A mouse model of early-onset renal failure due to a xanthine dehydrogenase nonsense mutation.

Sian E Piret,Caroline M Gorvin,Matthew Brown,Olivier Devuyst,Rajesh V Thakker,Gethin Thomas,Roger Cox,Peter Croucher,Nellie Y Loh,Rosie Head,Christopher T Esapa,Steve D M Brown

doi:10.1371/journal.pone.0045217

Abstract

Chronic kidney disease (CKD) is characterized by renal fibrosis that can lead to end-stage renal failure, and studies have supported a strong genetic influence on the risk of developing CKD. However, investigations of the underlying molecular mechanisms are hampered by the lack of suitable hereditary models in animals. We therefore sought to establish hereditary mouse models for CKD and renal fibrosis by investigating mice treated with the chemical mutagen N-ethyl-N-nitrosourea, and identified a mouse with autosomal recessive renal failure, designated RENF. Three-week old RENF mice were smaller than their littermates, whereas at birth they had been of similar size. RENF mice, at 4-weeks of age, had elevated concentrations of plasma urea and creatinine, indicating renal failure, which was associated with small and irregularly shaped kidneys. Genetic studies using DNA from 10 affected mice and 91 single nucleotide polymorphisms mapped the Renf locus to a 5.8Mbp region on chromosome 17E1.3. DNA sequencing of the xanthine dehydrogenase (Xdh) gene revealed a nonsense mutation at codon 26 that co-segregated with affected RENF mice. The Xdh mutation resulted in loss of hepatic XDH and renal Cyclooxygenase-2 (COX-2) expression. XDH mutations in man cause xanthinuria with undetectable plasma uric acid levels and three RENF mice had plasma uric acid levels below the limit of detection. Histological analysis of RENF kidney sections revealed abnormal arrangement of glomeruli, intratubular casts, cellular infiltration in the interstitial space, and interstitial fibrosis. TUNEL analysis of RENF kidney sections showed extensive apoptosis predominantly affecting the tubules. Thus, we have established a mouse model for autosomal recessive early-onset renal failure due to a nonsense mutation in Xdh that is a model for xanthinuria in man. This mouse model could help to increase our understanding of the molecular mechanisms associated with renal fibrosis and the specific roles of XDH and uric acid.

Highlights

Chronic kidney disease (CKD) is a major health problem worldwide
Single nucleotide polymorphisms (SNPs) within the myosin heavy chain type II isoform A (MYH9)-Apolipoprotein L1 (APOL1) gene region were found to be associated with end stage renal failure (ESRF) in African Americans [2,3], whilst several associations have been identified between single nucleotide polymorphisms (SNPs) and CKD or markers of decreased renal function, such as SNPs near genes involved in nephrogenesis, e.g. ALMS1, or solute transport, e.g. SLC7A9, that were associated with CKD [4]
Post mortem analysis undertaken at 4 weeks of age revealed that kidneys from RENF mice were smaller, irregularly shaped and had a fatty appearance when compared to kidneys from unaffected littermates (Figure 1C)

Summary

Introduction

Chronic kidney disease (CKD) is a major health problem worldwide. Due to its progressive nature, patients with CKD are at risk of developing cardiovascular disease and end stage renal failure (ESRF), often in association with secondary hyperparathyroidism. Some genes identified as associated with CKD in the general population by GWAS, such as UMOD that encodes uromodulin, can cause monogenic renal disorders due to rare pathogenic mutations [4,5]; both GWAS and studies of monogenic inherited diseases can help to elucidate important biological pathways. Further investigations of the underlying genetic and molecular mechanisms of CDK have been hampered by the lack of suitable hereditary models in animals To facilitate such studies, we embarked on establishing mouse models for renal fibrosis and CKD by investigating the phenotypes of progeny of mice treated with the chemical mutagen N-ethyl-N-nitrosourea (ENU). ENU mutagenesis has generated a variety of mouse models, including dominant and recessive, hypo- and hypermorphs, for different diseases including renal disorders, such as Catweasel mice, which are a model for branchio-oto-renal syndrome due to a hypomorphic mutation in Six1 [7]. We report studies of one of the models which was identified during an ENU screen, designated RENF (Renal Failure), which is a mouse model for autosomal recessive early-onset renal failure

Methods

Results

Conclusion