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Abstract: FR-PO086

Nrf2 Attenuates Tubular Epithelia Cell Transdifferentiation in Response to Hypoxia Through Regulating CTGF Secretion

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Kong, Weiwei, The Affiliated Shengjing Hospital of China Medical School, Shenyang/China, LIAONING, China
  • Fu, Jingqi, The Affiliated Shengjing Hospital of China Medical School, Shenyang/China, LIAONING, China
  • Luan, Junjun, The Affiliated Shengjing Hospital of China Medical School, Shenyang/China, LIAONING, China
  • Jiao, Congcong, The Affiliated Shengjing Hospital of China Medical School, Shenyang/China, LIAONING, China
  • Qi, Huimeng, China Medical University, Shenyang, China
  • Wang, Yanqiu, The Affiliated Shengjing Hospital of China Medical School, Shenyang/China, LIAONING, China
  • Li, Detian, The Affiliated Shengjing Hospital of China Medical School, Shenyang/China, LIAONING, China
  • Pi, Jingbo, China Medical University, Shenyang, China
  • Zhou, Hua, The Affiliated Shengjing Hospital of China Medical School, Shenyang/China, LIAONING, China
Background

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a well-known regulator of oxidant and xenobiotic metabolism. We previously reported that Nrf2 ameliorates renal tubular transdifferentiation in mice on day 5 after unilateral ureteral obstruction (UUO); however, the mechanism of attentuation remains unclear. We aimed to clarify whether Nrf2 regulates the connective tissue growth factor (CTGF)/WNT pathway, which is a key pathway in tubular epithelia cell transdifferentiation.

Methods

Normal rat kidney-52E (NRK52E) tubular cells were divided into four groups: scramble control, Nrf2-knockdown (Nrf2-KD) control, scramble hypoxia (5%), and Nrf2-KD hypoxia groups. Expression levels of CTGF and WNT signaling pathway (p-Lrp6 and β-catenine) were detected by western blotting. Then, we used siRNAs to silence CTGF and Nrf2 simultaneously and to measure WNT signaling and vimentin, a transdifferentiation marker. We also investigated the expression of c-fos, a known transcription regulator of CTGF, and the expression of a group microRNAs as post transcription factors of CTGF. In addition, we evaluated the expression of CTGF in the kidneys of Nrf2+/+ and Nrf2−/− mice 5 days after UUO by immunostaining and western blotting.

Results

We found that Nrf2 deletion significantly increased CTGF expression in response to 5% of hypoxia in NRK52E cell line. In hypoxia treated NRK52E cells, deletion of Nrf2 promoted expression of p-Lrp6 and β-catenine as well as vimentin. The overexpression of p-Lrp6, β-catenine and vimentin due to only silencing Nrf2 was decreased by double silencing Nrf2 and CTGF. Nrf2 knockdown increased expression of c-fos and p-c-fos in NRK52E cells. However, Nrf2 knockdown showed no regulation of post-transcription factors such as miR-26a, miR-26b, miR-30a and miR-133. Similarly, expression of CTGF and activity of WNT signaling were increased in Nrf2−/− mice compared to those in Nrf2+/+ mice on the 5th day after UUO operation.

Conclusion

Nrf2 attenuated tubular epithelial cellular transdifferntiation may be mediated by downregulating WNT signaling pathway through inhibiting CTGF secretion in tubular epithelial cells. This suggests that Nrf2 activator might be a potential agent to slow down the progression from acute renal tubular damage to chronic tubulointerstitial fibrosis.

Funding

  • Government Support - Non-U.S.