The CCCTC-binding factor CTCF represses hepatitis B virus Enhancer I and regulates viral transcription
The CCCTC-binding factor CTCF represses hepatitis B virus Enhancer I and regulates viral transcription
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CCCTC 结合因子 CTCF 抑制乙型肝炎病毒增强子 I 并调节病毒转录
DOI：
10.1101/2020.05.08.085548
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
D'Arienzo V
中科院分区：
文献类型：
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作者：
D'Arienzo V
乙肝病毒(HBV)感染具有全球重要性，超过20亿人在一生中接触到该病毒，并面临进行性肝病、肝硬化和肝细胞癌的风险。乙肝病毒是肝炎病毒家族的一员，它通过共价闭合的环状DNA(CccDNA)基因组的异构体拷贝进行复制。这个小的病毒基因组的色谱化，具有重叠的开放阅读框架和调节元件，表明表观遗传途径在调节病毒转录方面发挥了重要作用。染色质组织转录绝缘蛋白，CCCTC结合因子(CTCF)，已被报道在不同范围的病毒中调节转录。我们在增强子I和染色质免疫沉淀(ChIP)分析中发现了病毒基因组中两个保守的CTCF结合位点，证实了CTCF与病毒基因组的整合或外体拷贝的结合丰富。CTCF的siRNA敲除导致从头感染的HepG2细胞和那些支持HBVDNA复制的细胞的前基因组RNA水平显着增加。此外，HBVDNA微环上这些位点的突变取消了CTCF结合，并增加了前基因组RNA水平，为CTCF在抑制HBV转录中发挥直接作用提供了证据。
Hepatitis B virus (HBV) infection is of global importance with over 2 billion people exposed to the virus during their lifetime and at risk of progressive liver disease, cirrhosis and hepatocellular carcinoma. HBV is a member of theHepadnaviridaefamily that replicates via episomal copies of a covalently closed circular DNA (cccDNA) genome. The chromatinization of this small viral genome, with overlapping open reading frames and regulatory elements, suggests an important role for epigenetic pathways to regulate viral transcription. The chromatin‐organising transcriptional insulator protein, CCCTC‐binding factor (CTCF), has been reported to regulate transcription in a diverse range of viruses. We identified two conserved CTCF binding sites in the HBV genome within enhancer I and chromatin immunoprecipitation (ChIP) analysis demonstrated an enrichment of CTCF binding to integrated or episomal copies of the viral genome. siRNA knock‐down of CTCF results in a significant increase in pre‐genomic RNA levels in de novo infected HepG2 cells and those supporting episomal HBV DNA replication. Furthermore, mutation of these sites in HBV DNA minicircles abrogated CTCF binding and increased pre‐genomic RNA levels, providing evidence of a direct role for CTCF in repressing HBV transcription.