The life cycle of HPV is tied to the differentiation status of its host cell, with productive replication, late gene expression and virion production restricted to the uppermost layers of the stratified epithelium. HPV DNA is histone-associated, exhibiting a chromatin structure similar to that of the host chromosome. Although HPV chromatin is subject to histone post-translational modifications, how the viral life cycle is epigenetically regulated is not well understood. SETD2 is a histone methyltransferase that places the trimethyl mark on H3K36 (H3K36me3), a mark of active transcription. Here, we define a role for SETD2 and H3K36me3 in the viral life cycle. We have found that HPV positive cells exhibit increased levels of SETD2, with SETD2 depletion leading to defects in productive viral replication and splicing of late viral RNAs. Reducing H3K36me3 by overexpression of KDM4A, an H3K36me3 demethylase, or an H3.3K36M transgene also blocks productive viral replication, indicating a significant role for this histone modification in facilitating viral processes. H3K36me3 is enriched on the 3’ end of the early region of the high-risk HPV31 genome in a SETD2-dependent manner, suggesting that SETD2 may regulate the viral life cycle through the recruitment of H3K36me3 readers to viral DNA. Intriguingly, we have found that activation of the ATM DNA damage kinase, which is required for productive viral replication, is necessary for the maintenance of H3K36me3 on viral chromatin and for processing of late viral RNAs. Additionally, we have found that the HPV31 E7 protein maintains the increased SETD2 levels in infected cells through an extension of protein half-life. Collectively, our findings highlight the importance of epigenetic modifications in driving the viral life cycle and identify a novel role for E7 as well as the DNA damage response in the regulation of viral processes through epigenetic modifications.

HPV的生命周期与其宿主细胞的分化状态有关，生产性复制，晚期基因表达和病毒体生产仅限于分层上皮的最上层。HPV DNA与组蛋白相关，表现出类似于宿主染色体的染色质结构。尽管HPV染色质易受组蛋白翻译后修饰的影响，但病毒生命周期如何在表观遗传学上得到调控尚不清楚。SETD2是一种组蛋白甲基转移酶，它在H3K36（H3K36me3）上放置了三甲基标记，H3K36me3是活跃转录的标记。在这里，我们定义了SETD2和H3K36me3在病毒生命周期中的作用。我们已经发现，HPV阳性细胞显示出水平的SETD2，SETD2耗竭导致生产性病毒复制和后期病毒RNA剪接中的缺陷。通过过量表达KDM4A，H3K36me3脱甲基酶或H3.3K36M转基因来降低H3K36me3，也可阻断生产性病毒复制，这表明该组蛋白修饰在促进病毒过程中起着重要作用。H3K36me3以SETD2依赖性方式富集在高危HPV31基因组早期区域的3'端，这表明SETD2可能通过将H3K36me3阅读器募集到病毒DNA来调节病毒的生命周期。有趣的是，我们发现激活ATM DNA损伤激酶（生产性病毒复制所必需）对于维持病毒染色质上的H3K36me3和后期病毒RNA的处理是必需的。此外，我们发现HPV31 E7蛋白通过延长蛋白半衰期来维持感染细胞中SETD2水平的升高。总的来说，