Rebecca E Day1, Philip Kitchen2, David S Owen1, Charlotte Bland3, Lindsay Marshall3, Alex C Conner4, Roslyn M Bill5, Matthew T Conner6. 1. Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, UK. 2. Molecular Organisation and Assembly in Cells Doctoral Training Centre, University of Warwick, Coventry CV4 7AL, UK. 3. School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK. 4. School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. Electronic address: a.c.conner@bham.ac.uk. 5. School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK. Electronic address: r.m.bill@aston.ac.uk. 6. Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, UK. Electronic address: M.Conner@shu.ac.uk.
Abstract
BACKGROUND: Emerging evidence supports the view that (AQP) aquaporin water channels are regulators of transcellular water flow. Consistent with their expression in most tissues, AQPs are associated with diverse physiological and pathophysiological processes. SCOPE OF REVIEW: AQP knockout studies suggest that the regulatory role of AQPs, rather than their action as passive channels, is their critical function. Transport through all AQPs occurs by a common passive mechanism, but their regulation and cellular distribution varies significantly depending on cell and tissue type; the role of AQPs in cell volume regulation (CVR) is particularly notable. This review examines the regulatory role of AQPs in transcellular water flow, especially in CVR. We focus on key systems of the human body, encompassing processes as diverse as urine concentration in the kidney to clearance of brain oedema. MAJOR CONCLUSIONS: AQPs are crucial for the regulation of water homeostasis, providing selective pores for the rapid movement of water across diverse cell membranes and playing regulatory roles in CVR. Gating mechanisms have been proposed for human AQPs, but have only been reported for plant and microbial AQPs. Consequently, it is likely that the distribution and abundance of AQPs in a particular membrane is the determinant of membrane water permeability and a regulator of transcellular water flow. GENERAL SIGNIFICANCE: Elucidating the mechanisms that regulate transcellular water flow will improve our understanding of the human body in health and disease. The central role of specific AQPs in regulating water homeostasis will provide routes to a range of novel therapies. This article is part of a Special Issue entitled Aquaporins.
BACKGROUND: Emerging evidence supports the view that (AQP) aquaporin water channels are regulators of transcellular water flow. Consistent with their expression in most tissues, AQPs are associated with diverse physiological and pathophysiological processes. SCOPE OF REVIEW: AQP knockout studies suggest that the regulatory role of AQPs, rather than their action as passive channels, is their critical function. Transport through all AQPs occurs by a common passive mechanism, but their regulation and cellular distribution varies significantly depending on cell and tissue type; the role of AQPs in cell volume regulation (CVR) is particularly notable. This review examines the regulatory role of AQPs in transcellular water flow, especially in CVR. We focus on key systems of the human body, encompassing processes as diverse as urine concentration in the kidney to clearance of brain oedema. MAJOR CONCLUSIONS: AQPs are crucial for the regulation of water homeostasis, providing selective pores for the rapid movement of water across diverse cell membranes and playing regulatory roles in CVR. Gating mechanisms have been proposed for human AQPs, but have only been reported for plant and microbial AQPs. Consequently, it is likely that the distribution and abundance of AQPs in a particular membrane is the determinant of membrane water permeability and a regulator of transcellular water flow. GENERAL SIGNIFICANCE: Elucidating the mechanisms that regulate transcellular water flow will improve our understanding of the human body in health and disease. The central role of specific AQPs in regulating water homeostasis will provide routes to a range of novel therapies. This article is part of a Special Issue entitled Aquaporins.
Authors: Stefan Schob; Alexey Surov; Andreas Wienke; Hans Jonas Meyer; Rolf Peter Spielmann; Eckhard Fiedler Journal: Mol Imaging Biol Date: 2017-02 Impact factor: 3.488
Authors: Paolo E Palacio-Mancheno; Thomas W Evashwick-Rogler; Damien M Laudier; Devina Purmessur; James C Iatridis Journal: J Orthop Res Date: 2017-09-20 Impact factor: 3.494