The homologous putative GTPases grn1p from fission yeast and the human GNL3L are required for growth and play a role in processing of nucleolar Pre-rRNA
The homologous putative GTPases grn1p from fission yeast and the human GNL3L are required for growth and play a role in processing of nucleolar Pre-rRNA
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DOI：
10.1091/mbc.e05-09-0848
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发表时间：
2006-01-01
影响因子：
3.3
通讯作者：
Balasundaram, D
中科院分区：
文献类型：
--
作者：
Du, XM;Rao, MRKS;Balasundaram, D
来自裂殖酵母的Grn 1 p和来自人类细胞的GNL 3L，来自具有环状排列的G基序的新型HSR1_MMR1 GTP结合蛋白亚家族的两种推定的GTP酶在维持正常细胞生长中起关键作用。Grn 1的缺失导致了严重的生长缺陷，伴随着35 S前rRNA转录物的积累，成熟rRNA种类显著减少，并且未能从核仁输出核糖体蛋白Rp 125 a。删除任何Grn 1 p G-结构域基序导致无效表型和核/核仁定位与伴随核仁结构扭曲的前核糖体核仁出口缺乏一致。在Delta grn 1突变体中GNL 3L的异源表达恢复了35 S前rRNA的加工、Rp 125 a的核输出和细胞生长至野生型水平。酵母中的遗传互补和HeLa细胞中的siRNA敲低证实了同源蛋白Grn 1 p和GNL 3L是生长所需的。两个类似的HSR1_MMR1推定的核仁GTP酶，核干细胞蛋白（NS），或乳腺肿瘤自身抗原NGP-1的剂量依赖性反应，以拯救Delta grn 1的失败意味着Grn 1 p或GNL 3L在核仁事件中的高度特异性作用。我们的分析揭示了Grn 1 p/GNL 3L在这组独特的核仁GTP酶中的重要作用。
Grn1p from fission yeast and GNL3L from human cells, two putative GTPases from the novel HSR1_MMR1 GTP-binding protein subfamily with circularly permuted G-motifs play a critical role in maintaining normal cell growth. Deletion of Grn1 resulted in a severe growth defect, a marked reduction in mature rRNA species with a concomitant accumulation of the 35S pre-rRNA transcript, and failure to export the ribosomal protein Rp125a from the nucleolus. Deleting any of the Grn1p G-domain motifs resulted in a null phenotype and nuclear/nucleolar localization consistent with the lack of nucleolar export of preribosomes accompanied by a distortion of nucleolar structure. Heterologous expression of GNL3L in a Delta grn1 mutant restored processing of 35S pre-rRNA, nuclear export of Rp125a and cell growth to wild-type levels. Genetic complementation in yeast and siRNA knockdown in HeLa cells confirmed the homologous proteins Grn1p and GNL3L are required for growth. Failure of two similar HSR1_MMR1 putative nucleolar GTPases, Nucleostemin (NS), or the dose-dependent response of breast tumor autoantigen NGP-1, to rescue Delta grn1 implied the highly specific roles of Grn1p or GNL3L in nucleolar events. Our analysis uncovers an important role for Grn1p/GNL3L within this unique group of nucleolar GTPases.