Molecular functions of human zinc transporter-8 in pancreatic beta cells

摘要 锌是一种普遍存在的生物金属，存在于约10%的真核生物蛋白质组中。时空锌 动态提供了关键的细胞信号机会，但也挑战了细胞内锌稳态， 广泛的疾病影响。锌转运蛋白在调节细胞锌平衡和亚细胞锌代谢中起着重要作用。 锌分布目前锌转运蛋白的生物化学主要基于试管中纯化的蛋白质。 然而，哺乳动物细胞中锌转运蛋白的分子功能是细胞环境依赖性的，随着细胞内环境的变化而变化。 亚细胞位置和调节的病理生理刺激。目前，我们对in-cell 内源性锌转运蛋白在分子水平上的功能。为了填补这一知识真空，我们将使用 胰岛特异性锌转运蛋白ZnT 8及其宿主细胞--哺乳动物胰岛β细胞 模型系统，以解决两个最重要的问题，锌生物学：（i）如何ZnT 8介导的锌 运输在正确的亚细胞位置被区室化以执行预期的任务，（ii） ZnT 8的生物合成负荷由蛋白质质量控制网络管理，该网络确保ZnT 8的清除。 在细胞应激下末端受损的ZnT 8。第二个问题与锌的运输没有直接关系， 对β细胞生物学的深刻影响，并暗示2型糖尿病的发病机制。我们之前的研究 揭示了ZnT 8和胰岛素在两个关键细胞过程中的功能偶联，葡萄糖刺激的胰岛素 分泌和炎症诱导的内质网中未折叠蛋白反应。拟议 研究将表征内源性ZnT 8的亚细胞位置和蛋白水平，以响应代谢 和炎症应激（Aim-1），鉴定ZnT 8亚细胞功能的调节剂，并阐明其机制 行动（目标-2）。这项研究将揭示ZnT 8亚细胞的前所未有的分子细节。 在分子和细胞过程中的功能，影响宿主细胞的细胞生物学，导致一种新的范式， 哺乳动物细胞中锌转运蛋白的细胞内分子功能。

Abstract Zinc is a ubiquitous biological metal found in about 10% of the eukaryotic proteome. The spatiotemporal zinc dynamics provides crucial cellular signaling opportunities, but also challenges intracellular zinc homeostasis with broad disease implications. Zinc transporters play a central role in regulating cellular zinc balance and subcellular zinc distributions. Current biochemistry of zinc transporters is largely based on purified proteins in test-tubes. However, the molecular functions of zinc transporters in mammalian cells are cell context dependent, vary with subcellular locations and regulated by pathophysiologic stimuli. At present, we have no knowledge of in-cell functions of endogenous zinc transporters at the molecular level. To fill in this knowledge vacuum, we will use an islet-specific zinc transporter ZnT8 and its host cells, the insulin-producing pancreatic β-cells as a mammalian model system to address two questions of the greatest importance to zinc biology: (i) how ZnT8-mediated zinc transport is compartmentalized at the correct subcellular locations to perform intended tasks, (ii) how the biosynthetic burden of ZnT8 is managed by the protein quality control network that ensures clearance of terminally damaged ZnT8 under cell stress. The second question is not directly related to zinc transport, but has a profound impact on β-cell biology with implications in pathogenesis of type-2 diabetes. Our prior studies have uncovered functional coupling of ZnT8 and insulin in two critical cellular processes, glucose-stimulated insulin secretion and inflammation-induced unfolded protein response in the endoplasmic reticulum. The proposed research will characterize subcellular locations and protein levels of endogenous ZnT8 in response to metabolic and inflammatory stress (Aim-1), identify regulators of ZnT8 subcellular functions, and elucidate their mechanism of actions (Aim-2). The proposed research will reveal unprecedented molecular details of ZnT8 subcellular functions in molecular and cellular processes that impact cell biology of host cells, leading to a new paradigm of in-cell molecular functions of zinc transporters in mammalian cells.