MP23-12 GENOME-WIDE MAPPING OF WT1 TARGET GENES REVEALS MOLECULAR MECHANISMS OF WT1 IN NEPHROGENESIS AND WILMS’ TUMOR

Abstract

You have accessJournal of UrologyKidney Cancer: Basic Research I1 Apr 2014MP23-12 GENOME-WIDE MAPPING OF WT1 TARGET GENES REVEALS MOLECULAR MECHANISMS OF WT1 IN NEPHROGENESIS AND WILMS’ TUMOR Eunah Chung and Joo-Seop Park Eunah ChungEunah Chung More articles by this author and Joo-Seop ParkJoo-Seop Park More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.880AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The Wt1 gene encodes a transcription factor that not only prevents Wilms’ tumor formation but also plays an important role in nephrogenesis. At an early step in nephrogenesis, mesenchymal nephron progenitors become epithelialized to form a renal vesicle, which then undergoes complex morphogenesis and develops into a mature nephron. Wt1 is expressed in both undifferentiated mesenchymal nephron progenitors and differentiating epithelialized nephron progenitors. It was previously reported that conditional deletion of Wt1 arrests differentiation of nephron progenitors. Expression of Wnt4 and Lhx1, two pivotal genes required for differentiation of nephron progenitors, is downregulated in the Wt1 mutant kidney. Loss-of-function mutations of Wt1 are often found in Wilms’ tumor. It was previously reported that, in Wilms’ tumor, phosphorylation of Erk1/2 (MAP kinases) and IRS (insulin receptor substrate), both of which are downstream of IGF signaling pathway, is increased. Identification of direct target genes regulated by Wt1 is essential in understanding how Wt1 regulates differentiation of nephron progenitors and prevents Wilms’ tumor formation. METHODS We performed Wt1 chromatin immunoprecipitation coupled with next-generation sequencing (ChIP-seq) in embryonic kidneys at E16.5. Sequencing libraries were generated by ligation-mediated PCR following a standard protocol and sequencing was performed on Illumina HiSeq 2000. The sequences were aligned to mouse genome (mm9) by using Bowtie and the data were analyzed by using HOMER and GREAT software. RESULTS We identified over 14,000 genomic target sites of Wt1. Our data show that both Wnt4 and Lhx1 are direct targets of Wt1. In addition, our data show that multiple components of IGF-MAP kinase pathways, such as Irs1, Irs2, Igf1r, Mapk1 (Erk2), and Mapk6 (Erk3), are among the top ranked direct targets of Wt1. De novo motif analysis of our Wt1 ChIP-seq data suggest that Wt1 may interact with Foxc2 and Hox proteins to regulate its target genes. CONCLUSIONS Given that expression of Wnt4 and Lhx1 is downregulated in the Wt1 mutant kidney, our Wt1 ChIP-seq data suggest that Wt1 acts as a transcriptional activator for Wnt4 and Lhx1. Considering that a mouse model of Wilms’ tumor requires both the loss of Wt1 and upregulation of Igf2, our data suggest that Wt1 represses expression of multiple components of IGF-MAP kinase pathways. Loss of Wt1 may cause nephron progenitors to become hypersensitive to IGF signaling. Our results provide new insights into how Wt1 regulates nephrogenesis and prevents Wilms’ tumor formation. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e247-e248 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Eunah Chung More articles by this author Joo-Seop Park More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...