1
|
Qiu Z, Jiang T, Li Y, Wang W, Yang B. Aquaporins in Urinary System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1398:155-177. [PMID: 36717493 DOI: 10.1007/978-981-19-7415-1_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
There are at least eight aquaporins (AQPs) expressed in the kidney. Including AQP1 expressed in proximal tubules, thin descending limb of Henle and vasa recta; AQP2, AQP3, AQP4, AQP5, and AQP6 expressed in collecting ducts; AQP7 expressed in proximal tubules; AQP8 expressed in proximal tubules and collecting ducts; and AQP11 expressed in the endoplasmic reticulum of proximal tubular epithelial cells. Over years, researchers have constructed different AQP knockout mice and explored the effect of AQP knockout on kidney function. Thus, the roles of AQPs in renal physiology are revealed, providing very useful information for addressing fundamental questions about transepithelial water transport and the mechanism of near isoosmolar fluid reabsorption. This chapter introduces the localization and function of AQPs in the kidney and their roles in different kidney diseases to reveal the prospects of AQPs in further basic and clinical studies.
Collapse
Affiliation(s)
- Zhiwei Qiu
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Tao Jiang
- College of Basic Medicine, Beihua University, Jilin, China
| | - Yingjie Li
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Weiling Wang
- Beijing Research Institute of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, P.R. China
| | - Baoxue Yang
- School of Basic Medical Sciences, Peking University, Beijing, China.
| |
Collapse
|
2
|
Xu L, Guo X, Wang W, Li C. Classification and Gene Structure of Aquaporins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1398:1-13. [PMID: 36717483 DOI: 10.1007/978-981-19-7415-1_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Aquaporins (AQPs) are a family of membrane water channels that basically function as regulators of intracellular and intercellular water flow. To date, 13 AQPs, distributed widely in specific cell types in various organs and tissues, have been characterized in humans. A pair of NPA boxes forming a pore is highly conserved among all aquaporins and is also key residues for the classification of AQP superfamily into four groups according to primary sequences. AQPs may also be classified based on their transport properties. So far, chromosome localization and gene structure of 13 human AQPs have been identified, which is definitely helpful for studying phenotypes and potential targets in naturally occurring and synthetic mutations in human or cells.
Collapse
Affiliation(s)
- Long Xu
- Department of Physiology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Xiangdong Guo
- Department of Physiology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Weidong Wang
- Department of Pathophysiology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China.
| | - Chunling Li
- Department of Physiology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China.
| |
Collapse
|
3
|
Insight into the Mammalian Aquaporin Interactome. Int J Mol Sci 2022; 23:ijms23179615. [PMID: 36077012 PMCID: PMC9456110 DOI: 10.3390/ijms23179615] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 08/16/2022] [Accepted: 08/22/2022] [Indexed: 01/07/2023] Open
Abstract
Aquaporins (AQPs) are a family of transmembrane water channels expressed in all living organisms. AQPs facilitate osmotically driven water flux across biological membranes and, in some cases, the movement of small molecules (such as glycerol, urea, CO2, NH3, H2O2). Protein-protein interactions play essential roles in protein regulation and function. This review provides a comprehensive overview of the current knowledge of the AQP interactomes and addresses the molecular basis and functional significance of these protein-protein interactions in health and diseases. Targeting AQP interactomes may offer new therapeutic avenues as targeting individual AQPs remains challenging despite intense efforts.
Collapse
|
4
|
Markou A, Unger L, Abir-Awan M, Saadallah A, Halsey A, Balklava Z, Conner M, Törnroth-Horsefield S, Greenhill SD, Conner A, Bill RM, Salman MM, Kitchen P. Molecular mechanisms governing aquaporin relocalisation. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183853. [PMID: 34973181 PMCID: PMC8825993 DOI: 10.1016/j.bbamem.2021.183853] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 02/07/2023]
Abstract
The aquaporins (AQPs) form a family of integral membrane proteins that facilitate the movement of water across biological membrane by osmosis, as well as facilitating the diffusion of small polar solutes. AQPs have been recognised as drug targets for a variety of disorders associated with disrupted water or solute transport, including brain oedema following stroke or trauma, epilepsy, cancer cell migration and tumour angiogenesis, metabolic disorders, and inflammation. Despite this, drug discovery for AQPs has made little progress due to a lack of reproducible high-throughput assays and difficulties with the druggability of AQP proteins. However, recent studies have suggested that targetting the trafficking of AQP proteins to the plasma membrane is a viable alternative drug target to direct inhibition of the water-conducting pore. Here we review the literature on the trafficking of mammalian AQPs with a view to highlighting potential new drug targets for a variety of conditions associated with disrupted water and solute homeostasis.
Collapse
Affiliation(s)
- Andrea Markou
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Lucas Unger
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Mohammed Abir-Awan
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Ahmed Saadallah
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Andrea Halsey
- MRC Institute of Metabolic Science, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Zita Balklava
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Matthew Conner
- School of Sciences, Research Institute in Healthcare Science, University of Wolverhampton, Wolverhampton WV1 1LY, UK
| | | | - Stuart D Greenhill
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Alex Conner
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Roslyn M Bill
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Mootaz M Salman
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK; Oxford Parkinson's Disease Centre, University of Oxford, South Parks Road, Oxford OX1 3QX, UK.
| | - Philip Kitchen
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK.
| |
Collapse
|
5
|
Ishida H, Vogel HJ, Conner AC, Kitchen P, Bill RM, MacDonald JA. Simultaneous binding of the N- and C-terminal cytoplasmic domains of aquaporin 4 to calmodulin. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183837. [PMID: 34890582 DOI: 10.1016/j.bbamem.2021.183837] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 10/30/2021] [Accepted: 11/30/2021] [Indexed: 10/19/2022]
Abstract
Aquaporin 4 (AQP4) is a water transporting, transmembrane channel protein that has important regulatory roles in maintaining cellular water homeostasis. Several other AQP proteins exhibit calmodulin (CaM)-binding properties, and CaM has recently been implicated in the cell surface localization of AQP4. The objective of the present study was to assess the CaM-binding properties of AQP4 in detail. Inspection of AQP4 revealed two putative CaM-binding domains (CBDs) in the cytoplasmic N- and C-terminal regions, respectively. The Ca2+-dependent CaM-binding properties of AQP4 CBD peptides were assessed using fluorescence spectroscopy, isothermal titration calorimetry, and two-dimensional 1H, 15N-HSQC NMR with 15N-labeled CaM. The N-terminal CBD of AQP4 predominantly interacted with the N-lobe of CaM with a 1:1 binding ratio and a Kd of 3.4 μM. The C-terminal AQP4 peptide interacted with both the C- and N-lobes of CaM (2:1 binding ratio; Kd1: 3.6 μM, Kd2: 113.6 μM, respectively). A recombinant AQP4 protein domain (recAQP4CT, containing the entire cytosolic C-terminal sequence) bound CaM in a 1:1 binding mode with a Kd of 6.1 μM. A ternary bridging complex could be generated with the N- and C-lobes of CaM interacting simultaneously with the N- and C-terminal CBD peptides. These data support a unique adapter protein binding mode for CaM with AQP4.
Collapse
Affiliation(s)
- Hiroaki Ishida
- Biochemistry Research Group, Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Hans J Vogel
- Biochemistry Research Group, Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Alex C Conner
- College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Philip Kitchen
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Roslyn M Bill
- College of Health and Life Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Justin A MacDonald
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4Z6, Canada.
| |
Collapse
|
6
|
Wagner K, Unger L, Salman MM, Kitchen P, Bill RM, Yool AJ. Signaling Mechanisms and Pharmacological Modulators Governing Diverse Aquaporin Functions in Human Health and Disease. Int J Mol Sci 2022; 23:1388. [PMID: 35163313 PMCID: PMC8836214 DOI: 10.3390/ijms23031388] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/18/2022] [Accepted: 01/20/2022] [Indexed: 02/07/2023] Open
Abstract
The aquaporins (AQPs) are a family of small integral membrane proteins that facilitate the bidirectional transport of water across biological membranes in response to osmotic pressure gradients as well as enable the transmembrane diffusion of small neutral solutes (such as urea, glycerol, and hydrogen peroxide) and ions. AQPs are expressed throughout the human body. Here, we review their key roles in fluid homeostasis, glandular secretions, signal transduction and sensation, barrier function, immunity and inflammation, cell migration, and angiogenesis. Evidence from a wide variety of studies now supports a view of the functions of AQPs being much more complex than simply mediating the passive flow of water across biological membranes. The discovery and development of small-molecule AQP inhibitors for research use and therapeutic development will lead to new insights into the basic biology of and novel treatments for the wide range of AQP-associated disorders.
Collapse
Affiliation(s)
- Kim Wagner
- School of Biomedicine, University of Adelaide, Adelaide, SA 5005, Australia;
| | - Lucas Unger
- College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK; (L.U.); (P.K.)
| | - Mootaz M. Salman
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK;
- Oxford Parkinson’s Disease Centre, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
| | - Philip Kitchen
- College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK; (L.U.); (P.K.)
| | - Roslyn M. Bill
- College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK; (L.U.); (P.K.)
| | - Andrea J. Yool
- School of Biomedicine, University of Adelaide, Adelaide, SA 5005, Australia;
| |
Collapse
|
7
|
Kitchen P, Salman MM, Halsey AM, Clarke-Bland C, MacDonald JA, Ishida H, Vogel HJ, Almutiri S, Logan A, Kreida S, Al-Jubair T, Winkel Missel J, Gourdon P, Törnroth-Horsefield S, Conner MT, Ahmed Z, Conner AC, Bill RM. Targeting Aquaporin-4 Subcellular Localization to Treat Central Nervous System Edema. Cell 2020; 181:784-799.e19. [PMID: 32413299 PMCID: PMC7242911 DOI: 10.1016/j.cell.2020.03.037] [Citation(s) in RCA: 260] [Impact Index Per Article: 65.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 01/09/2020] [Accepted: 03/17/2020] [Indexed: 01/07/2023]
Abstract
Swelling of the brain or spinal cord (CNS edema) affects millions of people every year. All potential pharmacological interventions have failed in clinical trials, meaning that symptom management is the only treatment option. The water channel protein aquaporin-4 (AQP4) is expressed in astrocytes and mediates water flux across the blood-brain and blood-spinal cord barriers. Here we show that AQP4 cell-surface abundance increases in response to hypoxia-induced cell swelling in a calmodulin-dependent manner. Calmodulin directly binds the AQP4 carboxyl terminus, causing a specific conformational change and driving AQP4 cell-surface localization. Inhibition of calmodulin in a rat spinal cord injury model with the licensed drug trifluoperazine inhibited AQP4 localization to the blood-spinal cord barrier, ablated CNS edema, and led to accelerated functional recovery compared with untreated animals. We propose that targeting the mechanism of calmodulin-mediated cell-surface localization of AQP4 is a viable strategy for development of CNS edema therapies.
Collapse
Affiliation(s)
- Philip Kitchen
- School of Life & Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Mootaz M Salman
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pharmacology, College of Pharmacy, University of Mosul, Mosul 41002, Iraq
| | - Andrea M Halsey
- Neuroscience and Ophthalmology, Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Charlotte Clarke-Bland
- School of Life & Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK
| | - Justin A MacDonald
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4Z6, Canada
| | - Hiroaki Ishida
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Hans J Vogel
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4Z6, Canada; Department of Biological Sciences, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Sharif Almutiri
- Neuroscience and Ophthalmology, Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; Department of Clinical Laboratory Science, College of Applied Medical Science, Shaqra University, Shaqra, Saudi Arabia
| | - Ann Logan
- Neuroscience and Ophthalmology, Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Stefan Kreida
- Department of Biochemistry and Structural Biology, Lund University, PO Box 124, 221 00 Lund, Sweden
| | - Tamim Al-Jubair
- Department of Biochemistry and Structural Biology, Lund University, PO Box 124, 221 00 Lund, Sweden
| | - Julie Winkel Missel
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Pontus Gourdon
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; Department of Experimental Medical Science, Lund University, PO Box 118, 221 00 Lund, Sweden
| | | | - Matthew T Conner
- School of Sciences, Research Institute in Healthcare Science, University of Wolverhampton, Wolverhampton WV1 1LY, UK
| | - Zubair Ahmed
- Neuroscience and Ophthalmology, Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
| | - Alex C Conner
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
| | - Roslyn M Bill
- School of Life & Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, UK.
| |
Collapse
|
8
|
Su W, Cao R, Zhang XY, Guan Y. Aquaporins in the kidney: physiology and pathophysiology. Am J Physiol Renal Physiol 2019; 318:F193-F203. [PMID: 31682170 DOI: 10.1152/ajprenal.00304.2019] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The kidney is the central organ involved in maintaining water and sodium balance. In human kidneys, nine aquaporins (AQPs), including AQP1-8 and AQP11, have been found and are differentially expressed along the renal tubules and collecting ducts with distinct and critical roles in the regulation of body water homeostasis and urine concentration. Dysfunction and dysregulation of these AQPs result in various water balance disorders. This review summarizes current understanding of physiological and pathophysiological roles of AQPs in the kidney, with a focus on recent progress on AQP2 regulation by the nuclear receptor transcriptional factors. This review also provides an overview of AQPs as clinical biomarkers and therapeutic targets for renal diseases.
Collapse
Affiliation(s)
- Wen Su
- Department of Pathophysiology, Shenzhen University Health Science Center, Shenzhen University, Shenzhen, China
| | - Rong Cao
- Department of Nephrology, The First Affiliated Hospital of Shenzhen University, Shenzhen, China.,The Second People's Hospital of Shenzhen, Shenzhen, China
| | - Xiao-Yan Zhang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, China
| | - Youfei Guan
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, China
| |
Collapse
|
9
|
Roche JV, Törnroth-Horsefield S. Aquaporin Protein-Protein Interactions. Int J Mol Sci 2017; 18:ijms18112255. [PMID: 29077056 PMCID: PMC5713225 DOI: 10.3390/ijms18112255] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 10/20/2017] [Accepted: 10/23/2017] [Indexed: 12/20/2022] Open
Abstract
Aquaporins are tetrameric membrane-bound channels that facilitate transport of water and other small solutes across cell membranes. In eukaryotes, they are frequently regulated by gating or trafficking, allowing for the cell to control membrane permeability in a specific manner. Protein–protein interactions play crucial roles in both regulatory processes and also mediate alternative functions such as cell adhesion. In this review, we summarize recent knowledge about aquaporin protein–protein interactions; dividing the interactions into three types: (1) interactions between aquaporin tetramers; (2) interactions between aquaporin monomers within a tetramer (hetero-tetramerization); and (3) transient interactions with regulatory proteins. We particularly focus on the structural aspects of the interactions, discussing the small differences within a conserved overall fold that allow for aquaporins to be differentially regulated in an organism-, tissue- and trigger-specific manner. A deep knowledge about these differences is needed to fully understand aquaporin function and regulation in many physiological processes, and may enable design of compounds targeting specific aquaporins for treatment of human disease.
Collapse
Affiliation(s)
- Jennifer Virginia Roche
- Department of Biochemistry and Structural Biology, Center for Molecular Protein Science, Lund University, Box 124, 221 00 Lund, Sweden.
| | - Susanna Törnroth-Horsefield
- Department of Biochemistry and Structural Biology, Center for Molecular Protein Science, Lund University, Box 124, 221 00 Lund, Sweden.
| |
Collapse
|
10
|
Abstract
Aquaporins (AQPs ) are a family of membrane water channels that basically function as regulators of intracellular and intercellular water flow. To date, thirteen AQPs , which are distributed widely in specific cell types in various organs and tissues, have been characterized in humans. Four AQP monomers, each of which consists of six membrane-spanning alpha-helices that have a central water-transporting pore, assemble to form tetramers, forming the functional units in the membrane. AQP facilitates osmotic water transport across plasma membranes and thus transcellular fluid movement. The cellular functions of aquaporins are regulated by posttranslational modifications , e.g. phosphorylation, ubiquitination, glycosylation, subcellular distribution, degradation, and protein interactions. Insight into the molecular mechanisms responsible for regulated aquaporin trafficking and synthesis is proving to be fundamental for development of novel therapeutic targets or reliable diagnostic and prognostic biomarkers.
Collapse
Affiliation(s)
- Chunling Li
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, 74# Zhongshan Er Road, Guangzhou, 510080, China
| | - Weidong Wang
- Institute of Hypertension, Zhongshan School of Medicine, Sun Yat-sen University, 74# Zhongshan Er Road, Guangzhou, 510080, China.
| |
Collapse
|
11
|
Li Y, Wang W, Jiang T, Yang B. Aquaporins in Urinary System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 969:131-148. [PMID: 28258571 DOI: 10.1007/978-94-024-1057-0_9] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Several aquaporin (AQP )-type water channels are expressed in kidney: AQP1 in the proximal tubule, thin descending limb of Henle, and vasa recta; AQP2 -6 in the collecting duct; AQP7 in the proximal tubule; AQP8 in the proximal tubule and collecting duct; and AQP11 in the endoplasmic reticulum of proximal tubule cells. AQP2 is the vasopressin-regulated water channel that is important in hereditary and acquired diseases affecting urine-concentrating ability. The roles of AQPs in renal physiology and transepithelial water transport have been determined using AQP knockout mouse models. This chapter describes renal physiologic insights revealed by phenotypic analysis of AQP knockout mice and the prospects for further basic and clinical studies.
Collapse
Affiliation(s)
- Yingjie Li
- Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China
| | - Weiling Wang
- State Key Laboratory of Natural and Biomimetic Drugs, and Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China
| | - Tao Jiang
- Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China
| | - Baoxue Yang
- Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China.
- State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100191, China.
- Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Peking University, Beijing, 100191, China.
| |
Collapse
|
12
|
Sjöhamn J, Båth P, Neutze R, Hedfalk K. Applying bimolecular fluorescence complementation to screen and purify aquaporin protein:protein complexes. Protein Sci 2016; 25:2196-2208. [PMID: 27643892 PMCID: PMC5119558 DOI: 10.1002/pro.3046] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/14/2016] [Accepted: 09/14/2016] [Indexed: 12/22/2022]
Abstract
Protein:protein interactions play key functional roles in the molecular machinery of the cell. A major challenge for structural biology is to gain high‐resolution structural insight into how membrane protein function is regulated by protein:protein interactions. To this end we present a method to express, detect, and purify stable membrane protein complexes that are suitable for further structural characterization. Our approach utilizes bimolecular fluorescence complementation (BiFC), whereby each protein of an interaction pair is fused to nonfluorescent fragments of yellow fluorescent protein (YFP) that combine and mature as the complex is formed. YFP thus facilitates the visualization of protein:protein interactions in vivo, stabilizes the assembled complex, and provides a fluorescent marker during purification. This technique is validated by observing the formation of stable homotetramers of human aquaporin 0 (AQP0). The method's broader applicability is demonstrated by visualizing the interactions of AQP0 and human aquaporin 1 (AQP1) with the cytoplasmic regulatory protein calmodulin (CaM). The dependence of the AQP0‐CaM complex on the AQP0 C‐terminus is also demonstrated since the C‐terminal truncated construct provides a negative control. This screening approach may therefore facilitate the production and purification of membrane protein:protein complexes for later structural studies by X‐ray crystallography or single particle electron microscopy.
Collapse
Affiliation(s)
- Jennie Sjöhamn
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, SE-405 30, Sweden
| | - Petra Båth
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, SE-405 30, Sweden
| | - Richard Neutze
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, SE-405 30, Sweden
| | - Kristina Hedfalk
- Department of Chemistry and Molecular Biology, University of Gothenburg, Göteborg, SE-405 30, Sweden
| |
Collapse
|
13
|
Fields JB, Németh-Cahalan KL, Freites JA, Vorontsova I, Hall JE, Tobias DJ. Calmodulin Gates Aquaporin 0 Permeability through a Positively Charged Cytoplasmic Loop. J Biol Chem 2016; 292:185-195. [PMID: 27660387 DOI: 10.1074/jbc.m116.743724] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/22/2016] [Indexed: 11/06/2022] Open
Abstract
Aquaporin 0 (AQP0), the major intrinsic protein of the eye lens, plays a vital role in maintaining lens clarity by facilitating the transport of water across lens fiber cell membranes. AQP0 reduces its osmotic water permeability constant (Pf) in response to increases in the external calcium concentration, an effect that is mediated by an interaction with the calcium-binding messenger protein, calmodulin (CaM), and phosphorylation of the CaM-binding site abolishes calcium sensitivity. Despite recent structural characterization of the AQP0-CaM complex, the mechanism by which CaM modulates AQP0 remains poorly understood. By combining atomistic molecular dynamics simulations and oocyte permeability assays, we conclude that serine phosphorylation of AQP0 does not inhibit CaM binding to the whole AQP0 protein. Instead, AQP0 phosphorylation alters calcium sensitivity by modifying the AQP0-CaM interaction interface, particularly at an arginine-rich loop that connects the fourth and fifth transmembrane helices. This previously unexplored loop, which sits outside of the canonical CaM-binding site on the AQP0 cytosolic face, mechanically couples CaM to the pore-gating residues of the second constriction site. We show that this allosteric loop is vital for CaM regulation of the channels, facilitating cooperativity between adjacent subunits and regulating factors such as serine phosphorylation. Similar allosteric interactions may also mediate CaM modulation of the properties of other CaM-regulated proteins.
Collapse
Affiliation(s)
- James B Fields
- From the Department of Chemistry, University of California, Irvine, California 92697-2025 and
| | - Karin L Németh-Cahalan
- the Department of Physiology and Biophysics, University of California, Irvine, California 92697-1450
| | - J Alfredo Freites
- From the Department of Chemistry, University of California, Irvine, California 92697-2025 and
| | - Irene Vorontsova
- the Department of Physiology and Biophysics, University of California, Irvine, California 92697-1450
| | - James E Hall
- the Department of Physiology and Biophysics, University of California, Irvine, California 92697-1450
| | - Douglas J Tobias
- From the Department of Chemistry, University of California, Irvine, California 92697-2025 and
| |
Collapse
|
14
|
Jang SY, Lee ES, Ohn YH, Park TK. Expression of Aquaporin-6 in Rat Retinal Ganglion Cells. Cell Mol Neurobiol 2015; 36:965-970. [DOI: 10.1007/s10571-015-0283-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 10/03/2015] [Indexed: 11/24/2022]
|
15
|
Kitchen P, Day RE, Taylor LHJ, Salman MM, Bill RM, Conner MT, Conner AC. Identification and Molecular Mechanisms of the Rapid Tonicity-induced Relocalization of the Aquaporin 4 Channel. J Biol Chem 2015; 290:16873-81. [PMID: 26013827 PMCID: PMC4505433 DOI: 10.1074/jbc.m115.646034] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Indexed: 11/06/2022] Open
Abstract
The aquaporin family of integral membrane proteins is composed of channels that mediate cellular water flow. Aquaporin 4 (AQP4) is highly expressed in the glial cells of the central nervous system and facilitates the osmotically driven pathological brain swelling associated with stroke and traumatic brain injury. Here we show that AQP4 cell surface expression can be rapidly and reversibly regulated in response to changes of tonicity in primary cortical rat astrocytes and in transfected HEK293 cells. The translocation mechanism involves PKA activation, influx of extracellular calcium, and activation of calmodulin. We identify five putative PKA phosphorylation sites and use site-directed mutagenesis to show that only phosphorylation at one of these sites, serine 276, is necessary for the translocation response. We discuss our findings in the context of the identification of new therapeutic approaches to treating brain edema.
Collapse
Affiliation(s)
- Philip Kitchen
- From the Molecular Organisation and Assembly in Cells Doctoral Training Centre, University of Warwick, Coventry CV4 7AL
| | - Rebecca E Day
- the Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield S1 1WB
| | - Luke H J Taylor
- From the Molecular Organisation and Assembly in Cells Doctoral Training Centre, University of Warwick, Coventry CV4 7AL
| | - Mootaz M Salman
- the Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield S1 1WB
| | - Roslyn M Bill
- the School of Life & Health Sciences and Aston Research Centre for Healthy Ageing, Aston University, Aston Triangle, Birmingham B4 7ET, and
| | - Matthew T Conner
- the Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield S1 1WB,
| | - Alex C Conner
- the School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| |
Collapse
|
16
|
Hellstrand E, Kukora S, Shuman CF, Steenbergen S, Thulin E, Kohli A, Krouse B, Linse S, Åkerfeldt KS. Förster resonance energy transfer studies of calmodulin produced by native protein ligation reveal inter-domain electrostatic repulsion. FEBS J 2013; 280:2675-87. [DOI: 10.1111/febs.12269] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 03/11/2013] [Accepted: 03/26/2013] [Indexed: 12/15/2022]
Affiliation(s)
- Erik Hellstrand
- Biophysical Chemistry, Chemical Centre; Lund University; Sweden
| | | | | | | | - Eva Thulin
- Biochemistry and Structural Biology, Chemical Centre; Lund University; Sweden
| | - Anita Kohli
- Department of Chemistry; Haverford College; PA; USA
| | - Beth Krouse
- Department of Chemistry; Haverford College; PA; USA
| | - Sara Linse
- Biochemistry and Structural Biology, Chemical Centre; Lund University; Sweden
| | | |
Collapse
|
17
|
Conner AC, Bill RM, Conner MT. An emerging consensus on aquaporin translocation as a regulatory mechanism. Mol Membr Biol 2012; 30:1-12. [DOI: 10.3109/09687688.2012.743194] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
18
|
Vasiljevic A, Champier J, Figarella-Branger D, Wierinckx A, Jouvet A, Fèvre-Montange M. Molecular characterization of central neurocytomas: Potential markers for tumor typing and progression. Neuropathology 2012; 33:149-61. [DOI: 10.1111/j.1440-1789.2012.01338.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|
19
|
Amado EM, Freire CA, Grassi MT, Souza MM. Lead hampers gill cell volume regulation in marine crabs: stronger effect in a weak osmoregulator than in an osmoconformer. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2012; 106-107:95-103. [PMID: 22115908 DOI: 10.1016/j.aquatox.2011.10.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 10/14/2011] [Accepted: 10/23/2011] [Indexed: 05/31/2023]
Abstract
Hepatus pudibundus is a strictly marine osmoconformer crab, while Callinectes ornatus inhabits estuarine areas, behaving as a weak hyper-osmoregulator in diluted seawater. Osmoconformers are expected to have higher capacity for cell volume regulation, but gill cells of a regulator are expected to display ion transporters to a higher degree. The influence of lead nitrate (10 μM) on the ability of isolated gill cells from both species to volume regulate under isosmotic and hyposmotic conditions were here evaluated. Without lead, under a 25% hyposmotic shock, the gill cells of both species were quite capable of cell volume maintenance. Cells of C. ornatus, however, had a little swelling (5%) during the hyposmotic shock of greater intensity (50%), while cells of H. pudibundus were still capable of volume regulation. In the presence of lead, even under isosmoticity, the gill cells of both species showed about 10% volume reduction, indicating that lead promotes the loss of water by the cells. When lead was associated with 25% and 50% hyposmotic shock, C. ornatus cells lost more volume (15%), when compared to isosmotic conditions, while H. pudibundus cells showed volume regulation. We then analyzed the possible ways of action of lead on the mechanisms of cell volume regulation in the two species. Verapamil (100 μM) was used to inhibit Ca²⁺ channels, ouabain (100 μM) to inhibit Na⁺/K⁺-ATPase, and HgCl₂ (100 μM) to inhibit aquaporins. Our results suggest that: (1) Ca²⁺ channels are candidates for lead entry into gill cells of H. pudibundus and C. ornatus, being the target of lead action in these cells; (2) aquaporins are much more relevant for water flux in H. pudibundus; and (3) the Na⁺/K⁺-ATPase is much more relevant for volume regulation in C. ornatus. Osmoregulators may be more susceptible to metal contamination than osmoconformers, especially in situations of reduced salinity, for two basic reasons: (1) lower capacity of volume regulation and (2) putative higher uptake of Pb²⁺ through ionic pathways that operate in salt absorption, such as, for example, the Na⁺/K⁺-ATPase.
Collapse
Affiliation(s)
- Enelise M Amado
- Departamento de Fisiologia, Setor de Ciências Biológicas, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
| | | | | | | |
Collapse
|
20
|
Aquaporin-6 expression in the cochlear sensory epithelium is downregulated by salicylates. J Biomed Biotechnol 2010; 2010:264704. [PMID: 20111742 PMCID: PMC2810475 DOI: 10.1155/2010/264704] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 09/21/2009] [Accepted: 10/22/2009] [Indexed: 11/17/2022] Open
Abstract
We characterize the expression pattern of aquaporin-6 in the mouse inner ear by RT-PCR and immunohistochemistry. Our data show that in the inner ear aquaporin-6 is expressed, in both vestibular and acoustic sensory epithelia, by the supporting cells directly contacting hair cells. In particular, in the Organ of Corti, expression was strongest in Deiters' cells, which provide both a mechanical link between outer hair cells (OHCs) and the Organ of Corti, and an entry point for ion recycle pathways. Since aquaporin-6 is permeable to both water and anions, these results suggest its possible involvement in regulating OHC motility, directly through modulation of water and chloride flow or by changing mechanical compliance in Deiters' cells. In further support of this role, treating mice with salicylates, which impair OHC electromotility, dramatically reduced aquaporin-6 expression in the inner ear epithelia but not in control tissues, suggesting a role for this protein in modulating OHCs' responses.
Collapse
|