A nuclear envelope protein linking nuclear pore basket assembly, SUMO protease regulation, and mRNA surveillance
A nuclear envelope protein linking nuclear pore basket assembly, SUMO protease regulation, and mRNA surveillance
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DOI：
10.1083/jcb.200702154
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发表时间：
2007-08-27
影响因子：
7.8
通讯作者：
Hochstrasser, Mark
中科院分区：
文献类型：
--
作者：
Lewis, Alaron;Felberbaum, Rachael;Hochstrasser, Mark
核孔复合物（NPC）既是核质运输的主要通道，也是核膜上组织大分子的平台。我们报告说，酵母Esc1，非NPC核膜蛋白，是必要的核篮，从NPC延伸到细胞核的结构，并为正常的NPC本地化的Ulp1 SUMO蛋白酶的正确组装。在esc1 Delta细胞中，Ulp 1和核篮组分Nup60和Mlp 1不再广泛分布在核周围，而是共定位于少量的染色密集的核周灶中。Esc1（或Nup60）的缺失改变SUMO缀合物积累并增强ulp1突变缺陷。与先前对Mlp1的发现类似，Esc 1和Ulp1都有助于将未剪接的前mRNA保留在细胞核中。因此，这些蛋白质对于适当的核篮功能是必不可少的，包括mRNA监视和SUMO蛋白动力学的调节。这些结果提出了一种可能性，即NPC定位的蛋白质去小泛素化可能是防止不适当的前体mRNA输出的关键调控事件。
The nuclear pore complex (NPC) is both the major conduit for nucleocytoplasmic trafficking and a platform for organizing macromolecules at the nuclear envelope. We report that yeast Esc1, a non-NPC nuclear envelope protein, is required both for proper assembly of the nuclear basket, a structure extending into the nucleus from the NPC, and for normal NPC localization of the Ulp1 SUMO protease. In esc1 Delta cells, Ulp1 and nuclear basket components Nup60 and Mlp1 no longer distribute broadly around the nuclear periphery, but co-localize in a small number of dense-staining perinuclear foci. Loss of Esc1 (or Nup60) alters SUMO conjugate accumulation and enhances ulp1 mutant defects. Similar to previous findings with Mlp1, both Esc1 and Ulp1 help retain un-spliced pre-mRNAs in the nucleus. Therefore, these proteins are essential for proper nuclear basket function, which includes mRNA surveillance and regulation of SUMO protein dynamics. The results raise the possibility that NPC-localized protein desumoylation may be a key regulatory event preventing inappropriate premRNA export.