Hexavalent chromium-induced apoptosis in Hep3B cells is accompanied by calcium overload, mitochondrial damage, and AIF translocation
Hexavalent chromium-induced apoptosis in Hep3B cells is accompanied by calcium overload, mitochondrial damage, and AIF translocation
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六价铬诱导的 Hep3B 细胞凋亡伴有钙超载、线粒体损伤和 AIF 易位
DOI：
10.1016/j.ecoenv.2020.111391
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Ming Zeng
中科院分区：
文献类型：
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作者：
XiangFei Zhang;YuTing Wang;Ming Chen;Ming Zeng
六价铬[Cr(VI)]是一种普遍存在的环境污染物，可通过多种途径进入人体，引起器官毒性、遗传损伤和癌症。Cr（VI）诱导细胞凋亡是Cr（VI）的一种毒性机制。研究表明，Cr（VI）可诱导p53非依赖性细胞凋亡，但其机制尚不完全清楚。细胞内钙浓度影响细胞寿命。凋亡诱导因子（AIF）是一种不依赖于caspase的凋亡效应因子，可以诱导DNA降解。我们利用p53缺失的Hep3B细胞，研究了胞质钙稳态和AIF对Cr（VI）诱导的细胞凋亡的影响。我们发现，20µM的Cr（VI）诱导DNA损伤和线粒体通透性过渡孔（MPTP）打开，导致钙超载，并伴有Ca2+-Mg2+-ATP酶和Na+-K+-ATP活性降低，钙调素（CaM）和Ca2+/CaM依赖性蛋白激酶II (CAMKII) mRNA下调，p-CaMKII/ CAMKII蛋白表达增加。经钙螯合剂BAPTA-AM处理后，Cr(VI)-诱导的DNA损伤、钙超载和细胞凋亡减少。AIF从线粒体中释放并转移到细胞核中。随着Cr（VI）处理时间的延长，B细胞淋巴瘤2 （Bcl-2）和热休克蛋白70 （HSP70）的mRNA和蛋白表达量下降，Bcl-2相关的X （Bax）、亲环蛋白A （CypA）和内切酶G （EndoG）的mRNA和蛋白表达量上调。这些结果表明，Cr（VI）诱导的Hep3B细胞凋亡（p53-null）与钙超载密切相关，并伴有Ca2+/CaM/CaMKII信号通路的激活。此外，Cr （VI）在Hep3B细胞中引发AIF核易位，并伴有凋亡相关因子水平的变化。这些结果为Cr（VI）诱导p53非依赖性细胞凋亡的分子机制提供了额外的实验证据。
Hexavalent chromium [Cr(VI)] is a pervasive environmental pollutant that can enter the body through a variety of routes and cause organ toxicity, genetic damage, and cancer. Cr(VI)-induced apoptosis is a toxicant mechanism of Cr(VI). Studies have shown that Cr(VI) can induce p53-independent apoptosis, but the mechanisms are not fully understood. The intracellular calcium concentration affects cellular life. Apoptosis-inducing factor (AIF), a caspase-independent apoptotic effector, can induce DNA degradation. Using p53-null Hep3B cells, we investigated the effects of cytoplasmic calcium homeostasis and AIF on Cr(VI)-induced apoptosis. We found that 20 µM of Cr(VI) induced DNA damage and mitochondrial permeability transition pore (MPTP) openings, causing calcium overload that was accompanied by decreased Ca2+-Mg2+-ATPase and Na+-K+-ATP activities, downregulation of calmodulin (CaM) and Ca2+/CaM-dependent protein kinase II (CAMKII) mRNA, and increased expression of p-CaMKII/CaMKII protein. After treatment with calcium chelating agent BAPTA-AM, Cr(VI)- induced DNA damage, calcium overload, and apoptosis were reduced. AIF was released from the mitochondria and translocated into the nuclei. As the Cr(VI) treatment time progressed, the mRNA and protein expression of B cell lymphoma 2 (Bcl-2) and heat-shock protein 70 (HSP70) decreased, whereas the mRNA and protein expression of Bcl-2-associated X (Bax), cyclophilin A (CypA), and endonuclease G (EndoG) were upregulated. .These results indicated that Cr(VI)-induced apoptosis of Hep3B cells (p53-null) was closely associated with calcium overload, and was accompanied by the activation of Ca2+/CaM/CaMKII signaling pathway. Besides, Cr (VI) triggered AIF nuclear translocation in Hep3B cells, accompanied by the changes in the levels of apoptosisassociated factors. These results provide additional experimental evidence of the molecular mechanisms involved in Cr(VI)-induced p53-independent apoptosis.