MeCP2 Dependent Transcriptional Repression & Neurotransmission

描述（由申请人提供）：本提案的主要目的是进一步描述MeCP2，与Rett综合征（RTT）相关的基因，通过其作为转录抑制因子的功能在兴奋性神经传递中的作用。我们最近的研究表明，神经元中MeCP2的缺失导致兴奋性突触传递的改变，而不是抑制性突触传递。我们还证明了这些兴奋性传递（短期可塑性的一个组成部分）的缺陷是由于MeCP2作为转录抑制因子的作用。相反，我们最近发现MeCP2的过表达导致兴奋性突触传递的改变和突触抑制，这与MeCP2缺失后的结果相反。这一点很重要，因为如果MeCP2是突触功能的真正调节器，那么我们就可以预期MeCP2的双向变化会导致神经传递的相互改变。提出的研究将通过使用分子，细胞和电生理方法解决三个特定目标来补充和扩展我们以前的工作。首先，我们将进一步表征MeCP2短期可塑性的丧失，以更充分地了解其在神经元功能中的内源性作用。其次，我们将表征MeCP2在短期可塑性中的过表达，以研究MeCP2表达的改变如何影响突触传递。这一点很重要，因为最近的研究表明，MeCP2基因的重复可能是某些形式的智力迟钝和进行性神经症状的基础。最后，我们将阐明组蛋白去乙酰化酶（HDACs） 1和2在突触传递中的作用，它们是基因抑制的关键抑制因子，是MeCP2调控基因表达的多蛋白复合物的一部分。我们的假设是MeCP2表达的改变对突触功能有影响。本申请中提出的研究将通过进一步表征MeCP2表达的改变如何导致神经传递缺陷以及MeCP2复合物的HDAC成分如何参与这些过程来扩展我们的原始假设。这一信息很重要，因为它将开始提供一个框架，在这个框架中，探索突触改变可能是RTT各个方面的基础。公共卫生相关性：本项目中提出的实验代表了一项全面的努力，以解决MeCP2（与Rett综合征相关的基因）通过其作为转录抑制因子的功能在兴奋性神经传递中的作用。目前，缺乏对MeCP2在中枢突触短期突触可塑性中的作用的深入分析。在这个项目中，我们将通过互补的方法来研究MeCP2的缺失或MeCP2的过表达如何导致突触传递的改变。我们还将阐明组蛋白去乙酰化酶（HDACs） 1和2在突触传递中的作用，它们是基因抑制的关键抑制因子，是MeCP2调控基因表达的多蛋白复合物的一部分。从这些研究中获得的信息将为可能影响Rett综合征以及涉及MeCP2表达改变的相关疾病的突触机制提供新的见解。

DESCRIPTION (provided by applicant): The major objective of this proposal is to further delineate the role of MeCP2, the gene linked to Rett Syndrome (RTT), in excitatory neurotransmission through its function as a transcriptional repressor. We have recently shown that the loss of MeCP2 in neurons contributes to alterations in exicitatory, but not inhibitory, synaptic transmission. We also demonstrated that these deficits in excitatory transmission, a component of short term plasticity, appear due to MeCP2's role as a transcriptional repressor. Conversely we have recently found that overexpression of MeCP2 results in alterations in excitatory synaptic transmission and synaptic depression opposite to those obtained following the loss of MeCP2. This is important because if MeCP2 is a bona fide regulator of synaptic function then we would expect bidirectional changes in MeCP2 to result in reciprocal alterations in neurotransmission. The proposed studies will complement and extend our previous work by addressing three specific aims using molecular, cellular and electrophysiological methods. We will first, further characterize the loss of MeCP2 in short term plasticity to more fully discern its endogenous role in neuronal function. Second, we will characterize the overexpression of MeCP2 in short term plasticity to examine how alterations in MeCP2 expression effects synaptic transmission. This is important since recent studies have shown that duplication of the MeCP2 gene may underlie certain forms of mental retardation and progressive neurological symptoms. Lastly, we will elucidate the role of histone deacetylases (HDACs) 1 and 2, key repressors of gene repression that are part of a multiprotein complex with MeCP2 in regulating gene expression, on synaptic transmission. Our hypothesis is that alterations in MeCP2 expression contribute to effects on synaptic function. The studies proposed in this application will extend our original hypothesis by further characterizing how alterations in the expression of MeCP2 contributes to deficits in neurotransmission as well as how the HDAC components of the MeCP2 complex may be involved in these processes. This information is important because it will start to provide a framework in which to explore how synaptic alterations may underlie aspects of RTT. PUBLIC HEALTH RELEVANCE: The experiments proposed in this project represent a comprehensive effort to address the role of MeCP2, the gene linked to Rett Syndrome, in excitatory neurotransmission through its function as a transcriptional repressor. Currently, a thorough analysis of the role of MeCP2 in short-term synaptic plasticity in central synapses is lacking. In this project, we will examine via complementary approaches how the loss of MeCP2 or the overexpression of MeCP2 contributes to alterations in synaptic transmission. We will also elucidate the role of histone deacetylases (HDACs) 1 and 2, key repressors of gene repression that are part of a multiprotein complex with MeCP2 in regulating gene expression, on synaptic transmission. Information attained from these studies will provide new insight into the synaptic mechanisms that may be affected in Rett Syndrome as well as related disorders that involve alterations in MeCP2 expression.