Alternative 5' untranslated regions are involved in expression regulation of human heme oxygenase-1

PLoS One. 2013 Oct 2;8(10):e77224. doi: 10.1371/journal.pone.0077224. eCollection 2013.

Abstract

The single nucleotide polymorphism rs2071746 and a (GT)n microsatellite within the human gene encoding heme oxygenase-1 (HMOX1) are associated with incidence or outcome in a variety of diseases. Most of these associations involve either release of heme or oxidative stress. Both polymorphisms are localized in the promoter region, but previously reported correlations with heme oxygenase-1 expression remain not coherent. This ambiguity suggests a more complex organization of the 5' gene region which we sought to investigate more fully. We evaluated the 5' end of HMOX1 and found a novel first exon 1a placing the two previously reported polymorphisms in intronic or exonic positions within the 5' untranslated region respectively. Expression of exon 1a can be induced in HepG2 hepatoma cells by hemin and is a repressor of heme oxygenase-1 translation as shown by luciferase reporter assays. Moreover, minigene approaches revealed that the quantitative outcome of alternative splicing within the 5' untranslated region is affected by the (GT)n microsatellite. This data supporting an extended HMOX1 gene model and provide further insights into expression regulation of heme oxygenase-1. Alternative splicing within the HMOX1 5' untranslated region contributes to translational regulation and is a mechanistic feature involved in the interplay between genetic variations, heme oxygenase-1 expression and disease outcome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5' Untranslated Regions*
  • Alternative Splicing
  • Base Sequence
  • Exons
  • Gene Expression Regulation / drug effects*
  • Genes, Reporter
  • Heme Oxygenase-1 / genetics*
  • Heme Oxygenase-1 / metabolism
  • Hemin / pharmacology
  • Hep G2 Cells
  • Humans
  • Introns
  • Luciferases / genetics
  • Luciferases / metabolism
  • Microsatellite Repeats
  • Molecular Sequence Data
  • Polymorphism, Single Nucleotide*
  • Promoter Regions, Genetic*

Substances

  • 5' Untranslated Regions
  • Hemin
  • Luciferases
  • HMOX1 protein, human
  • Heme Oxygenase-1

Grant support

This work was supported by the Federal Ministry of Education and Research (BMBF, Germany, FKZ: 01EO1002 to MB) and by the Deutsche Forschungsgemeinschaft (DFG Hu498/3 to KH and Ba1601/8-1 to MB). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.