MeCP2 Dependent Transcriptional Repression & Neurotransmission

描述(由申请人提供)：这项建议的主要目标是进一步描述MeCP2，与Rett综合征(RTT)相关的基因，通过其转录抑制因子的功能在兴奋性神经传递中的作用。我们最近发现，神经元中MeCP2的丢失有助于兴奋性突触传递的改变，但不会导致抑制性突触传递的改变。我们还证明，兴奋性传递中的这些缺陷是由于MeCP2的S作为转录抑制因子而出现的，兴奋性传递是短期可塑性的一个组成部分。相反，我们最近发现，MeCP2的过度表达导致兴奋性突触传递和突触抑制的变化，与MeCP2丢失后的变化相反。这一点很重要，因为如果MeCP2是突触功能的真正调节者，那么我们预计MeCP2的双向变化将导致神经传递的互惠变化。拟议的研究将补充和扩展我们之前的工作，通过使用分子、细胞和电生理方法解决三个特定目标。首先，我们将进一步描述MeCP2在短期可塑性中的缺失，以更充分地了解其在神经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度表达，以检测MeCP2表达的变化如何影响突触传递。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精神发育迟滞和进行性神经症状的基础。最后，我们将阐明组蛋白脱乙酰酶(HDACs)1和2，这两个关键的基因抑制因子，是与MeCP2形成的多蛋白复合体的一部分，在调节基因表达的过程中，在突触传递中扮演着重要的角色。我们的假设是，MeCP2表达的改变有助于影响突触功能。本申请中提出的研究将扩展我们最初的假设，进一步表征MeCP2表达的变化如何导致神经传递障碍，以及MeCP2复合体的HDAC组件如何参与这些过程。这一信息很重要，因为它将开始提供一个框架，在其中探索突触变化如何可能成为RTT的各个方面的基础。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的作用，MeCP2是与Rett综合征有关的基因，通过其转录抑制因子的功能在兴奋性神经传递中发挥作用。目前，对MeCP2在中枢突触的短期突触可塑性中的作用缺乏深入的分析。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的过度表达如何导致突触传递的改变。我们还将阐明组蛋白脱乙酰酶(HDACs)1和2在突触传递中的作用。组蛋白脱乙酰酶1和2是基因抑制的关键抑制因子，是与MeCP2调节基因表达的多蛋白复合体的一部分。从这些研究中获得的信息将为研究Rett综合征中可能受到影响的突触机制以及涉及MeCP2表达变化的相关疾病提供新的见解。

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.