Coxsackievirus and Adenovirus Receptor Interacts with the PDZ3 Domain of MAGI-1

Abstract

<p>A major factor in virus entry into cells is localization and abundance of the primary receptor. The Coxsackievirus and adenovirus receptor (CAR) is the primary receptor for group B coxsackievirus and many serotypes of adenovirus. In most epithelia, a seven exon isoform of CAR (CAREx7) is exclusively localized at the basolateral surface where it behaves as a homophilic adhesion protein and is inaccessible for viral infection. However, in welldifferentiated human airway epithelia, we recently discovered an alternatively spliced, low abundance isoform of CAR (CAREx8) that is apically localized where it may initiate apical viral infection. The two isoforms differ only in the last 26 (CAREx7) or 13 (CAREx8) amino acids of the cytoplasmic domain, which suggests that some intracellular interactions may differ. One such differential interaction involves MAGI-l, an essential PDZ-domain containing protein known to be involved in cell polarization and cancer. We hypothesized that each CAR isoform will interact with at least one of the six MAGI-l PDZ domains. We investigated the specific MAGI-l PDZ domain(s) that interact with each of the CAR isoforms after cloning each individual MAGI-lb PDZ domain (aa 20110, 465-555, 630-730, 840-930, 990-1080, 1140-1230) and inserting into pcDNA3.1. CARMAGI-PDZ interactions were investigated by in vitro translation, immunocytochemistry, coimmunoprecipitation-Western blot analysis, and adenovirus infection. Both isoforms strongly interacted with PDZ3. CAREx8 also interacts with PDZ1. Whereas co-expression of PDZl with CAREx8 did not affect adenovirus infection, co-expression with PDZ3 significantly reduced infection. Understanding the molecular interactions with CAREx8 is clinically significant for several reasons. The ability to block apical binding of the virus in the face of viral 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.</p><p>This presentation occurred at the Wright State University Campus-Wide Celebration of Research, Scholarship and Creative Activities on April 8, 2011</p>