CREB-binding Protein Is a Transcriptional Coactivator for Hepatocyte Nuclear Factor-4 and Enhances Apolipoprotein Gene Expression

HNF-4 (hepatocyte nuclear factor 4) is a key regulator of liver-specific gene expression in mammals. We have shown previously that the activity of the human APOC3 (apolipoprotein C-III) promoter is positively regulated by the anti-inflammatory cytokine TGFβ (transforming growth factor β) and its effectors Smad3 (similar to mothers against decapentaplegic 3) and Smad4 proteins via physical and functional interactions between Smads and HNF-4. We now show that the pro-inflammatory cytokine TNFα (tumour necrosis factor α) antagonizes TGFβ for the regulation of APOC3 gene expression in hepatocytes. TNFα was a strong inhibitor of the activity of apolipoprotein promoters that harbour HNF-4 binding sites and this inhibition required HNF-4. Using specific inhibitors of TNFα-induced signalling pathways, it was shown that inhibition of the APOC3 promoter by TNFα involved NF-κB (nuclear factor κB). Latent membrane protein 1 of the Epstein–Barr virus, which is an established potent activator of NF-κB as well as wild-type forms of various NF-κB signalling mediators, also inhibited strongly the APOC3 promoter and the transactivation function of HNF-4. TNFα had no effect on the stability or the nuclear localization of HNF-4 in HepG2 cells, but inhibited the binding of HNF-4 to the proximal APOC3 HRE (hormone response element). Using the yeast-transactivator-GAL4 system, we showed that both AF-1 and AF-2 (activation functions 1 and 2) of HNF-4 are inhibited by TNFα and that this inhibition was abolished by overexpression of different HNF-4 co-activators, including PGC-1 (peroxisome-proliferator-activated-receptor-γ co-activator 1), CBP [CREB (cAMP-response-element-binding protein) binding protein] and SRC3 (steroid receptor co-activator 3). In summary, our findings indicate that TNFα, or other factors that trigger an NF-κB response in hepatic cells, inhibit the transcriptional activity of the APOC3 and other HNF-4-dependent promoters and that this inhibition could be accounted for by a decrease in DNA binding and the down-regulation of the transactivation potential of the AF-1 and AF-2 domains of HNF-4.

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Sterol Regulatory Element-binding Protein-2 Interacts with Hepatocyte Nuclear Factor-4 to Enhance Sterol Isomerase Gene Expression in Hepatocytes

Journal of Biological Chemistry ◽

10.1074/jbc.m302387200 ◽

2003 ◽

Vol 278 (38) ◽

pp. 36176-36182 ◽

Cited By ~ 51

Author(s):

Koichi Misawa ◽

Taro Horiba ◽

Naoto Arimura ◽

Yuko Hirano ◽

Jun Inoue ◽

...

Keyword(s):

Gene Expression ◽

Binding Protein ◽

Regulatory Element ◽

Nuclear Factor ◽

Hepatocyte Nuclear Factor ◽

Element Binding Protein ◽

Sterol Regulatory Element ◽

Hepatocyte Nuclear Factor 4

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Antagonism between apolipoprotein AI regulatory protein 1, Ear3/COUP-TF, and hepatocyte nuclear factor 4 modulates apolipoprotein CIII gene expression in liver and intestinal cells

Molecular and Cellular Biology ◽

10.1128/mcb.12.4.1708-1718.1992 ◽

1992 ◽

Vol 12 (4) ◽

pp. 1708-1718

Author(s):

M Mietus-Snyder ◽

F M Sladek ◽

G S Ginsburg ◽

C F Kuo ◽

J A Ladias ◽

...

Keyword(s):

Gene Expression ◽

Regulatory Protein ◽

Lipid Binding ◽

Hepatic Tissue ◽

Nuclear Factor ◽

Apolipoprotein Ai ◽

Hepatocyte Nuclear Factor ◽

Apolipoprotein Ciii ◽

Caco2 Cells ◽

Hepatocyte Nuclear Factor 4

Apolipoprotein CIII (apoCIII), a lipid-binding protein involved in the transport of triglycerides and cholesterol in the plasma, is synthesized primarily in the liver and the intestine. A cis-acting regulatory element, C3P, located at -90 to -66 upstream from the apoCIII gene transcriptional start site (+1), is necessary for maximal expression of the apoCIII gene in human hepatoma (HepG2) and intestinal carcinoma (Caco2) cells. This report shows that three members of the steroid receptor superfamily of transcription factors, hepatocyte nuclear factor 4 (HNF-4), apolipoprotein AI regulatory protein 1 (ARP-1), and Ear3/COUP-TF, act at the C3P site. HNF-4 activates apoCIII gene expression in HepG2 and Caco2 cells, while ARP-1 and Ear3/COUP-TF repress its expression in the same cells. HNF-4 activation is abolished by increasing amounts of ARP-1 or Ear3/COUP-TF, and repression by ARP-1 or Ear3/COUP-TF is alleviated by increasing amounts of HNF-4. HNF-4 and ARP-1 bind with similar affinities to the C3P site, suggesting that their opposing transcriptional effects may be mediated by direct competition for DNA binding. HNF-4 and ARP-1 mRNAs are present within the same cells in the liver and intestine, and protein extracts from hepatic tissue, HepG2, and Caco2 cells contain significantly more HNF-4 than ARP-1 or Ear3/COUP-TF binding activities. These findings suggest that the transcription of the apoCIII gene in vivo is dependent, at least in part, upon the intracellular balance of these positive and negative regulatory factors.

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Bile Acid Reduces the Secretion of Very Low Density Lipoprotein by Repressing Microsomal Triglyceride Transfer Protein Gene Expression Mediated by Hepatocyte Nuclear Factor-4

Journal of Biological Chemistry ◽

10.1074/jbc.m404255200 ◽

2004 ◽

Vol 279 (44) ◽

pp. 45685-45692 ◽

Cited By ~ 110

Author(s):

Hisako Hirokane ◽

Mayuko Nakahara ◽

Shizuko Tachibana ◽

Makoto Shimizu ◽

Ryuichiro Sato

Keyword(s):

Gene Expression ◽

Chenodeoxycholic Acid ◽

Microsomal Triglyceride Transfer Protein ◽

Nuclear Factor ◽

Hepatocyte Nuclear Factor ◽

Hep G2 ◽

Hep G2 Cells ◽

Apo B ◽

Transfer Protein ◽

Hepatocyte Nuclear Factor 4

Microsomal triglyceride transfer protein (MTP) is involved in the transfer of triglycerides, cholesterol esters, and phospholipids to newly synthesized apolipoprotein (apo) B. It is therefore essential for lipoprotein synthesis and secretion in the liver and the small intestine. Although several recent experiments have revealed the transcriptional regulation of the MTP gene, little has been revealed to date about hepatocyte nuclear factor-4 (HNF-4)-dependent regulation. We here report that the human MTP gene promoter contains a pair of functional responsive elements for HNF-4 and HNF-1, the latter of which is another target gene of HNF-4. Chromatin immunoprecipitation assays provide evidence that endogenous HNF-4 and HNF-1 can bind these elements in chromatin. In Hep G2 cells overexpression of either a dominant negative form of HNF-4 or small interfering RNAs (siRNAs) against HNF-4 dramatically reduces the activities of both the wild type and the HNF-4 site mutant MTP promoter. This suggests that HNF-4 regulates MTP gene expression either directly or indirectly through elevated HNF-1 levels. When Hep G2 cells were cultured with chenodeoxycholic acid (CDCA), a ligand for the farnesoid X receptor (FXR), mRNA levels for MTP and apo B were reduced because of increased expression of the factor small heterodimer partner (SHP), which factor suppresses HNF-4 activities. Chenodeoxycholic acid, but not a synthetic FXR ligand, attenuated expression of HNF-4, bringing about a further suppression of MTP gene expression. Over time the intracellular MTP protein levels and apo B secretion in the culture medium significantly declined. These results indicate that two nuclear receptors, HNF-4 and FXR, are closely involved in MTP gene expression, and the results provide evidence for a novel interaction between bile acids and lipoprotein metabolism.

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Contribution of Hepatocyte Nuclear Factor-4 to Down-Regulation ofCYP2D6 Gene Expression by Nitric Oxide

Molecular Pharmacology ◽

10.1124/mol.61.1.194 ◽

2002 ◽

Vol 61 (1) ◽

pp. 194-200 ◽

Cited By ~ 36

Author(s):

Hirokazu Hara ◽

Tetsuo Adachi

Keyword(s):

Gene Expression ◽

Nitric Oxide ◽

Nuclear Factor ◽

Hepatocyte Nuclear Factor ◽

Down Regulation ◽

Hepatocyte Nuclear Factor 4

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Antagonism between apolipoprotein AI regulatory protein 1, Ear3/COUP-TF, and hepatocyte nuclear factor 4 modulates apolipoprotein CIII gene expression in liver and intestinal cells.

Molecular and Cellular Biology ◽

10.1128/mcb.12.4.1708 ◽

1992 ◽

Vol 12 (4) ◽

pp. 1708-1718 ◽

Cited By ~ 180

Author(s):

M Mietus-Snyder ◽

F M Sladek ◽

G S Ginsburg ◽

C F Kuo ◽

J A Ladias ◽

...

Keyword(s):

Gene Expression ◽

Regulatory Protein ◽

Lipid Binding ◽

Hepatic Tissue ◽

Nuclear Factor ◽

Apolipoprotein Ai ◽

Hepatocyte Nuclear Factor ◽

Apolipoprotein Ciii ◽

Caco2 Cells ◽

Hepatocyte Nuclear Factor 4

Apolipoprotein CIII (apoCIII), a lipid-binding protein involved in the transport of triglycerides and cholesterol in the plasma, is synthesized primarily in the liver and the intestine. A cis-acting regulatory element, C3P, located at -90 to -66 upstream from the apoCIII gene transcriptional start site (+1), is necessary for maximal expression of the apoCIII gene in human hepatoma (HepG2) and intestinal carcinoma (Caco2) cells. This report shows that three members of the steroid receptor superfamily of transcription factors, hepatocyte nuclear factor 4 (HNF-4), apolipoprotein AI regulatory protein 1 (ARP-1), and Ear3/COUP-TF, act at the C3P site. HNF-4 activates apoCIII gene expression in HepG2 and Caco2 cells, while ARP-1 and Ear3/COUP-TF repress its expression in the same cells. HNF-4 activation is abolished by increasing amounts of ARP-1 or Ear3/COUP-TF, and repression by ARP-1 or Ear3/COUP-TF is alleviated by increasing amounts of HNF-4. HNF-4 and ARP-1 bind with similar affinities to the C3P site, suggesting that their opposing transcriptional effects may be mediated by direct competition for DNA binding. HNF-4 and ARP-1 mRNAs are present within the same cells in the liver and intestine, and protein extracts from hepatic tissue, HepG2, and Caco2 cells contain significantly more HNF-4 than ARP-1 or Ear3/COUP-TF binding activities. These findings suggest that the transcription of the apoCIII gene in vivo is dependent, at least in part, upon the intracellular balance of these positive and negative regulatory factors.

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Hepatocyte Nuclear Factor 4 alpha (HNF4α) Activation is Essential for Termination of Liver Regeneration

10.1101/304808 ◽

2018 ◽

Author(s):

Ian Huck ◽

Sumedha Gunewardena ◽

Regina Espanol-Suner ◽

Holger Willenbring ◽

Udayan Apte

Keyword(s):

Gene Expression ◽

Liver Regeneration ◽

Target Gene ◽

Nuclear Factor ◽

Hepatocyte Nuclear Factor ◽

Hepatic Differentiation ◽

Target Gene Expression ◽

Protein Levels ◽

Hepatocyte Nuclear Factor 4

AbstractHepatocyte Nuclear Factor 4 alpha (HNF4α) is critical for hepatic differentiation. Recent studies have highlighted its role in inhibition of hepatocyte proliferation and tumor suppression. However, the role of HNF4α in liver regeneration is not known. We hypothesized that hepatocytes modulate HNF4α activity when navigating between differentiated and proliferative states during liver regeneration. Western blot analysis revealed a rapid decline in nuclear and cytoplasmic HNF4α protein levels accompanied with decreased target gene expression within 1 hour after 2/3 partial hepatectomy (post-PH) in C57BL/6J mice. HNF4α protein expression did not recover to the pre-PH levels until day 3. Hepatocyte-specific deletion of HNF4α (HNF4α-KO) in mice resulted in 100% mortality post-PH despite increased proliferative marker expression throughout regeneration. Sustained loss of HNF4α target gene expression throughout regeneration indicated HNF4α-KO mice were unable to compensate for loss of HNF4α transcriptional activity. Deletion of HNF4α resulted in sustained proliferation accompanied by c-myc and cyclin D1 over expression and a complete deficiency of hepatocyte function after PH. Interestingly, overexpression of degradation-resistant HNF4α in hepatocytes did not prevent initiation of regeneration after PH. Finally, AAV8-mediated reexpression of HNF4α in hepatocytes of HNF4α-KO mice post-PH restored HNF4α protein levels, induced target gene expression and improved survival of HNF4α-KO mice post-PH. In conclusion, these data indicate that HNF4α reexpression following initial decrease is critical for hepatocytes to exit from cell cycle and resume function during the termination phase of liver regeneration. These results reveal the role of HNF4α in liver regeneration and have implications for therapy of liver failure.

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Human Hepatocyte Nuclear Factor 4-α encodes isoforms with distinct transcriptional functions

10.1101/585604 ◽

2019 ◽

Author(s):

Élie Lambert ◽

Jean-Philippe Babeu ◽

Joël Simoneau ◽

Dominique Lévesque ◽

Émilie Jolibois ◽

...

Keyword(s):

Gene Expression ◽

Regulatory Mechanisms ◽

Nuclear Factor ◽

Omics Data ◽

Hepatocyte Nuclear Factor ◽

Transcriptional Regulatory ◽

Hepatocyte Nuclear Factor 4 ◽

Transcriptional Regulatory Mechanisms ◽

First Time ◽

Reduced Activity

SUMMARYHNF4α is a nuclear receptor produced as 12 isoforms from two promoters by alternative splicing. In order to characterize the transcriptional capacities of all 12 HNF4α isoforms, stable lines expressing each isoform were generated. The entire transcriptome associated with each isoform was analyzed as well as their respective interacting proteome. Major differences were noted in the transcriptional function of these isoforms. The α1 and α2 isoforms were the most potent regulators of gene expression while the α3 isoform exhibited significantly reduced activity. The α4, α5 and α6 isoforms, which use an alternative first exon, were characterized for the first time, and showed a greatly reduced transcriptional potential with an inability to recognize the consensus response element of HNF4α. Several transcription factors and coregulators were identified as potential specific partners for certain HNF4α isoforms. An analysis integrating the vast amount of omics data enabled the identification of transcriptional regulatory mechanisms specific to certain HNF4α isoforms, hence demonstrating the importance of considering all isoforms given their seemingly diverse functions.

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