CDF-1 REGULATION OF ZINC HOMEOSTASIS

描述(申请人提供)：锌是一种重要的营养物质，对人类健康有深远的影响，因为锌缺乏和锌过量都会导致广泛的病理变化。锌在生物系统中扮演着许多角色，因为锌对许多蛋白质的功能是必不可少的，并且锌调节信号转导途径。对锌代谢和动态平衡的详细了解对于开发新的锌操作方法以促进人类健康至关重要。目前对动物体内锌代谢的了解存在很大差距，因为对锌的吸收、分布、感觉和排泄的基本机制还不是很清楚。我们的长期目标是了解锌转运蛋白和结合蛋白网络如何以协调的方式发挥作用，调节动物体内的锌代谢。这一目标将通过利用哺乳动物细胞和遗传易驯化的模式生物秀丽线虫分析锌进口商、锌出口商和参与锌代谢的新基因来实现。了解蛋白质网络如何控制动物体内的锌代谢是医学研究的一个重要目标，因为这些信息可能会为锌代谢异常引起的疾病带来新的治疗方法。我们的初步结果已经建立了用于研究锌代谢的强大的线虫模型系统，通过发展允许操纵饮食锌的培养条件，建立了测量锌代谢的分析方法，并鉴定了影响锌代谢的新基因的突变。这些结果支持三个创新假说。(1)CDF-2通过将锌转运到溶酶体相关细胞器的管腔中，在锌的储存和解毒中发挥重要作用。(2)溶酶体相关细胞器在高锌条件下呈双叶形态，并提供锌的来源，在缺锌时被动员。(3)组氨酸解氨酶在锌代谢中起重要作用，高水平的组氨酸促进锌的解毒作用。为了检验这些假设，我们提出了两个具体目标。目的1：明确CDF-2和溶酶体相关细胞器在锌储存中的作用。阐明包括CDF、ZIP和铁蛋白在内的一个网络蛋白如何以一种协调的方式调节锌的储存和动员。目的：研究组氨酸解氨酶和组氨酸在哺乳动物细胞锌代谢中的作用。识别和表征在线虫和哺乳动物中调节锌代谢的新基因。这些实验建立在我们在前一个资助期取得的成就的基础上，该资助期为研究锌代谢建立了线虫模型系统。这项提议将把这些发现扩展到脊椎动物系统，并利用线虫强大的实验优势来阐明基因网络如何调节多细胞动物中锌的储存和动员。几种常见的人类疾病，如阿尔茨海默病、中风和癌症，都与锌代谢异常有关，这些研究结果可能会为解决锌中毒的障碍提供新的治疗策略。

DESCRIPTION (provided by applicant): Zinc is an essential nutrient that profoundly affects human health, as zinc deficiency and zinc excess both result in a broad spectrum of pathologies. Zinc plays many roles in biological systems, since zinc is essential for the function of many proteins and zinc modulates signal transduction pathways. A detailed understanding of zinc metabolism and homeostasis is critical for the development of new approaches for manipulating zinc to promote human health. There are major gaps in the current understanding of zinc metabolism in animals, since fundamental mechanisms used to take up, distribute, sense and excrete zinc are not well understood. Our long-term goal is to understand how a network of zinc transporters and binding proteins act in a coordinated fashion to regulate zinc metabolism in animals. This goal will be addressed by analyzing zinc importers, zinc exporters and new genes involved in zinc metabolism using mammalian cells and the genetically tractable model organism C. elegans. Understanding how a network of proteins controls zinc metabolism in an animal is an important objective of medical research, since the information may lead to new therapeutic approaches for diseases caused by abnormal zinc metabolism. Our preliminary results have established the powerful C. elegans model system for studies of zinc metabolism by the development of culture conditions that permit manipulation of dietary zinc, the creation of assays that measure zinc metabolism, and the identification of mutations in new genes that affect zinc metabolism. These results support three innovative hypotheses. (1) CDF-2 plays a critical role in zinc storage and detoxification by transporting zinc into the lumen of lysosome-related organelles. (2) Lysosome-related organelles adopt a bilobed morphology in response to high zinc conditions and provide a source of zinc that is mobilized during deficiency. (3) Histidine ammonia lyase plays an important role in zinc metabolism, and high levels of histidine promote zinc detoxification. To test these hypotheses, we propose two specific aims. Aim 1: Define the role of CDF-2 and lysosome-related organelles in zinc storage. Elucidate how a network proteins including CDF, ZIP and ferroportin function in a coordinated manner to regulate zinc storage and mobilization. Aim 2: Determine the function of histidine ammonia lyase and histidine in zinc metabolism in mammalian cells. Identify and characterize new genes that mediate zinc metabolism in C. elegans and mammals. These experiments build on our accomplishments in the previous grant period that established the C. elegans model system for studies of zinc metabolism. This proposal will extend these discoveries to vertebrate systems and exploit the powerful experimental advantages of C. elegans to elucidate how a network of genes regulates zinc storage and mobilization in a multicellular animal. Several prevalent human diseases such as Alzheimer's disease, stroke and cancer have been associated with abnormalities of zinc metabolism, and the results of these studies may suggest new therapeutic strategies for addressing disorders of zinc toxicity.