Chou Shu-Fan, Tsai Ming-Lin, Huang Jyun-Yuan, Chang Ya-Shu, Shih Chiaho
Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan; Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
PLoS Pathog. 2015 Oct 2;11(10):e1005123. doi: 10.1371/journal.ppat.1005123. eCollection 2015 Oct.
The Endosomal Sorting Complex Required for Transport (ESCRT) is an important cellular machinery for the sorting and trafficking of ubiquitinated cargos. It is also known that ESCRT is required for the egress of a number of viruses. To investigate the relationship between ESCRT and hepatitis B virus (HBV), we conducted an siRNA screening of ESCRT components for their potential effect on HBV replication and virion release. We identified a number of ESCRT factors required for HBV replication, and focused our study here on HGS (HRS, hepatocyte growth factor-regulated tyrosine kinase substrate) in the ESCRT-0 complex. Aberrant levels of HGS suppressed HBV transcription, replication and virion secretion. Hydrodynamic delivery of HGS in a mouse model significantly suppressed viral replication in the liver and virion secretion in the serum. Surprisingly, overexpression of HGS stimulated the release of HBV naked capsids, irrespective of their viral RNA, DNA, or empty contents. Mutant core protein (HBc 1-147) containing no arginine-rich domain (ARD) failed to secrete empty virions with or without HGS. In contrast, empty naked capsids of HBc 1-147 could still be promoted for secretion by HGS. HGS exerted a strong positive effect on the secretion of naked capsids, at the expense of a reduced level of virions. The association between HGS and HBc appears to be ubiquitin-independent. Furthermore, HBc is preferentially co-localized with HGS near the cell periphery, instead of near the punctate endosomes in the cytoplasm. In summary, our work demonstrated the importance of an optimum level of HGS in HBV propagation. In addition to an effect on HBV transcription, HGS can diminish the pool size of intracellular nucleocapsids with ongoing genome maturation, probably in part by promoting the secretion of naked capsids. The secretion routes of HBV virions and naked capsids can be clearly distinguished based on the pleiotropic effect of HGS involved in the ESCRT-0 complex.
转运所需的内体分选复合体(ESCRT)是一种重要的细胞机制,用于对泛素化货物进行分选和运输。众所周知,许多病毒的释放也需要ESCRT。为了研究ESCRT与乙型肝炎病毒(HBV)之间的关系,我们对ESCRT组分进行了siRNA筛选,以考察它们对HBV复制和病毒粒子释放的潜在影响。我们鉴定出了一些HBV复制所需的ESCRT因子,并将研究重点放在了ESCRT-0复合体中的HGS(HRS,肝细胞生长因子调节的酪氨酸激酶底物)上。HGS水平异常会抑制HBV转录、复制和病毒粒子分泌。在小鼠模型中通过流体动力学方式递送HGS可显著抑制肝脏中的病毒复制以及血清中的病毒粒子分泌。令人惊讶的是,HGS的过表达会刺激HBV空衣壳的释放,无论其病毒RNA、DNA或空内容物如何。不含富含精氨酸结构域(ARD)的突变核心蛋白(HBc 1-147)无论有无HGS都无法分泌空病毒粒子。相比之下,HBc 1-147的空衣壳仍可被HGS促进分泌。HGS对空衣壳的分泌具有强烈的正向作用,但代价是病毒粒子水平降低。HGS与HBc之间的关联似乎不依赖泛素。此外,HBc优先与HGS在细胞周边附近共定位,而不是在细胞质中的点状内体附近。总之,我们的工作证明了最佳水平的HGS在HBV传播中的重要性。除了对HBV转录有影响外,HGS可能部分通过促进空衣壳的分泌,减少正在进行基因组成熟的细胞内核衣壳的数量。基于ESCRT-0复合体中HGS的多效性作用,可以清楚地区分HBV病毒粒子和空衣壳的分泌途径。