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The mouse alpha-albumin (afamin) promoter is differentially regulated by hepatocyte nuclear factor 1α and hepatocyte

Hua Liu1, Hui Ren, Brett T Spear

  • 1Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, Kentucky 40536, USA.

DNA and Cell Biology
|October 29, 2010
PubMed

Insights

Hepatocyte nuclear factor 1 (HNF1) binding sites in the alpha-albumin (AFM) promoter are conserved across mammals. HNF1α activates AFM transcription, while HNF1β can inhibit this activation, influencing gene timing.

Area of Science:

  • Genetics
  • Molecular Biology
  • Biochemistry

Background:

  • Alpha-albumin (AFM) is a liver-expressed gene within the albumin gene family.
  • Its activation at birth suggests developmental regulation.
  • Hepatocyte nuclear factor 1 (HNF1) is a key transcription factor involved in liver gene expression.

Purpose of the Study:

  • To identify and characterize HNF1-binding sites in the AFM promoter.
  • To investigate the roles of HNF1α and HNF1β in regulating AFM gene expression.
  • To understand the evolutionary conservation of HNF1-binding sites in the albumin gene family.

Main Methods:

  • Identification of conserved HNF1-binding sites in the AFM promoter using bioinformatic analysis.
  • HNF1 binding assays to confirm protein-DNA interactions.
  • Mutational analysis in transfected cells to assess the functional importance of binding sites.
  • Comparison of HNF1-binding sites across albumin family gene promoters.

Main Results:

  • Two highly conserved HNF1-binding sites were identified in the AFM promoter.
  • Both HNF1α and HNF1β bind to these sites, with the distal site being more critical.
  • HNF1α is a more potent activator of AFM transcription than HNF1β.
  • HNF1β can dominantly inhibit HNF1α-mediated AFM transactivation when co-expressed.

Conclusions:

  • HNF1 transcription factors play a crucial role in regulating AFM gene expression.
  • The differential activity and interaction of HNF1α and HNF1β contribute to the precise temporal activation of albumin family genes.
  • Evolutionary analysis reveals the presence and loss of HNF1-binding sites within the albumin gene family, reflecting gene duplication and divergence.

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