Biochemistry Laboratory, Central Leather Research Institute, Adyar, Chennai-600020, India.
Toxicol Appl Pharmacol. 2010 Mar 15;243(3):405-19. doi: 10.1016/j.taap.2009.12.018. Epub 2010 Jan 4.
We have studied the effect of Cr(III)(phen)3 [(tris(1,10-phenanthroline) chromium(III) chloride)] on lymphocytes in order to find out if metallothioneins (MTs) are produced in the process. We also investigated whether zinc pretreatment is able to protect cells from apoptosis reported to occur for this compound. Our results indicate that MT synthesis is induced by Cr(III)(phen)3, and it has been identified as the MT-3 isoform through RT-PCR which has not been reported earlier. By zinc pretreatment, this apoptosis is reversed as inferred from cytotoxicity studies, Annexin-V/PI staining, ethidium bromide/acridine orange staining and DNA fragmentation pattern and ultrastructural investigations using TEM and SEM. The zinc pretreatment reduces the amount of ROS produced by Cr(III)(phen)3. The MT-1a and 1b synthesized by zinc (also evidenced through RT-PCR experiments) is possibly able to scavenge ROS which is one of the early signaling molecules that lead to apoptosis. Zinc pretreatment also reverses the changes in downstream signaling events such as mitochondrial membrane potential, ATP levels and the activation of caspase-3. This is the first report on the induction of MT-3 in lymphocytes due to a metal stress or any other stimuli. Even though MT-3 is synthesized here, apoptosis still occurs due to ROS production on Cr(III)(phen)3 exposure when the cells have not been primed with zinc.
我们研究了 Cr(III)(phen)3[(三（1,10-菲啰啉）氯化铬（III）]对淋巴细胞的影响，以了解在此过程中是否产生金属硫蛋白 (MTs)。我们还研究了锌预处理是否能够保护细胞免受该化合物报道的细胞凋亡。我们的结果表明，MT 的合成被 Cr(III)(phen)3 诱导，并且通过 RT-PCR 鉴定为 MT-3 同工型，这在以前的研究中尚未报道。通过锌预处理，从细胞毒性研究、Annexin-V/PI 染色、溴化乙锭/吖啶橙染色和 DNA 片段化模式以及使用 TEM 和 SEM 的超微结构研究推断出这种细胞凋亡得到逆转。锌预处理减少了 Cr(III)(phen)3 产生的 ROS 量。锌合成的 MT-1a 和 1b（也通过 RT-PCR 实验证实）可能能够清除 ROS，ROS 是导致细胞凋亡的早期信号分子之一。锌预处理还逆转了下游信号事件的变化，如线粒体膜电位、ATP 水平和 caspase-3 的激活。这是第一个关于金属应激或任何其他刺激物导致淋巴细胞中 MT-3 诱导的报告。即使在此处合成了 MT-3，但由于细胞未用锌预先处理而导致 Cr(III)(phen)3 暴露时产生 ROS，仍会发生细胞凋亡。
