DNA methylation in Neuronal and Glial Differentiation

描述（由申请人提供）：DNA甲基化是一种主要的表观遗传因素，参与基因调控、基因组印记和X染色体失活。异常的DNA甲基化与几种人类精神发育迟滞疾病相关，包括Rett、ICF、脆性X和ATRX综合征。然而，人们对DNA甲基化改变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。使用条件基因敲除的方法，我们最近构建了一个菌株的突变小鼠中，维持甲基转移酶基因Dnmtl被删除专门在前体细胞的中枢神经系统（CNS）。CNS前体细胞中的Dnmtl缺陷导致分化的神经元和神经胶质细胞中的显著去甲基化。携带95%低甲基化CNS细胞的突变胚胎在出生后立即死亡，表明低甲基化破坏了动物生存的重要CNS功能。在胚胎CNS中携带30% Dnmtl-/-细胞的嵌合体动物中，突变细胞在出生后成熟过程中被选择性消除，表明甲基化对出生后CNS细胞的存活也很重要。该提案的目标是描述低甲基化脑中的神经缺陷，并定义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CNS发育过程中的多种缺陷。因此，我们提出以下具体目标：1.确定DNA低甲基化对CNS前体细胞的细胞命运决定的影响。2.确定DNA低甲基化是否影响神经元的成熟和突触功能。3.明确出生后CNS环境中DNA低甲基化引发细胞死亡的机制。这项研究可能为DNA甲基化在神经发育中的作用以及某些精神发育迟滞疾病的发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.