Characterization of MeCP2 target genes in Rett Syndrome

甲基- cpg结合蛋白2 （Mecp2/ Mecp2）被认为在哺乳动物基因组中选择性结合甲基- cpg二核苷酸，并通过与SinSA相互作用和募集组蛋白去乙酰化酶（Hdac）在体内发挥转录抑制作用。MECP2基因突变与Rett综合征（一种x连锁神经发育障碍）有关。我们最近发现母系表达的印迹基因Dlx5是小鼠大脑和Rett综合征个体淋巴细胞中Mecp2的直接靶基因。DLX5显示出印迹丢失。结果，当Mecp2缺失或突变时，Dlx5的表达增加2倍。我们还报道了Mecp2通过在转录沉默的染色质中形成一个染色质环来调节基因。DLX5调节氨基丁酸（GABA）的产生。利用表达DLX5水平升高的转基因小鼠，我们拟研究DLX5 /DLX5失调本身是否足以引起Rett综合征的某些神经表型。我们将通过对DLX5转基因小鼠的系统行为分析来研究这个问题。我们将研究Dlx5和Gad（一种合成GABA的酶）以及GABA本身在野生型、Mecp2-null和Dlx5转基因小鼠大脑各亚区中的表达（Specific Aim 1和2）。除了Dlx5，我们最近发现了另一个印迹基因，Peg3，在mecp2缺失的大脑的海马体中被失调。我们将研究Peg3是否也是Mecp2的直接靶基因，如果是，我们将确定Mecp2如何调节该基因的表达（Specific Aim 3）。由于已知Peg3与母性行为有关，我们将评估大脑中表达Peg3水平升高的Mecp2（+/-）雌性小鼠的母性行为。此外，我们将通过体外分化细胞培养系统评估Peg3在肌生成中的过表达（Specific Aim 4）。这是因为Peg3在成年小鼠的大脑和骨骼肌中特异且丰富地表达。我们的研究将提供Mecp2活性的分子机制以及Mecp2突变如何导致Rett综合征的信息。

DESCRIPTION (provided by applicant): D. Methyl-CpG binding protein 2 (Mecp2/MECP2) is thought to selectively bind methyl-CpG dinucleotides in the mammalian genome and to function as a transcriptional represser in vivo by interacting with SinSA and recruiting histone deaceylase (Hdac). Mutations in MECP2 are associated with Rett syndrome, an X-linked neurodevelopmental disorder. We recently found that a maternally expressed imprinted gene, Dlx5, is a direct target gene for Mecp2 in mouse brain and in lympholastoid cells from individuals with Rett syndrome. DLX5 showed a loss of imprinting. As a result, Dlx5 expression is increased 2-fold when Mecp2 is absent or mutated. We also reported that Mecp2 regulates genes by forming a chromatin loop specifically in transcriptionally silent chromatin. DLX5 regulates the production of (-aminobutyric acid (GABA). Using transgenic mice expressing increased levels of DLX5, we propose to study whether Dlx5/DLX5 dysregulation per se is sufficient to cause some of the neurological phenotypes of Rett syndrome. We will investigate this question by systematic behavioral analyses of the DLX5 transgenic mice. We will study expression of Dlx5 and Gad, an enzyme which synthesizes GABA, as well as GABA itself, in various subregions of the brains of wild-type, Mecp2-null, and DLX5 transgenic mice (Specific Aim 1 and 2). In addition to Dlx5, we recently identified another imprinted gene, Peg3, to be dysregulated in the hippocampus of the Mecp2-null brain. We will study whether Peg3 is also a direct target gene for Mecp2, and if it is, we will determine how Mecp2 regulates expression of this gene (Specific Aim 3). Because Peg3 is known to be linked to maternal behaviors, we will evaluate the maternal behaviors of Mecp2 (+/-) female mice expressing increased levels of Peg3 in their brain. Furthermore, we will evaluate Peg3 overexpression in myogenesis by the in vitro differentiation cell culture system (Specific Aim 4). This is because Peg3 is specifically and abundantly expressed in the brain and skeletal muscle in adult mice. Our study will provide information about the molecular mechanisms underlying Mecp2 activity and how MECP2 mutations might cause Rett syndrome.