ZnT9 function in the mitochondria

项目摘要。 锌是许多生物过程的关键，包括基因表达和酶活性，然而，它是 高浓度有毒。细胞暴露于高水平的锌导致酶活性的丧失， 活性氧（ROS）和细胞凋亡的激活。过量的锌对线粒体尤其有毒， 这是由于其能够抑制电子转移链的几种组分。在许多细胞器中锌浓度 由转座系统调节;然而，这种系统尚未显示用于线粒体。 使用生物信息学和细胞生物学测定的组合，我们已经将ZnT 9（SLC 30 A9）鉴定为一种新的蛋白质。 候选线粒体转运蛋白。该提案的首要目标是测试ZnT 9是一种生物活性的假设。 在控制和病理条件下线粒体锌的关键调节剂，其功能障碍可以 导致神经元损伤。我们认为，在正常情况下，线粒体质子梯度功率 锌从线粒体排出，限制锌毒性并提供神经保护功能。我们认为 在受损的线粒体中，ZnT 9被逆转，加速了损伤。这是锌的一个新功能， 转运蛋白和神经保护以及神经毒性的新机制。为了测试这个模型，我们将 追求两个具体目标。本项目的目标1集中于确定ZnT 9在以下方面的作用： 正常条件下和受损线粒体中的线粒体锌通量。目标2将回答是否 ZnT 9在锌超载和氧化应激条件下具有细胞保护作用， 加速神经细胞死亡。我们提出的研究可能会建立一个新的分子决定因素， 线粒体锌转运和以前未认识的锌神经毒性的组成部分。完成 本探索性/发展性研究计划中提出的研究，可能会为以下方面提供理论依据： 在体内小鼠模型中对ZnT 9功能和功能障碍的未来研究以及 这种转运蛋白可能与人类神经退行性疾病有关。

Project summary. Zinc is key to many of biological processes including gene expression and enzymatic activity, however, it is toxic at high levels. Exposure of cells to high levels of zinc leads to the loss of enzyme activity, generation of reactive oxygen species (ROS), and activation of apoptosis. Excess zinc is especially toxic to the mitochondria, due to its ability to inhibit several components of electron transfer chain. In many organelles zinc concentration is regulated by a system of transposers; however, such as system has not been shown for the mitochondria. Using a combination of bioinformatics and cell biological assays we have identified ZnT9 (SLC30A9) as a candidate mitochondrial transporter. The overarching goal of this proposal is to test the hypothesis that ZnT9 is a critical regulator of mitochondrial zinc under control and pathological conditions, and that its dysfunction can lead to neuronal injury. We propose that under normal conditions, the mitochondrial proton gradient powers zinc expulsion from the mitochondria, limiting zinc toxicity and providing a neuroprotection function. We think that in damages mitochondria ZnT9 is reversed, accelerating the damage. This is a novel function for a zinc transporter and a new mechanism of neuroprotection as well as neurotoxicity. To test this model, we will pursue two specific aims. Aim 1 of the present project is focused on identifying the role of ZnT9 in mitochondrial zinc fluxes under normal conditions and in damaged mitochondria. Aim 2 will answer whether ZnT9 is cytoprotective under zinc overload and oxidative stress conditions, and whether ZnT9 reversal accelerates neuronal cells death. Our proposed studies will likely establish a new molecular determinant of mitochondrial zinc transport and a previously unrecognized component of zinc neurotoxicity. The completion of the studies proposed in this Exploratory/Development Research Program will likely provide the rationale for future investigations of ZnT9 function and dysfunction in in vivo mouse models and an exploration of the possible link of this transporter to human neurodegenerative disorders.