Role of the S97N domain of Dig in synapse development

描述(由申请人提供)：本申请中提出的研究将主要在智利圣地亚哥的智利大学与Jimena Sierralta博士合作进行，作为NIH赠款RO1 NS42629的延伸。PI研究的长期目标是了解利用遗传方法在果蝇的谷氨酸能神经肌肉接头中组装突触的分子机制。这项研究中出现的一个重要发现是，PSD-95家族中含有PDZ的支架蛋白DLG基本上是正确定位一些突触蛋白所必需的。父母资助的中心目标是表征两个DLG相互作用的蛋白质，Scribble和GUK-Holder，在突触组装过程中的作用。以前对地高辛基因座的研究发现，突触和上皮细胞中都存在单一的转录物，即地高辛-A。然而，西拉尔塔博士最近的研究表明，来自Dig基因座的转录本存在广泛的替代处理。非常有趣的是，一组剪接变异体被上皮组织排除在外，并在神经系统中特异表达。此外，异构体的一个子集包含一个类似于哺乳动物SAP97的N-末端延伸，它调节SAP97的定位以及控制SAP97与其伙伴之间结合的分子内相互作用。这项合作研究的主要目标是研究这些新的剪接变体在突触形成和成熟的不同方面所起的作用。这项工作涉及包含$97N结构域的DLG异构体在突触发育过程中的表达，包含$97N结构域的DIG基因产物在突触发育过程中的选择性破坏，以及该结构域在DIG与其伙伴结合中的作用。我们预计，国外实验室的观察提供的新维度将极大地增强我们对突触形成过程中DLG的理解，从而增加在执行父母资助期间获得的知识。

DESCRIPTION (provided by applicant): The research proposed in this application will be primarily performed in Santiago, Chile at the Universidad de Chile in collaboration with Dr. Jimena Sierralta as an extension of NIH grant RO1 NS42629.The long-term goal of the PI's research is to understand the molecular mechanisms by which synapses are assembled using a genetic approach in the glutamatergic neuromuscular junction of Drosophila. An important finding emerging from this investigation is that a PDZ-containing scaffolding protein of the PSD-95 family, DLG, is essentially required to properly localize a number of synaptic proteins. The central aim of the parent grant is to characterize the role of two DLG interacting proteins, Scribble and GUK-holder, in the process of synapse assembly. Previous studies of the dig locus identified the presence of a single transcript, dig-A, which is present both in synapses and epithelial cells. However, recent studies by Dr. Sierralta demonstrate extensive alternative processing of transcripts originated from the dig locus. Very interestingly, a group of splice variants are excluded from epithelial tissue and are specifically expressed in the nervous system. Moreover, a subset of isoforms contains an N-terminal extension similar to mammalian SAP97, which regulates SAP97 localization as well as intramolecular interactions that control the binding between SAP97 and its partners. The main goal of the proposed collaborative research is to investigate the role of these novel splice variants in different aspects of synapse formation and maturation. The work involves the study of the expression of DLG isoforms containing the $97N domain during the development of synapses, the selective disruption of dig gene products containing the $97N domain during synapse development, and the study of the role of this domain in Dig binding to its partners. We envision that the novel dimension provided by the observations in the foreign lab will dramatically enhance our understanding of DLG during synapse formation, and therefore will increase the knowledge obtained during the execution of the parent grant.