Mechanism of dystroglycan function at inhibitory synapses.

项目摘要 肌营养不良聚糖是一种高度糖基化的跨膜受体，在多种组织中表达 包括肌肉和大脑。18个基因中至少一个的突变减少了肌营养不良蛋白聚糖 糖基化和功能，导致人类先天性肌营养不良症的异质组 （肌营养不良聚糖病），其特征在于肌肉无力、皮质畸形、认知障碍，以及 癫痫发作在脑内，肌营养不良蛋白聚糖由神经胶质和神经元高度表达。虽然肌营养不良聚糖已经被 广泛研究了其在皮质发育期间调节放射状神经胶质支架完整性的作用， 神经元肌营养不良蛋白聚糖的后续功能仍然难以捉摸。最近，一个令人惊讶的要求， 在CCK/CB 1 R+神经元间突触的形成和维持中，鉴定了神经元肌营养不良聚糖。 然而，对肌营养不良蛋白聚糖如何选择性地调节肌营养不良蛋白聚糖的形成和 缺乏CCK/CB 1 R+突触的维持。根据这些发现和我的初步数据，我将测试 在兴奋性神经元中表达的肌营养不良蛋白聚糖促进神经元的存活和形成的假说， CCK/CB 1 R+中间神经元及其突触以糖基化依赖的方式。 这个项目将阐明如何dystroglycan功能在抑制性突触使用组合 组织学、切片电生理学和成像方法在体内遗传模型和体外神经元 cultures.目的1验证突触前CCK/CB 1 R+中间神经元经历细胞程序化的假说， 在缺乏突触后肌营养不良蛋白聚糖的情况下死亡，以及肌营养不良蛋白聚糖是否是初始形成所必需的 或维持功能性突触。目的2将提供肌营养不良蛋白聚糖如何促进 通过定义肌营养不良蛋白聚糖介导的突触形成是否需要其 糖基化这些实验将提供关键的洞察力的基本机制，神经元 肌营养不良蛋白聚糖控制亚型特异性抑制性突触发育。这项研究还将提供线索， 肌营养不良症中特定神经症状的分子和细胞起源，最终有助于 为恢复肌营养不良蛋白聚糖糖基化和脑功能， 患者

Project Summary Dystroglycan is a heavily glycosylated transmembrane receptor expressed in a wide variety of tissues throughout development, including muscle and brain. Mutations in at least one of 18 genes reduce dystroglycan glycosylation and function, causing a heterogeneous group of human congenital muscular dystrophies (dystroglycanopathies) characterized by muscle weakness, cortical malformations, cognitive impairments, and seizures. Within the brain, dystroglycan is highly expressed by glia and neurons. While dystroglycan has been studied extensively for its role in regulating the integrity of the radial glial scaffold during cortical development, the subsequent function of neuronal dystroglycan has remained elusive. Recently, a surprising requirement for neuronal dystroglycan in the formation and maintenance of CCK/CB1R+ interneuron synapses was identified. However, a detailed mechanistic understanding of how dystroglycan selectively regulates the formation and maintenance of CCK/CB1R+ synapses is lacking. Based on these findings and my preliminary data, I will test the hypothesis that dystroglycan expressed in excitatory neurons promotes survival and formation of CCK/CB1R+ interneurons and their synapses in a glycosylation-dependent manner. This project will elucidate how dystroglycan functions at inhibitory synapses using a combination of histological, slice electrophysiology, and imaging approaches in both in vivo genetic models and in vitro neuronal cultures. Aim 1 will test the hypothesis that presynaptic CCK/CB1R+ interneurons undergo programmed cell death in the absence of postsynaptic dystroglycan, and whether dystroglycan is required for the initial formation or maintenance of functional synapses. Aim 2 will provide mechanistic insight into how dystroglycan promotes inhibitory synaptogenesis by defining whether dystroglycan-mediated synapse formation requires its glycosylation. These experiments will provide critical insight into the basic mechanisms by which neuronal dystroglycan controls subtype-specific inhibitory synapse development. This study will also provide clues about the molecular and cellular origins of specific neurological symptoms in dystroglycanopathy, ultimately helping to inform development of therapeutic strategies for restoring dystroglycan glycosylation and brain function in patients.