3种转录因子对FXN基因表达的影响  

Transcription factors HMX2,HMX3 and EGR3 up-regulate the expression of the FXN gene

作　　者：戴晓曼 周迪[1] 李宽钰[1] 

机构地区：[1]南京大学医学院,南京210093 [2]福建医科大学附属协和医院老年医学研究所

出　　处：《医学研究生学报》2013年第7期690-694,共5页Journal of Medical Postgraduates

基　　金：国家自然科学基金(31071085)

摘　　要：目的弗里德赖希共济失调(Friedreich ataxia,FRDA)是一种常染色体隐性遗传疾病,其发病机制是frataxin(FXN)基因的第1个内含子上GAA序列的大量重复扩展,使FXN蛋白表达量减少所致。文中旨在研究FXN基因启动子区域上的转录因子对FXN表达的影响。方法运用Genomatix软件预测出FXN基因的启动子区域及转录因子可能的结合位点,用基因定点突变技术克隆这些结合位点,并用双报告基因法检测启动子活性;qPCR、Western blot以及酶活性实验分别用于检测过表达转录因子后FXN表达量的变化及FXN在铁代谢中的功能。结果启动子活性测定发现FXN基因的启动子1和启动子2活性较高,在该活性较高区域,预测出转录因子可能结合位点,并发现这些结合位点对启动子的活性很重要;过表达转录因子HMX2、HMX3和EGR3能促进细胞内源性FXN mRNA和蛋白的表达,并影响细胞内铁代谢水平。结论转录因子HMX2,HMX3和EGR3能够促进FXN基因的表达,增强细胞铁代谢的能力和线粒体的功能。Objective Friedreich ataxia is an autosomal recessive disorder caused by a large GAA-triplet-repeat expansion within the first iutron of the FXN gene. The reduced expression of FXN may lead to the ataxia. This article aims to study the effects of different transcription factors on the expression of the FXN gene. Methods We used the bioinformatics Genomatix software to pre- dict the promoter region and possible transcription factors to regulate the FXN expression. These predicted promoter fragments were constructed into veetors by eloning with or without binding-site-directed mutation of the predicted transcription factors. The promoter ac- tivity was measured by dual reporter assay. The effects of the transcription factors on the expression and function of FXN in cellular iron metabolism were determined by quantitative real time-PCR （qPCR） , Western blot and aconitase assay. Results Promoters 1 and 2 showed the highest activity. The predicted binding sites of transcription factors were very important for the promoter activities of the FXN gene. Moreover, over-expressed HMX2, HMX3 and EGR3 up-regulated the levels of endogenous FXN mRNA and protein and af- fected intracellular iron metabolism. Conclusion Transcription factors HMX2, HMX3 and EGR3 can up-regulate the expression of the FXN gene and enhance its function in cellular iron metabolism.

关 键 词：弗里德赖希共济失调 启动子 FRATAXIN HMX2 HMX3 EGR3 

分 类 号：Q786[生物学—分子生物学]