KMID : 1102220240430020186
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Kidney Research and Clinical Practice 2024 Volume.43 No. 2 p.186 ~ p.201
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Role of APE1/Ref-1 in hydrogen peroxide-induced apoptosis in human renal HK-2 cells
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Kim Ha-Yeon
Park Jung-Sun Jeon Byeong- Hwa Choi Hong-Sang Kim Chang-Seong Ma Seong-Kwon Kim Soo-Wan Bae Eun-Hui
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Abstract
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Background: Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) is a multipotent protein that plays essential roles in cellular responses to oxidative stress.
Methods: To examine the role of APE1/Ref-1 in ischemia-reperfusion (I/R) injuries and hydrogen peroxide (H2O2)-induced renal tubular apoptosis, we studied male C57BL6 mice and human proximal tubular epithelial (HK-2) cells treated with H2O2 at different concentrations. The colocalization of APE1/Ref-1 in the proximal tubule, distal tubule, thick ascending limb, and collecting duct was observed with confocal microscopy. The overexpression of APE1/Ref-1 with knockdown cell lines using an APE1/Ref-1?specific DNA or small interfering RNA (siRNA) was used for the apoptosis assay. The promotor activity of nuclear factor kappa B (NF-¥êB) was assessed and electrophoretic mobility shift assay was conducted.
Results: APE1/Ref-1 was predominantly localized to the renal tubule nucleus. In renal I/R injuries, the levels of APE1/Ref-1 protein were increased compared with those in kidneys subjected to sham operations. The overexpression of APE1/Ref-1 in HK-2 cells enhanced the Bax/Bcl-2 ratio as a marker of apoptosis. Conversely, the suppression of APE1/Ref-1 expression by siRNA in 1-mM H2O2-treated HK-2 cells decreased the Bax/Bcl-2 ratio, the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, p38, c-Jun N-terminal kinase (JNK) 1/2, and NF-¥êB. In HK-2 cells, the promoter activity of NF-¥êB increased following H2O2 exposure, and this effect was further enhanced by APE1/Ref-1 transfection.
Conclusion: The inhibition of APE1/Ref-1 with siRNA attenuated H2O2-induced apoptosis through the modulation of mitogen-activated protein kinase pathways mediated by ERK, JNK, and p38 and the nuclear activation of NF-¥êB and proapoptotic factors.
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KEYWORD
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APE1/Ref-1, APE1/Ref-1 inhibitor, Apoptosis, HK-2 cells, Reperfusion injury
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