Opposing Effects of cAMP and T259 Phosphorylation on Plasma Membrane Diffusion of the Water Channel Aquaporin-5 in Madin-Darby Canine Kidney Cells

• Published in: PloS one Vol. 10; no. 7; p. e0133324
• Main Authors: Koffman, Jennifer S, Arnspang, Eva C, Marlar, Saw, Nejsum, Lene N
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 28.07.2015; Public Library of Science (PLoS)
• Subjects: Amino Acid Substitution; Animals; Aquaporin 5; Aquaporin 5 - genetics; Aquaporin 5 - metabolism; Aquaporins; Calcium; Calcium (intracellular); Cell membranes; Cyclic AMP; Cyclic AMP - genetics; Cyclic AMP - metabolism; Cyclic AMP-Dependent Protein Kinases - genetics; Cyclic AMP-Dependent Protein Kinases - metabolism; Diffusion; Diffusion coefficient; Diffusion effects; Diffusion rate; Dogs; Interdisciplinary aspects; Kinases; Lateral diffusion; Lipids; Localization; Madin Darby Canine Kidney Cells; Membrane Microdomains - genetics; Membrane Microdomains - metabolism; Membranes; Microscopy; Molecular biology; Mutagenesis; Mutation; Mutation, Missense; Pathways; Phosphorylation; Phosphorylation - physiology; Physiology; Plasma; Plasma membranes; Protein kinase A; Proteins; Quantum dots; Regulatory mechanisms (biology); Rodents; Science; Secretions; Short term; Spectroscopy; Stimuli; Transport; Water flow; Water transport
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0133324

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.