Expression of Coxsackievirus and Adenovirus Receptor Isoforms in Developing Mouse Bladder Uroepithelium

Abstract

OBJECTIVES Tight junctions are important for uroepithelial paracellular permeability barriers. In the present study, we examined the developmental changes in the expression of coxsackievirus and adenovirus receptor (CAR) isoforms in mouse bladder uroepithelium. METHODS Multiplex reverse transcriptase polymerase chain reaction using CAR isoform-specific primer sets and Western blotting were conducted on gestational day 19 and postnatal days 1, 7, and 55. Subcellular localization of CAR was examined, together with occludin and zonula occludens-1, in neonatal and adult bladder using light microscopy and immunofluorescence microscopy. RESULTS The total CAR and short CAR isoform mRNA were significantly increased from gestational day 19 to birth. Long CAR isoform mRNA was transiently decreased on postnatal day 7 and had recovered during adulthood. On Western blotting, molecular weight 46-kDa CAR was abundant in the mucosa and increased postnatally. In the neonatal, as well as the adult, bladder uroepithelium, CAR immunoreactivity was observed, together with occludin and zonula occludens-1 at the apical tight junctions and basolateral contacts between the adjacent uroepithelial cells. In adult bladder uroepithelium, CAR was increased at the interface between the basal cells and basal lamina. CONCLUSIONS The expression patterns of CAR isoforms changed during the late fetal to adult development of the mouse bladder. CAR at the apical tight junctions and cellular adhesions between the uroepithelial cells and the interfaces between the basal cells and basal lamina might support the paracellular permeability barrier and structural integrity of the uroepithelium in the mouse bladder. The expression of CAR in the uroepithelial cells can be integrated as a part of the strategy for virus-mediated gene therapy in the bladder uroepithelium.