Dissecting the mechanism of action of CHD1L, a novel regulator of HIV-1 infection

导致艾滋病的病毒艾滋病毒仍然是健康不良和死亡的一个重要原因，全世界有3 700万人感染该病毒，每年造成约100万人死亡。尽管在抗病毒治疗方面取得了重大进展。病毒与受感染的人类细胞相互作用，其中一些相互作用涉及宿主防御分子，这些分子严重影响病毒完成其生命周期的能力。这一知识为当前治疗方案中关键病毒过程的靶向提供了信息。大多数关于人类基因如何影响艾滋病毒复制的筛选研究都是在欧洲人群中进行的，尽管每年有超过70%的感染者和近一半的新感染者在非洲。我们最近合作进行的一项研究揭示了一种新的基因，它对非洲血统患者的艾滋病毒复制有巨大的影响。感染后，感染者体内的HIV水平达到稳定状态，这一水平是决定免疫系统被病毒破坏速度的关键因素。这反过来又成为艾滋病毒感染者发展为艾滋病所需时间长短的重要决定因素。我们的基因组研究表明，chd11基因的高水平表达与较低的病毒稳态水平相关。这种基因CHD1L产生的蛋白质水平与HIV水平之间的关联强度相当于CCR5中描述良好的突变，CCR5是大多数常见传播病毒进入细胞所必需的分子之一，并且已知这些突变对携带它们的患者具有显著的保护作用。因此，CHD1L具有对HIV复制产生巨大影响的潜力。然而，目前尚不清楚CHD1L是如何抑制HIV感染的。在这里，我们提出研究了解CHD1L和HIV之间的相互作用。我们的目标是通过量化具有和不具有CHD1L的细胞中不同阶段的标记物，确定病毒生命周期中CHD1L可能发挥作用的步骤。CHD1L对细胞中的特定信号作出反应，解开DNA的包装。在生命周期的两个候选部分中，这可能很重要。1. 为了表达其蛋白质，HIV将其基因组插入宿主DNA中，这一过程被称为整合。CHD1L可影响该过程的效率和/或特异性。2. DNA也需要解绕，编码的蛋白质才能表达；CHD1L也会影响这个过程。我们还将通过使用高度敏感的技术来确定CHD1L是否与任何特定的HIV蛋白结合，以观察CHD1L在感染和未感染细胞中的结合。通过这种方式，我们将确定细胞中通过CHD1L影响HIV复制的蛋白质和途径。我们还将确定CHD1L蛋白的特征，这些特征对其限制HIV感染的能力至关重要，方法是改变蛋白质的关键部分，并监测修饰后的蛋白质抑制HIV感染的能力。与特定病毒或细胞蛋白的相互作用可以用于治疗，以产生新的治疗HIV的方法。我们提出的实验所产生的知识对于将我们的初步观察转化为对这种破坏性病毒的临床有用治疗是必要的。为开展这项工作而召集的专家组处于独特的有利地位，因为他们在这项工作所需的技术方面具有专门知识，并与临床和商业伙伴有联系。

HIV, the virus that causes AIDS, remains an important cause of ill health and mortality, with 37 million people living with the virus worldwide and annually being responsible for around 1 million deaths. This is despite significant progress in antiviral treatments. The virus interacts with infected human cells, and some of these interactions involve host defence molecules that critically affect the ability of the virus to complete its life cycle. This knowledge has informed the targeting of crucial viral processes in current treatment regimes. Most screening studies on how human genetics affect HIV replication have been conducted on European populations, despite more than 70 % of infected individuals and nearly half of new infections each year being in Africa. A recent study conducted by our collaboration has revealed a novel gene which has an enormous impact on HIV replication in patients of African ancestry. Upon infection, the level of the HIV in the body of the infected patient reaches a steady state and this level is a key factor in determining how quickly the immune system is compromised by the virus. This, in turn, is an important determinant of how long an HIV-infected individual takes to progress to AIDS. Our genomic study shows that a higher level of expression of a gene, chd1l, is associated with a lower steady state level of virus. The strength of the association between the level of protein produced by this gene CHD1L and the HIV level is equivalent to that of well described mutations in CCR5, one of the molecules necessary for most commonly transmitted viruses to gain entry into a cell, and these mutations are known to confer significant protection from HIV in patients harbouring them. Thus CHD1L has the potential to have an enormous impact on HIV replication.It remains unclear, however, how CHD1L is able to inhibit HIV infection. Here we propose research to understand the interaction between CHD1L and HIV. We aim to pinpoint the step(s) in the virus life cycle at which CHD1L may be exerting an effect, through quantifying the markers of the different stages in cells with and without CHD1L. CHD1L unwinds the packaging of DNA in response to specific signals in the cell. There are two candidate parts of the life cycle where this could be important. 1. In order to express its proteins, HIV inserts its genome into the host DNA in a process called integration. CHD1L could affect the efficiency and/or specificity of this process. 2. DNA also needs to be unwound for the encoded proteins to be expressed; again CHD1L could affect this process. We will also determine whether CHD1L binds to any specific HIV proteins by using highly sensitive techniques to see what CHD1L is bound to in infected and uninfected cells. In this way, we will identify the proteins and pathways in the cell through which CHD1L affects HIV replication. We will also identify features of the CHD1L protein that are essential for its ability to limit HIV infection by making changes to key parts of the protein and monitoring the ability of modified versions of the protein to inhibit HIV infection. Interactions with specific viral or cellular proteins could be exploited therapeutically to generate new treatments for HIV. The knowledge generated by our proposed experiments is necessary to translate our initial observation into clinically useful treatment for this devastating virus. The group of experts assembled to carry out this work are uniquely well-placed position to do this due to their expertise in the technology required for this work and their links to clinical and commercial partners.