Activity-dependent regulation of neuromuscular junction formation

描述（由申请人提供）：突触发生受活动依赖性和独立机制的调节。突触发生的活动依赖性调节部分是由基因表达的变化介导的。因此，神经科学家的一个重要目标是了解突触活动如何被转导到基因组以影响突触形成的机制。神经肌肉连接（NMJ）是一个被充分研究的模型，用于识别和表征突触活动影响突触形成和调节基因表达的机制。尽管对NMJ形成的活性依赖控制已经研究了几十年，但对其潜在的分子机制知之甚少。我们最近发现了一个dach2依赖的信号转导级联，该级联有助于nAChR和MuSK基因的活性依赖表达。因此，该信号级联以及先前报道的HDAC9 （MITR）信号级联，也参与活性依赖的nAChR基因表达，代表了介导突触传递对NMJ形成影响的良好候选。在这项资助申请中，我们建议结合遗传学方法和细胞和分子生物学方法来研究Dach和MITR信号在神经诱导的肌肉去极化中调节NMJ形成和控制基因表达的作用。敲除动物将用于研究NMJ的发育，而神经支配和去神经支配的骨骼肌将用于研究神经诱导的、活动依赖的基因调控。具体而言，我们建议：1)评估Dach2和MITR在NMJ发展过程中的作用；2)检查HDAC4是否在肌肉神经支配下协调Dach2和MITR基因的抑制；3)确定Dach相互作用蛋白Six和Eya是否参与活性依赖性基因表达调控。本研究将确定肌肉活动在发育过程中调节突触形成的机制，并改变成人突触和肌肉功能。虽然这项研究是基础性的，但它可能为损伤、患病或老年个体提供增强突触形成、突触可塑性和肌肉功能的方法。公共卫生相关性：本拨款申请中的研究旨在了解肌肉活动如何向基因组发出信号，以调节神经肌肉发育、肌肉萎缩和肌肉基因表达。这些研究不仅将进一步加深我们对这些事件背后机制的理解，而且还可能为恢复神经肌肉通讯和改善损伤或疾病后的肌肉功能提供新的策略。

DESCRIPTION (provided by applicant): Synaptogenesis is regulated by both activity-dependent and independent mechanisms. Activity-dependent regulation of synaptogenesis is mediated, in part, by changes in gene expression. Therefore an important goal of neuroscientists is to understand the mechanisms by which synaptic activity is transduced to the genome to influence synapse formation. The neuromuscular junction (NMJ) is a well studied model for identifying and characterizing the mechanisms by which synaptic activity influences synapse formation and regulates gene expression. Although activity-dependent control of NMJ formation has been studied for decades, the underlying molecular mechanisms are poorly understood. We recently identified a Dach2-dependent signal transduction cascade that contributes to activity-dependent expression of nAChR and MuSK genes. Therefore, this signaling cascade along with the previously reported HDAC9 (MITR) signaling cascade, that also participates in activity-dependent nAChR gene expression, represent good candidates for mediating the effects of synaptic transmission on NMJ formation. In this grant application we propose to use a combination of genetic approaches and cell and molecular biological approaches to investigate the role Dach and MITR signaling play in regulating NMJ formation and controlling gene expression by nerve-induced muscle depolarization. Knockout animals will be used to study NMJ development, while innervated and denervated skeletal muscle will be used to study nerve-induced, activity-dependent gene regulation. Specifically, we propose to: 1) Evaluate the role Dach2 and MITR play during development of the NMJ; 2) Examine if HDAC4 coordinates Dach2 and MITR gene repression in response to muscle innervation; and 3) Determine if the Dach interacting proteins Six and Eya participate in activity-dependent regulation of gene expression. This research will identify mechanisms by which muscle activity regulates synapse formation during development and modifies synapse and muscle function in the adult. Although this research is of a basic nature, it may suggest ways of enhancing synapse formation, synaptic plasticity and muscle function in the injured, diseased or aged individual. PUBLIC HEALTH RELEVANCE: The studies in this grant application aim to understand how muscle activity signals to the genome to regulate neuromuscular development, muscle atrophy and muscle gene expression. These studies will not only further our understanding of the mechanisms underlying these events, but may also suggest novel strategies for restoring neuromuscular communication and improving muscle function following injury or disease.