Nuclear-localized Asunder regulates cytoplasmic dynein localization via its role in the Integrator complex
Nuclear-localized Asunder regulates cytoplasmic dynein localization via its role in the Integrator complex
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DOI：
10.1091/mbc.e13-05-0254
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发表时间：
2013-09-15
影响因子：
3.3
通讯作者：
Lee, Laura A.
中科院分区：
文献类型：
--
作者：
Jodoin, Jeanne N.;Sitaram, Poojitha;Lee, Laura A.
我们以前报道过，在培养的人类细胞和果蝇精母细胞中，asUnder(ASun)对于动力蛋白马达在细胞分裂开始时募集到核膜(NE)和核-中心体耦合是必不可少的，尽管这一调控的机制尚不清楚。我们还发现ASUN是整合子(INT)的功能成分，整合子是小核RNA 3‘端处理所需的多亚单位复合体。我们现在提供的证据表明，ASun在核内与其他INT成分协同作用，调节强力素向NE的募集。HeLa细胞中其他个别INT亚基的敲除重现了ASun-Small干扰RNA细胞中核周动力蛋白的丢失。ASUN通过核定位序列的突变被强制定位到细胞质中，阻止了其在缺乏ASUN的培养细胞和果蝇ASUN精母细胞中恢复核周动力蛋白的能力。此外，当Dynein被招募到NE时，几个INT亚基的水平在G2/M时降低，这表明INT不直接介导这一步骤。综上所述，我们的数据支持一个模型，在该模型中，核INT复合体可能通过一种涉及RNA加工的机制促进细胞质动力蛋白向NE的募集。
We previously reported that Asunder (ASUN) is essential for recruitment of dynein motors to the nuclear envelope (NE) and nucleus-centrosome coupling at the onset of cell division in cultured human cells and Drosophila spermatocytes, although the mechanisms underlying this regulation remain unknown. We also identified ASUN as a functional component of Integrator (INT), a multisubunit complex required for 3'-end processing of small nuclear RNAs. We now provide evidence that ASUN acts in the nucleus in concert with other INT components to mediate recruitment of dynein to the NE. Knockdown of other individual INT subunits in HeLa cells recapitulates the loss of perinuclear dynein in ASUN-small interfering RNA cells. Forced localization of ASUN to the cytoplasm via mutation of its nuclear localization sequence blocks its capacity to restore perinuclear dynein in both cultured human cells lacking ASUN and Drosophila asun spermatocytes. In addition, the levels of several INT subunits are reduced at G2/M when dynein is recruited to the NE, suggesting that INT does not directly mediate this step. Taken together, our data support a model in which a nuclear INT complex promotes recruitment of cytoplasmic dynein to the NE, possibly via a mechanism involving RNA processing.