Intestinal apolipoprotein A-IV gene transcription is controlled by two hormone-responsive elements: a role for hepatic nuclear factor-4 isoforms

Mol Endocrinol. 2005 Sep;19(9):2320-34. doi: 10.1210/me.2004-0462. Epub 2005 May 31.

Abstract

In the small intestine, the expression of the apolipoprotein (apo) C-III and A-IV genes is restricted to the enterocytes of the villi. We have previously shown that, in transgenic mice, specific expression of the human apo C-III requires a hormone-responsive element (HRE) located in the distal region of the human apoA-IV promoter. This HRE binds the hepatic nuclear factors (HNF)-4alpha and gamma. Here, intraduodenal injections in mice and infections of human enterocytic Caco-2/TC7 cells with an adenovirus expressing a dominant-negative form of HNF-4alpha repress the expression of the apoA-IV gene, demonstrating that HNF-4 controls the apoA-IV gene expression in enterocytes. We show that HNF-4alpha and gamma functionally interact with a second HRE present in the proximal region of the human apoA-IV promoter. New sets of transgenic mice expressing mutated forms of the promoter, combined with the human apo C-III enhancer, demonstrate that, whereas a single HRE is sufficient to reproduce the physiological cephalo-caudal gradient of apoA-IV gene expression, both HREs are required for expression that is restricted to villi. The combination of multiple HREs may specifically recruit regulatory complexes associating HNF-4 and either coactivators in villi or corepressors in crypts.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apolipoproteins A / genetics*
  • Caco-2 Cells
  • Enhancer Elements, Genetic / genetics
  • Enterocytes / metabolism
  • Gene Expression Regulation*
  • Humans
  • Intestine, Small / cytology
  • Intestine, Small / metabolism*
  • Mice
  • Mice, Transgenic
  • Mutation
  • Promoter Regions, Genetic / genetics
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Protein Isoforms / physiology
  • Response Elements / genetics*
  • Transcription, Genetic

Substances

  • Apolipoproteins A
  • Protein Isoforms
  • apolipoprotein A-IV