Regulation of Neuronal Synaptic Components

描述（由申请人提供）：烟碱乙酰胆碱受体（nAChRs）在关键的神经元间和中枢感觉器官突触中起作用。它们的激活介导兴奋性传递，加强尼古丁成瘾，增加记忆形成，并调节听觉的敏感性。胆碱能突触的功能障碍与发育和神经退行性疾病有关，如阿尔茨海默病、精神分裂症、夜间额叶癫痫和自身免疫性自主神经病变。尽管尼古丁突触在生理上具有重要意义，但在发育过程中，人们对其组装的分子机制知之甚少。此外，正确的突触形成和功能需要突触前和突触后特化的精确对齐，但其潜在机制尚不清楚。我们最近的研究发现，大肠腺瘤性息肉病（APC）是体内神经元间胆碱能突触组装的关键分子。我们发现APC对于将a3-nAChR定位到突触后位点至关重要，从而确定APC是第一个在nAChR靶向神经元突触中起作用的非受体蛋白。我们提出APC具有两个关键的突触组织功能：(1)指导nAChR转运到突触后位点和/或稳定（Aim1）；(2)通过锚定nAChR积累位点的逆行信号复合物（Aim2）来指导突触前和突触后特化的对齐。此外，我们假设APC与三种基本的突触后组分：微管加末端结合蛋白-1 （EB1）、β -连环蛋白和突触后密度蛋白-93 （PSD-93）的相互作用介导了突触形成的这些基本方面。我们将使用功能丧失和功能获得策略来测试这些APC相互作用和结合伙伴在体内组织胆碱能突触中的具体作用。我们将测试APC在两种不同的尼古丁制剂中的作用：在内耳感觉毛细胞上含有a3- nachr的外周睫状神经节神经元突触和含有a9- nachr的中枢传出耳蜗突触。实验将使用遗传、分子、形态、生化和功能方法。这些研究将为指导胆碱能突触组装和功能的分子相互作用提供重要的新见解。进一步，研究将确定周围神经元和中枢感觉烟碱突触之间是否有共同的组织机制。

DESCRIPTION (provided by applicant): Nicotinic acetylcholine receptors (nAChRs) function at key interneuronal and central sensory organ synapses. Their activation mediates excitatory transmission, reinforces nicotine addiction, increases memory formation, and regulates the sensitivity of hearing. Malfunction of cholinergic synapses has been implicated in developmental and neurodegenerative disorders such as Alzheimer's disease, schizophrenia, nocturnal frontal lobe epilepsy, and autoimmune autonomic neuropathies. Despite the physiological importance of nicotinic synapses, little is known about the molecular mechanisms that direct their assembly during development. Further, proper synapse formation and function require precise alignment of pre- and postsynaptic specializations, but the underlying mechanisms are poorly understood. Our recent studies identify adenomatous polyposis coli (APC) as a key molecular player in interneuronal cholinergic synapse assembly in vivo. We show that APC is essential for localizing a3-nAChRs to postsynaptic sites, and thereby identify APC as the first non-receptor protein to function in nAChR targeting to neuronal synapses. We propose that APC has two key synapse organizing functions: (1) directing nAChR transport to and/or stabilization at postsynaptic sites (Aim1) and (2) directing the alignment of pre- and postsynaptic specializations by anchoring retrograde signaling complexes at sites of nAChR accumulation (Aim2). Further, we posit that APC'S interactions with three essential postsynaptic components: microtubule plus end binding protein-1 (EB1), beta-catenin and postsynaptic density protein-93 (PSD-93) mediate these essential aspects of synapse formation. We will use loss-of-function and gain-of-function strategies to test the specific roles of these APC interactions and binding partners in organizing cholinergic synapses in vivo. We will test APC'S role at two different nicotinic preparations: a3-nAChR-containing peripheral ciliary ganglion neuronal synapses and a9-nAChR-containing central efferent olivocochlear synapses on sensory hair cells of the inner ear. The experiments will use genetic, molecular, morphological, biochemical and functional approaches. The studies will provide important new insights into molecular interactions that direct the assembly and function of cholinergic synapses. Further, the studies will determine whether the organizational mechanisms are shared between peripheral neuron and central sensory nicotinic synapses.