Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Republic of Korea.
Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Republic of Korea.
Toxicol Lett. 2014 Oct 1;230(1):69-79. doi: 10.1016/j.toxlet.2014.07.027. Epub 2014 Aug 8.
In this study, we identified the toxic effects of sheet-type titania (TNS), which are being developed as a material for UV-blocking glass, comparing with P25, a benchmark control for titania, in MH-S cells, a mouse alveolar macrophage cell line. After 24 h exposure, the TNS-exposed cells formed large vacuoles while the P25-exposed ones did not. The decreased levels of cell viability were similar between the P25 and TNS groups, but ATP production was clearly lower in cells exposed to the TNS. P25 decreased the expression of calnexin protein, an endoplasmic reticulum (ER) membrane marker, and increased the number of cells generating ROS in a dose dependent manner. Meanwhile, TNS dilated the ER and mitochondria and increased the secretion of NO and pro-inflammatory cytokines, but not of ROS. Subsequently, we studied the molecular response following TNS-induced vacuolization. TNS started to form vacuoles in the cytosol since 20 min after exposure, and the expression of the mitochondria function-related genes were down-regulated the most in the cells exposed for 1 h. After 24 h exposure, the number of apoptotic cells and the relative levels of BAX to Bcl-2 increased. The expression of SOD1 protein, but not of SOD2, also dose-dependently increased with an increase in caspase-8 activity. Additionally, the MAPK pathway was significantly activated, even though the expression of p-EGFR did not change significantly. Furthermore, the number of apoptotic cells increased rapidly with time and with the inhibition of vacuole formation. Taken together, we suggest that P25 and TNS may target different organelles. In addition, TNS, but not P25, induced paraptosis accompanied by apoptosis in MH-S cells, and the formation of the cytoplasmic vacuoles allowed delay apoptosis following TNS exposure.
在这项研究中，我们比较了片层状二氧化钛（TNS）和 P25（二氧化钛的基准对照物）对 MH-S 细胞（一种鼠肺泡巨噬细胞系）的毒性作用，TNS 正在被开发为一种用于防紫外线玻璃的材料。在 24 小时暴露后，TNS 暴露的细胞形成了大的空泡，而 P25 暴露的细胞则没有。P25 和 TNS 组的细胞活力下降水平相似，但 TNS 暴露组的 ATP 产生明显降低。P25 以剂量依赖的方式降低内质网（ER）膜标志物 calnexin 蛋白的表达，并增加产生 ROS 的细胞数量。同时，TNS 扩张 ER 和线粒体，并增加 NO 和促炎细胞因子的分泌，但不增加 ROS 的分泌。随后，我们研究了 TNS 诱导的空泡化后的分子反应。TNS 在暴露后 20 分钟开始在细胞质中形成空泡，并且在暴露 1 小时的细胞中，与线粒体功能相关的基因表达下调最多。暴露 24 小时后，凋亡细胞的数量和 BAX 与 Bcl-2 的相对水平增加。SOD1 蛋白的表达，但不是 SOD2，也随着 caspase-8 活性的增加而呈剂量依赖性增加。此外，MAPK 途径被显著激活，尽管 p-EGFR 的表达没有明显变化。此外，随着时间的推移和空泡形成的抑制，凋亡细胞的数量迅速增加。综上所述，我们认为 P25 和 TNS 可能靶向不同的细胞器。此外，TNS 而非 P25 诱导 MH-S 细胞发生伴凋亡的 Paraptosis，细胞质空泡的形成允许 TNS 暴露后延迟凋亡。
