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Yang J, Cao C, Liu J, Liu Y, Lu J, Yu H, Li X, Wu J, Yu Z, Li H, Chen G. Dystrophin 71 deficiency causes impaired aquaporin-4 polarization contributing to glymphatic dysfunction and brain edema in cerebral ischemia. Neurobiol Dis 2024; 199:106586. [PMID: 38950712 DOI: 10.1016/j.nbd.2024.106586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 06/28/2024] [Accepted: 06/28/2024] [Indexed: 07/03/2024] Open
Abstract
OBJECTIVE The glymphatic system serves as a perivascular pathway that aids in clearing liquid and solute waste from the brain, thereby enhancing neurological function. Disorders in glymphatic drainage contribute to the development of vasogenic edema following cerebral ischemia, although the molecular mechanisms involved remain poorly understood. This study aims to determine whether a deficiency in dystrophin 71 (DP71) leads to aquaporin-4 (AQP4) depolarization, contributing to glymphatic dysfunction in cerebral ischemia and resulting in brain edema. METHODS A mice model of middle cerebral artery occlusion and reperfusion was used. A fluorescence tracer was injected into the cortex and evaluated glymphatic clearance. To investigate the role of DP71 in maintaining AQP4 polarization, an adeno-associated virus with the astrocyte promoter was used to overexpress Dp71. The expression and distribution of DP71 and AQP4 were analyzed using immunoblotting, immunofluorescence, and co-immunoprecipitation techniques. The behavior ability of mice was evaluated by open field test. Open-access transcriptome sequencing data were used to analyze the functional changes of astrocytes after cerebral ischemia. MG132 was used to inhibit the ubiquitin-proteasome system. The ubiquitination of DP71 was detected by immunoblotting and co-immunoprecipitation. RESULTS During the vasogenic edema stage following cerebral ischemia, a decline in the efflux of interstitial fluid tracer was observed. DP71 and AQP4 were co-localized and interacted with each other in the perivascular astrocyte endfeet. After cerebral ischemia, there was a notable reduction in DP71 protein expression, accompanied by AQP4 depolarization and proliferation of reactive astrocytes. Increased DP71 expression restored glymphatic drainage and reduced brain edema. AQP4 depolarization, reactive astrocyte proliferation, and the behavior of mice were improved. After cerebral ischemia, DP71 was degraded by ubiquitination, and MG132 inhibited the decrease of DP71 protein level. CONCLUSION AQP4 depolarization after cerebral ischemia leads to glymphatic clearance disorder and aggravates cerebral edema. DP71 plays a pivotal role in regulating AQP4 polarization and consequently influences glymphatic function. Changes in DP71 expression are associated with the ubiquitin-proteasome system. This study offers a novel perspective on the pathogenesis of brain edema following cerebral ischemia.
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Affiliation(s)
- Jian Yang
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China; Institute of Stroke Research, Soochow University, Suzhou, Jiangsu Province, China
| | - Chang Cao
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China; Institute of Stroke Research, Soochow University, Suzhou, Jiangsu Province, China
| | - Jiale Liu
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China; Institute of Stroke Research, Soochow University, Suzhou, Jiangsu Province, China
| | - Yangyang Liu
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China; Institute of Stroke Research, Soochow University, Suzhou, Jiangsu Province, China
| | - Jinxin Lu
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China; Institute of Stroke Research, Soochow University, Suzhou, Jiangsu Province, China
| | - HaoYun Yu
- Suzhou Medical College, Soochow University, Suzhou, Jiangsu Province, China
| | - Xiang Li
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China; Institute of Stroke Research, Soochow University, Suzhou, Jiangsu Province, China
| | - Jiang Wu
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China; Institute of Stroke Research, Soochow University, Suzhou, Jiangsu Province, China.
| | - Zhengquan Yu
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China; Institute of Stroke Research, Soochow University, Suzhou, Jiangsu Province, China.
| | - Haiying Li
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China; Institute of Stroke Research, Soochow University, Suzhou, Jiangsu Province, China.
| | - Gang Chen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu Province, China; Institute of Stroke Research, Soochow University, Suzhou, Jiangsu Province, China
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2
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Verhaeg M, Adamzek K, van de Vijver D, Putker K, Engelbeen S, Wijnbergen D, Overzier M, Suidgeest E, van der Weerd L, Aartsma‐Rus A, van Putten M. Learning, memory and blood-brain barrier pathology in Duchenne muscular dystrophy mice lacking Dp427, or Dp427 and Dp140. GENES, BRAIN, AND BEHAVIOR 2024; 23:e12895. [PMID: 38837620 PMCID: PMC11151035 DOI: 10.1111/gbb.12895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 03/22/2024] [Accepted: 03/28/2024] [Indexed: 06/07/2024]
Abstract
Duchenne muscular dystrophy is a severe neuromuscular disorder that is caused by mutations in the DMD gene, resulting in a disruption of dystrophin production. Next to dystrophin expression in the muscle, different isoforms of the protein are also expressed in the brain and lack of these isoforms leads to cognitive and behavioral deficits in patients. It remains unclear how the loss of the shorter dystrophin isoform Dp140 affects these processes. Using a variety of behavioral tests, we found that mdx and mdx4cv mice (which lack Dp427 or Dp427 + Dp140, respectively) exhibit similar deficits in working memory, movement patterns and blood-brain barrier integrity. Neither model showed deficits in spatial learning and memory, learning flexibility, anxiety or spontaneous behavior, nor did we observe differences in aquaporin 4 and glial fibrillary acidic protein. These results indicate that in contrast to Dp427, Dp140 does not play a crucial role in processes of learning, memory and spontaneous behavior.
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Affiliation(s)
- Minou Verhaeg
- Department of Human GeneticsLeiden University Medical CenterLeidenThe Netherlands
| | - Kevin Adamzek
- Department of Human GeneticsLeiden University Medical CenterLeidenThe Netherlands
| | - Davy van de Vijver
- Department of Human GeneticsLeiden University Medical CenterLeidenThe Netherlands
| | - Kayleigh Putker
- Department of Human GeneticsLeiden University Medical CenterLeidenThe Netherlands
| | - Sarah Engelbeen
- Department of Human GeneticsLeiden University Medical CenterLeidenThe Netherlands
| | - Daphne Wijnbergen
- Department of Human GeneticsLeiden University Medical CenterLeidenThe Netherlands
| | - Maurice Overzier
- Department of Human GeneticsLeiden University Medical CenterLeidenThe Netherlands
| | - Ernst Suidgeest
- C.J. Gorter MRI Center, Department of RadiologyLeiden University Medical CenterLeidenThe Netherlands
| | - Louise van der Weerd
- Department of Human GeneticsLeiden University Medical CenterLeidenThe Netherlands
- C.J. Gorter MRI Center, Department of RadiologyLeiden University Medical CenterLeidenThe Netherlands
| | | | - Maaike van Putten
- Department of Human GeneticsLeiden University Medical CenterLeidenThe Netherlands
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3
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Yaghoobi Z, Seyed Bagher Nazeri SS, Asadi A, Derafsh E, Talebi Taheri A, Tamtaji Z, Dadgostar E, Rahmati-Dehkordi F, Aschner M, Mirzaei H, Tamtaji OR, Nabavizadeh F. Non-coding RNAs and Aquaporin 4: Their Role in the Pathogenesis of Neurological Disorders. Neurochem Res 2024; 49:583-596. [PMID: 38114727 DOI: 10.1007/s11064-023-04067-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 11/10/2023] [Accepted: 11/14/2023] [Indexed: 12/21/2023]
Abstract
Neurological disorders are a major group of non-communicable diseases affecting quality of life. Non-Coding RNAs (ncRNAs) have an important role in the etiology of neurological disorders. In studies on the genesis of neurological diseases, aquaporin 4 (AQP4) expression and activity have both been linked to ncRNAs. The upregulation or downregulation of several ncRNAs leads to neurological disorder progression by targeting AQP4. The role of ncRNAs and AQP4 in neurological disorders is discussed in this review.
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Affiliation(s)
- Zahra Yaghoobi
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, I.R. of Iran
- Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, I.R. of Iran
| | | | - Amir Asadi
- Psychiatry and Behavioral Sciences Research Center, School of Medicine, Addiction Institute, and Department of Psychiatry, Mazandaran University of Medical Sciences, Sari, Iran
| | - Ehsan Derafsh
- Windsor University School of Medicine, Cayon, St Kitts and Nevis
| | - Abdolkarim Talebi Taheri
- Student Research Committee, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Zeinab Tamtaji
- Student Research Committee, Kashan University of Medical Sciences, Kashan, I.R. of Iran
| | - Ehsan Dadgostar
- Behavioral Sciences Research Center, Isfahan University of Medical Sciences, Isfahan, I.R. of Iran
- Student Research Committee, Isfahan University of Medical Sciences, Isfahan, I.R. of Iran
| | - Fatemeh Rahmati-Dehkordi
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, I.R. of Iran
- Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, I.R. of Iran
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Hamed Mirzaei
- Research Center for Biochemistry and Nutrition in Metabolic Diseases, Kashan University of Medical Sciences, Kashan, I.R. of Iran.
| | - Omid Reza Tamtaji
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, I.R. of Iran.
- Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, I.R. of Iran.
| | - Fatemeh Nabavizadeh
- Electrophysiology Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, I.R. of Iran.
- Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, I.R. of Iran.
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4
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Maki H, Mori-Yoshimura M, Matsuda H, Hashimoto Y, Ota M, Kimura Y, Shigemoto Y, Ishihara N, Kan H, Chiba E, Arizono E, Yoshida S, Takahashi Y, Sato N. Brain Abnormalities in Becker Muscular Dystrophy: Evaluation by Voxel-Based DTI and Morphometric Analysis. AJNR Am J Neuroradiol 2023; 44:1405-1410. [PMID: 37945525 PMCID: PMC10714854 DOI: 10.3174/ajnr.a8041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 09/28/2023] [Indexed: 11/12/2023]
Abstract
BACKGROUND AND PURPOSE Although various neuropsychological problems in Becker muscular dystrophy have attracted attention, there have been few related neuroimaging studies. We investigated brain abnormalities in patients with Becker muscular dystrophy using 3D T1WI and DTI. MATERIALS AND METHODS MR images were obtained for 30 male patients and 30 age-matched healthy male controls. We classified patients into Dp140+ and Dp140- subgroups based on their predicted dystrophin Dp140 isoform expression and performed voxel-based comparisons of gray and white matter volumes and DTI metrics among the patients, patient subgroups, and controls. ROI-based DTI analyses were also performed. RESULTS Significantly decreased fractional anisotropy was observed in the left planum temporale and right superior parietal lobule compared between the Becker muscular dystrophy and control groups. In the Dp140- subgroup, decreased fractional anisotropy was observed in the left planum temporale, but no significant changes were seen in the Dp140+ subgroup. The ROI-based analysis obtained the same results. No significant differences were evident in the gray or white matter volumes or the DTI metrics other than fractional anisotropy between the groups. CONCLUSIONS A DTI metric analysis is useful to detect white-matter microstructural abnormalities in Becker muscular dystrophy that may be affected by the Dp140 isoform expression.
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Affiliation(s)
- Hiroyuki Maki
- From the Department of Radiology (H. Maki, Y.K., Y.S., E.C., E.A., N.S.), National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Madoka Mori-Yoshimura
- Department of Neurology (M.M.-Y., Y.T.), National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Hiroshi Matsuda
- Department of Biofunctional Imaging (H. Matsuda), Fukushima Medical University, Fukushima, Japan
| | - Yasumasa Hashimoto
- Department of Neurology (Y.H.), Kansai Medical University, Osaka, Japan
- Department of Molecular Therapy (Y.H.), National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Miho Ota
- Department of Neuropsychiatry (M.O.), University of Tsukuba, Ibaraki, Japan
| | - Yukio Kimura
- From the Department of Radiology (H. Maki, Y.K., Y.S., E.C., E.A., N.S.), National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yoko Shigemoto
- From the Department of Radiology (H. Maki, Y.K., Y.S., E.C., E.A., N.S.), National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Naoko Ishihara
- Medical Genome Center (N.I., S.Y.), National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Hirohito Kan
- Department of Integrated Health Sciences (H.K.), Nagoya University Graduate School of Medicine, Aichi, Japan
| | - Emiko Chiba
- From the Department of Radiology (H. Maki, Y.K., Y.S., E.C., E.A., N.S.), National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Elly Arizono
- From the Department of Radiology (H. Maki, Y.K., Y.S., E.C., E.A., N.S.), National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Sumiko Yoshida
- Medical Genome Center (N.I., S.Y.), National Center of Neurology and Psychiatry, Tokyo, Japan
- Department of Psychiatric Rehabilitation (S.Y.), National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yuji Takahashi
- Department of Neurology (M.M.-Y., Y.T.), National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Noriko Sato
- From the Department of Radiology (H. Maki, Y.K., Y.S., E.C., E.A., N.S.), National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
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5
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Mucha O, Myszka M, Podkalicka P, Świderska B, Malinowska A, Dulak J, Łoboda A. Proteome Profiling of the Dystrophic mdx Mice Diaphragm. Biomolecules 2023; 13:1648. [PMID: 38002330 PMCID: PMC10669179 DOI: 10.3390/biom13111648] [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: 09/26/2023] [Revised: 11/02/2023] [Accepted: 11/08/2023] [Indexed: 11/26/2023] Open
Abstract
Mdx mice with a spontaneous mutation in exon 23 of the Dmd gene represent the most common model to investigate the pathophysiology of Duchenne muscular dystrophy (DMD). The disease, caused by the lack of functional dystrophin, is characterized by irreversible impairment of muscle functions, with the diaphragm affected earlier and more severely than other skeletal muscles. We applied a label-free (LF) method and the more thorough tandem mass tag (TMT)-based method to analyze differentially expressed proteins in the diaphragm of 6-week-old mdx mice. The comparison of both methods revealed 88 commonly changed proteins. A more in-depth analysis of the TMT-based method showed 953 significantly changed proteins, with 867 increased and 86 decreased in dystrophic animals (q-value < 0.05, fold-change threshold: 1.5). Consequently, several dysregulated processes were demonstrated, including the immune response, fibrosis, translation, and programmed cell death. Interestingly, in the dystrophic diaphragm, we found a significant decrease in the expression of enzymes generating hydrogen sulfide (H2S), suggesting that alterations in the metabolism of this gaseous mediator could modulate DMD progression, which could be a potential target for pharmacological intervention.
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Affiliation(s)
- Olga Mucha
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7 Street, 30-387 Kraków, Poland; (O.M.); (M.M.); (P.P.); (J.D.)
| | - Małgorzata Myszka
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7 Street, 30-387 Kraków, Poland; (O.M.); (M.M.); (P.P.); (J.D.)
- Doctoral School of Exact and Natural Sciences, Łojasiewicza 11 Street, 30-348 Kraków, Poland
| | - Paulina Podkalicka
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7 Street, 30-387 Kraków, Poland; (O.M.); (M.M.); (P.P.); (J.D.)
| | - Bianka Świderska
- Mass Spectrometry Laboratory, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a Street, 02-106 Warsaw, Poland; (B.Ś.); (A.M.)
| | - Agata Malinowska
- Mass Spectrometry Laboratory, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a Street, 02-106 Warsaw, Poland; (B.Ś.); (A.M.)
| | - Józef Dulak
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7 Street, 30-387 Kraków, Poland; (O.M.); (M.M.); (P.P.); (J.D.)
| | - Agnieszka Łoboda
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7 Street, 30-387 Kraków, Poland; (O.M.); (M.M.); (P.P.); (J.D.)
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Garcia TA, Jonak CR, Binder DK. The Role of Aquaporins in Spinal Cord Injury. Cells 2023; 12:1701. [PMID: 37443735 PMCID: PMC10340765 DOI: 10.3390/cells12131701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 06/08/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023] Open
Abstract
Edema formation following traumatic spinal cord injury (SCI) exacerbates secondary injury, and the severity of edema correlates with worse neurological outcome in human patients. To date, there are no effective treatments to directly resolve edema within the spinal cord. The aquaporin-4 (AQP4) water channel is found on plasma membranes of astrocytic endfeet in direct contact with blood vessels, the glia limitans in contact with the cerebrospinal fluid, and ependyma around the central canal. Local expression at these tissue-fluid interfaces allows AQP4 channels to play an important role in the bidirectional regulation of water homeostasis under normal conditions and following trauma. In this review, we consider the available evidence regarding the potential role of AQP4 in edema after SCI. Although more work remains to be carried out, the overall evidence indicates a critical role for AQP4 channels in edema formation and resolution following SCI and the therapeutic potential of AQP4 modulation in edema resolution and functional recovery. Further work to elucidate the expression and subcellular localization of AQP4 during specific phases after SCI will inform the therapeutic modulation of AQP4 for the optimization of histological and neurological outcomes.
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Affiliation(s)
- Terese A. Garcia
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
| | - Carrie R. Jonak
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
| | - Devin K. Binder
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA 92521, USA
- Center for Glial-Neuronal Interactions, University of California, Riverside, CA 92521, USA
- Neuroscience Graduate Program, University of California, Riverside, CA 92521, USA
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7
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Changes in aquaporins expression due to acute water restriction in naturally aging mice. J Physiol Biochem 2023; 79:71-81. [PMID: 36127549 DOI: 10.1007/s13105-022-00921-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 09/01/2022] [Indexed: 02/08/2023]
Abstract
Aquaporins (AQPs) are water channels in the cell membrane that regulate osmosis in response to rapid changes in intracellular and extracellular fluid concentration caused by extrinsic factors. While there are so many studies on the association of AQPs with muscular atrophy, sarcopenia, and Duchenne muscular dystrophy (DMD), the expression of AQP has not been verified in naturally aging mice or humans. Notably, due to the characteristics of AQPs, the difference in function cannot be evaluated without extrinsic factors such as acute water restriction. The purpose of this study was to investigate the changes in AQPs expression and function due to natural aging under acute water restriction conditions in aging mice. The expression of AQP4 was shown to decrease with aging similar to previous studies. However, for the first time, this study results confirmed that AQP1 expression increased in aging mice. In addition, the expression of Aqp1 decreased in the acute water restricted group compared to the control group after acute water restriction in aging mice. These results suggest that although the expression of AQP1 increases with aging, its function is reduced. We also confirmed that overexpression of Aqp1 can inhibit myotube differentiation and that knockdown can promote myotube differentiation through in vitro experiments. In conclusion, based on our results, we suggest that the AQP1 is an important factor in sarcopenia caused by natural aging accompanied by chronic dehydration.
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8
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Aslesh T, Al-aghbari A, Yokota T. Assessing the Role of Aquaporin 4 in Skeletal Muscle Function. Int J Mol Sci 2023; 24:ijms24021489. [PMID: 36675000 PMCID: PMC9865462 DOI: 10.3390/ijms24021489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/09/2023] [Accepted: 01/09/2023] [Indexed: 01/15/2023] Open
Abstract
Water transport across the biological membranes is mediated by aquaporins (AQPs). AQP4 and AQP1 are the predominantly expressed AQPs in the skeletal muscle. Since the discovery of AQP4, several studies have highlighted reduced AQP4 levels in Duchenne muscular dystrophy (DMD) patients and mouse models, and other neuromuscular disorders (NMDs) such as sarcoglycanopathies and dysferlinopathies. AQP4 loss is attributed to the destabilizing dystrophin-associated protein complex (DAPC) in DMD leading to compromised water permeability in the skeletal muscle fibers. However, AQP4 knockout (KO) mice appear phenotypically normal. AQP4 ablation does not impair physical activity in mice but limits them from achieving the performance demonstrated by wild-type mice. AQP1 levels were found to be upregulated in DMD models and are thought to compensate for AQP4 loss. Several groups investigated the expression of other AQPs in the skeletal muscle; however, these findings remain controversial. In this review, we summarize the role of AQP4 with respect to skeletal muscle function and findings in NMDs as well as the implications from a clinical perspective.
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Affiliation(s)
- Tejal Aslesh
- Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, 116 St. and 85 Ave., Edmonton, AB T6G 2E1, Canada
| | - Ammar Al-aghbari
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, 116 St. and 85 Ave., Edmonton, AB T6G 2E1, Canada
| | - Toshifumi Yokota
- Neuroscience and Mental Health Institute, Faculty of Medicine and Dentistry, University of Alberta, 116 St. and 85 Ave., Edmonton, AB T6G 2E1, Canada
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, 116 St. and 85 Ave., Edmonton, AB T6G 2E1, Canada
- The Friends of Garret Cumming Research and Muscular Dystrophy Canada HM Toupin Neurological Science Research Chair, 8812 112 St., Edmonton, AB T6G 2H7, Canada
- Correspondence: ; Tel.: +1-(780)-492-1102
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9
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Skauli N, Savchenko E, Ottersen OP, Roybon L, Amiry-Moghaddam M. Canonical Bone Morphogenetic Protein Signaling Regulates Expression of Aquaporin-4 and Its Anchoring Complex in Mouse Astrocytes. Front Cell Neurosci 2022; 16:878154. [PMID: 35518645 PMCID: PMC9067306 DOI: 10.3389/fncel.2022.878154] [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: 02/17/2022] [Accepted: 03/22/2022] [Indexed: 11/13/2022] Open
Abstract
Aquaporin-4 (AQP4) is the predominant water channel in the brain; it is enriched in astrocytic foot processes abutting vessels where it is anchored through an interaction with the dystrophin-associated protein (DAP) complex. Enhanced expression with concomitant mislocalization of AQP4 along astrocyte plasma membranes is a hallmark of several neurological conditions. Thus, there is an urgent need to identify which signaling pathways dictate AQP4 microdistribution. Here we show that canonical bone morphogenetic proteins (BMPs), particularly BMP2 and 4, upregulate AQP4 expression in astrocytes and dysregulate the associated DAP complex by differentially affecting its individual members. We further demonstrate the presence of BMP receptors and Smad1/5/9 pathway activation in BMP treated astrocytes. Our analysis of adult mouse brain reveals BMP2 and 4 in neurons and in a subclass of endothelial cells and activated Smad1/5/9 in astrocytes. We conclude that the canonical BMP-signaling pathway might be responsible for regulating the expression of AQP4 and of DAP complex proteins that govern the subcellular compartmentation of this aquaporin.
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Affiliation(s)
- Nadia Skauli
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Ekaterina Savchenko
- Stem Cell Laboratory for CNS Disease Modeling, Department of Experimental Medical Science, BMC D10, Lund University, Lund, Sweden
| | - Ole Petter Ottersen
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Karolinska Institutet, Stockholm, Sweden
| | - Laurent Roybon
- Stem Cell Laboratory for CNS Disease Modeling, Department of Experimental Medical Science, BMC D10, Lund University, Lund, Sweden
| | - Mahmood Amiry-Moghaddam
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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10
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Stefano MED, Ferretti V, Mozzetta C. Synaptic alterations as a neurodevelopmental trait of Duchenne muscular dystrophy. Neurobiol Dis 2022; 168:105718. [PMID: 35390481 DOI: 10.1016/j.nbd.2022.105718] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 03/28/2022] [Accepted: 03/29/2022] [Indexed: 01/14/2023] Open
Abstract
Dystrophinopaties, e.g., Duchenne muscular dystrophy (DMD), Becker muscular dystrophy and X-linked dilated cardiomyopathy are inherited neuromuscular diseases, characterized by progressive muscular degeneration, which however associate with a significant impact on general system physiology. The more severe is the pathology and its diversified manifestations, the heavier are its effects on organs, systems, and tissues other than muscles (skeletal, cardiac and smooth muscles). All dystrophinopaties are characterized by mutations in a single gene located on the X chromosome encoding dystrophin (Dp427) and its shorter isoforms, but DMD is the most devasting: muscular degenerations manifests within the first 4 years of life, progressively affecting motility and other muscular functions, and leads to a fatal outcome between the 20s and 40s. To date, after years of studies on both DMD patients and animal models of the disease, it has been clearly demonstrated that a significant percentage of DMD patients are also afflicted by cognitive, neurological, and autonomic disorders, of varying degree of severity. The anatomical correlates underlying neural functional damages are established during embryonic development and the early stages of postnatal life, when brain circuits, sensory and motor connections are still maturing. The impact of the absence of Dp427 on the development, differentiation, and consolidation of specific cerebral circuits (hippocampus, cerebellum, prefrontal cortex, amygdala) is significant, and amplified by the frequent lack of one or more of its lower molecular mass isoforms. The most relevant aspect, which characterizes DMD-associated neurological disorders, is based on morpho-functional alterations of selective synaptic connections within the affected brain areas. This pathological feature correlates neurological conditions of DMD to other severe neurological disorders, such as schizophrenia, epilepsy and autistic spectrum disorders, among others. This review discusses the organization and the role of the dystrophin-dystroglycan complex in muscles and neurons, focusing on the neurological aspect of DMD and on the most relevant morphological and functional synaptic alterations, in both central and autonomic nervous systems, described in the pathology and its animal models.
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Affiliation(s)
- Maria Egle De Stefano
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, 00185 Rome, Italy; Center for Research in Neurobiology Daniel Bovet, Sapienza University of Rome, 00185 Rome, Italy.
| | - Valentina Ferretti
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, 00185 Rome, Italy; Center for Research in Neurobiology Daniel Bovet, Sapienza University of Rome, 00185 Rome, Italy
| | - Chiara Mozzetta
- Institute of Molecular Biology and Pathology (IBPM), National Research Council (CNR) of Italy c/o Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, 00185 Rome, Italy
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Rikitake M, Hata J, Iida M, Seki F, Ito R, Komaki Y, Yamada C, Yoshimaru D, Okano HJ, Shirakawa T. Analysis of Brain Structure and Neural Organization in Dystrophin-Deficient Model Mice with Magnetic Resonance Imaging at 7 T. Open Neuroimag J 2022. [DOI: 10.2174/18744400-v15-e2202040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Background:
Dystrophin strengthens muscle cells; however, in muscular dystrophy, dystrophin is deficient due to an abnormal sugar chain. This abnormality occurs in skeletal muscle and in brain tissue.
Objective:
This study aimed to non-invasively analyze the neural organization of the brain in muscular dystrophy. We used a mouse model of muscular dystrophy to study whether changes in brain structure and neurodegeneration following dystrophin deficiency can be assessed by 7T magnetic resonance imaging.
Methods:
C57BL/10-mdx (X chromosome-linked muscular dystrophy) mice were used as the dystrophic mouse model and healthy mice were used as controls. Ventricular enlargement is one of the most common brain malformations in dystrophin-deficient patients. Therefore, we examined whether ventricular enlargement was observed in C57BL/10-mdx using transverse-relaxation weighted images. Brain parenchyma analysis was performed using diffusion MRI with diffusion tensor images and neurite orientation dispersion and density imaging. Parenchymal degeneration was assessed in terms of directional diffusion, nerve fiber diffusion, and dendritic scattering density.
Results:
For the volume of brain ventricles analyzed by T2WI, the average size was 1.5 times larger in mdx mice compared to control mice. In the brain parenchyma, a significant difference (p < 0.05) was observed in parameters indicating disturbances in the direction of nerve fibers and dendritic scattering density in the white matter region.
Conclusion:
Our results show that changes in brain structure due to dystrophin deficiency can be assessed in detail without tissue destruction by combining diffusion tensor images and neurite orientation dispersion and density imaging analyses.
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Lange J, Gillham O, Alkharji R, Eaton S, Ferrari G, Madej M, Flower M, Tedesco FS, Muntoni F, Ferretti P. Dystrophin deficiency affects human astrocyte properties and response to damage. Glia 2022; 70:466-490. [PMID: 34773297 DOI: 10.1002/glia.24116] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 10/21/2021] [Accepted: 10/22/2021] [Indexed: 01/03/2023]
Abstract
In addition to progressive muscular degeneration due to dystrophin mutations, 1/3 of Duchenne muscular dystrophy (DMD) patients present cognitive deficits. However, there is currently an incomplete understanding about the function of the multiple dystrophin isoforms in human brains. Here, we tested the hypothesis that dystrophin deficiency affects glial function in DMD and could therefore contribute to neural impairment. We investigated human dystrophin isoform expression with development and differentiation and response to damage in human astrocytes from control and induced pluripotent stem cells from DMD patients. In control cells, short dystrophin isoforms were up-regulated with development and their expression levels changed differently upon neuronal and astrocytic differentiation, as well as in 2-dimensional versus 3-dimensional astrocyte cultures. All DMD-astrocytes tested displayed altered morphology, proliferative activity and AQP4 expression. Furthermore, they did not show any morphological change in response to inflammatory stimuli and their number was significantly lower as compared to stimulated healthy astrocytes. Finally, DMD-astrocytes appeared to be more sensitive than controls to oxidative damage as shown by their increased cell death. Behavioral and metabolic defects in DMD-astrocytes were consistent with gene pathway dysregulation shared by lines with different mutations as demonstrated by bulk RNA-seq analysis. Together, our DMD model provides evidence for altered astrocyte function in DMD suggesting that defective astrocyte responses may contribute to neural impairment and might provide additional potential therapeutic targets.
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Affiliation(s)
- Jenny Lange
- Department of Developmental Biology and Cancer, Stem Cells and Regenerative Medicine Section, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Olivia Gillham
- Department of Developmental Biology and Cancer, Stem Cells and Regenerative Medicine Section, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Reem Alkharji
- Department of Developmental Biology and Cancer, Stem Cells and Regenerative Medicine Section, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Simon Eaton
- Department of Developmental Biology and Cancer, Stem Cells and Regenerative Medicine Section, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Giulia Ferrari
- Department of Cell and Developmental Biology, University College London, London, UK
| | - Monika Madej
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Michael Flower
- UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Francesco Saverio Tedesco
- Department of Cell and Developmental Biology, University College London, London, UK
- Dubowitz Neuromuscular Centre, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
- The Francis Crick Institute, 1 Midland Road, London, UK
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
- NIHR Great Ormond Street Hospital Biomedical Research Centre, Great Ormond Street Institute of Child Health, University College London, & Great Ormond Street Hospital Trust, London, UK
| | - Patrizia Ferretti
- Department of Developmental Biology and Cancer, Stem Cells and Regenerative Medicine Section, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
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Valente O, Messina R, Ingravallo G, Bellitti E, Zimatore DS, de Gennaro L, Abbrescia P, Pati R, Palazzo C, Nicchia GP, Trojano M, Signorelli F, Frigeri A. Alteration of the translational readthrough isoform AQP4ex induces redistribution and downregulation of AQP4 in human glioblastoma. Cell Mol Life Sci 2022; 79:140. [PMID: 35187599 PMCID: PMC8858924 DOI: 10.1007/s00018-021-04123-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 12/21/2021] [Accepted: 12/29/2021] [Indexed: 11/03/2022]
Abstract
AbstractGlioblastoma multiforme (GBM) is characterized by a remarkable cellular and molecular heterogeneity that make the behavior of this tumor highly variable and resistant to therapy. In addition, the most serious clinical complication of GBM and other brain tumors is the development of vasogenic edema which dramatically increase the intracranial pressure. In the present study we evaluate the expression, supramolecular organization and spatial distribution of AQP4 and AQP4ex, the new readthrough isoform of AQP4, in relationship with the degree of vasogenic brain edema and tumor progression. To this purpose, tissue samples from regions of tumor core, peritumoral and non-infiltrated tissues of each GBM patient (n = 31) were analyzed. Immunofluorescence experiments revealed that the expression of AQP4ex was almost absent in tumoral regions while the canonical AQP4 isoforms appear mostly delocalized. In peritumoral tissues, AQP4 expression was found altered in those perivascular astrocyte processes where AQP4ex appeared reduced and partially delocalized. Protein expression levels measured by immunoblot showed that global AQP4 was reduced mainly in the tumor core. Notably, the relative amount of AQP4ex was more severely reduced starting from the peritumoral region. BN-PAGE experiments showed that the supramolecular organization of AQP4 is only partially affected in GBM. Edema assessment by magnetic resonance imaging revealed that the level of AQP4ex downregulation correlated with edema severity. Finally, the degree of BBB alteration, measured with sodium fluorescein content in GBM biopsies, correlated with the edema index and AQP4ex downregulation. Altogether these data suggest that the AQP4ex isoform is critical in the triggering event of progressive downregulation and mislocalization of AQP4 in GBM, which may affect the integrity of the BBB and contributes to accumulation of edema in the peritumoral tissue. Thus, AQP4ex could be considered as a potential early biomarker of GBM progression.
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Zannetti A, Benga G, Brunetti A, Napolitano F, Avallone L, Pelagalli A. Role of Aquaporins in the Physiological Functions of Mesenchymal Stem Cells. Cells 2020; 9:cells9122678. [PMID: 33322145 PMCID: PMC7763964 DOI: 10.3390/cells9122678] [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: 11/06/2020] [Revised: 12/09/2020] [Accepted: 12/11/2020] [Indexed: 12/13/2022] Open
Abstract
Aquaporins (AQPs) are a family of membrane water channel proteins that control osmotically-driven water transport across cell membranes. Recent studies have focused on the assessment of fluid flux regulation in relation to the biological processes that maintain mesenchymal stem cell (MSC) physiology. In particular, AQPs seem to regulate MSC proliferation through rapid regulation of the cell volume. Furthermore, several reports have shown that AQPs play a crucial role in modulating MSC attachment to the extracellular matrix, their spread, and migration. Shedding light on how AQPs are able to regulate MSC physiological functions can increase our knowledge of their biological behaviours and improve their application in regenerative and reparative medicine.
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Affiliation(s)
- Antonella Zannetti
- Institute of Biostructure and Bioimaging, CNR, Via T. De Amicis 95, 80145 Naples, Italy
| | - Gheorghe Benga
- Romanian Academy, Cluj-Napoca Branch, Strada Republicii 9, 400015 Cluj-Napoca, Romania
| | - Arturo Brunetti
- Department of Advanced Biomedical Sciences, University of Naples Federico II, via Pansini 5, 80131 Naples, Italy
| | - Francesco Napolitano
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, via Veterinaria 1, 80137 Naples, Italy
- CEINGE-Biotecnologie Avanzate, Via Gaetano Salvatore 486, 80145 Naples, Italy
| | - Luigi Avallone
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, via Veterinaria 1, 80137 Naples, Italy
| | - Alessandra Pelagalli
- Institute of Biostructure and Bioimaging, CNR, Via T. De Amicis 95, 80145 Naples, Italy
- Department of Advanced Biomedical Sciences, University of Naples Federico II, via Pansini 5, 80131 Naples, Italy
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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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Belmaati Cherkaoui M, Vacca O, Izabelle C, Boulay AC, Boulogne C, Gillet C, Barnier JV, Rendon A, Cohen-Salmon M, Vaillend C. Dp71 contribution to the molecular scaffold anchoring aquaporine-4 channels in brain macroglial cells. Glia 2020; 69:954-970. [PMID: 33247858 DOI: 10.1002/glia.23941] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 11/13/2020] [Accepted: 11/17/2020] [Indexed: 02/06/2023]
Abstract
Intellectual disability in Duchenne muscular dystrophy has been associated with the loss of dystrophin-protein 71, Dp71, the main dystrophin-gene product in the adult brain. Dp71 shows major expression in perivascular macroglial endfeet, suggesting that dysfunctional glial mechanisms contribute to cognitive impairments. In the present study, we investigated the molecular alterations induced by a selective loss of Dp71 in mice, using semi-quantitative immunogold analyses in electron microscopy and immunofluorescence confocal analyses in brain sections and purified gliovascular units. In macroglial pericapillary endfeet of the cerebellum and hippocampus, we found a drastic reduction (70%) of the polarized distribution of aquaporin-4 (AQP4) channels, a 50% reduction of β-dystroglycan, and a complete loss of α1-syntrophin. Interestingly, in the hippocampus and cortex, these effects were not homogeneous: AQP4 and AQP4ex isoforms were mostly lost around capillaries but preserved in large vessels corresponding to pial arteries, penetrating cortical arterioles, and arterioles of the hippocampal fissure, indicating the presence of Dp71-independent pools of AQP4 in these vascular structures. In conclusion, the depletion of Dp71 strongly alters the distribution of AQP4 selectively in macroglial perivascular endfeet surrounding capillaries. This effect likely affects water homeostasis and blood-brain barrier functions and may thus contribute to the synaptic and cognitive defects associated with Dp71 deficiency.
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Affiliation(s)
| | - Ophélie Vacca
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris Saclay, Gif-sur-Yvette, France
| | - Charlotte Izabelle
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris Saclay, Gif-sur-Yvette, France
| | - Anne-Cécile Boulay
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, Unité Mixte de Recherche 7241CNRS, Unité 1050 INSERM, PSL Research University, Paris, France
| | - Claire Boulogne
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Cynthia Gillet
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Jean-Vianney Barnier
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris Saclay, Gif-sur-Yvette, France
| | - Alvaro Rendon
- UPMC Université Paris 06, INSERM, CNRS, Institut de la Vision, Sorbonne Universités, Paris, France
| | - Martine Cohen-Salmon
- Physiology and Physiopathology of the Gliovascular Unit Research Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, Unité Mixte de Recherche 7241CNRS, Unité 1050 INSERM, PSL Research University, Paris, France
| | - Cyrille Vaillend
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris Saclay, Gif-sur-Yvette, France
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17
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Verhoog QP, Holtman L, Aronica E, van Vliet EA. Astrocytes as Guardians of Neuronal Excitability: Mechanisms Underlying Epileptogenesis. Front Neurol 2020; 11:591690. [PMID: 33324329 PMCID: PMC7726323 DOI: 10.3389/fneur.2020.591690] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 10/26/2020] [Indexed: 12/11/2022] Open
Abstract
Astrocytes are key homeostatic regulators in the central nervous system and play important roles in physiology. After brain damage caused by e.g., status epilepticus, traumatic brain injury, or stroke, astrocytes may adopt a reactive phenotype. This process of reactive astrogliosis is important to restore brain homeostasis. However, persistent reactive astrogliosis can be detrimental for the brain and contributes to the development of epilepsy. In this review, we will focus on physiological functions of astrocytes in the normal brain as well as pathophysiological functions in the epileptogenic brain, with a focus on acquired epilepsy. We will discuss the role of astrocyte-related processes in epileptogenesis, including reactive astrogliosis, disturbances in energy supply and metabolism, gliotransmission, and extracellular ion concentrations, as well as blood-brain barrier dysfunction and dysregulation of blood flow. Since dysfunction of astrocytes can contribute to epilepsy, we will also discuss their role as potential targets for new therapeutic strategies.
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Affiliation(s)
- Quirijn P. Verhoog
- Leiden Academic Center for Drug Research, Leiden University, Leiden, Netherlands
- Department of Neuropathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Linda Holtman
- Leiden Academic Center for Drug Research, Leiden University, Leiden, Netherlands
| | - Eleonora Aronica
- Department of Neuropathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, Netherlands
| | - Erwin A. van Vliet
- Department of Neuropathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
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Gao M, Lu W, Shu Y, Yang Z, Sun S, Xu J, Gan S, Zhu S, Qiu G, Zhuo F, Xu S, Wang Y, Chen J, Wu X, Huang J. Poldip2 mediates blood-brain barrier disruption and cerebral edema by inducing AQP4 polarity loss in mouse bacterial meningitis model. CNS Neurosci Ther 2020; 26:1288-1302. [PMID: 32790044 PMCID: PMC7702237 DOI: 10.1111/cns.13446] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Revised: 06/27/2020] [Accepted: 07/05/2020] [Indexed: 12/20/2022] Open
Abstract
Background Specific highly polarized aquaporin‐4 (AQP4) expression is reported to play a crucial role in blood‐brain barrier (BBB) integrity and brain water transport balance. The upregulation of polymerase δ‐interacting protein 2 (Poldip2) was involved in aggravating BBB disruption following ischemic stroke. This study aimed to investigate whether Poldip2‐mediated BBB disruption and cerebral edema formation in mouse bacterial meningitis (BM) model occur via induction of AQP4 polarity loss. Methods and Results Mouse BM model was induced by injecting mice with group B hemolytic streptococci via posterior cistern. Recombinant human Poldip2 (rh‐Poldip2) was administered intranasally at 1 hour after BM induction. Small interfering ribonucleic acid (siRNA) targeting Poldip2 was administered by intracerebroventricular (i.c.v) injection at 48 hours before BM induction. A specific inhibitor of matrix metalloproteinases (MMPs), UK383367, was administered intravenously at 0.5 hour before BM induction. Western blotting, immunofluorescence staining, quantitative real‐time PCR, neurobehavioral test, brain water content test, Evans blue (EB) permeability assay, transmission electron microscopy (TEM), and gelatin zymography were carried out. The results showed that Poldip2 was upregulated and AQP4 polarity was lost in mouse BM model. Both Poldip2 siRNA and UK383367 improved neurobehavioral outcomes, alleviated brain edema, preserved the integrity of BBB, and relieved the loss of AQP4 polarity in BM model. Rh‐Poldip2 upregulated the expression of MMPs and glial fibrillary acidic protein (GFAP) and downregulated the expression of β‐dystroglycan (β‐DG), zonula occludens‐1 (ZO‐1), occludin, and claudin‐5; whereas Poldip2 siRNA downregulated the expression of MMPs and GFAP, and upregulated β‐DG, ZO‐1, occludin, and claudin‐5. Similarly, UK383367 downregulated the expression of GFAP and upregulated the expression of β‐DG, ZO‐1, occludin, and claudin‐5. Conclusion Poldip2 inhibition alleviated brain edema and preserved the integrity of BBB partially by relieving the loss of AQP4 polarity via MMPs/β‐DG pathway.
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Affiliation(s)
- Meng Gao
- Department of Anatomy, Chongqing Medical University, Chongqing, China
| | - Weitian Lu
- Department of Anatomy, Chongqing Medical University, Chongqing, China.,Institute of Neuroscience, Chongqing Medical University, Chongqing, China
| | - Yue Shu
- Department of Anatomy, Chongqing Medical University, Chongqing, China
| | - Zhengyu Yang
- Department of Anatomy, Chongqing Medical University, Chongqing, China
| | - Shanquan Sun
- Department of Anatomy, Chongqing Medical University, Chongqing, China.,Institute of Neuroscience, Chongqing Medical University, Chongqing, China
| | - Jin Xu
- Department of Anatomy, Chongqing Medical University, Chongqing, China.,Institute of Neuroscience, Chongqing Medical University, Chongqing, China
| | - Shengwei Gan
- Department of Anatomy, Chongqing Medical University, Chongqing, China.,Institute of Neuroscience, Chongqing Medical University, Chongqing, China
| | - Shujuan Zhu
- Department of Anatomy, Chongqing Medical University, Chongqing, China.,Institute of Neuroscience, Chongqing Medical University, Chongqing, China
| | - Guoping Qiu
- Department of Anatomy, Chongqing Medical University, Chongqing, China.,Institute of Neuroscience, Chongqing Medical University, Chongqing, China
| | - Fei Zhuo
- Department of Anatomy, Chongqing Medical University, Chongqing, China.,Institute of Neuroscience, Chongqing Medical University, Chongqing, China
| | - Shiye Xu
- Department of Anatomy, Chongqing Medical University, Chongqing, China.,Institute of Neuroscience, Chongqing Medical University, Chongqing, China
| | - Yiying Wang
- Department of Anatomy, Chongqing Medical University, Chongqing, China
| | - Junhong Chen
- Department of Anatomy, Chongqing Medical University, Chongqing, China
| | - Xuan Wu
- Department of Neurosurgery, The Second Affiliated Hospital, Chongqing Medical University, Chongqing, China
| | - Juan Huang
- Department of Anatomy, Chongqing Medical University, Chongqing, China.,Institute of Neuroscience, Chongqing Medical University, Chongqing, China
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Naidoo M, Anthony K. Dystrophin Dp71 and the Neuropathophysiology of Duchenne Muscular Dystrophy. Mol Neurobiol 2020; 57:1748-1767. [PMID: 31836945 PMCID: PMC7060961 DOI: 10.1007/s12035-019-01845-w] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 11/22/2019] [Indexed: 12/13/2022]
Abstract
Duchenne muscular dystrophy (DMD) is caused by frameshift mutations in the DMD gene that prevent the body-wide translation of its protein product, dystrophin. Besides a severe muscle phenotype, cognitive impairment and neuropsychiatric symptoms are prevalent. Dystrophin protein 71 (Dp71) is the major DMD gene product expressed in the brain and mutations affecting its expression are associated with the DMD neuropsychiatric syndrome. As with dystrophin in muscle, Dp71 localises to dystrophin-associated protein complexes in the brain. However, unlike in skeletal muscle; in the brain, Dp71 is alternatively spliced to produce many isoforms with differential subcellular localisations and diverse cellular functions. These include neuronal differentiation, adhesion, cell division and excitatory synapse organisation as well as nuclear functions such as nuclear scaffolding and DNA repair. In this review, we first describe brain involvement in DMD and the abnormalities observed in the DMD brain. We then review the gene expression, RNA processing and functions of Dp71. We review genotype-phenotype correlations and discuss emerging cellular/tissue evidence for the involvement of Dp71 in the neuropathophysiology of DMD. The literature suggests changes observed in the DMD brain are neurodevelopmental in origin and that their risk and severity is associated with a cumulative loss of distal DMD gene products such as Dp71. The high risk of neuropsychiatric syndromes in Duchenne patients warrants early intervention to achieve the best possible quality of life. Unravelling the function and pathophysiological significance of dystrophin in the brain has become a high research priority to inform the development of brain-targeting treatments for Duchenne.
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Affiliation(s)
- Michael Naidoo
- Centre for Physical Activity and Life Sciences, Faculty of Arts, Science and Technology, University of Northampton, University Drive, Northampton, Northamptonshire, NN1 5PH, UK
| | - Karen Anthony
- Centre for Physical Activity and Life Sciences, Faculty of Arts, Science and Technology, University of Northampton, University Drive, Northampton, Northamptonshire, NN1 5PH, UK.
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Hoddevik EH, Rao SB, Zahl S, Boldt HB, Ottersen OP, Amiry-Moghaddam M. Organisation of extracellular matrix proteins laminin and agrin in pericapillary basal laminae in mouse brain. Brain Struct Funct 2020; 225:805-816. [PMID: 32072250 PMCID: PMC7046580 DOI: 10.1007/s00429-020-02036-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Accepted: 01/29/2020] [Indexed: 01/08/2023]
Abstract
Evidence suggests that extracellular matrix molecules of perivascular basal laminae help orchestrate the molecular assemblies at the gliovascular interface. Specifically, laminin and agrin are thought to tether the dystrophin-associated protein (DAP) complex to the astrocytic basal lamina. This complex includes α-syntrophin (α-Syn), which is believed to anchor aquaporin-4 (AQP4) to astrocytic endfoot membrane domains. We have previously shown that the size of the perivascular AQP4 pool differs considerably between brain regions in an α-Syn-dependent manner. Also, both AQP4 and α-Syn occur at higher densities in endfoot membrane domains facing pericytes than in endfoot membrane domains facing endothelial cells. The heterogeneous distribution of AQP4 at the regional and capillary level has been attributed to a direct interaction between AQP4 and α-Syn. This would be challenged (1) if the microdistributions of laminin and agrin fail to align with those of DAP and AQP4 and (2) if targeted deletion of α-Syn leads to a loss of laminin and/or agrin. Here, we provide the first detailed and quantitative analysis of laminin and agrin in brain basal laminae of mice. We show that the microdistributions of these molecules vary in a fashion that is well aligned with the previously reported microdistribution of AQP4. We also demonstrate that the expression patterns of laminin and agrin are insensitive to targeted deletion of α-Syn, suggesting that α-Syn deletion affects AQP4 directly and not indirectly via laminin or agrin. These data fill remaining voids in the current model of how key molecules are assembled and tethered at the gliovascular interface.
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Affiliation(s)
- Eystein Hellstrøm Hoddevik
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Blindern, Post box 1105, 0317, Oslo, Norway
- Department of Pathology, Oslo University Hospital, Oslo, Norway
| | - Shreyas Balachandra Rao
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Blindern, Post box 1105, 0317, Oslo, Norway
| | - Soulmaz Zahl
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Blindern, Post box 1105, 0317, Oslo, Norway
| | - Henning Bünsow Boldt
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Blindern, Post box 1105, 0317, Oslo, Norway
- Department of Pathology, Odense University Hospital, Odense, Denmark
| | - Ole Petter Ottersen
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Blindern, Post box 1105, 0317, Oslo, Norway
- President's Office, Karolinska Institutet, Nobels väg 6, 171 77, Stockholm, Sweden
| | - Mahmood Amiry-Moghaddam
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Blindern, Post box 1105, 0317, Oslo, Norway.
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21
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Uncoupling of the Astrocyte Syncytium Differentially Affects AQP4 Isoforms. Cells 2020; 9:cells9020382. [PMID: 32046059 PMCID: PMC7072498 DOI: 10.3390/cells9020382] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 01/29/2020] [Accepted: 02/04/2020] [Indexed: 11/25/2022] Open
Abstract
The water channel protein aquaporin-4 (AQP4) and the gap junction forming proteins connexin-43 (Cx43) and connexin-30 (Cx30) are astrocytic proteins critically involved in brain water and ion homeostasis. While AQP4 is mainly involved in water flux across the astrocytic endfeet membranes, astrocytic gap junctions provide syncytial coupling allowing intercellular exchange of water, ions, and other molecules. We have previously shown that mice with targeted deletion of Aqp4 display enhanced gap junctional coupling between astrocytes. Here, we investigate whether uncoupling of the astrocytic syncytium by deletion of the astrocytic connexins Cx43 and Cx30 affects AQP4 membrane localization and expression. By using quantitative immunogold cytochemistry, we show that deletion of astrocytic connexins leads to a substantial reduction of perivascular AQP4, concomitant with a down-regulation of total AQP4 protein and mRNA. Isoform expression analysis shows that while the level of the predominant AQP4 M23 isoform is reduced in Cx43/Cx30 double deficient hippocampal astrocytes, the levels of M1, and the alternative translation AQP4ex isoform protein levels are increased. These findings reveal a complex interdependence between AQP4 and connexins, which are both significantly involved in homeostatic functions and astrogliopathologies.
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22
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Podkalicka P, Mucha O, Dulak J, Loboda A. Targeting angiogenesis in Duchenne muscular dystrophy. Cell Mol Life Sci 2019; 76:1507-1528. [PMID: 30770952 PMCID: PMC6439152 DOI: 10.1007/s00018-019-03006-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Revised: 12/28/2018] [Accepted: 01/07/2019] [Indexed: 02/07/2023]
Abstract
Duchenne muscular dystrophy (DMD) represents one of the most devastating types of muscular dystrophies which affect boys already at early childhood. Despite the fact that the primary cause of the disease, namely the lack of functional dystrophin is known already for more than 30 years, DMD still remains an incurable disease. Thus, an enormous effort has been made during recent years to reveal novel mechanisms that could provide therapeutic targets for DMD, especially because glucocorticoids treatment acts mostly symptomatic and exerts many side effects, whereas the effectiveness of genetic approaches aiming at the restoration of functional dystrophin is under the constant debate. Taking into account that dystrophin expression is not restricted to muscle cells, but is present also in, e.g., endothelial cells, alterations in angiogenesis process have been proposed to have a significant impact on DMD progression. Indeed, already before the discovery of dystrophin, several abnormalities in blood vessels structure and function have been revealed, suggesting that targeting angiogenesis could be beneficial in DMD. In this review, we will summarize current knowledge about the angiogenesis status both in animal models of DMD as well as in DMD patients, focusing on different organs as well as age- and sex-dependent effects. Moreover, we will critically discuss some approaches such as modulation of vascular endothelial growth factor or nitric oxide related pathways, to enhance angiogenesis and attenuate the dystrophic phenotype. Additionally, we will suggest the potential role of other mediators, such as heme oxygenase-1 or statins in those processes.
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Affiliation(s)
- Paulina Podkalicka
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland
| | - Olga Mucha
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland
| | - Jozef Dulak
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland
| | - Agnieszka Loboda
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland.
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23
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Chronic stress impairs the aquaporin-4-mediated glymphatic transport through glucocorticoid signaling. Psychopharmacology (Berl) 2019; 236:1367-1384. [PMID: 30607477 DOI: 10.1007/s00213-018-5147-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 12/03/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND The glymphatic system has recently been proposed to function as a brain-wide macroscopic system for the clearance of potentially harmful molecules, such as amyloid beta (e.g., Aβ), from the brain parenchyma. Previous literatures have established that the glymphatic function is dramatically suppressed by aging, traumatic brain injury, and some diseases. However, the effect of chronic stress on the glymphatic function and its underlying mechanism remains largely unknown. METHODS Adult mice were randomly divided into four groups: chronic unpredictable mild stress (CUMS)-treated group, CUMS simultaneously treated with mifepristone (MFP) group, dexamethasone (DEX)-treated group, and control group. Stress response was observed by assessing the change of body weight, plasma corticosterone level, and behavior tests. The level of Aβ42 in cerebral tissue was assessed by ELISA. The glymphatic function was determined by using fluorescence tracer injection. The expression and localization of aquaporin-4 (AQP4) were evaluated by immunohistochemistry and western blot. The transcription level of AQP4 and anchoring molecules was evaluated by real-time PCR. FINDINGS Compared with control group, CUMS-treated mice exhibited the impairment of global glymphatic function especially in the anterior brain. This change was accompanied by the decreased expression and polarization of AQP4, reduced transcription of AQP4, agrin, laminin, and dystroglycan in the anterior cortex. Similarly, the glucocorticoid receptor (GR) agonist DEX exposure could reduce the glymphatic function and AQP4 expression. Moreover, the GR antagonist MFP treatment could significantly rescue the glymphatic function and reverse the expression and polarization of AQP4 impaired by CUMS. CONCLUSION Chronic stress could impair the AQP4-mediated glymphatic transport in the brain through glucocorticoid signaling. Our results also suggest that GR antagonist could be beneficial to rescue the glymphatic function suppressed by chronic stress.
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24
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Palazzo C, Buccoliero C, Mola MG, Abbrescia P, Nicchia GP, Trojano M, Frigeri A. AQP4ex is crucial for the anchoring of AQP4 at the astrocyte end-feet and for neuromyelitis optica antibody binding. Acta Neuropathol Commun 2019; 7:51. [PMID: 30935410 PMCID: PMC6444679 DOI: 10.1186/s40478-019-0707-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 03/21/2019] [Indexed: 12/18/2022] Open
Abstract
Brain water homeostasis is essential for the appropriate control of neuronal activity. Furthermore, the encasement of the central nervous system (CNS) by a hard structure, greatly limits its tolerance for the volume changes occurring with acute brain edema, which quickly leads to severe damage or death. The recent discovery of the extended isoform of AQP4 (AQP4ex), generated by translational readthrough, revealed a potential new mechanism of water transport regulation and polarization at the blood-brain-barrier level. In the present study we used CRISPR/Cas9 technology to generate an AQP4ex−/− mouse model and evaluate the effect on the overall AQP4 expression, polarization, supramolecular organization in orthogonal arrays of particles (OAPs) and neuromyelitis optica (NMO-IgG) autoantibodies binding. AQP4ex removal did not cause a decrease in total AQP4 protein expression but completely suppressed the specific location of AQP4 at the astrocyte endfeet. Without AQP4ex, AQP4 was mislocalized and α-syntrophin expression, the selective partner for AQP4 localization, was partially altered. The supramolecular organization of AQP4 in OAPs was subtly altered. Indeed, the absence of AQP4ex reduced the size of AQP4-OAPs but the number of AQP4-OAP pools remained largely the same. More importantly, AQP4ex resulted critical for the binding of pathogenic human NMO-IgG autoantibodies to the brain. Indeed, the absence of AQP4ex completely abolished the binding of NMO-IgG at the perivascular astrocyte endfeet. This study provides the first direct evidence in vivo on the specific role of AQP4ex in AQP4 perivascular OAPs assembly and confinement and reveals AQP4ex as new and important player in neuromyelitis optica.
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25
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Min R, van der Knaap MS. Genetic defects disrupting glial ion and water homeostasis in the brain. Brain Pathol 2019; 28:372-387. [PMID: 29740942 PMCID: PMC8028498 DOI: 10.1111/bpa.12602] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 03/02/2018] [Indexed: 12/23/2022] Open
Abstract
Electrical activity of neurons in the brain, caused by the movement of ions between intracellular and extracellular compartments, is the basis of all our thoughts and actions. Maintaining the correct ionic concentration gradients is therefore crucial for brain functioning. Ion fluxes are accompanied by the displacement of osmotically obliged water. Since even minor brain swelling leads to severe brain damage and even death, brain ion and water movement has to be tightly regulated. Glial cells, in particular astrocytes, play a key role in ion and water homeostasis. They are endowed with specific channels, pumps and carriers to regulate ion and water flow. Glial cells form a large panglial syncytium to aid the uptake and dispersal of ions and water, and make extensive contacts with brain fluid barriers for disposal of excess ions and water. Genetic defects in glial proteins involved in ion and water homeostasis disrupt brain functioning, thereby leading to neurological diseases. Since white matter edema is often a hallmark disease feature, many of these diseases are characterized as leukodystrophies. In this review we summarize our current understanding of inherited glial diseases characterized by disturbed brain ion and water homeostasis by integrating findings from MRI, genetics, neuropathology and animal models for disease. We discuss how mutations in different glial proteins lead to disease, and highlight the similarities and differences between these diseases. To come to effective therapies for this group of diseases, a better mechanistic understanding of how glial cells shape ion and water movement in the brain is crucial.
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Affiliation(s)
- Rogier Min
- Department of Child Neurology, Amsterdam Neuroscience, VU University Medical Center, Amsterdam, The Netherlands.,Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands
| | - Marjo S van der Knaap
- Department of Child Neurology, Amsterdam Neuroscience, VU University Medical Center, Amsterdam, The Netherlands.,Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands
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26
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The expression of aquaporin-4 is regulated based on innervation in skeletal muscles. J Muscle Res Cell Motil 2018; 39:17-23. [PMID: 29869011 DOI: 10.1007/s10974-018-9494-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 06/01/2018] [Indexed: 10/14/2022]
Abstract
Aquaporin-4 (AQP4) is a selective water channel, which expresses on the plasma membrane of myofibers and regulates the osmotic pressure, energy metabolism and morphological changes in myofibers by modulating water transport across sarcolemma in skeletal muscles. Although the physiological roles of AQP4 have been gradually clarified in skeletal muscles, the regulatory mechanisms of AQP4 expression have been poorly understood in skeletal muscles. Recently, it was reported that the expression of AQP4 decreased in atrophied skeletal muscles following sciatic nerve transection, but not tail-suspension. Therefore, expecting that the nerve supply to myofibers would be one of the major regulatory factors regulating AQP4 expression in skeletal muscles, we investigated whether the expression patterns of AQP4 were changed in skeletal muscles by denervation and subsequent reinnervation. As a result, while the APQ4 expression levels were significantly decreased by sciatic nerve freezing-induced denervation, subsequently the expression levels of AQP4 were fully restored during reinnervation in skeletal muscles (p < 0.05, respectively). On the other hand, the expression levels of α1-syntrophin and AQP1, which are respectively structural and functional related AQP4 factors, were stably maintained during the denervation and subsequent reinnervation. Therefore, the present study demonstrated that the expression of AQP4 may be regulated depending on the innervation to skeletal muscles. Moreover, AQP4 regulatory mechanisms may be fundamentally different to those of AQP1 in skeletal muscles.
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27
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Simon MJ, Murchison C, Iliff JJ. A transcriptome-based assessment of the astrocytic dystrophin-associated complex in the developing human brain. J Neurosci Res 2018; 96:180-193. [PMID: 28509351 PMCID: PMC5995340 DOI: 10.1002/jnr.24082] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 03/23/2017] [Accepted: 04/20/2017] [Indexed: 11/10/2022]
Abstract
Astrocytes play a critical role in regulating the interface between the cerebral vasculature and the central nervous system. Contributing to this is the astrocytic endfoot domain, a specialized structure that ensheathes the entirety of the vasculature and mediates signaling between endothelial cells, pericytes, and neurons. The astrocytic endfoot has been implicated as a critical element of the glymphatic pathway, and changes in protein expression profiles in this cellular domain are linked to Alzheimer's disease pathology. Despite this, basic physiological properties of this structure remain poorly understood including the developmental timing of its formation, and the protein components that localize there to mediate its functions. Here we use human transcriptome data from male and female subjects across several developmental stages and brain regions to characterize the gene expression profile of the dystrophin-associated complex (DAC), a known structural component of the astrocytic endfoot that supports perivascular localization of the astroglial water channel aquaporin-4. Transcriptomic profiling is also used to define genes exhibiting parallel expression profiles to DAC elements, generating a pool of candidate genes that encode gene products that may contribute to the physiological function of the perivascular astrocytic endfoot domain. We found that several genes encoding transporter proteins are transcriptionally associated with DAC genes.
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Affiliation(s)
- Matthew J. Simon
- Neuroscience Graduate Program, Oregon Health & Science University, Portland, OR, USA
- Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR, USA
| | - Charles Murchison
- Department of Neurology, Oregon Health & Science University, Portland, OR, USA
| | - Jeffrey J. Iliff
- Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR, USA
- Knight Cardiovascular Institute. Oregon Health & Science University, Portland, OR, USA
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28
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Dynamics of surface neurotransmitter receptors and transporters in glial cells: Single molecule insights. Cell Calcium 2017; 67:46-52. [PMID: 29029790 DOI: 10.1016/j.ceca.2017.08.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 08/21/2017] [Accepted: 08/21/2017] [Indexed: 11/22/2022]
Abstract
The surface dynamics of neurotransmitter receptors and transporters, as well as ion channels, has been well-documented in neurons, revealing complex molecular behaviour and key physiological functions. However, our understanding of the membrane trafficking and dynamics of the signalling molecules located at the plasma membrane of glial cells is still in its infancy. Yet, recent breakthroughs in the field of glial cells have been obtained using combination of superresolution microscopy, single molecule imaging, and electrophysiological recordings. Here, we review our current knowledge on the surface dynamics of neurotransmitter receptors, transporters and ion channels, in glial cells. It has emerged that the brain cell network activity, synaptic activity, and calcium signalling, regulate the surface distribution and dynamics of these molecules. Remarkably, the dynamics of a given neurotransmitter receptor/transporter at the plasma membrane of a glial cell or neuron is unique, revealing the existence of cell-type specific regulatory pathways. Thus, investigating the dynamics of signalling proteins at the surface of glial cells will likely shed new light on our understanding of glial cell physiology and pathology.
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29
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Ishido M, Nakamura T. Marked decrease of aquaporin-4 protein is independent of the changes in α1-syntrophin and TRPV4 levels in response to denervation-induced muscle atrophy in vivo. J Muscle Res Cell Motil 2017; 38:175-181. [PMID: 28488242 DOI: 10.1007/s10974-017-9471-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 05/03/2017] [Indexed: 11/28/2022]
Abstract
Aquaporin-4 (AQP4) is a selective water channel mediating water transport across cell membranes in skeletal muscles. Recently, it was noted that AQP4 is one of the key molecules regulating muscle morphology. Indeed, the AQP4 accumulation level was stably maintained in hypertrophied skeletal muscles. On the other hand, whether the AQP4 accumulation level is stably maintained in atrophied muscles remains poorly understood. The present study investigated the changes in the AQP4 accumulation level in the atrophied muscles at 2 weeks after denervation. As a result, the accumulation level of AQP4 in the atrophied muscle was significantly decreased compared with that in the control muscle (p < 0.05). Interestingly, the accumulation level of α1-syntrophin, which is an essential factor in regulating the stable accumulation level of AQP4, was stably maintained in the atrophied muscles. On the other hand, the accumulation level of the transient receptor potential vanilloid 4 (TRPV4), which contributes to cell volume control via interaction with AQP4, was significantly increased in the atrophied muscles compared with that in the control muscle (p < 0.05). Therefore, the present study suggested that the imbalance between the AQP4 accumulation level and skeletal muscle volume may be induced in the atrophied muscles by denervation, and the decrease in the accumulation level of AQP4 may be accompanied by defects in the functional and structural relationships with α1-syntrophin and TRPV4.
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Affiliation(s)
- Minenori Ishido
- Section for Health-related Physical Education, Division of Human Sciences, Faculty of Engineering, Osaka Institute of Technology, Ohmiya, Asahi-ku, Osaka, 535-8585, Japan.
| | - Tomohiro Nakamura
- Section for Health-related Physical Education, Division of Human Sciences, Faculty of Engineering, Osaka Institute of Technology, Ohmiya, Asahi-ku, Osaka, 535-8585, Japan
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30
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Eidsvaag VA, Enger R, Hansson HA, Eide PK, Nagelhus EA. Human and mouse cortical astrocytes differ in aquaporin-4 polarization toward microvessels. Glia 2017; 65:964-973. [PMID: 28317216 PMCID: PMC5413834 DOI: 10.1002/glia.23138] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 02/19/2017] [Accepted: 02/20/2017] [Indexed: 12/02/2022]
Abstract
Aquaporin‐4 (AQP4), the predominant water channel in the brain, is expressed in astrocytes and ependymal cells. In rodents AQP4 is highly polarized to perivascular astrocytic endfeet and loss of AQP4 polarization is associated with disease. The present study was undertaken to compare the expression pattern of AQP4 in human and mouse cortical astrocytes. Cortical tissue specimens were sampled from 11 individuals undergoing neurosurgery wherein brain tissue was removed as part of the procedure, and compared with cortical tissue from 5 adult wild‐type mice processed similarly. The tissue samples were immersion‐fixed and prepared for AQP4 immunogold electron microscopy, allowing quantitative assessment of AQP4's subcellular distribution. In mouse we found that AQP4 water channels were prominently clustered around vessels, being 5 to 10‐fold more abundant in astrocytic endfoot membranes facing the capillary endothelium than in parenchymal astrocytic membranes. In contrast, AQP4 was markedly less polarized in human astrocytes, being only two to three‐fold enriched in astrocytic endfoot membranes adjacent to capillaries. The lower degree of AQP4 polarization in human subjects (1/3 of that in mice) was mainly due to higher AQP4 expression in parenchymal astrocytic membranes. We conclude that there are hitherto unrecognized species differences in AQP4 polarization toward microvessels in the cerebral cortex.
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Affiliation(s)
- Vigdis Andersen Eidsvaag
- Department of Neurosurgery, Oslo University Hospital, Rikshospitalet, Oslo, 0027, Norway.,Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.,GliaLab and Letten Centre, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, 0317, Norway
| | - Rune Enger
- GliaLab and Letten Centre, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, 0317, Norway.,Department of Neurology, Oslo University Hospital, Rikshospitalet, Oslo, 0027, Norway
| | - Hans-Arne Hansson
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Göteborg, Sweden
| | - Per Kristian Eide
- Department of Neurosurgery, Oslo University Hospital, Rikshospitalet, Oslo, 0027, Norway.,Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Erlend A Nagelhus
- GliaLab and Letten Centre, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, 0317, Norway.,Department of Neurology, Oslo University Hospital, Rikshospitalet, Oslo, 0027, Norway
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31
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Factors determining the density of AQP4 water channel molecules at the brain-blood interface. Brain Struct Funct 2016; 222:1753-1766. [PMID: 27629271 PMCID: PMC5406442 DOI: 10.1007/s00429-016-1305-y] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 09/04/2016] [Indexed: 10/27/2022]
Abstract
Perivascular endfeet of astrocytes are enriched with aquaporin-4 (AQP4)-a water channel that is critically involved in water transport at the brain-blood interface and that recently was identified as a key molecule in a system for waste clearance. The factors that determine the size of the perivascular AQP4 pool remain to be identified. Here we show that the size of this pool differs considerably between brain regions, roughly mirroring regional differences in Aqp4 mRNA copy numbers. We demonstrate that a targeted deletion of α-syntrophin-a member of the dystrophin complex responsible for AQP4 anchoring-removes a substantial and fairly constant proportion (79-94 %) of the perivascular AQP4 pool across the central nervous system (CNS). Quantitative immunogold analyses of AQP4 and α-syntrophin in perivascular membranes indicate that there is a fixed stoichiometry between these two molecules. Both molecules occur at higher densities in endfoot membrane domains facing pericytes than in endfoot membrane domains facing endothelial cells. Our data suggest that irrespective of region, endfoot targeting of α-syntrophin is the single most important factor determining the size of the perivascular AQP4 pool and hence the capacity for water transport at the brain-blood interface.
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32
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Ishido M, Nakamura T. Aquaporin-4 Protein Is Stably Maintained in the Hypertrophied Muscles by Functional Overload. Acta Histochem Cytochem 2016; 49:89-95. [PMID: 27462134 PMCID: PMC4939316 DOI: 10.1267/ahc.16005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 05/19/2016] [Indexed: 11/22/2022] Open
Abstract
Aquaporin-4 (AQP4) is a selective water channel that is located on the plasma membrane of myofibers in skeletal muscle and is bound to α1-syntrophin. It is considered that AQP4 is involved in the modulation of homeostasis in myofibers through the regulation of water transport and osmotic pressure. However, it remains unclear whether AQP4 expression is altered by skeletal muscle hypertrophy to modulate water homeostasis in myofibers. The present study investigated the effect of muscle hypertrophy on the changes in AQP4 and α1-syntrophin expression patterns in myofibers. Novel findings indicated in the present study were as follows: 1) Expression levels of AQP4 and α1-syntrophin were stably maintained in hypertrophied muscles, and 2) AQP4 was not expressed in the myofibers containing the slow-type myosin heavy chain isoform (MHC) with or without the presence of fast-type MHC. The present study suggests that AQP4 may regulate the efficiency of water transport in hypertrophied myofibers through its interaction with α1-syntrophin. In addition, this study suggests that AQP4 expression may be inhibited by a regulatory mechanism activated under physiological conditions that induces the expression of slow-type MHC in skeletal muscles.
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Affiliation(s)
- Minenori Ishido
- Section for Health-related Physical Education, Division of Human Sciences, Faculty of Engineering, Osaka Institute of Technology
| | - Tomohiro Nakamura
- Section for Health-related Physical Education, Division of Human Sciences, Faculty of Engineering, Osaka Institute of Technology
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33
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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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Stokum JA, Mehta RI, Ivanova S, Yu E, Gerzanich V, Simard JM. Heterogeneity of aquaporin-4 localization and expression after focal cerebral ischemia underlies differences in white versus grey matter swelling. Acta Neuropathol Commun 2015; 3:61. [PMID: 26419740 PMCID: PMC4588314 DOI: 10.1186/s40478-015-0239-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 09/17/2015] [Indexed: 12/21/2022] Open
Abstract
INTRODUCTION Ischemic stroke, a major cause of mortality, is frequently accompanied by life-threatening cerebral edema. Aquaporin-4 (Aqp4), an astrocytic transmembrane water channel, is an important molecular contributor to cerebral edema formation. Past studies of Aqp4 expression and localization after ischemia examined grey matter exclusively. However, as white matter astrocytes differ developmentally, physiologically, and molecularly from grey matter astrocytes, we hypothesized that functionally important regional heterogeneity exists in Aqp4 expression and subcellular localization following cerebral ischemia. RESULTS Subcellular localization of Aqp4 was compared between cortical and white matter astrocytes in postmortem specimens of patients with focal ischemic stroke versus controls. Subcellular localization and expression of Aqp4 was examined in rats subjected to experimental stroke. Volumetric analysis was performed on the cortex and white matter of rats subjected to experimental stroke. Following cerebral ischemia, cortical astrocytes exhibited reduced perivascular Aqp4 and unchanged Aqp4 protein abundance. In contrast, white matter astrocytes exhibited increased perivascular and plasmalemmal Aqp4 and a 2.2- to 6.2-fold increase in Aqp4 isoform abundance. Ischemic white matter swelled by approximately 40 %, while cortex swelled by approximately 9 %. CONCLUSIONS The findings reported here raise the possibility that cerebral white matter may play a heretofore underappreciated role in the formation of cerebral edema following ischemia.
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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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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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Hendriksen RG, Hoogland G, Schipper S, Hendriksen JG, Vles JS, Aalbers MW. A possible role of dystrophin in neuronal excitability: A review of the current literature. Neurosci Biobehav Rev 2015; 51:255-62. [DOI: 10.1016/j.neubiorev.2015.01.023] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 01/18/2015] [Accepted: 01/31/2015] [Indexed: 10/24/2022]
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Szokol K, Heuser K, Tang W, Jensen V, Enger R, Bedner P, Steinhäuser C, Taubøll E, Ottersen OP, Nagelhus EA. Augmentation of Ca(2+) signaling in astrocytic endfeet in the latent phase of temporal lobe epilepsy. Front Cell Neurosci 2015; 9:49. [PMID: 25762896 PMCID: PMC4340203 DOI: 10.3389/fncel.2015.00049] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/01/2015] [Indexed: 11/13/2022] Open
Abstract
Astrocytic endfeet are specialized cell compartments whose important homeostatic roles depend on their enrichment of water and ion channels anchored by the dystrophin associated protein complex (DAPC). This protein complex is known to disassemble in patients with mesial temporal lobe epilepsy and in the latent phase of experimental epilepsies. The mechanistic underpinning of this disassembly is an obvious target of future therapies, but remains unresolved. Here we show in a kainate model of temporal lobe epilepsy that astrocytic endfeet display an enhanced stimulation-evoked Ca(2+) signal that outlast the Ca(2+) signal in the cell bodies. While the amplitude of this Ca(2+) signal is reduced following group I/II metabotropic receptor (mGluR) blockade, the duration is sustained. Based on previous studies it has been hypothesized that the molecular disassembly in astrocytic endfeet is caused by dystrophin cleavage mediated by Ca(2+) dependent proteases. Using a newly developed genetically encoded Ca(2+) sensor, the present study bolsters this hypothesis by demonstrating long-lasting, enhanced stimulation-evoked Ca(2+) signals in astrocytic endfeet.
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Affiliation(s)
- Karolina Szokol
- Department of Neurology, Oslo University Hospital Oslo, Norway ; Centre for Molecular Medicine Norway, The Nordic EMBL Partnership, University of Oslo Oslo, Norway ; Letten Centre and GliaLab, Department of Physiology, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
| | - Kjell Heuser
- Department of Neurology, Oslo University Hospital Oslo, Norway ; Letten Centre and GliaLab, Department of Physiology, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
| | - Wannan Tang
- Centre for Molecular Medicine Norway, The Nordic EMBL Partnership, University of Oslo Oslo, Norway ; Letten Centre and GliaLab, Department of Physiology, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
| | - Vidar Jensen
- Centre for Molecular Medicine Norway, The Nordic EMBL Partnership, University of Oslo Oslo, Norway ; Letten Centre and GliaLab, Department of Physiology, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
| | - Rune Enger
- Department of Neurology, Oslo University Hospital Oslo, Norway ; Centre for Molecular Medicine Norway, The Nordic EMBL Partnership, University of Oslo Oslo, Norway ; Letten Centre and GliaLab, Department of Physiology, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
| | - Peter Bedner
- Institute of Cellular Neurosciences, University of Bonn Bonn, Germany
| | | | - Erik Taubøll
- Department of Neurology, Oslo University Hospital Oslo, Norway
| | | | - Erlend A Nagelhus
- Department of Neurology, Oslo University Hospital Oslo, Norway ; Centre for Molecular Medicine Norway, The Nordic EMBL Partnership, University of Oslo Oslo, Norway ; Letten Centre and GliaLab, Department of Physiology, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
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Wang WW, Xie CL, Zhou LL, Wang GS. The function of aquaporin4 in ischemic brain edema. Clin Neurol Neurosurg 2014; 127:5-9. [PMID: 25306413 DOI: 10.1016/j.clineuro.2014.09.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 06/17/2014] [Accepted: 09/19/2014] [Indexed: 02/01/2023]
Abstract
Cerebral ischemia injury is a primary cause of human death and long-term disability. We know that the cerebral edema induced by ischemia injury has a fatal effect on humans, which is the main cause of death for cerebral ischemia because it produces elevated intracranial pressure that leads to secondary brain damage, such as further impaired vascular perfusion and herniation of brain. Therefore, reducing the severity of brain edema has become the main therapeutic strategy for the treatment of CI. However, current treatment options for brain edema are limited and problematic. Therefore, finding novel strategies for overcoming this problem is crucial. Numerous studies demonstrated that cerebral edema may be attenuated via the regulation of AQP4 expression, thus initiating a novel therapeutic strategy against this possibly fatal condition. This review focuses on the role of AQP4 in ischemic brain edema, and its prospect as a therapeutic target.
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Affiliation(s)
- Wen-Wen Wang
- The Center of Traditional Chinese Medicine, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou 325027, China
| | - Cheng-long Xie
- Department of Neurology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou 325027, China
| | - Li-Li Zhou
- Department of Neurology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou 325027, China
| | - Guo-Sheng Wang
- Department of Oncology, The First Affiliated Hospital Beilun Branch of Zhejiang University, College of Medicine, Ningbo 315806, China.
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40
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Goodnough CL, Gao Y, Li X, Qutaish MQ, Goodnough LH, Molter J, Wilson D, Flask CA, Yu X. Lack of dystrophin results in abnormal cerebral diffusion and perfusion in vivo. Neuroimage 2014; 102 Pt 2:809-16. [PMID: 25213753 PMCID: PMC4320943 DOI: 10.1016/j.neuroimage.2014.08.053] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 08/25/2014] [Accepted: 08/29/2014] [Indexed: 01/08/2023] Open
Abstract
Dystrophin, the main component of the dystrophin–glycoprotein complex, plays an important role in maintaining the structural integrity of cells. It is also involved in the formation of the blood–brain barrier (BBB). To elucidate the impact of dystrophin disruption in vivo, we characterized changes in cerebral perfusion and diffusion in dystrophin-deficient mice (mdx) by magnetic resonance imaging (MRI). Arterial spin labeling (ASL) and diffusion-weighted MRI (DWI) studies were performed on 2-month-old and 10-month-old mdx mice and their age-matched wild-type controls (WT). The imaging results were correlated with Evan's blue extravasation and vascular density studies. The results show that dystrophin disruption significantly decreased the mean cerebral diffusivity in both 2-month-old (7.38± 0.30 × 10−4mm2/s) and 10-month-old (6.93 ± 0.53 × 10−4 mm2/s) mdx mice as compared to WT (8.49±0.24×10−4, 8.24±0.25× 10−4mm2/s, respectively). There was also an 18% decrease in cerebral perfusion in 10-month-old mdx mice as compared to WT, which was associated with enhanced arteriogenesis. The reduction in water diffusivity in mdx mice is likely due to an increase in cerebral edema or the existence of large molecules in the extracellular space from a leaky BBB. The observation of decreased perfusion in the setting of enhanced arteriogenesis may be caused by an increase of intracranial pressure from cerebral edema. This study demonstrates the defects in water handling at the BBB and consequently, abnormal perfusion associated with the absence of dystrophin.
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Affiliation(s)
- Candida L Goodnough
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ying Gao
- Department of Radiology, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Xin Li
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Mohammed Q Qutaish
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - L Henry Goodnough
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Joseph Molter
- Department of Radiology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - David Wilson
- Department of Radiology, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Chris A Flask
- Department of Radiology, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Pediatrics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Xin Yu
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Radiology, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
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41
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Stokum JA, Kurland DB, Gerzanich V, Simard JM. Mechanisms of astrocyte-mediated cerebral edema. Neurochem Res 2014; 40:317-28. [PMID: 24996934 DOI: 10.1007/s11064-014-1374-3] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 06/18/2014] [Accepted: 06/26/2014] [Indexed: 11/26/2022]
Abstract
Cerebral edema formation stems from disruption of blood brain barrier (BBB) integrity and occurs after injury to the CNS. Due to the restrictive skull, relatively small increases in brain volume can translate into impaired tissue perfusion and brain herniation. In excess, cerebral edema can be gravely harmful. Astrocytes are key participants in cerebral edema by virtue of their relationship with the cerebral vasculature, their unique compliment of solute and water transport proteins, and their general role in brain volume homeostasis. Following the discovery of aquaporins, passive conduits of water flow, aquaporin 4 (AQP4) was identified as the predominant astrocyte water channel. Normally, AQP4 is highly enriched at perivascular endfeet, the outermost layer of the BBB, whereas after injury, AQP4 expression disseminates to the entire astrocytic plasmalemma, a phenomenon termed dysregulation. Arguably, the most important role of AQP4 is to rapidly neutralize osmotic gradients generated by ionic transporters. In pathological conditions, AQP4 is believed to be intimately involved in the formation and clearance of cerebral edema. In this review, we discuss aquaporin function and localization in the BBB during health and injury, and we examine post-injury ionic events that modulate AQP4-dependent edema formation.
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Affiliation(s)
- Jesse A Stokum
- Department of Neurosurgery, University of Maryland School of Medicine, 22 S. Greene St., Suite S12D, Baltimore, MD, 21201-1595, USA
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Huang J, Lu WT, Sun SQ, Yang ZB, Huang SQ, Gan SW, Xu J, Qiu GP, Zhuo F, Zhu SJ, Jiang J, Jiang XL. Upregulation and lysosomal degradation of AQP4 in rat brains with bacterial meningitis. Neurosci Lett 2014; 566:156-61. [PMID: 24602980 DOI: 10.1016/j.neulet.2014.02.054] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Revised: 02/15/2014] [Accepted: 02/25/2014] [Indexed: 11/20/2022]
Abstract
Brain edema is among the major complications in children with bacterial meningitis. Aquaporins are integral membrane pore proteins that form channels to regulate cellular water content. Aquaporin-4 (AQP4), which is enriched in parts of astrocytic membranes that are apposed to pial or perivascular basal laminae, is the predominant aquaporin in the central nervous system. Dystroglycan is among the proteins that are responsible for the site-specific anchorage of AQP4. To elucidate the role of AQP4 in the development of brain edema induced by meningitis, a model of bacterial meningitis was established by injecting group B β-hemolytic Streptococci into the cerebrospinal fluid of three-week-old rats. The brain water content increased in this model compared with that in the control group. The expression of AQP4 and dystroglycan was examined by Western blot and the degradation route of AQP4 was investigated by double immunofluorescence labeling. Western blot results showed that the expression of AQP4 and dystroglycan in rat brain increased in the meningitis model. Meanwhile, AQP4 was co-localized with the marker of lysosome in this model, indicating that the lysosome is involved in AQP4 degradation.
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Affiliation(s)
- Juan Huang
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, People's Republic of China
| | - Wei Tian Lu
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, People's Republic of China
| | - Shan Quan Sun
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, People's Republic of China.
| | - Zhi Bang Yang
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, People's Republic of China
| | - Si Qin Huang
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, People's Republic of China
| | - Sheng Wei Gan
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, People's Republic of China
| | - Jin Xu
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, People's Republic of China
| | - Guo Ping Qiu
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, People's Republic of China
| | - Fei Zhuo
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, People's Republic of China
| | - Shu Juan Zhu
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, People's Republic of China
| | - Jin Jiang
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, People's Republic of China
| | - Xu Li Jiang
- Institute of Neuroscience, Chongqing Medical University, Chongqing 400016, People's Republic of China
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Lunde LK, Camassa LMA, Hoddevik EH, Khan FH, Ottersen OP, Boldt HB, Amiry-Moghaddam M. Postnatal development of the molecular complex underlying astrocyte polarization. Brain Struct Funct 2014; 220:2087-101. [PMID: 24777283 PMCID: PMC4481305 DOI: 10.1007/s00429-014-0775-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 04/04/2014] [Indexed: 11/29/2022]
Abstract
Astrocytes are highly polarised cells with processes that ensheath microvessels, cover the brain surface, and abut synapses. The endfoot membrane domains facing microvessels and pia are enriched with aquaporin-4 water channels (AQP4) and other members of the dystrophin associated protein complex (DAPC). Several lines of evidence show that loss of astrocyte polarization, defined by the loss of proteins that are normally enriched in astrocyte endfeet, is a common denominator of several neurological diseases such as mesial temporal lobe epilepsy, Alzheimer's disease, and stroke. Little is known about the mechanisms responsible for inducing astrocyte polarization in vivo. Here we introduce the term endfoot-basal lamina junctional complex (EBJC) to denote the proteins that consolidate and characterize the gliovascular interface. The present study was initiated in order to resolve the developmental profile of the EBJC in mouse brain. We show that the EBJC is established after the first week postnatally. Through a combination of methodological approaches, including light microscopic and high resolution immunogold cytochemistry, quantitative RT-PCR, and Western blotting, we demonstrate that the different members of this complex exhibit distinct ontogenic profiles—with the extracellular matrix (ECM) proteins laminin and agrin appearing earlier than the other members of the complex. Specifically, while laminin and agrin expression peak at P7, quantitative immunoblot analyses indicate that AQP4, α-syntrophin, and the inwardly rectifying K(+) channel Kir4.1 expression increases towards adulthood. Our findings are consistent with ECM having an instructive role in establishing astrocyte polarization in postnatal development and emphasize the need to explore the involvement of ECM in neurological disease.
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Affiliation(s)
- Lisa K Lunde
- Laboratory of Molecular Neuroscience, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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Wakayama Y, Hirako S, Ogawa T, Jimi T, Shioda S. Upregulated Expression of AQP 7 in the Skeletal Muscles of Obese ob/ob Mice. Acta Histochem Cytochem 2014; 47:27-33. [PMID: 24761047 PMCID: PMC3972427 DOI: 10.1267/ahc.13032] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 02/04/2014] [Indexed: 02/03/2023] Open
Abstract
Aquaporin (AQP) is suggested to be regulated by leptin through the phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin pathway. AQP7 and AQP9 are membrane proteins with water and glycerol channels, the latter of which is essential for triglyceride synthesis. We conjectured that the expression of AQP7 and AQP9 would be altered in the skeletal myofibers in obese leptin deficient ob/ob mice as compared with that of wild mice. RNA and protein levels were studied in the quadriceps femoris muscles of ob/ob and wild mice. Real time quantitative RT-PCR analysis showed that mouse AQP7 mRNA levels in skeletal muscles were significantly higher in ob/ob mice than in wild mice (P<0.01), whereas mouse AQP9 mRNA level was not different between the two groups (P>0.05). Histologically the type 1 myofibers of ob/ob mice contained numerous lipid droplets in oil red O stain samples. Immunohistochemical staining of ob/ob mouse muscles revealed enhanced expression of AQP7 at myofiber surface membranes, while AQP9 expression appeared to be similar to that of wild mice. The findings suggest that the upregulated expression of AQP7 in ob/ob mouse muscles facilitates the secretion of glycerol from myocytes.
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Affiliation(s)
- Yoshihiro Wakayama
- Wakayama Clinic
- Department of Anatomy, Showa University School of Medicine
| | - Satoshi Hirako
- Department of Anatomy, Showa University School of Medicine
| | - Tetsuo Ogawa
- Department of Anatomy, Showa University School of Medicine
| | | | - Seiji Shioda
- Department of Anatomy, Showa University School of Medicine
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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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Abstract
Aquaporins are a group of proteins with high-selective permeability for water. A subgroup called aquaglyceroporins is also permeable to glycerol, urea and a few other solutes. Aquaporin function has mainly been studied in the brain, kidney, glands and skeletal muscle, while the information about aquaporins in the heart is still scarce. The current review explores the recent advances in this field, bringing aquaporins into focus in the context of myocardial ischemia, reperfusion, and blood osmolarity disturbances. Since the amount of data on aquaporins in the heart is still limited, examples and comparisons from better-studied areas of aquaporin biology have been used. The human heart expresses aquaporin-1, -3, -4 and -7 at the protein level. The potential roles of aquaporins in the heart are discussed, and some general phenomena that the myocardial aquaporins share with aquaporins in other organs are elaborated. Cardiac aquaporin-1 is mostly distributed in the microvasculature. Its main role is transcellular water flux across the endothelial membranes. Aquaporin-4 is expressed in myocytes, both in cardiac and in skeletal muscle. In addition to water flux, its function is connected to the calcium signaling machinery. It may play a role in ischemia-reperfusion injury. Aquaglyceroporins, especially aquaporin-7, may serve as a novel pathway for nutrient delivery into the heart. They also mediate toxicity of various poisons. Aquaporins cannot influence permeability by gating, therefore, their function is regulated by changes of expression-on the levels of transcription, translation (by microRNAs), post-translational modification, membrane trafficking, ubiquitination and subsequent degradation. Studies using mice genetically deficient for aquaporins have shown rather modest changes in the heart. However, they might still prove to be attractive targets for therapy directed to reduce myocardial edema and injury caused by ischemia and reperfusion.
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Alvarez JI, Katayama T, Prat A. Glial influence on the blood brain barrier. Glia 2013; 61:1939-58. [PMID: 24123158 PMCID: PMC4068281 DOI: 10.1002/glia.22575] [Citation(s) in RCA: 380] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 08/13/2013] [Accepted: 08/19/2013] [Indexed: 12/14/2022]
Abstract
The Blood Brain Barrier (BBB) is a specialized vascular structure tightly regulating central nervous system (CNS) homeostasis. Endothelial cells are the central component of the BBB and control of their barrier phenotype resides on astrocytes and pericytes. Interactions between these cells and the endothelium promote and maintain many of the physiological and metabolic characteristics that are unique to the BBB. In this review we describe recent findings related to the involvement of astroglial cells, including radial glial cells, in the induction of barrier properties during embryogenesis and adulthood. In addition, we describe changes that occur in astrocytes and endothelial cells during injury and inflammation with a particular emphasis on alterations of the BBB phenotype. GLIA 2013;61:1939–1958
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Affiliation(s)
- Jorge Ivan Alvarez
- Neuroimmunology unit, Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montréal, Québec, Canada
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Gundersen GA, Vindedal GF, Skare O, Nagelhus EA. Evidence that pericytes regulate aquaporin-4 polarization in mouse cortical astrocytes. Brain Struct Funct 2013; 219:2181-6. [PMID: 23982198 PMCID: PMC4223569 DOI: 10.1007/s00429-013-0629-0] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Accepted: 08/16/2013] [Indexed: 11/29/2022]
Abstract
Aquaporin-4 (AQP4) water channels are concentrated in astrocytic endfoot membranes at the brain–blood and brain–cerebrospinal fluid interfaces. The mechanisms underpinning the polarized distribution of AQP4 are poorly understood. Here we tested the hypothesis that pericytes regulate AQP4 anchoring to perivascular astrocytic endfoot membranes. AQP4 immunofluorescence of brain sections obtained from novel transgenic double reporter mice expressing enhanced green fluorescent protein (eGFP) in astrocytes and Discoma Red (DsRed) in pericytes revealed strong AQP4 signal in astrocytic processes adjacent to pericytes. Quantitative immunogold analysis of C57BL/6 mice showed that the AQP4 expression was higher in endfoot membranes abutting pericytes than in those facing endothelial cells. Similar findings were made for α-syntrophin, a member of the dystrophin-associated protein complex (DAPC). The enrichment of α-syntrophin in membranes ensheathing pericytes persisted after Aqp4 gene deletion. Our data support the concept that pericytes regulate AQP4 polarization.
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Affiliation(s)
- Georg Andreas Gundersen
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, P.O. Box 1137, Blindern, 0318, Oslo, Norway
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Iliff JJ, Wang M, Liao Y, Plogg BA, Peng W, Gundersen GA, Benveniste H, Vates GE, Deane R, Goldman SA, Nagelhus EA, Nedergaard M. A paravascular pathway facilitates CSF flow through the brain parenchyma and the clearance of interstitial solutes, including amyloid β. Sci Transl Med 2013; 4:147ra111. [PMID: 22896675 DOI: 10.1126/scitranslmed.3003748] [Citation(s) in RCA: 3167] [Impact Index Per Article: 287.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Because it lacks a lymphatic circulation, the brain must clear extracellular proteins by an alternative mechanism. The cerebrospinal fluid (CSF) functions as a sink for brain extracellular solutes, but it is not clear how solutes from the brain interstitium move from the parenchyma to the CSF. We demonstrate that a substantial portion of subarachnoid CSF cycles through the brain interstitial space. On the basis of in vivo two-photon imaging of small fluorescent tracers, we showed that CSF enters the parenchyma along paravascular spaces that surround penetrating arteries and that brain interstitial fluid is cleared along paravenous drainage pathways. Animals lacking the water channel aquaporin-4 (AQP4) in astrocytes exhibit slowed CSF influx through this system and a ~70% reduction in interstitial solute clearance, suggesting that the bulk fluid flow between these anatomical influx and efflux routes is supported by astrocytic water transport. Fluorescent-tagged amyloid β, a peptide thought to be pathogenic in Alzheimer's disease, was transported along this route, and deletion of the Aqp4 gene suppressed the clearance of soluble amyloid β, suggesting that this pathway may remove amyloid β from the central nervous system. Clearance through paravenous flow may also regulate extracellular levels of proteins involved with neurodegenerative conditions, its impairment perhaps contributing to the mis-accumulation of soluble proteins.
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Affiliation(s)
- Jeffrey J Iliff
- Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY 14642, USA.
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