Nuclear RanGTP is not required for targeting small nucleolar RNAs to the nucleolus

被引:19
作者
Narayanan, A
Eifert, J
Marfatia, KA
Macara, IG
Corbett, AH
Terns, RM
Terns, MP
机构
[1] Univ Georgia, Dept Biochem & Mol Biol, Athens, GA 30602 USA
[2] Univ Georgia, Dept Genet, Athens, GA 30602 USA
[3] Emory Univ, Dept Biochem, Atlanta, GA 30322 USA
[4] Univ Virginia, Sch Med, Ctr Cell Signaling, Dept Pharmacol, Charlottesville, VA 22908 USA
关键词
small nucleolar RNA; RanGTP; RNA transport; nucleolus; tsBN2; Xenopus oocytes; S; cerevisiae;
D O I
10.1242/jcs.00176
中图分类号
Q2 [细胞生物学];
学科分类号
071009 ; 090102 ;
摘要
The small GTPase Ran is the central regulator of macromolecular transport between the cytoplasm and the nucleus. Recent work has suggested that RanGTP also plays an important role in regulating some intra-nuclear processes. In this study, we have investigated whether RanGTP is required for the intra-nuclear transport of RNAs. Specifically, we directly analyzed the nucleolar localization of Box C/D and Box H/ACA small nucleolar RNAs (snoRNAs) in mammalian (tsBN2) cells, Saccharomyces cerevisiae and Xenopus oocytes under conditions that deplete nuclear RanGTP and prevent RNA export to the cytoplasm. Our data suggest that depletion of nuclear RanGTP does not significantly alter the nucleolar localization of U3 snoRNA in tsBN2 cells. Complementary studies in the budding yeast S. cerevisiae using conditional Ran mutants as well as mutants in Ran regulatory proteins also indicate that disruption of the Ran gradient or of Ran itself does not detectably affect the nucleolar localization of snoRNAs. Finally, microinjection into Xenopus oocytes was used to clearly demonstrate that a specific pool of snoRNAs could still be efficiently targeted to the nucleolus even when the RanGTP gradient was disrupted by microinjection of mutant Ran proteins. Taken together, our data from three phylogenetically distinct experimental systems suggest that nuclear RanGTP, which is essential for trafficking of RNAs between the nuclear and cytoplasmic compartments, is not required for nuclear retention or nucleolar localization of snoRNAs.
引用
收藏
页码:177 / 186
页数:10
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