Ignacak M L, Harbaugh S V, Dayyat E, Row B W, Gozal D, Czyzyk-Krzeska M F
Department of Cancer and Cell Biology, University of Cincinnati, Cincinnati, OH 45267-0505, USA.
Neuroscience. 2009 Feb 18;158(4):1436-45. doi: 10.1016/j.neuroscience.2008.11.025. Epub 2008 Nov 21.
Intermittent hypoxia (IH) is a major pathological factor in the development of neural deficits associated with sleep-disordered breathing. Here we demonstrate that IH lasting 2 or 30 days, but not sustained hypoxia (SH) of the same duration, was accompanied by several posttranslational modifications of the large subunit of RNA polymerase II, Rpb1, including hydroxylation of proline 1465, phosphorylation of serine 5 residues within the C-terminal domain, and nondegradative ubiquitylation. These modifications were found to occur in two regions of the brain, hippocampal region CA1 and the prefrontal cortex, but not in neocortex, brainstem and CA3 region of hippocampus. We also found that mice exposed to 14 or 30 days of IH, but not SH, demonstrated cognitive deficits in behavioral assays. Furthermore, by using the pheochromocytoma-derived PC12 cell line, we showed that, under in vitro IH conditions, induction of Rpb1 hydroxylation, phosphorylation, and ubiquitylation required that the von Hippel-Lindau protein be present. We hypothesize that the observed modifications of Rpb1 participate in regulating the expression of genes involved in mediating cognitive deficits evoked by chronic IH.
间歇性缺氧（IH）是与睡眠呼吸紊乱相关的神经功能缺损发展过程中的一个主要病理因素。在此，我们证明持续2天或30天的IH，而非相同持续时间的持续性缺氧（SH），伴随着RNA聚合酶II大亚基Rpb1的几种翻译后修饰，包括脯氨酸1465的羟基化、C末端结构域内丝氨酸5残基的磷酸化以及非降解性泛素化。这些修饰发生在大脑的两个区域，海马区CA1和前额叶皮层，但在新皮层、脑干和海马CA3区未发现。我们还发现，暴露于14天或30天IH而非SH的小鼠在行为试验中表现出认知缺陷。此外，通过使用嗜铬细胞瘤衍生的PC12细胞系，我们表明，在体外IH条件下，Rpb1羟基化、磷酸化和泛素化的诱导需要冯·希佩尔-林道蛋白的存在。我们推测，观察到的Rpb1修饰参与调节介导慢性IH诱发的认知缺陷的相关基因的表达。
