1
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Mack AF, Bihlmaier R, Deffner F. Shifting from ependyma to choroid plexus epithelium and the changing expressions of aquaporin-1 and aquaporin-4. J Physiol 2024; 602:3097-3110. [PMID: 37975746 DOI: 10.1113/jp284196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Accepted: 10/30/2023] [Indexed: 11/19/2023] Open
Abstract
The cells of the choroid plexus (CP) epithelium are specialized ependymal cells (ECs) but have distinct properties. The CP cells and ECs form single-cell sheets contiguous to each other at a transitional zone. The CP is underlined by a basal lamina and has barrier properties, whereas the ECs do not. The basal lamina of the CP is continuous with the glia limitans superficialis and, consequently, the CP stroma is continuous with the meninges along entering blood vessels. The CP has previously been reported to express aquaporin-1 (AQP1) mostly apically, and ECs show mostly basolateral aquaporin-4 (AQP4) expression. Recent evidence in various systems has shown that in changing conditions the expression and distribution of AQP4 can be modified, involving phosphorylation and calmodulin-triggered translocation. Studies on the human CP revealed that AQP4 is also expressed in some CP cells, which is likely to be increased during ageing based on mouse data. Moreover, subependymal astrocytic processes in the ependyma-CP transition, forming a glial plate around blood vessels and facing the CP stroma, were strongly positive for AQP4. We propose that the increased AQP4 expression might be a compensatory mechanism for the observed reduction in CSF production in the ageing human brain. The high AQP4 density in the transition zone might facilitate the transport of water into and out of the CP stroma and serve as a drainage and clearing pathway for metabolites in the CNS.
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Affiliation(s)
- Andreas F Mack
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
| | - Ronja Bihlmaier
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
| | - Felix Deffner
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Tübingen, Germany
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Freiburg, Freiburg, Germany
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2
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Wang X, Ma S, Bai Y, Wu X, Ji F, Jia L. AQP4-DARPin1: A Chimeric Antigen Based on Scaffold Protein DARPin for Efficient Detection of AQP4-IgG in NMOSD. Biochemistry 2024; 63:855-864. [PMID: 38498694 DOI: 10.1021/acs.biochem.3c00688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
AQP4-IgG is an autoantibody associated with neuromyelitis optica spectroscopic disorder (NMOSD), a central nervous system inflammatory disease that requires early diagnosis and treatment. We designed two fusion proteins, AQP4-DARPin1 and AQP4-DARPin2, comprising the complete antigenic epitopes of aquaporin-4 (AQP4) and the constant region of the scaffold protein DARPin. These fusion proteins were expressed and purified from Escherichia coli and coated on microplates to develop an efficient method for detecting AQP4-IgG. Molecular dynamics simulation revealed that the fusion of AQP4 extracellular epitopes with DARPin did not alter the main structure of DARPin. The purified AQP4-DARPins bound recombinant antibody rAb-53 (AQP4-IgG) with affinities of 135 and 285 nM, respectively. Enzyme-linked immunosorbent assay (ELISA) and immunoprecipitation demonstrated that AQP4-DARPin1 specifically recognized AQP4-IgG in the NMOSD patient serum. AQP4-DARPin1 as a coated antigen showed higher ELISA signal and end point dilution ratio than full-length AQP4. Our AQP4-DARPin1-coated AQP4-IgG ELISA had 100% specificity and 90% sensitivity. These results indicate that AQP4-DARPin1, compared to existing detection strategies that use full-length or extracellular loop peptides of AQP4, provides a new and more effective approach to the ELISA detection of NMOSD.
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Affiliation(s)
- Xiaofei Wang
- Liaoning Key Laboratory of Molecular Recognition and Imaging, School of Bioengineering, Dalian University of Technology, Dalian 116023, P. R. China
| | - Shubei Ma
- Department of Neurology, Dalian Municipal Central Hospital, Dalian 116000, P. R. China
| | - Ying Bai
- Department of Neurology, Dalian University Affiliated Xinhua Hospital, Dalian 116021, P. R. China
| | - Xinyang Wu
- Liaoning Key Laboratory of Molecular Recognition and Imaging, School of Bioengineering, Dalian University of Technology, Dalian 116023, P. R. China
| | - Fangling Ji
- Liaoning Key Laboratory of Molecular Recognition and Imaging, School of Bioengineering, Dalian University of Technology, Dalian 116023, P. R. China
| | - Lingyun Jia
- Liaoning Key Laboratory of Molecular Recognition and Imaging, School of Bioengineering, Dalian University of Technology, Dalian 116023, P. R. China
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3
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Bhattacharjee A, Jana A, Bhattacharjee S, Mitra S, De S, Alghamdi BS, Alam MZ, Mahmoud AB, Al Shareef Z, Abdel-Rahman WM, Woon-Khiong C, Alexiou A, Papadakis M, Ashraf GM. The role of Aquaporins in tumorigenesis: implications for therapeutic development. Cell Commun Signal 2024; 22:106. [PMID: 38336645 PMCID: PMC10854195 DOI: 10.1186/s12964-023-01459-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 12/25/2023] [Indexed: 02/12/2024] Open
Abstract
Aquaporins (AQPs) are ubiquitous channel proteins that play a critical role in the homeostasis of the cellular environment by allowing the transit of water, chemicals, and ions. They can be found in many different types of cells and organs, including the lungs, eyes, brain, glands, and blood vessels. By controlling the osmotic water flux in processes like cell growth, energy metabolism, migration, adhesion, and proliferation, AQPs are capable of exerting their regulatory influence over a wide range of cellular processes. Tumour cells of varying sources express AQPs significantly, especially in malignant tumours with a high propensity for metastasis. New insights into the roles of AQPs in cell migration and proliferation reinforce the notion that AQPs are crucial players in tumour biology. AQPs have recently been shown to be a powerful tool in the fight against pathogenic antibodies and metastatic cell migration, despite the fact that the molecular processes of aquaporins in pathology are not entirely established. In this review, we shall discuss the several ways in which AQPs are expressed in the body, the unique roles they play in tumorigenesis, and the novel therapeutic approaches that could be adopted to treat carcinoma.
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Affiliation(s)
- Arkadyuti Bhattacharjee
- Morningside Graduate School of Biomedical Sciences, University of Massachusetts Medical School, Worcester, USA
| | - Ankit Jana
- Department of Biological Sciences, National University of Singapore, Singapore, 117558, Singapore
| | - Swagato Bhattacharjee
- KoshKey Sciences Pvt Ltd, Canara Bank Layout, Karnataka, Bengaluru, Rajiv Gandhi Nagar, Kodigehalli, 560065, India
| | - Sankalan Mitra
- KIIT School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT-DU), Bhubaneswar, Odisha, India
| | - Swagata De
- Department of English, DDE Unit, The University of Burdwan, Golapbag, Burdwan, West Bengal, 713104, India
| | - Badrah S Alghamdi
- Department of Physiology, Neuroscience Unit, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
- Pre-clinical Research Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mohammad Zubair Alam
- Pre-clinical Research Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia
- Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ahmad Bakur Mahmoud
- College of Applied Medical Sciences, Taibah University, Almadinah, Almunwarah, 71491, Saudi Arabia
| | - Zainab Al Shareef
- College of Medicine, and Research Institute for Medical and Health Sciences, Department of Basic Medical Sciences, University of Sharjah, Sharjah, 27272, United Arab Emirates
| | - Wael M Abdel-Rahman
- College of Health Sciences, and Research Institute for Medical and Health Sciences, Department of Medical Laboratory Sciences, University of Sharjah, Sharjah, 27272, United Arab Emirates
| | - Chan Woon-Khiong
- Department of Biological Sciences, National University of Singapore, Singapore, 117558, Singapore.
| | - Athanasios Alexiou
- University Centre for Research & Development, Chandigarh University, Chandigarh-Ludhiana Highway, Mohali, Punjab, India
- Department of Research & Development, Funogen, Athens, Greece
- Department of Research & Development, AFNP Med, 1030, Wien, Austria
- Department of Science and Engineering, Novel Global Community Educational Foundation, Hebersham, NSW, 2770, Australia
| | - Marios Papadakis
- Department of Surgery II, University Hospital Witten-Herdecke, Heusnerstrasse 40, University of Witten-Herdecke, 42283, Wuppertal, Germany.
| | - Ghulam Md Ashraf
- College of Health Sciences, and Research Institute for Medical and Health Sciences, Department of Medical Laboratory Sciences, University of Sharjah, Sharjah, 27272, United Arab Emirates.
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4
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Zhu B, Zhou W, Chen C, Cao A, Luo W, Huang C, Wang J. AQP4 is an Emerging Regulator of Pathological Pain: A Narrative Review. Cell Mol Neurobiol 2023; 43:3997-4005. [PMID: 37864629 DOI: 10.1007/s10571-023-01422-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 09/27/2023] [Indexed: 10/23/2023]
Abstract
Pathological pain presents significant challenges in clinical practice and research. Aquaporin-4 (AQP4), which is primarily found in astrocytes, is being considered as a prospective modulator of pathological pain. This review examines the association between AQP4 and pain-related diseases, including cancer pain, neuropathic pain, and inflammatory pain. In cancer pain, upregulated AQP4 expression in tumor cells is linked to increased pain severity, potentially through tumor-induced inflammation and edema. Targeting AQP4 may offer therapeutic strategies for managing cancer pain. AQP4 has also been found to play a role in nerve damage. Changes in AQP4 expression have been detected in pain-related regions of the brain and spinal cord; thus, modulating AQP4 expression or function may provide new avenues for treating neuropathic pain. Of note, AQP4-deficient mice exhibit reduced chronic pain responses, suggesting potential involvement of AQP4 in chronic pain modulation, and AQP4 is involved in pain modulation during inflammation, so understanding AQP4-mediated pain modulation may lead to novel anti-inflammatory and analgesic therapies. Recent advancements in magnetic resonance imaging (MRI) techniques enable assessment of AQP4 expression and localization, contributing to our understanding of its involvement in brain edema and clearance pathways related to pathological pain. Furthermore, targeting AQP4 through gene therapies and small-molecule modulators shows promise as a potential therapeutic intervention. Future research should focus on utilizing advanced MRI techniques to observe glymphatic system changes and the exchange of cerebrospinal fluid and interstitial fluid. Additionally, investigating the regulation of AQP4 by non-coding RNAs and exploring novel small-molecule medicines are important directions for future research. This review shed light on AQP4-based innovative therapeutic strategies for the treatment of pathological pain. Dark blue cells represent astrocytes, green cells represent microglia, and red ones represent brain microvasculature.
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Affiliation(s)
- Binbin Zhu
- Anesthesiology Department, The First Affiliated Hospital of Ningbo University, Ningbo, China
- Health Science Center, Ningbo University, Ningbo, China
- Radiology Department, The First Affiliated Hospital of Ningbo University, Ningbo, China
| | - Weijian Zhou
- Health Science Center, Ningbo University, Ningbo, China
- Radiology Department, The First Affiliated Hospital of Ningbo University, Ningbo, China
| | - Chunqu Chen
- Health Science Center, Ningbo University, Ningbo, China
- Radiology Department, The First Affiliated Hospital of Ningbo University, Ningbo, China
| | - Angyang Cao
- Anesthesiology Department, The First Affiliated Hospital of Ningbo University, Ningbo, China
- Health Science Center, Ningbo University, Ningbo, China
| | - Wenjun Luo
- Anesthesiology Department, The First Affiliated Hospital of Ningbo University, Ningbo, China
- Health Science Center, Ningbo University, Ningbo, China
| | - Changshun Huang
- Anesthesiology Department, The First Affiliated Hospital of Ningbo University, Ningbo, China.
| | - Jianhua Wang
- Health Science Center, Ningbo University, Ningbo, China.
- Radiology Department, The First Affiliated Hospital of Ningbo University, Ningbo, China.
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5
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Garcia TA, Jonak CR, Binder DK. The Role of Aquaporins in Spinal Cord Injury. Cells 2023; 12:1701. [PMID: 37443735 PMCID: PMC10340765 DOI: 10.3390/cells12131701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 06/08/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023] Open
Abstract
Edema formation following traumatic spinal cord injury (SCI) exacerbates secondary injury, and the severity of edema correlates with worse neurological outcome in human patients. To date, there are no effective treatments to directly resolve edema within the spinal cord. The aquaporin-4 (AQP4) water channel is found on plasma membranes of astrocytic endfeet in direct contact with blood vessels, the glia limitans in contact with the cerebrospinal fluid, and ependyma around the central canal. Local expression at these tissue-fluid interfaces allows AQP4 channels to play an important role in the bidirectional regulation of water homeostasis under normal conditions and following trauma. In this review, we consider the available evidence regarding the potential role of AQP4 in edema after SCI. Although more work remains to be carried out, the overall evidence indicates a critical role for AQP4 channels in edema formation and resolution following SCI and the therapeutic potential of AQP4 modulation in edema resolution and functional recovery. Further work to elucidate the expression and subcellular localization of AQP4 during specific phases after SCI will inform the therapeutic modulation of AQP4 for the optimization of histological and neurological outcomes.
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Affiliation(s)
- Terese A. Garcia
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
| | - Carrie R. Jonak
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
| | - Devin K. Binder
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
- Center for Glial-Neuronal Interactions, University of California, Riverside, CA 92521, USA
- Neuroscience Graduate Program, University of California, Riverside, CA 92521, USA
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6
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Sheikh AM, Yano S, Mitaki S, Tabassum S, Yamaguchi S, Nagai A. Rho-Kinase inhibition decreases focal cerebral ischemia-induced glial activation in rats. J Cent Nerv Syst Dis 2022; 14:11795735221123910. [PMID: 36106069 PMCID: PMC9465613 DOI: 10.1177/11795735221123910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 08/05/2022] [Indexed: 11/17/2022] Open
Abstract
Background Rho-kinase inhibition in a rat middle cerebral artery occlusion (MCAO) model
is reported to improve neurological functions and decrease infarction
size. Objective The objective of this study is to investigate the underlying mechanisms of
such improvement by evaluating the effects of Rho-kinase inhibition on
astrocytes and microglial accumulation and activation in this condition. Methods Adult male Sprague-Dawley (SD) rats were used to generate the MCAO model,
which received an I.P injection of a chemical Rho-kinase inhibitor (Fasudil-
5 mg/kg/day) or vehicle (PBS) for 2 and 4 days. Results Fasudil treatment significantly decreased the stroke volumes and water
content in the lesion areas, as revealed by MRI. Immunostaining and Western
blotting results demonstrated that Fasudil significantly decreased the
levels of Aquaporin-4, a water channel protein. The number of
GFAP+ astrocytes and Iba-1+ macrophage/microglia
was decreased in the lesion areas. Proinflammatory transcription factor
NF-κB protein levels were decreased in the Fasudil group 2 days after MCAO.
Also, proinflammatory mediators including TNF-α, IL-1β, and iNOS levels were
decreased. In vitro migration study using a human microglial cell line
(HMO6) confirmed the inhibitory effects of Fasudil on the process. Fasudil
also decreased combined IL-1β and IFNγ-induced NF-κB nuclear translocation
in HMO6. Moreover, Fasudil transiently decreased combined IL-1β and
IFNγ-induced iNOS, TNFα, and IL-1β mRNA levels in HMO6. Conclusion Our study demonstrates the inhibitory effects of Rho-kinase on NF-κB-mediated
glial activation and cerebral edema, which might be a promising therapeutic
target in acute cerebral ischemia conditions.
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Affiliation(s)
- Abdullah Md Sheikh
- Department of Laboratory Medicine, Shimane University Faculty of Medicine, Izumo, Japan
| | - Shozo Yano
- Department of Laboratory Medicine, Shimane University Faculty of Medicine, Izumo, Japan
| | - Shingo Mitaki
- Department of Neurology, Shimane University Faculty of Medicine, Izumo, Japan
| | - Shatera Tabassum
- Department of Laboratory Medicine, Shimane University Faculty of Medicine, Izumo, Japan
| | | | - Atsushi Nagai
- Department of Neurology, Shimane University Faculty of Medicine, Izumo, Japan
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7
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Abe Y, Yasui M. Aquaporin-4 in Neuromyelitis Optica Spectrum Disorders: A Target of Autoimmunity in the Central Nervous System. Biomolecules 2022; 12:biom12040591. [PMID: 35454180 PMCID: PMC9030581 DOI: 10.3390/biom12040591] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 04/11/2022] [Accepted: 04/12/2022] [Indexed: 12/20/2022] Open
Abstract
Since the discovery of a specific autoantibody in patients with neuromyelitis optica spectrum disorder (NMOSD) in 2004, the water channel aquaporin-4 (AQP4) has attracted attention as a target of autoimmune diseases of the central nervous system. In NMOSD, the autoantibody (NMO-IgG) binds to the extracellular loops of AQP4 as expressed in perivascular astrocytic end-feet and disrupts astrocytes in a complement-dependent manner. NMO-IgG is an excellent marker for distinguishing the disease from other inflammatory demyelinating diseases, such as multiple sclerosis. The unique higher-order structure of AQP4—called orthogonal arrays of particles (OAPs)—as well as its subcellular localization may play a crucial role in the pathogenesis of the disease. Recent studies have also demonstrated complement-independent cytotoxic effects of NMO-IgG. Antibody-induced endocytosis of AQP4 has been suggested to be involved in this mechanism. This review focuses on the binding properties of antibodies that recognize the extracellular region of AQP4 and the characteristics of AQP4 that are implicated in the pathogenesis of NMOSD.
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Affiliation(s)
- Yoichiro Abe
- Department of Pharmacology, Keio University School of Medicine, Tokyo 160-8582, Japan
- Keio University Global Research Institute, Tokyo 108-8345, Japan
- Correspondence: (Y.A.); (M.Y.); Tel.: +81-3-5363-3751 (M.Y.)
| | - Masato Yasui
- Department of Pharmacology, Keio University School of Medicine, Tokyo 160-8582, Japan
- Keio University Global Research Institute, Tokyo 108-8345, Japan
- Correspondence: (Y.A.); (M.Y.); Tel.: +81-3-5363-3751 (M.Y.)
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8
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Salman MM, Kitchen P, Halsey A, Wang MX, Törnroth-Horsefield S, Conner AC, Badaut J, Iliff JJ, Bill RM. Emerging roles for dynamic aquaporin-4 subcellular relocalization in CNS water homeostasis. Brain 2022; 145:64-75. [PMID: 34499128 PMCID: PMC9088512 DOI: 10.1093/brain/awab311] [Citation(s) in RCA: 103] [Impact Index Per Article: 51.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 06/28/2021] [Accepted: 07/31/2021] [Indexed: 11/25/2022] Open
Abstract
Aquaporin channels facilitate bidirectional water flow in all cells and tissues. AQP4 is highly expressed in astrocytes. In the CNS, it is enriched in astrocyte endfeet, at synapses, and at the glia limitans, where it mediates water exchange across the blood-spinal cord and blood-brain barriers (BSCB/BBB), and controls cell volume, extracellular space volume, and astrocyte migration. Perivascular enrichment of AQP4 at the BSCB/BBB suggests a role in glymphatic function. Recently, we have demonstrated that AQP4 localization is also dynamically regulated at the subcellular level, affecting membrane water permeability. Ageing, cerebrovascular disease, traumatic CNS injury, and sleep disruption are established and emerging risk factors in developing neurodegeneration, and in animal models of each, impairment of glymphatic function is associated with changes in perivascular AQP4 localization. CNS oedema is caused by passive water influx through AQP4 in response to osmotic imbalances. We have demonstrated that reducing dynamic relocalization of AQP4 to the BSCB/BBB reduces CNS oedema and accelerates functional recovery in rodent models. Given the difficulties in developing pore-blocking AQP4 inhibitors, targeting AQP4 subcellular localization opens up new treatment avenues for CNS oedema, neurovascular and neurodegenerative diseases, and provides a framework to address fundamental questions about water homeostasis in health and disease.
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Affiliation(s)
- Mootaz M Salman
- Department of Physiology, Anatomy and Genetics,
University of Oxford, Oxford OX1 3PT, UK
| | - Philip Kitchen
- School of Biosciences, College of Health and Life
Sciences, Aston University, Aston Triangle,
Birmingham B4 7ET, UK
| | - Andrea Halsey
- Institute of Clinical Sciences, College of Medical
and Dental Sciences, University of Birmingham,
Edgbaston, Birmingham B15 2TT, UK
| | - Marie Xun Wang
- Department of Psychiatry and Behavioral Sciences,
University of Washington School of Medicine, Seattle, WA, USA
| | | | - Alex C Conner
- Institute of Clinical Sciences, College of Medical
and Dental Sciences, University of Birmingham,
Edgbaston, Birmingham B15 2TT, UK
| | - Jerome Badaut
- CNRS-UMR 5536-Centre de Résonance
Magnétique des systèmes Biologiques, Université de
Bordeaux, 33076 Bordeaux, France
| | - Jeffrey J Iliff
- Department of Psychiatry and Behavioral Sciences,
University of Washington School of Medicine, Seattle, WA, USA
- Department of Neurology, University of Washington
School of Medicine, Seattle, WA, USA
- VISN 20 Mental Illness Research, Education and
Clinical Center, VA Puget Sound Health Care System, Seattle, WA,
USA
| | - Roslyn M Bill
- School of Biosciences, College of Health and Life
Sciences, Aston University, Aston Triangle,
Birmingham B4 7ET, UK
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9
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Deffner F, Gleiser C, Mattheus U, Wagner A, Neckel PH, Fallier-Becker P, Hirt B, Mack AF. Aquaporin-4 expression in the human choroid plexus. Cell Mol Life Sci 2022; 79:90. [PMID: 35072772 PMCID: PMC8785037 DOI: 10.1007/s00018-022-04136-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 01/02/2022] [Accepted: 01/05/2022] [Indexed: 01/15/2023]
Abstract
The choroid plexus (CP) consists of specialized ependymal cells and underlying blood vessels and stroma producing the bulk of the cerebrospinal fluid (CSF). CP epithelial cells are considered the site of the internal blood-cerebrospinal fluid barrier, show epithelial characteristics (basal lamina, tight junctions), and express aquaporin-1 (AQP1) apically. In this study, we analyzed the expression of aquaporins in the human CP using immunofluorescence and qPCR. As previously reported, AQP1 was expressed apically in CP epithelial cells. Surprisingly, and previously unknown, many cells in the CP epithelium were also positive for aquaporin-4 (AQP4), normally restricted to ventricle-lining ependymal cells and astrocytes in the brain. Expression of AQP1 and AQP4 was found in the CP of all eight body donors investigated (3 males, 5 females; age 74–91). These results were confirmed by qPCR, and by electron microscopy detecting orthogonal arrays of particles. To find out whether AQP4 expression correlated with the expression pattern of relevant transport-related proteins we also investigated expression of NKCC1, and Na/K-ATPase. Immunostaining with NKCC1 was similar to AQP1 and revealed no particular pattern related to AQP4. Co-staining of AQP4 and Na/K-ATPase indicated a trend for an inverse correlation of their expression. We hypothesized that AQP4 expression in the CP was caused by age-related changes. To address this, we investigated mouse brains from young (2 months), adult (12 months) and old (30 months) mice. We found a significant increase of AQP4 on the mRNA level in old mice compared to young and adult animals. Taken together, we provide evidence for AQP4 expression in the CP of the aging brain which likely contributes to the water flow through the CP epithelium and CSF production. In two alternative hypotheses, we discuss this as a beneficial compensatory, or a detrimental mechanism influencing the previously observed CSF changes during aging.
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Affiliation(s)
- Felix Deffner
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Österbergstr. 3, 72074, Tübingen, Germany
| | - Corinna Gleiser
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Österbergstr. 3, 72074, Tübingen, Germany
| | - Ulrich Mattheus
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Österbergstr. 3, 72074, Tübingen, Germany
| | - Andreas Wagner
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Österbergstr. 3, 72074, Tübingen, Germany
| | - Peter H Neckel
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Österbergstr. 3, 72074, Tübingen, Germany
| | - Petra Fallier-Becker
- Institute of Pathology and Neuropathology, University of Tübingen, Tübingen, Germany
| | - Bernhard Hirt
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Österbergstr. 3, 72074, Tübingen, Germany
| | - Andreas F Mack
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Österbergstr. 3, 72074, Tübingen, Germany.
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10
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Cibelli A, Stout R, Timmermann A, de Menezes L, Guo P, Maass K, Seifert G, Steinhäuser C, Spray DC, Scemes E. Cx43 carboxyl terminal domain determines AQP4 and Cx30 endfoot organization and blood brain barrier permeability. Sci Rep 2021; 11:24334. [PMID: 34934080 PMCID: PMC8692511 DOI: 10.1038/s41598-021-03694-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 12/06/2021] [Indexed: 11/08/2022] Open
Abstract
The neurovascular unit (NVU) consists of cells intrinsic to the vessel wall, the endothelial cells and pericytes, and astrocyte endfeet that surround the vessel but are separated from it by basement membrane. Endothelial cells are primarily responsible for creating and maintaining blood-brain-barrier (BBB) tightness, but astrocytes contribute to the barrier through paracrine signaling to the endothelial cells and by forming the glia limitans. Gap junctions (GJs) between astrocyte endfeet are composed of connexin 43 (Cx43) and Cx30, which form plaques between cells. GJ plaques formed of Cx43 do not diffuse laterally in the plasma membrane and thus potentially provide stable organizational features to the endfoot domain, whereas GJ plaques formed of other connexins and of Cx43 lacking a large portion of its cytoplasmic carboxyl terminus are quite mobile. In order to examine the organizational features that immobile GJs impose on the endfoot, we have used super-resolution confocal microscopy to map number and sizes of GJ plaques and aquaporin (AQP)-4 channel clusters in the perivascular endfeet of mice in which astrocyte GJs (Cx30, Cx43) were deleted or the carboxyl terminus of Cx43 was truncated. To determine if BBB integrity was compromised in these transgenic mice, we conducted perfusion studies under elevated hydrostatic pressure using horseradish peroxide as a molecular probe enabling detection of micro-hemorrhages in brain sections. These studies revealed that microhemorrhages were more numerous in mice lacking Cx43 or its carboxyl terminus. In perivascular domains of cerebral vessels, we found that density of Cx43 GJs was higher in the truncation mutant, while GJ size was smaller. Density of perivascular particles formed by AQP4 and its extended isoform AQP4ex was inversely related to the presence of full length Cx43, whereas the ratio of sizes of the particles of the AQP4ex isoform to total AQP4 was directly related to the presence of full length Cx43. Confocal analysis showed that Cx43 and Cx30 were substantially colocalized in astrocyte domains near vasculature of truncation mutant mice. These results showing altered distribution of some astrocyte nexus components (AQP4 and Cx30) in Cx43 null mice and in a truncation mutant, together with leakier cerebral vasculature, support the hypothesis that localization and mobility of gap junction proteins and their binding partners influences organization of astrocyte endfeet which in turn impacts BBB integrity of the NVU.
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Affiliation(s)
- Antonio Cibelli
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Randy Stout
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- New York Institute of Technology College of Osteopathic Medicine, Old Westbury, NY, USA
| | - Aline Timmermann
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Laura de Menezes
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Insitute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Peng Guo
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Cellular Imaging Core Facility, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Karen Maass
- Cardiovascular Research Center, NYU Grossman School of Medicine, New York, NY, USA
| | - Gerald Seifert
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - David C Spray
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA.
| | - Eliana Scemes
- Department of Anatomy and Cell Biology, New York Medical College, Valhalla, NY, 10595, USA.
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11
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Pisani F, Simone L, Mola MG, De Bellis M, Frigeri A, Nicchia GP, Svelto M. Regulation of aquaporin-4 expression in the central nervous system investigated using M23-AQP4 null mouse. Glia 2021; 69:2235-2251. [PMID: 34038017 PMCID: PMC8361696 DOI: 10.1002/glia.24032] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 04/15/2021] [Accepted: 05/17/2021] [Indexed: 12/22/2022]
Abstract
In astrocytes, unknown mechanisms regulate the expression of M1 and M23 isoforms of water channel aquaporin-4 (M1-AQP4 and M23-AQP4). The ratio between these two isoforms controls the AQP4 assembly state in the plasma membrane known as orthogonal arrays of particles (OAPs). To give new insights into these mechanisms, here, we explore the regulation of AQP4 expression in the spinal cord of a CRISPR/Cas9 M23-null mouse model (M23-null). In the M23-null spinal cord OAP assembly, the perivascular localization of AQP4 and M1-AQP4 protein were drastically reduced. In heterozygous, M1-AQP4 was proportionally reduced with M23-AQP4, maintaining the isoform ratio unaffected. We hypothesize a role of the M23-AQP4 in the regulation of M1-AQP4 expression. M1-AQP4 transcription, splicing and M1-AQP4 protein degradation were found to be unaffected in M23-null spinal cord and in M23-null astrocyte primary culture. The translational control was investigated by mRNA-protein pull down and quantitative mass spectrometry, to isolate and quantify AQP4 mRNA binding proteins (AQP4-RBPs). Compared to WT, in M23-null spinal cord, the interaction between AQP4 mRNA and polypyrimidine tract binding protein 1, a positive regulator of AQP4 translation, was higher, while interaction with the RNA helicase DDX17 was lower. In astrocyte primary cultures, DDX17 knockdown upregulated AQP4 protein expression and increased cell swelling, leaving AQP4 mRNA levels unchanged. Here, we identify AQP4-RBPs and provide evidence that in mouse spinal cord M23-AQP4 deletion changes the interaction between AQP4 mRNA and some RBPs involved in AQP4 translation. We describe for the first time the RNA helicase DDX17 as a regulator of AQP4 expression in astrocytes.
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Affiliation(s)
- Francesco Pisani
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, Bari, Italy
| | - Laura Simone
- Fondazione IRCCS Casa Sollievo della Sofferenza, Cancer Stem Cells Unit, San Giovanni Rotondo (FG), Italy
| | - Maria Grazia Mola
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, Bari, Italy
| | - Manuela De Bellis
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, Bari, Italy
| | - Antonio Frigeri
- School of Medicine, Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari Aldo Moro, Bari, Italy
| | - Grazia Paola Nicchia
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, Bari, Italy
| | - Maria Svelto
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, Bari, Italy.,Institute of Biomembranes and Bioenergetics, National Research Council, Bari, Italy.,National Institute of Biostructures and Biosystems (INBB), Rome, Italy
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