Haffey Wendy D, Mikhaylova Olga, Meller Jarek, Yi Ying, Greis Kenneth D, Czyzyk-Krzeska Maria F
Department of Cancer and Cell Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45237-0505, USA.
Adv Enzyme Regul. 2009;49(1):121-32. doi: 10.1016/j.advenzreg.2008.12.004. Epub 2008 Dec 31.
The large subunit of RNA Polymerase II, Rpb1, undergoes hydroxylation on proline 1465, which in turn triggers Ser5 hydroxylation. While Egln2 prolyl hydroxylase appears to mediate P1465 hydroxylation, Egln1 has an inhibitory activity and its knockdown stimulates constitutive hydroxylation and Ser5 phosphorylation of Rpb1, but only in cells that are VHL(+). In this study we have analyzed protein factors affected by the knockdown of Egln1 in VHL(+) and VHL(−) cells. We found that, in VHL(+) cells, several proteins were inhibited but none were induced by Egln2 knockdown. The function of several of those proteins was related to calcium metabolism and the cytoskeleton. In contrast, in VHL(−) cells Egln1 knockdown caused upregulation of several mitochondrial proteins including subunits of ATP synthase. Several of the proteins repressed in VHL(−) cells by Egln1 knockdown were involved in the function of RNA polymerase II during transcription from chromatin templates. These data suggest that the effects of Egln1 knockdown depend on the status of pVHL and can be correlated with effects on Rpb1.
RNA聚合酶II的大亚基Rpb1在脯氨酸1465处发生羟基化，这进而引发丝氨酸5的羟基化。虽然Egln2脯氨酰羟化酶似乎介导P1465的羟基化，但Egln1具有抑制活性，其敲低会刺激Rpb1的组成型羟基化和丝氨酸5磷酸化，但仅在VHL(+)细胞中如此。在本研究中，我们分析了VHL(+)和VHL(−)细胞中受Egln1敲低影响的蛋白质因子。我们发现，在VHL(+)细胞中，几种蛋白质受到抑制，但Egln2敲低未诱导任何蛋白质。其中几种蛋白质的功能与钙代谢和细胞骨架有关。相反，在VHL(−)细胞中，Egln1敲低导致几种线粒体蛋白质上调，包括ATP合酶的亚基。在VHL(−)细胞中被Egln1敲低抑制的几种蛋白质参与了从染色质模板转录过程中RNA聚合酶II的功能。这些数据表明，Egln1敲低的影响取决于pVHL的状态，并且可以与对Rpb1的影响相关联。
