The control of neural transmission by glycosylation

描述（由申请人提供）：我们的研究重点是糖蛋白唾液酸化神经功能的分子，细胞和系统机制。虽然大脑是人体中唾液酸化最突出的器官，并且最近的研究表明唾液酸化缺陷与多种神经系统疾病有关，但对这种重要类型的糖基化在神经系统中的功能仍然知之甚少。糖基化的复杂性、增加的多效性和冗余性以及可用遗传方法的局限性显著阻碍了对极其复杂的脊椎动物神经系统中唾液酸化的研究。因此，一个适当的模型系统将是在这一领域进行更有效和更快研究的重要工具。在这里，我们建议使用果蝇作为一个模式生物调查的神经功能的N-连接唾液酸化。我们以前的特点是果蝇唾液酸转移酶，DSiaT，一个唯一的唾液酸转移酶在果蝇。这种酶与其人类对应物高度同源，其也与DSiaT共享几种功能特性，包括类似的受体特异性和在大脑中的表达升高。我们最近的实验表明，唾液酸化在果蝇中的功能仅限于神经系统。我们发现唾液酸化调节神经传递和神经肌肉接头的发育。异常唾液酸化导致果蝇的神经系统表现型显著，包括温度敏感性麻痹、运动缺陷和寿命显著缩短。我们的实验表明，一个简单的N-连接糖蛋白唾液酸化在调节神经活动中起着重要作用，这建立了一个新的范式糖基化参与神经系统的调节。N-连接唾液酸化聚糖的这种新的神经系统特异性功能在果蝇和人类之间可能是保守的。目前的项目将扩展我们以前的研究，并将调查（i）在果蝇唾液酸化的神经功能的细胞机制，（ii）唾液酸化介导的神经兴奋性控制的分子机制，和（iii）唾液酸化在神经可塑性的作用。我们将采用多学科策略，结合果蝇模型系统的优势，包括其对遗传操作的特殊适应性，详尽的神经发育特征，唾液酸化基因的低冗余和多效性，以及成熟的电生理和行为方法，细胞培养和生化技术，以及聚糖分析的新技术。该项目将揭示神经调节和发育的关键进化保守原则，这可能对生物医学研究和相关治疗策略有用。我们的研究也将建立果蝇作为一个多功能的模型系统，为未来的研究糖基化在神经系统中的作用。

DESCRIPTION (provided by applicant): Our research focuses on the molecular, cellular, and systemic mechanisms underlying the neural functions of glycoprotein sialylation. Although the brain is the organ with the most prominent sialylation in human body, and recent studies implicated sialylation defects in several neurological diseases, the functions of this important type of glycosylation in the nervous system are still poorly understood. The intricacies of glycosylation, increased pleiotropy and redundancy, and limitations of available genetic approaches significantly hinder the research on sialylation in the overwhelmingly complex vertebrate nervous system. Thus, a suitable model system would be an important tool for more efficient and accelerated studies in this area. Here we propose to use Drosophila as a model organism to investigate the neural functions of N-linked sialylation. We previously characterized Drosophila sialyltransferase, DSiaT, a sole sialyltransferase in Drosophila. This enzyme is highly homologous to its human counterpart which also shares with DSiaT several functional properties, including similar acceptor specificity and an elevated expression in the brain. Our recent experiments revealed that the function of sialylation in Drosophila is limited to the nervous system. We found that sialylation regulates neural transmission and the development of neuromuscular junctions. Abnormal sialylation results in Drosophila in prominent neurological phenotypes, including temperature-sensitive paralysis, defects in locomotion, and a significantly shortened life span. Our experiments indicated that a simple N-linked glycoprotein sialylation plays a prominent role in modulating neural activity, which establishes a new paradigm of the involvement of glycosylation in the nervous system regulation. This novel, nervous system-specific function of N-linked sialylated glycans is potentially conserved between flies and humans. The current project will extend our previous research and will investigate (i) the cellular mechanisms underlying the neural function of sialylation in Drosophila, (ii) the molecular mechanisms of sialylation-mediated control of neural excitability, and (iii) the role of sialylation in neural plasticity. We will use a multidisciplinary strategy, combining the advantages of Drosophila model system, including its exceptional amenability to genetic manipulations, exhaustively characterized neural development, low redundancy and pleiotropy of sialylation genes, with well-established electrophysiological and behavioral approaches, cell culture and biochemical techniques, as well as novel technologies for glycan analyses. This project will shed light on the crucial evolutionarily conserved principles of neural regulation and development, which could be useful for biomedical research and relevant therapeutic strategies. Our research will also establish Drosophila as a versatile model system for future studies of the role of glycosylation in the nervous system.