Referenced in: none

Automatically associated channels: Slo1

Title: Plasma Membrane Abundance of Human Aquaporin 5 Is Dynamically Regulated by Multiple Pathways.

Authors: Philip Kitchen, Fredrik Oberg, Jennie Sjöhamn, Kristina Hedfalk, Roslyn M Bill, Alex C Conner, Matthew T Conner, Susanna Törnroth-Horsefield

Journal, date & volume: PLoS ONE, 2015 , 10, e0143027

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/26569106

Abstract
Aquaporin membrane protein channels mediate cellular water flow. Human aquaporin 5 (AQP5) is highly expressed in the respiratory system and secretory glands where it facilitates the osmotically-driven generation of pulmonary secretions, saliva, sweat and tears. Dysfunctional trafficking of AQP5 has been implicated in several human disease states, including Sjögren's syndrome, bronchitis and cystic fibrosis. In order to investigate how the plasma membrane expression levels of AQP5 are regulated, we studied real-time translocation of GFP-tagged AQP5 in HEK293 cells. We show that AQP5 plasma membrane abundance in transfected HEK293 cells is rapidly and reversibly regulated by at least three independent mechanisms involving phosphorylation at Ser156, protein kinase A activity and extracellular tonicity. The crystal structure of a Ser156 phosphomimetic mutant indicates that its involvement in regulating AQP5 membrane abundance is not mediated by a conformational change of the carboxy-terminus. We suggest that together these pathways regulate cellular water flow.