Quercetin as a Novel Treatment for Developmental Abnormalities of the Kidney

Abstract

Renal dysplasia is the abnormal development of the kidney and is the leading cause of chronic kidney disease and kidney failure in children. Despite this, there is no cure. Invasive symptom management such as dialysis and kidney transplants have significant adverse effects. Normal kidney development involves the interaction between three cell types: ureteric epithelium, metanephric mesenchyme, and renal stroma. The ureteric epithelium undergoes branching morphogenesis to form the collecting system, and the metanephric mesenchyme undergoes nephrogenesis to form the nephrons. The renal stroma provides structural support to the developing kidney and regulates proper branching morphogenesis and nephrogenesis. Beta‐catenin is a transcription factor essential for normal branching morphogenesis and nephrogenesis. In human renal dysplasia, beta‐catenin levels are markedly increased in the nucleus of the stroma, mesenchyme and epithelium. Our findings from transgenic mouse models show that elevated levels of beta‐catenin in the nucleus cause dysregulation of genes leading to abnormal branching morphogenesis and nephrogenesis, resulting in renal dysplasia. Our objective is to inhibit beta‐catenin transcriptional activity in the kidney and determine its effects on normal and dysplastic kidney development. Quercetin is a flavonoid that inhibits beta‐catenin activity and was effective in reducing beta‐catenin levels that resulted to improved outcomes in different cancer types and in kidney fibrosis. We tested if Quercetin alters beta‐catenin activity during normal kidney development. Wild‐type embryonic day 13.5 mouse kidneys were cultured in growth medium supplemented with 0uM (control), 40uM, 80uM, and 160uM Quercetin for 48 hours. A dose‐dependent disruption in branching morphogenesis and nephrogenesis was observed by performing immunofluorescence for cytokeratin, Pax2, and Six2. In addition, quantitative reverse‐transcriptase PCR (qRT‐PCR) showed a disrupted expression of beta‐catenin target genes essential for kidney development (Pax2, Wnt4, and GDNF). Consistent with these findings, immunohistochemistry for beta‐catenin demonstrated that Quercetin reduced nuclear beta‐catenin expression and increased cytoplasmic expression in a dose‐dependent manner. Next, to determine if Quercetin rescues renal dysplasia, we utilized transgenic mice models that over‐express beta‐catenin specifically in the kidney stroma (Foxd1;B‐catGOFs), or in the mesenchyme, stroma, and ureteric epithelium (Rarb2;B‐catGOFsmu). Both of these animal models have severe renal dysplasia characterized by disorganized branching morphogenesis and disrupted nephrogenesis. Immunofluorescence for cytokeratin and Pax2 showed that in‐vitro treatment of embryonic day 13.5 dysplastic kidneys with 40uM Quercetin resulted in a markedly improved kidney with improved branching morphogenesis and nephrogenesis, and closely resembles wild‐type kidney development. Our findings demonstrate that Quercetin reduces beta‐catenin activity in normal and dysplastic kidneys, reduces the transcription of genes that play central roles in kidney development, and resulted to a reduced severity of renal dysplasia.Support or Funding InformationNSERC, CIHR and KFOCThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.