Mammalian and yeast U3 snoRNPs are matured in specific and related nuclear compartments
Mammalian and yeast U3 snoRNPs are matured in specific and related nuclear compartments
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DOI：
10.1093/emboj/21.11.2736
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发表时间：
2002-06-03
期刊：
影响因子：
11.4
通讯作者：
Bertrand, E
中科院分区：
文献类型：
--
作者：
Verheggen, C;Lafontaine, DLJ;Bertrand, E
脊椎动物box C/D snoRNA的核仁定位涉及通过Cajal小体，但这一事件的意义尚不清楚。为了更好地确定这个隔室的功能，我们在这里分析了哺乳动物U3的成熟途径。我们发现，3‘-延伸的U3前体具有单甲基化的帽子，与纤维蛋白和hNop58无关。重要的是，这些前体在它们的转录位点和Cajal小体中都被检测到。此外，成熟的U3、核心盒C/D蛋白和人类负责U3帽三甲基化的甲基转移酶hTgs1都存在于Cajal小体中。在酵母中，U3遵循类似的成熟途径，相当于3‘-延伸的前体富含在核仁和核仁体中，核仁体是一个在特定生长条件下浓缩Tgs1p的核仁域。因此，U3成熟的空间组织似乎在进化过程中是保守的，并涉及专门的和相关的核室，酵母中的核仁/核仁体和高等真核生物中的Cajal小体。这些可能是snoRNP组装、3‘端成熟和帽修饰的场所。
Nucleolar localization of vertebrate box C/D snoRNA involves transit through Cajal bodies, but the significance of this event is unkown. To define better the function of this compartment, we analyzed here the maturation pathway of mammalian U3. We show that 3'-extended U3 precursors possess a mono-methylated cap, and are not associated with fibrillarin and hNop58. Importantly, these precursors are detected at both their transcription sites and in Cajal bodies. In addition, mature U3, the core box C/D proteins and the human homolog of the methyltransferase responsible for U3 cap tri-methylation, hTgs1, are all present in Cajal bodies. In yeast, U3 follows a similar maturation pathway, and equivalent 3'-extended precursors are enriched in the nucleolus and in the nucleolar body, a nucleolar domain that concentrates Tgs1p under certain growth conditions. Thus, spatial organization of U3 maturation appears to be conserved across evolution, and involves specialized and related nuclear compartments, the nucleolus/nucleolar body in yeast and Cajal bodies in higher eukaryotes. These are likely places for snoRNP assembly, 3' end maturation and cap modification.