Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale School of Medicine, New Haven, Connecticut, USA.
Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Yale School of Medicine, New Haven, Connecticut, USA
J Virol. 2018 Jun 13;92(13). doi: 10.1128/JVI.00220-18. Print 2018 Jul 1.
Kaposi's sarcoma-associated herpesvirus (KSHV), like other herpesviruses, replicates within the nuclei of its human cell host and hijacks host machinery for expression of its genes. The activities that culminate in viral DNA synthesis and assembly of viral proteins into capsids physically concentrate in nuclear areas termed viral replication compartments. We sought to better understand the spatiotemporal regulation of viral RNAs during the KSHV lytic phase by examining and quantifying the subcellular localization of select viral transcripts. We found that viral mRNAs, as expected, localized to the cytoplasm throughout the lytic phase. However, dependent on active viral DNA replication, viral transcripts also accumulated in the nucleus, often in foci in and around replication compartments, independent of the host shutoff effect. Our data point to involvement of the viral long noncoding polyadenylated nuclear (PAN) RNA in the localization of an early, intronless viral mRNA encoding ORF59-58 to nuclear foci that are associated with replication compartments. Late in the lytic phase, mRNAs from Kaposi's sarcoma-associated herpesvirus accumulate in the host cell nucleus near viral replication compartments, centers of viral DNA synthesis and virion production. This work contributes spatiotemporal data on herpesviral mRNAs within the lytic host cell and suggests a mechanism for viral RNA accumulation. Our findings indicate that the mechanism is independent of the host shutoff effect and splicing but dependent on active viral DNA synthesis and in part on the viral noncoding RNA, PAN RNA. PAN RNA is essential for the viral life cycle, and its contribution to the nuclear accumulation of viral messages may facilitate propagation of the virus.
卡波济肉瘤相关疱疹病毒（KSHV）与其他疱疹病毒一样，在其人类宿主细胞的核内复制，并劫持宿主机制来表达其基因。最终导致病毒 DNA 合成和病毒蛋白组装成衣壳的活动集中在称为病毒复制区的核区。我们通过检查和量化选定病毒转录本的亚细胞定位，试图更好地了解 KSHV 裂解期病毒 RNA 的时空调节。我们发现，正如预期的那样，病毒 mRNA 在整个裂解期都定位于细胞质中。然而，依赖于活跃的病毒 DNA 复制，病毒转录本也在核内积累，通常在复制区内外的焦点中，而不依赖于宿主关闭效应。我们的数据表明，病毒长非编码多聚腺苷酸化核 (PAN) RNA 参与了早期无内含子病毒 mRNA 的定位，该 mRNA 编码 ORF59-58，定位于与复制区相关的核焦点。在裂解期后期，KSHV 的 mRNA 积累在宿主细胞核内靠近病毒复制区，这是病毒 DNA 合成和病毒粒子产生的中心。这项工作为裂解宿主细胞内疱疹病毒 mRNA 提供了时空数据，并提出了一种病毒 RNA 积累的机制。我们的发现表明，该机制独立于宿主关闭效应和剪接，但依赖于活跃的病毒 DNA 合成，部分依赖于病毒非编码 RNA，即 PAN RNA。PAN RNA 对病毒生命周期至关重要，其对病毒信息核积累的贡献可能有助于病毒的传播。
