ROLE OF ROS IN HYPOXIA-MEDIATED REGULATION OF THE PHENYLETHANOLAMINE N-METHYLTRANSFERASE GENE

* 氧是哺乳动物细胞中正常细胞功能和体内平衡的关键组分。 哺乳动物能够引起对减少的氧气的应激反应，以促进去除或适应缺氧。 哺乳动物的应激反应是通过激活下丘脑-垂体-肾上腺（HPA）轴和交感-肾上腺（SA）轴介导的，导致释放应激激素，皮质酮/皮质醇和肾上腺素。 肾上腺素主要由肾上腺的嗜铬细胞合成和释放，是负责“战斗或逃跑反应”的神经递质/神经激素。 虽然肾上腺素合成可以通过HPA和SA轴调节以响应缺氧应激，但研究表明肾上腺嗜铬细胞是氧敏感的，因此可以调节稳态机制，包括不依赖于激素和神经激活的儿茶酚胺生物合成。 这在胎儿发育过程中，在嗜铬细胞的交感神经支配之前是至关重要的。 迄今为止的研究支持活性氧（ROS）参与细胞对缺氧的反应。 此外，最近的研究表明，氧化应激和ROS改变表观遗传基因调控机制。 然而，活性氧在参与肾上腺素合成调节的细胞机制中的作用，特别是PNMT基因的表观遗传调节尚不清楚。 本研究将利用细胞到系统生物学的方法来研究缺氧在PNMT基因调控中的作用。利用体外PC 12细胞培养模型和先进的体外细胞和分子技术，参与调节PNMT基因对缺氧和ROS的细胞和分子机制将被描绘。 此外，还将研究表观遗传调节因子在介导缺氧细胞反应中的作用。 此外，在体内啮齿动物模型的缺氧暴露将被用来检查是否在体外鉴定的分子调控机制参与整个生物体的反应，缺氧应激。 这项资助的结果将为缺氧反应所涉及的基本细胞过程提供新的见解。 此外，它还将提供洞察应激激素，肾上腺素，在哺乳动物应激反应和适应缺氧的作用。

***Oxygen is a critical component of normal cellular function and homeostasis in mammalian cells. Mammals are capable of eliciting a stress-response to reduced oxygen to facilitate either removal or adaptation to hypoxia. The mammalian stress-response is mediated via activation of the hypothalamic-pituitary-adrenal (HPA) axis and the sympatho-adrenal (SA) axis, resulting in the release of the stress hormones, cortisosterone/cortisol and adrenaline. Adrenaline is synthesized and released predominantly by the chromaffin cells of the adrenal glands and is the neurotransmitter/neurohormone responsible for the “fight or flight response”. Although adrenaline synthesis may be regulated via the HPA and SA axis in response to hypoxic stress, studies have shown that adrenal chromaffin cells are oxygen sensitive and may therefore regulate homeostatic mechanism, including catecholamine biosynthesis, independent of hormonal and neural activation. This is critically important during fetal development prior to sympathetic innervation of chromaffin cells. Studies to date support a role of reactive oxygen species (ROS) is involved in the cellular responses to hypoxia. Furthermore, recently reported studies suggest that oxidative stress and ROS alters epigenetic gene regulation mechanism. However the role of ROS in cellular mechanisms involved in the regulation of the adrenaline synthesis and in particular epigenetic regulation of the PNMT gene is not known. This proposal will utilize a cell to systems biology approach to examine the role of hypoxia in the regulation of the PNMT gene. Utilizing an in-vitro PC12 cell culture model and advanced in vitro cellular and molecular techniques, the cellular and molecular mechanism involved in the regulation of the PNMT gene in response to hypoxia and ROS will be delineated. In addition, the role of epigenetic regulators in mediating the hypoxic cellular response will also be investigated. Furthermore, in vivo rodent models of hypoxia exposure will be utilized to examine the whether the molecular regulatory mechanisms identified in-vitro are involved in the whole organism's response to hypoxic stress. The results from this grant will provide new insight into the fundamental cellular processes involved in response to hypoxia. In addition, it will also provide insight into the role of stress the hormone, adrenaline, in the mammalian stress response to and in the adaptation to hypoxia.