Endosomal pH regulation in neurons: Roles of Na+/H+ exchangers

神经元内体 pH 调节：Na /H 交换器的作用

• 批准号: RGPIN-2015-06790
• 负责人: Numata, Masayuki
• 金额: $ 2.77万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=614367
• 关键词: Endosomal; pH; regulation; neurons; Roles

Endocytosis is a mechanism that internalizes membrane components and receptor-associated ligands through "endosomes", membrane-bound organelles. Upon dissociation of ligands, a large population of receptors returns to the plasma membrane via "recycling endosomes". While it is known that the acidic luminal pH of endosomes plays important roles in ligand-dissociation from the receptor and its degradation, our knowledge of recycling endosomal pH regulation, especially in neurons, is limited. The long-term goal of our research is to define biological roles of endosomal pH in neuronal cells. It is only very recently that researchers have begun to realize that endosomes are functionally more diverse in neurons than in non-neuronal cells, and proteins and lipids are sorted to axons and dendrites through those specialized endosomes. However, how the endosomal diversity is established in neuronal cells remains unknown. We hypothesize that neurons contain more acidic endosomes than non-neuronal cells, which provides a basis for preferential targeting of selected receptors to axons and dendrites. Thus, endosomal pH may add a new mechanistic insight into neuronal communication through the neurotransmitter and its receptor. We are going to investigate biological roles of endosomal pH in neurons by using two complementary approaches, one primarily biochemical, the second at the level of the whole organism. As Obj. 1, we will examine the role of endosomal pH in neuronal signaling and receptor targeting that are required for neuronal differentiation. Rat primary cultured neurons will be used for biochemical analyses already used in our laboratory with some modifications. As Obj. 2, we will explore the impact of pH changes in neuronal recycling endosomes on animal behavior using knock-out strains of fruit flies. Fruit flies are used because of the availability of powerful genetic techniques and sensitive behavioral tests. The physiological significance of biochemical interactions of endosomal pH-regulators and their binding partners will be addressed. We anticipate that our research will substantially advance basic understanding of endosomal function in neurons, with general applicability across cognitive science. Our experience in the field, the strong collaborative environment at UBC, access to outstanding trainees, and truly exciting preliminary results uniquely enable us to carry out our research program successfully. I am confident that through this research we will contribute to the Canadian society both through the acquisition of critical base knowledge as well as by training skilled and highly motivated future scientists through our program. The outcome of our research will be published in peer reviewed journals and presented at international conferences.

内吞作用是一种通过“内体”（膜结合细胞器）内化膜成分和受体相关配体的机制。配体解离后，大量受体通过“回收内体”返回质膜。虽然众所周知，内体的酸性管腔 pH 在配体从受体解离及其降解中发挥着重要作用，但我们对内体 pH 调节（尤其是神经元中）的循环利用的了解有限。我们研究的长期目标是确定神经元细胞内体 pH 的生物学作用。直到最近，研究人员才开始意识到神经元中的内体比非神经元细胞的功能更加多样化，并且蛋白质和脂质通过这些特化的内体被分类到轴突和树突。然而，神经元细胞中内体多样性是如何建立的仍然未知。我们假设神经元比非神经元细胞含有更多的酸性内体，这为选择性受体优先靶向轴突和树突提供了基础。因此，内体 pH 值可能会为通过神经递质及其受体进行神经元通讯提供新的机制见解。 我们将通过使用两种互补的方法来研究内体 pH 在神经元中的生物学作用，一种主要是生物化学的，第二种是在整个生物体水平上的。作为对象。 1，我们将检查内体 pH 在神经元分化所需的神经元信号传导和受体靶向中的作用。大鼠原代培养的神经元将用于我们实验室已使用的生化分析，并进行一些修改。作为对象。 2，我们将利用果蝇基因敲除品系探讨神经元回收内体中 pH 值的变化对动物行为的影响。使用果蝇是因为具有强大的遗传技术和敏感的行为测试。将讨论内体 pH 调节剂及其结合配偶体的生化相互作用的生理意义。我们预计我们的研究将极大地促进对神经元内体功能的基本理解，并具有整个认知科学的普遍适用性。我们在该领域的经验、UBC 强大的协作环境、接触优秀学员的机会以及真正令人兴奋的初步结果使我们能够成功地开展我们的研究项目。我相信，通过这项研究，我们将通过获取关键基础知识以及通过我们的项目培训熟练且积极主动的未来科学家，为加拿大社会做出贡献。我们的研究成果将发表在同行评审期刊上并在国际会议上展示。