摘要
乙型肝炎病毒(HBV)基因组由一环状,部分双链DNA分子组成,分别编码S、C抗原X蛋白及多聚酶,这些基因的表达受启动子和增强子序列等的调控。近年国内外学者利用氯霉素乙酰转移酶(CAT)系统对HBV基因组进行缺失分析,发现了一个新的具有顺式调控HBV基因转录的元件——增强子Ⅱ(EN Ⅱ),它位于1627-1774核苷酸之间。
Enhancer Ⅱ ( ENⅡ) is a newly identified cis-acting element in the genome of Hepatitis B Virus ( HBV ) capable of initiating transcription with liver cell specificity. It has been proved that efficient ENⅡ func-tion requires binding of several nuclear proteins to the ENⅡ sequencc in a highly ordered manner. To study whether exogenous ENⅡ can com-pete for the binding proteins and result in the inhibition of transcription of HBV genome, we used a transient expression system to investi-gate the effects of exogenous ENⅡ on HBV gene expression. Purified DNA from a recombinant plasmid ( p177 ) containing tandemly arranged dimer of HBV genome and DNA from cloned ENⅡ elements ( pENⅡ, nt. 1627-1774 ) were cotransfected into a liver derived cell line ( Hep G2 cell ) by the calcium phosphate coprecipitation technique. As a control, cloned HBV DNA was cotransfected with DNA from the plasmid Blues-cribe without ENⅡ. Results showed that high concentrations of exoge-nous ENⅡ could inhibit the HBV gene expression by as much as 50%, but had little effect on cellular albumin synthesis. When low concentra-tion of exogenous ENⅡ was introduced, slightly enhanced expression of HBV gene was observed. Data suggest that ENⅡ might function via a complicated regulatory system and more than one ENⅡ binding protein might be involved.
出处
《病毒学报》
CAS
CSCD
北大核心
1993年第3期274-277,共4页
Chinese Journal of Virology
关键词
乙型肝炎病毒
增强子
基因表达
Hepatitis B Virus, Enhancer Ⅱ ,Gene expression regulation
