Transcriptional profiling of Wnt4 mutant mouse kidneys identifies genes expressed during nephron formation

Abstract

The mature nephron forms from a simple epithelial vesicle into an elaborate structure with distinct regions of specialized physiological function. The molecular components driving the process of nephron development are not well understood. To identify genes that may be informative in this process we conducted a transcriptional profiling screen using Wnt4 mutant kidneys. In Wnt4 −/− homozygous mice, condensates and pretubular aggregates are induced, however, epithelial renal vesicles fail to form and subsequent tubulogenesis is blocked. A transcriptional profile comparison between wildtype and Wnt4−/− mutant kidneys at E14.5 was performed using Affymetrix oligonucleotide microarrays to identify nephron-expressed genes. This approach identified 236 genes with expression levels >1.8 fold higher in wildtype versus mutant kidneys, amongst these were a number of known nephron component markers confirming the validity of the screen. These results were further detailed by wholemount in situ hybridization (WISH) of E15.5 urogenital systems (UGS). We annotated the spatial expression pattern of these genes into eight categories of expression. Genes expressed in renal vesicle and their derivatives, structures absent in the mutant, accounted for the largest number of the observed expression patterns. A number of additional genes in areas not directly overlapping the Wnt4 expression domain were also identified including the cap mesenchyme, the collecting duct, and the cortical interstitium. This study provides a useful compendium of molecular markers for the study of nephrogenesis.

Identification of ptpro as a novel target gene of Wnt signaling and its potential role as a receptor for Wnt

“…We showed that the levels of both the mRNA and protein of ptpro were increased by Wnt/b-catenin signaling. Consistent with this finding, it has been shown that the expression of ptpro is reduced 12-fold in the kidney of Wnt4 knockout mice [20]. In addition, ChIP and reporter assays suggested that the increased expression of ptpro was mediated by Tcf/Lef1.…”

Characterization of mesonephric development and regeneration using transgenic zebrafish

“…De novo intrarenal ANG II production is known to increase because of renal insufficiency following experimental nephrectomy (7) and during renal disease (14) or in response to chronic peripheral ANG II infusion (23). Additionally, RAS signaling, partially mediated by Wnt4 induction of ACE in the metanephric cap mesenchyme (21,26), is required for normal metanephric nephron development (10) and ANG II has been demonstrated to lie upstream of many growth factors and transcription factors required for normal kidney development (30,31). Finally, it is noteworthy that ANG II is able to induce the proliferation of hematopoietic progenitor cells (HPC) isolated from murine bone marrow or human cord blood (21), suggesting its role in regulating stem cells.…”

Gudmap

“…Analysis of their expression showed that half are restricted to Wnt4-dependent structures. 13 Thus, the screen significantly enriches for genes that demarcate the target component of the kidney. In both instances, accompanying WISH and SISH of the resultant gene lists acts both to validate the data and to identify novel subcompartments of the structures initially profiled, thereby expanding our developmental ontology to include domains that are identifiable only via gene expression.…”