Aging and brain 5-lipoxygenase

描述(由申请人提供)：表观遗传机制，包括DNA甲基化和组蛋白修饰，深刻影响基因表达，并似乎在衰老时发生变化。更好地了解大脑中的这些机制可能会为治疗/预防与衰老相关的中枢神经系统疾病指明新的靶点。在过去四年的资助中，该实验室的研究证实，大脑中5-脂氧合酶(5-LOX)的表达在衰老过程中增加，受谷氨酸受体激活和糖皮质激素的刺激，可能与神经退化有关，可能与阿尔茨海默病(AD)有关。其他研究表明，在阿尔茨海默病小鼠模型Tg2576小鼠中，5-LOX基因敲除可以减少淀粉样变性。最近的初步数据表明，随着5-LOX启动子中CpG岛甲基化状态的改变(例如，通过低甲基化药物5-氮杂-2‘-脱氧胞苷)或改变组蛋白乙酰化(例如，通过组蛋白脱乙酰酶-HDACs-抑制剂)，神经元5-LOX的表达增加。在这个方案中，我们假设老化的脑神经元的表观遗传机制发生了改变，并负责调节大脑5-LOX的表达；5-LOX的表达是由5-LOX启动子的甲基化减少和/或5-LOX基因的组蛋白乙酰化和甲基化改变而触发的。我们提出了以下三个具体目标：1)研究衰老对小鼠大脑DNMT1和HDACs表达的影响，b)脑区特异性5-LOX启动子的甲基化，以及c)5-LOX相关的组蛋白乙酰化和甲基化；2)在原代神经元培养中，测试细胞成熟/老化对神经元DNMT1和HDACs表达、5-LOX启动子甲基化和5-LOX相关组蛋白乙酰化和甲基化的影响；3)利用原代神经元培养，研究DNMT1和HDACs抑制/敲除在5-LOX表达中的作用。这项拨款提案中概述的研究旨在提供相关数据，支持我们的假设，即表观遗传神经元改变是一个假定因素，使老化的大脑表现出5-LOX基因的上调表达。拟议中的实验可能会证实表观遗传机制与大脑老化有关的假设。

DESCRIPTION (provided by applicant): Epigenetic mechanisms that include DNA methylation and histone modifications profoundly influence gene expression and also appear to be altered in aging. A better understanding of these mechanisms in the brain may point to novel targets for the therapy/prevention of aging-associated central nervous system pathologies. Over the last four years of funding, studies from this laboratory have established that the brain expression of 5-lipoxygenase (5-LOX), an inflammatory enzyme, increases during aging, is stimulated by glutamate receptor activation and by glucocorticoids, and might be associated with neurodegeneration, possibly in Alzheimer's disease (AD). Others have shown that 5-LOX knockout in a mouse model of Alzheimer's disease, the Tg2576 mouse, and decreases amyloidosis. Recent preliminary data indicate that neuronal 5-LOX expression increases following changes in the methylation state of CpG islands in 5-LOX promoter (e.g., by a hypomethylating drug 5-aza-2'-deoxycytidine) or after altered histone acetylation (e.g., by histone deacetylases - HDACs - inhibitors). In this proposal, we hypothesize that epigenetic mechanisms are altered in aging brain neurons and are responsible for the regulation of brain 5-LOX expression; 5-LOX expression is triggered by decreased methylation at the 5-LOX promoter and/or altered histone acetylation and methylation at the 5-LOX gene. We propose the following three specific AIMs: 1) Investigate in mice the effects of aging on a) brain DNMT1 and HDACs expression, b) brain region-specific 5-LOX promoter methylation, and c) 5-LOX-related histone acetylation and methylation; 2) In primary neuronal cultures, test the in-vitro effects of cell maturation/aging on neuronal DNMT1 and HDACs expression, 5-LOX promoter methylation, and 5-LOX-related histone acetylation and methylation; and 3) Using primary neuronal cultures, investigate the role of DNMT1 and HDACs inhibition/knockdown in 5-LOX expression. The research outlined in this grant proposal is designed to provide relevant data in support of our hypothesis that an epigenetic neuronal alteration is a putative factor that predisposes the aging brain to display an upregulated expression of the 5-LOX gene. The proposed experiments may corroborate the hypothesis that epigenetic mechanisms are involved in brain aging.