Communicated by Stephen Chanock
The reticulocyte-type 15-lipoxygenase-1 (ALOX15) has antiinflammatory and inflammatory effects, and is implicated in the development of asthma, arthritis, and atherosclerosis. We screened the human ALOX15 gene for variations because genetic variability in ALOX15 may influence these diseases. We detected 11 variations, including five polymorphisms located in the ALOX15 promoter region. One of these polymorphisms, a C-to-T substitution at position c.Γ292, created a novel transcription factor binding site for SPI1. Transcription assays revealed that promoter variants with c.Γ292T transcribe twice as efficiently as all the other promoter variants containing c.Γ292C. This was true in macrophages that constitutively express SPI1, but not in a lung epithelial cell line that does not express SPI1. Mutation of the core-binding site for SPI1 abolished the higher transcriptional activity, and electrophoretic mobility shift assays showed that SPI1 selectively binds to the mutant c.-292T and c.Γ292C promoter. These results were corroborated in primary human macrophages, in which macrophages from heterozygous c.Γ292CT carriers expressed three times more ALOX15 mRNA than macrophages from homozygous c.Γ292CC carriers. We conclude that the c.-292T allele in the ALOX15 promoter generates a novel binding site for the transcription factor SPI1 that results in higher transcription of the gene in macrophages. This may lead to an increase in ALOX15-mediated lipid metabolites, which play a role in inflammation.