Hepatocyte nuclear factor-4α plays pivotal roles in the regulation of mouse carboxylesterase 2 gene transcription in mouse liver

https://doi.org/10.1016/j.abb.2006.01.015Get rights and content

Abstract

The mouse carboxylesterase 2 isozyme, mCES2, is thought to play important roles in lipid metabolism and is expressed in the liver, kidney, and small intestine at high levels. In this study, we examined the molecular mechanisms controlling this tissue-specific expression of mCES2, and demonstrated that hepatocyte nuclear factor-4α (HNF-4α) could enhance transcription of the mCES2 gene in vitro and in vivo. It was found that effects of HNF-4α on the level of mCES2 promoter activity were repressed by small heterodimer partner (SHP) and chenodeoxycholic acid (CDCA) in luciferase assays. Accordingly, mCES2 gene transcription was repressed by CDCA treatment in mouse immortalized hepatocytes. Our results suggested that this repression resulted from the combined effects of both inhibition of HNF-4α transactivation ability by SHP and reduction of HNF-4α expression level. These findings show that HNF-4α plays an important role in the regulation of mCES2 gene transcription.

Section snippets

Cell cultures, total RNA isolation, cDNA synthesis, and reverse transcription-polymerase chain reaction (RT-PCR) analysis

HepG2 cells, human hepatoma cells, were obtained from the Institute of Development, Aging and Cancer, Tohoku University (Sendai, Japan). HepG2 cells were maintained at 37 °C with 5% CO2 in Dulbecco’s modified Eagle’s medium (D-MEM) (Invitrogen, Carlsbad, CA) supplemented with 10% (v/v) heat-inactivated fetal bovine serum (FBS) and 50 U/mL penicillin and with 50 μg/mL streptomycin. FLC7 cells [18], human hepatoma cells, were kindly provided by Dr. Seishi Nagamori (Kyorin University, Tokyo, Japan)

Enhancement of promoter activity of the mCES2 gene by expression of HNF-4α

This study was begun by searching for a DR1 element by using a searching program for transcription factor binding sites (Match™, http://www.gene-regulation.com/). As shown in Fig. 1A, the putative DR1 element was found to be close to a transcription start site, and the nucleotide sequence was very similar to those of DR1 elements in the human transthyretin gene and the human apolipoprotein C III gene to which it has been reported that HNF-4α could bind [5]. Next, we performed luciferase assays

Discussion

The results obtained in the first part of this study verified our initial hypothesis that HNF-4α is directly involved in mCES2 gene transcription, and the results obtained in the second part of this study showed that a nuclear receptor cascade triggered by bile acids signal can affect mCES2 mRNA expression. To the best of our knowledge, this is the first report presenting results that show the involvement of nuclear receptors in the transcription of CES genes.

Several HNF-4α isoforms are known,

Acknowledgments

This work was supported in part by a Grant (14572090) from the Ministry of Education, Sciences, Sports, and Culture of Japan. We thank Dr. Seishi Nagamori for providing FLC7 cells.

References (41)

  • T. Furihata et al.

    Arch. Biochem. Biophys.

    (2003)
  • A.J. Watt et al.

    Hepatology

    (2003)
  • H. Hirokane et al.

    J. Biol. Chem.

    (2004)
  • K. Yamagata et al.

    J. Biol. Chem.

    (2004)
  • N. Yanai et al.

    Exp. Cell Res.

    (1994)
  • T. Furihata et al.

    Biochem. Pharmacol.

    (2005)
  • A. del Castillo-Olivares et al.

    J. Biol. Chem.

    (2004)
  • R. Mentlein et al.

    Arch. Biochem. Biophys.

    (1980)
  • M.E. Torres-Padilla et al.

    Mech. Dev.

    (2001)
  • Y. Inoue et al.

    J. Biol. Chem.

    (2004)
  • B. Goodwin et al.

    Mol. Cell

    (2000)
  • T.T. Lu et al.

    Mol. Cell

    (2000)
  • Y. Shimamoto et al.

    J. Biol. Chem.

    (2004)
  • K.D. Setchell et al.

    Gastroenterology

    (1997)
  • S. Reddy et al.

    J. Biol. Chem.

    (1999)
  • M. Nakahara et al.

    J. Biol. Chem.

    (2002)
  • T. Satoh et al.

    Drug Metab. Dispos.

    (2002)
  • T. Satoh et al.

    Annu. Rev. Pharmacol. Toxicol.

    (1998)
  • T. Furihata et al.

    Biochem. J.

    (2004)
  • F.M. Sladek et al.

    Genes Dev.

    (1990)
  • Cited by (37)

    • Emerging role of carboxylesterases in nonalcoholic fatty liver disease

      2022, Biochemical Pharmacology
      Citation Excerpt :

      However, not all reports have observed a link between PPARα activation and CES upregulation. In a separate study of PFOA-treated wild-type (WT) and PPARα-null mice, Ces1c, 1d, 1g, 2a, 2b, and 2e mRNAs and CES2 protein were elevated, which contributed to sustained upregulation of CES activity, whereas Ces1e, 1f mRNA and CES1 protein were dependent on PPARα [86]. The activation of CAR and PXR may explain the selective upregulation of CESs, especially Ces2 subtypes in PPARα-null mice [83].

    • E4bp4 regulates carboxylesterase 2 enzymes through repression of the nuclear receptor Rev-erbα in mice

      2018, Biochemical Pharmacology
      Citation Excerpt :

      Due to important roles of CES in xenobiotic clearance and lipid metabolism, the regulatory mechanisms for its expression are of great interest [23,24]. Several nuclear receptors [including hepatocyte nuclear factor-4 alpha (HNF-4α), pregnane X receptor (PXR), constitutive androstane receptor (CAR), and liver X receptor (LXR)] have been shown to stimulate the expression of certain Ces enzymes (e.g., Ces2a and Ces2c) [6,25–27], whereas proxisome proliferator-activated receptor alpha (PPARα) and small heterodimer partner (SHP) down-regulate Ces enzymes via a direct or indirect mechanism [25,28]. Interestingly, the PAR bZip proteins regulate Ces3 expression via specific binding to the D-box area, probably contributing to circadian expression of the enzyme [29].

    View all citing articles on Scopus
    View full text