Role of AMPA Receptor Reverse Signaling in Synapse Stability

描述(申请人提供)：功能性神经元回路的建立依赖于过量突触的形成，然后消除不适当的连接。尽管突触前输入的稳定对功能电路的发展和维持至关重要，但调节突触前稳定性的信号尚不清楚。我们的初步研究表明，在皮层培养中突触的形成是高度动态的，涉及到在突触形成和消除的高速率背景下突触子集的稳定。在突触形成的高峰期，只有大约50%的假定突触在一小时内保持稳定。我们发现，突触前的稳定性与突触后AMPA的存在密切相关，但与NMDA受体的存在无关。我们已经确定LRRTM2是一种与GluR2相互作用的跨膜蛋白，影响突触的稳定性。根据我们的初步研究，我们假设GluR2-LRRTM2复合体作为逆行信号调节突触前的稳定性。目的1：确定GluR2受体的得失是否影响突触的稳定性，并确定介导这一作用的GluR2结构域。目的2：确定GluR2和LRRTM2的结构域，并确定LRRTM2被招募到突触部位的机制。目的3：确定GluR2-LRRTM2相互作用在调节突触前稳定性和突触功能中的作用。这些实验将为调节突触形成和稳定性的机制提供重要的见解。这些机制很可能在雷特综合征、自闭症和阿尔茨海默病等神经系统疾病中被破坏，这些疾病的特征是突触丢失，并可能提出治疗干预的方法。与公共健康相关：该项目的目标是了解在发育过程中调节大脑中突触连接形成的分子机制。一些儿童神经疾病，如自闭症、Rett综合征和X-连锁精神发育迟缓，其特征是突触连接缺陷。该项目的研究结果将指导人们更好地理解和制定针对这些疾病的治疗策略。

DESCRIPTION (provided by applicant): The establishment of functional neuronal circuits relies on the formation of excess synapses, followed by the elimination of inappropriate connections. Although the stabilization of presynaptic inputs is critical for the development and maintenance of functional circuits, the signals that regulate presynaptic stability are not known. Our preliminary studies suggest that synapse formation in cortical cultures is highly dynamic and involves the stabilization of a subset of synapses in a backdrop of a high rate of synapse formation and elimination. During the peak of synaptogenesis, only about 50% of putative synapses are stable over an hour. We have found that presynaptic stability is strongly correlated with the presence of postsynaptic AMPA but not NMDA receptors. We have identified LRRTM2 as a GluR2-interacting transmembrane protein that affects synapse stability. Based on our preliminary studies we hypothesize that a GluR2- LRRTM2 complex functions as a retrograde signal to regulate presynaptic stability. The specific aims of this proposal are: Aim 1: To determine whether gain or loss of GluR2 receptors affects synapse stability, and to identify the domains of GluR2 that mediate this effect Aim 2: To identify the domains of GluR2 and LRRTM2 that mediate their interaction and to identify the mechanism by which LRRTM2 is recruited to synaptic sites Aim 3: To determine the role of GluR2-LRRTM2 interactions in regulating presynaptic stability and synaptic function These experiments will provide important insights into the mechanisms that regulate synase formation and stability. These mechanisms are likely to be disrupted in neurological diisorders such as Rett Syndrome, Autism, and Alzheimer's disease that are characterized by loss of synapses and may suggest approaches for therapeutic intervention. PUBLIC HEALTH RELEVANCE: The goal of this project is to understand the molecular mechanisms that regulate the formation of synaptic connections in the brain during development. Several childhood neurological disorders, such as Autism, Rett Syndrome, and X-linked mental retardation are characterized by defects in synaptic connectivity. The findings of this project should guide efforts to better understand and develop therapeutic strategies for these disorders.