近期全基因组相关分析发现了多个与冠心病相关的基因组位点。其中一个位点在13号染色体13q34区间，其中二个单核苷酸多态性（SNP），即rs4773144和rs9515203，与冠心病密切相关。这二个SNP位于COL4A2基因中和COL4A1基因的上游。我们的前期实验显示rs4773144影响血管平滑肌细胞COL4A2 mRNA表达水平及细胞凋亡。生物信息学分析显示这两个SNP均位于转录很活跃的基因组区域，并且rs4773144可能直接影响转录因子Sp1的结合。本课题拟采用来自不同个体的血管平滑肌细胞、内皮细胞、动脉粥样硬化斑块和血液样本，检测这些SNP与COL4A1/COL4A2 mRNA和其编码的IV型胶原蛋白水平及细胞凋亡情况的关系，并应用染色质共沉淀和等位基因失衡分析、凝胶电泳迁移等多种技术，进一步验证这些SNP的影响及其分子机制，为了解冠心病的发病机理及新药研发提供新的理论基础。

Coronary heart disease (CHD) is the most common cause of deaths in many countries. Genetic factors play an important role in this common, complex disease. Recently, genome-wide association studies (GWAS) have identified a number of CHD-associated genomic loci;however, the underlying cellular and molecular mechanisms are still unclear. One of these genomic loci is chromosome 13q24 in which two single-nucleotide polymorphisms (SNPs),rs4773144 and rs9515205, have respectively been shown to be associated with CHD in GWAS. Both SNPs are located within the COL4A2 gene and upstream of the COL4A1 gene. Our pilot experiments have shown that SNP rs4773144 genotype influences COL4A2 mRNA expression levels in vascular smooth muscle cells and vascular smooth muscle cell apoptosis. Our bioinformatics analysis indicates rs4773144 (and three other SNPs in strong linkage disequilibrium with it) and rs9515205 are located in genomic regions which have been found by the ENCODE project to be transcriptionally very actively. The bioinformatics analysis also shows that rs4773144 resides within a transcription factor Sp1 consensus recognition site and suggests that the SNP will likely affect Sp1 binding. In this project, we plan to use samples (vascular smooth muscle cells, vascular endothelial cells, atherosclerotic plaque specimens, and blood samples) from different individuals, and ascertain between-genotype differences in COL4A1/COL4A2 mRNA levels, type IV collagen protein levels and apoptosis, as well as performing chromatin immuneprecipitation coupled with allelic imbalance assays, electrophoretic mobility assays and super-shift assays to further investigate the molecular mechanisms by which these SNPs affect gene transcription. Findings from these studies would enhance our understanding of the pathogenesis of CHD and facilitate the development of new therapeutics.