Neuronal Activity-dependent Regulation of MeCP2 Function

描述（由申请人提供）：Rett综合征（RTT）是一种具有已知遗传原因的自闭症谱系障碍（ASD），是女性精神发育迟滞的主要原因之一。RTT是由编码甲基CpG结合蛋白2（MeCP 2）的X连锁基因突变引起的。RTT的发病后，正常的早期出生后的发展和学习的语言和运动技能的急剧损失提出了一个假设，RTT的临床特征的活动依赖性神经元发育失败的结果。最近，我们发现MeCP2在没有神经元刺激的情况下抑制脑源性神经营养因子（BDNF）的表达。在刺激的存在下，MeCP2经历CaMKII介导的磷酸化并释放对Bdnf的抑制。我们已经表征了MeCP2上的磷酸化位点（S421），其选择性地感知神经元活性以控制BDNF转录，调节树突生长和棘成熟。我们的研究结果挑战了经典的观点MeCP2作为一个全球性的转录抑制因子，并牵连MeCP2在控制经验依赖性神经元发育的分子程序。然而，尚不清楚S421的磷酸化如何控制MeCP2的功能。此外，开发一种MeCP2的活性依赖性磷酸化被破坏的动物模型将为解决MeCP2在神经元发育中的作用提供最终工具。因此，我们计划使用生物化学，遗传学，成像和分子生物学技术来解决两个具体目标：1）表征MeCP2对基因表达的活性依赖性调节的分子机制。2)通过生成MeCP2 S421A基因敲入小鼠模型，检测活性依赖性MeCP2磷酸化对神经系统功能的体内贡献。我们将在指导阶段启动我们的目标，我将在这个奖项的独立阶段进行表征。我计划在不久的将来建立一个独立的研究项目，专注于RTT和ASD等神经系统疾病的生物学。我们希望，拟议的实验将提供一个更好地了解MeCP2功能，深入了解活性依赖性基因表达和神经元发育的机制，并提供新的机会，为发展治疗策略，以减轻RTT病理。

DESCRIPTION(provided by the applicant) : Rett Syndrome (RTT) is one of the Autism Spectrum Disorders (ASDs) with a known genetic cause and represents one of the leading causes of mental retardation in females. RTT is caused by mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MeCP2). The onset of RTT after normal early postnatal development and the precipitous loss of learned language and motor skills suggest a hypothesis that the clinical features of RTT result from a failure of activity-dependent neuronal development. Recently we discovered that MeCP2 suppresses Brain Derived Neurotrophic Factor (BDNF) expression in the absence of neuronal stimuli. In the presence of stimuli, MeCP2 undergoes CaMKII-mediated phosphorylation and releases repression to Bdnf. We have characterized a phosphorylation site (S421) on MeCP2 that selectively senses neuronal activity to control Bdnf transcription, modulate dendritic outgrowth and spine maturation. Our findings challenged the canonical view of MeCP2 as a global transcriptional represser and implicated MeCP2 in the molecular program controlling experience-dependent neuronal development. However, it is not clear how phosphorylation of S421 controls the function of MeCP2. In addition, developing an animal model where activity-dependent phosphorylation of MeCP2 is disrupted will provide the ultimate tool to address the role of MeCP2 in neuronal development. Thus, we plan to use biochemical, genetic, imaging, and molecular biology techniques to address two specific aims: 1) To characterize the molecular mechanisms underlying activity-dependent regulation of gene expression by MeCP2. 2) To test the in vivo contribution of activity dependent MeCP2 phosphorylation for nervous system function by generation of a MeCP2 S421A knock-in mouse model. We will initiate our aims during the mentored phase and I will carry on the characterization during the independent phase of this award. I plan to establish an independent research program focused on the biology of neurological diseases such as RTT and ASDs in the near future. It is our hope that the proposed experiments will provide a better understanding of MeCP2 function, give insight into the mechanisms of activity-dependent gene expression and neuronal development, and provide new opportunities for the development of therapeutic strategies to alleviate RTT pathology.