Role of the Hepatocyte Nuclear Factor-1β (HNF-1β) C-terminal Domain in Pkhd1 (ARPKD) Gene Transcription and Renal Cystogenesis

Thomas Hiesberger,Xinli Shao,Eric Gourley,Andreas Reimann,Marco Pontoglio,Peter Igarashi

doi:10.1074/jbc.m414121200

Abstract

Hepatocyte nuclear factor-1beta (HNF-1beta) is a homeodomain-containing transcription factor that regulates tissue-specific gene expression in the kidney and other epithelial organs. Mutations of HNF-1beta produce congenital cystic abnormalities of the kidney, and previous studies showed that HNF-1beta regulates the expression of the autosomal recessive polycystic kidney disease (ARPKD) gene, Pkhd1. Here we show that the C-terminal region of HNF-1beta contains an activation domain that is functional when fused to a heterologous DNA-binding domain. An HNF-1beta deletion mutant lacking the C-terminal domain interacts with wild-type HNF-1beta, binds DNA, and functions as a dominant-negative inhibitor of a chromosomally integrated Pkhd1 promoter. The activation of the Pkhd1 promoter by wild-type HNF-1beta is stimulated by sodium butyrate or coactivators CREB (cAMP-response element)-binding protein (CBP) and P/CAF. The interaction with CBP and P/CAF requires the C-terminal domain. Expression of an HNF-1beta C-terminal deletion mutant in transgenic mice produces renal cysts, increased cell proliferation, and dilatation of the ureter similar to mice with kidney-specific inactivation of HNF-1beta. Pkhd1 expression is inhibited in cystic collecting ducts but not in non-cystic proximal tubules, despite transgene expression in this nephron segment. We conclude that the C-terminal domain of HNF-1beta is required for the activation of the Pkhd1 promoter. Deletion mutants lacking the C-terminal domain function as dominant-negative mutants, possibly by preventing the recruitment of histone acetylases to the promoter. Cyst formation correlates with inhibition of Pkhd1 expression, which argues that mutations of HNF-1beta produce kidney cysts by down-regulating the ARPKD gene, Pkhd1. Expression of HNF-1alpha in proximal tubules may protect against cystogenesis.

Highlights

Hepatocyte nuclear factor-1␤ (HNF-1␤) is a homeodomain-containing transcription factor that regulates tissue-specific gene expression in the kidney and other epithelial organs
hepatocyte nuclear factor-1 (HNF-1)␤⌬C Mutant Is Capable of Dimerization and DNA Binding—To determine whether the C-terminal domain of HNF-1␤ is required for transcriptional activation of the Pkhd1 promoter, we produced a C-terminal truncated mouse mutant (HNF-1␤⌬C)
Lysates programmed with full-length FLAG-tagged HNF-1␤ produced a DNA-protein complex that was not seen in lysates programmed with empty expression plasmid (Fig. 1B, lanes 1 and 2)

Summary

Introduction

Hepatocyte nuclear factor-1␤ (HNF-1␤) is a homeodomain-containing transcription factor that regulates tissue-specific gene expression in the kidney and other epithelial organs. Mutations of HNF-1␤ produce congenital cystic abnormalities of the kidney, and previous studies showed that HNF-1␤ regulates the expression of the autosomal recessive polycystic kidney disease (ARPKD) gene, Pkhd. An HNF-1␤ deletion mutant lacking the C-terminal domain interacts with wild-type HNF-1␤, binds DNA, and functions as a dominant-negative inhibitor of a chromosomally integrated Pkhd promoter. HNF-1␣ knock-out mice exhibit glycosuria, amino aciduria, and phosphaturia and show decreased expression of genes encoding glucose and phosphate transporters in the proximal tubule In addition to renal cysts, other kidney abnormalities caused by mutations of HNF-1␤ include oligomeganephronia, familial juvenile hyperuricemic nephropathy, and renal agenesis or hypoplasia [21]

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