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Atherosclerosis is an inflammatory disease characterized by lipid accumulation in the artery wall. The 15-lipoxygenase (15-LOX) is an enzyme with pro-inflammatory and anti-inflammatory effects and is implicated in the development of atherosclerosis. We screened the human 15-LOX gene for variations because genetic variability in 15-LOX might influence atherosclerosis. We detected five mutations in the 15-LOX promoter region, which combined to ten different haplotypes. One of these polymorphisms, C3175T, created a novel transcription factor binding site for PU.1. In vitro assays revealed that promoters with T3175 transcribe twice as efficient as all the other promoters containing C3175. However this was only true in macrophage cell lines that constitutively express PU.1 but not in lung epithelial cell lines which do not express PU.1. Mutation of the core binding site for PU.1 abolished the higher transcriptional activity and BandShift assays showed that PU.1 selectively binds to the mutant T3175 promoter in macrophages. The transcription and BandShift results were corroborated in primary human macrophages, where macrophages with the T3175 promoter transcribed more endogenous 15-LOX mRNA than macrophages with the wildtype promoter. Intriguingly, the same polymorphism showed a tendency to be protective against atherosclerosis in a case-control study for coronary artery disease involving 343 men. We conclude that the C3175T polymorphism in the 15-LOX promoter generates a novel binding site for the transcription factor PU.1 which results in higher transcription of the gene. This may lead to an increased 15-LOX dependent lipoxin production which may be atheroprotective.
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J. Vasc. Biol. 42, Sup:2 (2005) p57