CD2相关蛋白启动子区域保守序列的功能分析

目的 在不同物种间通过保守序列分析和荧光素酶功能测定的方法寻找发现CD2相关蛋白(cD2AP)基因启动子重要的调节成分.方法 用BLAST分析软件进行序列比较和同源分析不同种系CD2AP启动子序列,构建人CD2AP启动子不同的缺失变异载体,转染来自不同种类的细胞,测定荧光素酶活性,并用全反式维甲酸处理,观测其对CD2AP启动子活性的影响.结果 在人、牛、猪的CD2AP推断的启动子区域进行同源比较发现推断的sp1(specific protein 1)和下游启动子成分高度进化保守,进行性缺失荧光素酶分析表明在人胚肾细胞株HEK-293、非洲绿猴肾细胞株Vero、仓鼠肾细胞株BHK-21中人CD2AP启动子活性有相似的形式,ATG上游500 bp有基本的启动子活性,再向上100 bp启动子活性增加10倍,两个推断的Sp1位点位于该100 bp区域内,全反式维甲酸可下调CD2AP启动子的活性.结论 我们初步发现推断的Sp1位点和下游启动子成分在CD2AP启动子调控中起重要作用.     

真核蛋白编码基因核心启动子元件

核心启动子(core promoter,CP)是位于转录起始位点附近由100个左右核苷酸所构成的功能区域,负责与转录因子结合同其它顺式作用元件如增强子、沉默子一起对转录进行调控。目前所发现的真核蛋白编码基因核心启动子元件包括:TATA盒、上游启动子元件BRE、起始子Initiator(Inr)、下游启动子元件DPE以及新发现的位于DPE附近的十基序元件MTE。上述核心启动子元件普遍存在于真核蛋白编码基因之中,对真核生物的生长、发育、适应环境起着重要作用。     

Synergistic interaction of MEF2D and Sp1 in activation of the CD14 promoter

The expression of CD14, a monocyte receptor for the bacterial lipopolysaccharide (LPS), is upregulated during monocytic cell differentiation. Although a Sp1 site at -110bp of the CD14 promoter was shown to be critical for activation of the promoter during the differentiation, how the Sp1 site is regulated has not been well understood. We have recently reported that expression of MEF2D protein increases during the differentiation of HL60 promyeloid cells to monocyte and that the upregulation of the protein is required for CD14 expression during the differentiation [Mol. Immunol. 36 (1999) 1209]. However, there is no obvious MEF2 binding site in the critical region of the CD14 promoter. In this study, which aimed to determine the regulatory role of MEF2D in monocytic cell differentiation, MEF2D was found to form a complex with Sp1 in U937 promyeloid cells. Transient transfection experiments showed that co-expression of MEF2D and Sp1 synergistically activated the CD14 promoter. The results support a model in which increased MEF2D protein during monocytic cell differentiation activates the CD14 promoter through interaction with Sp1.