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

艾滋病毒是导致艾滋病的病毒，它仍然是健康不佳和死亡的重要原因，全世界有3700万艾滋病毒携带者，每年约有100万人死亡。尽管在抗病毒治疗方面取得了重大进展，但仍是如此。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。这一知识为在目前的治疗制度中针对关键的病毒过程提供了信息。大多数关于人类遗传学如何影响艾滋病毒复制的筛查研究都是在欧洲人群中进行的，尽管70%以上的感染者和每年近一半的新感染者在非洲。我们合作最近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具有巨大影响。一旦感染，感染者体内的艾滋病毒水平就会达到稳定状态，这一水平是决定免疫系统受到病毒损害的速度的关键因素。这反过来又是一个重要的决定因素，决定了艾滋病毒感染者需要多长时间才能发展为艾滋病。我们的基因组研究表明，基因chd11的高水平表达与病毒的低稳定水平相关。该基因CHD1L产生的蛋白质水平与HIV水平之间的关联强度相当于CCR5的众所周知的突变，CCR5是最常见的传播病毒进入细胞所必需的分子之一，众所周知，这些突变对携带它们的患者提供了显著的保护，使其免受艾滋病毒的感染。因此，CHD1L有可能对艾滋病毒的复制产生巨大的影响。然而，CHD1L如何能够抑制艾滋病毒感染仍不清楚。在这里，我们建议进行研究，以了解CHD1L和HIV之间的相互作用。我们的目标是通过对CHD1L存在和不存在的细胞中不同阶段的标记物的定量，来精确定位CHD1L可能在病毒生命周期中发挥作用的步骤(S)。CHD1L根据细胞中的特定信号解开DNA的包装。在生命周期的两个候选部分中，这一点可能很重要。1.为了表达其蛋白质，HIV将其基因组插入宿主DNA中，这一过程称为整合。CHD1L可能影响这一过程的效率和/或特异性。2.DNA也需要解开才能表达编码的蛋白质；CHD1L同样可能影响这一过程。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，以确定CHD1L在感染和未感染的细胞中结合了什么。通过这种方式，我们将确定CHD1L影响HIV复制的细胞中的蛋白质和途径。我们还将通过改变CHD1L蛋白的关键部分，并监测该蛋白的修饰版本抑制艾滋病毒感染的能力，确定对其限制艾滋病毒感染的能力至关重要的特征。与特定病毒或细胞蛋白的相互作用可以在治疗上被利用来产生治疗艾滋病毒的新方法。我们提议的实验产生的知识对于将我们的初步观察转化为对这种毁灭性病毒的临床有用的治疗是必要的。聚集在一起进行这项工作的专家组处于独特的有利地位，因为他们在这项工作所需技术方面的专业知识以及他们与临床和商业合作伙伴的联系。

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.