Partial correction of the urinary concentrating defect in aquaporin-1 nullmice by adenovirus-mediated gene delivery

The feasibility of water channel gene delivery to kidney tubules and microv essels was evaluated by delivery of an adenovirus encoding aquaporin I (AQP 1-Ad5) to transgenic AQP1 null mice. In wild-type mice, AQP1 is expressed i n kidney proximal tubule, thin descending limb of Henle, and descending vas a recta, where urine osmolality (U-osm) increases from 1000-1500 mOsm (befo re) to 2500-3500 mOsm after 36 hr of water deprivation. U-osm in AQP1 null mice remains nearly fixed at 650-750 mOsm. AQP1-Ad5 (with a CMV promoter) w as generated and purified. Infection of CHO cells gave strong uniform AQP1 expression with plasma membrane localization and eightfold increased water permeability over noninfected cells. AQP1-Ad5 was delivered to 20 to 25-g A QP1 null mice by tail vein infusion (0-10(10) PFU). At 3-7 days, AQP1 prote in expression was strongest in liver (similar to 20 mu g of AQP1 protein pe r liver) and next strongest in kidney, with expression in proximal tubule a pical and basolateral membranes, and renal microvessels. Functional analysi s showed increased water permeability in apical membrane vesicles from prox imal tubule. AQP1 expression was not detected in glomerulus, limb of Henle, or collecting duct. In water-deprived null mice receiving 5 x 10(9) PFU of AQP1-Ad5, U-osm increased by up to 510 mOsm (mean increase, 225 +/- 24 mOs m; n = 33 mice). Whereas the control mil mice became lethargic and lost 34. 2 +/- 0.6% body weight, the virus-treated mice remained relatively active a nd lost 32.3 +/- 0.7% body weight. Viral DNA and AQP1 transcript were detec ted in kidney and liver of null mice up to 17 weeks after virus infusion; p artial correction of the urinary concentrating defect persisted for 3-5 wee ks. These results demonstrate partial functional correction of a urinary co ncentrating defect by adenoviral delivery of the AQP1 gene.