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Mayo F, González-Vinceiro L, Hiraldo-González L, Rodríguez-Gómez FD, Calle-Castillejo C, Mayo M, Netti V, Ramírez-Lorca R, Echevarría M. Impact of aquaporin-4 and CD11c + microglia in the development of ependymal cells in the aqueduct: inferences to hydrocephalus. Fluids Barriers CNS 2024; 21:53. [PMID: 38956598 PMCID: PMC11221146 DOI: 10.1186/s12987-024-00548-2] [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: 12/03/2023] [Accepted: 05/07/2024] [Indexed: 07/04/2024] Open
Abstract
AQP4 is expressed in the endfeet membranes of subpial and perivascular astrocytes and in the ependymal cells that line the ventricular system. The sporadic appearance of obstructive congenital hydrocephalus (OCHC) has been observed in the offspring of AQP4-/- mice (KO) due to stenosis of Silvio's aqueduct. Here, we explore whether the lack of AQP4 expression leads to abnormal development of ependymal cells in the aqueduct of mice. We compared periaqueductal samples from wild-type and KO mice. The microarray-based transcriptome analysis reflected a large number of genes with differential expression (809). Gene sets (GS) associated with ependymal development, ciliary function and the immune system were specially modified qPCR confirmed reduced expression in the KO mice genes: (i) coding for transcription factors for ependymal differentiation (Rfx4 and FoxJ1), (ii) involved in the constitution of the central apparatus of the axoneme (Spag16 and Hydin), (iii) associated with ciliary assembly (Cfap43, Cfap69 and Ccdc170), and (iv) involved in intercellular junction complexes of the ependyma (Cdhr4). By contrast, genes such as Spp1, Gpnmb, Itgax, and Cd68, associated with a Cd11c-positive microglial population, were overexpressed in the KO mice. Electron microscopy and Immunofluorescence of vimentin and γ-tubulin revealed a disorganized ependyma in the KO mice, with changes in the intercellular complex union, unevenly orientated cilia, and variations in the planar cell polarity of the apical membrane. These structural alterations translate into reduced cilia beat frequency, which might alter cerebrospinal fluid movement. The presence of CD11c + microglia cells in the periaqueductal zone of mice during the first postnatal week is a novel finding. In AQP4-/- mice, these cells remain present around the aqueduct for an extended period, showing peak expression at P11. We propose that these cells play an important role in the normal development of the ependyma and that their overexpression in KO mice is crucial to reduce ependyma abnormalities that could otherwise contribute to the development of obstructive hydrocephalus.
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Affiliation(s)
- Francisco Mayo
- Instituto de Biomedicina de Sevilla, IBiS/Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Av. Manuel Siurot s/n, 41013, Seville, Spain
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009, Seville, Spain
| | - Lourdes González-Vinceiro
- Instituto de Biomedicina de Sevilla, IBiS/Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Av. Manuel Siurot s/n, 41013, Seville, Spain
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009, Seville, Spain
| | - Laura Hiraldo-González
- Instituto de Biomedicina de Sevilla, IBiS/Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Av. Manuel Siurot s/n, 41013, Seville, Spain
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009, Seville, Spain
| | - Francisco D Rodríguez-Gómez
- Instituto de Biomedicina de Sevilla, IBiS/Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Av. Manuel Siurot s/n, 41013, Seville, Spain
| | - Claudia Calle-Castillejo
- Instituto de Biomedicina de Sevilla, IBiS/Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Av. Manuel Siurot s/n, 41013, Seville, Spain
| | - Manuel Mayo
- Física Teórica, Universidad de Sevilla, Apartado de Correos 1065, 41080, Seville, Spain
| | - Vanina Netti
- Facultad de Medicina, Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas, Universidad de Buenos Aires- CONICET, Instituto de Fisiología y Biofísica ''Bernardo Houssay'' (IFIBIO-HOUSSAY), Buenos Aires, Argentina
| | - Reposo Ramírez-Lorca
- Instituto de Biomedicina de Sevilla, IBiS/Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Av. Manuel Siurot s/n, 41013, Seville, Spain
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009, Seville, Spain
| | - Miriam Echevarría
- Instituto de Biomedicina de Sevilla, IBiS/Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Av. Manuel Siurot s/n, 41013, Seville, Spain.
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009, Seville, Spain.
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2
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Markou A, Kitchen P, Aldabbagh A, Repici M, Salman MM, Bill RM, Balklava Z. Mechanisms of aquaporin-4 vesicular trafficking in mammalian cells. J Neurochem 2024; 168:100-114. [PMID: 38102893 PMCID: PMC10953025 DOI: 10.1111/jnc.16029] [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: 06/30/2023] [Revised: 11/24/2023] [Accepted: 12/02/2023] [Indexed: 12/17/2023]
Abstract
The aquaporin-4 (AQP4) water channel is abundantly expressed in the glial cells of the central nervous system and facilitates brain swelling following diverse insults, such as traumatic injury or stroke. Lack of specific and therapeutic AQP4 inhibitors highlights the need to explore alternative routes to control the water permeability of glial cell membranes. The cell surface abundance of AQP4 in mammalian cells fluctuates rapidly in response to changes in oxygen levels and tonicity, suggesting a role for vesicular trafficking in its translocation to and from the cell surface. However, the molecular mechanisms of AQP4 trafficking are not fully elucidated. In this work, early and recycling endosomes were investigated as likely candidates of rapid AQP4 translocation together with changes in cytoskeletal dynamics. In transiently transfected HEK293 cells a significant amount of AQP-eGFP colocalised with mCherry-Rab5-positive early endosomes and mCherry-Rab11-positive recycling endosomes. When exposed to hypotonic conditions, AQP4-eGFP rapidly translocated from intracellular vesicles to the cell surface. Co-expression of dominant negative forms of the mCherry-Rab5 and -Rab11 with AQP4-eGFP prevented hypotonicity-induced AQP4-eGFP trafficking and led to concentration at the cell surface or intracellular vesicles respectively. Use of endocytosis inhibiting drugs indicated that AQP4 internalisation was dynamin-dependent. Cytoskeleton dynamics-modifying drugs also affected AQP4 translocation to and from the cell surface. AQP4 trafficking mechanisms were validated in primary human astrocytes, which express high levels of endogenous AQP4. The results highlight the role of early and recycling endosomes and cytoskeletal dynamics in AQP4 translocation in response to hypotonic and hypoxic stress and suggest continuous cycling of AQP4 between intracellular vesicles and the cell surface under physiological conditions.
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Affiliation(s)
- Andrea Markou
- College of Health and Life SciencesAston UniversityBirminghamUK
- School of Biosciences, Faculty of Health and Medical SciencesUniversity of SurreyGuildfordUK
| | - Philip Kitchen
- College of Health and Life SciencesAston UniversityBirminghamUK
| | - Ahmed Aldabbagh
- College of Health and Life SciencesAston UniversityBirminghamUK
| | | | - Mootaz M. Salman
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
- Kavli Institute for NanoScience DiscoveryUniversity of OxfordOxfordUK
| | - Roslyn M. Bill
- College of Health and Life SciencesAston UniversityBirminghamUK
| | - Zita Balklava
- College of Health and Life SciencesAston UniversityBirminghamUK
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3
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Žugec M, Furlani B, Castañon MJ, Rituper B, Fischer I, Broggi G, Caltabiano R, Barbagallo GMV, Di Rosa M, Tibullo D, Parenti R, Vicario N, Simčič S, Pozo Devoto VM, Stokin GB, Wiche G, Jorgačevski J, Zorec R, Potokar M. Plectin plays a role in the migration and volume regulation of astrocytes: a potential biomarker of glioblastoma. J Biomed Sci 2024; 31:14. [PMID: 38263015 PMCID: PMC10807171 DOI: 10.1186/s12929-024-01002-z] [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: 07/10/2023] [Accepted: 01/09/2024] [Indexed: 01/25/2024] Open
Abstract
BACKGROUND The expression of aquaporin 4 (AQP4) and intermediate filament (IF) proteins is altered in malignant glioblastoma (GBM), yet the expression of the major IF-based cytolinker, plectin (PLEC), and its contribution to GBM migration and invasiveness, are unknown. Here, we assessed the contribution of plectin in affecting the distribution of plasmalemmal AQP4 aggregates, migratory properties, and regulation of cell volume in astrocytes. METHODS In human GBM, the expression of glial fibrillary acidic protein (GFAP), AQP4 and PLEC transcripts was analyzed using publicly available datasets, and the colocalization of PLEC with AQP4 and with GFAP was determined by immunohistochemistry. We performed experiments on wild-type and plectin-deficient primary and immortalized mouse astrocytes, human astrocytes and permanent cell lines (U-251 MG and T98G) derived from a human malignant GBM. The expression of plectin isoforms in mouse astrocytes was assessed by quantitative real-time PCR. Transfection, immunolabeling and confocal microscopy were used to assess plectin-induced alterations in the distribution of the cytoskeleton, the influence of plectin and its isoforms on the abundance and size of plasmalemmal AQP4 aggregates, and the presence of plectin at the plasma membrane. The release of plectin from cells was measured by ELISA. The migration and dynamics of cell volume regulation of immortalized astrocytes were assessed by the wound-healing assay and calcein labeling, respectively. RESULTS A positive correlation was found between plectin and AQP4 at the level of gene expression and protein localization in tumorous brain samples. Deficiency of plectin led to a decrease in the abundance and size of plasmalemmal AQP4 aggregates and altered distribution and bundling of the cytoskeleton. Astrocytes predominantly expressed P1c, P1e, and P1g plectin isoforms. The predominant plectin isoform associated with plasmalemmal AQP4 aggregates was P1c, which also affected the mobility of astrocytes most prominently. In the absence of plectin, the collective migration of astrocytes was impaired and the dynamics of cytoplasmic volume changes in peripheral cell regions decreased. Plectin's abundance on the plasma membrane surface and its release from cells were increased in the GBM cell lines. CONCLUSIONS Plectin affects cellular properties that contribute to the pathology of GBM. The observed increase in both cell surface and released plectin levels represents a potential biomarker and therapeutic target in the diagnostics and treatment of GBMs.
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Affiliation(s)
- Maja Žugec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Borut Furlani
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Maria J Castañon
- Max Perutz Laboratories, Department of Biochemistry and Cell Biology, University of Vienna, Vienna, Austria
| | - Boštjan Rituper
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Irmgard Fischer
- Max Perutz Laboratories, Department of Biochemistry and Cell Biology, University of Vienna, Vienna, Austria
| | - Giuseppe Broggi
- Department of Medical and Surgical Sciences and Advanced Technologies "G.F. Ingrassia", University of Catania, Catania, Italy
| | - Rosario Caltabiano
- Department of Medical and Surgical Sciences and Advanced Technologies "G.F. Ingrassia", University of Catania, Catania, Italy
| | - Giuseppe M V Barbagallo
- Department of Medical and Surgical Sciences and Advanced Technologies "G.F. Ingrassia", University of Catania, Catania, Italy
| | - Michelino Di Rosa
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Daniele Tibullo
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Rosalba Parenti
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Nunzio Vicario
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Saša Simčič
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Victorio Martin Pozo Devoto
- International Clinical Research Center (ICRC), St. Anne's University Hospital in Brno, 625 00, Brno, Czech Republic
- Department of Histology and Embryology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Gorazd B Stokin
- Institute for Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czech Republic
- Department of Neurology, Gloucestershire Royal Hospital, Gloucestershire NHS Foundation Trust, Gloucester, UK
- Celica Biomedical, Ljubljana, Slovenia
| | - Gerhard Wiche
- Max Perutz Laboratories, Department of Biochemistry and Cell Biology, University of Vienna, Vienna, Austria
- Celica Biomedical, Ljubljana, Slovenia
| | - Jernej Jorgačevski
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- Celica Biomedical, Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- Celica Biomedical, Ljubljana, Slovenia
| | - Maja Potokar
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
- Celica Biomedical, Ljubljana, Slovenia.
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4
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Freitas-Andrade M, Comin CH, Van Dyken P, Ouellette J, Raman-Nair J, Blakeley N, Liu QY, Leclerc S, Pan Y, Liu Z, Carrier M, Thakur K, Savard A, Rurak GM, Tremblay MÈ, Salmaso N, da F Costa L, Coppola G, Lacoste B. Astroglial Hmgb1 regulates postnatal astrocyte morphogenesis and cerebrovascular maturation. Nat Commun 2023; 14:4965. [PMID: 37587100 PMCID: PMC10432480 DOI: 10.1038/s41467-023-40682-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 07/31/2023] [Indexed: 08/18/2023] Open
Abstract
Astrocytes are intimately linked with brain blood vessels, an essential relationship for neuronal function. However, astroglial factors driving these physical and functional associations during postnatal brain development have yet to be identified. By characterizing structural and transcriptional changes in mouse cortical astrocytes during the first two postnatal weeks, we find that high-mobility group box 1 (Hmgb1), normally upregulated with injury and involved in adult cerebrovascular repair, is highly expressed in astrocytes at birth and then decreases rapidly. Astrocyte-selective ablation of Hmgb1 at birth affects astrocyte morphology and endfoot placement, alters distribution of endfoot proteins connexin43 and aquaporin-4, induces transcriptional changes in astrocytes related to cytoskeleton remodeling, and profoundly disrupts endothelial ultrastructure. While lack of astroglial Hmgb1 does not affect the blood-brain barrier or angiogenesis postnatally, it impairs neurovascular coupling and behavior in adult mice. These findings identify astroglial Hmgb1 as an important player in postnatal gliovascular maturation.
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Affiliation(s)
| | - Cesar H Comin
- Federal University of São Carlos, Department of Computer Science, São Carlos, Brazil
| | - Peter Van Dyken
- Cellular & Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Julie Ouellette
- Neuroscience Program, The Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Cellular & Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Joanna Raman-Nair
- Neuroscience Program, The Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Cellular & Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Nicole Blakeley
- Neuroscience Program, The Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Cellular & Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Qing Yan Liu
- National Research Council of Canada, Human Health and Therapeutics, Ottawa, ON, Canada
- Department of Biochemistry Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Sonia Leclerc
- National Research Council of Canada, Human Health and Therapeutics, Ottawa, ON, Canada
| | - Youlian Pan
- Digital Technologies, National Research Council of Canada, Ottawa, ON, Canada
| | - Ziying Liu
- Digital Technologies, National Research Council of Canada, Ottawa, ON, Canada
| | - Micaël Carrier
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Karan Thakur
- Neuroscience Program, The Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Alexandre Savard
- Neuroscience Program, The Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Gareth M Rurak
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Marie-Ève Tremblay
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
| | - Natalina Salmaso
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - Luciano da F Costa
- University of São Paulo, São Carlos Institute of Physics, FCM-USP, São Paulo, Brazil
| | | | - Baptiste Lacoste
- Neuroscience Program, The Ottawa Hospital Research Institute, Ottawa, ON, Canada.
- Cellular & Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.
- University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada.
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5
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O'Neill KM, Saracino E, Barile B, Mennona NJ, Mola MG, Pathak S, Posati T, Zamboni R, Nicchia GP, Benfenati V, Losert W. Decoding Natural Astrocyte Rhythms: Dynamic Actin Waves Result from Environmental Sensing by Primary Rodent Astrocytes. Adv Biol (Weinh) 2023; 7:e2200269. [PMID: 36709481 DOI: 10.1002/adbi.202200269] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/07/2022] [Indexed: 01/30/2023]
Abstract
Astrocytes are key regulators of brain homeostasis, equilibrating ion, water, and neurotransmitter concentrations and maintaining essential conditions for proper cognitive function. Recently, it has been shown that the excitability of the actin cytoskeleton manifests in second-scale dynamic fluctuations and acts as a sensor of chemophysical environmental cues. However, it is not known whether the cytoskeleton is excitable in astrocytes and how the homeostatic function of astrocytes is linked to the dynamics of the cytoskeleton. Here it is shown that homeostatic regulation involves the excitable dynamics of actin in certain subcellular regions of astrocytes, especially near the cell boundary. The results further indicate that actin dynamics concentrate into "hotspot" regions that selectively respond to certain chemophysical stimuli, specifically the homeostatic challenges of ion or water concentration increases. Substrate topography makes the actin dynamics of astrocytes weaker. Super-resolution images demonstrate that surface topography is also associated with the predominant perpendicular alignment of actin filaments near the cell boundary, whereas flat substrates result in an actin cortex mainly parallel to the cell boundary. Additionally, coculture with neurons increases both the probability of actin dynamics and the strength of hotspots. The excitable systems character of actin thus makes astrocytes direct participants in neural cell network dynamics.
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Affiliation(s)
- Kate M O'Neill
- Institute for Physical Science and Technology, University of Maryland, College Park, MD, 20742, USA
| | - Emanuela Saracino
- Institute of Organic Synthesis and Photoreactivity, National Research Council of Italy, 40129, Bologna, Italy
| | - Barbara Barile
- Biosciences, Biotechnology and Environment, University of Bari Aldo Moro, 70125, Bari, Italy
| | - Nicholas J Mennona
- Institute for Physical Science and Technology, University of Maryland, College Park, MD, 20742, USA
- Physics Department, University of Maryland, College Park, MD, 20742, USA
| | - Maria Grazia Mola
- Biosciences, Biotechnology and Environment, University of Bari Aldo Moro, 70125, Bari, Italy
| | - Spandan Pathak
- Institute for Physical Science and Technology, University of Maryland, College Park, MD, 20742, USA
| | - Tamara Posati
- Institute of Organic Synthesis and Photoreactivity, National Research Council of Italy, 40129, Bologna, Italy
| | - Roberto Zamboni
- Institute of Organic Synthesis and Photoreactivity, National Research Council of Italy, 40129, Bologna, Italy
| | - Grazia P Nicchia
- Biosciences, Biotechnology and Environment, University of Bari Aldo Moro, 70125, Bari, Italy
| | - Valentina Benfenati
- Institute of Organic Synthesis and Photoreactivity, National Research Council of Italy, 40129, Bologna, Italy
| | - Wolfgang Losert
- Institute for Physical Science and Technology, University of Maryland, College Park, MD, 20742, USA
- Physics Department, University of Maryland, College Park, MD, 20742, USA
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6
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Yamada K. Multifaceted Roles of Aquaporins in the Pathogenesis of Alzheimer’s Disease. Int J Mol Sci 2023; 24:ijms24076528. [PMID: 37047501 PMCID: PMC10095057 DOI: 10.3390/ijms24076528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 03/29/2023] [Accepted: 03/29/2023] [Indexed: 04/03/2023] Open
Abstract
The central nervous system is highly dependent on water, and disturbances in water homeostasis can have a significant impact on its normal functions. The regulation of water balance is, at least in part, carried out via specialized water channels called aquaporins. In the central nervous system, two major aquaporins (AQPs), AQP1 and AQP4, and their potential involvements have been long implicated in the pathophysiology of many brain disorders such as brain edema and Neuromyelitis optica. In addition to these diseases, there is growing attention to the involvement of AQPs in the removal of waste products in Alzheimer’s disease (AD). This indicates that targeting fluid homeostasis is a novel and attractive approach for AD. This review article aims to summarize recent knowledge on the pathological implications of AQPs in AD, discussing unsolved questions and future prospects.
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Affiliation(s)
- Kaoru Yamada
- Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
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7
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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.
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8
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The Water Transport System in Astrocytes–Aquaporins. Cells 2022; 11:cells11162564. [PMID: 36010640 PMCID: PMC9406552 DOI: 10.3390/cells11162564] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 07/26/2022] [Accepted: 08/08/2022] [Indexed: 11/16/2022] Open
Abstract
Highlights (AQPs) are transmembrane proteins responsible for fast water movement across cell membranes, including those of astrocytes. The expression and subcellular localization of AQPs in astrocytes are highly dynamic under physiological and pathological conditions. Besides their primary function in water homeostasis, AQPs participate in many ancillary functions including glutamate clearance in tripartite synapses and cell migration.
Abstract Astrocytes have distinctive morphological and functional characteristics, and are found throughout the central nervous system. Astrocytes are now known to be far more than just housekeeping cells in the brain. Their functions include contributing to the formation of the blood–brain barrier, physically and metabolically supporting and communicating with neurons, regulating the formation and functions of synapses, and maintaining water homeostasis and the microenvironment in the brain. Aquaporins (AQPs) are transmembrane proteins responsible for fast water movement across cell membranes. Various subtypes of AQPs (AQP1, AQP3, AQP4, AQP5, AQP8 and AQP9) have been reported to be expressed in astrocytes, and the expressions and subcellular localizations of AQPs in astrocytes are highly correlated with both their physiological and pathophysiological functions. This review describes and summarizes the recent advances in our understanding of astrocytes and AQPs in regard to controlling water homeostasis in the brain. Findings regarding the features of different AQP subtypes, such as their expression, subcellular localization, physiological functions, and the pathophysiological roles of astrocytes are presented, with brain edema and glioma serving as two representative AQP-associated pathological conditions. The aim is to provide a better insight into the elaborate “water distribution” system in cells, exemplified by astrocytes, under normal and pathological conditions.
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9
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Neurons Induce Tiled Astrocytes with Branches That Avoid Each Other. Int J Mol Sci 2022; 23:ijms23084161. [PMID: 35456979 PMCID: PMC9028504 DOI: 10.3390/ijms23084161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 04/02/2022] [Accepted: 04/06/2022] [Indexed: 12/10/2022] Open
Abstract
Neurons induce astrocyte branches that approach synapses. Each astrocyte tiles by expanding branches in an exclusive territory, with limited entries for the neighboring astrocyte branches. However, how astrocytes form exclusive territories is not known. For example, the extensive branching of astrocytes may sterically interfere with the penetration of other astrocyte branches. Alternatively, astrocyte branches may actively avoid each other or remove overlapped branches to establish a territory. Here, we show time-lapse imaging of the multi-order branching process of GFP-labeled astrocytes. Astrocyte branches grow in the direction where other astrocyte branches do not exist. Neurons that had just started to grow dendrites were able to induce astrocyte branching and tiling. Upon neuronal loss by glutamate excitotoxicity, astrocytes’ terminal processes retracted and more branches went over other branches. Our results indicate that neurons induce astrocyte branches and make them avoid each other.
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10
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Ries M, Watts H, Mota BC, Lopez MY, Donat CK, Baxan N, Pickering JA, Chau TW, Semmler A, Gurung B, Aleksynas R, Abelleira-Hervas L, Iqbal SJ, Romero-Molina C, Hernandez-Mir G, d’Amati A, Reutelingsperger C, Goldfinger MH, Gentleman SM, Van Leuven F, Solito E, Sastre M. Annexin A1 restores cerebrovascular integrity concomitant with reduced amyloid-β and tau pathology. Brain 2021; 144:1526-1541. [PMID: 34148071 PMCID: PMC8262982 DOI: 10.1093/brain/awab050] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 11/27/2020] [Accepted: 12/09/2020] [Indexed: 12/05/2022] Open
Abstract
Alzheimer's disease, characterized by brain deposits of amyloid-β plaques and neurofibrillary tangles, is also linked to neurovascular dysfunction and blood-brain barrier breakdown, affecting the passage of substances into and out of the brain. We hypothesized that treatment of neurovascular alterations could be beneficial in Alzheimer's disease. Annexin A1 (ANXA1) is a mediator of glucocorticoid anti-inflammatory action that can suppress microglial activation and reduce blood-brain barrier leakage. We have reported recently that treatment with recombinant human ANXA1 (hrANXA1) reduced amyloid-β levels by increased degradation in neuroblastoma cells and phagocytosis by microglia. Here, we show the beneficial effects of hrANXA1 in vivo by restoring efficient blood-brain barrier function and decreasing amyloid-β and tau pathology in 5xFAD mice and Tau-P301L mice. We demonstrate that young 5xFAD mice already suffer cerebrovascular damage, while acute pre-administration of hrANXA1 rescued the vascular defects. Interestingly, the ameliorated blood-brain barrier permeability in young 5xFAD mice by hrANXA1 correlated with reduced brain amyloid-β load, due to increased clearance and degradation of amyloid-β by insulin degrading enzyme (IDE). The systemic anti-inflammatory properties of hrANXA1 were also observed in 5xFAD mice, increasing IL-10 and reducing TNF-α expression. Additionally, the prolonged treatment with hrANXA1 reduced the memory deficits and increased synaptic density in young 5xFAD mice. Similarly, in Tau-P301L mice, acute hrANXA1 administration restored vascular architecture integrity, affecting the distribution of tight junctions, and reduced tau phosphorylation. The combined data support the hypothesis that blood-brain barrier breakdown early in Alzheimer's disease can be restored by hrANXA1 as a potential therapeutic approach.
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Affiliation(s)
- Miriam Ries
- Department of Brain Sciences, Imperial College London, London, UK
| | - Helena Watts
- Department of Brain Sciences, Imperial College London, London, UK
| | - Bibiana C Mota
- Department of Brain Sciences, Imperial College London, London, UK
| | | | | | - Nicoleta Baxan
- Biological Imaging Centre, Imperial College London, London, UK
| | | | - Tsz Wing Chau
- Department of Brain Sciences, Imperial College London, London, UK
| | - Annika Semmler
- Department of Brain Sciences, Imperial College London, London, UK
| | - Brinda Gurung
- Department of Brain Sciences, Imperial College London, London, UK
| | | | | | | | | | | | - Antonio d’Amati
- William Harvey Research Institute, Queen Mary University London SMD, London, UK
| | - Chris Reutelingsperger
- Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | | | | | - Fred Van Leuven
- Experimental Genetics Group-LEGTEGG, Department of Human Genetics, KU Leuven, Leuven, Belgium
| | - Egle Solito
- William Harvey Research Institute, Queen Mary University London SMD, London, UK
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Universitá degli Studi di Napoli “Federico II”, Naples, Italy
| | - Magdalena Sastre
- Department of Brain Sciences, Imperial College London, London, UK
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11
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Kawaguchi K, Park J, Masaki T, Mezaki Y, Ochi S, Matsuura T. Comprehensive gene expression profiling of human astrocytes treated with a hepatic encephalopathy-inducible factor, alpha 1-antichymotripsin. Biochem Biophys Rep 2020; 24:100855. [PMID: 33299931 PMCID: PMC7704407 DOI: 10.1016/j.bbrep.2020.100855] [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: 06/29/2020] [Revised: 09/29/2020] [Accepted: 11/09/2020] [Indexed: 11/22/2022] Open
Abstract
Astrocytes are major glial cells that play a critical role in brain homeostasis. Abnormalities in astrocytic function, such as hepatic encephalopathy (HE) during acute liver failure, can result in brain death following brain edema and the associated astrocyte swelling. Recently, we have identified alpha 1-antichymotripsin (ACT) to be a biomarker candidate for HE. ACT induces astrocyte swelling by upregulating aquaporin 4 (AQP4); however, the causal connection between these proteins is not clear yet. In this study, we utilized a microarray profile to screen the differentially expressed genes (DEGs) in astrocytes treated with ACT. We then performed Gene Ontology, REACTOME, and the comprehensive resource of mammalian protein complexes (CORUM) enrichment analyses of the identified DEGs. The results of these analyses indicated that the DEGs were enriched in pathways activating adenylate cyclase (AC)-coupled G protein-coupled receptors (GPCRs) and therefore were involved in the cyclic adenosine monophosphate (cAMP) signaling. These results indicate that ACT may act as a ligand of Gs-GPCRs and subsequently upregulate cAMP. As cAMP is known to upregulate AQP4 in astrocytes, these results suggest that ACT may upregulate AQP4 by activating AC GPCRs and therefore serve as a therapeutic target for acute HE. The expression of AQP4 is induced by alpha 1-antichymotripsin dependent activation of adenylate cyclase. Combination treatment of alpha 1-antichymotripsin and arginine vasopressin enhance the activation of adenylate cyclase. Alpha 1-antichemotripsin might be a therapeutic target for acute hepatic encephalopathy.
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Affiliation(s)
- Kenji Kawaguchi
- Department of Laboratory Medicine, The Jikei University School of Medicine, Minato-ku, Tokyo, 105-8461, Japan
| | - Jonghyuk Park
- Department of Laboratory Medicine, The Jikei University School of Medicine, Minato-ku, Tokyo, 105-8461, Japan
| | - Takahiro Masaki
- Department of Laboratory Medicine, The Jikei University School of Medicine, Minato-ku, Tokyo, 105-8461, Japan
| | - Yoshihiro Mezaki
- Department of Laboratory Medicine, The Jikei University School of Medicine, Minato-ku, Tokyo, 105-8461, Japan
| | - Sae Ochi
- Department of Laboratory Medicine, The Jikei University School of Medicine, Minato-ku, Tokyo, 105-8461, Japan
| | - Tomokazu Matsuura
- Department of Laboratory Medicine, The Jikei University School of Medicine, Minato-ku, Tokyo, 105-8461, Japan
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12
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Jorgačevski J, Zorec R, Potokar M. Insights into Cell Surface Expression, Supramolecular Organization, and Functions of Aquaporin 4 Isoforms in Astrocytes. Cells 2020; 9:cells9122622. [PMID: 33297299 PMCID: PMC7762321 DOI: 10.3390/cells9122622] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/03/2020] [Accepted: 12/05/2020] [Indexed: 12/13/2022] Open
Abstract
Aquaporin 4 (AQP4) is the most abundant water channel in the central nervous system (CNS). Its expression is confined to non-neuronal glial cells, predominantly to astrocytes that represent a heterogeneous glial cell type in the CNS. The membrane of astrocyte processes, which align brain capillaries and pia, is particularly rich in AQP4. Several isoforms of AQP4 have been described; however, only some (AQP4a (M1), AQP4 c (M23), AQP4e, and AQP4ex) have been identified in the plasma membrane assemblies of astrocytes termed orthogonal arrays of particles (OAPs). Intracellular splicing isoforms (AQP4b, AQP4d, AQP4f, AQP4-Δ4) have been documented, and most of them are postulated to have a role in the cell surface distribution of the plasma membrane isoforms and in the formation of OAPs in murine and human astrocytes. Although OAPs have been proposed to play various roles in the functioning of astrocytes and CNS tissue as a whole, many of these still need to be described. OAPs are studied primarily from the perspective of understanding water permeability regulation through the plasma membrane and of their involvement in cell adhesion and in the dynamics of astrocytic processes. This review describes the cellular distribution of various AQP4 isoforms and their implications in OAP assembly, which is regulated by several intracellular and extracellular proteins.
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Affiliation(s)
- Jernej Jorgačevski
- Laboratory of Neuroendocrinology—Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; (J.J.); (R.Z.)
- Celica Biomedical, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology—Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; (J.J.); (R.Z.)
- Celica Biomedical, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Maja Potokar
- Laboratory of Neuroendocrinology—Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; (J.J.); (R.Z.)
- Celica Biomedical, Tehnološki park 24, 1000 Ljubljana, Slovenia
- Correspondence: ; Tel.: +386-1543-7020; Fax: +386-1543-7036
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13
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Wang SC, Parpura V, Wang YF. Astroglial Regulation of Magnocellular Neuroendocrine Cell Activities in the Supraoptic Nucleus. Neurochem Res 2020; 46:2586-2600. [PMID: 33216313 DOI: 10.1007/s11064-020-03172-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 11/02/2020] [Accepted: 11/09/2020] [Indexed: 01/02/2023]
Abstract
Studies on the interactions between astrocytes and neurons in the hypothalamo-neurohypophysial system have significantly facilitated our understanding of the regulation of neural activities. This has been exemplified in the interactions between astrocytes and magnocellular neuroendocrine cells (MNCs) in the supraoptic nucleus (SON), specifically during osmotic stimulation and lactation. In response to changes in neurochemical environment in the SON, astrocytic morphology and functions change significantly, which further modulates MNC activity and the secretion of vasopressin and oxytocin. In osmotic regulation, short-term dehydration or water overload causes transient retraction or expansion of astrocytic processes, which increases or decreases the activity of SON neurons, respectively. Prolonged osmotic stimulation causes adaptive change in astrocytic plasticity in the SON, which allows osmosensory neurons to reserve osmosensitivity at new levels. During lactation, changes in neurochemical environment cause retraction of astrocytic processes around oxytocin neurons, which increases MNC's ability to secrete oxytocin. During suckling by a baby/pup, astrocytic processes in the mother/dams exhibit alternative retraction and expansion around oxytocin neurons, which mirrors intermittently synchronized activation of oxytocin neurons and the post-excitation inhibition, respectively. The morphological and functional plasticities of astrocytes depend on a series of cellular events involving glial fibrillary acidic protein, aquaporin 4, volume regulated anion channels, transporters and other astrocytic functional molecules. This review further explores mechanisms underlying astroglial regulation of the neuroendocrine neuronal activities in acute processes based on the knowledge from studies on the SON.
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Affiliation(s)
- Stephani C Wang
- Division of Cardiology, Department of Medicine, University of California-Irvine, Irvine, CA, USA
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, 35242, USA.
| | - Yu-Feng Wang
- Department of Physiology School of Basic Medical Sciences, Harbin Medical University, 157 Baojian Road, Nangang, Harbin, 150086, China.
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Lisjak M, Potokar M, Zorec R, Jorgačevski J. Indirect Role of AQP4b and AQP4d Isoforms in Dynamics of Astrocyte Volume and Orthogonal Arrays of Particles. Cells 2020; 9:cells9030735. [PMID: 32192013 PMCID: PMC7140617 DOI: 10.3390/cells9030735] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/10/2020] [Accepted: 03/13/2020] [Indexed: 01/10/2023] Open
Abstract
Water channel aquaporin 4 (AQP4) plays a key role in the regulation of water homeostasis in the central nervous system (CNS). It is predominantly expressed in astrocytes lining blood–brain and blood–liquor boundaries. AQP4a (M1), AQP4c (M23), and AQP4e, present in the plasma membrane, participate in the cell volume regulation of astrocytes. The function of their splicing variants, AQP4b and AQP4d, predicted to be present in the cytoplasm, is unknown. We examined the cellular distribution of AQP4b and AQP4d in primary rat astrocytes and their role in cell volume regulation. The AQP4b and AQP4d isoforms exhibited extensive cytoplasmic localization in early and late endosomes/lysosomes and in the Golgi apparatus. Neither isoform localized to orthogonal arrays of particles (OAPs) in the plasma membrane. The overexpression of AQP4b and AQP4d isoforms in isoosmotic conditions reduced the density of OAPs; in hypoosmotic conditions, they remained absent from OAPs. In hypoosmotic conditions, the AQP4d isoform was significantly redistributed to early endosomes, which correlated with the increased trafficking of AQP4-laden vesicles. The overexpression of AQP4d facilitated the kinetics of cell swelling, without affecting the regulatory volume decrease. Therefore, although they reside in the cytoplasm, AQP4b and AQP4d isoforms may play an indirect role in astrocyte volume changes.
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Affiliation(s)
- Marjeta Lisjak
- Laboratory of Neuroendocrinology–Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; (M.L.); (M.P.); (R.Z.)
| | - Maja Potokar
- Laboratory of Neuroendocrinology–Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; (M.L.); (M.P.); (R.Z.)
- Celica Biomedical, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology–Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; (M.L.); (M.P.); (R.Z.)
- Celica Biomedical, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Jernej Jorgačevski
- Laboratory of Neuroendocrinology–Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; (M.L.); (M.P.); (R.Z.)
- Celica Biomedical, Tehnološki park 24, 1000 Ljubljana, Slovenia
- Correspondence: ; Tel.: +38615437081
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15
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Palazzo C, Abbrescia P, Valente O, Nicchia GP, Banitalebi S, Amiry-Moghaddam M, Trojano M, Frigeri A. Tissue Distribution of the Readthrough Isoform of AQP4 Reveals a Dual Role of AQP4ex Limited to CNS. Int J Mol Sci 2020; 21:ijms21041531. [PMID: 32102323 PMCID: PMC7073200 DOI: 10.3390/ijms21041531] [Citation(s) in RCA: 16] [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: 01/15/2020] [Revised: 02/14/2020] [Accepted: 02/19/2020] [Indexed: 02/06/2023] Open
Abstract
Translational readthrough (TRT) of aquaporin-4 (AQP4) has remarkably expanded the importance of this new post-transcriptional mechanism, as well as the regulation potential of AQP4. The TRT isoform of AQP4, named AQP4ex, is central for both AQP4 polarization and water channel activity in the central nervous system (CNS). Here we evaluate the relevance of the TRT mechanism by analyzing whether AQP4ex is also expressed in peripheral tissues and whether the expression of AQP4ex is necessary for its polarized expression as it occurs in perivascular astrocyte processes. To this purpose, AQP4ex null mice were used, and analysis was performed by immunolocalization and immunoblot. The results demonstrate that AQP4ex is expressed in kidney, stomach, trachea and skeletal muscle with the same localization pattern as the canonical AQP4 isoforms. AQP4ex protein levels vary from 6% to about 13% of the total AQP4 protein levels in peripheral tissues. Immunogold electron microscopy experiments demonstrated the localization of AQP4ex at the astrocytic endfeet, and experiments conducted on AQP4ex null mice CNS confirmed that the expression of AQP4ex is necessary for anchoring of the perivascular AQP4. Without the readthrough isoform, AQP4 assemblies are mis-localized, being uniformly distributed on the astrocyte processes facing the neuropile. No alteration of AQP4 polarization was found in AQP4ex null kidney, stomach, trachea or skeletal muscle, suggesting that AQP4ex does not have a role for proper membrane localization of AQP4 in peripheral tissues. We conclude that a dual role for AQP4ex is limited to the CNS.
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Affiliation(s)
- Claudia Palazzo
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.P.); (O.V.); (M.T.)
| | - Pasqua Abbrescia
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.P.); (O.V.); (M.T.)
| | - Onofrio Valente
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.P.); (O.V.); (M.T.)
| | - Grazia Paola Nicchia
- Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari Aldo Moro, 70125 Bari, Italy;
| | - Shervin Banitalebi
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (S.B.); (M.A.-M.)
| | - Mahmood Amiry-Moghaddam
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; (S.B.); (M.A.-M.)
| | - Maria Trojano
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.P.); (O.V.); (M.T.)
| | - Antonio Frigeri
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, School of Medicine, University of Bari Aldo Moro, 70124 Bari, Italy; (C.P.); (O.V.); (M.T.)
- Correspondence:
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16
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Li D, Liu X, Liu T, Liu H, Tong L, Jia S, Wang YF. Neurochemical regulation of the expression and function of glial fibrillary acidic protein in astrocytes. Glia 2019; 68:878-897. [PMID: 31626364 DOI: 10.1002/glia.23734] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/27/2019] [Accepted: 09/17/2019] [Indexed: 12/30/2022]
Abstract
Glial fibrillary acidic protein (GFAP), a type III intermediate filament, is a marker of mature astrocytes. The expression of GFAP gene is regulated by many transcription factors (TFs), mainly Janus kinase-2/signal transducer and activator of transcription 3 cascade and nuclear factor κ-light-chain-enhancer of activated B cell signaling. GFAP expression is also modulated by protein kinase and other signaling molecules that are elicited by neuronal activity and hormones. Abnormal expression of GFAP proteins occurs in neuroinflammation, neurodegeneration, brain edema-eliciting diseases, traumatic brain injury, psychiatric disorders and others. GFAP, mainly in α-isoform, is the major component of cytoskeleton and the scaffold of astrocytes, which is essential for the maintenance of astrocytic structure and shape. GFAP also has highly morphological plasticity because of its quick changes in assembling and polymerizing states in response to environmental challenges. This plasticity and its corresponding cellular morphological changes endow astrocytes the functions of physical barrier between adjacent neurons and stabilizer of extracellular environment. Moreover, GFAP colocalizes and even molecularly associates with many functional molecules. This feature allows GFAP to function as a platform for direct interactions between different molecules. Last, GFAP involves transportation and localization of other functional proteins and thus serves as a protein transport guide in astrocytes. This guiding role of GFAP involves an elastic retraction and extension cytoskeletal network that couples with GFAP reassembling, transporting, and membrane protein recycling machinery. This paper reviews our current understanding of the expression and functions of GFAP as well as their regulation.
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Affiliation(s)
- Dongyang Li
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Xiaoyu Liu
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Tianming Liu
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Haitao Liu
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Li Tong
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Shuwei Jia
- Department of Physiology, Harbin Medical University, Harbin, China
| | - Yu-Feng Wang
- Department of Physiology, Harbin Medical University, Harbin, China
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Alarcon-Martinez L, Yilmaz-Ozcan S, Yemisci M, Schallek J, Kılıç K, Villafranca-Baughman D, Can A, Di Polo A, Dalkara T. Retinal ischemia induces α-SMA-mediated capillary pericyte contraction coincident with perivascular glycogen depletion. Acta Neuropathol Commun 2019; 7:134. [PMID: 31429795 PMCID: PMC6701129 DOI: 10.1186/s40478-019-0761-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 06/26/2019] [Indexed: 12/21/2022] Open
Abstract
Increasing evidence indicates that pericytes are vulnerable cells, playing pathophysiological roles in various neurodegenerative processes. Microvascular pericytes contract during cerebral and coronary ischemia and do not relax after re-opening of the occluded artery, causing incomplete reperfusion. However, the cellular mechanisms underlying ischemia-induced pericyte contraction, its delayed emergence, and whether it is pharmacologically reversible are unclear. Here, we investigate i) whether ischemia-induced pericyte contractions are mediated by alpha-smooth muscle actin (α-SMA), ii) the sources of calcium rise in ischemic pericytes, and iii) if peri-microvascular glycogen can support pericyte metabolism during ischemia. Thus, we examined pericyte contractility in response to retinal ischemia both in vivo, using adaptive optics scanning light ophthalmoscopy and, ex vivo, using an unbiased stereological approach. We found that microvascular constrictions were associated with increased calcium in pericytes as detected by a genetically encoded calcium indicator (NG2-GCaMP6) or a fluoroprobe (Fluo-4). Knocking down α-SMA expression with RNA interference or fixing F-actin with phalloidin or calcium antagonist amlodipine prevented constrictions, suggesting that constrictions resulted from calcium- and α-SMA-mediated pericyte contractions. Carbenoxolone or a Cx43-selective peptide blocker also reduced calcium rise, consistent with involvement of gap junction-mediated mechanisms in addition to voltage-gated calcium channels. Pericyte calcium increase and capillary constrictions became significant after 1 h of ischemia and were coincident with depletion of peri-microvascular glycogen, suggesting that glucose derived from glycogen granules could support pericyte metabolism and delay ischemia-induced microvascular dysfunction. Indeed, capillary constrictions emerged earlier when glycogen breakdown was pharmacologically inhibited. Constrictions persisted despite recanalization but were reversible with pericyte-relaxant adenosine administered during recanalization. Our study demonstrates that retinal ischemia, a common cause of blindness, induces α-SMA- and calcium-mediated persistent pericyte contraction, which can be delayed by glucose driven from peri-microvascular glycogen. These findings clarify the contractile nature of capillary pericytes and identify a novel metabolic collaboration between peri-microvascular end-feet and pericytes.
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Affiliation(s)
- Luis Alarcon-Martinez
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Sihhiye, 06100, Ankara, Turkey
- Department of Neuroscience and Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Université de Montréal, Montréal, Québec, Canada
| | - Sinem Yilmaz-Ozcan
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Sihhiye, 06100, Ankara, Turkey
| | - Muge Yemisci
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Sihhiye, 06100, Ankara, Turkey.
- Department of Neurology, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Jesse Schallek
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, New York, USA
| | - Kıvılcım Kılıç
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Sihhiye, 06100, Ankara, Turkey
| | - Deborah Villafranca-Baughman
- Department of Neuroscience and Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Université de Montréal, Montréal, Québec, Canada
| | - Alp Can
- Department of Histology and Embryology, School of Medicine, Ankara University, Ankara, Turkey
| | - Adriana Di Polo
- Department of Neuroscience and Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Université de Montréal, Montréal, Québec, Canada
| | - Turgay Dalkara
- Institute of Neurological Sciences and Psychiatry, Hacettepe University, Sihhiye, 06100, Ankara, Turkey.
- Department of Neurology, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
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18
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Amiry-Moghaddam M. AQP4 and the Fate of Gliomas. Cancer Res 2019; 79:2810-2811. [PMID: 31160309 DOI: 10.1158/0008-5472.can-19-1185] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 04/12/2019] [Accepted: 04/16/2019] [Indexed: 11/16/2022]
Abstract
High-grade glioma is the most common primary brain cancer type and is characterized by invasive and fast growth. In a previous issue of Cancer Research, Simone and colleagues show that the two isoforms of the aquaporin-4 (AQP4) water channel may determine the fate of gliomas. Glioma cell lines expressing the M23-AQP4 isoform, which forms large aggregates of orthogonal arrays of particles, shrink and undergo apoptosis, whereas cell lines expressing the tetramer-forming M1-AQP4 isoform display higher activity of matrix metalloproteinases, making them more invasive. This study provides new insight on the role of AQP4 isoforms in the biology of gliomas.See related article by Simone and colleagues; Cancer Res 79(9):2182-94.
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An aquaporin mediates cell shape change required for cellular immunity in the beet armyworm, Spodoptera exigua. Sci Rep 2019; 9:4988. [PMID: 30899076 PMCID: PMC6428837 DOI: 10.1038/s41598-019-41541-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 03/08/2019] [Indexed: 11/08/2022] Open
Abstract
Cellular immunity in insects is accompanied by change in hemocyte shape. This study hypothesizes that cytoskeletal rearrangement is accompanied by transmembrane water transport to change cell volume, thus changing cell shape. A water-transporting pore (=aquaporin:AQP) has been identified in the beet armyworm, Spodoptera exigua. Its expression was detected in all developmental stages and tissues, although its transcription levels were different between biotic and abiotic conditions. Heterologous expression of Se-AQP in Sf9 cells showed that Se-AQP was localized on cell membrane. RNA interference (RNAi) using double-stranded RNA effectively suppressed its transcript levels. Under different ionic concentrations, hemocytes of RNAi-treated larvae did not change cell volume presumably due to malfunction in water transportation. Se-AQP might participate in glycerol transport because up-regulation of hemolymph glycerol titer after rapid cold-hardening was prevented by RNAi treatment against Se-AQP expression. The inhibitory effect of RNAi treatment on change of cell shape significantly impaired cellular immune responses such as phagocytosis and nodule formation upon bacterial challenge. RNAi treatment also significantly interfered with immature development of S. exigua. These results indicate that Se-AQP plays a crucial role in cell shape change that is required for cellular immunity and other physiological processes.
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20
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Simone L, Pisani F, Mola MG, De Bellis M, Merla G, Micale L, Frigeri A, Vescovi AL, Svelto M, Nicchia GP. AQP4 Aggregation State Is a Determinant for Glioma Cell Fate. Cancer Res 2019; 79:2182-2194. [PMID: 30877104 DOI: 10.1158/0008-5472.can-18-2015] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 01/02/2019] [Accepted: 03/11/2019] [Indexed: 11/16/2022]
Abstract
The glial water channel protein aquaporin-4 (AQP4) forms heterotetramers in the plasma membrane made of the M23-AQP4 and M1-AQP4 isoforms. The isoform ratio controls AQP4 aggregation into supramolecular structures called orthogonal arrays of particles (AQP4-OAP). The role of AQP4 aggregation into OAP in malignant gliomas is still unclear. In this study, we demonstrate that AQP4 aggregation/disaggregation into OAP influences the biology of glioma cells. Selective expression of the OAP-forming isoform M23-AQP4 (AQP4-OAP) triggered cell shape changes in glioma cells associated with alterations to the F-actin cytoskeleton that affected apoptosis. By contrast, expression of M1-AQP4 (AQP4-tetramers), which is unable to aggregate into OAP, ameliorated glioma cell invasiveness, improved cell migration, and increased methalloproteinase-9 activity. Two prolines (254 and 296) at the C-terminus tail were shown to be important in mediating the relationship between the actin cytoskeleton and AQP4-OAP and AQP4-tetramers. In conclusion, this study demonstrates that AQP4 aggregation state might be an important determinant in orienting glioma cells to persist or perish. AQP4 disaggregation may potentiate invasiveness potential, whereas AQP4 aggregation may activate the apoptotic path. This study shows a new perspective on the role of AQP4 in brain tumors not necessarily associated with edema formation but with AQP4 aggregation/disaggregation dynamics and their link with the actin cytoskeleton. SIGNIFICANCE: This study demonstrates how AQP4 aggregation influences plasma membrane dynamics to alter cell proliferation, invasiveness, migration, and apoptotic potential in glioma cells.
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Affiliation(s)
- Laura Simone
- Fondazione IRCCS Casa Sollievo della Sofferenza, Cancer Stem Cells Unit, San Giovanni Rotondo, Italy
| | - Francesco Pisani
- Department of Bioscience, Biotechnology and Biopharmaceutics and Centre of Excellence in Comparative Genomics, University of Bari Aldo Moro, Bari, Italy
| | - Maria G Mola
- Department of Bioscience, Biotechnology and Biopharmaceutics and Centre of Excellence in Comparative Genomics, University of Bari Aldo Moro, Bari, Italy
| | - Manuela De Bellis
- Department of Bioscience, Biotechnology and Biopharmaceutics and Centre of Excellence in Comparative Genomics, University of Bari Aldo Moro, Bari, Italy
| | - Giuseppe Merla
- Division of Medical Genetics, Fondazione IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo, Italy
| | - Lucia Micale
- Division of Medical Genetics, Fondazione IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo, Italy
| | - Antonio Frigeri
- School of Medicine, Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari Aldo Moro, Bari, Italy.,Department of Neuroscience, Albert Einstein College of Medicine, Yeshiva University, New York, Bronx, New York
| | - Angelo L Vescovi
- Fondazione IRCCS Casa Sollievo della Sofferenza, Cancer Stem Cells Unit, San Giovanni Rotondo, Italy
| | - Maria Svelto
- Department of Bioscience, Biotechnology and Biopharmaceutics and Centre of Excellence in Comparative Genomics, 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
| | - Grazia P Nicchia
- Department of Bioscience, Biotechnology and Biopharmaceutics and Centre of Excellence in Comparative Genomics, University of Bari Aldo Moro, Bari, Italy. .,Department of Neuroscience, Albert Einstein College of Medicine, Yeshiva University, New York, Bronx, New York
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21
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Pisani F, Simone L, Mola MG, De Bellis M, Mastrapasqua M, Ruggieri M, Trojano M, Nicchia GP, Svelto M, Frigeri A. Host-Cell Type Dependent Features of Recombinant Human Aquaporin-4 Orthogonal Arrays of Particles-New Insights for Structural and Functional Studies. Cells 2019; 8:cells8020119. [PMID: 30717425 PMCID: PMC6406603 DOI: 10.3390/cells8020119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 01/26/2019] [Accepted: 02/01/2019] [Indexed: 11/16/2022] Open
Abstract
The CNS plasma-membrane water channel aquaporin-4 (AQP4) is expressed as two major isoforms able to aggregate into supramolecular assemblies known as ‘orthogonal arrays of particles’ (OAPs). OAP subnanometric features are largely unknown mainly because a method for the expression, isolation, and crystallization of integral human OAPs has not been developed. Here, the human OAP-forming isoform M23-AQP4 was expressed in insect and mammalian cell lines and AQP4 and OAP features evaluated. Native size exclusion chromatography was employed to isolate and analyze authentically folded OAPs, and neuromyelitis optica (NMO)-specific sandwich ELISA was developed to test OAP-integrity. The results demonstrate that in insect cells most AQP4 remains intracellular and unfolded and that OAPs are largely disassembled after the detergent extraction step. In mammalian cells, AQP4 showed regular plasma membrane targeting and OAPs exhibited strong post-extraction stability. Starting from the mammalian cell expression system, we isolated authentically folded OAPs. Together these data suggest a new strategy for expressing and isolating integral recombinant human OAPs and providing new insights into the cell-type dependent OAP-assembly and post-extraction stability, potentially useful to design new approaches for structural and functional studies of OAP and for other plasma membrane proteins organized into supramolecular structures.
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Affiliation(s)
- Francesco Pisani
- Department of Bioscience, Biotechnologies and Biopharmaceutic, Univ. of Bari "Aldo Moro", 70124 Bari, Italy.
| | - Laura Simone
- Fondazione IRCCS Casa Sollievo della Sofferenza, Cancer Stem Cells Unit, 71013 San Giovanni Rotondo (FG), Italy.
| | - Maria Grazia Mola
- Department of Bioscience, Biotechnologies and Biopharmaceutic, Univ. of Bari "Aldo Moro", 70124 Bari, Italy.
| | - Manuela De Bellis
- Department of Bioscience, Biotechnologies and Biopharmaceutic, Univ. of Bari "Aldo Moro", 70124 Bari, Italy.
| | - Maria Mastrapasqua
- School of Medicine, Basic Medical Sciences, Neuroscience and Sense Organs, Univ. of Bari "Aldo Moro", 70124 Bari, Italy.
| | - Maddalena Ruggieri
- School of Medicine, Basic Medical Sciences, Neuroscience and Sense Organs, Univ. of Bari "Aldo Moro", 70124 Bari, Italy.
| | - Maria Trojano
- School of Medicine, Basic Medical Sciences, Neuroscience and Sense Organs, Univ. of Bari "Aldo Moro", 70124 Bari, Italy.
| | - Grazia Paola Nicchia
- Department of Bioscience, Biotechnologies and Biopharmaceutic, Univ. of Bari "Aldo Moro", 70124 Bari, Italy.
| | - Maria Svelto
- Department of Bioscience, Biotechnologies and Biopharmaceutic, Univ. of Bari "Aldo Moro", 70124 Bari, Italy.
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, 70126 Bari, Italy.
| | - Antonio Frigeri
- School of Medicine, Basic Medical Sciences, Neuroscience and Sense Organs, Univ. of Bari "Aldo Moro", 70124 Bari, Italy.
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22
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Tham DKL, Moukhles H. Towards a better understanding of AQP4's role in astrocytic process extension: An Editorial for 'Involvement of aquaporin-4 in laminin-enhanced process formation of mouse astrocytes in 2D culture: Roles of dystroglycan and a-syntrophin in aquaporin-4 expression' on page 495. J Neurochem 2018; 147:436-438. [PMID: 30378126 DOI: 10.1111/jnc.14590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 09/06/2018] [Indexed: 11/30/2022]
Abstract
At the blood-brain-barrier (BBB), blood vessels are surrounded by the endfoot structures formed by astroglial cells. The latter are themselves part of a larger syncytial network of astrocytes connected to each other via a complex web of processes. The water-permeable channel aquaporin-4 (AQP4) is expressed at high concentrations at these endfeet, held in place by the dystrophin glycoprotein complex (DGC), a collection of proteins that act as a bridge linking AQP4 to the laminin-containing basal lamina found in between the blood vessels and the astrocytic endfeet. Although AQP4, supported by the DGC, has well-established roles in facilitating certain neurological processes, and in mediating the removal of excess water from the brain in certain disease states, relatively few studies have looked at the importance of these components in the regulation of the extension of the processes that are so characteristic of astrocytes. In this Editorial Highlight, we discuss an article by Sato et al., published in this issue of the Journal of Neurochemistry, which attempts to address this question.
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Affiliation(s)
- Daniel Kai Long Tham
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Hakima Moukhles
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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23
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Schiweck J, Eickholt BJ, Murk K. Important Shapeshifter: Mechanisms Allowing Astrocytes to Respond to the Changing Nervous System During Development, Injury and Disease. Front Cell Neurosci 2018; 12:261. [PMID: 30186118 PMCID: PMC6111612 DOI: 10.3389/fncel.2018.00261] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 07/31/2018] [Indexed: 12/30/2022] Open
Abstract
Astrocytes are the most prevalent glial cells in the brain. Historically considered as “merely supporting” neurons, recent research has shown that astrocytes actively participate in a large variety of central nervous system (CNS) functions including synaptogenesis, neuronal transmission and synaptic plasticity. During disease and injury, astrocytes efficiently protect neurons by various means, notably by sealing them off from neurotoxic factors and repairing the blood-brain barrier. Their ramified morphology allows them to perform diverse tasks by interacting with synapses, blood vessels and other glial cells. In this review article, we provide an overview of how astrocytes acquire their complex morphology during development. We then move from the developing to the mature brain, and review current research on perisynaptic astrocytic processes, with a particular focus on how astrocytes engage synapses and modulate their formation and activity. Comprehensive changes have been reported in astrocyte cell shape in many CNS pathologies. Factors influencing these morphological changes are summarized in the context of brain pathologies, such as traumatic injury and degenerative conditions. We provide insight into the molecular, cellular and cytoskeletal machinery behind these shape changes which drive the dynamic remodeling in astrocyte morphology during injury and the development of pathologies.
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Affiliation(s)
- Juliane Schiweck
- Institute for Biochemistry, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Britta J Eickholt
- Institute for Biochemistry, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Kai Murk
- Institute for Biochemistry, Charité Universitätsmedizin Berlin, Berlin, Germany
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24
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Ishii T, Warabi E, Mann GE. Circadian control of p75 neurotrophin receptor leads to alternate activation of Nrf2 and c-Rel to reset energy metabolism in astrocytes via brain-derived neurotrophic factor. Free Radic Biol Med 2018; 119:34-44. [PMID: 29374533 DOI: 10.1016/j.freeradbiomed.2018.01.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 01/17/2018] [Accepted: 01/22/2018] [Indexed: 12/13/2022]
Abstract
Circadian clock genes regulate energy metabolism partly through neurotrophins in the body. The low affinity neurotrophin receptor p75NTR is a clock component directly regulated by the transcriptional factor Clock:Bmal1 complex. Brain-derived neurotrophic factor (BDNF) is expressed in the brain and plays a key role in coordinating metabolic interactions between neurons and astrocytes. BDNF transduces signals through TrkB and p75NTR receptors. This review highlights a novel molecular mechanism by which BDNF via circadian control of p75NTR leads to daily resetting of glucose and glycogen metabolism in brain astrocytes to accommodate their functional interaction with neurons. Astrocytes store glycogen as an energy reservoir to provide active neurons with the glycolytic metabolite lactate. Astrocytes predominantly express the truncated receptor TrkB.T1 which lacks an intracellular receptor tyrosine kinase domain. TrkB.T1 retains the capacity to regulate cell morphology through regulation of Rho GTPases. In contrast, p75NTR mediates generation of the bioactive lipid ceramide upon stimulation with BDNF and inhibits PKA activation. As ceramide directly activates PKCζ, we discuss the importance of the TrkB.T1-p75NTR-ceramide-PKCζ signaling axis in the stimulation of glycogen and lipid synthesis and activation of RhoA. Ceramide-PKCζ-casein kinase 2 signaling activates Nrf2 to support oxidative phosphorylation via upregulation of antioxidant enzymes. In the absence of p75NTR, TrkB.T1 functionally interacts with adenosine A2AR and dopamine D1R receptors to enhance cAMP-PKA signaling and activate Rac1 and NF-κB c-Rel, favoring glycogen hydrolysis, gluconeogenesis and aerobic glycolysis. Thus, diurnal changes in p75NTR levels in astrocytes resets energy metabolism via BDNF to accommodate their metabolic interaction with neurons.
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Affiliation(s)
- Tetsuro Ishii
- School of Medicine, University of Tsukuba, Tsukuba Ibaraki 305-0863, Japan.
| | - Eiji Warabi
- School of Medicine, University of Tsukuba, Tsukuba Ibaraki 305-0863, Japan
| | - Giovanni E Mann
- School of Cardiovascular Medicine and Sciences, King's British Heart Foundation Centre of Excellence, Faculty of Life Sciences and Medicine, King's College London, 150 Stamford Street, London SE1 9NH, UK
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25
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Horner A, Siligan C, Cornean A, Pohl P. Positively charged residues at the channel mouth boost single-file water flow. Faraday Discuss 2018; 209:55-65. [PMID: 29972179 PMCID: PMC6161257 DOI: 10.1039/c8fd00050f] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Positively charged residues in the vicinity of the channel entrance or exit accelerate single-file water flow.
Water molecules lose two of their four bulk neighbours when entering single-file channels. This process may be sensitive to the presence of positive and negative charges at the channel mouth, since the costs for dehydrating cations and anions differ by a large margin. However, it is not known whether entrance charges affect the single channel water permeability (pf). So far, pf is only known to be governed by H-bond formation between permeating water molecules and wall-lining residues. Here we compare the pf values of five different aquaporin species (AQP1, AQPZ, AQP4 wild type, and two phosphorylation mimicking AQP4 mutants) that offer the same number of hydrogen bond donating and receiving residues in their single-file region but display different entrance charges. The pf measurements were performed with reconstituted lipid vesicles. We assessed (i) the osmotically induced vesicle deflation from the light scattering intensity in a stopped-flow device and (ii) the aquaporin abundance by fluorescence correlation spectroscopy. Substitution of serine at positions 111 and 180 in AQP4 for aspartic acid showed only a marginal effect on pf, suggesting that negative entrance charges are of minor importance. In contrast, the total number of positively charged amino acid side chains at entrances and exits correlates with pf: a total of three, four and seven charges of AQP4, AQPZ, and AQP1 translate into pf values of 1.1, 1.8, and 3.2 × 10–13 cm3 s–1, respectively. Thus, positive interfacial charges boost the pf value of AQP1 to three times the value of AQP4. Nevertheless, the number of hydrogen bond donating and receiving residues in the single-file region remains the major determinant of pf. Their effect on pf may be a hundredfold larger than that of interfacial charges.
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Affiliation(s)
- Andreas Horner
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstr. 40, 4020 Linz, Austria.
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26
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AQP4e-Based Orthogonal Arrays Regulate Rapid Cell Volume Changes in Astrocytes. J Neurosci 2017; 37:10748-10756. [PMID: 28978666 DOI: 10.1523/jneurosci.0776-17.2017] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 07/31/2017] [Accepted: 09/23/2017] [Indexed: 01/28/2023] Open
Abstract
Water channel aquaporin 4 (AQP4) plays a key role in the regulation of water homeostasis in the brain. It is predominantly expressed in astrocytes at the blood-brain and blood-liquor interfaces. Although several AQP4 isoforms have been identified in the mammalian brain, two, AQP4a (M1) and AQP4c (M23), have been confirmed to cluster into plasma membrane supramolecular structures, termed orthogonal arrays of particles (OAPs) and to enhance water transport through the plasma membrane. However, the role of the newly described water-conductive mammalian isoform AQP4e is unknown. Here, the dynamics of AQP4e aggregation into OAPs and its role in the regulation of astrocyte water homeostasis have been studied. Using super-resolution structured illumination, atomic force, and confocal microscopies, the results revealed that, in female rat astrocytes, AQP4e isoform colocalizes with OAPs, affecting its structural dynamics. In hypoosmotic conditions, which elicit cell edema, OAP formation was considerably enhanced by overexpressed AQP4e. Moreover, the kinetics of the cell swelling and of the regulatory volume decrease was faster in astrocytes overexpressing AQP4e compared with untransfected controls. Furthermore, the increase in maximal cell volume elicited by hypoosmotic stimulation was significantly smaller in AQP4e-overexpressing astrocytes. For the first time, this study demonstrates an active role of AQP4e in the regulation of OAP structural dynamics and in water homeostasis.SIGNIFICANCE STATEMENT Water channel aquaporin 4 (AQP4) plays a key role in the regulation of water homeostasis in the brain. To date, only AQP4a and AQP4c isoforms have been confirmed to enhance water transport through plasmalemma and to cluster into orthogonal arrays of particles (OAPs). We here studied the dynamics, aggregation, and role in the regulation of astrocyte water homeostasis of the newly described water-conductive mammalian isoform AQP4e. Our main findings are as follows: brain edema mimicking hypoosmotic conditions stimulates the formation of new OAPs with larger diameters, due to the incorporation of additional cytoplasmic AQP4 channels and the redistribution of AQP4 channels of the existing OAPs; and AQP4e affects the dynamics of cell swelling and regulatory volume decrease in astrocytes exposed to hypoosmotic conditions.
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27
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De Bellis M, Pisani F, Mola MG, Rosito S, Simone L, Buccoliero C, Trojano M, Nicchia GP, Svelto M, Frigeri A. Translational readthrough generates new astrocyte AQP4 isoforms that modulate supramolecular clustering, glial endfeet localization, and water transport. Glia 2017; 65:790-803. [PMID: 28206694 DOI: 10.1002/glia.23126] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 01/02/2017] [Accepted: 01/25/2017] [Indexed: 11/10/2022]
Abstract
Regulation of water homeostasis is a central feature of central nervous system pathophysiology. In this context, several lines of evidence suggest a crucial role for the water channel aquaporin-4 (AQP4) and its plasma membrane supramolecular organization as the key element. Here, we demonstrate the expression in tissues of additional isoforms of AQP4 characterized by a C-terminal extension generated by programmed translational readthrough. These extended isoforms (AQP4ex) display a perivascular polarization and expression in dystrophin-dependent pools. AQP4ex reduces supramolecular clustering tendency and allows AQP4 interactions with syntrophin. Furthermore, site-directed mutagenesis of two serines in the extended C-terminus of AQP4ex showed potential regulation of water permeability by phosphorylation. Finally, AQP4ex expression can be positively modulated by gentamicin treatment, demonstrating the possibility of regulating the AQP4 translational readthrough frequency. This novel regulatory mechanism could have important pathophysiological implications for conditions in which alternations have been reported in AQP4 structure.
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Affiliation(s)
- Manuela De Bellis
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy
| | - Francesco Pisani
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy
| | - Maria Grazia Mola
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy
| | - Stefania Rosito
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy
| | - Laura Simone
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy.,IRCCS "Casa Sollievo della Sofferenza", Research Hospital, San Giovanni Rotondo, Foggia, Italy
| | - Cinzia Buccoliero
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy
| | - Maria Trojano
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, Bari, Italy
| | - Grazia Paola Nicchia
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy.,Dominick P. Purpura Department of Neuroscience, 840 Kennedy Center, Bronx, New York
| | - Maria Svelto
- Department of Bioscience, Biotechnologies and Biopharmaceutic and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro", Bari, Italy
| | - Antonio Frigeri
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, Bari, Italy.,Dominick P. Purpura Department of Neuroscience, 840 Kennedy Center, Bronx, New York
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28
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Posati T, Pistone A, Saracino E, Formaggio F, Mola MG, Troni E, Sagnella A, Nocchetti M, Barbalinardo M, Valle F, Bonetti S, Caprini M, Nicchia GP, Zamboni R, Muccini M, Benfenati V. A Nanoscale Interface Promoting Molecular and Functional Differentiation of Neural Cells. Sci Rep 2016; 6:31226. [PMID: 27503424 PMCID: PMC4977496 DOI: 10.1038/srep31226] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 07/04/2016] [Indexed: 12/11/2022] Open
Abstract
Potassium channels and aquaporins expressed by astrocytes are key players in the maintenance of cerebral homeostasis and in brain pathophysiologies. One major challenge in the study of astrocyte membrane channels in vitro, is that their expression pattern does not resemble the one observed in vivo. Nanostructured interfaces represent a significant resource to control the cellular behaviour and functionalities at micro and nanoscale as well as to generate novel and more reliable models to study astrocytes in vitro. However, the potential of nanotechnologies in the manipulation of astrocytes ion channels and aquaporins has never been previously reported. Hydrotalcite-like compounds (HTlc) are layered materials with increasing potential as biocompatible nanoscale interface. Here, we evaluate the effect of the interaction of HTlc nanoparticles films with primary rat neocortical astrocytes. We show that HTlc films are biocompatible and do not promote gliotic reaction, while favouring astrocytes differentiation by induction of F-actin fibre alignment and vinculin polarization. Western Blot, Immunofluorescence and patch-clamp revealed that differentiation was accompanied by molecular and functional up-regulation of both inward rectifying potassium channel Kir 4.1 and aquaporin 4, AQP4. The reported results pave the way to engineering novel in vitro models to study astrocytes in a in vivo like condition.
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Affiliation(s)
- Tamara Posati
- Consiglio Nazionale delle Ricerche (CNR), Istituto per lo Sintesi Organica e la Fotoreattività (ISOF), via Gobetti, 101, 40129, Bologna, Italy
| | - Assunta Pistone
- Consiglio Nazionale delle Ricerche (CNR), Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), via Gobetti, 101, 40129, Bologna, Italy
| | - Emanuela Saracino
- Consiglio Nazionale delle Ricerche (CNR), Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), via Gobetti, 101, 40129, Bologna, Italy
| | - Francesco Formaggio
- Consiglio Nazionale delle Ricerche (CNR), Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), via Gobetti, 101, 40129, Bologna, Italy
| | - Maria Grazia Mola
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari “Aldo Moro”, Via Amendola 165/A, 70126, Bari, Italy
| | - Elisabetta Troni
- Consiglio Nazionale delle Ricerche (CNR), Istituto per lo Sintesi Organica e la Fotoreattività (ISOF), via Gobetti, 101, 40129, Bologna, Italy
| | - Anna Sagnella
- Laboratorio di Micro e Submicro Tecnologie abilitanti dell’Emilia-Romagna (MIST E-R), Via P. Gobetti 101, I-40129 Bologna, Italy
| | - Morena Nocchetti
- Dipartimento di Scienze Farmaceutiche, University of Perugia, Via del Liceo 1, 06123, Perugia, Italy
| | - Marianna Barbalinardo
- Consiglio Nazionale delle Ricerche (CNR), Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), via Gobetti, 101, 40129, Bologna, Italy
| | - Francesco Valle
- Consiglio Nazionale delle Ricerche (CNR), Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), via Gobetti, 101, 40129, Bologna, Italy
| | - Simone Bonetti
- Consiglio Nazionale delle Ricerche (CNR), Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), via Gobetti, 101, 40129, Bologna, Italy
| | - Marco Caprini
- Department of Pharmacy and Biotechnology, via S. Donato 19/2, University of Bologna, 40127 Bologna, Italy
| | - Grazia Paola Nicchia
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari “Aldo Moro”, Via Amendola 165/A, 70126, Bari, Italy
| | - Roberto Zamboni
- Consiglio Nazionale delle Ricerche (CNR), Istituto per lo Sintesi Organica e la Fotoreattività (ISOF), via Gobetti, 101, 40129, Bologna, Italy
| | - Michele Muccini
- Consiglio Nazionale delle Ricerche (CNR), Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), via Gobetti, 101, 40129, Bologna, Italy
| | - Valentina Benfenati
- Consiglio Nazionale delle Ricerche (CNR), Istituto per lo Sintesi Organica e la Fotoreattività (ISOF), via Gobetti, 101, 40129, Bologna, Italy
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29
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Astrocyte Aquaporin Dynamics in Health and Disease. Int J Mol Sci 2016; 17:ijms17071121. [PMID: 27420057 PMCID: PMC4964496 DOI: 10.3390/ijms17071121] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 07/07/2016] [Accepted: 07/07/2016] [Indexed: 02/01/2023] Open
Abstract
The family of aquaporins (AQPs), membrane water channels, consists of diverse types of proteins that are mainly permeable to water; some are also permeable to small solutes, such as glycerol and urea. They have been identified in a wide range of organisms, from microbes to vertebrates and plants, and are expressed in various tissues. Here, we focus on AQP types and their isoforms in astrocytes, a major glial cell type in the central nervous system (CNS). Astrocytes have anatomical contact with the microvasculature, pia, and neurons. Of the many roles that astrocytes have in the CNS, they are key in maintaining water homeostasis. The processes involved in this regulation have been investigated intensively, in particular regulation of the permeability and expression patterns of different AQP types in astrocytes. Three aquaporin types have been described in astrocytes: aquaporins AQP1 and AQP4 and aquaglyceroporin AQP9. The aim here is to review their isoforms, subcellular localization, permeability regulation, and expression patterns in the CNS. In the human CNS, AQP4 is expressed in normal physiological and pathological conditions, but astrocytic expression of AQP1 and AQP9 is mainly associated with a pathological state.
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Astrocytic GAP43 Induced by the TLR4/NF-κB/STAT3 Axis Attenuates Astrogliosis-Mediated Microglial Activation and Neurotoxicity. J Neurosci 2016; 36:2027-43. [PMID: 26865625 DOI: 10.1523/jneurosci.3457-15.2016] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Growth-associated protein 43 (GAP43), a protein kinase C (PKC)-activated phosphoprotein, is often implicated in axonal plasticity and regeneration. In this study, we found that GAP43 can be induced by the endotoxin lipopolysaccharide (LPS) in rat brain astrocytes both in vivo and in vitro. The LPS-induced astrocytic GAP43 expression was mediated by Toll-like receptor 4 and nuclear factor-κB (NF-κB)- and interleukin-6/signal transducer and activator of transcription 3 (STAT3)-dependent transcriptional activation. The overexpression of the PKC phosphorylation-mimicking GAP43(S41D) (constitutive active GAP43) in astrocytes mimicked LPS-induced process arborization and elongation, while application of a NF-κB inhibitory peptide TAT-NBD or GAP43(S41A) (dominant-negative GAP43) or knockdown of GAP43 all inhibited astrogliosis responses. Moreover, GAP43 knockdown aggravated astrogliosis-induced microglial activation and expression of proinflammatory cytokines. We also show that astrogliosis-conditioned medium from GAP43 knock-down astrocytes inhibited GAP43 phosphorylation and axonal growth, and increased neuronal damage in cultured rat cortical neurons. These proneurotoxic effects of astrocytic GAP43 knockdown were accompanied by attenuated glutamate uptake and expression of the glutamate transporter excitatory amino acid transporter 2 (EAAT2) in LPS-treated astrocytes. The regulation of EAAT2 expression involves actin polymerization-dependent activation of the transcriptional coactivator megakaryoblastic leukemia 1 (MKL1), which targets the serum response elements in the promoter of rat Slc1a2 gene encoding EAAT2. In sum, the present study suggests that astrocytic GAP43 mediates glial plasticity during astrogliosis, and provides beneficial effects for neuronal plasticity and survival and attenuation of microglial activation. SIGNIFICANCE STATEMENT Astrogliosis is a complex state in which injury-stimulated astrocytes exert both protective and harmful effects on neuronal survival and plasticity. In this study, we demonstrated for the first time that growth-associated protein 43 (GAP43), a well known growth cone protein that promotes axonal regeneration, can be induced in rat brain astrocytes by the proinflammatory endotoxin lipopolysaccharide via both nuclear factor-κB and signal transducer and activator of transcription 3-mediated transcriptional activation. Importantly, LPS-induced GAP43 mediates plastic changes of astrocytes while attenuating astrogliosis-induced microglial activation and neurotoxicity. Hence, astrocytic GAP43 upregulation may serve to indicate beneficial astrogliosis after CNS injury.
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Di Benedetto B, Malik VA, Begum S, Jablonowski L, Gómez-González GB, Neumann ID, Rupprecht R. Fluoxetine Requires the Endfeet Protein Aquaporin-4 to Enhance Plasticity of Astrocyte Processes. Front Cell Neurosci 2016; 10:8. [PMID: 26869881 PMCID: PMC4735422 DOI: 10.3389/fncel.2016.00008] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Accepted: 01/11/2016] [Indexed: 01/12/2023] Open
Abstract
Morphological alterations in astrocytes are characteristic for post mortem brains of patients affected by major depressive disorder (MDD). Recently, a significant reduction in the coverage of blood vessels (BVs) by aquaporin-4 (AQP-4)-positive astrocyte endfeet has been shown in the prefrontal cortex (PFC) of MDD patients, suggesting that either alterations in the morphology of endfeet or in AQP-4 distribution might be responsible for the disease phenotype or constitute a consequence of its progress. Antidepressant drugs (ADs) regulate the expression of several proteins, including astrocyte-specific ones. Thus, they may target AQP-4 to induce morphological changes in astrocytes and restore their proper shape or relocate AQP-4 to endfeet. Using an animal model of depression, rats selectively bred for high anxiety-like behavior (HAB), we confirmed a reduced coverage of BVs in the adult PFC by AQP-4-immunoreactive (AQP-4-IR) astrocyte processes with respect to non-selected Wistar rats (NAB), thereby validating it for our study. A further evaluation of the morphology of astrocyte in brain slices (ex vivo) and in vitro using an antibody against the astrocyte-specific cytoskeletal protein glial fibrillary acidic protein (GFAP) revealed that HAB astrocytes extended less processes than NAB cells. Furthermore, short-term drug treatment in vitro with the AD fluoxetine (FLX) was sufficient to increase the plasticity of astrocyte processes, enhancing their number in NAB-derived cells and recovering their basal number in HAB-derived cells. This enhanced FLX-dependent plasticity occurred, however, only in the presence of intact AQP-4, as demonstrated by the lack of effect after the downregulation of AQP-4 with RNAi in both NAB and HAB cells. Nonetheless, a similar short-term treatment did neither modulate the coverage of BVs with AQP-4-positive astrocyte endfeet in NAB nor in HAB rats, although dosage and time of treatment were sufficient to fully recover GFAP expression in HAB brains. Thus, we suggest that longer treatment regimes may be needed to properly restore the coverage of BVs or to relocate AQP-4 to astrocyte endfeet. In conclusion, FLX requires AQP-4 to modulate the plasticity of astrocyte processes and this effect might be essential to re-establish a functional glia-vasculature interface necessary for a physiological communication between bloodstream and brain parenchyma.
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Affiliation(s)
- Barbara Di Benedetto
- Laboratory of Neuro-Glia Pharmacology, Department of Psychiatry and Psychotherapy, University of Regensburg Regensburg, Germany
| | - Victoria A Malik
- Laboratory of Neuro-Glia Pharmacology, Department of Psychiatry and Psychotherapy, University of Regensburg Regensburg, Germany
| | - Salina Begum
- Laboratory of Neuro-Glia Pharmacology, Department of Psychiatry and Psychotherapy, University of Regensburg Regensburg, Germany
| | - Lena Jablonowski
- Laboratory of Neuro-Glia Pharmacology, Department of Psychiatry and Psychotherapy, University of Regensburg Regensburg, Germany
| | - Gabriela B Gómez-González
- Laboratory of Neuro-Glia Pharmacology, Department of Psychiatry and Psychotherapy, University of Regensburg Regensburg, Germany
| | - Inga D Neumann
- Department of Neurobiology, University of Regensburg Regensburg, Germany
| | - Rainer Rupprecht
- Laboratory of Neuro-Glia Pharmacology, Department of Psychiatry and Psychotherapy, University of Regensburg Regensburg, Germany
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Karmacharya MB, Kim KH, Kim SY, Chung J, Min BH, Park SR, Choi BH. Low intensity ultrasound inhibits brain oedema formation in rats: potential action on AQP4 membrane localization. Neuropathol Appl Neurobiol 2016; 41:e80-94. [PMID: 25201550 DOI: 10.1111/nan.12182] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 09/03/2014] [Indexed: 12/23/2022]
Abstract
AIMS Brain oedema is a major contributing factor to the morbidity and mortality of a variety of brain disorders. Although there has been considerable progress in our understanding of pathophysiological and molecular mechanisms associated with brain oedema so far, more effective treatment is required and is still awaited. Here we intended to study the effects of low intensity ultrasound (LIUS) on brain oedema. METHODS We prepared the rat hippocampal slice in vitro and acute water intoxication in vivo models of brain oedema. We applied LIUS stimulation in these models and studied the molecular mechanisms of LIUS action on brain oedema. RESULTS We found that LIUS stimulation markedly inhibited the oedema formation in both of these models. LIUS stimulation significantly reduced brain water content and intracranial pressure resulting in increased survival of the rats. Here, we showed that the AQP4 localization was increased in the astrocytic foot processes in the oedematous hippocampal slices, while it was significantly reduced in the LIUS-stimulated hippocampal slices. In the in vivo model too, AQP4 expression was markedly increased in the microvessels of the cerebral cortex and hippocampus after water intoxication but was reduced in the LIUS-stimulated rats. CONCLUSIONS These data show that LIUS has an inhibitory effect on cytotoxic brain oedema and suggest its therapeutic potential to treat brain oedema. We propose that LIUS reduces the AQP4 localization around the astrocytic foot processes thereby decreasing water permeability into the brain tissue.
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Affiliation(s)
| | - Kil Hwan Kim
- Department of Physiology, Inha University College of Medicine, Incheon, Korea
| | - See Yoon Kim
- Department of Physiology, Inha University College of Medicine, Incheon, Korea
| | - Joonho Chung
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Korea
| | - Byoung-Hyun Min
- Department of Orthopaedic Surgery, School of Medicine, Ajou University, Suwon, Korea
| | - So Ra Park
- Department of Physiology, Inha University College of Medicine, Incheon, Korea
| | - Byung Hyune Choi
- Department of Biomedical Sciences, Inha University College of Medicine, Incheon, Korea
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Hubbard JA, Hsu MS, Seldin MM, Binder DK. Expression of the Astrocyte Water Channel Aquaporin-4 in the Mouse Brain. ASN Neuro 2015; 7:7/5/1759091415605486. [PMID: 26489685 PMCID: PMC4623559 DOI: 10.1177/1759091415605486] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Aquaporin-4 (AQP4) is a bidirectional water channel that is found on astrocytes throughout the central nervous system. Expression is particularly high around areas in contact with cerebrospinal fluid, suggesting that AQP4 plays a role in fluid exchange between the cerebrospinal fluid compartments and the brain. Despite its significant role in the brain, the overall spatial and region-specific distribution of AQP4 has yet to be fully characterized. In this study, we used Western blotting and immunohistochemical techniques to characterize AQP4 expression and localization throughout the mouse brain. We observed AQP4 expression throughout the forebrain, subcortical areas, and brainstem. AQP4 protein levels were highest in the cerebellum with lower expression in the cortex and hippocampus. We found that AQP4 immunoreactivity was profuse on glial cells bordering ventricles, blood vessels, and subarachnoid space. Throughout the brain, AQP4 was expressed on astrocytic end-feet surrounding blood vessels but was also heterogeneously expressed in brain tissue parenchyma and neuropil, often with striking laminar specificity. In the cerebellum, we showed that AQP4 colocalized with the proteoglycan brevican, which is synthesized by and expressed on cerebellar astrocytes. Despite the high abundance of AQP4 in the cerebellum, its functional significance has yet to be investigated. Given the known role of AQP4 in synaptic plasticity in the hippocampus, the widespread and region-specific expression pattern of AQP4 suggests involvement not only in fluid balance and ion homeostasis but also local synaptic plasticity and function in distinct brain circuits.
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Affiliation(s)
- Jacqueline A Hubbard
- Center for Glial-Neuronal Interactions, Division of Biomedical Sciences, University of California, Riverside, CA, USA
| | - Mike S Hsu
- Center for Glial-Neuronal Interactions, Division of Biomedical Sciences, University of California, Riverside, CA, USA
| | - Marcus M Seldin
- Division of Cardiology, University of California, Los Angeles, CA, USA
| | - Devin K Binder
- Center for Glial-Neuronal Interactions, Division of Biomedical Sciences, University of California, Riverside, CA, USA
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Mola MG, Sparaneo A, Gargano CD, Spray DC, Svelto M, Frigeri A, Scemes E, Nicchia GP. The speed of swelling kinetics modulates cell volume regulation and calcium signaling in astrocytes: A different point of view on the role of aquaporins. Glia 2015; 64:139-54. [PMID: 26413835 DOI: 10.1002/glia.22921] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 08/14/2015] [Accepted: 09/01/2015] [Indexed: 01/11/2023]
Abstract
Regulatory volume decrease (RVD) is a process by which cells restore their original volume in response to swelling. In this study, we have focused on the role played by two different Aquaporins (AQPs), Aquaporin-4 (AQP4), and Aquaporin-1 (AQP1), in triggering RVD and in mediating calcium signaling in astrocytes under hypotonic stimulus. Using biophysical techniques to measure water flux through the plasma membrane of wild-type (WT) and AQP4 knockout (KO) astrocytes and of an astrocyte cell line (DI TNC1) transfected with AQP4 or AQP1, we here show that AQP-mediated fast swelling kinetics play a key role in triggering and accelerating RVD. Using calcium imaging, we show that AQP-mediated fast swelling kinetics also significantly increases the amplitude of calcium transients inhibited by Gadolinium and Ruthenium Red, two inhibitors of the transient receptor potential vanilloid 4 (TRPV4) channels, and prevented by removing extracellular calcium. Finally, inhibition of TRPV4 or removal of extracellular calcium does not affect RVD. All together our study provides evidence that (1) AQP influenced swelling kinetics is the main trigger for RVD and in mediating calcium signaling after hypotonic stimulus together with TRPV4, and (2) calcium influx from the extracellular space and/or TRPV4 are not essential for RVD to occur in astrocytes.
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Affiliation(s)
- Maria Grazia Mola
- Department of Bioscience, Biotechnology, and Biopharmaceutics, University of Bari "Aldo Moro,", Bari, Italy
| | - Angelo Sparaneo
- Laboratory of Oncology, IRCCS Casa Sollievo Della Sofferenza, San Giovanni Rotondo, Italy
| | - Concetta Domenica Gargano
- Department of Bioscience, Biotechnology, and Biopharmaceutics, University of Bari "Aldo Moro,", Bari, Italy
| | - David C Spray
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Maria Svelto
- Department of Bioscience, Biotechnology, and Biopharmaceutics, University of Bari "Aldo Moro,", Bari, Italy
| | - Antonio Frigeri
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA.,Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari "Aldo Moro,", Bari, Italy
| | - Eliana Scemes
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Grazia Paola Nicchia
- Department of Bioscience, Biotechnology, and Biopharmaceutics, University of Bari "Aldo Moro,", Bari, Italy.,Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, USA
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35
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Camassa LMA, Lunde LK, Hoddevik EH, Stensland M, Boldt HB, De Souza GA, Ottersen OP, Amiry-Moghaddam M. Mechanisms underlying AQP4 accumulation in astrocyte endfeet. Glia 2015; 63:2073-2091. [PMID: 26119521 DOI: 10.1002/glia.22878] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 06/05/2015] [Accepted: 06/05/2015] [Indexed: 11/09/2022]
Abstract
The brain-blood interface holds the key to our understanding of how cerebral blood flow is regulated and how water and solutes are exchanged between blood and brain. The highly specialized astrocytic membranes that enwrap brain microvessels are salient constituents of the brain-blood interface. These endfoot membranes contain a distinct set of molecules that is anchored to the subendothelial basal lamina forming an endfoot-basal lamina junctional complex. Here we explore the mechanisms underpinning the formation of this complex. By use of a tailor made model system we show that endothelial cells promote AQP4 accumulation by exerting an inductive effect through extracellular matrix components such as agrin, as well as through a direct mechanical interaction with the endfoot processes. Through the compounds they secrete, the endothelial cells also increase AQP4 expression. The present data suggest that the highly specialized gliovascular interface is established through inductive processes that include both chemical and mechanical factors. GLIA 2015;63:2073-2091.
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Affiliation(s)
- Laura Maria Azzurra Camassa
- Laboratory of Molecular Neuroscience, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Norway
| | - Lisa K Lunde
- Laboratory of Molecular Neuroscience, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Norway
| | - Eystein H Hoddevik
- Laboratory of Molecular Neuroscience, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Norway
| | - Maria Stensland
- Laboratory of Proteomic Research, Department of Immunology, University of Oslo, Norway
| | - Henning B Boldt
- Laboratory of Molecular Neuroscience, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Norway
| | - Gustavo A De Souza
- Laboratory of Proteomic Research, Department of Immunology, University of Oslo, Norway
| | - Ole P Ottersen
- Laboratory of Molecular Neuroscience, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Norway
| | - Mahmood Amiry-Moghaddam
- Laboratory of Molecular Neuroscience, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Norway
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36
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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.
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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
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37
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Assentoft M, Larsen BR, MacAulay N. Regulation and Function of AQP4 in the Central Nervous System. Neurochem Res 2015; 40:2615-27. [PMID: 25630715 DOI: 10.1007/s11064-015-1519-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 01/08/2015] [Accepted: 01/12/2015] [Indexed: 01/09/2023]
Abstract
Aquaporin 4 (AQP4) is the predominant water channel in the mammalian brain and is mainly expressed in the perivascular glial endfeet at the brain-blood interface. Based on studies on AQP4(-/-) mice, AQP4 has been assigned physiological roles in stimulus-induced K(+) clearance, paravascular fluid flow, and brain edema formation. Conflicting data have been presented on the role of AQP4 in K(+) clearance and associated extracellular space shrinkage and on the stroke-induced alterations of AQP4 expression levels during edema formation, raising questions about the functional importance of AQP4 in these (patho)physiological aspects. Phosphorylation-dependent gating of AQP4 has been proposed as a regulatory mechanism for AQP4-mediated osmotic water transport. This paradigm was, however, recently challenged by experimental evidence and molecular dynamics simulations. Regulatory patterns and physiological roles for AQP4 thus remain to be fully explored.
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Affiliation(s)
- Mette Assentoft
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, Bldg. 12.6, 2200, Copenhagen, Denmark
| | - Brian Roland Larsen
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, Bldg. 12.6, 2200, Copenhagen, Denmark
| | - Nanna MacAulay
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, Bldg. 12.6, 2200, Copenhagen, Denmark.
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38
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Mazzaferri J, Costantino S, Lefrancois S. Analysis of AQP4 trafficking vesicle dynamics using a high-content approach. Biophys J 2014; 105:328-37. [PMID: 23870254 DOI: 10.1016/j.bpj.2013.06.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 06/05/2013] [Accepted: 06/07/2013] [Indexed: 01/11/2023] Open
Abstract
Aquaporin-4 (AQP4) is found on the basolateral plasma membrane of a variety of epithelial cells, and it is widely accepted that microtubules play an important role in protein trafficking to the plasma membrane. In the particular case of polarized trafficking, however, most evidence on the involvement of microtubules has been obtained via biochemistry experiments and single-shot microscopy. These approaches have provided essential information, even though they neglect the dynamical details of microtubule transport. In this work, we present a high-content framework in which time-lapse imaging, and single-particle-tracking algorithms were used to study a large number (∼10(4)) of GFP-AQP4-carrying vesicles on a large number of cells (∼170). By analyzing several descriptors in this large sample of trajectories, we were able to obtain highly statistically significant results. Our results support the hypothesis that AQP4 is transported along microtubules, but to our surprise, this transport is not directed straight to the basolateral plasma membrane. On the contrary, these vesicles move stochastically along microtubules, changing direction repeatedly. We propose that the role of microtubules in the basolateral trafficking of AQP4 is to increase the efficiency, rather than determine the specificity of the target.
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Affiliation(s)
- Javier Mazzaferri
- Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Montréal, Canada
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39
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De Bellis M, Pisani F, Mola MG, Basco D, Catalano F, Nicchia GP, Svelto M, Frigeri A. A novel human aquaporin-4 splice variant exhibits a dominant-negative activity: a new mechanism to regulate water permeability. Mol Biol Cell 2013; 25:470-80. [PMID: 24356448 PMCID: PMC3923639 DOI: 10.1091/mbc.e13-06-0331] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
An alternatively spliced transcript of human AQP4 that lacks exon 4 is identified. In transfected cells, AQP4-Δ4 shows no water transport properties, is retained in the ER, and has a dominant-negative effect on full-length AQP4. In skeletal muscles, AQP4-Δ4 mRNA expression inversely correlates with the level of AQP4 protein in different muscles. Two major isoforms of aquaporin-4 (AQP4) have been described in human tissue. Here we report the identification and functional analysis of an alternatively spliced transcript of human AQP4, AQP4-Δ4, that lacks exon 4. In transfected cells AQP4-Δ4 is mainly retained in the endoplasmic reticulum and shows no water transport properties. When AQP4-Δ4 is transfected into cells stably expressing functional AQP4, the surface expression of the full-length protein is reduced. Furthermore, the water transport activity of the cotransfectants is diminished in comparison to transfectants expressing only AQP4. The observed down-regulation of both the expression and water channel activity of AQP4 is likely to originate from a dominant-negative effect caused by heterodimerization between AQP4 and AQP4-Δ4, which was detected in coimmunoprecipitation studies. In skeletal muscles, AQP4-Δ4 mRNA expression inversely correlates with the level of AQP4 protein and is physiologically associated with different types of skeletal muscles. The expression of AQP4-Δ4 may represent a new regulatory mechanism through which the cell-surface expression and therefore the activity of AQP4 can be physiologically modulated.
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Affiliation(s)
- Manuela De Bellis
- Department of Bioscience, Biotechnologies and Biopharmaceutics and Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro," 70126 Bari, Italy Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland M. Sarcone Hospital, 70038 Terlizzi, Bari, Italy
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Abstract
Aquaporin-4 (AQP4) is one of the most abundant molecules in the brain and is particularly prevalent in astrocytic membranes at the blood-brain and brain-liquor interfaces. While AQP4 has been implicated in a number of pathophysiological processes, its role in brain physiology has remained elusive. Only recently has evidence accumulated to suggest that AQP4 is involved in such diverse functions as regulation of extracellular space volume, potassium buffering, cerebrospinal fluid circulation, interstitial fluid resorption, waste clearance, neuroinflammation, osmosensation, cell migration, and Ca(2+) signaling. AQP4 is also required for normal function of the retina, inner ear, and olfactory system. A review will be provided of the physiological roles of AQP4 in brain and of the growing list of data that emphasize the polarized nature of astrocytes.
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Unraveling aquaporin interaction partners. Biochim Biophys Acta Gen Subj 2013; 1840:1614-23. [PMID: 24252279 DOI: 10.1016/j.bbagen.2013.11.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 11/07/2013] [Accepted: 11/12/2013] [Indexed: 12/18/2022]
Abstract
BACKGROUND Insight into protein-protein interactions (PPIs) is highly desirable in order to understand the physiology of cellular events. This understanding is one of the challenges in biochemistry and molecular biology today, especially for eukaryotic membrane proteins where hurdles of production, purification and structural determination must be passed. SCOPE OF REVIEW We have explored the common strategies used to find medically relevant interaction partners of aquaporins (AQPs). The most frequently used methods to detect direct contact, yeast two-hybrid interaction assay and co-precipitation, are described together with interactions specifically found for the selected targets AQP0, AQP2, AQP4 and AQP5. MAJOR CONCLUSIONS The vast majority of interactions involve the aquaporin C-terminus and the characteristics of the interaction partners are strikingly diverse. While the well-established methods for PPIs are robust, a novel approach like bimolecular fluorescence complementation (BiFC) is attractive for screening many conditions as well as transient interactions. The ultimate goal is structural evaluation of protein complexes in order to get mechanistic insight into how proteins communicate at a molecular level. GENERAL SIGNIFICANCE What we learn from the human aquaporin field in terms of method development and communication between proteins can be of major use for any integral membrane protein of eukaryotic origin. This article is part of a Special Issue entitled Aquaporins.
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42
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Potokar M, Vardjan N, Stenovec M, Gabrijel M, Trkov S, Jorgačevski J, Kreft M, Zorec R. Astrocytic vesicle mobility in health and disease. Int J Mol Sci 2013; 14:11238-58. [PMID: 23712361 PMCID: PMC3709730 DOI: 10.3390/ijms140611238] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 04/26/2013] [Accepted: 05/08/2013] [Indexed: 12/14/2022] Open
Abstract
Astrocytes are no longer considered subservient to neurons, and are, instead, now understood to play an active role in brain signaling. The intercellular communication of astrocytes with neurons and other non-neuronal cells involves the exchange of molecules by exocytotic and endocytotic processes through the trafficking of intracellular vesicles. Recent studies of single vesicle mobility in astrocytes have prompted new views of how astrocytes contribute to information processing in nervous tissue. Here, we review the trafficking of several types of membrane-bound vesicles that are specifically involved in the processes of (i) intercellular communication by gliotransmitters (glutamate, adenosine 5′-triphosphate, atrial natriuretic peptide), (ii) plasma membrane exchange of transporters and receptors (EAAT2, MHC-II), and (iii) the involvement of vesicle mobility carrying aquaporins (AQP4) in water homeostasis. The properties of vesicle traffic in astrocytes are discussed in respect to networking with neighboring cells in physiologic and pathologic conditions, such as amyotrophic lateral sclerosis, multiple sclerosis, and states in which astrocytes contribute to neuroinflammatory conditions.
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Affiliation(s)
- Maja Potokar
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Matjaž Stenovec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Mateja Gabrijel
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Saša Trkov
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Jernej Jorgačevski
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Marko Kreft
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
- Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +386-1543-7020; Fax: +386-1543-7036
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Effects of prednisolone on the dystrophin-associated proteins in the blood-brain barrier and skeletal muscle of dystrophic mdx mice. J Transl Med 2013; 93:592-610. [PMID: 23528847 DOI: 10.1038/labinvest.2013.46] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The mdx mouse, the most widely used animal model of Duchenne muscular dystrophy (DMD), develops a seriously impaired blood-brain barrier (BBB). As glucocorticoids are used clinically to delay the progression of DMD, we evaluated the effects of chronic treatment with α-methyl-prednisolone (PDN) on the expression of structural proteins and markers in the brain and skeletal muscle of the mdx mouse. We analyzed the immunocytochemical and biochemical expression of four BBB markers, including endothelial ZO-1 and occludin, desmin in pericytes, and glial fibrillary acidic protein (GFAP) in glial cells, and the expression of the short dystrophin isoform Dp 71, the dystrophin-associated proteins (DAPs), and aquaporin-4 (AQP4) and α-β dystroglycan (DG) in the brain. We evaluated the BBB integrity of mdx and PDN-treated mdx mice by means of intravascular injection of horseradish peroxidase (HRP). The expression of DAPs was also assessed in gastrocnemius muscles and correlated with utrophin expression, and laminin content was measured in the muscle and brain. PDN treatment induced a significant increase in the mRNA and protein content of the BBB markers; a reduction in the phosphorylation of occludin in the brain and of AQP4/β DG in both tissues; an increase of Dp71 protein content; and an increase of both mRNA and protein levels of the AQP4/α-β DG complex. The latter was associated with enhanced laminin and utrophin in the muscle. The HRP assay demonstrated functional restoration of the BBB in the PDN-treated mdx mice. Specifically, mdx mice showed extensive perivascular labeling due to escape of the marker, while HRP was exclusively intravascular in the PDN-treated mice and the controls. These data illustrate for the first time that PDN reverses the BBB alterations in the mdx mouse and re-establishes the proper expression and phosphorylation of β-DG in both the BBB and skeletal muscle. Further, PDN partially protects against muscle damage. The reduction in AQP4 and occludin phosphorylation, coupled with their anchoring to glial and endothelial membranes in PDN-treated mice, suggests that the drug may target the glial and endothelial cells. Our results suggest a novel mechanism for PDN action on cerebral and muscular function, restoring the link between DAPs and the extracellular matrix, most likely through protein kinase inactivation.
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Potokar M, Stenovec M, Jorgačevski J, Holen T, Kreft M, Ottersen OP, Zorec R. Regulation of AQP4 surface expression via vesicle mobility in astrocytes. Glia 2013; 61:917-28. [DOI: 10.1002/glia.22485] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 01/28/2013] [Indexed: 11/05/2022]
Affiliation(s)
| | | | | | - Torgeir Holen
- Center for Molecular Biology and Neuroscience; University of Oslo; Oslo; Norway
| | | | - Ole Petter Ottersen
- Center for Molecular Biology and Neuroscience; University of Oslo; Oslo; Norway
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Inhibition of aquaporin-1 dependent angiogenesis impairs tumour growth in a mouse model of melanoma. J Mol Med (Berl) 2012. [DOI: 10.1007/s00109-012-0977-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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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]
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The cardioprotection of simvastatin in reperfused swine hearts relates to the inhibition of myocardial edema by modulating aquaporins via the PKA pathway. Int J Cardiol 2012; 167:2657-66. [PMID: 22819122 DOI: 10.1016/j.ijcard.2012.06.121] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 04/30/2012] [Accepted: 06/24/2012] [Indexed: 01/13/2023]
Abstract
BACKGROUND AND OBJECTIVE Myocardial edema plays a role in myocardial no-reflow and infarction during ischemia and reperfusion. The effects of statins against no-reflow and infarction may relate to the inhibition of myocardial edema. The current study investigated the role of protein kinase A (PKA) in statin-reduced myocardial edema in reperfused swine hearts. METHODS AND RESULTS Minipigs were treated with simvastatin (SIM, 2mg/kg), SIM+H-89 (a PKA inhibitor, 1.0 μg/kg/min), or H-89 alone 1h before 90-min ischemia and 3-h reperfusion or sham operation. Ischemia or ischemia-reperfusion induced severe myocardial edema, PKA activation, and up-regulation of aquaporin-1, -4, -8, and -9 in the reflow and no-reflow myocardium. SIM pretreatment reduced the sizes of no-reflow and infarct areas by 18.5% and 11.1% (P<0.01), decreased water content in the left ventricle, reflow and no-reflow myocardium by 1.4%, 5.3%, and 4.3% (P<0.05), inhibited cardiomyocytes swelling in the reflow and no-reflow areas by 19.8% and 13.1% (P<0.01), suppressed mitochondrial water accumulation in the reflow and no-reflow areas by 49.0% and 35.9% (P<0.01), increased PKA activity (P<0.01), and blocked the up-regulation of aquaporin-1, -4, -8, and -9 in the reflow and no-reflow myocardium. However, these beneficial effects of SIM were partially abolished by inhibiting PKA with H-89. CONCLUSIONS The cardioprotective effects of acute SIM therapy against myocardial no-reflow and infarction relate to the reduction of myocardial edema by suppressing the expression of aquaporin-1, -4, -8, and -9 in a partially PKA-dependent manner.
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Melamud L, Fernández JM, Rivarola V, Di Giusto G, Ford P, Villa A, Capurro C. Neuromyelitis Optica Immunoglobulin G present in sera from neuromyelitis optica patients affects aquaporin-4 expression and water permeability of the astrocyte plasma membrane. J Neurosci Res 2012; 90:1240-8. [DOI: 10.1002/jnr.22822] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 06/06/2011] [Accepted: 10/03/2011] [Indexed: 11/10/2022]
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Duarri A, Lopez de Heredia M, Capdevila-Nortes X, Ridder MC, Montolio M, López-Hernández T, Boor I, Lien CF, Hagemann T, Messing A, Gorecki DC, Scheper GC, Martínez A, Nunes V, van der Knaap MS, Estévez R. Knockdown of MLC1 in primary astrocytes causes cell vacuolation: a MLC disease cell model. Neurobiol Dis 2011; 43:228-38. [PMID: 21440627 DOI: 10.1016/j.nbd.2011.03.015] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 03/07/2011] [Accepted: 03/14/2011] [Indexed: 10/18/2022] Open
Abstract
Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare type of leukodystrophy, in the majority of cases caused by mutations in the MLC1 gene. MRI from MLC patients shows diffuse cerebral white matter signal abnormality and swelling, with evidence of increased water content. Histopathology in a MLC patient shows vacuolation of myelin, which causes the cerebral white matter swelling. MLC1 protein is expressed in astrocytic processes that are part of blood- and cerebrospinal fluid-brain barriers. We aimed to create an astrocyte cell model of MLC disease. The characterization of rat astrocyte cultures revealed MLC1 localization in cell-cell contacts, which contains other proteins described typically in tight and adherent junctions. MLC1 localization in these contacts was demonstrated to depend on the actin cytoskeleton; it was not altered when disrupting the microtubule or the GFAP networks. In human tissues, MLC1 and the protein Zonula Occludens 1 (ZO-1), which is linked to the actin cytoskeleton, co-localized by EM immunostaining and were specifically co-immunoprecipitated. To create an MLC cell model, knockdown of MLC1 in primary astrocytes was performed. Reduction of MLC1 expression resulted in the appearance of intracellular vacuoles. This vacuolation was reversed by the co-expression of human MLC1. Re-examination of a human brain biopsy from an MLC patient revealed that vacuoles were also consistently present in astrocytic processes. Thus, vacuolation of astrocytes is also a hallmark of MLC disease.
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Affiliation(s)
- Anna Duarri
- Sección de Fisiología, Departamento de Ciencias Fisiológicas II, Universidad de Barcelona, Spain
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Zelenina M. Regulation of brain aquaporins. Neurochem Int 2010; 57:468-88. [DOI: 10.1016/j.neuint.2010.03.022] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 03/21/2010] [Accepted: 03/31/2010] [Indexed: 01/27/2023]
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