DOPAMINE AND VESICULAR MONOAMINE TRANSPORTERS IN AGING

衰老过程中的多巴胺和囊泡单胺转运蛋白

• 批准号: 6957283
• 负责人: SAMMANDA RAMAMOORTHY
• 金额: $ 11.08万
• 依托单位: MEDICAL UNIVERSITY OF SOUTH CAROLINA
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-15 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6957283
• 关键词: Parkinson' s disease; aging; alpha synuclein; dopamine; dopamine transporter; gene environment interaction; gene expression; genetically modified animals; laboratory mouse; membrane transport proteins; methamphetamine; neural degeneration; neural transmission; neurotoxicology; phosphorylation; protein localization; protein structure function; psychomotor function

The development of motor and cognitive dysfunction during aging may be, in part associated with perturbations of central dopamine (DA) neurotransmission. At the molecular level, DA signaling is dynamically regulated by a diverse set of macromolecules including biosynthetic enzymes, degradative enzymes, secretory proteins, ion channels, pre- and post synaptic receptors and transporters. Various abnormalities in DA function have been postulated as causes of various types of neurodegenerative diseases, psychopathology and drug addiction. Several neuronal factors such as neurotrophic factors support development and neuroplasticity of DA neurons. Alterations or any compromised expression and regulation of these molecules may leads to age-related vulnerability of DA neurons. The plasma membrane dopamine transporter (DAT) and vesicular monoamine transporter (VMAT2) are essential for normal DA neurotransmission. DAT terminates the action of DA and maintain the extracellular levels of DA, whereas VMAT2 loads cytoplasmic DA into to vesicles and subsequent vesicular DA release as well as maintain intracellular cytoplasmic DA levels. High concentrations of DA and/or DA-metabolites in either intracellular cytoplasmic or elevated extracellular DA are documented to be toxic to striatal presynaptic dopaminergic terminals. Thus perturbation of the tightly regulated balance of these two transporters function may predispose the neurons to damage by variety of insults, such as growth factor deficiency or exposure to environmental toxins at different levels of life-span. While changes in DAT mRNAs and binding sites have been implicated in aging and Parkinson's disease, there are no studies investigating relevant alterations in transporter function, regulation and sub-cellular distribution in pre-synaptic DA terminals that are associated with normal aging. The central goal of this project is to comprehend the neuroadaptive changes in DAT and VMAT2 functional regulation during aging and test the hypothesis that the expression of DAT and VMAT2 can predict the selective vulnerability of DA terminals. Combining state-of art biochemical and molecular approaches with the animal model outlined in animal core, this project proposes to determine systematically (a) the progression of changes in the expression and regulation DAT and VMAT2 associated with normal aging and (b) age-related alterations in the expression and regulation of DAT and VMAT2 under the conditions of environmental insults such as exposure to methamphetamine, and (c) the early adaptive changes in the expression and regulation of DAT and VMAT2 under growth factor deficiency (GDNF, and BDNF heterozygous transgenic animals) and the relationship to DA neuron vulnerability during aging processes. To accomplish this a number of dependent variables related to transporter function will be quantified, including 1) expression, transporter activity, sub-cellular distribution and 2) phosphorylation state of transporter, PP2Ac/alpha-synuclein -DAT association. These studies will aid in our understanding the compensatory changes occurring in DA neurons during normal aging process and could identify novel molecular targets for pharmacological intervention in age related neurodegenerative diseases.

衰老过程中运动和认知功能障碍的发展可能部分与中枢多巴胺（DA）神经传递的扰动有关。在分子水平上，DA信号传导受到多种大分子的动态调节，包括生物合成酶、降解酶、分泌蛋白、离子通道、突触前和突触后受体和转运蛋白。 DA 功能的各种异常被认为是各种类型的神经退行性疾病、精神病理学和药物成瘾的原因。多种神经元因子（例如神经营养因子）支持 DA 神经元的发育和神经可塑性。这些分子的表达和调节的改变或任何受损都可能导致 DA 神经元与年龄相关的脆弱性。质膜多巴胺转运蛋白 (DAT) 和囊泡单胺转运蛋白 (VMAT2) 对于正常 DA 至关重要 神经传递。 DAT 终止 DA 的作用并维持 DA 的细胞外水平，而 VMAT2 将细胞质 DA 加载到囊泡中，随后释放囊泡 DA 并维持细胞内细胞质 DA 水平。细胞内细胞质或升高的细胞外 DA 中高浓度的 DA 和/或 DA 代谢物被证明对纹状体突触前多巴胺能末梢具有毒性。因此，这两种转运蛋白功能的严格调节平衡的扰动可能会使神经元容易受到各种损伤的损害，例如生长因子缺乏或在不同寿命水平暴露于环境毒素。虽然 DAT mRNA 和结合位点的变化与衰老和帕金森病有关，但尚无研究调查与正常衰老相关的突触前 DA 末端转运蛋白功能、调节和亚细胞分布的相关变化。该项目的中心目标是了解衰老过程中 DAT 和 VMAT2 功能调节的神经适应性变化，并测试 DAT 和 VMAT2 的表达可以预测 DA 末端的选择性脆弱性的假设。该项目将最先进的生化和分子方法与动物核心中概述的动物模型相结合，系统地确定（a）与正常衰老相关的 DAT 和 VMAT2 表达和调节变化的进展，以及（b）与年龄相关的环境损害条件下 DAT 和 VMAT2 表达和调节的变化 例如暴露于甲基苯丙胺，以及（c）生长因子缺乏（GDNF 和 BDNF 杂合转基因动物）下 DAT 和 VMAT2 表达和调节的早期适应性变化以及衰老过程中与 DA 神经元脆弱性的关系。为了实现这一目标，将量化与转运蛋白功能相关的许多因变量，包括 1) 表达、转运蛋白活性、亚细胞分布和 2) 转运蛋白的磷酸化状态，PP2Ac/α-突触核蛋白-DAT 关联。这些研究将有助于我们了解正常衰老过程中 DA 神经元发生的代偿性变化，并可以确定针对年龄相关神经退行性疾病进行药物干预的新分子靶点。