Transcriptional Crosstalk between DUX4-FL and HIV

摘要 根除艾滋病毒的策略旨在从潜伏感染的记忆池中清除残留的艾滋病毒转录 在接受有效的抗逆转录病毒治疗(ART)的HIV感染者(PLWH)中持续存在的CD4+T细胞。 这些细胞含有一种前病毒，当宿主在hiv启动子上连续招募时，病毒就会反弹。 转录延伸因子、病毒TAT蛋白和宿主染色质重构体(这一过程称为TAT- 中介转录)。长期阻断这种残留的艾滋病毒转录，在不同的艾滋病毒潜伏期模型中， 使用Tat的抑制剂，会导致HIV异染色质和RNA聚合酶II的丢失 启动子，同时防止病毒反弹。因此，我们的前提是转录和染色质重塑 可将抑制剂与TAT抑制剂一起用于阻断和锁定功能治疗方法，目的是 减少抗逆转录病毒治疗期间的残余病毒血症，限制病毒反弹。此外，获得新的有洞察力的知识 对这些因子和艾滋病毒转录之间的联系的研究将有助于利用它们作为抗病毒靶标。 我们已经发现，全长异构体的表达与 双同源盒蛋白4(DUX4-FL)在原代血液中的表达与HIV感染DUX4-FL 通过促进残留和TAT介导的艾滋病毒转录，有力地激活艾滋病毒转录活性。 此外，HIV增强了DUX4-FL转录，这表明HIV与DUX4-FL之间存在正转录串扰 和DUX4-FL。DUX4-FL是一种强转录因子，主要在疾病表型中表达，如 面部肩周肌营养不良和癌症，但从未被描述为调节艾滋病毒。在疾病中， DUX4-FL通常调节进化或免疫适应基因的表达，导致毒性和/或 逃避免疫系统。DUX4-FL也被描述为通过招募 组蛋白变体或染色质重构体，促进染色质持久松弛。重要的是，战略以 中和小鼠体内DUX4-FL的过度表达已被证明是安全的，并提供了好处。 为了探索DUX4-FL在HIV转录中的作用，我们建议对DUX4进行鉴定和定量 在相关的艾滋病毒产生型或潜伏型模型中表达的异构体。这将确保我们研究的意义， 因为DUX4-FL预计不会在血液中表达的CD4+T细胞。我们将定义通过哪些机制 DUX4-FL上调HIV转录。我们将研究DUX4-FL直接招募到HIV启动子，其 对表观遗传标记的影响，并发现与DUX4-FL多管齐下的细胞蛋白 方法，包括蛋白质组学、基因组学和基于细胞的方法。 这项研究的首要目标是明确确定DUX4-FL或复杂蛋白是否 对HIV转录调控很重要，长期的目标是利用这些因素来治疗HIV 功能性治愈方法。

Abstract HIV eradication strategies aim to clear residual HIV transcription, from a pool of latently infected memory CD4+ T cells, that persist in people living with HIV (PLWH) treated with an effective antiretroviral therapy (ART). These cells harbor a provirus poised to viral rebound upon a sequential recruitment, at the HIV promoter, of host transcription elongation factors, the viral Tat protein and host chromatin remodelers (a process called Tat- mediated transcription). Long-term block of this residual HIV transcription, in different models of HIV latency, using an inhibitor of Tat, results in an heterochromatinization and a loss of RNA polymerase II at the HIV promoter, along with preventing viral rebound. Thus, our premise is that transcriptional and chromatin remodeling inhibitors along with Tat inhibitors can be used in the block-and-lock functional cure approaches, aimed at reducing residual viremia during ART and limiting viral rebound. Additionally, gaining fresh insightful knowledge on the connections between these factors and HIV transcription will help leverage them as antiviral targets. We have uncovered a direct positive relationship between the expression of the full-length isoform of the double homeobox protein 4 (DUX4-FL) expression and HIV infection in primary blood CD4+T cells. DUX4-FL robustly activates HIV transcriptional activity by promoting both residual and Tat-mediated HIV transcription. Furthermore, HIV enhances DUX4-FL transcription suggesting a positive transcriptional crosstalk between HIV and DUX4-FL. DUX4-FL is a strong transcription factor that is mostly expressed in disease phenotypes, such as facioscapulohumeral muscular dystrophy and cancers, but has never been described to regulate HIV. In disease, DUX4-FL typically regulates expression of evolutionally or immune adaptative genes, resulting in toxicity and/or evasion from the immune system. DUX4-FL has also been described to open compacted chromatin by recruiting histone variants or chromatin remoders promoting long-lasting chromatin relaxation. Importantly, strategies to neutralize the overexpression of DUX4-FL in mice have shown to be safe and provide benefits. To explore the role of DUX4-FL in the context of HIV transcription, we propose to identify and quantify DUX4 isoforms expressed in relevant HIV productive or latent models. This will ensure the significance of our studies, since DUX4-FL is not expected to be expressed in blood CD4+T cells. We will define the mechanism by which DUX4-FL upregulates HIV transcription. We will study the direct DUX4-FL recruitment to the HIV promoter, its impact on epigenetic marks, and uncover cellular proteins complexed with DUX4-FL via a multipronged approach, including proteomics, genomics and cell-based approaches. The overarching goal of this study is to explicitly establish whether DUX4-FL, or complexed proteins, are important for HIV transcriptional regulation, with the longstanding objective of exploiting these factors for HIV functional cure approaches.