GR-Mediated Epigenetic Regulation of the CRH Gene

描述(由申请者提供)：美国每年有1900万人经历抑郁症。抑郁症是一种潜在的致命疾病，给家庭成员带来压力，导致在学校和工作中损失时间，治疗费用高昂，并给社会带来巨大负担。有鉴于此，令人惊讶的是，抑郁症的发病机制仍然知之甚少。这种疾病的一个明显特征--抑郁与对压力的异常反应高度相关。应激反应由下丘脑-垂体-肾上腺(HPA)轴介导。HPA轴的活动通常受到严格调控，这在很大程度上是因为最终产物糖皮质激素是系统强有力的下行调节物质。在抑郁症中，下丘脑中合成和分泌触发应激反应的多肽-促肾上腺皮质激素释放激素(CRH)的神经元对糖皮质激素下调不敏感。因为这些神经元是中枢神经系统和荷尔蒙环境输入的最终共同积分器，如果它们有异常的反应，轴的整个功能就会受到负面影响。这项建议中描述的实验旨在阐明糖皮质激素下调CRH基因(CRH)表达的机制。AIMS 1和2利用了一种相对较新和功能强大的技术-染色质免疫沉淀(CHIP)和一种相对较新的神经元细胞系(IVB)，它具有下丘脑CRH细胞的许多特征。AIM 1的设计目的是确定CRH表达下调需要哪些共调控蛋白阵列。目的2旨在确定染色质修饰酶及其表观遗传标记在调节CRH中所起的作用。在目标3中，这项工作将在活体环境中进行。从AIMS 1和AIMS 2获得的数据将通过缩小选择进行分析的可能候选者的阵列来指导体内工作。我们将研究两个活体环境。首先，将在皮质酮(CORT)的昼夜高峰和低谷评估辅调节因子和组蛋白修饰酶的模式。这些实验将有助于分析皮质醇水平的生理变化对辅调节因子和组蛋白修饰酶的影响。其次，大鼠将在较短的时间点给药，并评估与昼夜节律研究相同的参数。综上所述，这些研究将允许对调节应激反应的表观遗传机制进行分子分析。这种研究抑郁症的独特方法组合将产生一系列新的数据，使我们更好地理解HPA的调节机制，并提高我们识别治疗抑郁症的新药物靶点的能力。

DESCRIPTION (provided by applicant): Nineteen million people a year in the United States experience depression. A potentially lethal disease, depression puts a strain on family members, leads to lost hours at school and work, is costly to treat, and places a substantial burden on society. In light of this, it is surprising that the pathogenesis of depression is still poorly understood. One feature of the illness that is clear - depression is highly correlated with an abnormal response to stress. The stress response is mediated by the hypothalamic-pituitary-adrenal (HPA) axis. Activity of the HPA axis is normally tightly regulated, in large part because the end products, glucocorticoids, are potent down- regulators of the system. In depression, neurons in the hypothalamus that synthesize and secrete the peptide that triggers the stress response, corticotropin-releasing hormone (CRH), are insensitive to glucocorticoid down-regulation. Because these neurons are the final common integrators of inputs from the central nervous system and the hormonal milieu, if they are abnormally responsive, the entire functioning of the axis is negatively affected. The experiments described in this proposal are designed to elucidate mechanisms by which glucocorticoids down-regulate expression of the CRH gene (crh). Aims 1 and 2 take advantage of a relatively new and powerful technique, chromatin immunoprecipitation (ChIP), and a relatively new neuronal cell line (IVB), which has many features of CRH cells in the hypothalamus. Aim 1 is designed to determine which arrays of co-regulatory proteins are required for down-regulation of crh expression. Aim 2 is designed to determine the role that chromatin modification enzymes and their epigenetic marks play in regulating crh. In Aim 3, the work will be taken into an in vivo setting. Data gained from Aims 1 and 2 will guide the in vivo work by narrowing the array of possible candidates to be chosen for analysis. Two in vivo settings will be studied. First, patterns of coregulators and histone modification enzymes will be assessed at the circadian peak and trough of corticosterone (Cort). These experiments will permit analysis of the effect physiological changes in Cort levels exert on coregulators and histone modification enzymes. Second, rats will be administered metyrapone at short time points, and the same parameters assessed as in the circadian studies. Taken together, the studies will permit molecular analysis of epigenetic mechanisms that regulate the stress response. This unique combination of approaches to the study of depression will produce a novel array of data, leading to a greater understanding of mechanisms of HPA regulation, and increasing our ability to identify novel drug targets for the treatment of depression.