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）内化膜组分和受体相关配体的机制。在配体解离后，大量受体通过“循环内体”返回质膜。虽然已知内体的酸性腔内pH值在配体与受体的解离及其降解中起重要作用，但我们对内体pH值循环调节的了解，特别是在神经元中，是有限的。我们研究的长期目标是确定内体pH值在神经元细胞中的生物学作用。直到最近，研究人员才开始意识到，在神经元细胞中，核内体的功能比在非神经元细胞中更多样化，蛋白质和脂质通过这些特化的核内体被分类到轴突和树突上。然而，内体多样性是如何在神经元细胞中建立的仍是未知的。我们假设神经元细胞含有比非神经元细胞更多的酸性内体，这为选择受体优先靶向轴突和树突提供了基础。因此，内体pH值可能为神经递质及其受体之间的神经通讯提供了新的机制。