OVEREXPRESSION OF THE NA-ATPASE ALPHA(1) SUBUNIT INCREASES NA+,K+-ATPASE FUNCTION IN A549 CELLS(,K+)

We hypothesized that viral mediated transfer of Na+,K+-ATPase subunit genes to alveolar epithelial cells to overexpress Na+,K+-ATPase could increase Na+,K+-ATPase function. We produced replication-deficient hum an type 5 adenoviruses that contained cytomegalovirus (CMV)-driven cDN As for the rat alpha(1) and beta(1) subunits of Na+,K+-ATPase (AdMRCMV alpha(1) and AdMRCMV beta(1), respectively). These viruses were used to transduce human adenocarcinoma cells (A549) in culture. Na+,K+-ATPa se function was increased by 2.5-fold in the AdMRCMV alpha(1)-infected cells. Sham and AdMRCMV beta(1)-infected cells, and cells infected by a CMV-driven beta-galactosidase-expressing adenovirus, had no increas es in Na+,K+-ATPase activity. A549 cells infected with multiplicities of infection of 10-200 of AdMRCMV alpha(1) demonstrated expression of a rat alpha(1) mRNA and increased alpha(1) protein; no change in beta( 1) message or protein was noted. Ouabain sensitivity was measured in A 549 cells following infection with AdMRCMV alpha(1). In contrast to co ntrols, AdMRCMV alpha(1)-infected cells demonstrated two IC(50)s. The first was similar to the IC(50)s of the controls; the second IC50 was 2 logs greater than the first, consistent with the presence of both th e rat and human alpha(1) isozymes. These results demonstrate for the f irst time that adenoviruses can be used to augment Na+,K+-ATPase funct ion.