p53/microRNA-214/ULK1 axis impairs renal tubular autophagy in diabetic kidney disease
Zhengwei Ma, Lin Li, Man J. Livingston, Dongshan Zhang, Qingsheng Mi, Ming Zhang, Han-Fei Ding, Yuqing Huo, Changlin Mei, Zheng Dong
Zhengwei Ma, Lin Li, Man J. Livingston, Dongshan Zhang, Qingsheng Mi, Ming Zhang, Han-Fei Ding, Yuqing Huo, Changlin Mei, Zheng Dong
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Research Article Nephrology

p53/microRNA-214/ULK1 axis impairs renal tubular autophagy in diabetic kidney disease

Abstract

Dysregulation of autophagy in diabetic kidney disease (DKD) has been reported, but the underlying mechanism and its pathogenic role remain elusive. We show that autophagy was inhibited in DKD models and in human diabetic kidneys. Ablation of autophagy-related gene 7 (Atg7) from kidney proximal tubules led to autophagy deficiency and worse renal hypertrophy, tubular damage, inflammation, fibrosis, and albuminuria in diabetic mice, indicating a protective role of autophagy in DKD. Autophagy impairment in DKD was associated with the downregulation of unc-51–like autophagy-activating kinase 1 (ULK1), which was mediated by the upregulation of microRNA-214 (miR-214) in diabetic kidney cells and tissues. Ablation of miR-214 from kidney proximal tubules prevented a decrease in ULK1 expression and autophagy impairment in diabetic kidneys, resulting in less renal hypertrophy and albuminuria. Furthermore, blockade of p53 attenuated miR-214 induction in DKD, leading to higher levels of ULK1 and autophagy, accompanied by an amelioration of DKD. Compared with nondiabetic samples, renal biopsies from patients with diabetes showed induction of p53 and miR-214, associated with downregulation of ULK1 and autophagy. We found a positive correlation between p53/miR-214 and renal fibrosis, but a negative correlation between ULK1/LC3 and renal fibrosis in patients with diabetes. Together, these results identify the p53/miR-214/ULK1 axis in autophagy impairment in diabetic kidneys, pinpointing possible therapeutic targets for DKD.

Authors

Zhengwei Ma, Lin Li, Man J. Livingston, Dongshan Zhang, Qingsheng Mi, Ming Zhang, Han-Fei Ding, Yuqing Huo, Changlin Mei, Zheng Dong

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Figure 8

p53 is activated in diabetic kidneys to induce miR-214 for ULK1 and autophagy suppression.

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p53 is activated in diabetic kidneys to induce miR-214 for ULK1 and auto...
(A) p53 induction in kidney tubule cells of STZ-treated diabetic mice shown by IHC staining. C57BL/6 mice were treated with STZ or control vehicle solution and examined 11 weeks later for p53 IHC. Arrowheads indicate p53-positive nuclei. Scale bar: 0.1 mm. (B) Immunoblots showing p53 and its phosphorylation induced by HG in RPTCs. RPTCs were incubated with 5.5 mM NG (CT) or 30 mM HG for 24 hours to collect lysate for immunoblot analysis. (C and D) Inhibition of ULK1 and LC3 decreases in HG-treated RPTCs by pifithrin-α. RPTCs were incubated with NG or 30 mM HG in the absence or presence of 5 μΜ pifithrin-α for 24 hours to collect whole-cell lysate for immunoblot analysis. (E) Inhibitory effect of pifithrin-α on miR-214 induction during HG incubation shown by real-time PCR analysis (n = 4; 1-way ANOVA with Tukey’s multiple comparisons test). (F) miR-214 promoter region harboring the p53 binding site. (G) ChIP assay of p53 binding to the miR-214 promoter sequence during HG incubation. BUMPT cells were treated with 5.5 mM (control) or 30 mM (HG) glucose for 24 hours for the ChIP assay using anti-p53 antibody (n = 4; 2-tailed Student’s t test). The values were normalized to that for the control group, which was arbitrarily set at 1. *P < 0.05.