Influence of a Coronary Artery Disease-Associated Genetic Variant on FURIN Expression and Effect of Furin on Macrophage Behavior.

Objective- Genome-wide association studies have revealed a robust association between genetic variation on chromosome 15q26.1 and coronary artery disease (CAD) susceptibility; however, the underlying biological mechanism is still unknown. The lead CAD-associated genetic variant (rs17514846) at this locus resides in the FURIN gene. In advanced atherosclerotic plaques, furin is expressed primarily in macrophages. We investigated whether this CAD-associated variant alters FURIN expression and whether furin affects monocyte/macrophage behavior. Approach and Results- A quantitative reverse transcription polymerase chain reaction analysis showed that leukocytes from individuals carrying the CAD risk allele (A) of rs17514846 had increased FURIN expression. A chromatin immunoprecipitation assay revealed higher RNA polymerase II occupancy in the FURIN gene in mononuclear cells of individuals carrying this allele. A reporter gene assay in transiently transfected monocytes/macrophages indicated that the CAD risk allele had higher transcriptional activity than the nonrisk allele (C). An analysis of isogenic monocyte cell lines created by CRISPR (clustered regularly interspaced short palindromic repeats)-mediated genome editing showed that isogenic cells with the A/A genotype for rs17514846 had higher FURIN expression levels than the isogenic cells with the C/C genotype. An electrophoretic mobility shift assay exhibited preferential binding of a nuclear protein to the risk allele. Studies of monocytes/macrophages with lentivirus-mediated furin overexpression or shRNA (short hairpin RNA)-induced furin knockdown showed that furin overexpression promoted monocyte/macrophage migration, increased proliferation, and reduced apoptosis whereas furin knockdown had the opposite effects. Conclusions- Our study shows that the CAD-associated genetic variant increases FURIN expression and that furin promotes monocyte/macrophage migration and proliferation while inhibiting apoptosis, providing a biological mechanism for the association between variation at the chromosome 15q26.1 locus and CAD risk.