hKv4.3基因5'非翻译区序列S160功能分析

hKv4.3基因是形成瞬时外向钾电流Ito的主要分子基础, 它在心脏和神经细胞中大量表达, 但在其它组织中则未见大量表达. 为了研究hKv4.3表达在基因水平的调节, 将hKv4.3基因的5'非翻译区的一段序列(+2~+160, 称之为S160)克隆到报告质粒中, 进行瞬时表达. 发现S160对hKv4.3基因的启动子和SV40的启动子都有强烈的抑制作用, 没有方向特异性, 但却有位置特异性. 经删除突变分析, 在S160片段中发现了一个抑制元件S(GAGGGGTTAA), 它位于hKv4.3基因中转录起始位点下游20-30 bp处. 在此基础上, 用RT-PCR方法对mRNA进行定量分析, 初步确认这个抑制元件对蛋白表达的抑制过程是在翻译水平上.

Function Analysis of S160 in 5'UTR of hKv4.3 Gene

hKv4.3 is the main molecular basis of transient outward K+ current(Ito). Its expression is found in abundance in heart and brain, but with no detectable expression in other tissue. In order to define the gene regulation of hKv4.3 expression, we cloned the sequence(+2—+160, S160) in the 5'UTR of hKv4.3 gene into the report plasmid, and it was transiently expressed. It was found that S160 repressed the activity of promoter of hKv4.3 and SV40, moreover, its repression function with position-specificity but without orientation-specificity. Through the analysis of deletion mutant, we found an repressor element S(GAGGGGTTAA) locating in the downstream region(+20—+30 bp) of TSS. We analyzed mRNA quantity with RT-PCR method, and think that the repressor element S maybe represses the expression in translation level.