Selenium Alleviated Cadmium-induced Endoplasmic Reticulum Stress Via Regulation Of Calcium Homeostasis In LMH Cells

Cadmium is one of the most toxic pollutants in the natural environment and industrial environment. Because of a long half-life, Low rate of excretion and the high accumulation ability, it will continue to accumulate through the food chain and then enhance the harm to human and animals healths. The liver is one of the main target organs of cadmium accumulation and toxicity, Liver was the main target organ. The liver is also called “Selenium warehouse”. Dietary selenium can antagonize cadmium toxicity in liver, but the mechanism is still not clear.Calcium homeostasis is closely related to cell function and survival. In order to reveal the mechanism of selenium againsting cadmium induced liver cell toxicity. In this study, LMH cell as experimental object, exposure to Selenium and cadmium, and add 2-APB to inhibit calcium channels. MTT, MDC, q RT-PCR, flow cytometry and western blot were used to detect cell viability, endoplasmic reticulum stress, cell autophagy, calcium regulation and other related indexes. The study indicated that:(1) We successfully finished that the expression of the protein antigen polypeptide CNX and CRT, the preparation of CNX and CRT of rabbit polyclonal antibody against chicken, The Western blot method establishment to detective the protein level of CNX and CRT in both liver cells and tissues.(2) 24 h half inhibitory concentration of LMH cells which induced by cadmium and selenium were respectively 3.18 μM and 15.24 μM, suggesting that LMH cells are highly sensitive to cadmium. When cadmium and selenium in the ratio of 2:1 or 1:1, the selenium always could be able to antagonise the toxicity of liver cells induced by cadmium.(3) Cadmium could interfere with the mRNA expression of markers ATF4, ATF6, GRP78, GRP94, which signed endoplasmic reticulum stress, namely cadmium could induce LMH cells to endoplasmic reticulum stress, while cadmium could also increase the number of global autophagy in LMH cells and marker proteins Beclin1, P62, ATG3, ATG5 and ATG9 gene expression, besides, selenium could antagonise these changes effectively, these indicated that cadmium could induce autophagy and endoplasmic reticulum stress in LMH cell, which was one of the important mechanisms of the toxicity of cadmium, selenium could via inhibiting endoplasmic reticulum stress and autophagy exert antagonistic effect.(4) Cadmium could interfere with the content of free Ca2+ in LMH intracellular, and the expression of CaM and CaM-IV gene, increase the gene and protein expression level about CNX and CRT. Besides selenium could effectively antagonize the changes of these indexes, it showed that cadmium could induce regulation disorder of calcium homeostasis in LMH cells,which was important to the mechanism of Cd toxicity. selenium could antagonize Cd toxicity, through the effect of inhibit the disturbance of calcium homeostasis.(5) Application of 2-APB which inhibited storeoperated calcium channel established the cell model of calcium release blocked. Infected cadmium, the phenomenon of cytotoxicity, endoplasmic reticulum stress, autophagy was reduced, it showed that calcium homeostasis imbalance was the key mechanism of the toxicity of cadmium, at the same time the antagonistic effect of selenium was reduced, revealing the calcium homeostasis played a key role in the antagonistic effects of selenium on cadmium induced in LMH cell.