Nrf2 signaling attenuates epithelial-to-mesenchymal transition and renal interstitial fibrosis via PI3K/Akt signaling pathways

• Published in: Experimental and molecular pathology Vol. 111; p. 104296
• Main Authors: Wang, Jun, Zhu, Haobo, Huang, Liqu, Zhu, Xiaojiang, Sha, Jintong, Li, Guogen, Ma, Geng, Zhang, Wei, Gu, Min, Guo, Yunfei
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.12.2019
• Subjects: Animals; Cadherins - genetics; Cadherins - metabolism; Disease Models, Animal; Epithelial-Mesenchymal Transition; Epithelial-to-mesenchymal transition; Fibronectins - genetics; Fibronectins - metabolism; Fibrosis - etiology; Fibrosis - metabolism; Fibrosis - pathology; Fibrosis - prevention & control; Kidney Diseases - etiology; Kidney Diseases - metabolism; Kidney Diseases - pathology; Kidney Diseases - prevention & control; Kidney fibrosis; Mice; Mice, Knockout; NF-E2-Related Factor 2 - physiology; Nrf2; Phosphatidylinositol 3-Kinases - genetics; Phosphatidylinositol 3-Kinases - metabolism; Proto-Oncogene Proteins c-akt - genetics; Proto-Oncogene Proteins c-akt - metabolism; Signal Transduction; Transforming Growth Factor beta1 - genetics; Transforming Growth Factor beta1 - metabolism; Ureteral Obstruction - etiology; Ureteral Obstruction - metabolism; Ureteral Obstruction - pathology; Ureteral Obstruction - prevention & control; Nrf2; Epithelial-to-mesenchymal transition; Kidney fibrosis
• DOI: 10.1016/j.yexmp.2019.104296
• ISSN: 0014-4800; 1096-0945

Nrf2 constitutes a therapeutic reference point for renal fibrosis and chronic kidney diseases. Nrf2-related signaling pathways are recognized to temper endothelial-to-mesenchymal transition (EMT) in fibrotic tissue. Nevertheless, the mechanism by which Nrf2 mitigates renal interstitial fibrosis is imprecise. The relationship between Nrf2 and renal interstitial fibrosis was investigated using the unilateral ureteral obstruction (UUO) model of Nrf2−/− mice. The mice were separated into four groups, based on the treatment and intervention: Nrf2−/− + UUO, Nrf2−/− + Sham, WT + UUO and WT + Sham. Histological examination of renal tissue following the hematoxylin-eosin and Masson staining was carried out, as well as immunohistochemical staining. Additionally, to confirm the in vivo discoveries, in vitro experiments with HK-2 cells were also performed. The Nrf2−/− + UUO group showed more severe renal interstitial fibrosis compared to the WT + UUO, Nrf2−/− + Sham and WT + Sham groups. Furthermore, the manifestations of α-SMA and Fibronectin significantly increased, and the manifestation of E-cadherin considerably decreased in kidney tissues from the group of Nrf2−/− + UUO, compared to the WT + UUO group. The Nrf2 protein level significantly decreased in HK-2 cells, in reaction to the TGF-β1 concentration. In addition, the overexpression of Nrf2 presented contradictory results. What is more, the PI3K/Akt signaling pathway was discovered to be activated in the proteins extracted from cultured cells, and treated with Nrf2 siRNA and kidney tissues from the Nrf2−/− + UUO group. The results we obtained demonstrate that Nrf2 signaling pathway may perhaps offset the development of EMT, prompted by TGF-β1 and renal interstitial fibrosis. Likewise, the anti-fibrotic effect of Nrf2 was imparted by the inactivation of PI3K/Akt signaling. From our discoveries, we deliver new insight related to the prevention and treatment of kidney fibrosis.