Hepatocyte Nuclear Factor–1β Regulates Urinary Concentration and Response to Hypertonicity

Abstract

The transcription factor hepatocyte nuclear factor-1 (HNF-1) is essential for normal kidney development and function. Inactivation of HNF-1 in mouse kidney tubules leads to early-onset cyst formation and postnatal lethality. Here, we used Pkhd1/Cre mice to delete HNF-1 specifically in renal collecting ducts (CDs). CD-specific HNF-1 mutant mice survived long term and developed slowly progressive cystic kidney disease, renal fibrosis, and hydronephrosis. Compared with wild-type littermates, HNF-1 mutant mice exhibited polyuria and polydipsia. Before the development of significant renal structural abnormalities, mutant mice exhibited low urine osmolality at baseline and after water restriction and administration of desmopressin. However, mutant and wild-type mice had similar plasma vasopressin and solute excretion levels. HNF-1 mutant kidneys showed increased expression of aquaporin-2 mRNA but mislocalized expression of aquaporin-2 protein in the cytoplasm of CD cells. Mutant kidneys also had decreased expression of the UT-A urea transporter and collectrin, which is involved in apical membrane vesicle trafficking. Treatment of HNF-1 mutant mIMCD3 cells with hypertonic NaCl inhibited the induction of osmoregulated genes, including , which encodes the transcription factor FXR that is required for maximal urinary concentration. Chromatin immunoprecipitation and sequencing experiments revealed HNF-1 binding to the promoter in wild-type kidneys, and immunoblot analysis revealed downregulated expression of FXR in HNF-1 mutant kidneys. These findings reveal a novel role of HNF-1 in osmoregulation and identify multiple mechanisms, whereby mutations of HNF-1 produce defects in urinary concentration.

Mechanism of Fibrosis in HNF1B-Related Autosomal Dominant Tubulointerstitial Kidney Disease

“…In addition to the formation of kidney cysts, HNF-1b mutant kidneys are characterized by increased interstitial fibrosis. 21 A similar phenotype is seen in humans with heterozygous mutations of UMOD, MUC1, REN, and SEC61A1, which has led to the recent nosology of ADTKD. 1 The resulting clinical manifestations include small kidneys, absence of significant hematuria or proteinuria, slowly progressive decline in GFR, and tubular abnormalities such as hyperuricemia, hypomagnesemia, and reduced urinary concentrating ability.…”

“…Previous studies have shown that collecting duct-specific deletion of HNF-1b using the Pkhd1/Cre deleter strain produces renal fibrosis. 21 To ablate HNF-1b in additional nephron segments, we generated kidney HNF-1b mutant mice using the Ksp/Cre deleter strain, which expresses Cre recombinase in all nephron segments and collecting ducts. 36 Trichrome staining showed that significant interstitial fibrosis was present in kidneys from Ksp/Cre;Hnf1b F/F mice at age 28 days (Supplemental Figure 5A).…”

“…Molecular characterization of HNF-1b mutant mice has shown that HNF-1b plays a significant role in cystic kidney diseases through the regulation of cystogenes such as Pkhd1, Pkd2, Umod, and Kif12. 14,18,19 Recent chromatin immunoprecipitation sequencing (ChIP-seq) experiments have shown that HNF-1b regulates cholesterol metabolism through transcriptional activation of Srebp2 and Pcsk9, 20 urinary concentration through activation of Fxr, 21 and potassium and magnesium homeostasis through activation of Kir5.1. 22 However, the complete gene network governed by HNF-1b in the kidney and the mechanisms whereby human mutations lead to a broad spectrum of clinical phenotypes remain to be fully elucidated.…”

“…14,18 We recently used Pkhd1/Cre 24 mice to ablate Hnf1b specifically in renal collecting ducts. 21 Collecting duct-specific deletion of Hnf1b results in longer survival and slower progression of cystic disease, renal fibrosis, and hydronephrosis. Mutant mice also exhibit polyuria, polydipsia, and impaired urinary concentration recapitulating clinical features of ADTKD in humans with mutations in HNF1B.…”

Involvement of the IP3R-Grp75-VDAC1-MCU calcium axis in proteinuria in adriamycin-induced nephropathy rats

“…following the instructions of the kit, then the cDNA was used for real-time quantitative-PCR analysis using PowerUp SYBR Green Master Mix (Applied Biosystems, USA) and ABI Prism 7500 (Applied 6 Biosystems, USA) according to the protocols provided by the kit [9]. The 2-ΔΔCT method was used to calculate the relative expression of target genes to GAPDH [10]. The primers used were as followed: University, China) were cultured as we previously reported [2].…”