Role of DNA methyltransferases in Huntington's disease

摘要 亨廷顿氏病（HD）是一种破坏性的和总是致命的神经退行性疾病，其特征在于 纹状体和皮质中特定神经元的进行性萎缩和丧失，导致运动、认知和 精神疾病对潜在的疾病机制仍然知之甚少，目前还没有治愈方法 存在于这种疾病中。我们迫切需要了解导致人类死亡的分子机制。 HD神经元，以便利用这些机制来挽救这些垂死的神经元。转录 失调是HD过程中的早期分子异常， 神经变性和疾病进展。尽管新出现的证据表明， HD中不同的表观遗传修饰，在转录调控中具有因果作用的关键表观遗传修饰， 变化和神经退行性变仍然在很大程度上未知。DNA甲基化是一种主要的表观遗传修饰， 最近显示在突变的Htt表达细胞和HD患者的脑中受到干扰。重要的是， 我们最近的研究结果表明，DNA甲基转移酶（DNMT）是催化DNA甲基化的酶， 在突变HD蛋白（亨廷顿蛋白）诱导的神经毒性中具有重要功能。的根本目标 该建议是鉴定DNMT在神经元功能障碍和死亡中的分子调节和作用， 使用小鼠和人类培养的神经元以及HD的小鼠模型。我们的假设是 DNA甲基化是HD中的显性表观遗传事件，其驱动对HD重要的基因的失调。 神经元功能和存活，从而导致HD中的神经元功能障碍和死亡。瞄准这一 因此，表观遗传途径可以防止疾病进展。为了验证这一假设，我们将继续 以下具体目标：1）确定突变体Htt如何诱导异常DNA甲基化，重点是DNMT 功能; 2）确定DNMT在小鼠体内HD发病机制中的作用;和3）鉴定DNMT的作用机制。 DNMT抑制介导的体外和体内突变型Htt表达神经元的神经保护作用。我们将采取 从小鼠脑中分离细胞类型特异性RNA和DNA以确定HD特异性 体内疾病易感神经元的DNA甲基化和转录变化。我们的贡献是 预期使用疾病相关的神经系统建立DNMT在HD发病机制中的关键作用 和体内遗传小鼠模型，长期目标是发现潜在的治疗靶点， HD中的神经变性。考虑到在其他细胞中观察到转录和DNA甲基化的改变， 神经退行性疾病，精神疾病，衰老，学习和记忆，拟议的研究 这对广泛的人类神经系统状况以及正常的大脑功能都有影响。在一起， 我们研究了一种新的表观遗传学机制，这种机制是突变型Htt诱导的转录失调的基础。 和神经退行性疾病将为神经退行性疾病领域的基本问题提供答案。 疾病

ABSTRACT Huntington’s disease (HD) is a devastating and invariably fatal neurodegenerative disease characterized by progressive atrophy and loss of specific neurons in the striatum and cortex, leading to motor, cognitive, and psychiatric disorders. The underlying disease mechanism remains poorly understood, and currently, no cure exists for this disease. There is an urgent need to understand the molecular mechanisms driving the death of HD neurons, so that these mechanisms can be harnessed to save these dying neurons. Transcriptional dysregulation is an early molecular abnormality in the course of HD and is thought to contribute to neurodegeneration and disease progression. Although emerging evidence indicates altered patterns of several different epigenetic modifications in HD, key epigenetic modifications that have a causal role in transcriptional changes and neurodegeneration remain largely unknown. DNA methylation, a major epigenetic modification, has recently been shown to be perturbed in mutant Htt-expressing cells and brains of HD patients. Importantly, our recent findings suggest that DNA methyltransferases (DNMTs), enzymes that catalyze DNA methylation, are of functional importance in mutant HD protein (huntingtin)-induced neurotoxicity. The fundamental objective of this proposal is to identify the molecular regulation and role of DNMTs in neuronal dysfunction and death, using mouse and human cultured neurons as well as mouse models of HD. Our hypothesis is that abnormal DNA methylation is a dominant epigenetic event in HD, which drives the dysregulation of genes important for neuronal function and survival, thereby contributing to neuronal dysfunction and death in HD. Targeting this epigenetic pathway may therefore prevent disease progression. To test this hypothesis, we will pursue the following specific aims: 1) Determine how mutant Htt induces aberrant DNA methylation with a focus on DNMT function; 2) Determine the role of DNMTs in HD pathogenesis in mice in vivo; and 3) Identify the mechanism of DNMT inhibition-mediated neuroprotection in mutant Htt-expressing neurons in vitro and in vivo. We will take innovative approaches to isolate cell-type specific RNA and DNA from mouse brain to determine HD-specific DNA methylation and transcription changes in disease-vulnerable neurons in vivo. Our contribution here is expected to establish the critical role of DNMTs in HD pathogenesis using a disease-relevant neuronal system and genetic mouse models in vivo, with the long-term goal of discovering potential therapeutic targets to prevent neurodegeneration in HD. Given the observation of altered transcription and DNA methylation in other neurodegenerative diseases, psychiatric disorders, aging, and learning and memory, the proposed studies have implications for a wide-range of human nervous system conditions as well as normal brain function. Together, our examination of a novel epigenetic mechanism underlying mutant Htt-induced transcriptional dysregulation and neurodegeneration will provide answers to fundamental questions in the field of neurodegenerative diseases.