PDZK1 expression is critical for the brush border membrane localisation, membrane half life and cAMP-mediated regulation of enterocyte Na+/H+ exchanger isoform 3

to crypts.Aquaporins are a family of cell plasma membrane channels; AQP3 transports water, and glycerol and putatively also hydrogen peroxide (H 2 O 2 ).AQP3 is expressed on the basolateral membrane of epithelial cells lining the colon, but its exact role in intestinal function in health and disease are not known.To investigate the epithelial specific role of AQP-3 in intestinal crypt formation, we generated small intestinal and colonic enteroids from wild-type and AQP-3 null mice.AQP-3 deficient enteroids exhibited slowed crypt budding and growth on initial isolation.To measure AQP-3 dependent H 2 O 2 transport, enteriods were virally transfected with a ratiometric fluorescent H 2 O 2 sensitive YFP.Enteroids were immobilized on matrigel coated coverslips in a small volume perfusion chamber and live fluorescence imaging carried out.AQP3 deficient enterocytes exhibited slowed membrane hydrogen peroxide transport at high extracellular (>100mM) concentrations.Enteroids grown with hydrogen peroxide on isolation resulted in a change in enteroid morphology.These data suggest that AQP-3 may play a role in crypt formation in response to injury.