Isoform-specific Regulation of the Coxsackie and Adenovirus Receptor in Polarized Epithelia

 描述(申请人提供)：腺病毒是一种常见的人类病原体，最早于1953年从扁桃体中发现。在过去的60年里，腺病毒研究在病毒性肺炎的发病机制、疫苗接种以及分子病毒学和细胞生物学的基本方面取得了令人印象深刻的知识。然而，腺病毒仍然是一个重大的民用和军事威胁，因为目前还没有对腺病毒感染的特殊治疗方法。腺病毒也具有临床意义，因为它是人类基因治疗临床试验中最常见的病毒载体。因此，增强腺病毒感染的新技术将提高这些创新疗法的治疗指数。大多数腺病毒和B组柯萨奇病毒共享一个共同的受体：柯萨奇病毒和腺病毒受体(CAR)。一个主要悬而未决的问题是，这些致病病毒是如何从暴露在空气中的肺上皮表面开始感染的。我们的研究小组最近发现，CAR的两种跨膜亚型中的一种(CAREx8)可以定位于暴露在空气中的根尖上皮表面。此外，我们还发现了一种细胞支架蛋白，即具有倒向结构域结构的膜相关鸟氨酸激酶1(MAGI-1)，它是细胞CAREx8蛋白表达水平和顶端腺病毒进入的主要负调控因子。了解MAGI-1调节CAREx8的机制可能会导致能够改变上皮对腺病毒感染的敏感性的新的和特异的治疗方法。我们 假设MAGI-1通过将CAREx8标记为蛋白质监视内质网相关降解(ERAD)途径的底物来下调CAREx8蛋白的表达。我们进一步假设，阻止MAGI-1-CAREx8相互作用的分子将直接影响上皮对腺病毒感染的敏感性。我们的目的是了解MAGI-1介导的CAREx8下调的分子基础，以及特定的细胞通透性多肽是否可以中断这种相互作用，从而减少或增加极化上皮中顶端腺病毒的感染。了解这些分子机制具有重要的临床意义，原因有几个。目前还没有针对柯萨奇病毒或腺病毒感染的特效药；因此，在病毒爆发时阻断病毒结合的能力将是一个重大的治疗进步。另一方面，增强受体顶端表达的能力将与腺病毒介导的肺部疾病(如癌症)的有效基因治疗高度相关。最后，这项工作将使研究生和本科生团队接触到病毒学和医学交界处的重要研究。

 DESCRIPTION (provided by applicant): Adenovirus is a common human pathogen that was first identified from tonsils in 1953. Over the past 6 decades, adenovirus research has yielded impressive knowledge about the pathogenesis of viral pneumonias, vaccination, and basic aspects of molecular virology and cellular biology. However, adenovirus remains a significant civilian and military threat since no specific therapeutic treatment for adenoviral infection exist. Adenovirus is also clinically significant because it is the most common viral vector used in human gene therapy clinical trials. New techniques that enhance adenovirus infection would, thus, improve the therapeutic index of these innovative therapies. Most adenoviruses and group B coxsackieviruses share a common receptor: coxsackievirus and adenovirus receptor (CAR). A major unanswered question has been how these pathogenic viruses initiate infection from the air-exposed lung epithelial surface. Our group has recently discovered that one of the two transmembrane isoforms of CAR (CAREx8) can localize at the air-exposed apical epithelial surface. Moreover, we have found that a cellular scaffolding protein, membrane-associated guanylate kinase with inverted domain structure 1 (MAGI-1), serves as a master negative regulator for cellular CAREx8 protein expression levels and apical adenovirus entry. Understanding the mechanism by which MAGI-1 regulates CAREx8 may lead to novel and specific therapeutics able to alter the susceptibility of an epithelium to adenovirus infection. We hypothesize that MAGI-1 downregulates CAREx8 protein expression by marking CAREx8 as a substrate for the protein-surveillance endoplasmic reticulum associated-degradation (ERAD) pathway. We further hypothesize that molecules that block the MAGI-1-CAREx8 interaction will directly affect the susceptibility of an epithelium to adenovirus infection. We aim to understand the molecular basis of MAGI- 1-mediated CAREx8 down regulation and whether specific cell-permeable peptides can interrupt this interaction to either decrease or increase apical adenovirus infection in polarized epithelia. Understanding these molecular mechanisms is clinically significant for several reasons. Currently there is no specific treatment for coxsackievirus or adenovirus infection; thus, the ability to block virus binding in the face of virl outbreaks would be a significant therapeutic advance. On the other hand, the ability to augment apical expression of the receptor would have high relevance for efficient adenoviral-mediated gene therapy for lung diseases, such as cancer. Finally, this work will expose a team of graduate and undergraduate students to vital research at the interface of virology and medicine.