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Chen J, Yang J, Chu J, Chen KH, Alt J, Rais R, Qiu Z. The SWELL1 Channel Promotes Ischemic Brain Damage by Mediating Neuronal Swelling and Glutamate Toxicity. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2401085. [PMID: 39056405 DOI: 10.1002/advs.202401085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 07/15/2024] [Indexed: 07/28/2024]
Abstract
Cytotoxic neuronal swelling and glutamate excitotoxicity are two hallmarks of ischemic stroke. However, the underlying molecular mechanisms are not well understood. Here, it is reported that SWELL1, the essential subunit of the volume-regulated anion channel (VRAC), plays a dual role in ischemic injury by promoting neuronal swelling and glutamate excitotoxicity. SWELL1 expression is upregulated in neurons and astrocytes after experimental stroke in mice. The neuronal SWELL1 channel is activated by intracellular hypertonicity, leading to Cl- influx-dependent cytotoxic neuronal swelling and subsequent cell death. Additionally, the SWELL1 channel in astrocytes mediates pathological glutamate release, indicated by increases in neuronal slow inward current frequency and tonic NMDAR current. Pharmacologically, targeting VRAC with a new inhibitor, an FDA-approved drug Dicumarol, attenuated cytotoxic neuronal swelling and cell death, reduced astrocytic glutamate release, and provided significant neuroprotection in mice when administered either before or after ischemia. Therefore, these findings uncover the pleiotropic effects of the SWELL1 channel in neurons and astrocytes in the pathogenesis of ischemic stroke and provide proof of concept for therapeutically targeting it in this disease.
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Affiliation(s)
- Jianan Chen
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Nanozyme Medical Center, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001, China
| | - Junhua Yang
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Department of Veterinary Integrative Biosciences, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas, TX, 77843, USA
| | - Jiachen Chu
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Kevin Hong Chen
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Jesse Alt
- Johns Hopkins Drug Discovery, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Rana Rais
- Johns Hopkins Drug Discovery, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Zhaozhu Qiu
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
- Solomon H. Snyder Department of Neuroscience, Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
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Salgado M, Márquez-Miranda V, Ferrada L, Rojas M, Poblete-Flores G, González-Nilo FD, Ardiles ÁO, Sáez JC. Ca 2+ permeation through C-terminal cleaved, but not full-length human Pannexin1 hemichannels, mediates cell death. Proc Natl Acad Sci U S A 2024; 121:e2405468121. [PMID: 38861601 PMCID: PMC11194574 DOI: 10.1073/pnas.2405468121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Accepted: 05/10/2024] [Indexed: 06/13/2024] Open
Abstract
Pannexin1 hemichannels (Panx1 HCs) are found in the membrane of most mammalian cells and communicate the intracellular and extracellular spaces, enabling the passive transfer of ions and small molecules. They are involved in physiological and pathophysiological conditions. During apoptosis, the C-terminal tail of Panx1 is proteolytically cleaved, but the permeability features of hemichannels and their role in cell death remain elusive. To address these topics, HeLa cells transfected with full-length human Panx1 (fl-hPanx1) or C-terminal truncated hPanx1 (Δ371hPanx1) were exposed to alkaline extracellular saline solution, increasing the activity of Panx1 HCs. The Δ371hPanx1 HC was permeable to DAPI and Etd+, but not to propidium iodide, whereas fl-hPanx1 HC was only permeable to DAPI. Furthermore, the cytoplasmic Ca2+ signal increased only in Δ371hPanx1 cells, which was supported by bioinformatics approaches. The influx of Ca2+ through Δ371hPanx1 HCs was necessary to promote cell death up to about 95% of cells, whereas the exposure to alkaline saline solution without Ca2+ failed to induce cell death, and the Ca2+ ionophore A23187 promoted more than 80% cell death even in fl-hPanx1 transfectants. Moreover, cell death was prevented with carbenoxolone or 10Panx1 in Δ371hPanx1 cells, whereas it was undetectable in HeLa Panx1-/- cells. Pretreatment with Ferrostatin-1 and necrostatin-1 did not prevent cell death, suggesting that ferroptosis or necroptosis was not involved. In comparison, zVAD-FMK, a pancaspase inhibitor, reduced death by ~60%, suggesting the involvement of apoptosis. Therefore, alkaline pH increases the activity of Δ371hPanx1HCs, leading to a critical intracellular free-Ca2+ overload that promotes cell death.
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Affiliation(s)
- Magdiel Salgado
- Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias, Universidad de Valparaíso, Valparaíso2381850, Chile
| | - Valeria Márquez-Miranda
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago8370146, Chile
| | - Luciano Ferrada
- Centro de Microscopía Avanzada-Biobío, Universidad de Concepción, Concepción4070386, Chile
| | - Maximiliano Rojas
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago8370146, Chile
| | - Gonzalo Poblete-Flores
- Escuela de Medicina, Facultad de Medicina, Universidad de Valparaíso, Valparaíso2341386, Chile
| | - Fernando D. González-Nilo
- Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias, Universidad de Valparaíso, Valparaíso2381850, Chile
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago8370146, Chile
| | - Álvaro O. Ardiles
- Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias, Universidad de Valparaíso, Valparaíso2381850, Chile
- Escuela de Medicina, Facultad de Medicina, Universidad de Valparaíso, Valparaíso2341386, Chile
| | - Juan C. Sáez
- Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias, Universidad de Valparaíso, Valparaíso2381850, Chile
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Bayraktar E, Lopez-Pigozzi D, Bortolozzi M. Calcium Regulation of Connexin Hemichannels. Int J Mol Sci 2024; 25:6594. [PMID: 38928300 PMCID: PMC11204158 DOI: 10.3390/ijms25126594] [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: 05/01/2024] [Revised: 06/07/2024] [Accepted: 06/12/2024] [Indexed: 06/28/2024] Open
Abstract
Connexin hemichannels (HCs) expressed at the plasma membrane of mammalian cells are of paramount importance for intercellular communication. In physiological conditions, HCs can form gap junction (GJ) channels, providing a direct diffusive path between neighbouring cells. In addition, unpaired HCs provide conduits for the exchange of solutes between the cytoplasm and the extracellular milieu, including messenger molecules involved in paracrine signalling. The synergistic action of membrane potential and Ca2+ ions controls the gating of the large and relatively unselective pore of connexin HCs. The four orders of magnitude difference in gating sensitivity to the extracellular ([Ca2+]e) and the cytosolic ([Ca2+]c) Ca2+ concentrations suggests that at least two different Ca2+ sensors may exist. While [Ca2+]e acts as a spatial modulator of the HC opening, which is most likely dependent on the cell layer, compartment, and organ, [Ca2+]c triggers HC opening and the release of extracellular bursts of messenger molecules. Such molecules include ATP, cAMP, glutamate, NAD+, glutathione, D-serine, and prostaglandins. Lost or abnormal HC regulation by Ca2+ has been associated with several diseases, including deafness, keratitis ichthyosis, palmoplantar keratoderma, Charcot-Marie-Tooth neuropathy, oculodentodigital dysplasia, and congenital cataracts. The fact that both an increased and a decreased Ca2+ sensitivity has been linked to pathological conditions suggests that Ca2+ in healthy cells finely tunes the normal HC function. Overall, further investigation is needed to clarify the structural and chemical modifications of connexin HCs during [Ca2+]e and [Ca2+]c variations. A molecular model that accounts for changes in both Ca2+ and the transmembrane voltage will undoubtedly enhance our interpretation of the experimental results and pave the way for developing therapeutic compounds targeting specific HC dysfunctions.
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Affiliation(s)
- Erva Bayraktar
- Veneto Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Via Marzolo 8, 35131 Padova, Italy
| | - Diego Lopez-Pigozzi
- Veneto Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Via Marzolo 8, 35131 Padova, Italy
| | - Mario Bortolozzi
- Veneto Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Via Marzolo 8, 35131 Padova, Italy
- Institute of Endocrinology and Oncology “Gaetano Salvatore” (IEOS-CNR), Via Pietro Castellino 111, 80131 Napoli, Italy
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Schlaeger L, Olejniczak I, Lehmann M, Schmidt CX, Astiz M, Oster H, Pilorz V. Estrogen-mediated coupling via gap junctions in the suprachiasmatic nucleus. Eur J Neurosci 2024; 59:1723-1742. [PMID: 38326974 DOI: 10.1111/ejn.16270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 01/11/2024] [Accepted: 01/22/2024] [Indexed: 02/09/2024]
Abstract
The circadian clock orchestrates many physiological and behavioural rhythms in mammals with 24-h periodicity, through a hierarchical organisation, with the central clock located in the suprachiasmatic nucleus (SCN) in the hypothalamus. The circuits of the SCN generate circadian rhythms with precision, relying on intrinsic coupling mechanisms, for example, neurotransmitters like arginine vasopressin (AVP), vasoactive intestinal peptide (VIP), neuronal gamma-aminobutyric acid (GABA) signalling and astrocytes connected by gap junctions composed of connexins (Cx). In female rodents, the presence of estrogen receptors (ERs) in the dorsal SCN suggests an influence of estrogen (E2) on the circuit timekeeping that could regulate circadian rhythm and coupling. To investigate this, we used SCN explants together with hypothalamic neurons and astrocytes. First, we showed that E2 stabilised the circadian amplitude in the SCN when rAVPs (receptor-associated vasopressin peptides) were inhibited. However, the phase delay induced by VIPAC2 (VIP receptors) inhibition remained unaffected by E2. We then showed that E2 exerted its effects in the SCN via ERβ (estrogen receptor beta), resulting in increased expression of Cx36 and Cx43. Notably, specific inhibition of both connexins resulted in a significant reduction in circadian amplitude within the SCN. Remarkably, E2 restored the period with inhibited Cx36 but not with Cx43 inhibition. This implies that the network between astrocytes and neurons, responsible for coupling in the SCN, can be reinforced through E2. In conclusion, these findings provide new insights into how E2 regulates circadian rhythms ex vivo in an ERβ-dependent manner, underscoring its crucial role in fortifying the SCN's rhythm.
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Affiliation(s)
- Lina Schlaeger
- Institute of Neurobiology, Center of Brain, Behaviour and Metabolism, Marie-Curie-Strasse, University of Lübeck, Lübeck, Germany
| | - Iwona Olejniczak
- Institute of Neurobiology, Center of Brain, Behaviour and Metabolism, Marie-Curie-Strasse, University of Lübeck, Lübeck, Germany
| | - Marianne Lehmann
- Institute of Neurobiology, Center of Brain, Behaviour and Metabolism, Marie-Curie-Strasse, University of Lübeck, Lübeck, Germany
| | - Cosima Xenia Schmidt
- Institute of Neurobiology, Center of Brain, Behaviour and Metabolism, Marie-Curie-Strasse, University of Lübeck, Lübeck, Germany
| | - Mariana Astiz
- Institute of Neurobiology, Center of Brain, Behaviour and Metabolism, Marie-Curie-Strasse, University of Lübeck, Lübeck, Germany
- Achucarro Basque Center for Neuroscience, Leioa, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Henrik Oster
- Institute of Neurobiology, Center of Brain, Behaviour and Metabolism, Marie-Curie-Strasse, University of Lübeck, Lübeck, Germany
| | - Violetta Pilorz
- Institute of Neurobiology, Center of Brain, Behaviour and Metabolism, Marie-Curie-Strasse, University of Lübeck, Lübeck, Germany
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Mishima T, Komano K, Tabaru M, Kofuji T, Saito A, Ugawa Y, Terao Y. Repetitive pulsed-wave ultrasound stimulation suppresses neural activity by modulating ambient GABA levels via effects on astrocytes. Front Cell Neurosci 2024; 18:1361242. [PMID: 38601023 PMCID: PMC11004293 DOI: 10.3389/fncel.2024.1361242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Accepted: 03/18/2024] [Indexed: 04/12/2024] Open
Abstract
Ultrasound is highly biopermeable and can non-invasively penetrate deep into the brain. Stimulation with patterned low-intensity ultrasound can induce sustained inhibition of neural activity in humans and animals, with potential implications for research and therapeutics. Although mechanosensitive channels are involved, the cellular and molecular mechanisms underlying neuromodulation by ultrasound remain unknown. To investigate the mechanism of action of ultrasound stimulation, we studied the effects of two types of patterned ultrasound on synaptic transmission and neural network activity using whole-cell recordings in primary cultured hippocampal cells. Single-shot pulsed-wave (PW) or continuous-wave (CW) ultrasound had no effect on neural activity. By contrast, although repetitive CW stimulation also had no effect, repetitive PW stimulation persistently reduced spontaneous recurrent burst firing. This inhibitory effect was dependent on extrasynaptic-but not synaptic-GABAA receptors, and the effect was abolished under astrocyte-free conditions. Pharmacological activation of astrocytic TRPA1 channels mimicked the effects of ultrasound by increasing the tonic GABAA current induced by ambient GABA. Pharmacological blockade of TRPA1 channels abolished the inhibitory effect of ultrasound. These findings suggest that the repetitive PW low-intensity ultrasound used in our study does not have a direct effect on neural function but instead exerts its sustained neuromodulatory effect through modulation of ambient GABA levels via channels with characteristics of TRPA1, which is expressed in astrocytes.
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Affiliation(s)
- Tatsuya Mishima
- Department of Medical Physiology, Kyorin University School of Medicine, Mitaka, Japan
| | - Kenta Komano
- Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Marie Tabaru
- Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Takefumi Kofuji
- Department of Medical Physiology, Kyorin University School of Medicine, Mitaka, Japan
- Radioisotope Laboratory, Kyorin University School of Medicine, Mitaka, Japan
| | - Ayako Saito
- Department of Medical Physiology, Kyorin University School of Medicine, Mitaka, Japan
| | - Yoshikazu Ugawa
- Department of Human Neurophysiology, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Yasuo Terao
- Department of Medical Physiology, Kyorin University School of Medicine, Mitaka, Japan
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6
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McDouall A, Wassink G, Ranasinghe S, Zhou KQ, Karunasinghe RN, Dean JM, Davidson JO. Blockade of connexin hemichannels with tonabersat protects against mild hypoxic ischemic brain injury in neonatal rats. Exp Neurol 2024; 371:114611. [PMID: 37944882 DOI: 10.1016/j.expneurol.2023.114611] [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: 07/30/2023] [Revised: 10/15/2023] [Accepted: 11/06/2023] [Indexed: 11/12/2023]
Abstract
BACKGROUND AND PURPOSE There is growing evidence that infants with mild hypoxic-ischemic (HI) encephalopathy have increased risk of brain injury and adverse neurodevelopmental outcomes. Currently, there is no approved treatment for these infants. It was previously shown that blocking connexin 43 hemichannels is neuroprotective in models of moderate to severe HI injury. However, it is yet to be established whether these channels play a role in the evolution of mild HI brain injury, and whether blocking these channels after mild HI is neuroprotective. METHODS HI was induced in postnatal day 10 rats of both sexes by right carotid artery ligation followed by 80 min of hypoxia in 8% oxygen. Pups receiving HI were randomised to receive intraperitoneal injections of either saline, vehicle (2-hydroxypropyl-beta-cyclodextrin polyethylene glycol-400), or tonabersat (2 mg/kg), at 60 min, 24 h, and 48 h after hypoxia. Seven days after HI, brains were harvested for measurement of volume loss and histological analysis. RESULTS HI resulted in a significant reduction in hemispheric, hippocampal, and white matter volumes, which were significantly attenuated after treatment with tonabersat. HI was also associated with a significant reduction in numbers of neurons in the CA1 and CA3 hippocampal regions, a reduction in the numbers of oligodendrocytes in the corpus callosum, and an increase in the number of astrocytes in both regions, which were significantly attenuated by tonabersat treatment. There were no differences in rectal temperatures between tonabersat- and vehicle-treated rat pups. CONCLUSIONS Blockade of connexin hemichannels with tonabersat significantly reduced mild HI injury in the hippocampus and white matter, without causing hypothermia.
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Affiliation(s)
- Alice McDouall
- Department of Physiology, the University of Auckland, New Zealand
| | - Guido Wassink
- Department of Physiology, the University of Auckland, New Zealand
| | | | - Kelly Q Zhou
- Department of Physiology, the University of Auckland, New Zealand
| | | | - Justin M Dean
- Department of Physiology, the University of Auckland, New Zealand
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Bayraktar E, Bortolozzi M. Measuring Connexin Hemichannel Opening in Response to an InsP3-Mediated Cytosolic Ca 2+ Increase. Methods Mol Biol 2024; 2801:189-197. [PMID: 38578422 DOI: 10.1007/978-1-0716-3842-2_14] [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] [Indexed: 04/06/2024]
Abstract
The opening of connexin hemichannels (HCs) expressed at the plasma membrane of mammalian cells is regulated by a number of physiological parameters, including extracellular and intracellular Ca2+ ions. Submicromolar variations of the cytosolic Ca2+ concentration ([Ca2+]c) are per se sufficient to trigger extracellular bursts of messenger molecules through connexin HCs, thus mediating paracrine signaling. In this chapter, we present a quantitative method to measure the opening dynamics of connexin HCs expressed in a single HeLa cell upon stimulation by a canonical InsP3-mediated [Ca2+]c transient. The protocol relies on a combination of Ca2+ imaging and patch-clamp techniques. The insights gained from our method are expected to make a significant contribution to understanding the structure-function relationship of connexin HCs. The protocol is also suitable to screen candidate therapeutic compounds to treat connexin-related diseases linked to HC dysfunction.
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Affiliation(s)
- Erva Bayraktar
- Department of Physics and Astronomy "G. Galilei", University of Padua, Padova, Italy
- Veneto Institute of Molecular Medicine (VIMM), Padova, Italy
| | - Mario Bortolozzi
- Department of Physics and Astronomy "G. Galilei", University of Padua, Padova, Italy.
- Veneto Institute of Molecular Medicine (VIMM), Padova, Italy.
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8
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Schumacher S, Tahiri H, Ezan P, Rouach N, Witschas K, Leybaert L. Inhibiting astrocyte connexin-43 hemichannels blocks radiation-induced vesicular VEGF-A release and blood-brain barrier dysfunction. Glia 2024; 72:34-50. [PMID: 37670489 DOI: 10.1002/glia.24460] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 07/28/2023] [Accepted: 08/09/2023] [Indexed: 09/07/2023]
Abstract
Therapeutic brain irradiation with ionizing radiation exerts multiple side effects including barrier leakage that disturbs glial-neuronal functioning and may affect cognition. Astrocytes contribute to barrier leakage by endfeet release of various vasoactive substances acting on capillary endothelial cells forming the barrier. Here, we investigated X-ray effects on astrocytic vesicular transport in mice and determined whether interfering with astrocyte connexins affects radiation-induced barrier leakage. We found that astrocytic VEGF-A-loaded VAMP3 vesicles drastically reorganize starting from 6 h post-irradiation and move in a calcium- and Cx43-dependent manner towards endfeet where VEGF-A is released, provoking barrier leakage. Vesicular transport activation, VEGF-A release and leakage 24 h post-irradiation were all potently inhibited by astrocytic Cx43 KO, Cx43S255/262/279/282A (MK4) mutant mice and TATGap19 inhibition of Cx43 hemichannel opening. Astrocyte VEGF release is a major player in complications of brain irradiation, which can be mitigated by anti-VEGF treatments. Targeting Cx43 hemichannels allows to prevent astrocyte VEGF release at an early stage after brain irradiation.
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Affiliation(s)
- Steffi Schumacher
- Department of Basic and Applied Medical Sciences - Physiology Group, Ghent University, Ghent, Belgium
| | - Hanane Tahiri
- Department of Basic and Applied Medical Sciences - Physiology Group, Ghent University, Ghent, Belgium
| | - Pascal Ezan
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS, INSERM, Université PSL, Labex Memolife, Paris, France
| | - Nathalie Rouach
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS, INSERM, Université PSL, Labex Memolife, Paris, France
| | - Katja Witschas
- Department of Basic and Applied Medical Sciences - Physiology Group, Ghent University, Ghent, Belgium
| | - Luc Leybaert
- Department of Basic and Applied Medical Sciences - Physiology Group, Ghent University, Ghent, Belgium
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Zielewicz LJ, Wang J, Ndaru E, Maney B, Yu X, Albers T, Grewer C. Design and Characterization of Prodrug-like Inhibitors for Preventing Glutamate Efflux through Reverse Transport. ACS Chem Neurosci 2023; 14:4252-4263. [PMID: 37994790 DOI: 10.1021/acschemneuro.3c00651] [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] [Indexed: 11/24/2023] Open
Abstract
Glutamate transporters are responsible for active transport of the major excitatory neurotransmitter glutamate across the cell membrane, regulating the extracellular glutamate concentration in the mammalian brain. Extracellular glutamate levels in the brain are usually in the submicromolar range but can increase by exocytosis, inhibition of cellular uptake, or through glutamate release by reverse transport, as well as other mechanisms, which can lead to neurodegeneration and neuronal cell death. Such conditions can be encountered upon energy deprivation during an ischemic stroke. Here, we developed acetoxymethyl (AM) ester prodrug-like derivatives of excitatory amino acid transporter (EAAT) inhibitors that permeate the cell membrane and are activated, most likely through hydrolysis by endogenous cellular esterases, to form the active EAAT inhibitor. Upon increase in external K+ concentration, the inhibitors block glutamate efflux by EAAT reverse transport. Using a novel high-affinity fluorescent prodrug-like inhibitor, dl-threo-9-anthracene-methoxy-aspartate (TAOA) AM ester, we demonstrate that the precursor rapidly accumulates inside cells. Electrophysiological methods and fluorescence assays utilizing the iGluSnFR external glutamate sensor were used to demonstrate the efficacy of AM ester-protected inhibitors in inhibiting K+-mediated glutamate release. Together, our results provide evidence for a novel method to potentially prevent glutamate release by reverse transport under pathophysiological conditions in a model cell system, as well as in human astrocytes, while leaving glutamate uptake under physiological conditions operational. This method could have wide-ranging applications in the prevention of glutamate-induced neuronal cell death.
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Affiliation(s)
- Laura J Zielewicz
- Department of Chemistry, Binghamton University, 4400 Vestal Parkway East, Binghamton, New York 13902, United States
| | - Jiali Wang
- Department of Chemistry, Binghamton University, 4400 Vestal Parkway East, Binghamton, New York 13902, United States
| | - Elias Ndaru
- Department of Chemistry, Binghamton University, 4400 Vestal Parkway East, Binghamton, New York 13902, United States
| | - Brien Maney
- Department of Chemistry, Binghamton University, 4400 Vestal Parkway East, Binghamton, New York 13902, United States
| | - Xiaozhen Yu
- Department of Chemistry, Binghamton University, 4400 Vestal Parkway East, Binghamton, New York 13902, United States
| | - Thomas Albers
- Department of Chemistry, Binghamton University, 4400 Vestal Parkway East, Binghamton, New York 13902, United States
| | - Christof Grewer
- Department of Chemistry, Binghamton University, 4400 Vestal Parkway East, Binghamton, New York 13902, United States
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10
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Mezache L, Soltisz AM, Johnstone SR, Isakson BE, Veeraraghavan R. Vascular Endothelial Barrier Protection Prevents Atrial Fibrillation by Preserving Cardiac Nanostructure. JACC Clin Electrophysiol 2023; 9:2444-2458. [PMID: 38032579 PMCID: PMC11134328 DOI: 10.1016/j.jacep.2023.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 10/20/2023] [Accepted: 10/21/2023] [Indexed: 12/01/2023]
Abstract
BACKGROUND Atrial fibrillation (AF), the most common cardiac arrhythmia, is widely associated with inflammation, vascular dysfunction, and elevated levels of the vascular leak-inducing cytokine, vascular endothelial growth factor (VEGF). Mechanisms underlying AF are poorly understood and current treatments only manage this progressive disease, rather than arresting the underlying pathology. The authors previously identified edema-induced disruption of sodium channel (NaV1.5)-rich intercalated disk nanodomains as a novel mechanism for AF initiation secondary to acute inflammation. Therefore, we hypothesized that protecting the vascular barrier can prevent vascular leak-induced atrial arrhythmias. OBJECTIVES In this study the authors tested the hypothesis that protecting the vascular barrier can prevent vascular leak-induced atrial arrhythmias. They identified 2 molecular targets for vascular barrier protection, connexin43 (Cx43) hemichannels and pannexin-1 (Panx1) channels, which have been implicated in cytokine-induced vascular leak. METHODS The authors undertook in vivo electrocardiography, electron microscopy, and super-resolution light microscopy studies in mice acutely treated with a clinically relevant level of VEGF. RESULTS AF incidence was increased in untreated mice exposed to VEGF relative to vehicle control subjects. VEGF also increased the average number of AF episodes. VEGF shifted NaV1.5 signal to longer distances from Cx43 gap junctions, measured by a distance transformation-based spatial analysis of 3-dimensional confocal images of intercalated disks. Similar effects were observed with NaV1.5 localized near mechanical junctions composed of neural cadherin. Blocking connexin43 hemichannels (αCT11 peptide) or Panx1 channels (PxIL2P peptide) significantly reduced the duration of AF episodes compared with VEGF alone with no treatment. Concurrently, both peptide therapies preserved NaV1.5 distance from gap junctions to control levels and reduced mechanical junction-adjacent intermembrane distance in these hearts. Notably, similar antiarrhythmic efficacy was also achieved with clinically-relevant small-molecule inhibitors of Cx43 and Panx1. CONCLUSIONS These results highlight vascular barrier protection as an antiarrhythmic strategy following inflammation-induced vascular leak.
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Affiliation(s)
- Louisa Mezache
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Andrew M Soltisz
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Scott R Johnstone
- Fralin Biomedical Research Institute at VTC, Centre for Vascular and Heart Research, Virginia Tech, Roanoke, Virginia, USA; Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA; Virginia Tech Carilion School of Medicine, Department of Surgery, Roanoke, Virginia, USA
| | - Brant E Isakson
- Department of Molecular Physiology and Biological Physics, School of Medicine, University of Virginia, Charlottesville, Virginia, USA; Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Rengasayee Veeraraghavan
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, Ohio, USA; The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA; Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, Ohio, USA.
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11
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Ebrahimi M, Thompson P, Lauer AK, Sivaprasad S, Perry G. The retina-brain axis and diabetic retinopathy. Eur J Ophthalmol 2023; 33:2079-2095. [PMID: 37259525 DOI: 10.1177/11206721231172229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Diabetic retinopathy (DR) is a major contributor to permanent vision loss and blindness. Changes in retinal neurons, glia, and microvasculature have been the focus of intensive study in the quest to better understand DR. However, the impact of diabetes on the rest of the visual system has received less attention. There are reports of associations of changes in the visual system with preclinical and clinical manifestations of diabetes. Simultaneous investigation of the retina and the brain may shed light on the mechanisms underlying neurodegeneration in diabetics. Additionally, investigating the links between DR and other neurodegenerative disorders of the brain including Alzheimer's and Parkinson's disease may reveal shared mechanisms for neurodegeneration and potential therapy options.
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Affiliation(s)
- Moein Ebrahimi
- School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Network of Immunity in Infection, Malignancy, and Autoimmunity, Universal Scientific Education and Research Network (USERN), Tehran, Iran
| | - Paul Thompson
- Imaging Genetics Center, Mark and Mary Stevens Institute for Neuroimaging and Informatics, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Andreas K Lauer
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Sobha Sivaprasad
- National Institute of Health and Care Research Moorfields Biomedical Research Centre, Moorfields Eye Hospital, London, UK
| | - George Perry
- Department of Neuroscience, Developmental and Regenerative Biology, University of Texas and San Antonio, San Antonio, TX, USA
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12
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Provenzano F, Torazza C, Bonifacino T, Bonanno G, Milanese M. The Key Role of Astrocytes in Amyotrophic Lateral Sclerosis and Their Commitment to Glutamate Excitotoxicity. Int J Mol Sci 2023; 24:15430. [PMID: 37895110 PMCID: PMC10607805 DOI: 10.3390/ijms242015430] [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: 08/25/2023] [Revised: 10/12/2023] [Accepted: 10/19/2023] [Indexed: 10/29/2023] Open
Abstract
In the last two decades, there has been increasing evidence supporting non-neuronal cells as active contributors to neurodegenerative disorders. Among glial cells, astrocytes play a pivotal role in driving amyotrophic lateral sclerosis (ALS) progression, leading the scientific community to focus on the "astrocytic signature" in ALS. Here, we summarized the main pathological mechanisms characterizing astrocyte contribution to MN damage and ALS progression, such as neuroinflammation, mitochondrial dysfunction, oxidative stress, energy metabolism impairment, miRNAs and extracellular vesicles contribution, autophagy dysfunction, protein misfolding, and altered neurotrophic factor release. Since glutamate excitotoxicity is one of the most relevant ALS features, we focused on the specific contribution of ALS astrocytes in this aspect, highlighting the known or potential molecular mechanisms by which astrocytes participate in increasing the extracellular glutamate level in ALS and, conversely, undergo the toxic effect of the excessive glutamate. In this scenario, astrocytes can behave as "producers" and "targets" of the high extracellular glutamate levels, going through changes that can affect themselves and, in turn, the neuronal and non-neuronal surrounding cells, thus actively impacting the ALS course. Moreover, this review aims to point out knowledge gaps that deserve further investigation.
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Affiliation(s)
- Francesca Provenzano
- Department of Pharmacy (DIFAR), University of Genoa, 16148 Genova, Italy; (F.P.); (C.T.); (G.B.); (M.M.)
| | - Carola Torazza
- Department of Pharmacy (DIFAR), University of Genoa, 16148 Genova, Italy; (F.P.); (C.T.); (G.B.); (M.M.)
| | - Tiziana Bonifacino
- Department of Pharmacy (DIFAR), University of Genoa, 16148 Genova, Italy; (F.P.); (C.T.); (G.B.); (M.M.)
- Inter-University Center for the Promotion of the 3Rs Principles in Teaching & Research (Centro 3R), 56122 Pisa, Italy
| | - Giambattista Bonanno
- Department of Pharmacy (DIFAR), University of Genoa, 16148 Genova, Italy; (F.P.); (C.T.); (G.B.); (M.M.)
| | - Marco Milanese
- Department of Pharmacy (DIFAR), University of Genoa, 16148 Genova, Italy; (F.P.); (C.T.); (G.B.); (M.M.)
- IRCCS Ospedale Policlinico San Martino, 16132 Genoa, Italy
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13
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León-Fuentes IM, Salgado-Gil MG, Novoa MS, Retamal MA. Connexins in Cancer, the Possible Role of Connexin46 as a Cancer Stem Cell-Determining Protein. Biomolecules 2023; 13:1460. [PMID: 37892142 PMCID: PMC10604234 DOI: 10.3390/biom13101460] [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: 08/17/2023] [Revised: 09/15/2023] [Accepted: 09/22/2023] [Indexed: 10/29/2023] Open
Abstract
Cancer is a widespread and incurable disease caused by genetic mutations, leading to uncontrolled cell proliferation and metastasis. Connexins (Cx) are transmembrane proteins that facilitate intercellular communication via hemichannels and gap junction channels. Among them, Cx46 is found mostly in the eye lens. However, in pathological conditions, Cx46 has been observed in various types of cancers, such as glioblastoma, melanoma, and breast cancer. It has been demonstrated that elevated Cx46 levels in breast cancer contribute to cellular resistance to hypoxia, and it is an enhancer of cancer aggressiveness supporting a pro-tumoral role. Accordingly, Cx46 is associated with an increase in cancer stem cell phenotype. These cells display radio- and chemoresistance, high proliferative abilities, self-renewal, and differentiation capacities. This review aims to consolidate the knowledge of the relationship between Cx46, its role in forming hemichannels and gap junctions, and its connection with cancer and cancer stem cells.
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Affiliation(s)
| | | | | | - Mauricio A. Retamal
- Programa de Comunicación Celular en Cáncer, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, República de Honduras 12740, Las Condes, Santiago 7610496, Chile; (I.M.L.-F.); (M.G.S.-G.); (M.S.N.)
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14
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Cao JW, Liu LY, Yu YC. Gap junctions regulate the development of neural circuits in the neocortex. Curr Opin Neurobiol 2023; 81:102735. [PMID: 37263136 DOI: 10.1016/j.conb.2023.102735] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 04/12/2023] [Accepted: 05/07/2023] [Indexed: 06/03/2023]
Abstract
Gap junctions between cells are ubiquitously expressed in the developing brain. They are involved in major steps of neocortical development, including neurogenesis, cell migration, synaptogenesis, and neural circuit formation, and have been implicated in cortical column formation. Dysfunctional gap junctions can contribute to or even cause a variety of brain diseases. Although the role of gap junctions in neocortical development is better known, a comprehensive understanding of their functions is far from complete. Here we explore several critical open questions surrounding gap junctions and their involvement in neural circuit development. Addressing them will greatly impact our understanding of the fundamental mechanisms of neocortical structure and function as well as the etiology of brain disease.
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Affiliation(s)
- Jun-Wei Cao
- School of Basic Medical Sciences, Xiangnan University, Chenzhou, Hunan 423000, China
| | - Lin-Yun Liu
- Jing'an District Central Hospital of Shanghai, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Shanghai 200032, China
| | - Yong-Chun Yu
- Jing'an District Central Hospital of Shanghai, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science, Institutes of Brain Science, Shanghai 200032, China.
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15
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Rieskamp JD, Rosado-Burgos I, Christofi JE, Ansar E, Einstein D, Walters AE, Valentini V, Bruno JP, Kirby ED. Excitatory amino acid transporter 1 supports adult hippocampal neural stem cell self-renewal. iScience 2023; 26:107068. [PMID: 37534178 PMCID: PMC10391730 DOI: 10.1016/j.isci.2023.107068] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 05/01/2023] [Accepted: 06/05/2023] [Indexed: 08/04/2023] Open
Abstract
Within the adult mammalian dentate gyrus (DG) of the hippocampus, glutamate stimulates neural stem cell (NSC) self-renewing proliferation, providing a link between adult neurogenesis and local circuit activity. Here, we show that glutamate-induced self-renewal of adult DG NSCs requires glutamate transport via excitatory amino acid transporter 1 (EAAT1) to stimulate lipogenesis. Loss of EAAT1 prevented glutamate-induced self-renewing proliferation of NSCs in vitro and in vivo, with little role evident for canonical glutamate receptors. Transcriptomics and further pathway manipulation revealed that glutamate simulation of NSCs relied on EAAT1 transport-stimulated lipogenesis. Our findings demonstrate a critical, direct role for EAAT1 in stimulating NSCs to support neurogenesis in adulthood, thereby providing insights into a non-canonical mechanism by which NSCs sense and respond to their niche.
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Affiliation(s)
- Joshua D. Rieskamp
- Department of Psychology, The Ohio State University, Columbus, OH 43210, USA
| | | | - Jacob E. Christofi
- Department of Psychology, The Ohio State University, Columbus, OH 43210, USA
| | - Eliza Ansar
- Department of Psychology, The Ohio State University, Columbus, OH 43210, USA
| | - Dalia Einstein
- Department of Psychology, The Ohio State University, Columbus, OH 43210, USA
| | - Ashley E. Walters
- Department of Psychology, The Ohio State University, Columbus, OH 43210, USA
| | - Valentina Valentini
- Department of Psychology, The Ohio State University, Columbus, OH 43210, USA
- Department of Biomedical Sciences, University of Cagliari, 09124 Cagliari, Italy
| | - John P. Bruno
- Department of Psychology, The Ohio State University, Columbus, OH 43210, USA
- Department of Neuroscience, The Ohio State University, Columbus, OH 43210, USA
| | - Elizabeth D. Kirby
- Department of Psychology, The Ohio State University, Columbus, OH 43210, USA
- Department of Neuroscience, The Ohio State University, Columbus, OH 43210, USA
- Chronic Brain Injury Program, The Ohio State University, Columbus, OH 43210, USA
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16
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Abrams CK. Mechanisms of Diseases Associated with Mutation in GJC2/Connexin 47. Biomolecules 2023; 13:biom13040712. [PMID: 37189458 DOI: 10.3390/biom13040712] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 04/03/2023] [Accepted: 04/04/2023] [Indexed: 05/17/2023] Open
Abstract
Connexins are members of a family of integral membrane proteins that provide a pathway for both electrical and metabolic coupling between cells. Astroglia express connexin 30 (Cx30)-GJB6 and Cx43-GJA1, while oligodendroglia express Cx29/Cx31.3-GJC3, Cx32-GJB1, and Cx47-GJC2. Connexins organize into hexameric hemichannels (homomeric if all subunits are identical or heteromeric if one or more differs). Hemichannels from one cell then form cell-cell channels with a hemichannel from an apposed cell. (These are termed homotypic if the hemichannels are identical and heterotypic if the hemichannels differ). Oligodendrocytes couple to each other through Cx32/Cx32 or Cx47/Cx47 homotypic channels and they couple to astrocytes via Cx32/Cx30 or Cx47/Cx43 heterotypic channels. Astrocytes couple via Cx30/Cx30 and Cx43/Cx43 homotypic channels. Though Cx32 and Cx47 may be expressed in the same cells, all available data suggest that Cx32 and Cx47 cannot interact heteromerically. Animal models wherein one or in some cases two different CNS glial connexins have been deleted have helped to clarify the role of these molecules in CNS function. Mutations in a number of different CNS glial connexin genes cause human disease. Mutations in GJC2 lead to three distinct phenotypes, Pelizaeus Merzbacher like disease, hereditary spastic paraparesis (SPG44) and subclinical leukodystrophy.
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Affiliation(s)
- Charles K Abrams
- Department of Neurology and Rehabilitation, University of Illinois at Chicago College of Medicine, Chicago, IL 60612, USA
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17
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Yang D, Chen M, Yang S, Deng F, Guo X. Connexin hemichannels and pannexin channels in toxicity: Recent advances and mechanistic insights. Toxicology 2023; 488:153488. [PMID: 36918108 DOI: 10.1016/j.tox.2023.153488] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 03/10/2023] [Accepted: 03/11/2023] [Indexed: 03/14/2023]
Abstract
Connexin hemichannels and pannexin channels are two types of transmembrane channels that allow autocrine/paracrine signalling through the exchange of ions and molecules between the intra- and extracellular compartments. However, owing to the poor selectivity of permeable ions and metabolites, the massive opening of these plasma membrane channels can lead to an excessive influx of toxic substances and an outflux of essential metabolites, such as adenosine triphosphate, glutathione, glutamate and ions, resulting in unbalanced cell homeostasis and impaired cell function. It is becoming increasingly clear that these channels can be activated in response to external stimuli and are involved in toxicity, yet their concrete mechanistic roles in the toxic effects induced by stress and various environmental changes remain poorly defined. This review provides an updated understanding of connexin hemichannels and pannexin channels in response to multiple extrinsic stressors and how these activated channels and their permeable messengers participate in toxicological pathways and processes, including inflammation, oxidative damage, intracellular calcium imbalance, bystander DNA damage and excitotoxicity.
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Affiliation(s)
- Di Yang
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, No. 38 Xueyuan Road, Beijing, China
| | - Mengyuan Chen
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, No. 38 Xueyuan Road, Beijing, China
| | - Sijia Yang
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, No. 38 Xueyuan Road, Beijing, China
| | - Furong Deng
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, No. 38 Xueyuan Road, Beijing, China
| | - Xinbiao Guo
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, No. 38 Xueyuan Road, Beijing, China.
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18
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Quincozes-Santos A, Bobermin LD, Costa NLF, Thomaz NK, Almeida RRDS, Beys-da-Silva WO, Santi L, Rosa RL, Capra D, Coelho-Aguiar JM, DosSantos MF, Heringer M, Cirne-Lima EO, Guimarães JA, Schuler-Faccini L, Gonçalves CA, Moura-Neto V, Souza DO. The role of glial cells in Zika virus-induced neurodegeneration. Glia 2023. [PMID: 36866453 DOI: 10.1002/glia.24353] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
Zika virus (ZIKV) is a strongly neurotropic flavivirus whose infection has been associated with microcephaly in neonates. However, clinical and experimental evidence indicate that ZIKV also affects the adult nervous system. In this regard, in vitro and in vivo studies have shown the ability of ZIKV to infect glial cells. In the central nervous system (CNS), glial cells are represented by astrocytes, microglia, and oligodendrocytes. In contrast, the peripheral nervous system (PNS) constitutes a highly heterogeneous group of cells (Schwann cells, satellite glial cells, and enteric glial cells) spread through the body. These cells are critical in both physiological and pathological conditions; as such, ZIKV-induced glial dysfunctions can be associated with the development and progression of neurological complications, including those related to the adult and aging brain. This review will address the effects of ZIKV infection on CNS and PNS glial cells, focusing on cellular and molecular mechanisms, including changes in the inflammatory response, oxidative stress, mitochondrial dysfunction, Ca2+ and glutamate homeostasis, neural metabolism, and neuron-glia communication. Of note, preventive and therapeutic strategies that focus on glial cells may emerge to delay and/or prevent the development of ZIKV-induced neurodegeneration and its consequences.
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Affiliation(s)
- André Quincozes-Santos
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.,Programa de Pós-Graduação em Neurociências, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.,Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Larissa Daniele Bobermin
- Programa de Pós-Graduação em Neurociências, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Naithan Ludian Fernandes Costa
- Programa de Pós-Graduação em Neurociências, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Natalie K Thomaz
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Rômulo Rodrigo de Souza Almeida
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | | | - Lucélia Santi
- Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil
| | - Rafael L Rosa
- Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil
| | - Daniela Capra
- Instituto Estadual do Cérebro Paulo Niemeyer, Secretaria Estadual de Saúde do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Juliana M Coelho-Aguiar
- Laboratório de Morfogênese Celular, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Marcos Fabio DosSantos
- Laboratório de Propriedades Mecânicas e Biologia Celular, Faculdade de Odontologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Manoela Heringer
- Instituto Estadual do Cérebro Paulo Niemeyer, Secretaria Estadual de Saúde do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | | | | | | | - Carlos-Alberto Gonçalves
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.,Programa de Pós-Graduação em Neurociências, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.,Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Vivaldo Moura-Neto
- Instituto Estadual do Cérebro Paulo Niemeyer, Secretaria Estadual de Saúde do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.,Laboratório de Morfogênese Celular, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Diogo Onofre Souza
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.,Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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19
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Understanding the Role of ATP Release through Connexins Hemichannels during Neurulation. Int J Mol Sci 2023; 24:ijms24032159. [PMID: 36768481 PMCID: PMC9916920 DOI: 10.3390/ijms24032159] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/30/2022] [Accepted: 01/04/2023] [Indexed: 01/25/2023] Open
Abstract
Neurulation is a crucial process in the formation of the central nervous system (CNS), which begins with the folding and fusion of the neural plate, leading to the generation of the neural tube and subsequent development of the brain and spinal cord. Environmental and genetic factors that interfere with the neurulation process promote neural tube defects (NTDs). Connexins (Cxs) are transmembrane proteins that form gap junctions (GJs) and hemichannels (HCs) in vertebrates, allowing cell-cell (GJ) or paracrine (HCs) communication through the release of ATP, glutamate, and NAD+; regulating processes such as cell migration and synaptic transmission. Changes in the state of phosphorylation and/or the intracellular redox potential activate the opening of HCs in different cell types. Cxs such as Cx43 and Cx32 have been associated with proliferation and migration at different stages of CNS development. Here, using molecular and cellular biology techniques (permeability), we demonstrate the expression and functionality of HCs-Cxs, including Cx46 and Cx32, which are associated with the release of ATP during the neurulation process in Xenopus laevis. Furthermore, applications of FGF2 and/or changes in intracellular redox potentials (DTT), well known HCs-Cxs modulators, transiently regulated the ATP release in our model. Importantly, the blockade of HCs-Cxs by carbenoxolone (CBX) and enoxolone (ENX) reduced ATP release with a concomitant formation of NTDs. We propose two possible and highly conserved binding sites (N and E) in Cx46 that may mediate the pharmacological effect of CBX and ENX on the formation of NTDs. In summary, our results highlight the importance of ATP release mediated by HCs-Cxs during neurulation.
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20
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Pun R, Kim MH, North BJ. Role of Connexin 43 phosphorylation on Serine-368 by PKC in cardiac function and disease. Front Cardiovasc Med 2023; 9:1080131. [PMID: 36712244 PMCID: PMC9877470 DOI: 10.3389/fcvm.2022.1080131] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 12/19/2022] [Indexed: 01/13/2023] Open
Abstract
Intercellular communication mediated by gap junction channels and hemichannels composed of Connexin 43 (Cx43) is vital for the propagation of electrical impulses through cardiomyocytes. The carboxyl terminal tail of Cx43 undergoes various post-translational modifications including phosphorylation of its Serine-368 (S368) residue. Protein Kinase C isozymes directly phosphorylate S368 to alter Cx43 function and stability through inducing conformational changes affecting channel permeability or promoting internalization and degradation to reduce intercellular communication between cardiomyocytes. Recent studies have implicated this PKC/Cx43-pS368 circuit in several cardiac-associated diseases. In this review, we describe the molecular and cellular basis of PKC-mediated Cx43 phosphorylation and discuss the implications of Cx43 S368 phosphorylation in the context of various cardiac diseases, such as cardiomyopathy, as well as the therapeutic potential of targeting this pathway.
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Affiliation(s)
- Renju Pun
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, United States
| | - Michael H. Kim
- CHI Health Heart Institute, School of Medicine, Creighton University, Omaha, NE, United States
| | - Brian J. North
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE, United States,*Correspondence: Brian J. North,
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21
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Murray CJ, Vecchiarelli HA, Tremblay MÈ. Enhancing axonal myelination in seniors: A review exploring the potential impact cannabis has on myelination in the aged brain. Front Aging Neurosci 2023; 15:1119552. [PMID: 37032821 PMCID: PMC10073480 DOI: 10.3389/fnagi.2023.1119552] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 02/22/2023] [Indexed: 04/11/2023] Open
Abstract
Consumption of cannabis is on the rise as public opinion trends toward acceptance and its consequent legalization. Specifically, the senior population is one of the demographics increasing their use of cannabis the fastest, but research aimed at understanding cannabis' impact on the aged brain is still scarce. Aging is characterized by many brain changes that slowly alter cognitive ability. One process that is greatly impacted during aging is axonal myelination. The slow degradation and loss of myelin (i.e., demyelination) in the brain with age has been shown to associate with cognitive decline and, furthermore, is a common characteristic of numerous neurological diseases experienced in aging. It is currently not known what causes this age-dependent degradation, but it is likely due to numerous confounding factors (i.e., heightened inflammation, reduced blood flow, cellular senescence) that impact the many cells responsible for maintaining overall homeostasis and myelin integrity. Importantly, animal studies using non-human primates and rodents have also revealed demyelination with age, providing a reliable model for researchers to try and understand the cellular mechanisms at play. In rodents, cannabis was recently shown to modulate the myelination process. Furthermore, studies looking at the direct modulatory impact cannabis has on microglia, astrocytes and oligodendrocyte lineage cells hint at potential mechanisms to prevent some of the more damaging activities performed by these cells that contribute to demyelination in aging. However, research focusing on how cannabis impacts myelination in the aged brain is lacking. Therefore, this review will explore the evidence thus far accumulated to show how cannabis impacts myelination and will extrapolate what this knowledge may mean for the aged brain.
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Affiliation(s)
- Colin J. Murray
- Neuroscience Graduate Program, University of Victoria, Victoria, BC, Canada
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- *Correspondence: Colin J. Murray,
| | | | - Marie-Ève Tremblay
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Départment de Médicine Moléculaire, Université Laval, Québec City, QC, Canada
- Axe Neurosciences, Center de Recherche du CHU de Québec, Université Laval, Québec City, QC, Canada
- Neurology and Neurosurgery Department, McGill University, Montréal, QC, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
- Centre for Advanced Materials and Related Technology (CAMTEC), University of Victoria, Victoria, BC, Canada
- Institute for Aging and Lifelong Health, University of Victoria, Victoria, BC, Canada
- Marie-Ève Tremblay,
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22
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Abstract
Gap junctions, comprising connexin proteins, create conduits directly coupling the cytoplasms of adjacent cells. Expressed in essentially all tissues, dynamic gap junction structures enable the exchange of small molecules including ions and second messengers, and are central to maintenance of homeostasis and synchronized excitability. With such diverse and critical roles throughout the body, it is unsurprising that alterations to gap junction and/or connexin expression and function underlie a broad array of age-related pathologies. From neurological dysfunction to cardiac arrhythmia and bone loss, it is hard to identify a human disease state that does not involve reduced, or in some cases inappropriate, intercellular communication to affect organ function. With a complex life cycle encompassing several key regulatory steps, pathological gap junction remodeling during ageing can arise from alterations in gene expression, translation, intracellular trafficking, and posttranslational modification of connexins. Connexin proteins are now known to "moonlight" and perform a variety of non-junctional functions in the cell, independent of gap junctions. Furthermore, connexin "hemichannels" on the cell surface can communicate with the extracellular space without ever coupling to an adjacent cell to form a gap junction channel. This chapter will focus primarily on gap junctions in ageing, but such non-junctional connexin functions will be referred to where appropriate and the full spectrum of connexin biology should be noted as potentially causative/contributing to some findings in connexin knockout animals, for example.
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Affiliation(s)
- Michael J Zeitz
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, USA.,FBRI Center for Vascular and Heart Research, Roanoke, VA, USA
| | - James W Smyth
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, USA. .,FBRI Center for Vascular and Heart Research, Roanoke, VA, USA. .,Department of Biological Sciences, College of Science, Virginia Tech, Blacksburg, VA, USA. .,Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, VA, USA.
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23
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Connexin 30 Deficiency Ameliorates Disease Progression at the Early Phase in a Mouse Model of Amyotrophic Lateral Sclerosis by Suppressing Glial Inflammation. Int J Mol Sci 2022; 23:ijms232416046. [PMID: 36555685 PMCID: PMC9782489 DOI: 10.3390/ijms232416046] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Connexin 30 (Cx30), which forms gap junctions between astrocytes, regulates cell adhesion and migration, and modulates glutamate transport. Cx30 is upregulated on activated astroglia in central nervous system inflammatory lesions, including spinal cord lesions in mutant superoxide dismutase 1 (mSOD1) transgenic amyotrophic lateral sclerosis (ALS) model mice. Here, we investigated the role of Cx30 in mSOD1 mice. Cx30 was highly expressed in the pre-onset stage in mSOD1 mice. mSOD1 mice with knockout (KO) of the Cx30 gene (Cx30KO-mSOD1 mice) showed delayed disease onset and tended to have an extended survival period (log-rank, p = 0.09). At the progressive and end stages of the disease, anterior horn cells were significantly preserved in Cx30KO-mSOD1 mice. In lesions of these mice, glial fibrillary acidic protein/C3-positive inflammatory astroglia were decreased. Additionally, the activation of astrocytes in Cx30KO-mSOD1 mice was reduced compared with mSOD1 mice by gene expression microarray. Furthermore, expression of connexin 43 at the pre-onset stage was downregulated in Cx30KO-mSOD1 mice. These findings suggest that reduced expression of astroglial Cx30 at the early disease stage in ALS model mice protects neurons by attenuating astroglial inflammation.
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Kilb W, Kirischuk S. GABA Release from Astrocytes in Health and Disease. Int J Mol Sci 2022; 23:ijms232415859. [PMID: 36555501 PMCID: PMC9784789 DOI: 10.3390/ijms232415859] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/06/2022] [Accepted: 12/10/2022] [Indexed: 12/15/2022] Open
Abstract
Astrocytes are the most abundant glial cells in the central nervous system (CNS) mediating a variety of homeostatic functions, such as spatial K+ buffering or neurotransmitter reuptake. In addition, astrocytes are capable of releasing several biologically active substances, including glutamate and GABA. Astrocyte-mediated GABA release has been a matter of debate because the expression level of the main GABA synthesizing enzyme glutamate decarboxylase is quite low in astrocytes, suggesting that low intracellular GABA concentration ([GABA]i) might be insufficient to support a non-vesicular GABA release. However, recent studies demonstrated that, at least in some regions of the CNS, [GABA]i in astrocytes might reach several millimoles both under physiological and especially pathophysiological conditions, thereby enabling GABA release from astrocytes via GABA-permeable anion channels and/or via GABA transporters operating in reverse mode. In this review, we summarize experimental data supporting both forms of GABA release from astrocytes in health and disease, paying special attention to possible feedback mechanisms that might govern the fine-tuning of astrocytic GABA release and, in turn, the tonic GABAA receptor-mediated inhibition in the CNS.
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Benedikt J, Malpica-Nieves CJ, Rivera Y, Méndez-González M, Nichols CG, Veh RW, Eaton MJ, Skatchkov SN. The Polyamine Spermine Potentiates the Propagation of Negatively Charged Molecules through the Astrocytic Syncytium. Biomolecules 2022; 12:biom12121812. [PMID: 36551240 PMCID: PMC9775384 DOI: 10.3390/biom12121812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/16/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022] Open
Abstract
The interest in astrocytes, the silent brain cells that accumulate polyamines (PAs), is growing. PAs exert anti-inflammatory, antioxidant, antidepressant, neuroprotective, and other beneficial effects, including increasing longevity in vivo. Unlike neurons, astrocytes are extensively coupled to others via connexin (Cx) gap junctions (GJs). Although there are striking modulatory effects of PAs on neuronal receptors and channels, PA regulation of the astrocytic GJs is not well understood. We studied GJ-propagation using molecules of different (i) electrical charge, (ii) structure, and (iii) molecular weight. Loading single astrocytes with patch pipettes containing membrane-impermeable dyes, we observed that (i) even small molecules do not easily permeate astrocytic GJs, (ii) the ratio of the charge to weight of these molecules is the key determinant of GJ permeation, (iii) the PA spermine (SPM) induced the propagation of negatively charged molecules via GJs, (iv) while no effects were observed on propagation of macromolecules with net-zero charge. The GJ uncoupler carbenoxolone (CBX) blocked such propagation. Taken together, these findings indicate that SPM is essential for astrocytic GJ communication and selectively facilitates intracellular propagation via GJs for negatively charged molecules through glial syncytium.
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Affiliation(s)
- Jan Benedikt
- Department of Physiology, Universidad Central del Caribe, Bayamón, PR 00956, USA
| | - Christian J. Malpica-Nieves
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR 00956, USA
- Correspondence: (C.J.M.-N.); (S.N.S.); Tel.: +1-787-798-3001 (ext. 2057) (S.N.S.)
| | - Yomarie Rivera
- Department of Chiropractic, Universidad Central del Caribe, Bayamón, PR 00956, USA
| | | | - Colin G. Nichols
- Department of Cell Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Rüdiger W. Veh
- Institut für Zell- und Neurobiologie, Charité, 10115 Berlin, Germany
| | - Misty J. Eaton
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR 00956, USA
| | - Serguei N. Skatchkov
- Department of Physiology, Universidad Central del Caribe, Bayamón, PR 00956, USA
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR 00956, USA
- Correspondence: (C.J.M.-N.); (S.N.S.); Tel.: +1-787-798-3001 (ext. 2057) (S.N.S.)
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Nishimura Y, Masaki K, Matsuse D, Yamaguchi H, Tanaka T, Matsuo E, Hayashida S, Watanabe M, Matsushita T, Sadashima S, Sasagasako N, Yamasaki R, Isobe N, Iwaki T, Kira J. Early and extensive alterations of glial connexins, distal oligodendrogliopathy type demyelination, and nodal/paranodal pathology are characteristic of multiple system atrophy. Brain Pathol 2022; 33:e13131. [PMID: 36368713 PMCID: PMC10154368 DOI: 10.1111/bpa.13131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 10/24/2022] [Indexed: 11/13/2022] Open
Abstract
The pathological hallmark of multiple system atrophy (MSA) is aberrant accumulation of phosphorylated α-synuclein in oligodendrocytes, forming glial cytoplasmic inclusions (GCIs). Extensive demyelination occurs particularly in the olivopontocerebellar and striatonigral pathways, but its precise mechanism remains elusive. Glial connexins (Cxs), which form gap junction channels between astrocytes and oligodendrocytes, play critical roles in myelin maintenance, and have not been studied in MSA. Therefore, we immunohistochemically investigated glial Cx changes in the cerebellar afferent fibers in 15 autopsied patients with MSA. We classified demyelinating lesions into three stages based on Klüver-Barrera staining: early (Stage I), intermediate (Stage II), and late (Stage III) stages showing subtle, moderate, and severe myelin reduction, respectively. Myelin-associated glycoprotein, but not myelin oligodendrocyte glycoprotein, was preferentially decreased in Stage I, suggesting distal oligodendrogliopathy type demyelination. Accumulation of phosphorylated α-synuclein in oligodendrocytes was frequently seen in Stage I but less frequently observed in Stages II and III. Tubulin polymerization-promoting protein (TPPP/p25α)-positive oligodendrocytes were preserved in Stage I but successively decreased in Stages II and III. Even at Stage I, Cx32 was nearly absent from myelin, despite the relative preservation of other nodal proteins, such as neurofascin, claudin-11/oligodendrocyte-specific protein, and contactin-associated protein 1, which successively decreased in the later stages. Cx32 was re-distributed in the oligodendrocyte cytoplasm and co-localized with GCIs. Cx47 gradually decreased at the oligodendrocyte surface in a stage-dependent manner but was not co-localized with GCIs. Astrocytic Cx43 was down-regulated in Stage I but up-regulated in Stages II and III, reflecting astrogliosis. Cx43/Cx47 gap junctions significantly decreased from Stage I to III. Activated microglia/macrophages and T cells infiltrated in Stage I rather than Stages II and III. Therefore, early and extensive alterations of glial Cxs, particularly Cx32 loss, occur in MSA and may accelerate distal oligodendrogliopathy type demyelination and nodal/paranodal dysfunction through disruption of inter-glial communication.
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Affiliation(s)
- Yuji Nishimura
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
| | - Katsuhisa Masaki
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
| | - Dai Matsuse
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
| | - Hiroo Yamaguchi
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
| | - Tatsunori Tanaka
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
- Sumitomo Pharma Osaka Japan
| | - Eriko Matsuo
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
| | - Shotaro Hayashida
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
| | - Mitsuru Watanabe
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
| | - Takuya Matsushita
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
| | - Shoko Sadashima
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
- Department of Neuropathology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
| | - Naokazu Sasagasako
- Department of Neurology, Neuro‐Muscular Center National Omuta Hospital Fukuoka Japan
| | - Ryo Yamasaki
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
| | - Noriko Isobe
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
| | - Toru Iwaki
- Department of Neuropathology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
| | - Jun‐ichi Kira
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences Kyushu University Fukuoka Japan
- Translational Neuroscience Center, Graduate School of Medicine, and School of Pharmacy at Fukuoka International University of Health and Welfare Ookawa Japan
- Department of Neurology, Brain and Nerve Center Fukuoka Central Hospital Fukuoka Japan
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Zhang NN, Zhang Y, Wang ZZ, Chen NH. Connexin 43: insights into candidate pathological mechanisms of depression and its implications in antidepressant therapy. Acta Pharmacol Sin 2022; 43:2448-2461. [PMID: 35145238 PMCID: PMC9525669 DOI: 10.1038/s41401-022-00861-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 01/06/2022] [Indexed: 11/09/2022] Open
Abstract
Major depressive disorder (MDD), a chronic and recurrent disease characterized by anhedonia, pessimism or even suicidal thought, remains a major chronic mental concern worldwide. Connexin 43 (Cx43) is the most abundant connexin expressed in astrocytes and forms the gap junction channels (GJCs) between astrocytes, the most abundant and functional glial cells in the brain. Astrocytes regulate neurons' synaptic strength and function by expressing receptors and regulating various neurotransmitters. Astrocyte dysfunction causes synaptic abnormalities, which are related to various mood disorders, e.g., depression. Increasing evidence suggests a crucial role of Cx43 in the pathogenesis of depression. Depression down-regulates Cx43 expression in humans and rats, and dysfunction of Cx43 also induces depressive behaviors in rats and mice. Recently Cx43 has received considerable critical attention and is highly implicated in the onset of depression. However, the pathological mechanisms of depression-like behavior associated with Cx43 still remain ambiguous. In this review we summarize the recent progress regarding the underlying mechanisms of Cx43 in the etiology of depression-like behaviors including gliotransmission, metabolic disorders, and neuroinflammation. We also discuss the effects of antidepressants (monoamine antidepressants and ketamine) on Cx43. The clarity of the candidate pathological mechanisms of depression-like behaviors associated with Cx43 and its potential pharmacological roles for antidepressants will benefit the exploration of a novel antidepressant target.
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Affiliation(s)
- Ning-Ning Zhang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Yi Zhang
- Department of Anatomy, School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, 102488, China
| | - Zhen-Zhen Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China.
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China.
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Liu W, Rask-Andersen H. GJB2 and GJB6 gene transcripts in the human cochlea: A study using RNAscope, confocal, and super-resolution structured illumination microscopy. Front Mol Neurosci 2022; 15:973646. [PMID: 36204137 PMCID: PMC9530750 DOI: 10.3389/fnmol.2022.973646] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 08/01/2022] [Indexed: 11/26/2022] Open
Abstract
Background Gap junction (GJ) proteins, connexin26 and 30, are highly prevalent in the human cochlea (HC), where they are involved in transcellular signaling, metabolic supply, and fluid homeostasis. Their genes, GJB2 and GJB6, are both located at the DFNB1 locus on chromosome 13q12. Mutations in GJB2 may cause mild to profound non-syndromic deafness. Here, we analyzed for the first time the various expressions of GJB2 and GJB6 gene transcripts in the different cell networks in the HC using the RNAscope technique. Materials and methods Archival paraformaldehyde-fixed sections of surgically obtained HC were used to label single mRNA oligonucleotides using the sensitive multiplex RNAscope® technique with fluorescent-tagged probes. Positive and negative controls also included the localization of ATP1A1, ATP1A2, and KCNJ10 gene transcripts in order to validate the specificity of labeling. Results Confocal and super-resolution structured illumination microscopy (SR-SIM) detected single gene transcripts as brightly stained puncta. The GJB2 and GJB6 gene transcripts were distributed in the epithelial and connective tissue systems in all three cochlear turns. The largest number of GJB2 and GJB6 gene transcripts was in the outer sulcus, spiral ligament, and stria vascularis (SV). Oligonucleotides were present in the supporting cells of the organ of Corti (OC), spiral limbus fibrocytes, and the floor of the scala vestibuli. Multiplex gene data suggest that cells in the cochlear lateral wall contain either GJB2 or GJB6 gene transcripts or both. The GJB6, but not GJB2, gene transcripts were found in the intermediate cells but none were found in the marginal cells. There were no GJB2 or GJB6 gene transcripts found in the hair cells and only a few in the spiral ganglion cells. Conclusion Both GJB2 and GJB6 mRNA gene transcripts were localized in cells in the adult HC using RNAscope®in situ hybridization (ISH) and high resolution microscopy. Generally, GJB6 dominated over GJB2, except in the basal cells. Results suggest that cells may contain either GJB2 or GJB6 gene transcripts or both. This may be consistent with specialized GJ plaques having separate channel permeability and gating properties. A reduction in the number of GJB2 gene transcripts was found in the basal turn. Such information may be useful for future gene therapy.
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Zlomuzica A, Plank L, Dere E. A new path to mental disorders: Through gap junction channels and hemichannels. Neurosci Biobehav Rev 2022; 142:104877. [PMID: 36116574 DOI: 10.1016/j.neubiorev.2022.104877] [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: 01/31/2022] [Revised: 08/20/2022] [Accepted: 09/13/2022] [Indexed: 11/18/2022]
Abstract
Behavioral disturbances related to emotional regulation, reward processing, cognition, sleep-wake regulation and activity/movement represent core symptoms of most common mental disorders. Increasing empirical and theoretical evidence suggests that normal functioning of these behavioral domains relies on fine graded coordination of neural and glial networks which are maintained and modulated by intercellular gap junction channels and unapposed pannexin or connexin hemichannels. Dysfunctions in these networks might contribute to the development and maintenance of psychopathological and neurobiological features associated with mental disorders. Here we review and discuss the evidence indicating a prominent role of gap junction channel and hemichannel dysfunction in core symptoms of mental disorders. We further discuss how the increasing knowledge on intercellular gap junction channels and unapposed pannexin or connexin hemichannels in the brain might lead to deeper mechanistic insight in common mental disorders and to the development of novel treatment approaches. We further attempt to exemplify what type of future research on this topic could be integrated into multidimensional approaches to understand and cure mental disorders.
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Affiliation(s)
- Armin Zlomuzica
- Department of Behavioral and Clinical Neuroscience, Ruhr-University Bochum (RUB), Massenbergstraße 9-13, D-44787 Bochum, Germany.
| | - Laurin Plank
- Department of Behavioral and Clinical Neuroscience, Ruhr-University Bochum (RUB), Massenbergstraße 9-13, D-44787 Bochum, Germany
| | - Ekrem Dere
- Department of Behavioral and Clinical Neuroscience, Ruhr-University Bochum (RUB), Massenbergstraße 9-13, D-44787 Bochum, Germany; Sorbonne Université. Institut de Biologie Paris-Seine, (IBPS), Département UMR 8256: Adaptation Biologique et Vieillissement, UFR des Sciences de la Vie, Campus Pierre et Marie Curie, Bâtiment B, 9 quai Saint Bernard, F-75005 Paris, France.
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30
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Fernández-Olivares A, Durán-Jara E, Verdugo DA, Fiori MC, Altenberg GA, Stehberg J, Alfaro I, Calderón JF, Retamal MA. Extracellular Cysteines Are Critical to Form Functional Cx46 Hemichannels. Int J Mol Sci 2022; 23:7252. [PMID: 35806258 PMCID: PMC9266770 DOI: 10.3390/ijms23137252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/16/2022] [Accepted: 06/18/2022] [Indexed: 12/10/2022] Open
Abstract
Connexin (Cxs) hemichannels participate in several physiological and pathological processes, but the molecular mechanisms that control their gating remain elusive. We aimed at determining the role of extracellular cysteines (Cys) in the gating and function of Cx46 hemichannels. We studied Cx46 and mutated all of its extracellular Cys to alanine (Ala) (one at a time) and studied the effects of the Cys mutations on Cx46 expression, localization, and hemichannel activity. Wild-type Cx46 and Cys mutants were expressed at comparable levels, with similar cellular localization. However, functional experiments showed that hemichannels formed by the Cys mutants did not open either in response to membrane depolarization or removal of extracellular divalent cations. Molecular-dynamics simulations showed that Cys mutants may show a possible alteration in the electrostatic potential of the hemichannel pore and an altered disposition of important residues that could contribute to the selectivity and voltage dependency in the hemichannels. Replacement of extracellular Cys resulted in "permanently closed hemichannels", which is congruent with the inhibition of the Cx46 hemichannel by lipid peroxides, through the oxidation of extracellular Cys. These results point to the modification of extracellular Cys as potential targets for the treatment of Cx46-hemichannel associated pathologies, such as cataracts and cancer, and may shed light into the gating mechanisms of other Cx hemichannels.
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Affiliation(s)
- Ainoa Fernández-Olivares
- Programa de Comunicación Celular en Cáncer, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago 7780272, Chile; (A.F.-O.); (I.A.)
| | - Eduardo Durán-Jara
- Centro de Medicina Regenerativa, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago 7780272, Chile;
| | - Daniel A. Verdugo
- Laboratorio de Neurobiología, Instituto de Ciencias Biomédicas, Facultad de Medicina y Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago 7780272, Chile; (D.A.V.); (J.S.)
| | - Mariana C. Fiori
- Department of Cell Physiology and Molecular Biophysics and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6551, USA; (M.C.F.); (G.A.A.)
| | - Guillermo A. Altenberg
- Department of Cell Physiology and Molecular Biophysics and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6551, USA; (M.C.F.); (G.A.A.)
| | - Jimmy Stehberg
- Laboratorio de Neurobiología, Instituto de Ciencias Biomédicas, Facultad de Medicina y Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago 7780272, Chile; (D.A.V.); (J.S.)
| | - Iván Alfaro
- Programa de Comunicación Celular en Cáncer, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago 7780272, Chile; (A.F.-O.); (I.A.)
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Santiago 7690000, Chile
| | - Juan Francisco Calderón
- Centro de Genética y Genómica, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago 7780272, Chile
| | - Mauricio A. Retamal
- Programa de Comunicación Celular en Cáncer, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago 7780272, Chile; (A.F.-O.); (I.A.)
- Centro Científico y Tecnológico de Excelencia Ciencia & Vida, Santiago 7690000, Chile
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago 7690000, Chile
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McDouall A, Zhou KQ, Bennet L, Green CR, Gunn AJ, Davidson JO. Connexins, Pannexins and Gap Junctions in Perinatal Brain Injury. Biomedicines 2022; 10:biomedicines10061445. [PMID: 35740466 PMCID: PMC9220888 DOI: 10.3390/biomedicines10061445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/15/2022] [Accepted: 06/15/2022] [Indexed: 11/18/2022] Open
Abstract
Perinatal brain injury secondary to hypoxia-ischemia and/or infection/inflammation remains a major cause of disability. Therapeutic hypothermia significantly improves outcomes, but in randomized controlled trials nearly half of infants still died or survived with disability, showing that additional interventions are needed. There is growing evidence that brain injury spreads over time from injured to previously uninjured regions of the brain. At least in part, this spread is related to opening of connexin hemichannels and pannexin channels, both of which are large conductance membrane channels found in many brain cells. Opening of these membrane channels releases adenosine triphosphate (ATP), and other neuroactive molecules, into the extracellular space. ATP has an important role in normal signaling, but pathologically can trigger the assembly of the multi-protein inflammasome complex. The inflammasome complex promotes activation of inflammatory caspases, and release of inflammatory cytokines. Overall, the connexin hemichannel appears to play a primary role in propagation of injury and chronic disease, and connexin hemichannel blockade has been shown to be neuroprotective in multiple animal models. Thus, there is potential for some blockers of connexin or pannexin channels to be developed into targeted interventions that could be used in conjunction with or separate to therapeutic hypothermia.
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Affiliation(s)
- Alice McDouall
- U1 Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1023, New Zealand; (A.M.); (K.Q.Z.); (L.B.); (A.J.G.)
| | - Kelly Q. Zhou
- U1 Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1023, New Zealand; (A.M.); (K.Q.Z.); (L.B.); (A.J.G.)
| | - Laura Bennet
- U1 Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1023, New Zealand; (A.M.); (K.Q.Z.); (L.B.); (A.J.G.)
| | - Colin R. Green
- Department of Ophthalmology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1023, New Zealand;
| | - Alistair J. Gunn
- U1 Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1023, New Zealand; (A.M.); (K.Q.Z.); (L.B.); (A.J.G.)
| | - Joanne O. Davidson
- U1 Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1023, New Zealand; (A.M.); (K.Q.Z.); (L.B.); (A.J.G.)
- Correspondence:
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Jang MW, Lim J, Park MG, Lee JH, Lee CJ. Active role of glia-like supporting cells in the organ of Corti: Membrane proteins and their roles in hearing. Glia 2022; 70:1799-1825. [PMID: 35713516 DOI: 10.1002/glia.24229] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 05/23/2022] [Accepted: 05/30/2022] [Indexed: 12/13/2022]
Abstract
The organ of Corti, located in the cochlea in the inner ear, is one of the major sensory organs involved in hearing. The organ of Corti consists of hair cells, glia-like supporting cells, and the cochlear nerve, which work in harmony to receive sound from the outer ear and transmit auditory signals to the cochlear nucleus in the auditory ascending pathway. In this process, maintenance of the endocochlear potential, with a high potassium gradient and clearance of electrolytes and biochemicals in the inner ear, is critical for normal sound transduction. There is an emerging need for a thorough understanding of each cell type involved in this process to understand the sophisticated mechanisms of the organ of Corti. Hair cells have long been thought to be active, playing a primary role in the cochlea in actively detecting and transmitting signals. In contrast, supporting cells are thought to be silent and function to support hair cells. However, growing lines of evidence regarding the membrane proteins that mediate ionic movement in supporting cells have demonstrated that supporting cells are not silent, but actively play important roles in normal signal transduction. In this review, we summarize studies that characterize diverse membrane proteins according to the supporting cell subtypes involved in cochlear physiology and hearing. This review contributes to a better understanding of supporting cell functions and facilitates the development of potential therapeutic tools for hearing loss.
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Affiliation(s)
- Minwoo Wendy Jang
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Jiwoon Lim
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea.,IBS School, University of Science and Technology (UST), Daejeon, Republic of Korea
| | - Mingu Gordon Park
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Jae-Hun Lee
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - C Justin Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea.,IBS School, University of Science and Technology (UST), Daejeon, Republic of Korea
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Satarker S, Bojja SL, Gurram PC, Mudgal J, Arora D, Nampoothiri M. Astrocytic Glutamatergic Transmission and Its Implications in Neurodegenerative Disorders. Cells 2022; 11:cells11071139. [PMID: 35406702 PMCID: PMC8997779 DOI: 10.3390/cells11071139] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/12/2022] [Accepted: 03/13/2022] [Indexed: 12/11/2022] Open
Abstract
Several neurodegenerative disorders involve impaired neurotransmission, and glutamatergic neurotransmission sets a prototypical example. Glutamate is a predominant excitatory neurotransmitter where the astrocytes play a pivotal role in maintaining the extracellular levels through release and uptake mechanisms. Astrocytes modulate calcium-mediated excitability and release several neurotransmitters and neuromodulators, including glutamate, and significantly modulate neurotransmission. Accumulating evidence supports the concept of excitotoxicity caused by astrocytic glutamatergic release in pathological conditions. Thus, the current review highlights different vesicular and non-vesicular mechanisms of astrocytic glutamate release and their implication in neurodegenerative diseases. As in presynaptic neurons, the vesicular release of astrocytic glutamate is also primarily meditated by calcium-mediated exocytosis. V-ATPase is crucial in the acidification and maintenance of the gradient that facilitates the vesicular storage of glutamate. Along with these, several other components, such as cystine/glutamate antiporter, hemichannels, BEST-1, TREK-1, purinergic receptors and so forth, also contribute to glutamate release under physiological and pathological conditions. Events of hampered glutamate uptake could promote inflamed astrocytes to trigger repetitive release of glutamate. This could be favorable towards the development and worsening of neurodegenerative diseases. Therefore, across neurodegenerative diseases, we review the relations between defective glutamatergic signaling and astrocytic vesicular and non-vesicular events in glutamate homeostasis. The optimum regulation of astrocytic glutamatergic transmission could pave the way for the management of these diseases and add to their therapeutic value.
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Affiliation(s)
- Sairaj Satarker
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Sree Lalitha Bojja
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Prasada Chowdari Gurram
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Jayesh Mudgal
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
| | - Devinder Arora
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
- School of Pharmacy and Medical Sciences, Griffith University, Gold Coast, QLD 4222, Australia;
| | - Madhavan Nampoothiri
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal 576104, India; (S.S.); (S.L.B.); (P.C.G.); (J.M.)
- Correspondence:
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Rieck J, Skatchkov SN, Derst C, Eaton MJ, Veh RW. Unique Chemistry, Intake, and Metabolism of Polyamines in the Central Nervous System (CNS) and Its Body. Biomolecules 2022; 12:biom12040501. [PMID: 35454090 PMCID: PMC9025450 DOI: 10.3390/biom12040501] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 02/04/2023] Open
Abstract
Polyamines (PAs) are small, versatile molecules with two or more nitrogen-containing positively charged groups and provide widespread biological functions. Most of these aspects are well known and covered by quite a number of excellent surveys. Here, the present review includes novel aspects and questions: (1) It summarizes the role of most natural and some important synthetic PAs. (2) It depicts PA uptake from nutrition and bacterial production in the intestinal system following loss of PAs via defecation. (3) It highlights the discrepancy between the high concentrations of PAs in the gut lumen and their low concentration in the blood plasma and cerebrospinal fluid, while concentrations in cellular cytoplasm are much higher. (4) The present review provides a novel and complete scheme for the biosynthesis of Pas, including glycine, glutamate, proline and others as PA precursors, and provides a hypothesis that the agmatine pathway may rescue putrescine production when ODC knockout seems to be lethal (solving the apparent contradiction in the literature). (5) It summarizes novel data on PA transport in brain glial cells explaining why these cells but not neurons preferentially accumulate PAs. (6) Finally, it provides a novel and complete scheme for PA interconversion, including hypusine, putreanine, and GABA (unique gliotransmitter) as end-products. Altogether, this review can serve as an updated contribution to understanding the PA mystery.
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Affiliation(s)
- Julian Rieck
- Institut für Zell- und Neurobiologie, Centrum 2, Charité—Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany;
| | - Serguei N. Skatchkov
- Department of Physiology, Universidad Central del Caribe, Bayamón, PR 00956, USA
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR 00956, USA;
- Correspondence: (S.N.S.); (R.W.V.)
| | - Christian Derst
- Institut für Integrative Neuroanatomie, Centrum 2, Charité—Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany;
| | - Misty J. Eaton
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR 00956, USA;
| | - Rüdiger W. Veh
- Institut für Zell- und Neurobiologie, Centrum 2, Charité—Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany;
- Correspondence: (S.N.S.); (R.W.V.)
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Linsambarth S, Carvajal FJ, Moraga‐Amaro R, Mendez L, Tamburini G, Jimenez I, Verdugo DA, Gómez GI, Jury N, Martínez P, Zundert B, Varela‐Nallar L, Retamal MA, Martin C, Altenberg GA, Fiori MC, Cerpa W, Orellana JA, Stehberg J. Astroglial gliotransmitters released via Cx43 hemichannels regulate NMDAR‐dependent transmission and short‐term fear memory in the basolateral amygdala. FASEB J 2022; 36:e22134. [DOI: 10.1096/fj.202100798rr] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 11/11/2022]
Affiliation(s)
- Sergio Linsambarth
- Laboratorio de Neurobiología Instituto de Ciencias Biomédicas Facultad de Medicina y Facultad de Ciencias de la Vida Universidad Andres Bello Santiago Chile
| | - Francisco J. Carvajal
- Laboratorio de Función y Patología Neuronal Departamento de Biología Celular y Molecular Facultad de Ciencias Biológicas Pontificia Universidad Católica de Chile Santiago Chile
| | - Rodrigo Moraga‐Amaro
- Laboratorio de Neurobiología Instituto de Ciencias Biomédicas Facultad de Medicina y Facultad de Ciencias de la Vida Universidad Andres Bello Santiago Chile
| | - Luis Mendez
- Laboratorio de Neurobiología Instituto de Ciencias Biomédicas Facultad de Medicina y Facultad de Ciencias de la Vida Universidad Andres Bello Santiago Chile
| | - Giovanni Tamburini
- Laboratorio de Neurobiología Instituto de Ciencias Biomédicas Facultad de Medicina y Facultad de Ciencias de la Vida Universidad Andres Bello Santiago Chile
| | - Ivanka Jimenez
- Laboratorio de Neurobiología Instituto de Ciencias Biomédicas Facultad de Medicina y Facultad de Ciencias de la Vida Universidad Andres Bello Santiago Chile
| | - Daniel Antonio Verdugo
- Laboratorio de Neurobiología Instituto de Ciencias Biomédicas Facultad de Medicina y Facultad de Ciencias de la Vida Universidad Andres Bello Santiago Chile
| | - Gonzalo I. Gómez
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud Universidad Autónoma de Chile Santiago Chile
| | - Nur Jury
- Instituto de Ciencias Biomédicas Facultad de Medicina y Facultad de Ciencias de la Vida Universidad Andres Bello Santiago Chile
| | - Pablo Martínez
- Instituto de Ciencias Biomédicas Facultad de Medicina y Facultad de Ciencias de la Vida Universidad Andres Bello Santiago Chile
| | - Brigitte Zundert
- Instituto de Ciencias Biomédicas Facultad de Medicina y Facultad de Ciencias de la Vida Universidad Andres Bello Santiago Chile
| | - Lorena Varela‐Nallar
- Instituto de Ciencias Biomédicas Facultad de Medicina y Facultad de Ciencias de la Vida Universidad Andres Bello Santiago Chile
| | - Mauricio A. Retamal
- Centro de Fisiología Celular e Integrativa. Facultad de Medicina Clínica Alemana Universidad del Desarrollo Santiago Chile
| | - Claire Martin
- Unité de Biologie Fonctionnelle et Adaptative Centre National la Recherche Scientifique Unité Mixte de Recherche 8251 Université Paris Diderot, Sorbonne Paris Cité Paris France
| | - Guillermo A. Altenberg
- Department of Cell Physiology and Molecular Biophysics Center for Membrane Protein Research Texas Tech University Health Sciences Center Lubbock Texas USA
| | - Mariana C. Fiori
- Department of Cell Physiology and Molecular Biophysics Center for Membrane Protein Research Texas Tech University Health Sciences Center Lubbock Texas USA
| | - Waldo Cerpa
- Laboratorio de Función y Patología Neuronal Departamento de Biología Celular y Molecular Facultad de Ciencias Biológicas Pontificia Universidad Católica de Chile Santiago Chile
| | - Juan A. Orellana
- Departamento de Neurología Escuela de Medicina Pontificia Universidad Católica de Chile Santiago Chile
| | - Jimmy Stehberg
- Laboratorio de Neurobiología Instituto de Ciencias Biomédicas Facultad de Medicina y Facultad de Ciencias de la Vida Universidad Andres Bello Santiago Chile
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Mulkey DK, Olsen ML, Ou M, Cleary CM, Du G. Putative Roles of Astrocytes in General Anesthesia. Curr Neuropharmacol 2022; 20:5-15. [PMID: 33588730 PMCID: PMC9199541 DOI: 10.2174/1570159x19666210215120755] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 01/29/2021] [Accepted: 02/06/2021] [Indexed: 02/08/2023] Open
Abstract
General anesthetics are a mainstay of modern medicine, and although much progress has been made towards identifying molecular targets of anesthetics and neural networks contributing to endpoints of general anesthesia, our understanding of how anesthetics work remains unclear. Reducing this knowledge gap is of fundamental importance to prevent unwanted and life-threatening side-effects associated with general anesthesia. General anesthetics are chemically diverse, yet they all have similar behavioral endpoints, and so for decades, research has sought to identify a single underlying mechanism to explain how anesthetics work. However, this effort has given way to the 'multiple target hypothesis' as it has become clear that anesthetics target many cellular proteins, including GABAA receptors, glutamate receptors, voltage-independent K+ channels, and voltagedependent K+, Ca2+ and Na+ channels, to name a few. Yet, despite evidence that astrocytes are capable of modulating multiple aspects of neural function and express many anesthetic target proteins, they have been largely ignored as potential targets of anesthesia. The purpose of this brief review is to highlight the effects of anesthetic on astrocyte processes and identify potential roles of astrocytes in behavioral endpoints of anesthesia (hypnosis, amnesia, analgesia, and immobilization).
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Affiliation(s)
- Daniel K. Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, StorrsCT, USA;,Address correspondence to this author at the Department of Physiology and Neurobiology, University of Connecticut, Storrs CT, USA; E-mail:
| | | | | | - Colin M. Cleary
- Department of Physiology and Neurobiology, University of Connecticut, StorrsCT, USA
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García-Gaytán AC, Hernández-Abrego A, Díaz-Muñoz M, Méndez I. Glutamatergic system components as potential biomarkers and therapeutic targets in cancer in non-neural organs. Front Endocrinol (Lausanne) 2022; 13:1029210. [PMID: 36457557 PMCID: PMC9705578 DOI: 10.3389/fendo.2022.1029210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 10/24/2022] [Indexed: 11/17/2022] Open
Abstract
Glutamate is one of the most abundant amino acids in the blood. Besides its role as a neurotransmitter in the brain, it is a key substrate in several metabolic pathways and a primary messenger that acts through its receptors outside the central nervous system (CNS). The two main types of glutamate receptors, ionotropic and metabotropic, are well characterized in CNS and have been recently analyzed for their roles in non-neural organs. Glutamate receptor expression may be particularly important for tumor growth in organs with high concentrations of glutamate and might also influence the propensity of such tumors to set metastases in glutamate-rich organs, such as the liver. The study of glutamate transporters has also acquired relevance in the physiology and pathologies outside the CNS, especially in the field of cancer research. In this review, we address the recent findings about the expression of glutamatergic system components, such as receptors and transporters, their role in the physiology and pathology of cancer in non-neural organs, and their possible use as biomarkers and therapeutic targets.
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Abstract
Drug addiction remains a key biomedical challenge facing current neuroscience research. In addition to neural mechanisms, the focus of the vast majority of studies to date, astrocytes have been increasingly recognized as an "accomplice." According to the tripartite synapse model, astrocytes critically regulate nearby pre- and postsynaptic neuronal substrates to craft experience-dependent synaptic plasticity, including synapse formation and elimination. Astrocytes within brain regions that are implicated in drug addiction exhibit dynamic changes in activity upon exposure to cocaine and subsequently undergo adaptive changes themselves during chronic drug exposure. Recent results have identified several key astrocytic signaling pathways that are involved in cocaine-induced synaptic and circuit adaptations. In this review, we provide a brief overview of the role of astrocytes in regulating synaptic transmission and neuronal function, and discuss how cocaine influences these astrocyte-mediated mechanisms to induce persistent synaptic and circuit alterations that promote cocaine seeking and relapse. We also consider the therapeutic potential of targeting astrocytic substrates to ameliorate drug-induced neuroplasticity for behavioral benefits. While primarily focusing on cocaine-induced astrocytic responses, we also include brief discussion of other drugs of abuse where data are available.
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Ransom BR, Goldberg MP, Arai K, Baltan S. White Matter Pathophysiology. Stroke 2022. [DOI: 10.1016/b978-0-323-69424-7.00009-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Shen XY, Gao ZK, Han Y, Yuan M, Guo YS, Bi X. Activation and Role of Astrocytes in Ischemic Stroke. Front Cell Neurosci 2021; 15:755955. [PMID: 34867201 PMCID: PMC8635513 DOI: 10.3389/fncel.2021.755955] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 10/22/2021] [Indexed: 12/21/2022] Open
Abstract
Ischemic stroke refers to the disorder of blood supply of local brain tissue caused by various reasons. It has high morbidity and mortality worldwide. Astrocytes are the most abundant glial cells in the central nervous system (CNS). They are responsible for the homeostasis, nutrition, and protection of the CNS and play an essential role in many nervous system diseases’ physiological and pathological processes. After stroke injury, astrocytes are activated and play a protective role through the heterogeneous and gradual changes of their gene expression, morphology, proliferation, and function, that is, reactive astrocytes. However, the position of reactive astrocytes has always been a controversial topic. Many studies have shown that reactive astrocytes are a double-edged sword with both beneficial and harmful effects. It is worth noting that their different spatial and temporal expression determines astrocytes’ various functions. Here, we comprehensively review the different roles and mechanisms of astrocytes after ischemic stroke. In addition, the intracellular mechanism of astrocyte activation has also been involved. More importantly, due to the complex cascade reaction and action mechanism after ischemic stroke, the role of astrocytes is still difficult to define. Still, there is no doubt that astrocytes are one of the critical factors mediating the deterioration or improvement of ischemic stroke.
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Affiliation(s)
- Xin-Ya Shen
- Graduate School of Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Zhen-Kun Gao
- Graduate School of Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yu Han
- Department of Sport Rehabilitation, Shanghai University of Sport, Shanghai, China
| | - Mei Yuan
- Department of Sport Rehabilitation, Shanghai University of Sport, Shanghai, China
| | - Yi-Sha Guo
- Department of Sport Rehabilitation, Shanghai University of Sport, Shanghai, China
| | - Xia Bi
- Department of Rehabilitation Medicine, Shanghai University of Medicine and Health Sciences Affiliated Zhoupu Hospital, Shanghai, China
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Astrocyte Gliotransmission in the Regulation of Systemic Metabolism. Metabolites 2021; 11:metabo11110732. [PMID: 34822390 PMCID: PMC8623475 DOI: 10.3390/metabo11110732] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 12/28/2022] Open
Abstract
Normal brain function highly relies on the appropriate functioning of astrocytes. These glial cells are strategically situated between blood vessels and neurons, provide significant substrate support to neuronal demand, and are sensitive to neuronal activity and energy-related molecules. Astrocytes respond to many metabolic conditions and regulate a wide array of physiological processes, including cerebral vascular remodeling, glucose sensing, feeding, and circadian rhythms for the control of systemic metabolism and behavior-related responses. This regulation ultimately elicits counterregulatory mechanisms in order to couple whole-body energy availability with brain function. Therefore, understanding the role of astrocyte crosstalk with neighboring cells via the release of molecules, e.g., gliotransmitters, into the parenchyma in response to metabolic and neuronal cues is of fundamental relevance to elucidate the distinct roles of these glial cells in the neuroendocrine control of metabolism. Here, we review the mechanisms underlying astrocyte-released gliotransmitters that have been reported to be crucial for maintaining homeostatic regulation of systemic metabolism.
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Akther S, Hirase H. Assessment of astrocytes as a mediator of memory and learning in rodents. Glia 2021; 70:1484-1505. [PMID: 34582594 DOI: 10.1002/glia.24099] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 09/15/2021] [Accepted: 09/16/2021] [Indexed: 12/26/2022]
Abstract
The classical view of astrocytes is that they provide supportive functions for neurons, transporting metabolites and maintaining the homeostasis of the extracellular milieu. This view is gradually changing with the advent of molecular genetics and optical methods allowing interrogation of selected cell types in live experimental animals. An emerging view that astrocytes additionally act as a mediator of synaptic plasticity and contribute to learning processes has gained in vitro and in vivo experimental support. Here we focus on the literature published in the past two decades to review the roles of astrocytes in brain plasticity in rodents, whereby the roles of neurotransmitters and neuromodulators are considered to be comparable to those in humans. We outline established inputs and outputs of astrocytes and discuss how manipulations of astrocytes have impacted the behavior in various learning paradigms. Multiple studies suggest that the contribution of astrocytes has a considerably longer time course than neuronal activation, indicating metabolic roles of astrocytes. We advocate that exploring upstream and downstream mechanisms of astrocytic activation will further provide insight into brain plasticity and memory/learning impairment.
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Affiliation(s)
- Sonam Akther
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hajime Hirase
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Orellana VP, Tittarelli A, Retamal MA. Connexins in melanoma: Potential role of Cx46 in its aggressiveness. Pigment Cell Melanoma Res 2021; 34:853-868. [PMID: 33140904 DOI: 10.1111/pcmr.12945] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 10/20/2020] [Accepted: 10/27/2020] [Indexed: 12/19/2022]
Abstract
Melanoma is the most aggressive skin cancer, and in metastatic advanced states, it is completely refractory to chemotherapy. Therefore, it is relevant to understand the molecular bases that rule their aggressiveness. Connexins (Cxs) are proteins that under normal physiological conditions participate in intercellular communication, via the exchange of signaling molecules between the cytoplasm and extracellular milieu and the exchange of ions/second messengers between the cytoplasm of contacting cells. These proteins have shown important roles in cancer progression, chemo- and radiotherapy resistance, and metastasis. Accordingly, Cx26 and Cx43 seem to play important roles in melanoma progression and metastasis. On the other hand, Cx46 is typically expressed in the eye lens, where it seems to be associated with oxidative stress protection in fiber lens cells. However, in the last decade, Cx46 expression has been associated with breast and brain cancers, due to its role in potentiation of both extracellular vesicle release and cancer stem cell-like properties. In this review, we analyzed a potential role of Cx46 as a new biomarker and therapeutic target in melanoma.
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Affiliation(s)
- Viviana P Orellana
- Universidad del Desarrollo. Centro de Fisiología Celular e Integrativa, Clinica Alemana Facultad de Medicina, Santiago, Chile
- Universidad del Desarrollo. Programa de Comunicación Celular en Cáncer, Clínica Alemana Facultad de Medicina, Santiago, Chile
| | - Andrés Tittarelli
- Programa Institucional de Fomento a la Investigación, Desarrollo e Innovación (PIDi), Universidad Tecnológica Metropolitana (UTEM), Santiago, Chile
| | - Mauricio A Retamal
- Universidad del Desarrollo. Centro de Fisiología Celular e Integrativa, Clinica Alemana Facultad de Medicina, Santiago, Chile
- Universidad del Desarrollo. Programa de Comunicación Celular en Cáncer, Clínica Alemana Facultad de Medicina, Santiago, Chile
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Uptake of Biotinylated Spermine in Astrocytes: Effect of Cx43 siRNA, HIV-Tat Protein and Polyamine Transport Inhibitor on Polyamine Uptake. Biomolecules 2021; 11:biom11081187. [PMID: 34439853 PMCID: PMC8391674 DOI: 10.3390/biom11081187] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/06/2021] [Accepted: 08/08/2021] [Indexed: 12/14/2022] Open
Abstract
Polyamines (PAs) are polycationic biomolecules containing multiple amino groups. Patients with HIV-associated neurocognitive disorder (HAND) have high concentrations of the polyamine N-acetylated spermine in their brain and cerebral spinal fluid (CSF) and have increased PA release from astrocytes. These effects are due to the exposure to HIV-Tat. In healthy adult brain, PAs are accumulated but not synthesized in astrocytes, suggesting that PAs must enter astrocytes to be N-acetylated and released. Therefore, we tested if Cx43 hemichannels (Cx43-HCs) are pathways for PA flux in control and HIV-Tat-treated astrocytes. We used biotinylated spermine (b-SPM) to examine polyamine uptake. We found that control astrocytes and those treated with siRNA-Cx43 took up b-SPM, similarly suggesting that PA uptake is via a transporter/channel other than Cx43-HCs. Surprisingly, astrocytes pretreated with both HIV-Tat and siRNA-Cx43 showed increased accumulation of b-SPM. Using a novel polyamine transport inhibitor (PTI), trimer 44NMe, we blocked b-SPM uptake, showing that PA uptake is via a PTI-sensitive transport mechanism such as organic cation transporter. Our data suggest that Cx43 HCs are not a major pathway for b-SPM uptake in the condition of normal extracellular calcium concentration but may be involved in the release of PAs to the extracellular space during viral infection.
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Retamal MA, Fernandez-Olivares A, Stehberg J. Over-activated hemichannels: A possible therapeutic target for human diseases. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166232. [PMID: 34363932 DOI: 10.1016/j.bbadis.2021.166232] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 07/21/2021] [Accepted: 07/26/2021] [Indexed: 12/14/2022]
Abstract
In our body, all the cells are constantly sharing chemical and electrical information with other cells. This intercellular communication allows them to respond in a concerted way to changes in the extracellular milieu. Connexins are transmembrane proteins that have the particularity of forming two types of channels; hemichannels and gap junction channels. Under normal conditions, hemichannels allow the controlled release of signaling molecules to the extracellular milieu. However, under certain pathological conditions, over-activated hemichannels can induce and/or exacerbate symptoms. In the last decade, great efforts have been put into developing new tools that can modulate these over-activated hemichannels. Small molecules, antibodies and mimetic peptides have shown a potential for the treatment of human diseases. In this review, we summarize recent findings in the field of hemichannel modulation via specific tools, and how these tools could improve patient outcome in certain pathological conditions.
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Affiliation(s)
- Mauricio A Retamal
- Universidad del Desarrollo, Programa de Comunicación Celular en Cáncer, Santiago, Chile; Universidad del Desarrollo, Centro de Fisiología Celular e Integrativa, Santiago, Chile.
| | | | - Jimmy Stehberg
- Laboratorio de Neurobiología, Instituto de Ciencias Biomédicas, Facultad de medicina y Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
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Sui S, Yu H, Wang X, Wang W, Yang X, Pan X, Zhou Q, Xin C, Du R, Wu S, Zhang J, Cao Q, Wang N, Kuehn MH, Zhu W. iPSC-Derived Trabecular Meshwork Cells Stimulate Endogenous TM Cell Division Through Gap Junction in a Mouse Model of Glaucoma. Invest Ophthalmol Vis Sci 2021; 62:28. [PMID: 34427623 PMCID: PMC8399400 DOI: 10.1167/iovs.62.10.28] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Purpose Decreased trabecular meshwork (TM) cellularity has been implicated as a major reason for TM dysfunction and aqueous humor (AH) outflow abnormalities in primary open angle glaucoma. We previously found that transplantation of induced pluripotent stem cell (iPSC)-derived TM cells can restore TM function and stimulate endogenous TM cell division. The goal of the present study is to investigate whether signaling via gap junctions is involved in this process. Methods Differentiated iPSCs were characterized morphologically, transcriptionally, and immunohistochemically. After purification, iPSC-TM were co-cultured with mouse TM (MTM) cells to mimic the transplantation procedure. Through the pharmacological antagonists and short hairpin RNA (shRNA) technique, the gap junction function in iPSC-based therapy was determined. Results In the co-culture system, iPSC-TM increase MTM cell division as well as transfer of Ca2+ to MTM. This effect was blocked by treatment with the gap junction inhibitors carbenoxolone (CBX) or flufenamic acid (FFA). The shRNA mediated knock down of connexin 43 (Cx43) expression in iPSC-TM also results in decreased Ca2+ transfer and lower MTM proliferation rates. In vivo, Cx43 downregulation in transplanted iPSC-TM weakened their regenerative role in an Ad5.myocilinY437H mouse model of glaucoma. Mice receiving these cells exhibited lower TM cellularity and higher intraocular pressure (IOP) than those receiving unmodified iPSC-TM. Conclusions Our findings reveal a crucial role of gap junction, especially Cx43, in iPSC-based TM regeneration, and provides insights to enhance the regenerative effect of iPSCs in glaucoma therapy.
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Affiliation(s)
- Shangru Sui
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, China
| | - Hongxia Yu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, China.,Affiliated Hospital of Qingdao University, Qingdao, China
| | - Xiangji Wang
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, China
| | - Wenyan Wang
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, China
| | - Xuejiao Yang
- Affiliated Hospital of Qingdao University, Qingdao, China
| | - Xiaojing Pan
- Qingdao Eye Hospital, Shandong Eye Institute, Shandong Academy of Medical Sciences, Qingdao, China
| | - Qingjun Zhou
- Qingdao Eye Hospital, Shandong Eye Institute, Shandong Academy of Medical Sciences, Qingdao, China
| | - Chen Xin
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Beijing, China
| | - Rong Du
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Beijing, China
| | - Shen Wu
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Beijing, China
| | - Jingxue Zhang
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Beijing, China
| | - Qilong Cao
- Qingdao Haier Biotech Co. Ltd., Qingdao, China
| | - Ningli Wang
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Beijing, China
| | - Markus H Kuehn
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, USA.,Center for the Prevention and Treatment of Visual Loss, Iowa City Veterans Affairs Medical Center, Iowa City, Iowa, USA
| | - Wei Zhu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao, China.,Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beijing University & Capital Medical University, Beijing, China
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47
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Sherwood MW, Oliet SHR, Panatier A. NMDARs, Coincidence Detectors of Astrocytic and Neuronal Activities. Int J Mol Sci 2021; 22:7258. [PMID: 34298875 PMCID: PMC8307462 DOI: 10.3390/ijms22147258] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/30/2021] [Accepted: 06/30/2021] [Indexed: 12/18/2022] Open
Abstract
Synaptic plasticity is an extensively studied cellular correlate of learning and memory in which NMDARs play a starring role. One of the most interesting features of NMDARs is their ability to act as a co-incident detector. It is unique amongst neurotransmitter receptors in this respect. Co-incident detection is possible because the opening of NMDARs requires membrane depolarisation and the binding of glutamate. Opening of NMDARs also requires a co-agonist. Although the dynamic regulation of glutamate and membrane depolarization have been well studied in coincident detection, the role of the co-agonist site is unexplored. It turns out that non-neuronal glial cells, astrocytes, regulate co-agonist availability, giving them the ability to influence synaptic plasticity. The unique morphology and spatial arrangement of astrocytes at the synaptic level affords them the capacity to sample and integrate information originating from unrelated synapses, regardless of any pre-synaptic and post-synaptic commonality. As astrocytes are classically considered slow responders, their influence at the synapse is widely recognized as modulatory. The aim herein is to reconsider the potential of astrocytes to participate directly in ongoing synaptic NMDAR activity and co-incident detection.
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Affiliation(s)
- Mark W. Sherwood
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, F-3300 Bordeaux, France;
| | | | - Aude Panatier
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, F-3300 Bordeaux, France;
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48
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Beltrán-Matas P, Hartveit E, Veruki ML. Different glutamate sources and endogenous co-agonists activate extrasynaptic NMDA receptors on amacrine cells of the rod pathway microcircuit. Eur J Neurosci 2021; 54:4456-4474. [PMID: 34048091 DOI: 10.1111/ejn.15325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/09/2021] [Accepted: 05/23/2021] [Indexed: 12/17/2022]
Abstract
The NMDA receptors (NMDARs) expressed by AII and A17 amacrine cells, the two main inhibitory interneurons of the rod pathway microcircuit in the mammalian retina, are exclusively extrasynaptic, activated by ambient levels of glutamate, and molecularly distinct, with AII and A17 amacrines expressing GluN2B- and GluN2A-containing receptors, respectively. This important sensory microcircuit thus provides a unique model to study the activation and function of extrasynaptic NMDARs. Here, we investigated the sources of glutamate and the endogenous co-agonists (d-serine or glycine) that activate these distinct populations of NMDARs. With acute slices from rat retina, we used whole-cell voltage-clamp recording and measurement of current noise to monitor levels of NMDAR activity. Pre-incubation of retina with bafilomycin A1 (an inhibitor of neurotransmitter uptake into synaptic vesicles) abolished NMDAR-mediated noise in AII, but not A17 amacrines, suggesting a vesicular source of glutamate activates AII NMDARs, whereas a non-vesicular source activates A17 NMDARs. Pre-incubation of retina with l-methionine sulfoximine (an inhibitor of glutamine synthetase) also abolished NMDAR-mediated noise in AII, but not A17 amacrines, suggesting a neuronal source of glutamate activates AII NMDARs, whereas a glial source activates A17 NMDARs. Enzymatic breakdown of d-serine reduced NMDAR-mediated noise in AII, but not A17 amacrines, suggesting d-serine is the endogenous co-agonist at AII, but not A17 NMDARs. Our results reveal unique characteristics of these two populations of extrasynaptic NMDARs. The differential and independent activation of these receptors is likely to provide specific contributions to the signal processing and plasticity of the cellular components of the rod pathway microcircuit.
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Affiliation(s)
| | - Espen Hartveit
- Department of Biomedicine, University of Bergen, Bergen, Norway
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49
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Mazaud D, Capano A, Rouach N. The many ways astroglial connexins regulate neurotransmission and behavior. Glia 2021; 69:2527-2545. [PMID: 34101261 DOI: 10.1002/glia.24040] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 05/17/2021] [Accepted: 05/21/2021] [Indexed: 12/18/2022]
Abstract
Astrocytes have emerged as major players in the brain, contributing to many functions such as energy supply, neurotransmission, and behavior. They accomplish these functions in part via their capacity to form widespread intercellular networks and to release neuroactive factors, which can modulate neurotransmission at different levels, from individual synapses to neuronal networks. The extensive network communication of astrocytes is primarily mediated by gap junction channels composed of two connexins, Cx30 and Cx43, which present distinct temporal and spatial expression patterns. Yet, astroglial connexins are also involved in direct exchange with the extracellular space via hemichannels, as well as in adhesion and signaling processes via unconventional nonchannel functions. Accumulating evidence indicate that astrocytes modulate neurotransmission and behavior through these diverse connexin functions. We here review the many ways astroglial connexins regulate neuronal activity from the molecular level to behavior.
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Affiliation(s)
- David Mazaud
- Neuroglial Interactions in Cerebral Physiology and Pathologies, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Anna Capano
- Neuroglial Interactions in Cerebral Physiology and Pathologies, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France.,Doctoral School N°158, Sorbonne University, Paris, France
| | - Nathalie Rouach
- Neuroglial Interactions in Cerebral Physiology and Pathologies, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
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50
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Connexins in the Heart: Regulation, Function and Involvement in Cardiac Disease. Int J Mol Sci 2021; 22:ijms22094413. [PMID: 33922534 PMCID: PMC8122935 DOI: 10.3390/ijms22094413] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/12/2021] [Accepted: 04/20/2021] [Indexed: 12/20/2022] Open
Abstract
Connexins are a family of transmembrane proteins that play a key role in cardiac physiology. Gap junctional channels put into contact the cytoplasms of connected cardiomyocytes, allowing the existence of electrical coupling. However, in addition to this fundamental role, connexins are also involved in cardiomyocyte death and survival. Thus, chemical coupling through gap junctions plays a key role in the spreading of injury between connected cells. Moreover, in addition to their involvement in cell-to-cell communication, mounting evidence indicates that connexins have additional gap junction-independent functions. Opening of unopposed hemichannels, located at the lateral surface of cardiomyocytes, may compromise cell homeostasis and may be involved in ischemia/reperfusion injury. In addition, connexins located at non-canonical cell structures, including mitochondria and the nucleus, have been demonstrated to be involved in cardioprotection and in regulation of cell growth and differentiation. In this review, we will provide, first, an overview on connexin biology, including their synthesis and degradation, their regulation and their interactions. Then, we will conduct an in-depth examination of the role of connexins in cardiac pathophysiology, including new findings regarding their involvement in myocardial ischemia/reperfusion injury, cardiac fibrosis, gene transcription or signaling regulation.
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