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Updated: Jul 20, 2026

In Vitro Cultivation Techniques for Modeling Liver Organogenesis, Building Assembloids, and Designing Synthetic Tissues using Human Cell Lines
Published on: April 18, 2025
Mitogen-activated protein kinase-mediated disruption of enhancer-promoter communication inhibits hepatocyte nuclear
Pantelis Hatzis1, Irene Kyrmizi, Iannis Talianidis
1Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, Herakleion, Crete, Greece.
Abstract:
Hepatocyte nuclear factor 4 (HNF-4) is a key member of the transcription factor network regulating hepatocyte differentiation and function. Activation of the HNF-4 gene involves physical interaction between a distant enhancer and the proximal promoter region, bound by distinct sets of transcription factors. Here we report that, upon mitogen-activated protein (MAP) kinase activation, HNF-4 expression is downregulated in human hepatoma cells. This effect is mediated by the loss of CEBPalpha expression. During MAP kinase signaling, the recruitment of HNF-3beta and HNF-1alpha to the HNF-4 enhancer and RNA polymerase II to the proximal HNF-4 promoter was compromised. CBP, Brg1, and TFIIB were also dissociated from the HNF-4 regulatory regions, and the enhancer-promoter complex was disrupted. Interestingly, the extent of nucleosome acetylation did not decrease at either regulatory region, and HNF-6 and HNF-1alpha, as well as components of the TFIID, remained associated with the proximal promoter during the repressed state. The results point to an absolute requirement of enhancer-promoter communication for maintaining the active state of the HNF-4 gene and provide evidence for a molecular bookmarking mechanism, which may contribute to the prevention of permanent silencing of the locus during the repressed state.
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