FC 133: Knockout Of ZEB2 Ameliorates Progression of Renal Tubulointerstitial Fibrosis in a Mouse Model of Renal Ischemia-Reperfusion Injury

Abstract

Abstract BACKGROUND AND AIMS Zeb2, a zinc finger E-box-binding homeobox transcription factor, reportedly regulates transforming growth factor (TGF)-β signaling pathway. However, its role in the pathogenesis of acute kidney injury (AKI) and AKI to chronic kidney disease (CKD) transition is unclear. METHOD We evaluated Zeb2 function in a bilateral renal ischemia-reperfusion injury (IRI)-induced AKI model using proximal tubule-specific Zeb2 conditional knockout (Zeb2-cKO) and wild-type (WT) mice. In Zeb2-cKO mice, plasma creatinine and blood urea nitrogen levels post-IRI were significantly lower than those in WT mice. Immunohistological analysis revealed mild tubular injury, less fibrotic changes, and reduced expression of fibrotic proteins, such as collagen type IV, α-smooth muscle actin (α-SMA), fibronectin and connective tissue growth factor (CTGF), at 3–14 days post-IRI in Zeb2-cKO mice. We also evaluated Zeb2 expression in human renal biopsy samples, including AKI to CKD patients, by immunohistological methods. RESULTS Zeb2 expression was mainly upregulated in proximal tubular cells post-IRI in WT mice. Zeb2 siRNA transfection reduced TGF-β-stimulated mRNA and protein expression of collagen type IV, α-SMA, fibronectin and CTGF in cultured renal tubular cells. Notably, patients with AKI to CKD transition showed high Zeb2 expression in renal tubules, as determined by evaluation of their renal biopsy samples. Furthermore, hypoxia and CoCl2-treatment upregulated Zeb2 promoter activity and mRNA and protein expression in cultured renal tubular epithelial cells, suggesting regulatory role of hypoxia. CONCLUSION Thus, we demonstrated Zeb2 upregulation in renal tissues in both mice and humans with AKI and showed that Zeb2 regulates fibrotic pathways in pathogenesis of AKI and AKI to CKD transition. Our findings suggest that Zeb2 blockage could serve as a potential therapeutic strategy in AKI.