Regulation of the Synaptic Localization of the nAChR

nAChR 突触定位的调节

• 批准号: 6815922
• 负责人: MICHAEL J FERNS
• 金额: $ 30.67万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6815922
• 关键词: acetylcholine; agrin; binding sites; cholinergic receptors; developmental neurobiology; gene targeting; genetically modified animals; histology; laboratory mouse; neurogenesis; neuromuscular disorder; neuromuscular junction; nicotinic receptors; phosphorylation; protein localization; protein protein interaction; protein sequence; protein structure function; receptor binding; synapses

DESCRIPTION (provided by applicant): Synapses are highly specialized for efficient synaptic transmission, with the transmitter release sites in the presynaptic nerve terminal being aligned with postsynaptic concentrations of the neurotransmitter receptor. At the developing neuromuscular junction, a nerve-derived factor called agrin directs the postsynaptic localization of the acetylcholine receptor, and our goal is to understand the molecular mechanisms that underlie agrin's action. Specifically, we will test the hypothesis that agrin regulates AChR localization by inducing phosphorylation of the AChR and altering its association with the intracellular scaffolding protein, rapsyn. We have the following specific aims: (1) To define the role of agrin-induced phosphoryation of the beta subunit in AChR localization. We will generate transgenic mice with a beta subunit lacking the phosphorylation site, and then determine whether this mutation impairs the synaptic localization of the AChR. We will also determine whether phosphorylation specifically regulates the anchoring, clustering, and/or stabilization of the receptor in the postsynaptic membrane. (2) To define the molecular mechanism of rapsyn-mediated AChR localization. Here, we will define rapsyn's binding site(s) on the AChR and determine whether binding is regulated by agrin. Moreover, we will investigate how agrin-induced changes in rapsyn/AChR association mediate receptor localization. This work is directly relevant to neuromuscular disorders such as congenital and autoimmune myasthenic syndromes, where there are severe deficiencies in AChR levels at the synapse, leading to impaired synaptic function and debilitating muscle weakness. Our work will help define the mechanisms involved in receptor localization and may suggest strategies to stabilize its localization in patients with myasthenic syndromes or other forms of neuromuscular disease.

描述（由申请人提供）：突触对于有效的突触传递是高度专门化的，突触前神经末梢中的递质释放位点与神经递质受体的突触后浓度对齐。在发育中的神经肌肉接头处，一种称为 agrin 的神经源性因子指导乙酰胆碱受体的突触后定位，我们的目标是了解 agrin 作用的分子机制。具体来说，我们将测试 agrin 通过诱导 AChR 磷酸化并改变其与细胞内支架蛋白 rapsyn 的关联来调节 AChR 定位的假设。我们有以下具体目标：（1）明确集聚蛋白诱导的β亚基磷酸化在AChR定位中的作用。我们将产生缺乏磷酸化位点的β亚基的转基因小鼠，然后确定这种突变是否损害AChR的突触定位。我们还将确定磷酸化是否特异性调节突触后膜中受体的锚定、聚集和/或稳定。 (2)明确rapsyn介导的AChR定位的分子机制。在这里，我们将定义 rapsyn 在 AChR 上的结合位点，并确定结合是否受集聚蛋白调节。此外，我们将研究 agrin 诱导的 rapsyn/AChR 关联变化如何介导受体定位。这项工作与先天性和自身免疫性肌无力综合征等神经肌肉疾病直接相关，这些疾病中突触的 AChR 水平严重缺乏，导致突触功能受损和肌肉无力。我们的工作将有助于定义受体定位所涉及的机制，并可能提出在肌无力综合征或其他形式的神经肌肉疾病患者中稳定其定位的策略。