Experience-dependent regulation of the Fragile X gene

描述（由申请人提供）：神经科学的一个基本问题是理解短暂的经历如何转化为突触结构和功效的稳定变化。这种持久的突触修饰的产生需要新的蛋白质合成，而这反过来又在转录和翻译水平上受到调节。此外，神经元的转录谱是其发育阶段（如关键期）及其激活历史的功能。因此，揭示长期可塑性机制的一个主要挑战是将发育时间和经验诱导的神经活动与在突触可塑性中起关键作用的已识别分子的调节联系起来。脆性X染色体综合征（FXS）为这个问题的核心提供了一个入口。FXS影响约1:4000男孩，由Fmr1启动子的三联体重复扩增和超甲基化引起，导致基因沉默。Fmr1基因的蛋白产物FMRP在调节蛋白质合成依赖的突触可塑性中起核心作用。我们的实验室已经建立了体内和细胞培养系统来研究Fmr1的转录和表达。我们发现Fmr1转录本在发育和成年嗅球中非常丰富，并受嗅觉经验的双向调节。初步的体内和体外培养研究已经为调控Fmr1转录的两种分子机制提供了证据：转录因子AP-2a和Fmr1基因调控区域的选择性、发育调控的表观遗传修饰。在本研究中，我们将利用嗅觉系统结合遗传和细胞培养模型来阐明完整中枢神经系统中Fmr1基因调控的分子逻辑。

DESCRIPTION (provided by applicant): A fundamental problem in neuroscience is understanding how ephemeral episodes of experience are transformed into stable changes in synaptic architecture and efficacy. The creation of such long-lasting synaptic modifications requires new protein synthesis, which in turn is regulated at both transcriptional and translational levels. Moreover, the transcriptional profile of the neuron is a function of its developmental stage - e.g. critical period - and its history of activation. A major challenge in unraveling the mechanisms of long term plasticity then is to relate both developmental timing and experience-induced neural activity to the regulation of identified molecules that play key roles in synaptic plasticity. Fragile X Syndrome (FXS) offers a portal to the heart of this problem. FXS affects about 1:4000 boys and is caused by a triplet repeat expansion and hypermethylation of the Fmr1 promoter, leading to gene silencing. The protein product of the Fmr1 gene, FMRP, plays a central role in regulating protein synthesis-dependent synaptic plasticity. Our laboratory has established in vivo and cell culture systems for the study of Fmr1 transcription and expression. We find that Fmr1 transcripts are highly abundant in the developing and adult olfactory bulb and are bi-directionally regulated by olfactory experience. Preliminary in vivo and ce|l culture studies have provided evidence for two molecular mechanisms that regulate Fmr1 transcription: the transcription factor AP-2a and the selective, developmentally-regulated epigenetic modification of the Fmr1 gene regulatory regions. In the proposed studies we will use the olfactory system together with genetic and cell culture models to elucidate the molecular logic of Fmr1 gene regulation in the intact CNS.