DNA methylation in Neuronal and Glial Differentiation

描述（由申请人提供）：DNA甲基化是一个主要的表观遗传因素，涉及基因调控、基因组印记和x染色体失活。DNA甲基化异常与几种人类智力障碍有关，包括Rett、ICF、Fragile-X和ATRX综合征。然而，人们对DNA甲基化变化如何扰乱神经功能并导致神经系统疾病知之甚少。我们研究的长期目标是阐明DNA甲基化在神经发育和功能中的作用。使用条件基因敲除方法，我们最近构建了一株突变小鼠，其维持甲基转移酶基因Dnmtl在中枢神经系统（CNS）前体细胞中被完全删除。中枢神经系统前体细胞Dnmtl缺乏导致分化神经元和神经胶质细胞发生显著的去甲基化。携带95%的低甲基化中枢神经系统细胞的突变胚胎在出生后立即死亡，这表明低甲基化破坏了动物生存的重要中枢神经系统功能。在胚胎中枢神经系统中携带30% Dnmtl-/-细胞的镶嵌动物中，突变细胞在出生后成熟过程中被选择性地消除，这表明甲基化对出生后中枢神经系统细胞的存活也很重要。本研究的目的是表征低甲基化脑中的神经缺陷，并确定DNA低甲基化影响神经元和神经胶质细胞存活和分化的分子机制。我们的工作假设是DNA低甲基化导致许多神经基因的不适当表达，从而导致中枢神经系统发育过程中的多种缺陷。因此，我们提出以下具体目标：目的：探讨DNA低甲基化对中枢神经系统前体细胞命运的影响。2. 确定DNA低甲基化是否影响神经元成熟和突触功能。3. 探讨出生后中枢神经系统环境中DNA低甲基化引发细胞死亡的机制。提出的研究可能为DNA甲基化在神经发育中的作用以及某些智力迟钝障碍的疾病机制提供基本见解。

DESCRIPTION (provided by applicant): DNA methylation is a major epigenetic factor involved in gene regulation, genomic imprinting, and X-chromosome inactivation. Aberrant DNA methylation has been associated with several human mental retardation disorders including Rett, ICF, Fragile-X, and ATRX syndromes. However, little is known about how DNA methylation changes perturb neural function and lead to neurological disorders. The long-term objective of our research is to elucidate the role of DNA methylation in neural development and function. Using the conditional gene knockout approach, we have recently constructed a strain of mutant mice in which the maintenance methyltransferase gene Dnmtl is deleted exclusively in precursor cells of the central nervous system (CNS). Dnmtl deficiency in CNS precursor cells causes significant demethylation in differentiating neurons and glial cells. Mutant embryos carrying 95 percent of hypomethylated CNS cells die immediately after birth, indicating that hypomethylation disrupts vital CNS function for animal survival. In mosaic animals carrying 30 percent of Dnmtl-/- cells in the embryonic CNS, mutant cells are selectively eliminated during postnatal maturation, showing that methylation is also important for the survival of postnatal CNS cells. The goal of this proposal is to characterize the neural defects in the hypomethylated brain and define the molecular mechanism by which DNA hypomethylation influences the survival and differentiation of neurons and glia. Our working hypothesis is that DNA hypomethylation results in inappropriate expression of many neural genes, which subsequently leads to multiple defects during CNS development. We therefore propose the following Specific Aims: 1. To determine the effect of DNA hypomethylation on the cell fate determination of CNS precursor cells. 2. To determine whether DNA hypomethylation affects neuronal maturation and synaptic function. 3. To define the mechanism of cell death triggered by DNA hypomethylation in the postnatal CNS environment. The proposed study may provide fundamental insights into the role of DNA methylation in neural development as well as the disease mechanism underlying certain mental retardation disorders.