Hepatocyte nuclear factor-1β regulates Wnt signaling through genome-wide competition with β-catenin/lymphoid enhancer binding factor

Hepatocyte nuclear factor-1β (HNF-1β) is a tissue-specific transcription factor that is essential for normal kidney development and renal tubular function. Mutations of HNF-1β produce cystic kidney disease, a phenotype associated with deregulation of canonical (β-catenin-dependent) Wnt signaling. Here, we show that ablation of HNF-1β in mIMCD3 renal epithelial cells produces hyperresponsiveness to Wnt ligands and increases expression of Wnt target genes, including Axin2, Ccdc80, and Rnf43. Levels of β-catenin and expression of Wnt target genes are also increased in HNF-1β mutant mouse kidneys. Genome-wide ChIP-seq in wild-type and mutant cells showed that ablation of HNF-1β increases by five-fold the number of sites on chromatin that are occupied by β-catenin. Remarkably, 50% of the sites that are occupied by β-catenin in HNF-1β mutant cells colocalize with HNF-1β binding sites in wild-type cells, indicating widespread reciprocal binding. We found that the Wnt target genes Ccdc80 and Rnf43 contain a novel composite DNA element comprising a β-catenin/lymphoid enhancer binding factor (LEF) site overlapping with an HNF-1β half-site. HNF-1β directly competes with the binding of β-catenin/LEF complexes to this element and thereby inhibits β-catenin-dependent transcription. Collectively, these studies reveal a novel mechanism whereby a transcription factor constrains canonical Wnt signaling through direct inhibition of β-catenin/LEF chromatin binding. RNA-seq and β-catenin ChIP-seq of HNF-1β-deficient and WT mIMCD3 cell lines treated with Mock and Wnt3a.