TRANSCRIPTIONAL REGULATION OF ZINC HOMEOSTASIS

 描述（由申请人提供）：锌是一种重要的营养素，深刻影响人类健康，因为锌缺乏和过量都会导致广泛的病理学。锌在生物系统中起着许多作用，因为锌对许多蛋白质的功能是必需的，并且锌调节信号转导途径。详细了解锌的运输和体内平衡对于开发新的方法来操纵锌以促进人类健康至关重要。目前对动物体内锌稳态的理解存在重大差距，因为用于摄取、感知和排泄锌的基本机制还不清楚。我们的长期目标是阐明动物如何感知锌水平并协调促进锌稳态的反应。这一目标将通过使用哺乳动物细胞和遗传上易处理的模式生物C分析锌调节的转录因子和靶基因来解决。优雅了解蛋白质网络如何控制动物体内的锌稳态是医学研究的一个重要目标，因为这些信息可能会导致由异常锌生物学引起的疾病的新治疗方法。我们的初步结果建立了强大的C。elegans模型系统，用于锌生物学研究，通过开发允许操纵膳食锌的培养条件，建立测量锌含量和分布的测定法，以及鉴定控制锌生物学的基因突变。这些结果支持了三个创新假设。(1)HZA增强子介导响应于过量锌的多个基因的转录激活。核受体NHR-33受高膳食锌的调节，并结合HZA增强子以控制介导稳态的靶基因。(2)ZIP转运蛋白Y54G9A.4促进锌的吸收，并受低膳食锌的调节。(3)LZA增强子介导响应锌缺乏的多个基因的转录激活。为了验证这些假设，我们提出了三个具体目标。目的1：研究锌稳态中核受体的调控和进化保守性。目的2：筛选高锌饮食调控的靶基因并进行功能分析。目的3：分析ZIP基因Y54G9A.4的功能和调控。表征LZA增强子介导的转录调节，以响应锌缺乏，并确定蛋白质因子，调节这个元素。这些实验建立在我们在前一个资助期内所取得的成就的基础上。elegans模型系统的锌生物学研究，并产生了创新的新假说。这项提议将把这些发现扩展到哺乳动物系统，并利用C。elegans来阐明基因网络如何调节多细胞动物中的锌稳态。几种流行的人类疾病，如阿尔茨海默病，中风和癌症已与锌稳态异常，这些研究的结果可能会提出新的治疗策略，以解决锌毒性疾病。

 DESCRIPTION (provided by applicant): Zinc is an essential nutrient that profoundly affects human health, as zinc deficiency and 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 trafficking 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 homeostasis in animals, since fundamental mechanisms used to take up, sense, and excrete zinc are not well understood. Our long- term goal is to elucidate how animals sense zinc levels and coordinate a response that promotes zinc homeostasis. This goal will be addressed by analyzing zinc-regulated transcription factors and target genes using mammalian cells and the genetically tractable model organism C. elegans. Understanding how a network of proteins controls zinc homeostasis 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 biology. Our preliminary results have established the powerful C. elegans model system for studies of zinc biology by the development of culture conditions that permit manipulation of dietary zinc, the establishment of assays that measure zinc content and distribution, and the identification of mutations in genes that control zinc biology. These results support three innovative hypotheses. (1) The HZA enhancer mediates transcriptional activation of multiple genes in response to excess zinc. The nuclear receptor NHR-33 is regulated by high dietary zinc and binds the HZA enhancer to control target genes that mediate homeostasis. (2) The ZIP transporter Y54G9A.4 promotes zinc uptake and is regulated by low dietary zinc. (3) The LZA enhancer mediates transcriptional activation of multiple genes in response to zinc deficiency. To test these hypotheses, we propose three specific aims. Aim 1: Characterize the regulation and evolutionary conservation of nuclear receptors in mediating zinc homeostasis. Aim 2: Identify and functionally analyze target genes regulated by high dietary zinc. Aim 3: Analyze the function and regulation of the ZIP gene Y54G9A.4. Characterize the LZA enhancer that mediates transcriptional regulation in response to zinc deficiency, and identify protein factors that regulae this element. These experiments build on our accomplishments in the previous grant period that established the C. elegans model system for studies of zinc biology and generated innovative new hypotheses. This proposal will extend these discoveries to mammalian systems and exploit the powerful experimental advantages of C. elegans to elucidate how a network of genes regulates zinc homeostasis in a multicellular animal. Several prevalent human diseases such as Alzheimer's disease, stroke and cancer have been associated with abnormalities of zinc homeostasis, and the results of these studies may suggest new therapeutic strategies for addressing disorders of zinc toxicity.