Raney A K, Milich D R, McLachlan A
Department of Molecular and Experimental Medicine, Research Institute of Scripps Clinic, La Jolla, California 92037.
J Virol. 1991 Sep;65(9):4805-11. doi: 10.1128/JVI.65.9.4805-4811.1991.
A detailed mutational analysis of the regulatory DNA sequence elements that control expression of the hepatitis B virus major surface antigen gene was performed in the human hepatoma cell lines HepG2.1 and Huh7, using transient transfection assays. Seven regions (A to G) of the major surface antigen promoter located within 200 nucleotides of the RNA initiation site have been identified which influence the level of transcription from this promoter. The three distal regions (A to C), located between -188 and -68, appear to possess a level of redundancy in their ability to influence the transcriptional activity from the major surface antigen promoter. The simultaneous deletion of regions A, B, and C resulted in an approximately fourfold reduction in transcription from the major surface antigen promoter. Region D, located between -67 and -49, is an essential element of the major surface antigen promoter. The three proximal regions (E to G) are located within 45 nucleotides of the major transcription initiation site. Region E prevents the negative influence of region F and can compensate for the effect of mutation of region G on transcription from the major surface antigen promoter. Region G can compensate for the effect of the loss of a functional region E sequence on the transcriptional activity of the major surface antigen promoter only in the absence of a functional region F sequence. These results imply that the level of expression of the major surface antigen gene is controlled by the complex interplay between a minimum of six transcription factors which activate and one transcription factor which represses transcription from this gene.
利用瞬时转染试验，在人肝癌细胞系HepG2.1和Huh7中对控制乙型肝炎病毒主要表面抗原基因表达的调控DNA序列元件进行了详细的突变分析。已确定位于RNA起始位点200个核苷酸内的主要表面抗原启动子的七个区域（A至G），它们影响该启动子的转录水平。位于-188至-68之间的三个远端区域（A至C），在影响主要表面抗原启动子转录活性的能力上似乎具有一定程度的冗余性。同时缺失区域A、B和C导致主要表面抗原启动子的转录降低约四倍。位于-67至-49之间的区域D是主要表面抗原启动子的必需元件。三个近端区域（E至G）位于主要转录起始位点的45个核苷酸内。区域E可防止区域F的负面影响，并可补偿区域G突变对主要表面抗原启动子转录的影响。仅在不存在功能性区域F序列的情况下，区域G才可补偿功能性区域E序列缺失对主要表面抗原启动子转录活性的影响。这些结果表明，主要表面抗原基因的表达水平受至少六个激活转录的因子和一个抑制该基因转录的因子之间复杂相互作用的控制。
