Abundance and localization of the Coxsackie-adenovirus receptor

Abstract

<p>One of the most significant changes that occur during development is when epithelial cells transition from a non-polarized to polarized state. This requires the development of a tight junction between cells, separating the apical from basolateral surface. The Coxsackievirus and adenovirus receptor (CAR) is an epithelial junctional transmembrane protein that is involved in cell adhesion and growth. CAR is also important for viral binding to cells and hence its abundance and localization is important for adenovirus infection. We have previously shown that a seven exon isoform of CAR (CAREx7) localizes to the basolateral surface in polarized cells and provides an innate barrier to viral infection. However, we have recently discovered that an alternatively spliced, low-abundance, isoform of CAR (CAREx8) localizes to the apical membrane of polarized primary human airway epithelia. We hypothesize that CAREx8 will be expressed in all epithelial cells and localization will be distinct from CAREx7. We investigated the expression of CAR isoforms in nine cell lines. Through quantitative polymerase chain reaction, confocal microscopy, and Western blot, we found that CAREx8 and CAREx7 are not expressed in Chinese hamster ovary (CHO-Kl) cell line but are expressed in several distinct cell types, including human lung adenocarcinoma epithelia (A549), human colonic carcinoma (CaC02), human submucosal gland (Calu-3), SV40 transformed African Green monkey kidney (COS-7), human embryonic kidney(HEK 293, 293T), Madin Darby canine kidney (MOCK) and normal lung (NuLi-l) cell lines. CAREx7 expression was approximately 10 times more than CAREx8 within all cell types expressing CAR. Whereas both CAR isoforms localize similarly in non-polarized cells (A549, COS-7, 293 and 293T), some CAREx8 was localized to apical surface in polarized cells (CaC02, Calu-3, MOCK, NuLi-l). Elucidation of the mechanism behind CAREx8 localization may have clinically relevant implications such as the prevention of pulmonary viral infections and augmenting adenoviral gene therapy approaches.</p><p>This presentation occurred at the Wright State University Campus-Wide Celebration of Research, Scholarship and Creative Activities on April 16, 2010</p>