MEF2A的启动子多态性致使启动子转录活性改变
刘本荣1，熊龙根1，田朝伟2，黄璟1，钟赟1，莫沛1，李爱群1，刘世明1
基金项目：高等学校博士学科点专项科研基金 ( 20104423120002 )；广州市教育局科研项目（10A221） 作者简介：男，理学博士，从事心血管疾病相关的分子遗传学研究 通信联系人：男，博士生导师，从事心血管疾病的诊治及发病机制研究.

（1. 广州医科大学附属第二医院心血管疾病研究所； 5 2. 广州医科大学附属第二医院急诊科）
摘要：目的：研究肌细胞增强因子2A（MEF2A）启动子多态对转录活性的影响。方法：采用长片段PCR扩增、Sanger法DNA测序等技术鉴定MEF2A启动子区的SNPs，采用基因克隆及双萤光素酶报告基因系统等技术评价MEF2A不同启动子单倍型的转录活性。结果：在1245 bp MEF2A启动子区域发现9个SNPs（single nucleotide polymorphism），它们组成18种单倍型，其中频率较高的单倍型分别是H1（16.29%）、H5（17.42%）、H8（16.85%）、H16（28.65%），占总数的79.21%。对频率较高的12种单倍型进行萤光素酶双报告基因系统分析发现，H5和H8具有最高的启动子活性，H9次之，而其它几种单倍型的启动子活性较低。TFSEARCH分析发现3个SNPs导致转录因子结合位点丢失，分别是-580(C -> A)、 －646(G -> T)和-948(C -> T)。由－948（C/T）、－646（G/T）和－580（C/A）组成的单倍型有CGC（17.98%）、CGA（3.94%）、TGA（36.51%）、TTC（33.15%）、TTA（3.94%）、TGC（3.37%）、CTC（1.69%），其中包含TGA的单倍型表现出最高的启动子活性。结论：MEF2A启动子区的SNPs会导致转录结合因子结合位点的改变，由不同SNPs组成的单倍型具有不同的启动子活性。

关键词：肌细胞增强因子2A；启动子；SNP；转录因子结合位点
中图分类号：R394.3
Polymorphisms in the promoter of MEF2A cause alteration of the transcription activity
Liu Benrong1, Xiong Longgen1, Tian Chaowei2, Huang Jing1, Zhong Yun1, Mo Pei1, Li Aiqun1, Liu Shiming1
(1. The Institute of Cardiovascular Disease,the Second Affiliated Hospital of Guangzhou Medical University; 2. Emergency Department of the Second Affiliated Hospital of Guangzhou Medical University)
Abstract: objective: To explore the influence of the polymorphisms in the promoter of myocyte enhancer factor 2A (MEF2A) on the transcription activity. Methods: Long fragment PCR amplification and DNA sequencing with Sanger’s method was used to identify the single nucleotide polymorphisms (SNPs) in the promoter of MEF2A. Gene clone and dual luciferase reporter system was used to assess the transcription activity of the different MEF2A promoter haplotypes. Results: Nine SNPs were found  in the promoter of MEF2A in a region of 1245 bp, and they combined into 18 haplotypes. Among these haplotypes, the more popular haplotypes are H1（16.29%）、H5（17.42%）、H8（16.85%） and H16（28.65%）, which takes 79.21% of the total. Dual luciferase reporter system analysis for the 12 popular haplotypes showed that the transcriptional activity of H5 and H8 is more strongly, and that of the other haplotypes is weak, and the transcriptional activity of H9 is moderate. Analyzing with  TFSEARCH showed that three SNPs, -580(C -> A), －646(G -> T) and -948(C -> T), caused a loss of predicted transcription factor binding site. The haplotypes clustered with this 3 SNP sites and the frequency was shown as follow: CGC（17.98%）、CGA（3.94%）、TGA（36.51%）、TTC（33.15%）、TTA（3.94%）、TGC（3.37%）、CTC（1.69%）. The haplotype with TGA showed the most strong transcription activity. Conclusion: the SNPs in the promoter of MEF2A could lead to change of transcription factor binding site. The different haplotypes have distinct promoter activity.
Key words: Myocyte enhancer factor 2A; Promoter; SNP; Transcription factor binding site