Submitted on May 19, 2004
Accepted on September 13, 2004
Adenovirus Stimulates Choline Efflux by Increasing Expression of Organic Cation Transporter-2
Olga L. Miakotina1, Marianna Agassandian1, Lei Shi1, Dwight C. Look1, and Rama K. Mallampalli2*
1 Department of Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, USA
2 Department of Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, USA; Department of Biochemistry, University of Iowa Carver College of Medicine, Iowa City, IA, USA; Department of Veteran's Affairs, Iowa City, IA, USA
* To whom correspondence should be addressed. E-mail: rama-mallampalli{at}uiowa.edu.
We examined the effect of wild-type human adenovirus (Ad5) on choline transport in murine lung epithelia (MLE) and in rodent primary alveolar type II cells. Cells were active in pHsensitive, reversible transport of choline, a process blocked pharmacologically using phenoxybenzamine, an inhibitor of organic cation transporters (OCT). PCR products for the choline transporters, OCT-1 and OCT-2, were detected but only OCT-2 protein was robustly
expressed within MLE and primary alveolar epithelial cells. Ad5 produced a 2-3 fold increase in choline efflux from cells resulting in a significant reduction in intracellular choline content and its major product, phosphatidylcholine. Effects of Ad5 on choline efflux were inhibited using
phenoxybenzamine and choline efflux was attenuated using OCT-2 siRNA. Adenovirus also produced a dose-dependent increase in immunoreactive OCT-2 levels concomitant with
increased cellular OCT-2 steady-state mRNA. These results indicate that adenoviruses can significantly disrupt choline trafficking in lung epithelia by upregulating expression of an alveolar protein involved in organic cation transport.
