Article

c-Myc promotes tubular cell apoptosis in ischemia-reperfusioninduced renal injury by negatively regulating c-FLIP and enhancing FasL/Fas-mediated apoptosis pathway

Authors: Dan Xu1, Bao Wang1, Pan-pan Chen1, Yan-zhe Wang2, Nai-jun Miao1, Fan Yin1, Qian Cheng1, Zhuan-li Zhou1, Hong-yan Xie1, Li Zhou1, Jun Liu1, Xiao-xia Wang2, Hong Xue1, Wei Zhang1, Li-min Lu1
1 Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
2 Department of Nephrology, Shanghai Tong Ren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200032, China
Correspondence to: Hong Xue: xuehong@fudan.edu.cn, Wei Zhang: wzhang@shmu.edu.cn, Li-min Lu: lulimin@shmu.edu.cn,
DOI: 10.1038/s41401-018-0201-9
Received: 3 September 2018
Accepted: 29 November 2018
Advance online: 28 December 2018

Abstract

c-Myc plays an important role in cell proliferation, differentiation, and cell apoptosis. FasL/Fas pathway is a key regulator of cell apoptosis. This study was aimed to investigate the effects of c-Myc on the FasL/Fas pathway in ischemia-reperfusion (I/R)-induced renal injury. Rats were objected to bilateral renal ischemia for 60 min and reperfused for 24 or 48 h. NRK-52E cells were treated with hypoxia-reoxygenation (H/R) or FasL. Immunohistochemistry was used to identify the distribution of c-Myc. Cell apoptosis was assessed by TUNEL staining. Ad-c-Myc and recombinant pcDAN 3.0 were used to overexpress c-Myc and c-FLIP, respectively. ChIP assay and luciferase assay were used to detect the binding of c-Myc to c-FLIP promoter. In I/R rats, c-Myc was increased significantly and mainly located in renal tubular epithelial cells; meanwhile, c-FLIP was decreased, cleaved caspase-8, cleaved caspase-3 and TUNEL-positive staining cells were increased. Treatment of I/R rats with c-Myc inhibitor 10058-F4 significantly attenuated the decrease in c-FLIP, the increase in cleaved caspase-8, cleaved caspase-3, TUNEL-positive cells, Scr and BUN in I/R rats. In NRK-52E cells, hypoxia and reoxygen induced the increase in c-Myc and decrease in c-FLIP. ChIP and luciferase assay results indicated that c-Myc binds to the promoter region of c-FLIP gene. Overexpression of c-Myc markedly decreased c-FLIP. Overexpression of c-FLIP inhibited the increase in cleaved caspase-8 and caspase-3 induced by FasL. Data indicated that c-Myc is increased in kidneys of I/R rats and negatively regulates the expression of c-FLIP, then enhanced FasL-induced cell apoptosis in I/R stress.
Keywords: c-Myc; c-FLIP; FasL/Fas; ischemia-reperfusion; tubular cell apoptosis

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