RESUMO
Objective To investigate the role and mechanism of spliced X-box binding protein 1 (XBP1s) in the senescence of primary renal tubular epithelial cells induced by hypoxia/reoxygenation (H/R). Methods Primary renal tubular epithelial cells were divided into the normal control group (NC group), H/R group, empty adenovirus negative control group (Ad-shNC group), targeted silencing XBP1s adenovirus group (Ad-shXBP1s group), empty adenovirus+H/R treatment group (Ad-shNC+H/R group) and targeted silencing XBP1s adenovirus+H/R treatment group (Ad-shXBP1s +H/R group), respectively. The expression levels of XBP1s in the NC, H/R, Ad-shNC and Ad-shXBP1s groups were measured. The number of cells stained with β-galactosidase, the expression levels of cell aging markers including p53, p21 and γH2AX, and the levels of reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) were determined in the Ad-shNC, Ad-shNC+H/R and Ad-shXBP1s+H/R groups. Chromatin immunoprecipitation was employed to verify Sirtuin 3 (Sirt3) of XBP1s transcription regulation, and the expression levels of Sirt3 and downstream SOD2 after down-regulation of XBP1s were detected. Mitochondrial reactive oxygen species (mtROS) were detected by flow cytometry. Results Compared with the NC group, the expression level of XBP1s was up-regulated in the H/R group. Compared with the Ad-shNC group, the expression level of XBP1s was down-regulated in the Ad-shXBP1s group (both P<0.001). Compared with the Ad-shNC group, the number of cells stained with β-galactosidase was increased, the expression levels of p53, p21 and γH2AX were up-regulated, the levels of ROS, MDA and mtROS were increased, the SOD activity was decreased, the expression level of Sirt3 was down-regulated, and the ratio of Ac-SOD2/SOD2 was increased in the Ad-shNC+H/R group. Compared with the Ad-shNC+H/R group, the number of cells stained with β-galactosidase was decreased, the expression levels of p53, p21 and γH2AX were down-regulated, the levels of ROS, MDA and mtROS were decreased, the SOD activity was increased, the expression level of Sirt3 was up-regulated and the ratio of Ac-SOD2/SOD2 was decreased in the Ad-shXBP1s+H/R group (all P<0.05). Conclusions Down-regulation of XBP1s may ameliorate the senescence of primary renal tubular epithelial cells induced by H/R, which probably plays a role through the Sirt3/SOD2/mtROS signaling pathway.