Intracellular Pathways of Manganese Trafficking

描述（由申请人提供）：锰是一种必需的微量营养素，也具有潜在毒性。在哺乳动物中，锰是一种有效的神经毒素，并与帕金森病样综合征有关。然而，令人惊讶的是，关于这种金属的细胞生物学及其毒性机制知之甚少。我们一直在利用面包酵母。酿酒酵母作为模型系统，以表征真核细胞因子，控制锰稳态。在过去的资助期间，我们已经确定了一些这样的因素，包括：Smf 2 p，NRAMP金属转运蛋白，定位于细胞内囊泡，并在锰运输中发挥核心作用; Mtm 1 p，线粒体的推定锰转运蛋白;和磷酸盐代谢因子，是锰毒性的关键决定因素。通过四个具体的目标，我们将继续我们的调查，这些和其他锰稳态因素。我们的目标是：（1）确定Smf 2 p锰转运囊泡的性质，并阐明内吞作用在锰的摄取和胞内运输中的作用;（2）阐明酵母和人Mtm 1 p在锰转运到线粒体基质中的作用;（3）确定磷酸盐代谢途径如何调节细胞对锰毒性的抵抗力;和（4）利用酵母遗传学鉴定新的锰稳态因子，包括推定的锰金属伴侣。总的来说，这些研究将联合收割机酵母分子遗传学，生物化学和细胞生物学的不同学科，提供新的见解，必要的，但潜在的毒性锰离子的稳态。

DESCRIPTION (provided by applicant): Manganese is an essential trace nutrient that is also potentially toxic. In mammals, manganese is a potent neurotoxin and has been implicated in Parkinson's disease-like syndromes. Yet surprisingly little is known regarding the cell biology of this metal and its mechanisms of toxicity. We have been exploiting the bakers' yeast S. cerevisiae as a model system to characterize eukaryotic factors that control manganese homeostasis. Over the past funding period, we have identified a number of such factors including: Smf2p, a NRAMP metal transporter that localizes to intracellular vesicles and plays a central role in manganese trafficking; Mtm1p, a putative manganese transporter for the mitochondria; and phosphate metabolism factors that are critical determinants of manganese toxicity. Through four specific aims, we will continue our investigations of these and other manganese homeostasis factors. Our goals are to (1) Define the nature of the Smf2p manganese transport vesicles and to address the role of endocytosis in the uptake and intracellular trafficking of manganese; (2) Elucidate the role of yeast and human Mtm1p in the transport of manganese into the mitochondrial matrix; (3) Determine how phosphate metabolism pathways modulate cellular resistance to manganese toxicity; and (4) Employ yeast genetics to identify new manganese homeostasis factors, including putative manganese metallochaperones. Overall, these studies will combine diverse disciplines of yeast molecular genetics, biochemistry and cell biology to provide new insight into the homeostasis of essential, but potentially toxic manganese ions.