Plum Laura Marie, Brieger Anne, Engelhardt Gabriela, Hebel Silke, Nessel Andreas, Arlt Marcus, Kaltenberg Jennifer, Schwaneberg Ulrich, Huber Michael, Rink Lothar, Haase Hajo
Institute of Immunology, Medical Faculty, RWTH Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany.
Metallomics. 2014 Jul;6(7):1277-87. doi: 10.1039/c3mt00197k.
Free zinc ions (Zn(2+)) participate in several signaling pathways. The aim of the present study was to investigate a potential involvement of Zn(2+) in the PI3K/Akt pathway of interleukin (IL)-2 signaling in T-cells. The IL-2 receptor triggers three major pathways, ERK1/2, JAK/STAT5, and PI3K/Akt. We have previously shown that an IL-2-mediated release of lysosomal Zn(2+) into the cytoplasm activates ERK1/2, but not STAT5. In the present study, Akt phosphorylation in response to IL-2 was abrogated by the Zn(2+) chelator N,N,N',N'-tetrakis-2(pyridyl-methyl)ethylenediamine, and was induced by treatment with Zn(2+) and the ionophore pyrithione. The latter were ineffective in cells that were treated with siRNA against the phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a phosphatase that degrades the lipid second messenger PI(3,4,5)P3, which is produced by PI3K and leads to activation of Akt. Inhibition of recombinant PTEN by Zn(2+)in vitro yielded an IC50 of 0.59 nM. Considering a resting free cytoplasmic Zn(2+) level of 0.2 nM in the T-cell line CTLL-2, this seems ideally suited for dynamic regulation by cellular Zn(2+). Oxidation with H2O2 and supplementation with Zn(2+) led to similar changes in the CD spectrum of PTEN. Moreover, Zn(2+) partially prevented the oxidation of cysteines 71 and 124. Hence, we hypothesize that zinc signals affect the IL-2-dependent PI3K/Akt pathway by inhibiting the negative regulator PTEN through binding with a sub-nanomolar affinity to cysteine residues that are essential for its catalytic activity.
游离锌离子（Zn(2+)）参与多种信号通路。本研究的目的是探讨Zn(2+)在T细胞白细胞介素（IL）-2信号转导的PI3K/Akt通路中的潜在作用。IL-2受体触发三条主要通路，即ERK1/2、JAK/STAT5和PI3K/Akt。我们之前已经表明，IL-2介导的溶酶体Zn(2+)释放到细胞质中可激活ERK1/2，但不能激活STAT5。在本研究中，Zn(2+)螯合剂N,N,N',N'-四（2-吡啶甲基）乙二胺可消除IL-2诱导的Akt磷酸化，而Zn(2+)和离子载体吡啶硫酮处理可诱导Akt磷酸化。在使用针对10号染色体缺失的磷酸酶和张力蛋白同源物（PTEN）的小干扰RNA（siRNA）处理的细胞中，后者无效，PTEN是一种可降解脂质第二信使PI(3,4,5)P3的磷酸酶，PI(3,4,5)P3由PI3K产生并导致Akt激活。Zn(2+)在体外对重组PTEN的抑制作用产生的半数抑制浓度（IC50）为0.59 nM。考虑到T细胞系CTLL-2中静息游离细胞质Zn(2+)水平为0.2 nM，这似乎非常适合细胞内Zn(2+)进行动态调节。用H2O2氧化并补充Zn(2+)导致PTEN的圆二色光谱发生类似变化。此外，Zn(2+)部分阻止了半胱氨酸71和124的氧化。因此，我们推测锌信号通过以亚纳摩尔亲和力与对其催化活性至关重要的半胱氨酸残基结合来抑制负调节因子PTEN，从而影响IL-2依赖性PI3K/Akt通路。
