The control of neural transmission by glycosylation

描述(由申请人提供)：我们的研究集中在糖蛋白唾液酸化神经功能的分子、细胞和系统机制上。虽然大脑是人体中最显著的唾液酸化器官，最近的研究发现唾液酸化缺陷与多种神经系统疾病有关，但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、多效性和冗余性的增加以及现有遗传方法的局限性显著阻碍了对绝大多数复杂脊椎动物神经系统中唾液酸化的研究。因此，一个合适的模型系统将是这一领域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模式生物来研究N-连锁唾液酸化的神经功能。果蝇唾液酸转移酶DSiaT是果蝇体内唯一的唾液酸转移酶。这种酶与人类同行高度同源，后者也与DSiaT有几个共同的功能特性，包括相似的受体特异性和在大脑中的表达上调。我们最近的实验表明，果蝇唾液酸化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连接的发展。唾液酸化异常会导致果蝇显著的神经表型，包括温度敏感型瘫痪，运动障碍，以及显著缩短的寿命。我们的实验表明，一个简单的N-连接的糖蛋白唾液酸化在调节神经活动中起着显著的作用，这为糖基化参与神经系统调节建立了一个新的范式。这种新颖的、神经系统特有的N-连接唾液酸聚糖的功能在苍蝇和人类之间具有潜在的保守性。本项目将扩展我们以前的研究，并将研究(I)唾液酸化在果蝇神经功能中的潜在细胞机制，(Ii)唾液酸化介导的神经兴奋性控制的分子机制，以及(Iii)唾液酸化在神经可塑性中的作用。我们将使用多学科策略，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，详尽描述的神经发育，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，以及用于多糖分析的新技术。这个项目将阐明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。我们的研究还将建立果蝇作为一个通用的模型系统，用于未来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.