Murine Gammaherpesvirus 68 LANA Acts on Terminal Repeat DNA To Mediate Episome Persistence
Murine Gammaherpesvirus 68 LANA Acts on Terminal Repeat DNA To Mediate Episome Persistence
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DOI：
10.1128/jvi.01656-12
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发表时间：
2012-11-01
影响因子：
5.4
通讯作者：
Kaye, Kenneth M.
中科院分区：
文献类型：
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作者：
Habison, Aline C.;Beauchemin, Chantal;Kaye, Kenneth M.
鼠γ疱疹病毒68（MHV 68）ORF 73（m拉娜）与卡波西肉瘤相关疱疹病毒（KSHV）潜伏相关核抗原（拉娜）具有序列同源性。拉娜作用于KSHV末端重复（TR）元件以介导KSHV附加体维持。mLANA表达的破坏严重降低了MHV 68在小鼠中建立潜伏感染的能力，这与mLANA介导附加体持久性的可能性一致。在这里，我们评估的作用mLANA和MHV68 TR（mTR）元件在附加体持久性。mTR相关DNA在潜伏性MHV 68感染的肿瘤细胞中作为附加体持续存在，表明mTR元件可以作为MHV 68附加体维持的顺式作用元件。在一些情况下，对照载体和mTR相关DNA都整合到MHV 68附加型基因组中。因此，我们还评估了在没有感染的情况下mTR和mLANA的作用。在鼠A20或MEF细胞中，顺式含有mLANA和mTR的DNA作为附加体持续存在。相比之下，在没有mLANA的情况下，mTR DNA从未作为附加体持续存在。当mLANA从其天然启动子表达时，mLANA水平增加，并且附加体维持在较高mLANA水平下更有效。增加的mTR数量赋予更有效的附加体维持，因为含有mLANA和8个mTR元件的DNA在A20细胞中比含有mLANA和2个或4个mTR的DNA更有效地持续存在。与KSHV拉娜相似，m拉娜广泛与有丝分裂染色体相关，但在附加体存在下重新定位于集中的点。因此，mLANA作用于mTR元件以介导MHV 68附加体持久性。
Murine gammaherpesvirus 68 (MHV68) ORF73 (mLANA) has sequence homology to Kaposi's sarcoma-associated herpesvirus (KSHV) latency-associated nuclear antigen (LANA). LANA acts on the KSHV terminal repeat (TR) elements to mediate KSHV episome maintenance. Disruption of mLANA expression severely reduces the ability of MHV68 to establish latent infection in mice, consistent with the possibility that mLANA mediates episome persistence. Here we assess the roles of mLANA and MHV68 TR (mTR) elements in episome persistence. mTR-associated DNA persisted as an episome in latently MHV68-infected tumor cells, demonstrating that the mTR elements can serve as a cis-acting element for MHV68 episome maintenance. In some cases, both control vector and mTR-associated DNAs integrated into MHV68 episomal genomes. Therefore, we also assessed the roles of mTRs as well as mLANA in the absence of infection. DNA containing both mLANA and mTRs in cis persisted as an episome in murine A20 or MEF cells. In contrast, mTR DNA never persisted as an episome in the absence of mLANA. mLANA levels were increased when mLANA was expressed from its native promoters, and episome maintenance was more efficient with higher mLANA levels. Increased numbers of mTRs conferred more efficient episome maintenance, since DNA containing mLANA and eight mTR elements persisted more efficiently in A20 cells than did DNA with mLANA and two or four mTRs. Similar to KSHV LANA, mLANA broadly associated with mitotic chromosomes but relocalized to concentrated dots in the presence of episomes. Therefore, mLANA acts on mTR elements to mediate MHV68 episome persistence.