Effects of salubrinal on cadmium-induced apoptosis in HK-2 human renal proximal tubular cells
Effects of salubrinal on cadmium-induced apoptosis in HK-2 human renal proximal tubular cells
复制标题
DOI：
10.1007/s00204-011-0742-x
复制
发表时间：
2012-01-01
影响因子：
6.1
通讯作者：
Matsuoka, Masato
中科院分区：
文献类型：
--
作者：
Komoike, Yuta;Inamura, Hisako;Matsuoka, Masato
众所周知，镉暴露会导致内质网(ER)应激。在我们目前的研究中，我们研究了真核细胞翻译起始因子2亚单位α(eIF2α)去磷酸化的选择性抑制剂salubrine对氯化镉(Cd Cl2)诱导的HK-2人肾小管上皮细胞凋亡和内质网应激信号事件的影响。利用相差显微镜和细胞存活率测定，我们观察到三氯甲烷抑制了氯化镉诱导的细胞损伤和细胞死亡。Salubrine处理减少了TUNEL阳性细胞的数量以及caspase-3和聚(ADP-核糖)聚合酶的裂解，但没有减少轻链3B的裂解，这表明对氯化镉诱导的细胞凋亡有保护作用，但对自噬没有保护作用。经氯化镉处理的HK-2细胞经氯化镉处理后，eIF2α仍保持磷酸化，但激活转录因子4(ATF4)和78 kDa葡萄糖调节蛋白(GRP78)的表达并未增加。另一方面，生理盐水处理可降低氯化镉诱导的C/EBP同源蛋白(CHOP)的表达。GRP78和CHOP的上游调节因子ATF4的表达似乎是Salubrine完全保护细胞免受镉细胞毒性的先决条件，因为在ATF4缺乏的细胞中，CdCl2诱导的细胞损伤并未完全被抑制。氯化镉暴露后，丝裂原活化蛋白激酶(MAPKs)的磷酸化形式，包括c-jun氨基末端激酶(JNK)、p38和细胞外信号调节蛋白激酶(ERK)增加，而Salubrine抑制JNK和p38的磷酸化，但不抑制ERK。这些结果表明，三氯甲烷通过抑制细胞死亡信号转导通路，保护镉暴露的HK-2细胞免于凋亡。
Cadmium exposure is known to cause endoplasmic reticulum (ER) stress. In our current study, we examined the effects of salubrinal, a selective inhibitor of eukaryotic translation initiation factor 2 subunit alpha (eIF2 alpha) dephosphorylation, on apoptotic cell death and ER stress-signaling events in HK-2 human renal proximal tubular cells exposed to cadmium chloride (CdCl2). Using phase-contrast microscopy and a cell viability assay, we observed that salubrinal suppressed CdCl2-induced cellular damage and cell death. Treatment with salubrinal reduced the number of TUNEL-positive cells and the cleavages of caspase-3 and poly(ADP-ribose) polymerase, but not the cleavage of light chain 3B, indicating protection from CdCl2-induced apoptosis but not autophagy. Although eIF2 alpha remained phosphorylated after CdCl2 exposure to salubrinal-treated HK-2 cells, the expression of activating transcription factor 4 (ATF4) and the 78 kDa glucose-regulated protein (GRP78) was not increased. On the other hand, CdCl2-induced expression of C/EBP homologous protein (CHOP) was reduced by salubrinal treatment. Expression of ATF4, an upstream regulator of GRP78 and CHOP, appeared to be a prerequisite for full protection by salubrinal against cadmium cytotoxicity, because CdCl2-induced cellular damage was not fully suppressed in ATF4-deficient cells. Phosphorylated forms of mitogen-activated protein kinases (MAPKs), including c-Jun NH2-terminal kinase (JNK), p38, and extracellular signal-regulated protein kinase (ERK), increased after CdCl2 exposure, whereas salubrinal suppressed the phosphorylation of JNK and p38 but not ERK. These results suggest that salubrinal protects CdCl2-exposed HK-2 cells from apoptosis by suppressing cell death signal transduction pathways.