Abundance of the largest subunit of RNA polymerase II in the nucleus is regulated by nucleo-cytoplasmic shuttling
Abundance of the largest subunit of RNA polymerase II in the nucleus is regulated by nucleo-cytoplasmic shuttling
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DOI：
10.1016/j.yexcr.2006.04.018
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发表时间：
2006-08-01
影响因子：
3.7
通讯作者：
Carmo-Fonseca, Maria
中科院分区：
文献类型：
--
作者：
Custodio, Noelia;Antoniou, Michael;Carmo-Fonseca, Maria
真核RNA聚合酶II是一种由12个不同亚基组成的复合酶，存在于低丰度的细胞中。RNA聚合酶11对mRNA的转录涉及酶最大亚基的羧基末端结构域(CTD)的磷酸化/去磷酸化循环。我们已经建立了稳定的小鼠细胞系，表达RNA聚合酶II的最大亚单位(RNA Pol II LS)的U-Amanitin抗性形式。这些细胞在ET-Amanitin存在的情况下保持转录活性，表明外源蛋白具有功能。我们观察到过表达的RNA Pol II LS主要是低磷酸化的，可溶的，并以CRM1依赖的方式积聚在细胞质中。我们的结果进一步表明，转录活性形式的RNA Pol II LS在CTD重复序列的第2位含有磷酸丝氨酸，限制在细胞核内，其水平保持显著稳定。我们认为，RNA Pol II LS的核质穿梭可能提供了一种机制来控制RNA聚合酶亚基的池，该池可用于在核中组装功能酶。(C)2006 Elsevier Inc.保留所有权利。
Eukaryotic RNA polymerase II is a complex enzyme composed of 12 distinct subunits that is present in cells in low abundance. Transcription of mRNA by RNA polymerase 11 involves a phosphorylation/dephosphorylation cycle of the carboxyl-terminal domain (CTD) of the enzyme's largest subunit. We have generated stable murine cell lines expressing an U-amanitin-resistant form of the largest subunit of RNA polymerase II (RNA Pol II LS). These cells maintained transcriptional activity in the presence of et-amanitin, indicating that the exogenous protein was functional. We observed that over-expressed RNA Pol II LS was predominantly hypophosphorylated, soluble and accumulated in the cytoplasm in a CRM1-dependent manner. Our results further showed that the transcriptionally active form of RNA Pol II LS containing phosphoserine in position 2 of the CTD repeats was restricted to the nucleus and its levels remained remarkably constant. We propose that nucleo-cytoplasmic shuttling of RNA Pol II LS may provide a mechanism to control the pool of RNA polymerase subunits that is accessible for assembly of a functional enzyme in the nucleus. (c) 2006 Elsevier Inc. All rights reserved.