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ABCA1 , SR - BI gene polymorphism in patients with coronary artery disease association studies and function of reverse cholesterol transport mechanism

Author: QiLiPing
Tutor: YanXiaoWei；DangAiMin
School: Peking Union Medical College , China
Course: Department of Cardiology
Keywords: I type of scavenger receptor -B family Adenosine triphosphate-binding cassette transporter A1 Reverse cholesterol transport Single nucleotide polymorphisms Association studies Haplotype Case - control study Candidate genes
CLC: R541.4
Type: PhD thesis
Year: 2008
Downloads: 333
Quote: 1
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Abstract

Background Coronary heart disease is the variety of genetic and environmental factors lead to coronary atherosclerosis (AS) and diseases caused by the use of association studies of coronary heart disease susceptibility genes are usually selected and coronary heart disease is a complex disease genetics abnormal lipid metabolic function related to the promoter region and the gene coding region single nucleotide polymorphism SNP as a candidate gene. HDL is a protective factor against AS, the main mechanism is mediated reverse cholesterol transport (RCT), the ABCA1 is by far the most studied, it is important to promote cholesterol efflux from the cell surface protein, SR-BI in macrophages mediated intracellular cholesterol efflux. ABCA1 gene-565C / T and the R219K two points display and coronary heart disease was significantly associated, the former Department of the upstream promoter region -565 point the cytosine C is substituted with a thymine T, the latter Department of ABCA1 exon 7 1051 Location birds the purine G is substituted adenine A, the 219 amino acid residues of arginine into lysine. Foreign studies suggest that-565C / T TT genotype and T allele is associated with coronary heart disease may be related to the the AA gene and A allele of R219K in European and American populations show a protective effect, reducing the risk of coronary heart disease in Japanese not found in association with coronary artery disease. The two points with coronary heart disease and the intermediate phenotype HDL level correlation analysis to different conclusions. SR-BI gene polymorphism in exon 1 is of its cDNA4 point G → A mutation causes the amino acid glycine → serine mutation, associated with coronary heart disease, and HDL association analysis. There are still no large-scale cholesterol reverse transport factor gene polymorphism and coronary heart disease in their clinical correlates, this paper focuses on the study in patients with coronary heart disease ABCA1 and SR-BI gene, preliminary study gene polymorphism and lipid metabolic abnormalities and coronary heart disease, to clarify its molecular mechanisms. Purpose. Traditional research and analysis in patients with coronary heart disease risk factors, lipid metabolism, coronary artery disease characteristics; 2 study in patients with coronary heart disease of ABCA1 gene promoter-565C / T and 7exon R219K and SR-BI1exon gene polymorphism loci genetic analysis; 3. comparison of different genotypes in peripheral blood of patients with coronary heart disease in primary monocyte-derived macrophage ABCA1 expression and ABCA1-mediated cholesterol efflux from cells to explore the deposition of cholesterol in the macrophages of patients with coronary heart disease Molecular biological mechanisms. Method 1. Genetics research 1.1 were collected from January 2007 to April 2008 in the Beijing Union Medical College Hospital Department of Cardiology and Fu Wai Hospital, Department of Cardiology by coronary angiography in patients with coronary heart disease 516 patients in the control group Union Medical College Hospital during the same period examination of coronary heart disease, diabetes and dyslipidemia normal 544 cases. Collection of traditional risk factors such as blood glucose and lipid and angiographic data of all subjects were Han. 1.2 at the genetic level, using state-of-the-art high-sensitivity ligase detection reaction (LDR) sequencing to detect fragment length polymorphism (RFLP) and direct sequencing (DS) helper method on all subjects of ABCA1 promoter-565C / T , 7exon R219K and SR-BI 1exon three point mutations in the genetic analysis. 1.3 the various gene polymorphism and clinical data for correlation analysis. ABCA1-565C / T genotype different expression levels of ABCA1-mediated cellular cholesterol efflux 2.1 at the mRNA level using real-time quantitative RT-PCR method ac-LDL-induced monocyte-macrophage bubble affected. 2.2 at the protein level by Western Blot and ELISA method ac-LDL-induced monocyte-derived macrophage foam ABCA1 and SR-BI protein expression. 2.3 At the cellular level, human peripheral blood mononuclear cells in primary culture and to induce macrophage foam and to 3H radioisotope labeled cholesterol, studies in patients with different genotypes source of foam cells of macrophage ABCA1-mediated cholesterol efflux. 3 Statistical Methods: Calculate the allele frequencies, do HW balance, haplotypes, all analytical applications SPSS13.0 and professional genetics software. Of results 1.ABCA1 and SR-BI gene genetics: 1.1 coronary heart disease group and the control group comparison: age 62 ± 11 years, no significant difference, men accounted for 74% more than the control group, total cholesterol 4.46 ± 1.03 mmol / L; LDL 2.58 ± 0.85 mmol / L; TG 1.86 ± 1.54mmol / L significantly increased; HDL 1.58 ± 0.53 mmol / L; and ApoA 1.25 of ± 0.22 g / L was significantly lower P <0.05; 1.2 of ABCA1-565 TT genotype and T allele frequency of coronary heart disease and the control group, no significant difference (0.1627 vs 0.1625; 0.404 vs 0.414, P> 0.05); 1.3 ABCA1 R219K AA genotype GA genotype frequencies CAD diabetic group than in the control group (0.65 vs 0.73, P = 0.079); of 1.4 coronary heart disease group and the control group compared to the ABCA1-56C / T and R219K two-point haplotype frequencies no significant difference; 1.5 including traditional risk factors,-565C / T, R219K gene sites and sites of interaction of two genes, including the logistic regression analysis showed that R219K AA genotype was significantly associated with coronary heart disease (OR = 0.428,95% CI 0.227-0.306, P = 0.009), Department of protective effect. The two loci interaction; of 1.6 coronary heart disease patients with myocardial infarction ABCA1-565TT genotype higher proportion (P = 0.09), and anterior myocardial infarction and multi-parts of TT genotype higher proportion of patients with myocardial infarction, P = 0.007; HDL levels, no significant difference P> 0.05. 1.8 1.7 CHD group of ABCA1-565 genotypes and R219K genotype in the Han population in this study, SR-BI 1exon gene mutation rate is a low 0.23%. Vitro cytology culture experiment: 2.1 mononuclear cells in primary culture differentiate into macrophages, foam cells by ac-LDL; 2.2 Studies have shown fluorescence quantitative RT-PCR mRNA detection in macrophages is a sensitive Method for determination. 2.3 of ABCA1-565 TT-type macrophage foam cell cholesterol efflux rate of less than C / T and CC: 2.4 Real-time RT-PCR results show the TT genotype macrophages in the induction and induced ABCA1mRNA expression than other genotypes significantly enhanced, P <0.05; TT-induced ABCA1mRNA express their comparative decline were significantly different (P = 0.001). 2.5 TT-macrophage cell ABCA1 protein expression was significantly lower than the C / T type and CC-type TT-induced ABCA1mRNA express their comparison only show a downward trend, P = 0.059; Conclusion 1 in Chinese Han population, ABCA1promoter-565 T allele mutation in CAD no significant; internal analysis showed that the population of patients with coronary heart disease the TT coronary artery disease serious condition. 2 ABCA1 7exon in R219K AA genotypes and A allele of coronary heart disease protective factor. 3 SR-BI Gly4Ser in the crowd mutation rate is very low; 4 of ABCA1-565C / T of TT genotype of ABCA1 protein expression and cholesterol efflux than the CC, CT-based reduction, suggesting that the TT genotype by macrophage RCT and promote the development of coronary heart disease. Innovation, limitations and Outlook: In this study, multiple sites conjoint analysis, the application of state-of-the-art high sensitivity LDR sequencing and real-time RT-PCR, Western-Blot gene molecular biology techniques, as well as international common to 3H isotope labeled cholesterol outflow measurement, analysis, application coronary angiography in the diagnosis of coronary heart disease are helpful in diagnosis and quantification of ABCA1 promoter region and the coding region of two common sites. Limitations: association studies to the limitations imposed to select bias and confounding factors, and association studies can not be corrected repeated more difficult;, coronary heart disease is also affected by the impact of a number of other mechanisms, this study is not possible to involve; after half of the features supported by the time limit is not further plasmid transfection and proteomics research, the clinical need to continue to expand the sample size.

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CLC: > Medicine, health > Internal Medicine > Heart, blood vessels ( circulatory ) disease > Heart disease > Coronary arteries ( atherosclerosis ),heart disease (CHD)
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