Chen Cheng-Lung, Liao Jiunn-Wang, Hu Oliver Yoa-Pu, Pao Li-Heng
Graduate Institute of Life Sciences, National Defense Medical Center, No. 161, Sec. 6, Minquan E. Rd., Neihu Dist., Taipei, Taiwan, R.O.C.
Graduate Institute of Veterinary Pathology, National Chung Hsing University, No. 250, Guoguang Rd., South Dist., Taichung, Taiwan, R.O.C.
Arch Toxicol. 2016 Sep;90(9):2249-2260. doi: 10.1007/s00204-015-1607-5. Epub 2015 Oct 5.
Tubular cell apoptosis significantly contributes to cisplatin-induced acute kidney injury (AKI) pathogenesis. Although KCa3.1, a calcium-activated potassium channel, participates in apoptosis, its involvement in cisplatin-induced AKI is unknown. Here, we found that cisplatin treatment triggered an early induction of KCa3.1 expression associated with HK-2 cell apoptosis, the development of renal tubular damage, and apoptosis in mice. Treatment with the highly selective KCa3.1 blocker TRAM-34 suppressed cisplatin-induced HK-2 cell apoptosis. We further assessed whether KCa3.1 mediated cisplatin-induced AKI in genetic knockout and pharmacological blockade mouse models. KCa3.1 deficiency reduced renal function loss, renal tubular damage, and the induction of the apoptotic marker caspase-3 in the kidneys of cisplatin-treated KCa3.1 (-/-) mice. Pharmacological blockade of KCa3.1 by TRAM-34 similarly attenuated cisplatin-induced AKI in mice. Furthermore, we dissected the mechanisms underlying cisplatin-induced apoptosis reduction via KCa3.1 blockade. We found that KCa3.1 blockade attenuated cytochrome c release and the increase in the intrinsic apoptotic mediators Bax, Bak, and caspase-9 after cisplatin treatment. KCa3.1 blocking inhibited the cisplatin-induced activation of the endoplasmic reticulum (ER) stress mediator caspase-12, which is independent of calcium-dependent protease m-calpain activation. Taken together, KCa3.1 blockade protects against cisplatin-induced AKI through the attenuation of apoptosis by interference with intrinsic apoptotic and ER stress-related mediators, providing a potential target for the prevention of cisplatin-induced AKI.
肾小管细胞凋亡在顺铂诱导的急性肾损伤（AKI）发病机制中起重要作用。尽管钙激活钾通道KCa3.1参与细胞凋亡，但其在顺铂诱导的AKI中的作用尚不清楚。在此，我们发现顺铂处理可触发KCa3.1表达的早期诱导，这与HK-2细胞凋亡、肾小管损伤的发展以及小鼠体内的细胞凋亡有关。用高选择性KCa3.1阻滞剂TRAM-34处理可抑制顺铂诱导的HK-2细胞凋亡。我们进一步在基因敲除和药物阻断小鼠模型中评估了KCa3.1是否介导顺铂诱导的AKI。KCa3.1缺陷减少了顺铂处理的KCa3.1（-/-）小鼠肾脏中的肾功能损失、肾小管损伤以及凋亡标志物caspase-3的诱导。TRAM-34对KCa3.1的药物阻断同样减轻了小鼠顺铂诱导的AKI。此外，我们剖析了通过KCa3.1阻断减少顺铂诱导的细胞凋亡的机制。我们发现KCa3.1阻断减弱了顺铂处理后细胞色素c的释放以及内源性凋亡介质Bax、Bak和caspase-9的增加。KCa3.1阻断抑制了顺铂诱导的内质网（ER）应激介质caspase-12的激活，这与钙依赖性蛋白酶m-钙蛋白酶的激活无关。综上所述，KCa3.1阻断通过干扰内源性凋亡和ER应激相关介质来减轻细胞凋亡，从而保护机体免受顺铂诱导的AKI，为预防顺铂诱导的AKI提供了一个潜在靶点。
