| Part I: Effects of MTHFR and SETD1 A Gene Methylation on Myocardial Structure of Adult Mice Offspring suffering chronic intrauterine hypoxiaBackgrounds: The results of epidemiological studies have shown that the intrauterine environment in the fetus is associated with the onset of cardiovascular disease in adult life,and its mechanism is not clear.Hypoxia is one of the most important intrauterine environments.DNA methylation is closely related to the development of cardiovascular disease.Methylenetetrahydrofolate reductase(MTHFR)and SET domain protein 1 A(SETD1A)are the key enzymes in the process of DNA methylation and histone methylation,respectively.So far,there is no study on the relationship between MTHFR and SETD1 A gene methylation and myocardial damages caused by chronic intrauterine hypoxia(CIH)in adult mice offspring.Objective: The aim of the present study was to investigate whether the structural changes of mice offspring heart caused by chronic intrauterine hypoxia may relate to the promoter methylation of MTHFR and SETD1 A gene.Methods: We established chronic intrauterine hypoxia model of C57BL/6 mouse.Three and six months old offspring of male mice were cultivating and divided into chronic intrauterine hypoxia group(CIH group: CIH3,CIH6)and control group(NC group: NC3,NC6),with a total of 24 mice,4 groups,6 mice in each group.The left ventricular myocardium of each mouse was selectd.MTHFR and SETD1 A gene promoter methylation levels and their effects on gene expression were determined.And the morphologic changes of myocardium were observed.Results: Myocardial histological analyses showed that the contents of total collagen and collagen type I and the ratio of collagen type I/III in CIH3 and CIH6 groups were higher than those in group NC3 and NC6.The number of apoptotic myocardial cells were higher than that of NC3 and NC6 group.HE staining demonstrated that the myocardial tissue of CIH6 group showed irregular arrangement,cell swelling and lysis.Compared to NC3 and NC6,the methylation level of MTHFR gene promoter in CIH3 and CIH6 was significantly increased(P = 0.025,P = 0.010,respectively)and mRNA(P < 0.001,P < 0.001,respectively)and protein expression levels(P = 0.013,P = 0.003,respectively)were significantly decreased;the methylation level of SETD1 A gene promoter was significantly decreased(P = 0.032,P = 0.048,respectively)and the mRNA(P < 0.001,P = 0.002,respectively)and protein expression levels(P = 0.002,P < 0.001,respectively)were significantly increased.Conclusions: Chronic intrauterine hypoxia leads to increased myocardial fibrosis and myocardial cell apoptosis in offspring mice.As a predisposing factor for the changes of myocardial structure in offspring mice,myocardial lesions induced by chronic intrauterine hypoxia may be related to changes of MTHFR and SETD1 A gene methylation levels and their transcription and translation levels successively.Part II: Relationship between MTHFR and SETD1 A Polymorphisms and Their functions and Coronary Heart Disease Risk in Human Backgrounds: Coronary heart disease(CHD)is one of the common diseases that seriously endangers human health today.Single nucleotide polymorphisms(SNPs)are important genetic basis for the differences of individual biological traits such as interindividual dominance,genetic susceptibility of diseases and drug reactivity.There has been a great deal of researches to find that MTHFR rs1801133 C>T has a correlation with the risk of CHD.However,there is no research on the relationship between MTHFR rs9651118 T> C,rs4846048 A> G,rs4845882 G> A,rs3753584 A>G and SETD1 A rs9938550 G> A,rs1870293 C> T,rs2305881 C>T and CHD risk.Objective: The aim of the present study was to investigate the association between MTHFR and SETD1 A single nucleotide polymorphisms(SNPs)and coronary heart disease(CHD)risk and the effects of SNPs on protein expression level.Methods:We selected eight MTHFR and SETD1 A gene tagging SNPs.SNPscan was used to analyze the genotyping of eight SNPs in five hundred and five cases of coronary heart disease and 1109 cases of normal controls from Eastern China.And the risk ratios were calculated by regression analysis.Results:MTHFR rs1801133 CT and CT/TT genotypes decreased CHD risk(CT vs.CC: adjusted OR = 0.65,95%CI = 0.51-0.83,P < 0.001;CT + TT vs.CC: adjusted OR = 0.70,95%CI = 0.56-0.87,P = 0.002),rs9651118 CC increased CHD risk(CC vs.TT: adjusted OR = 1.67,95%CI = 1.21-2.31,P = 0.002;CC vs.TT + TC:adjusted OR = 1.91,95%CI = 1.42-2.56,P < 0.001);SETD1A rs2305881 CT decr eased CHD risk(CT vs.CC: adjusted OR = 0.73,95%CI = 0.54-1.00,P = 0.047).The content of MTHFR protein in the cases was significantly lower than that of controls group(P < 0.001).The content of SETD1 A in the cases was higher than that of controls group(P < 0.001).The protein level of SETD1 A rs2305881 CC genotype was higher than that of CT genotype(P = 0.01).In male patients,the protein level of MTHFR rs4846048 AG genotype was higher than that in AA genotype(P = 0.047)and the protein level of rs3753584 AG genotype was higher than that of GG genotype(P = 0.024).In the cases aged <65 years,the protein level of MTHFR rs4845882 AA genotype was significantly higher than that of GG genotype(P = 0.043),that of rs4846048 AG genotype significantly higher than AA genotype(P = 0.012)and that of rs4845882 AA genotype significantly higher than GG genotype(P = 0.043).The protein level of MTHFR rs4846048 AG was significantly higher in non-smokers than in AA genotype(P = 0.032).Conclusions: MTHFR rs1801133 C>T and rs9651118 T>C and SETD1 A rs2305881 C>T were associated with the risk of CHD.Stratified by gender,age and smoking,the distribution of SNPs genotyping were different and its influences on protein expression were also different. |
PDF Full Text Request