RESUMO
Xenopus provides a simple and efficient model system to study nephrogenesis and explore the mechanisms causing renal developmental defects in human. Hnf1b (hepatocyte nuclear factor 1 homeobox b), a gene whose mutations are the most commonly identified genetic cause of developmental kidney disease, is required for the acquisition of a proximo-intermediate nephron segment in Xenopus as well as in mouse. Genetic networks involved in Hnf1b expression during kidney development remain poorly understood. We decided to explore the transcriptional regulation of Hnf1b in the developing Xenopus pronephros and mammalian renal cells. Using phylogenetic footprinting, we identified an evolutionary conserved sequence (CNS1) located several kilobases (kb) upstream the Hnf1b transcription start and harboring epigenomic marks characteristics of a distal enhancer in embryonic and adult renal cells in mammals. By means of functional expression assays in Xenopus and mammalian renal cell lines we showed that CNS1 displays enhancer activity in renal tissue. Using CRISPR/cas9 editing in Xenopus tropicalis, we demonstrated the in vivo functional relevance of CNS1 in driving hnf1b expression in the pronephros. We further showed the importance of Pax8-CNS1 interaction for CNS1 enhancer activity allowing us to conclude that Hnf1b is a direct target of Pax8. Our work identified for the first time a Hnf1b renal specific enhancer and may open important perspectives into the diagnosis for congenital kidney anomalies in human, as well as modeling HNF1B-related diseases.
Assuntos
Nefropatias , Rim , Humanos , Adulto , Camundongos , Animais , Fator 1-beta Nuclear de Hepatócito/genética , Filogenia , Rim/anormalidades , Nefropatias/genética , Sequências Reguladoras de Ácido Nucleico , Xenopus/genética , Xenopus laevis/genética , Mamíferos/genética , Fator de Transcrição PAX8/genéticaRESUMO
Suppressor of fused (Sufu) is a negative regulator of the Hedgehog pathway both in Drosophila and vertebrates. Here, we report the genomic organization of the mouse Sufu gene (mSufu). This gene comprises 11 exons spanning more than 30 kb and encodes a protein with a putative PEST sequence. DNA-consensus sequences recognized by basic helix-loop-helix (bHLH) proteins, referred to as E-box motifs, are found in the 5' flanking region. Analysis by single-strand conformation polymorphism and radiation hybrid positioned the Sufu locus to the distal end of mouse Chr 19 between D19Mit102 and D19Mit9, near the Fgf8 and dactylin genes. Mouse Sufu is expressed in various tissues, particularly in the nervous system, ectoderm, and limbs, throughout the developing embryo. Sufu binds with all three Gli proteins, with different affinities. This report, in conjunction with recent studies, points out the importance of Sufu in mouse embryonic development.
Assuntos
Genes/genética , Proteínas Repressoras/genética , Processamento Alternativo , Animais , Sequência de Bases , Mapeamento Cromossômico , DNA/química , DNA/genética , Embrião de Mamíferos/metabolismo , Éxons , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Hibridização In Situ , Íntrons , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Muridae , Proteínas Oncogênicas/genética , Proteínas Oncogênicas/metabolismo , Ligação Proteica , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Repressoras/metabolismo , Análise de Sequência de DNA , Transativadores , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Técnicas do Sistema de Duplo-Híbrido , Proteína GLI1 em Dedos de ZincoRESUMO
The Suppressor of fused [Su(fu)] gene of Drosophila melanogaster encodes a protein containing a PEST sequence [sequence enriched in proline (P), glutamic acid (E), serine (S) and threonine (T)] which acts as an antagonist to the serine-threonine kinase Fused in Hedgehog (Hh) signal transduction during embryogenesis. The Su(fu) gene isolated from a distantly related Drosophila species, D. virilis, shows significantly high homology throughout its protein sequence with its D. melanogaster counterpart. We show that these two Drosophila homologs of Su(fu) are functionally interchangeable in enhancing the fused phenotype. We have also isolated mammalian homologs of Su(fu). The absence of the PEST sequence in the mammalian Su(fu) protein suggests a different regulation for this product between fly and vertebrates. Using the yeast two-hybrid method, we show that the murine Su(fu) protein can interact directly with the Fused and Cubitus interruptus proteins, known partners of Su(fu) in Drosophila. These data are discussed in the light of their evolutionary relationships.
