ZEB2 signaling is essential for ureteral smooth muscle cell differentiation and maintenance

Mowat-Wilson Syndrome (MWS) is a multiple congenital anomaly syndrome caused by mutations in the <i>ZEB2,</i> which plays a critical role in cell fate determination and differentiation during development. Congenital anomalies of the kidney and urinary tract (CAKUT) have been reported in MWS patients. However, the role of ZEB2 in urinary tract development and the cellular and molecular mechanism underlining the CAKUT phenotypes in MWS remains unknown. We performed ZEB2 protein expression analysis in the developing mouse ureter. We generated <i>Zeb2</i> ureteral mesenchyme-specific conditional knockout mice by crossing <i>Zeb2</i> floxed mice with Tbx18Cre mice (<i>Zeb2</i> cKO) and analyzed the urinary tract phenotypes in <i>Zeb2</i> cKO mice and wild-type littermate controls by gross and histological examination. Ureteral cellular and molecular phenotypes were studied using TAGLN, ACTA2, FOXD1, POSTN, CDH1, TBX18, and SOX9 ureteral cell-specific markers. We found that ZEB2 is expressed in TBX18⁺ ureteral mesenchymal cells during mouse ureter development. Deletion of <i>Zeb2</i> in developing ureteral mesenchymal cells causes hydroureter and hydronephrosis phenotypes, leading to obstructive uropathy, kidney failure, and early mortality. Cellular and molecular marker analyses showed that the TAGLN⁺ACTA2⁺ ureteral smooth muscle cells (SMCs) layer is not formed in <i>Zeb2</i> cKO mice at E15.5, but the FOXD1⁺ and POSTN⁺ tunica adventitia cells layer is significantly expanded compared to wild-type controls. CDH1⁺ urothelium cells are reduced considerably in the <i>Zeb2</i> cKO ureters at E15.5. Mechanistically, we found that <i>Zeb2</i> cKO mice have significantly decreased TBX18 expression but an increased SOX9 expression in the developing ureter at E14.5 and E15.5 compared to wild-type littermate controls. Our results show that ZEB2 is essential for ureter development by maintaining ureteral mesenchymal cell differentiation into normal ureteral SMCs. Our study also shed new light on the pathological mechanism underlying the developmental abnormalities of the urinary tract phenotypes in MWS patients.