School of Life Sciences and Biotechnology, College of Natural Sciences, Kyungpook National University, Taegu 702-701, Republic of Korea.
Biochem Pharmacol. 2010 Apr 1;79(7):1072-80. doi: 10.1016/j.bcp.2009.11.014. Epub 2009 Nov 26.
Cadmium ions have a high affinity for thiol groups. Therefore, they may disturb many cellular functions. We recently reported that cytosolic NADP(+)-dependent isocitrate dehydrogenase (IDPc) functions as an antioxidant enzyme to supply NADPH, a major source of reducing equivalents to the cytosol. Cadmium decreased the activity of IDPc both as a purified enzyme and in cultured cells. In the present study, we demonstrate that the knockdown of IDPc expression in HEK293 cells greatly enhances apoptosis induced by cadmium. Transfection of HEK293 cells with an IDPc small interfering RNA significantly decreased the activity of IDPc and enhanced cellular susceptibility to cadmium-induced apoptosis as indicated by the morphological evidence of apoptosis, DNA fragmentation and condensation, cellular redox status, mitochondria redox status and function, and the modulation of apoptotic marker proteins. Taken together, our results suggest that suppressing the expression of IDPc enhances cadmium-induced apoptosis of HEK293 cells by increasing disruption of the cellular redox status.
镉离子对巯基基团具有高亲和力。因此，它们可能会干扰许多细胞功能。我们最近报道，细胞质 NADP(+)-依赖性异柠檬酸脱氢酶 (IDPc) 作为抗氧化酶发挥作用，为细胞质提供 NADPH，这是还原当量的主要来源。镉既降低了纯化酶的 IDPc 活性，也降低了培养细胞中的 IDPc 活性。在本研究中，我们证明了在 HEK293 细胞中敲低 IDPc 表达会大大增强镉诱导的细胞凋亡。用 IDPc 小干扰 RNA 转染 HEK293 细胞会显著降低 IDPc 的活性，并增强细胞对镉诱导的凋亡的敏感性，这表现在凋亡的形态学证据、DNA 片段化和浓缩、细胞氧化还原状态、线粒体氧化还原状态和功能以及凋亡标记蛋白的调节。总之，我们的结果表明，通过增加细胞氧化还原状态的破坏，抑制 IDPc 的表达会增强镉诱导的 HEK293 细胞凋亡。
