Genetic variation in the circadian rhythm genes, clock and clif, and possible association with coronary artery disease in individuals of Chinese Han descent

Abstract

Clock is a core, well-established, circadian gene, and clif is a newly discovered circadian gene, both of which not only maintain the circadian rhythm of cells but also regulate some organic functions. The purpose of this study was to determine whether genetic variations (single nucleotide polymorphisms – SNPs) in clock and/or clif genes associate with coronary artery disease (CAD). We silenced the clock and clif genes in cells and mice. The mRNA levels of clock, clif, pai-1, and tm of mice were examined using Reverse transcription polymerase chain reaction (RT-PCR). Plasminogen activator inhibitor 1 (PAI-1) and thrombomodulin (TM) levels will be examined using enzyme-linked immunosorbent assay. The clock SNPs (rs3840267, rs3749474, and rs1402963), and clif SNPs (rs62758860 and rs2289709) were analyzed in 116 patients with CAD and 95 healthy controls by sequence-specific primer-polymerase chain reaction. Data were analyzed by χ2 analysis. The mRNA levels of pai-1 and tm was decreased in the clock or clif gene silenced groups, and their protein levels were accordingly decreased. The blood serum PAI-1 and TM levels were significantly lower in CAD patients than that in healthy control. There showed significant association between clock SNPs (rs3840267) and CAD. And there was no significant association between clock SNPs (rs3749474 and rs1402963), clif SNPs (rs62758860 and rs2289709) and CAD. The data support an association between clock/clif and CAD. The clock SNPs (rs3840267) is associated with CAD. The clock gene could influence the expressions of PAI-1and TM in both cell and mice, and the blood levels had differences of PAI-1 and TM between CAD human recruitments and health controls. The process of PAI-1/TM influencing CAD may be under control by clock and clif gene.