Genotypic Effect of the -565C>T Polymorphism in the ABCA1 Gene Promoter on ABCA1 Expression and Severity of Atherosclerosis.
Kyriakou, Theodosios; Hodgkinson, Conrad; Pontefract, David E.; Iyengar, Srikanth; Howell, W Martin; Wong, Yuk-ki; Eriksson, Per; Ye, Shu
Arteriosclerosis, Thrombosis & Vascular Biology.
25(2):418-423, February 2005.
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Objective-: Loss-of-function mutations of the ATP-binding cassette transporter A1 (ABCA1) gene cause Tangier disease, a rare genetic disorder with accumulation of lipid-laden macrophages and increased risk of atherosclerosis. Common variants of this gene may be a genetic factor for atherosclerosis in the general population. This study was performed to test the reported association between the -565C>T polymorphism and atherosclerosis severity and to investigate whether this variant per se had an effect on promoter activity of the ABCA1 gene.
Methods and Results-: A cohort of patients with coronary atherosclerosis were genotyped for the -565C>T polymorphism. Logistic regression analyses showed that homozygotes of the -565T allele had greatest mean number of diseased coronary arteries, particular in nonsmokers. Real-time reverse-transcriptase polymerase chain reaction showed that in atherosclerotic plaques removed from patients undergoing endarteretomy, ABCA1 expression levels were lowest in those who had the T/T genotype and highest in those of the C/C genotype. Transfection and reporter assays demonstrated that in cultured macrophages, the -565T allelic promoter had a lower activity in driving gene expression than the -565C allelic promoter. Electrophoretic mobility shift assays displayed differential binding of nuclear proteins to the 2 alleles.
Conclusions-: These results indicate that the -565C>T polymorphism has an allele-specific effect on ABCA1 gene expression and provide further evidence of a genotypic effect on coronary atherosclerosis severity.
(C) 2005 American Heart Association, Inc.