ZINC TRANSPORT IN THE HUMAN BRAIN

本研究项目的长期目标是了解在人类中枢神经系统中促进神经元和胶质细胞锌离子稳态的细胞过程的相互作用。此外，我们将阐明发生在神经退行性疾病（如阿尔茨海默病）中的细胞锌离子稳态变化的潜在机制。这项试点拨款申请提出的实验将提供急需的关于人类大脑质膜锌离子流入和流出机制的新信息。此外，我们将确定与阿尔茨海默病病理相关的质膜锌转运的任何变化。然后，这些数据将形成后续RO1应用程序的基础，专注于实现我们的长期目标。该实验室发表的研究提供了令人信服的证据，证明从大鼠脑分离的质膜囊泡具有强大的锌转运活性。结果表明锌的可逆运输受ph值的高度影响。这些结果导致了以下工作假设，它形成了拟议研究的概念框架。锌离子转运体存在于质膜中，介导锌的内流和外排途径（即，转运体是自由可逆的）。输运机制可能涉及质子的反端口。这种锌离子转运体存在于人脑中，其活性可能在阿尔茨海默病等神经退行性疾病中发生改变。通过对人脑质膜囊泡中的锌通量进行彻底的动力学分析，我们将找到以下问题的答案，这些问题将检验上述假设的有效性。1. 锌转运体存在于人脑中吗？2. 锌的转运机制是什么？3. 是否存在高亲和力和低亲和力的锌转运体？4. 人脑中锌含量高的主要区域（如海马体）是否具有较高的锌运输活性？5. 阿尔茨海默病是否改变了人脑中的锌转运蛋白活性？

The long term goals of this research project are to understand the interplay of cellular processes contributing to neuronal and glial cell zinc ion homeostasis in the human central nervous system. In addition we will elucidate the underlying mechanisms of any changes in cellular zinc ion homeostasis that occur in neurodegenerative disorders such as Alzheimer's disease. This pilot grant application proposes experiments that will provide much needed new information on the mechanism of plasma membrane zinc ion influx and efflux in the human brain. Further, we will identify any changes in plasma membrane zinc transport that are associated with Alzheimer's disease pathology. These data will then form the basis of a subsequent RO1 application focused towards accomplishing our long term goals. Published studies from this laboratory have provided convincing evidence of a robust zinc transport activity associated with plasma membrane vesicles isolated from rat brain. The results point to a reversible transport of zinc which is highly influenced by pH. These results have led to the following working hypothesis, which forms the conceptual framework for the proposed research. A zinc ion transporter exists in the plasma membrane that mediates both influx and efflux pathways for zinc (i.e., the transporter is freely reversible). The transport mechanism may involve antiport of protons. This zinc ion transporter is present in human brain and its activity may be altered in neurodegenerative disorders such as Alzheimer's Disease. By performing a thorough kinetic analysis of zinc fluxes in human brain plasma membrane vesicles we will find the answers to the following questions, which test the validity of the above hypothesis. 1. Is the zinc transporter present in human brain? 2. What is the mechanism of zinc transport? 3. Do high affinity and low affinity zinc transporters exist? 4. Do major areas of human brain which contain high levels of zinc (e.g., hippocampus), have higher levels of zinc transport activity? 5. Is zinc transporter activity in human brain altered in Alzheimer's Disease?