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Regulatory mechanisms controlling human hepatocyte nuclear factor 4alpha gene expression.
Mol Cell Biol. 2001 Nov; 21(21):7320-30.MC

Abstract

Hepatocyte nuclear factor 4alpha (HNF-4alpha) (nuclear receptor 2A1) is an essential regulator of hepatocyte differentiation and function. Genetic and molecular evidence suggests that the tissue-restricted expression of HNF-4alpha is regulated mainly at the transcriptional level. As a step toward understanding the molecular mechanism involved in the transcriptional regulation of the human HNF-4alpha gene, we cloned and analyzed a 12.1-kb fragment of its upstream region. Major DNase I-hypersensitive sites were found at the proximal promoter, the first intron, and the more-upstream region comprising kb -6.5, -8.0, and -8.8. By the use of reporter constructs, we found that the proximal-promoter region was sufficient to drive high levels of hepatocyte-specific transcription in transient-transfection assays. DNase I footprint analysis and electrophoretic mobility shift experiments revealed binding sites for HNF-1alpha and -beta, Sp-1, GATA-6, and HNF-6. High levels of HNF-4alpha promoter activity were dependent on the synergism between either HNF-1alpha and HNF-6 or HNF-1beta and GATA-6, which implies that at least two alternative mechanisms may activate HNF-4alpha gene transcription. Chromatin immunoprecipitation experiments with human hepatoma cells showed stable association of HNF-1alpha, HNF-6, Sp-1, and COUP-TFII with the promoter. The last factor acts as a repressor via binding to a newly identified direct repeat 1 (DR-1) sequence of the human promoter, which is absent in the mouse homologue. We present evidence that this sequence is a bona fide retinoic acid response element and that HNF-4alpha expression is upregulated in vivo upon retinoic acid signaling.

Authors+Show Affiliations

Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, 711 10 Herakleion, Crete, Greece.No affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

11585914

Citation

Hatzis, P, and I Talianidis. "Regulatory Mechanisms Controlling Human Hepatocyte Nuclear Factor 4alpha Gene Expression." Molecular and Cellular Biology, vol. 21, no. 21, 2001, pp. 7320-30.
Hatzis P, Talianidis I. Regulatory mechanisms controlling human hepatocyte nuclear factor 4alpha gene expression. Mol Cell Biol. 2001;21(21):7320-30.
Hatzis, P., & Talianidis, I. (2001). Regulatory mechanisms controlling human hepatocyte nuclear factor 4alpha gene expression. Molecular and Cellular Biology, 21(21), 7320-30.
Hatzis P, Talianidis I. Regulatory Mechanisms Controlling Human Hepatocyte Nuclear Factor 4alpha Gene Expression. Mol Cell Biol. 2001;21(21):7320-30. PubMed PMID: 11585914.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Regulatory mechanisms controlling human hepatocyte nuclear factor 4alpha gene expression. AU - Hatzis,P, AU - Talianidis,I, PY - 2001/10/5/pubmed PY - 2002/1/5/medline PY - 2001/10/5/entrez SP - 7320 EP - 30 JF - Molecular and cellular biology JO - Mol Cell Biol VL - 21 IS - 21 N2 - Hepatocyte nuclear factor 4alpha (HNF-4alpha) (nuclear receptor 2A1) is an essential regulator of hepatocyte differentiation and function. Genetic and molecular evidence suggests that the tissue-restricted expression of HNF-4alpha is regulated mainly at the transcriptional level. As a step toward understanding the molecular mechanism involved in the transcriptional regulation of the human HNF-4alpha gene, we cloned and analyzed a 12.1-kb fragment of its upstream region. Major DNase I-hypersensitive sites were found at the proximal promoter, the first intron, and the more-upstream region comprising kb -6.5, -8.0, and -8.8. By the use of reporter constructs, we found that the proximal-promoter region was sufficient to drive high levels of hepatocyte-specific transcription in transient-transfection assays. DNase I footprint analysis and electrophoretic mobility shift experiments revealed binding sites for HNF-1alpha and -beta, Sp-1, GATA-6, and HNF-6. High levels of HNF-4alpha promoter activity were dependent on the synergism between either HNF-1alpha and HNF-6 or HNF-1beta and GATA-6, which implies that at least two alternative mechanisms may activate HNF-4alpha gene transcription. Chromatin immunoprecipitation experiments with human hepatoma cells showed stable association of HNF-1alpha, HNF-6, Sp-1, and COUP-TFII with the promoter. The last factor acts as a repressor via binding to a newly identified direct repeat 1 (DR-1) sequence of the human promoter, which is absent in the mouse homologue. We present evidence that this sequence is a bona fide retinoic acid response element and that HNF-4alpha expression is upregulated in vivo upon retinoic acid signaling. SN - 0270-7306 UR - https://www.unboundmedicine.com/medline/citation/11585914/Regulatory_mechanisms_controlling_human_hepatocyte_nuclear_factor_4alpha_gene_expression_ L2 - https://journals.asm.org/doi/10.1128/MCB.21.21.7320-7330.2001?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -