Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
8.3
5.5
Journals
Biomolecules
Special Issues
Aquaporins in the CNS–in Honor of the 30th Anniversary of...
share announcement

Aquaporins in the CNS–in Honor of the 30th Anniversary of the Discovery of Aquaporins

A special issue of Biomolecules (ISSN 2218-273X). This special issue belongs to the section "Cellular Biochemistry".

Deadline for manuscript submissions: closed (30 September 2022) | Viewed by 15111

Special Issue Editor

Prof. Dr. Mahmood Amiry-Moghaddam

E-Mail Website
Guest Editor
Laboratory of Molecular Neuroscience, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, P.O. Box 1105, Blindern, 0317 Oslo, Norway
Interests: brain and nervous system; cell volume regulation; aquaporins; astrocytes; neurodegenerative disorders; neuroinflammation

Special Issue Information

Dear Colleagues,

Nearly 30 years have passed since the discovery of the first member of the aquaporin family by Agre and colleagues in 1992. The discovery of the aquaporins marked the end of a long-standing conundrum in biology and paved the way for a molecular understanding of secretion and absorption processes in animals, plants, and microbials.

In 1994, Agre’s and Verkman’s groups independently reported the existence of a new aquaporin cDNA which is highly expressed in brain. This aquaporin, later named AQP4, is mainly expressed in astrocytes and ependymal cells of the ventricles. Research in the following two and a half decades has shown that AQP4 plays an important role in water and ion homeostasis and is involved in pathological conditions such as brain edema, epilepsy, and neurodegenerative disorders. A special focus has been given to the role of AQP4 in the glymphatic system and brain waste clearance in recent years. Less is known, on the other hand, about the signaling pathways regulating AQP4’s expression and function.

AQP1 and AQP9 are the other two major aquaporins demonstrated in the central nervous  system (CNS). Both AQPs are implicated in several pathological conditions, but there are still many questions around their pathophysiological relevance.

The aim of this Special Issue is to shed light on some of the central questions regarding the physiological and pathological roles of aquaporins in the CNS. We specifically welcome original articles and reviews discussing signaling pathways regulating expression, function, and pathophysiological relevance of the CNS aquaporins.  

I look forward to receiving your contributions.

Prof. Dr. Mahmood Amiry-Moghaddam
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Biomolecules is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Aquaporins
  • AQP4
  • AQP9
  • AQP1
  • Astrocytes
  • Neurological diseases
  • Signaling pathways
  • Inflammation
  • Blood–brain barrier

Published Papers (5 papers)

Download All Papers
Order results
Result details
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:

Research

Jump to: Review

14 pages, 11473 KiB  
Article
Aquaporin-9 in the Brain Inflammatory Response: Evidence from Mice Injected with the Parkinsonogenic Toxin MPP+
by Soulmaz Zahl, Nadia Skauli, Katja Stahl, Agnete Prydz, Mina Martine Frey, Erik Dissen, Ole Petter Ottersen and Mahmood Amiry-Moghaddam
Biomolecules 2023, 13(4), 588; https://doi.org/10.3390/biom13040588 - 24 Mar 2023
Viewed by 1548
Abstract
More than 20 years have passed since the first demonstration of Aquaporin-9 (AQP9) in the brain. Yet its precise localization and function in brain tissue remain unresolved. In peripheral tissues, AQP9 is expressed in leukocytes where it is involved in systemic inflammation processes. [...] Read more.
More than 20 years have passed since the first demonstration of Aquaporin-9 (AQP9) in the brain. Yet its precise localization and function in brain tissue remain unresolved. In peripheral tissues, AQP9 is expressed in leukocytes where it is involved in systemic inflammation processes. In this study, we hypothesized that AQP9 plays a proinflammatory role in the brain, analogous to its role in the periphery. We also explored whether Aqp9 is expressed in microglial cells, which would be supportive of this hypothesis. Our results show that targeted deletion of Aqp9 significantly suppressed the inflammatory response to the parkinsonian toxin 1-methyl-4-phenylpyridinium (MPP+). This toxin induces a strong inflammatory response in brain. After intrastriatal injections of MPP+, the increase in transcript levels of proinflammatory genes was less pronounced in AQP9−/− mice compared with wild-type controls. Further, in isolated cell subsets, validated by flow cytometry we demonstrated that Aqp9 transcripts are expressed in microglial cells, albeit at lower concentrations than in astrocytes. The present analysis provides novel insight into the role of AQP9 in the brain and opens new avenues for research in the field of neuroinflammation and chronic neurodegenerative disease. Full article
(This article belongs to the Special Issue Aquaporins in the CNS–in Honor of the 30th Anniversary of the Discovery of Aquaporins)
►▼ Show Figures

Figure 1

13 pages, 2207 KiB  
Article
Aquaporin-1 and Aquaporin-4 Expression in Ependyma, Choroid Plexus and Surrounding Transition Zones in the Human Brain
by Ronja Bihlmaier, Felix Deffner, Ulrich Mattheus, Peter H. Neckel, Bernhard Hirt and Andreas F. Mack
Biomolecules 2023, 13(2), 212; https://doi.org/10.3390/biom13020212 - 22 Jan 2023
Cited by 3 | Viewed by 2128
Abstract
The choroid plexus (CP) is a structure in the brain ventricles that produces the main part of the cerebrospinal fluid (CSF). It is covered with specialized cells which show epithelial characteristics and are the site of the blood–CSF barrier. These cells form a [...] Read more.
The choroid plexus (CP) is a structure in the brain ventricles that produces the main part of the cerebrospinal fluid (CSF). It is covered with specialized cells which show epithelial characteristics and are the site of the blood–CSF barrier. These cells form a contiguous cell sheet with ventricle-lining ependymal cells which are known to express aquaporin-4 (AQP4). In contrast, CP epithelial cells express aquaporin-1 (AQP1) apically. We investigated the expression patterns of aquaporins in the CP-ependyma transition from human body donors using immunofluorescence and electron microscopy. Ependymal cells and subependymal astrocytes at the base of the CP showed a particularly high AQP4 immunoreactivity. Astrocytic processes formed a dense meshwork or glial plate around the blood vessels entering the CP. Interestingly, some of these astrocytic processes were in direct contact with the CP stroma, which contains fenestrated blood vessels, separated only by a basal lamina. Electron microscopy confirmed the continuity of the subastrocytic basal lamina with the CP epithelium. We also probed for components of the AQP4 anchoring dystrophin–dystroglycan complex. Immunolabeling for dystrophin and AQP4 showed an overlapping staining pattern in the glial plate but not in previously reported AQP4-positive CP epithelial cells. In contrast, dystroglycan expression was associated with laminin staining in the glial plate and the CP epithelium. This suggests different mechanisms for AQP4 anchoring in the cell membrane. The high AQP4 density in the connecting glial plate might facilitate the transport of water in and out of the CP stroma and could possibly serve as a drainage and clearing pathway for metabolites. Full article
(This article belongs to the Special Issue Aquaporins in the CNS–in Honor of the 30th Anniversary of the Discovery of Aquaporins)
►▼ Show Figures

Figure 1

11 pages, 2120 KiB  
Article
The Readthrough Isoform AQP4ex Is Constitutively Phosphorylated in the Perivascular Astrocyte Endfeet of Human Brain
by Roberta Pati, Claudia Palazzo, Onofrio Valente, Pasqua Abbrescia, Raffaella Messina, Nicoletta Concetta Surdo, Konstantinos Lefkimmiatis, Francesco Signorelli, Grazia Paola Nicchia and Antonio Frigeri
Biomolecules 2022, 12(5), 633; https://doi.org/10.3390/biom12050633 - 25 Apr 2022
Cited by 6 | Viewed by 2108
Abstract
AQP4ex is a recently discovered isoform of AQP4 generated by a translational readthrough mechanism. It is strongly expressed at the astrocyte perivascular endfeet as a component of the supramolecular membrane complex, commonly called orthogonal array of particles (OAP), together with the canonical isoforms [...] Read more.
AQP4ex is a recently discovered isoform of AQP4 generated by a translational readthrough mechanism. It is strongly expressed at the astrocyte perivascular endfeet as a component of the supramolecular membrane complex, commonly called orthogonal array of particles (OAP), together with the canonical isoforms M1 and M23 of AQP4. Previous site-directed mutagenesis experiments suggested the potential role of serine331 and serine335, located in the extended peptide of AQP4ex, in water channel activity by phosphorylation. In the present study we evaluated the effective phosphorylation of human AQP4ex. A small scale bioinformatic analysis indicated that only Ser335 is conserved in human, mouse and rat AQP4ex. The phosphorylation site of Ser335 was assessed through generation of phospho-specific antibodies in rabbits. Antibody specificity was first evaluated in binding phosphorylated peptide versus its unphosphorylated analog by ELISA, which was further confirmed by site-directed mutagenesis experiments. Western blot and immunofluorescence experiments revealed strong expression of phosphorylated AQP4ex (p-AQP4ex) in human brain and localization at the perivascular astrocyte endfeet in supramolecular assemblies identified by BN/PAGE experiments. All together, these data reveal, for the first time, the existence of a phosphorylated form of AQP4, at Ser335 in the extended sequence exclusive of AQP4ex. Therefore, we anticipate an important physiological role of p-AQP4ex in human brain water homeostasis. Full article
(This article belongs to the Special Issue Aquaporins in the CNS–in Honor of the 30th Anniversary of the Discovery of Aquaporins)
►▼ Show Figures

Figure 1

Review

Jump to: Research

14 pages, 1564 KiB  
Review
Aquaporin-4 in Neuromyelitis Optica Spectrum Disorders: A Target of Autoimmunity in the Central Nervous System
by Yoichiro Abe and Masato Yasui
Biomolecules 2022, 12(4), 591; https://doi.org/10.3390/biom12040591 - 17 Apr 2022
Cited by 14 | Viewed by 3684
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Aquaporins in the CNS–in Honor of the 30th Anniversary of the Discovery of Aquaporins)
►▼ Show Figures

Figure 1

18 pages, 4471 KiB  
Review
Cellular Distribution of Brain Aquaporins and Their Contribution to Cerebrospinal Fluid Homeostasis and Hydrocephalus
by José Luis Trillo-Contreras, Reposo Ramírez-Lorca, Javier Villadiego and Miriam Echevarría
Biomolecules 2022, 12(4), 530; https://doi.org/10.3390/biom12040530 - 31 Mar 2022
Cited by 11 | Viewed by 2760
Abstract
Brain aquaporins facilitate the movement of water between the four water compartments: blood, cerebrospinal fluid, interstitial fluid, and intracellular fluid. This work analyzes the expression of the four most abundant aquaporins (AQPs) (AQP1, AQP4, AQP9, and AQP11) in the brains of mice and [...] Read more.
Brain aquaporins facilitate the movement of water between the four water compartments: blood, cerebrospinal fluid, interstitial fluid, and intracellular fluid. This work analyzes the expression of the four most abundant aquaporins (AQPs) (AQP1, AQP4, AQP9, and AQP11) in the brains of mice and discuss their contribution to hydrocephalus. We analyzed available data from single-cell RNA sequencing of the central nervous system of mice to describe the expression of aquaporins and compare their distribution with that based on qPCR, western blot, and immunohistochemistry assays. Expression of AQP1 in the apical cell membrane of choroid plexus epithelial cells and of AQP4 in ependymal cells, glia limitans, and astrocyte processes in the pericapillary end foot is consistent with the involvement of both proteins in cerebrospinal fluid homeostasis. The expression of both aquaporins compensates for experimentally induced hydrocephalus in the animals. Recent data demonstrate that hypoxia in aged animals alters AQP4 expression in the choroidal plexus and cortex, increasing the ventricle size and intraventricular pressure. Cerebral distensibility is reduced in parallel with a reduction in cerebrospinal fluid drainage and cognitive deterioration. We propose that aged mice chronically exposed to hypoxia represent an excellent experimental model for studying the pathophysiological characteristics of idiopathic normal pressure hydrocephalus and roles for AQPs in such disease. Full article
(This article belongs to the Special Issue Aquaporins in the CNS–in Honor of the 30th Anniversary of the Discovery of Aquaporins)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-5
Back to TopTop