The cytoprotective role of zinc transporters in human lung epithelia

描述(申请人提供)：上皮细胞凋亡是炎症性肺疾病急性肺损伤的一个标志，但对细胞死亡的原因知之甚少。为了研究这一点，我们将注意力集中在锌上，这是一种已知的哺乳动物细胞必不可少的细胞保护剂。我们实验室报告了炎性应激期间细胞内锌浓度调节后细胞存活率的显著差异。我们发现，在炎症应激过程中，锌启动了促进细胞存活和屏障功能的细胞内信号事件，而锌的枯竭则促进了细胞死亡和组织功能障碍。为了扩展这些研究，我们将注意力转向锌转运蛋白。锌的调节在后生动物中高度进化，由两个主要的锌转运蛋白家族组成。SLC39A家族作为锌进口者将膳食中的锌输送到细胞内，而SLC30A家族则通过将多余的锌输出到细胞外来起到平衡作用。这两个家族被认为对正常的细胞功能是不可或缺的，因为它们非常精确地维持细胞锌含量，但人们对它们在应激条件下的作用知之甚少。由于我们知道锌是炎症应激过程中肺上皮细胞不可或缺的组成部分，因此我们预测锌转运蛋白也有重要的作用。在前期研究中，我们发现只有锌进口子SLC39A8持续且高度上调，使其成为炎症应激时细胞内锌动员到肺上皮细胞的主要候选基因。在这项研究中，我们将检验这一中心假设，即炎症应激期间锌转运蛋白的表达和功能的调节是锌转运蛋白足够保护细胞免受死亡诱导刺激所必需的。为此，我们将解决四个具体目标：具体目标1：锌转运蛋白在人肺上皮细胞在急性炎症应激中的作用。具体目标2：SLC39A8将锌导入肺上皮细胞，以应对炎症反应，从而产生细胞保护作用。特异性目标3：锌对肺上皮细胞的生理影响，特异性目标4：锌转运蛋白作为肺上皮细胞功能障碍和疾病因子的个体间多态变异。这项建议的相关性在于，它将评估我们目前对锌代谢的理解中的一个重要差距，揭示对肺部疾病易感性的新见解，并可能产生预防急性肺损伤的创新策略。

DESCRIPTION (provided by applicant): Epithelial cell apoptosis is a hallmark of acute lung injury in inflammatory lung disease yet little is known about the cause of cell death. To study this we have focused our attention on zinc, a known cytoprotectant essential to mammalian cells. Our laboratory reported remarkable differences in cell viability following modulation of intracellular zinc concentration during inflammatory stress. We discovered that zinc initiates intracellular signaling events that promote cell survival and barrier function during inflammatory stress whereas zinc depletion promotes cell death and tissue dysfunction. To extend these studies we turned our attention to zinc transporter proteins. Zinc regulation is highly evolved in metazoa and is comprised of two major families of zinc transporter proteins. The SLC39A family functions as zinc importers to shuttle dietary zinc into the cell and the SLC30A family acts as a counterbalance by exporting excess zinc outside of the cell. Both families are believed to be indispensable for normal cell function as they maintain cellular zinc content with great precision yet little is known regarding their role during conditions of stress. Since we know that zinc is an indispensable component of the lung epithelium during inflammatory stress we predict that zinc transporters also have an essential role. In prelminary studies we made the striking observation that only the zinc importer SLC39A8 was consistently and highly up-regulated, establishing it as a lead candidate responsible for intracellular zinc mobilization into the lung epithelium during inflammatory stress. In this investigation we will test the central hypothesis that modulation of zinc transporter expression and function during inflammatory stress is required for zinc transport sufficient for cell protection against death-inducing stimuli. To do this we will address four specific aims: Specific Aim 1: The role of zinc transporters in human lung epithelium during acute inflammatory stress. Specific Aim 2: SLC39A8 directs zinc into the lung epithelium in response to inflammation leading to cytoprotection. Specific Aim 3: The physiologic consequences of zinc in lung epithelium, and Specific Aim 4: Inter-individual polymorphic variation of zinc transporters as a factor in lung epithelial cell dysfunction and disease. The relevance of this proposal is that it will evaluate an important gap in our current understanding of zinc metabolism, reveal new insight into lung disease susceptibility, and potentially generate innovative strategies to prevent acute lung injury.