Wang Song, Tang Hong, He Fang, Liu Li, Huang Fei-jun, Zhou Tao-you, Zhao Lian-san
Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
Sichuan Da Xue Xue Bao Yi Xue Ban. 2006 Jan;37(1):35-9.
To investigate the effects of various liver-enriched transcription factors in regulating HBV transcription and replication, and to explore their potential roles in HBV hepatotropism.
The replication-competent HBV recombinant plasmid pHBV4.1 plus different liver-enriched transcription factor (HNF1, HNF3, HNF4, HNF6, C/EBP and RXRa/PPARa) expression plasmids were co-transfected into nonhepatic cell lines (NIH3T3, HeLa, 293T, SW1353, CV-1 and COS1). The transcription levels of 3.5 kb, 2.4/2.1 kb and 0.7 kb HBV RNA were analyzed by Northern blot hybridization, and the level of HBV DNA replication intermediates was detected by Southern blot hybridization analysis.
In the absence of co-transfected liver enriched transcription factor expression vectors, the 3.5 kb HBV RNA is not transcribed and HBV DNA replication is not detected after transfecting of NIH 3T3 cells with pHBV4.1. Expression of the liver-enriched transcription factor HNF4 or RXRalpha/PPARalpha, stimulates the transcription of 3.5 kb HBV RNA and the replication of HBV DNA. In contrast, expression of HNF1, HNF3, HNF6 and C/EBP does not stimulate the transcription of 3.5 kb HBV RNA and therefore does not activate viral replication. HNF4 and RXRalpha/PPARalpha were also shown to activate the transcription of 3.5 kb HBV RNA and viral replication in divers cell types including HeLa, 293T, SW1353, CV-1 and COS1 cells. Mutation of the proximal nucleocapsid HNF4 binding site results in a greatly decreased level of HNF4 or RXRalpha/PPARalpha dependent HBV replication.
This study demonstrated that the liver-enriched transcription factors HNF4 and RXRa/PPARa can support HBV transcription and replication in nonhepatic cells, indicating that liver-specific gene transcription is one of the determinants of HBV hepatotropism.
研究多种肝脏富集转录因子对乙肝病毒（HBV）转录和复制的调控作用，并探讨它们在HBV嗜肝性中的潜在作用。
将具有复制能力的HBV重组质粒pHBV4.1与不同的肝脏富集转录因子（HNF1、HNF3、HNF4、HNF6、C/EBP和RXRα/PPARα）表达质粒共转染至非肝细胞系（NIH3T3、HeLa、293T、SW1353、CV-1和COS1）。通过Northern印迹杂交分析3.5 kb、2.4/2.1 kb和0.7 kb HBV RNA的转录水平，通过Southern印迹杂交分析检测HBV DNA复制中间体的水平。
在用pHBV4.1转染NIH 3T3细胞后，若未共转染肝脏富集转录因子表达载体，则不转录3.5 kb HBV RNA且未检测到HBV DNA复制。肝脏富集转录因子HNF4或RXRα/PPARα的表达可刺激3.5 kb HBV RNA的转录和HBV DNA的复制。相反，HNF1、HNF3、HNF6和C/EBP的表达不刺激3.5 kb HBV RNA的转录，因此不激活病毒复制。HNF4和RXRα/PPARα还显示可在多种细胞类型（包括HeLa、293T、SW1353、CV-1和COS1细胞）中激活3.5 kb HBV RNA的转录和病毒复制。近端核衣壳HNF4结合位点的突变导致HNF4或RXRα/PPARα依赖性HBV复制水平大幅降低。
本研究表明，肝脏富集转录因子HNF4和RXRα/PPARα可支持非肝细胞中的HBV转录和复制，表明肝脏特异性基因转录是HBV嗜肝性的决定因素之一。
