title: PAX8-mediated activation of the wt1 tumor suppressor gene.
abstract: The developing renal system has long been exploited to study the regulation of gene expression during mesenchymal-epithelial transitions. Several transcription factors, including WT1 and PAX8, are expressed early in nephrogenesis and play a key role in this process. The expression of PAX8 occurs in the induced mesenchyme of the developing kidney prior to the upregulation of WT1 levels in the same cells. In this report, we assessed whether the Pax-8 gene product resides upstream of wt1 in a common regulatory pathway. Transfection studies, as well as gel-shift assays, indicate that PAX8 transactivates wt1 through elements within a 38 bp conserved motif, present in human and murine promoters. Two PAX8 isoforms, generated by alternative splicing at the C-terminus and previously thought to lack transactivation potential, were found to be capable of activating wt1 expression. We also demonstrate that the endogenous wt1 promoter can be upregulated by exogenously supplied PAX8, suggesting that a function of PAX8 during mesenchymal--epithelial cell transition in renal development is to induce wt1 gene expression.
authors.affiliation: Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Dehbi
authors.forename: J
authors.initials: J
authors.lastname: Pelletier
mesh_terms: D016475:3T3 Cells; D000818:Animals; D019556:COS Cells; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D004847:Epithelial Cells; D018507:Gene Expression Regulation, Developmental; D016162:Genes, Wilms Tumor; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000473:pathology; D008648:Mesoderm / Q000166:cytology; D051379:Mice; D009687:Nuclear Proteins; D000072636:PAX8 Transcription Factor; D051761:Paired Box Transcription Factors; D012326:RNA Splicing; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D013045:Species Specificity; D015534:Trans-Activators / Q000502:physiology*; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D014162:Transfection; D014407:Tumor Cells, Cultured; D025721:WT1 Proteins
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D000072636:PAX8 Transcription Factor; C083325:PAX8 protein, human; D051761:Paired Box Transcription Factors; C499496:Pax8 protein, mouse; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D025721:WT1 Proteins