Abstract 14736: Aquaporin 1 Modulates H 2 o 2 -mediated Endothelial Inflammaging

Abstract

Background: Aquaporin 1 (AQP1), a key regulator of endothelial cell function, transports hydrogen peroxide (H 2 O 2 ) into the cells. H 2 O 2 -mediated inflammation has been implicated in endothelial dysfunction, yet specific roles of AQP1-mediated signaling pathways underlying age-dependent endothelial dysfunction remains incompletely understood. Methods: In these studies, we dissected AQP1-regulated inflammation modulation of eNOS signaling pathways in human aortic endothelial cells (HAEC) from passages 5 to 15 by exploiting siRNA approaches, live cell fluorescence imaging with genetically-encoded H 2 O 2 biosensor HyPer, biochemical and in vitro endothelial function assays. Results: We discovered that AQP1 expression remarkably increases in senescent HAEC (P.15) in association with significant increased SA-βgal activity compared to young cells (P.5). H 2 O 2 levels were increased in senescent cell cytosol revealed by fluorescence HyPer imaging. We found that senescence-associated increase in AQP1-mediated H 2 O 2 led to enhanced TNF-α, unlike HO-1, transcription (p<0.01). Moreover, immunofluorescence assay documented that AQP1 gene knock-down significantly ameliorated senescence-associated elevation of adhesion molecule ICAM-1. Immunoblot analyses demonstrated that increased AQP1 protein levels in senescent HAEC leads to significant increase in caveolin-1 phosphorylation (2-fold) and decreases in phosphorylation of AMPK (Thr172; 4-fold) and eNOS (Ser1177; 2-fold) compared to young ECs (for each, p<0.05, n>6). We discovered that AQP1 knock-down improved the reduced angiogenesis and wound healing capacity in association with eNOS down-regulation in senescent endothelial cells. Conclusion: These results establish that AQP1 plays a crucial role in the regulation of H 2 O 2 -mediated inflammation-associated endothelial senescence, and AQP1 deletion improves endothelial dysfunction by ameliorating ROS-modulated inflammaging.