title: Opposing Effects of cAMP and T259 Phosphorylation on Plasma Membrane Diffusion of the Water Channel Aquaporin-5 in Madin-Darby Canine Kidney Cells.
abstract: Aquaporin-5 (AQP5) facilitates passive water transport in glandular epithelia in response to secretory stimuli via intracellular pathways involving calcium release, cAMP and protein kinase A (PKA). In epithelial plasma membranes, AQP5 may be acutely regulated to facilitate water transport in response to physiological stimuli by changes in protein modifications, interactions with proteins and lipids, nanoscale membrane domain organization, and turnover rates. Such regulatory mechanisms could potentially be associated with alteration of diffusion behavior, possibly resulting in a change in the plasma membrane diffusion coefficient of AQP5. We aimed to test the short-term regulatory effects of the above pathways, by measuring lateral diffusion of AQP5 and an AQP5 phospho-mutant, T259A, using k-space Image Correlation Spectroscopy of quantum dot- and EGFP-labeled AQP5. Elevated cAMP and PKA inhibition significantly decreased lateral diffusion of AQP5, whereas T259A mutation showed opposing effects; slowing diffusion without stimulation and increasing diffusion to basal levels after cAMP elevation. Thus, lateral diffusion of AQP5 is significantly regulated by cAMP, PKA, and T259 phosphorylation, which could be important for regulating water flow in glandular secretions.
authors.affiliation: Department of Molecular Biology and Genetics and Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Koffman
authors.affiliation: Department of Molecular Biology and Genetics and Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark.
authors.forename: Eva C
authors.initials: EC
authors.lastname: Arnspang
authors.affiliation: Department of Molecular Biology and Genetics and Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark.
authors.forename: Saw
authors.initials: S
authors.lastname: Marlar
authors.affiliation: Department of Molecular Biology and Genetics and Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark.
authors.forename: Lene N
authors.initials: LN
authors.lastname: Nejsum
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D051402:Aquaporin 5 / Q000235:genetics / Q000378:metabolism*; D000242:Cyclic AMP / Q000235:genetics / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D004285:Dogs; D061985:Madin Darby Canine Kidney Cells; D021962:Membrane Microdomains / Q000235:genetics / Q000378:metabolism*; D020125:Mutation, Missense; D010766:Phosphorylation / Q000502:physiology
chemical_list: D051402:Aquaporin 5; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases