The von hippel-lindau tumor suppressor protein and Egl-9-type proline hydroxylases regulate the large subunit of RNA polymerase II in response to oxidative stress
The von hippel-lindau tumor suppressor protein and Egl-9-type proline hydroxylases regulate the large subunit of RNA polymerase II in response to oxidative stress
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DOI：
10.1128/mcb.01231-07
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发表时间：
2008-04-01
影响因子：
5.3
通讯作者：
Czyzyk-Krzeska, Maria F.
中科院分区：
文献类型：
--
作者：
Mikhaylova, Olga;Ignacak, Monika L.;Czyzyk-Krzeska, Maria F.
人肾透明细胞癌(RCC)常与von Hippel-Lindau(VHL)肿瘤抑制基因(PVHL)缺失有关，pVHL可抑制泛素化和低表达转录因子α亚基的降解。PVHL还泛素化RNA聚合酶11的大亚基Rpb1，在C末端结构域(CTD)的丝氨酸5(Ser5)上磷酸化。位于CTD N端的LXXLAP基序中的羟化脯氨酸1465允许Rpb1与pVHL相互作用。在此，我们报道，在肾癌细胞中，pVHL调节Rpb1的表达，对于低级氧化应激诱导Rpb1重新聚集到DNA参与的部分及其P1465羟化、磷酸化和非降解性泛素化是必需的。氧化应激使VHL+RCC细胞染色质部分的Egin-9型脯氨酸羟基酶Phd1和PHD2与Rpb1共沉淀，PHD1是P1465羟化所必需的，而PHD2具有抑制作用。P1465羟化是氧化应激诱导的Rpb1的Ser5磷酸化所必需的。重要的是，野生型Rpb1的过表达促进了VHL+细胞形成肾脏肿瘤，这种作用被Rpb1的P1465A突变所消除。这些数据表明，pVHL可能通过这一涉及Rbp1的P1465羟化和Ser5磷酸化的新途径来调控肿瘤的生长。
Human renal clear cell carcinoma (RCC) is frequently associated with loss of the von Hippel-Lindau (VHL) tumor suppressor (pVHL), which inhibits ubiquitylation and degradation of the alpha subunits of hypoxiainducible transcription factor. pVHL also ubiquitylates the large subunit of RNA polymerase 11, Rpbl, phosphorylated on serine 5 (Ser5) within the C-terminal domain (CTD). A hydroxylated proline 1465 within an LXXLAP motif located N-terminal to the CTD allows the interaction of Rpbl with pVHL. Here we report that in RCC cells, pVHL regulates expression of Rpb1 and is necessary for low-grade oxidative-stress-induced recruitment of Rpbl to the DNA-engaged fraction and for its P1465 hydroxylation, phosphorylation, and nondegradative ubiquitylation. Egin-9-type prolyl hydroxylases, PHD1 and PHD2, coimmunoprecipitated with Rpb1 in the chromatin fraction of VHL+ RCC cells in response to oxidative stress, and PHDI was necessary for P1465 hydroxylation while PHD2 had an inhibitory effect. P1465 hydroxyllation was required for oxidativestress-induced Ser5 phosphoryllation of Rpb1. Importantly, overexpression of wild-type Rpb1 stimulated formation of kidney tumors by VHL+ cells, and this effect was abolished by P1465A mutation of Rpb1. These data indicate that through this novel pathway involving P1465 hydroxylation and Ser5 phosphorylation of Rbp1, pVHL may regulate tumor growth.