Aquaporin-3 mediates hydrogen peroxide uptake to regulate downstream intracellular signaling

Hydrogen peroxide (H₂O₂) produced by cell-surface NADPH Oxidase (Nox) enzymes is emerging as an important signaling molecule for growth, differentiation, and migration processes. However, how cells spatially regulate H₂O₂ to achieve physiological redox signaling over nonspecific oxidative stress pathways is insufficiently understood. Here we report that the water channel Aquaporin-3 (AQP3) can facilitate the uptake of H₂O₂ into mammalian cells and mediate downstream intracellular signaling. Molecular imaging with Peroxy Yellow 1 Methyl-Ester (PY1-ME), a new chemoselective fluorescent indicator for H₂O ₂, directly demonstrates that aquaporin isoforms AQP3 and AQP8, but not AQP1, can promote uptake of H₂O₂ specifically through membranes in mammalian cells. Moreover, we show that intracellular H ₂O₂ accumulation can be modulated up or down based on endogenous AQP3 expression, which in turn can influence downstream cell signaling cascades. Finally, we establish that AQP3 is required for Noxderived H₂O₂ signaling upon growth factor stimulation. Taken together, our findings demonstrate that the downstream intracellular effects of H₂O₂ can be regulated across biological barriers, a discovery that has broad implications for the controlled use of this potentially toxic small molecule for beneficial physiological functions.