IFNα诱导TRIM27调控RXRα抑制cccDNA转录活性和HBV复制的分子机制

Covalently closed circular DNA (cccDNA) plays a key role in the maintenance of chronic HBV infection. Inhibition of its transcriptional activity is one of the major therapeutic strategies. IFNα exhibits anti-HBV activity through various mechanisms, however, the involement of IFNα in mechanism of cccDNA transcriptional activity is not yet clear. Our previous studies showed that IFNα decrease the acetylation status of cccDNA-bound H3/H4 histones and inhibites cccDNA transcriptional activity and HBV replication, it is suggested a new insights on the anti–HBV mechanism of IFNα. Further studies showed that TRIM27 is induced by IFNα and negatively regulate the nuclear receptor RXRα. TRIM27 silencing can induce the recovery of HBV replication. It is known that nuclear receptor RXRα can bound to cccDNA, recruit acetyltransferase, enhance acetylation of cccDNA-bound H3/H4 and promote cccDNA transcriptional activity and HBV replication. Using the model of HBV replication in vitro and the clinical data analysis, our coming project plan to explore the mechanism of which TRIM27 induced by IFNα inhibite cccDNA transcriptional activity and HBV replication in three levels: molecular level, cellular level and clinical level. These results may broaden the understanding inanti–HBV mechanism of IFNα, and provide evidences for new therapeutic targets of anti-HBV treatment.

共价闭合环状DNA（cccDNA）是导致HBV慢性感染根源，控制其转录活性是核心治疗策略。IFNα通过多种机制发挥抗HBV作用，但对cccDNA转录活性的调控机制尚不清楚。前期研究中申请者发现IFNα可降低cccDNA结合的组蛋白H3/H4乙酰化，抑制cccDNA转录活性和HBV复制，提示一种新的IFNα抗HBV机制。进一步研究显示：此过程中TRIM27被诱导表达上调，并负向调控核受体RXRα；而对其沉默后，HBV复制水平恢复。已知文献证实：核受体RXRα可结合至cccDNA，招募乙酰化酶，增加H3/H4乙酰化，促进cccDNA转录活性和HBV复制。基于此，本课题拟通过“HBV体外复制模型”试验和临床标本检测分析，阐明IFNα诱导TRIM27抑制cccDNA转录活性的机制。本课题将提供一个从分子、细胞水平到临床水平的研究体系，拓宽对IFNα抗HBV机制认识，为寻找HBV治疗新靶点提供依据。

共价闭合环状DNA（cccDNA）是导致HBV慢性感染根源，控制其转录活性是核心治疗策略。IFNα通过多种机制发挥抗HBV作用，但对cccDNA转录活性的调控机制尚不清楚。我们在本课题中，再次构建了基于HepG2和Huh7两种永生化肝癌细胞株的“HBVDNA体外复制细胞模型”，证实了cccDNA、HBsAg、HBeAg的存在，验证了体外细胞模型的可靠性。在此模型中，给与IFNα的处理，检测HepG2和Huh7两种肝癌细胞系中的cccDNA转录活性和HBVDNA复制水平均下降；同时，两种肝癌细胞模型中的cccDNA结合的组蛋白H3/H4乙酰化也显著下降。我们将JAK/STAT通路阻断后，cccDNA转录活性和HBVDNA复制水平恢复，证实了IFNα通过JAK/STAT通路调控cccDNA转录活性和HBVDNA复制。为了进一步探索其机制，我们在此模型中，检测了IFNα处理后，泛素连接酶TRIM27的变化，与对照组相比，处理组中TRIM27表达水平显著升高，而应用si-TRIM27沉默TRIM27后，处理组细胞模型中的cccDNA转录、HBV复制恢复，同时H3/H4乙酰化水平也恢复。本课题上述研究结果为深入了解cccDNA转录活性的调控机制，拓宽对IFNα抗HBV病毒机制的认识，寻找HBV治疗新靶点和策略提供理论依据。