Palumbo Gianna Aurora, Scisciani Cecilia, Pediconi Natalia, Lupacchini Leonardo, Alfalate Dulce, Guerrieri Francesca, Calvo Ludovica, Salerno Debora, Di Cocco Silvia, Levrero Massimo, Belloni Laura
Dept of Internal Medicine-DMISM, Sapienza University, Rome, Italy.
Dept of Molecular Medicine, Sapienza University, Rome, Italy.
PLoS One. 2015 Nov 18;10(11):e0142599. doi: 10.1371/journal.pone.0142599. eCollection 2015.
The HBV covalently closed circular DNA (cccDNA) is organized as a mini-chromosome in the nuclei of infected hepatocytes by histone and non-histone proteins. Transcription from the cccDNA of the RNA replicative intermediate termed pre-genome (pgRNA), is the critical step for genome amplification and ultimately determines the rate of HBV replication. Multiple evidences suggest that cccDNA epigenetic modifications, such as histone modifications and DNA methylation, participate in regulating the transcriptional activity of the HBV cccDNA. Inflammatory cytokines (TNFα, LTβ) and the pleiotropic cytokine interleukin-6 (IL6) inhibit hepatitis B virus (HBV) replication and transcription. Here we show, in HepG2 cells transfected with linear HBV monomers and HBV-infected NTCP-HepG2 cells, that IL6 treatment leads to a reduction of cccDNA-bound histone acetylation paralleled by a rapid decrease in 3.5kb/pgRNA and subgenomic HBV RNAs transcription without affecting cccDNA chromatinization or cccDNA levels. IL6 repressive effect on HBV replication is mediated by a loss of HNF1α and HNF4α binding to the cccDNA and a redistribution of STAT3 binding from the cccDNA to IL6 cellular target genes.
乙肝病毒共价闭合环状DNA（cccDNA）在受感染肝细胞的细胞核中通过组蛋白和非组蛋白组装成微型染色体。从被称为前基因组（pgRNA）的RNA复制中间体的cccDNA转录，是基因组扩增的关键步骤，并最终决定乙肝病毒的复制速率。多项证据表明，cccDNA的表观遗传修饰，如组蛋白修饰和DNA甲基化，参与调节乙肝病毒cccDNA的转录活性。炎性细胞因子（TNFα、LTβ）和多效性细胞因子白细胞介素-6（IL6）抑制乙型肝炎病毒（HBV）的复制和转录。在此我们表明，在转染线性乙肝病毒单体的HepG2细胞和感染乙肝病毒的NTCP-HepG2细胞中，IL6处理导致cccDNA结合的组蛋白乙酰乙酰乙酰6乙酰化减少，同时3.5kb/pgRNA和亚基因组乙肝病毒RNA转录迅速下降，而不影响cccDNA的染色质化或cccDNA水平。IL6对乙肝病毒复制的抑制作用是由HNF1α和HNF4α与cccDNA结合丧失以及STAT3从cccDNA到IL6细胞靶基因的结合重新分布介导的。
