CDF-1 REGULATION OF ZINC HOMEOSTASIS

描述（由申请人提供）：锌是一种深刻影响人类健康的必需营养素，因为锌缺乏和锌过量都会导致广泛的病理。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至关重要，锌调节信号转导途径。对锌代谢和体内平衡的详细了解对于开发新的方法来控制锌以促进人体健康至关重要。目前对动物锌代谢的认识还存在很大的空白，因为对锌的吸收、分布、感觉和排泄的基本机制还不清楚。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调节动物的锌代谢。这一目标将通过利用哺乳动物细胞和遗传易感模式生物秀丽隐杆线虫分析锌输入、锌输出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提供新的治疗方法。我们的初步结果已经建立了强大的秀丽隐杆线虫模型系统，通过发展培养条件，允许操纵膳食锌，创建测定锌代谢的方法，以及鉴定影响锌代谢的新基因突变，研究锌代谢。这些结果支持了三个创新的假设。(1) CDF-2通过将锌转运到溶酶体相关细胞器的腔内，在锌的储存和解毒中起关键作用。(2)溶酶体相关细胞器在高锌条件下呈双叶状，并提供锌的来源，在缺锌时被动员起来。(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。为了验证这些假设，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和铁转运蛋白在内的网络蛋白如何协调地调节锌的储存和动员。目的2：确定组氨酸解氨酶和组氨酸在哺乳动物细胞锌代谢中的作用。在秀丽隐杆线虫和哺乳动物中鉴定和表征介导锌代谢的新基因。这些实验建立在我们在之前的资助期所取得的成就之上，即建立了秀丽隐杆线虫锌代谢研究的模型系统。这一建议将这些发现扩展到脊椎动物系统，并利用秀丽隐杆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的锌储存和动员。一些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，这些研究结果可能为解决锌毒性疾病提供新的治疗策略。

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.