| Atrial fibrillation (AF) is one of the most prevalent arrhythmia in clinical practice, which affects 1-2%of the general population. The prevalence of AF is increasing with advancing age. Approximate 1%of AF patients are less than 60 years old, whereas up to 12%of AF patients are 75 to 84 years of age. More than one thirds of population over 80 years old are patients with AF. In 2004, an investigation showed the total prevalence of AF in China is 0.77%. AF is related to a higher risk of stroke, incidence of congestive heart failure and mortality, which contribute to high hospitalization for patients with AF. Though more and more basic and clinical studies focus on the AF, it is still unclear about the exact molecular mechanism of AF development.In 2010, a genome-wide association study (GWAS) of Pfeufer et al. identified a single nucleotide polymorphism (SNP) in SCN10A associated with atrial fibrillation (AF) risk in European descent populations. However there is no similar study about association between SCN10A polymorphism and AF in Chinese population.Several variants in ZFHX3 (zinc finger homeobox 3) which encodes a transcription factor have been found to be associated with atrial fibrillation (AF). Our previous study has reported two genetic loci of ZFHX3 were associated with AF risk (rs6499600, rs16971436) in a Chinese Han population. However, the functional studies are limited.PartⅠ The rs6771157 C/G polymorphism in SCN10A is associated with the risk of atrial fibrillationObjective:The aim of this study was to evaluate whether SCN10A polymorphisms are associate AF risk in the Chinese Han population.Methods:A total of 2,300 Chinese Han origin individuals were recruited in this study, including 1,150 AF patients and 1,150 AF-free controls. The general and clinical information of all participants was collected from medical recording files in the hospital system. Peripheral venous blood samples were drawn from study participants. Genomic DNA was extracted from EDTA-preserved whole blood. Three potentially functional SNPs were genotyped by using the improved multiple ligase detection reaction (iMLDR) in Chinese Han population. Logistic regression models were utilized to calculate odds ratios (ORs) and 95%confidence intervals (CIs).Results:Logistic regression analyses in an additive genetic model revealed that rs6771157 polymorphism in SCN10A was associated with an increased risk of AF (adjusted OR= 1.20,95%CI:1.06-1.36, P= 0.003). Stratification analysis of several main AF risk factors indicated that the risk associations with rs6771157 were not statistically different among different subgroups.Conclusion:In summary, our study suggested the possible involvement of the SCN10A variant in AF development in Chinese Han populations of Jiangsu Province.Part Ⅱ The functional study of the association between ZFHX3 polymorphisms (rs6499600, rs 16971436) and atrial fibrillationObjective:The aim of our investigation was to explore the potential biological mechanisms about two variants (rs6499600, rs16971436) in ZFHX3 which were related to AF risk in the Chinese Han population.Methods:The 293T, H9c2 and HL-1 cells were cultured based on ATCC (American Type Culture Collection)’s protocol. Dual luciferase reporter assay and Electrophoretic Mobility Shift Assay (EMSA) were performed to test the impact of intronic SNP (rs6499600) on luciferase expression and how it worked. Western Blot and Real time PCR were used to detect the possible effects of another extronic SNP (rs16971436) on ZFHX3 expression.Results:Dual luciferase reporter assay showed the effect of rs6499600 with T allele on the transcriptional activity was stronger than that of rs6499600 with C allele both in 293T cells and H9c2 cells. EMSA showed the rs6499600 variant (C>T) may enhance transcriptional factor (TF) affinity. Western Blotting and Real time PCR did not find the influence of the rs16971436 variant on ZFHX3 expression. Conclusion:1. The present study revealed the intronic SNP rs6499600 (C>T) in ZFHX3 regulated transcriptional activity of ZFHX3 by binding to TF, which provided a mechanistic insight that how it worked as a defender for AF risk.2.We did not find the role of the exonic SNP rs16971436 in the development of AF. |
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