Functional analysis of 5-lipoxygenase promoter repeat variants

Susanna Vikman, Romulo M. Brena, Patrice Armstrong, Jaana Hartiala, Charles B. Stephensen, Hooman Allayee

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21 Scopus citations

Abstract

Variants of a hexanucleotide repeat polymorphism in the promoter of the 5-lipoxygenase (5-LO) gene have been associated with cardiovascular disease traits in humans, which may be due, at least in part, to differential expression of the at-risk alleles. To more fully characterize these variants, we carried out gene expression and DNA methylation studies in primary leukocytes from healthy individuals carrying various 5-LO promoter alleles. Regardless of genotype, 5-LO and 5-LO -activating protein (FLAP) gene expression was higher in granulocytes compared with monocytes and lymphocytes, whereas leukotriene A4 hydrolase (LTA4H) expression was higher in monocytes. In all three leukocyte populations, 5-LO mRNA levels were positively correlated with those of FLAP and LTA4H, with the highest correlation observed in granulocytes. In lymphocytes, individuals homozygous for the shorter 3 and 4 repeat alleles had between 20-35% higher 5-LO, FLAP and LTA4H expression compared with homozygous carriers of the wild-type 5 repeat allele (P = 0.03-0.0001). DNA methylation analysis of four CpG islands in a 1500 bp region encompassing the 5-LO promoter and the first ∼100 bp of intron 1 revealed relatively low overall DNA methylation across all genotypes and leukocyte populations. However, analysis of the promoter repeats themselves demonstrated that, regardless of cell population, the 4 allele was methylated approximately twice as much as the 3 allele (P < 0.0001). Our results demonstrate that, in lymphocytes, the shorter repeat alleles of the 5-LO promoter lead to higher gene expression, which may be regulated through differential DNA methylation of the CpGs located within these repeats.

Original languageEnglish (US)
Pages (from-to)4521-4529
Number of pages9
JournalHuman Molecular Genetics
Volume18
Issue number23
DOIs
StatePublished - 2009

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ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)
  • Molecular Biology

Cite this

Vikman, S., Brena, R. M., Armstrong, P., Hartiala, J., Stephensen, C. B., & Allayee, H. (2009). Functional analysis of 5-lipoxygenase promoter repeat variants. Human Molecular Genetics, 18(23), 4521-4529. https://doi.org/10.1093/hmg/ddp414