Aquaporin-11
hydrogen peroxide channel activity
Human aquaporin-11 guarantees efficient transport of H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; across the endoplasmic reticulum membrane.
Hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) is an essential second intracellular messenger. To reach its targets in the cytosol, H<sub>2</sub>O<sub>2</sub> must cross a membrane, a feat that requires aquaporins (AQP) endowed with 'peroxiporin' activity (AQP3, AQP8, AQP9). Here, we exploit different organelle-targeted H<sub>2</sub>O<sub>2</sub>-sensitive probes to show that also AQP11 efficiently conduits H<sub>2</sub>O<sub>2</sub>. Unlike other peroxiporins, AQP11 is localized in the endoplasmic reticulum (ER), accumulating partly in mitochondrial-associated ER membranes (MAM). Its downregulation severely perturbs the flux of H<sub>2</sub>O<sub>2</sub> through the ER, but not through the mitochondrial or plasma membranes. These properties make AQP11 a potential regulator of ER redox homeostasis and signaling.