Lineage-specific adjacent IFNG and IL26 genes share a common distal enhancer element

Genes Immun. 2012 Sep;13(6):481-8. doi: 10.1038/gene.2012.22. Epub 2012 May 24.

Abstract

Certain groups of physically linked genes remain linked over long periods of evolutionary time. The general view is that such evolutionary conservation confers 'fitness' to the species. Why gene order confers 'fitness' to the species is incompletely understood. For example, linkage of IL26 and IFNG is preserved over evolutionary time yet Th17 lineages express IL26 and Th1 lineages express IFNG. We considered the hypothesis that distal enhancer elements may be shared between adjacent genes, which would require linkage be maintained in evolution. We test this hypothesis using a bacterial artificial chromosome transgenic model with deletions of specific conserved non-coding sequences. We identify one enhancer element uniquely required for IL26 expression but not for IFNG expression. We identify a second enhancer element positioned between IL26 and IFNG required for both IL26 and IFNG expression. One function of this enhancer is to facilitate recruitment of RNA polymerase II to promoters of both genes. Thus, sharing of distal enhancers between adjacent genes may contribute to evolutionary preservation of gene order.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Lineage / genetics
  • Cell Lineage / immunology
  • Chromosomes, Artificial, Bacterial / genetics
  • Conserved Sequence
  • Enhancer Elements, Genetic*
  • Evolution, Molecular*
  • Gene Order
  • Histones / metabolism
  • Humans
  • Interferon-gamma / genetics*
  • Interleukin-22
  • Interleukins / genetics*
  • Mice
  • Mice, Transgenic
  • Models, Genetic
  • Promoter Regions, Genetic
  • RNA Polymerase II / metabolism
  • RNA, Untranslated / genetics
  • RNA, Untranslated / metabolism
  • Sequence Deletion
  • Th1 Cells / immunology
  • Th17 Cells / immunology

Substances

  • Histones
  • IFNG protein, human
  • IL26 protein, human
  • Interleukins
  • RNA, Untranslated
  • Interferon-gamma
  • RNA Polymerase II