Function of metal transporter ZIP14 as regulated by proinflammatory stimuli

说明(申请人提供)：锌是维持健康所必需的微量营养素。其潜在的机制尚不清楚，但有证据表明，锌在信号通路中具有控制作用，如蛋白激酶、蛋白磷酸酶和转录因子磷酸化。这种作用类似于细胞内离子浓度控制功能的钙。细胞使用来自两个基因家族的24种不同的锌转运蛋白将锌离子引导到细胞内位置。一些锌转运蛋白基因对膳食锌供应做出反应并参与体内平衡，而另一些基因则受细胞因子和激素的调节。我们已经鉴定了两个锌转运蛋白基因ZIP8和Zip14，它们对促炎细胞因子做出反应。ZIP8介导的锌离子从激活的T细胞溶酶体的转运使CREB保持在其磷酸化的论坛上，从而增强了IFNy的转录。我们已经证明，在IL6、IL12和一氧化氮刺激下，Zip14在肝细胞中被诱导。ZIP14可刺激锌离子的转运，并具有与金属反应转录因子MTF1相互作用等功能。这项建议的重点是利用Zip14基因敲除小鼠来探索ZIP14的生理作用。我们对这个项目的假设是，Zip14在促炎条件下上调，并运输锌在肝脏、胃肠道和肌肉中的功能。我们将通过三个相互关联的特定目标来验证我们的假设：1.表征Zip14-/-小鼠的表型，包括Zip14缺失对体内和原代细胞中金属运输的影响。2.探讨ZIP14在小鼠肝再生和炎症反应中的作用。3.炎症过程中肝脏、胃肠道和肌肉信号通路中Zip14基因缺失和表达的生理学后果。这些实验的基本原理是ZIP14(SLC39A14)转运蛋白对促炎刺激有反应，因此在许多病理生理条件下调节失调，产生改变的锌信号。这些人可能受益于补锌或旨在影响ZIP14活性的药物。

DESCRIPTION (provided by applicant): Zinc is an essential micronutrient that is required to maintain health. The underlying mechanisms are unknown, but evidence is emerging that zinc has roles in control of signaling pathways, e.g. protein kinases, protein phosphatases and transcription factor phosphorylation. The role is similar to that of calcium where the intracellular ion concentration controls functions. Cells use 24 different zinc transporter proteins derived from two gene families to direct zinc ions to intracellular sites. Some zinc transporter genes respond to the dietary zinc supply and participate in homeostasis, whereas a few others are regulated by cytokines and hormones. We have identified two zinc transporter genes Zip8 and Zip14, which respond to proinflammatory cytokines. ZIP8 mediated transport of Zn2+ from lysosomes of activated T cells maintains CREB in its phosphorylated forum enabling enhanced IFNy transcription. We have demonstrated that Zip14 is induced in hepatocytes upon stimulation by IL6, IL12 and nitric oxide. ZIP14 stimulates Zn2+ transport and has functional outcomes such as interaction with the metal responsive transcription factor, MTF1. The focus of this proposal is to explore the physiologic role of ZIP14 using Zip14 knockout mice. Our hypothesis for this project is that Zip14 is up-regulated by pro-inflammatory conditions and transports zinc for functions in liver, the gastrointestinal tract, and muscle. We will test our hypothesis through three interconnected specific aims: 1. Characterize the phenotype of the Zip14-/- mouse including the effects of Zip14 deletion on metal transport in vivo and in primary cells. 2. Evaluate the involvement of ZIP14 in murine liver regeneration and during inflammatory responses. 3. Physiologic consequences of Zip14 Deletion and Expression in signaling pathways in liver, gastrointestinal tract and muscle during inflammation. The rationale for these experiments is that the ZIP14 (SLC39A14) transporter is responsive to proinflammatory stimuli and hence is dysregulated in many pathophysiologic conditions producing altered zinc signaling. These may benefit from zinc supplementation or drugs designed to influence ZIP14 activity.