Dystroglycan regulates cerebellar synapse function

项目摘要 营养不良多糖是一种由跨膜β亚基和非共价键组成的支架分子。 结合的胞外α亚基。阿尔法亚单位经历了大量的糖基化，它是通过这些 营养不良的糖链与细胞外结合伙伴形成蛋白质-碳水化合物的相互作用。一个 不能正确地糖基化营养不良会导致一种称为营养不良的肌营养不良症。 糖代谢不良症中出现的肌肉缺陷通常伴有神经缺陷。而当 营养不良多糖在肌肉完整性中的作用已经被很好地描述，它在疾病的神经学方面的作用 仍然没有得到充分的研究。已知神经上皮细胞中的营养不良多糖是正常迁移所必需的。 发育中的神经元，但营养不良蛋白聚糖在整个生命过程中保持在高水平，这表明除了 发展。已有研究表明，神经性营养不良糖链与某些抑制性标志物共定位。 突触并可以与Neurexins相互作用，Neurexins是突触前的一类支架分子，在 大脑。综上所述，这暗示了营养不良糖链在抑制因子亚群的形成中的潜在作用。 突触，充当突触后的支架分子。 最近的研究表明，海马区锥体神经元中的营养不良多糖是 抑制篮子突触的一个子集的功能，但其他大脑区域仍未被探索。这项研究将 重点关注小脑中的抑制性突触，那里的营养不良多糖在 浦肯野神经元。拟议的实验将利用小鼠的遗传学、成像学和切片生理学来解剖。 营养不良糖蛋白促进突触形成和/或维持抑制性突触的机制 在小脑皮层。目标1将识别存在营养不良糖链的突触子集，并将描述 营养不良多糖在这些突触功能中的重要性。然后，目标2将试图剖析 并将测试基因治疗的可行性，以挽救 观察到突触表型。目的3将研究营养不良多糖的不同结构域在突触中的作用 功能：来自β亚基C-尾的细胞内信号及与细胞外结合的相互作用 通过阿尔法亚单位的糖基化来配对。这项工作将是最早探索体内功能的工作之一。 营养不良多糖在大脑突触中的作用。此外，这些实验将提供对 关于营养不良糖链缺陷如何导致人类糖尿病患者认知障碍的问题 这将有助于开发治疗此类认知缺陷的基因疗法。

Project Summary Dystroglycan is a scaffolding molecule composed of a transmembrane beta subunit and a non-covalently bonded extracellular alpha subunit. The alpha subunit undergoes heavy glycosylation and it is through these glycan chains that Dystroglycan forms protein-carbohydrate interactions with extracellular binding partners. A failure to properly glycosylate Dystroglycan results in a form of muscular dystrophy termed dystroglycanopathy. The muscular defects seen in dystroglycanopathies are often accompanied by neurological defects. While the role of Dystroglycan in muscle integrity has been well described, its role in the neurological aspects of the disease remains understudied. It is known that Dystroglycan in neuroepithelial cells is necessary for the proper migration of neurons during development, but Dystroglycan remains at high levels throughout life, suggesting a role beyond development. It has been shown that neuronal Dystroglycan co-localizes with certain markers of inhibitory synapses and can interact with neurexins, a well described class of presynaptic scaffolding molecules in the brain. Together, this suggests a potential role for Dystroglycan in the development of a subset of inhibitory synapses, acting as a postsynaptic scaffolding molecule. Recent work has shown that Dystroglycan in pyramidal neurons of the hippocampus is required for the function of a subset of inhibitory basket synapses, but other brain regions remain unexplored. This study will focus on inhibitory synapses in the cerebellum, where Dystroglycan is present at particularly high levels in Purkinje neurons. The proposed experiments will utilize mouse genetics, imaging, and slice physiology to dissect the mechanism by which Dystroglycan promotes synapse formation and/or maintenance of inhibitory synapses in cerebellar cortex. Aim 1 will identify the subset of synapses at which Dystroglycan is present and will describe the importance of Dystroglycan in the function of these synapses. Aim 2 will then seek to dissect the role of Dystroglycan in synapse formation and maintenance and will test the feasibility of gene therapy to rescue the observed synaptic phenotype. Aim 3 will investigate the roles of the various domains of Dystroglycan in synapse function: intracellular signaling from the C-tail of the beta subunit and the interaction with extracellular binding partners via glycosylation of the alpha subunit. This work will be among the first to explore the in vivo functional role of Dystroglycan at synapses in the brain. Furthermore, these experiments will provide understanding with regards to how defects in Dystroglycan results in cognitive deficits in human patients suffering from dystroglycanopathies and will aid in the development of gene therapies to treat such cognitive defects.