Department of Endocrinology, Diabetology and Clinical Nutrition, University Hospital Zurich (USZ) and University of Zurich (UZH), Zurich, Switzerland.
Institute of Metabolism and Systems Research (IMSR) and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK.
J Endocrinol. 2022 Feb 11;253(1):1-11. doi: 10.1530/JOE-21-0271.
Pancreatic β-cells depend on the well-balanced regulation of cytosolic zinc concentrations, providing sufficient zinc ions for the processing and storage of insulin, but avoiding toxic effects. The zinc transporter ZnT8, encoded by SLC30A8,is a key player regarding islet cell zinc homeostasis, and polymorphisms in this gene are associated with altered type 2 diabetes susceptibility in man. The objective of this study was to investigate the role of ZnT8 and zinc in situations of cellular stress as hypoxia or inflammation. Isolated islets of WT and global ZnT8-/- mice were exposed to hypoxia or cytokines and cell death was measured. To explore the role of changing intracellular Zn2+ concentrations, WT islets were exposed to different zinc concentrations using zinc chloride or the zinc chelator N,N,N',N'-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN). Hypoxia or cytokine (TNF-α, IFN-γ, IL1-β) treatment induced islet cell death, but to a lesser extent in islets from ZnT8-/- mice, which were shown to have a reduced zinc content. Similarly, chelation of zinc with TPEN reduced cell death in WT islets treated with hypoxia or cytokines, whereas increased zinc concentrations aggravated the effects of these stressors. This study demonstrates a reduced rate of cell death in islets from ZnT8-/- mice as compared to WT islets when exposed to two distinct cellular stressors, hypoxia or cytotoxic cytokines. This protection from cell death is, in part, mediated by a reduced zinc content in islet cells of ZnT8-/- mice. These findings may be relevant for altered diabetes burden in carriers of risk SLC30A8 alleles in man.
胰岛β细胞依赖于细胞溶质锌浓度的平衡调节,为胰岛素的加工和储存提供足够的锌离子,但又要避免毒性作用。锌转运蛋白 ZnT8 由 SLC30A8 编码,是胰岛细胞锌稳态的关键因素,该基因的多态性与人类 2 型糖尿病易感性的改变有关。本研究旨在探讨 ZnT8 和锌在细胞应激(如缺氧或炎症)情况下的作用。用氯化锌或锌螯合剂 N,N,N',N'-四(2-吡啶基甲基)-1,2-乙二胺(TPEN)将 WT 和全球 ZnT8-/- 小鼠的胰岛暴露于缺氧或细胞因子中,并测量细胞死亡。为了研究改变细胞内 Zn2+浓度的作用,用不同浓度的氯化锌或锌螯合剂 N,N,N',N'-四(2-吡啶基甲基)-1,2-乙二胺(TPEN)处理 WT 胰岛,以观察细胞内 Zn2+浓度的变化。缺氧或细胞因子(TNF-α、IFN-γ、IL1-β)处理诱导胰岛细胞死亡,但在 ZnT8-/- 小鼠的胰岛中程度较轻,ZnT8-/- 小鼠的胰岛锌含量降低。同样,用 TPEN 螯合锌可减少缺氧或细胞因子处理的 WT 胰岛中的细胞死亡,而增加锌浓度则加重了这些应激因素的作用。本研究表明,与 WT 胰岛相比,暴露于两种不同细胞应激源(缺氧或细胞毒性细胞因子)时,ZnT8-/- 小鼠的胰岛细胞死亡速度较慢。这种对细胞死亡的保护作用部分是由 ZnT8-/- 小鼠胰岛细胞中的锌含量降低介导的。这些发现可能与携带人类 SLC30A8 等位基因的个体糖尿病负担改变有关。