Intracellular trafficking in innate immunity

先天性和细胞内在免疫反应构成了针对传入病原体的快速防御系统。虽然对生存至关重要，但这些反应的过度活动可能对宿主有害，这些系统的先天遗传错误会导致疾病。为了防止异常诱导，同时保持有效的抗病毒活性，先天免疫必须严格调节。细胞内运输最近已经成为先天免疫信号传导的中心决定因素，包括通过DNA传感、Toll样受体（TLR）活化和自噬的I型干扰素（IFN）诱导。我们已经鉴定了内质网（ER）-高尔基体运输轴的三个组分中的突变，其与属于I型干扰素病（T1 I）谱内的表型相关，即与增强的I型IFN信号传导相关的单基因疾病。目前，只有有限的治疗方案可用于这些毁灭性的疾病，和潜在的分子机制知之甚少。我们的数据表明，COPA，ARF 1和ARFGEF 1是重要的运输信号适配器中央DNA传感，即STING。COPA中的突变导致人类COPA综合征，导致STING在ER-高尔基体中间室（ERGIC）处的积累和慢性STING激活。ARF 1和ARFGEF 1中的致病性突变，引起新的T1 I，促进STING依赖性诱导I型IFN应答。基于这些初步数据，我们的主要研究目标是确定COPA，ARF 1，ARFGEF 1彼此之间以及与STING之间的精确关系，从而为我们了解ER-高尔基体在先天免疫信号转导中的运输提供信息。在我们的第一个工作包中，我们将定义我们在ARF 1和ARFGEF 1中发现的新突变的作用机制，研究它们对STING的定位和激活的影响，以及对下游信号传导和ARF 1/ARFGEF 1依赖性囊泡转运的影响。在第二个目标中，我们将探索STING-COPA-ARF 1-ARFGEF 1的层次结构，进一步剖析STING招募到贩运囊泡的机制，并检查贩运模式。由于STING信号传导不是唯一涉及ER-高尔基体运输的先天免疫途径，因此在第三个目标中，我们将探索COPA-ARF 1-ARFGEF 1轴对TLR活性和自噬的影响。综上所述，我们对孟德尔疾病相关突变的分子和细胞后果的探索将为ER-高尔基体运输对先天免疫的基本调节提供新的见解，并确定参与其中的关键参与者。通过这种方式，我们将更好地了解如何预防致病性慢性免疫活动，从而为罕见的孟德尔疾病和以先天免疫反应失调为特征的更常见疾病状态的未来治疗提供信息。

Innate and cell intrinsic immune responses constitute a rapid defence system against incoming pathogens. While essential to survival, excessive activity of these responses is potentially detrimental to the host, with inborn genetic errors of these systems leading to disease. To prevent aberrant induction, while retaining effective anti-viral activity, innate immunity has to be tightly regulated. Intracellular trafficking has recently emerged as a central determinant of innate immune signalling, including in type I interferon (IFN) induction via DNA sensing, Toll-like receptor (TLR) activation and autophagy. We have identified mutations in three components of the endoplasmic reticulum (ER)-Golgi trafficking axis associated with phenotypes falling within the type I interferonopathy (T1I) spectrum i.e. monogenic diseases associated with enhanced type I IFN signalling. Currently, only limited treatment options are available for these devastating disorders, and the underlying molecular mechanisms are poorly understood. Our data indicate that COPA, ARF1 and ARFGEF1 are important for trafficking of a signalling adaptor central to DNA sensing i.e. STING. Mutations in COPA, causing COPA syndrome in humans, result in accumulation of STING at the ER-Golgi intermediate compartment (ERGIC) and chronic STING activation. Pathogenic mutations in ARF1 and ARFGEF1, causing novel T1Is, promote STING-dependent induction of type I IFN responses. Based on these preliminary data, our primary research aim is to define the precise relationship of COPA, ARF1, ARFGEF1 to each other and to STING, and thereby inform our understanding of ER-Golgi trafficking in innate immune signalling. In our first work package, we will define the mechanism of action of the novel mutations that we have identified in ARF1 and ARFGEF1, examining their impact on the localisation and activation of STING, and the consequences on downstream signalling and ARF1/ARFGEF1-dependent vesicular transport. In the second aim, we will explore the hierarchy of STING-COPA-ARF1-ARFGEF1, further dissect the mechanism(s) of STING recruitment to trafficking vesicles, and examine the mode of trafficking. As STING signalling is not the only innate immune pathway involving ER-Golgi trafficking, in a third aim, we will explore the impact of the COPA-ARF1-ARFGEF1 axis on TLR activity and autophagy. Taken together, our exploration of the molecular and cellular consequences of Mendelian disease-associated mutations will provide novel insights into the fundamental regulation of innate immunity by ER-Golgi trafficking, and characterise the key players involved. In this way, we will better understand how pathogenic, chronic immune activity is prevented, and thus inform the future treatment of both rare Mendelian disorders and more common disease states characterised by dysregulated innate immune responses.