisting RNA helicase, whose dissociation is prohibited by an ATPase-deficient mutant of the AAA-type chaperone NVL2. However, the functions and regulation of WDR74 during ribosome biogenesis in cooperation with NVL2 remains unknown. Here, we demonstrated that knockdown of WDR74 leads to significant defects in the pre-rRNA cleavage within the internal transcribed spacer 1 (ITS1), occurring in an early stage of the processing pathway. Interestingly, when the dissociation of WDR74 from the MTR4-containing exonuclease complex was impaired upon expression of the mutant NVL2, the same processing defect, with partial migration of WDR74 from the nucleolus towards the nucleoplasm, was observed. In the nucleoplasm, an increased interaction between WDR74 and MTR4 was detected by in situ proximity ligation assay. Therefore, the dissociation of WDR74 from MTR4 in a late stage of rRNA synthesis is thought to be required for appropriate maturation of the pre-60S particles. These results suggest that the spatiotemporal regulation of ribosome biogenesis in the nucleolus is mediated by the ATPase activity of NVL2. (C) 2017 Elsevier Inc. All rights reserved.