Role of epithelial cell intracellular trafficking in the innate immune response to adenovirus infection

摘要 极化上皮的顶端表面构成了宿主和宿主之间的第一个接触点之一。 侵入呼吸道管腔的病原体，如人类腺病毒(HAdv)。在最近 多年来，呼吸道上皮细胞不仅是功能和物理屏障，而且 积极促进先天免疫系统，提供对外部病原体的初步保护。这个 表皮生长因子受体(EGFR)，通常表现为基底侧极性，已成为先天的关键角色。 呼吸道上皮对各种感染性和非感染性有害刺激的免疫力。与之相对的是 典型的配体刺激的EGFR途径，包括HAdV感染(OUR)在内的许多细胞应激 研究)触发与持续的EGFR活动相关的EGFR贩运的替代模式 可降解的内噬菌体。然而，调控这一途径的分子机制仍然知之甚少。 此外，尽管在理解病理和治疗压力方面取得了重大进展，但 在细胞应激的背景下，人们对EGFR的功能知之甚少。我们最近发现， 应激诱导的EGFR信号也参与了HAdV进入细胞所触发的先天免疫反应 如暴露于促炎症细胞因子肿瘤坏死因子-α，在呼吸道上皮细胞。此外，HAdV 编码一种早期的基因产物，通过促进EGFR的降解来抑制这一途径，并且 可能为未来抗病毒疗法的潜在靶点提供新的见解。有趣的是，我们的初选 研究表明，EGFR的应激反应受到上皮细胞极性的严格调控，具有强大的 只有当受体错误定位到顶膜时，才能观察到应激诱导的EGFR反应。在……里面 此外，HAdV通过启动动态的EGFR来参与先天性免疫信号的细胞通路 顶膜重塑与应力诱导的顶膜EGFR信号增强有关。 新描述的EGFR先天免疫系统可能在保护肺部免受 感染人类免疫缺陷病毒，也许还有其他病原体。相反，如果不能遏制这个信令网络，可能会导致 组织损伤，呼吸受损，以及潜在的全身性HAdV感染。我们的研究计划将 识别调节极化上皮细胞动态EGFR膜重构的新机制(AIM 1)，以及应激诱导的EGFR来自内体的先天免疫信号(目标2)；以及分析EGFR先天 原发人感染HAdV后被激活的免疫信号通路 呼吸上皮细胞和顶端EGFR表达增强的新的生理细胞模型(目标3)。 虽然我们的研究将在HAdv的背景下进行，但这一项目的成功完成将具有 对各种呼吸系统疾病的广泛影响需要新的治疗方法。

ABSTRACT The apical surface of polarized epithelium constitutes one of the first points of contact between the host and pathogens such as human adenoviruses (HAdVs) that invade the lumen of the respiratory tract. In recent years, it has become clear that respiratory epithelial cells not only serve as functional and physical barriers, but actively contribute to the innate immune system providing initial protection against external pathogens. The EGF receptor (EGFR), which typically exhibits basolateral polarity, has emerged as a key player in the innate immunity of respiratory epithelium to a variety of infectious and noninfectious noxious stimuli. In contrast to the canonical ligand-stimulated EGFR pathway, a number of cellular stresses including HAdV infection (our studies) trigger an alternative mode of EGFR trafficking associated with sustained EGFR activity in non- degradative endosomes. However, molecular mechanisms regulating this pathway remain poorly understood. In addition, despite significant progress in understanding the pathological and therapeutic stresses that activate it, relatively little is known about EGFR function in the context of cellular stress. We have recently found that stress-induced EGFR signaling is involved in innate immune responses triggered by HAdV cell entry, as well as following exposure to the pro-inflammatory cytokine TNF-α, in respiratory epithelial cells. Moreover, HAdV encodes an early gene product that suppresses this pathway by promoting EGFR degradation, and which could provide new insights to potential targets for future anti-viral therapies. Interestingly, our preliminary studies have revealed that EGFR stress responses were tightly regulated by epithelial cell polarity, with robust stress-induced EGFR responses only observed when receptors were mistargeted to apical membranes. In addition, HAdV co-opted cellular pathways contributing to innate immune signaling by enabling dynamic EGFR membrane remodeling associated with enhanced stress-induced EGFR signaling from apical membranes. The newly described EGFR innate immune system is likely to have a central role in protecting the lung from infection with HAdVs and perhaps other pathogens. Conversely, failure to curb this signaling network may lead to tissue damage, respiratory compromise, and potentially systemic HAdV infections. Our research plan will identify novel mechanisms regulating dynamic EGFR membrane remodeling in polarized epithelial cells (Aim 1), and stress-induced EGFR innate immune signaling from endosomes (Aim 2); and analyze EGFR innate immune signaling pathways that are activated as a consequence of HAdV infection in primary human respiratory epithelial cells and new physiological cells models with enhanced apical EGFR expression (Aim 3). Although our studies will be carried out in the context of HAdVs, successful completion of this project will have a broad impact on a variety of respiratory conditions in need of new therapies.