Ultraviolet radiation alters the phosphorylation of RNA polymerase II large subunit and accelerates its proteasome-dependent degradation
Ultraviolet radiation alters the phosphorylation of RNA polymerase II large subunit and accelerates its proteasome-dependent degradation
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DOI：
10.1016/s0921-8777(01)00097-0
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发表时间：
2001-09-04
期刊：
影响因子：
--
通讯作者：
Bregman, DB
中科院分区：
文献类型：
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作者：
Luo, ZH;Zheng, JH;Bregman, DB
已经表明，紫外线（UV）辐射诱导RNA聚合酶II大亚基（RNAP II-LS）的泛素化以及其蛋白酶体降解。在哺乳动物细胞中的研究表明，RNAP II-LS的高度磷酸化形式优先泛素化，但在酿酒酵母中的研究提供了证据，未磷酸化的RNAP II-LS是一个同样合适的底物。在本研究中，使用识别所有形式RNAP II-LS的抗体（ARNA-3），无论其C-末端结构域（CTD）的磷酸化状态如何，以评估在基础条件下或UV-C（10 J/m2）照射后人成纤维细胞中总细胞RNAP II-LS的降解。结果发现，紫外线辐射迅速转移RNAP II-LS的磷酸化模式从去磷酸化和磷酸化形式的混合物，完全更多的磷酸化形式。这种磷酸化状态的转变并没有被ERK或p38通路的药理学抑制所阻断，这两者都与细胞UV反应有关。除了改变磷酸化概况，UV辐射导致总RNAP II-LS的净降解。在转录和CTD激酶抑制剂DRB的存在下，UV诱导的RNAP II-LS降解也大大减少。使用面板。蛋白酶抑制剂，它表明，大部分紫外线诱导的降解是蛋白酶体依赖性的。然而，UV诱导的低磷酸化RNAP II-LS的损失是蛋白酶体无关的。最后，当与适当的对照相比时，UV辐射诱导互补组A或B（CSA或CS B）的Cockayne综合征（CS）细胞中所有过度磷酸化RNAP II-LS的类似转变。当比较CSA或CSB修复主管对照细胞时，RNAP II-LS的UV诱导降解速率没有显著改变。细胞紫外线响应的影响进行了讨论。(C)2001 Elsevier Science B.V保留所有权利。
It has been shown that ultraviolet (UV) radiation induces the ubiquitination of the large subunit of RNA polymerase II (RNAP II-LS) as well as its proteasomal degradation. Studies in mammalian cells have indicated that highly phosphorylated forms of RNAP II-LS are preferentially ubiquitinated, but studies in Saccharomyces cerevisiae have provided evidence that unphosphorylated RNAP II-LS is an equally suitable substrate. In the present study, an antibody (ARNA-3) that recognizes all forms of RNAP II-LS, regardless of the phosphorylation status of its C-terminal domain (CTD), was utilized to evaluate the degradation of total cellular RNAP II-LS in human fibroblasts under basal conditions or after UV-C (10 J/m(2)) irradiation. It was found that UV radiation rapidly shifted the phosphorylation profile of RNAP II-LS from a mixture of dephosphorylated and phosphorylated forms to entirely more phosphorylated forms. This shift in phosphorylation status was not blocked by pharmacologic inhibition of either the ERK or p38 pathways, both of which have been implicated in the cellular UV response. In addition to shifting the phosphorylation profile, UV radiation led to net degradation of total RNAP II-LS. UV-induced degradation of RNAP II-LS was also greatly reduced in the presence of the transcriptional and CTD kinase inhibitor DRB. Using a panel. of protease inhibitors, it was shown that the bulk of UV-induced degradation is proteasome-dependent. However, the UV-induced loss of hypophosphorylated RNAP II-LS was proteasome-independent. Lastly, UV radiation induced a similar shift to all hyperphosphorylated RNAP II-LS in Cockayne syndrome (CS) cells of complementation groups A or B (CSA or CSB) when compared to appropriate controls. The UV-induced degradation rates of RNAP II-LS were not significantly altered when comparing CSA or CSB to repair competent control cells. The implications for the cellular Uv response are discussed. (C) 2001 Elsevier Science B.V All rights reserved.