1
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McInvale JJ, Kuper LC, Li E, Bonanno J, Lorman D, Gumenick R, Vincenti SL, Newman LA. Estradiol effects on astrocytic aquaporin 4 and glutamate transporter 1 expression contribute to shifts in brain dynamics supporting spatial working memory. Behav Brain Res 2025; 487:115578. [PMID: 40199402 DOI: 10.1016/j.bbr.2025.115578] [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: 12/31/2024] [Revised: 03/04/2025] [Accepted: 04/04/2025] [Indexed: 04/10/2025]
Abstract
Estrogenic effects on astrocytes improve glutamate recycling and water homeostasis for neuroprotection in pathology. Estrogens also enhance spatial learning and memory. The current study looked at the effect of 17β-estradiol (E2) on astrocytic glutamate transporter 1 (GLT-1) and aquaporin 4 (AQP4) in the prelimbic cortex (PrL) and dorsal hippocampus (dHC), areas active in spatial (allocentric) working memory in comparison to dorsolateral striatum (dlStr) which is involved in response or egocentric learning. Ovariectomized, female, Long Evans rats received 0, 4.5 µg/kg, or 45 µg/kg of E2 in a sesame oil vehicle 24 and 48 h prior to a delayed spontaneous alternation task (dSA). In line with previous research dSA performance significantly improved with administration of E2 as compared to sesame oil vehicle. AQP4 and GLT-1 levels were brain area specific and E2 enhanced AQP4 and GLT-1 in brain areas associated with spatial working memory (PrL and dHC) as compared to dlStr. Additionally, AQP4 was found to have the highest density in the unmyelinated axon rich hilus while GLT-1 showed the highest density in the synaptically dense molecular layer. However, AQP4 density in the stratum radiatum was similar to the hilus after dSA, potentially supporting dynamic changes in AQP4 response to natural cognitive activity. Hilar and prelimbic AQP4 area stained was also negatively correlated with performance on the dSA, which supports the theory of increased polarity of AQP4 with healthy cognitive function. These data suggest astrocytic water and glutamate homeostasis shift with high levels of estrogens to support spatial strategies.
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Affiliation(s)
- Julie J McInvale
- Department of Psychological Science, Neuroscience and Behavior Program, Vassar College, Poughkeepsie, NY, USA
| | - Louisa C Kuper
- Department of Psychological Science, Neuroscience and Behavior Program, Vassar College, Poughkeepsie, NY, USA
| | - Evelyn Li
- Department of Psychological Science, Neuroscience and Behavior Program, Vassar College, Poughkeepsie, NY, USA
| | - James Bonanno
- Department of Psychological Science, Neuroscience and Behavior Program, Vassar College, Poughkeepsie, NY, USA
| | - Daniella Lorman
- Department of Psychological Science, Neuroscience and Behavior Program, Vassar College, Poughkeepsie, NY, USA
| | - Ruby Gumenick
- Department of Psychological Science, Neuroscience and Behavior Program, Vassar College, Poughkeepsie, NY, USA
| | - Sydney L Vincenti
- Department of Psychological Science, Neuroscience and Behavior Program, Vassar College, Poughkeepsie, NY, USA
| | - Lori A Newman
- Department of Psychological Science, Neuroscience and Behavior Program, Vassar College, Poughkeepsie, NY, USA.
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2
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Leek AN, Quinn JA, Krapf D, Tamkun MM. GLT-1a glutamate transporter nanocluster localization is associated with astrocytic actin and neuronal Kv2 clusters at sites of neuron-astrocyte contact. Front Cell Dev Biol 2024; 12:1334861. [PMID: 38362041 PMCID: PMC10867268 DOI: 10.3389/fcell.2024.1334861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 01/16/2024] [Indexed: 02/17/2024] Open
Abstract
Introduction: Astrocytic GLT-1 glutamate transporters ensure the fidelity of glutamic neurotransmission by spatially and temporally limiting glutamate signals. The ability to limit neuronal hyperactivity relies on the localization and diffusion of GLT-1 on the astrocytic surface, however, little is known about the underlying mechanisms. We show that two isoforms of GLT-1, GLT-1a and GLT-1b, form nanoclusters on the surface of transfected astrocytes and HEK-293 cells. Methods: We used both fixed and live cell super-resolution imaging of fluorescent protein and epitope tagged proteins in co-cultures of rat astrocytes and neurons. Immunofluorescence techniques were also used. GLT1 diffusion was assessed via single particle tracking and fluorescence recovery after photobleach (FRAP). Results: We found GLT-1a, but not GLT-1b, nanoclusters concentrated adjacent to actin filaments which was maintained after addition of glutamate. GLT-1a nanocluster concentration near actin filaments was prevented by expression of a cytosolic GLT-1a C-terminus, suggesting the C-terminus is involved in the localization adjacent to cortical actin. Using super-resolution imaging, we show that astrocytic GLT-1a and actin co-localize in net-like structures around neuronal Kv2.1 clusters at points of neuron/astrocyte contact. Conclusion: Overall, these data describe a novel relationship between GLT-1a and cortical actin filaments, which localizes GLT-1a near neuronal structures responsive to ischemic insult.
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Affiliation(s)
- Ashley N. Leek
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, United States
- Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, CO, United States
| | - Josiah A. Quinn
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, United States
| | - Diego Krapf
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, CO, United States
| | - Michael M. Tamkun
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, United States
- Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, CO, United States
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, United States
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3
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Krassnitzer M, Boisvert B, Beiersdorf J, Harkany T, Keimpema E. Resident Astrocytes can Limit Injury to Developing Hippocampal Neurons upon THC Exposure. Neurochem Res 2023; 48:1242-1253. [PMID: 36482034 PMCID: PMC10030412 DOI: 10.1007/s11064-022-03836-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 11/21/2022] [Accepted: 11/25/2022] [Indexed: 12/13/2022]
Abstract
Cannabis legalization prompted the dilemma if plant-derived recreational drugs can have therapeutic potential and, consequently, how to address their regulation and safe distribution. In parallel, the steady worldwide decriminalization of cannabis and the enhanced content of its main psychoactive compound Δ9-tetrahydrocannabinol (THC), exposes populations to increasing amounts of cannabis and THC across all ages. While adverse effects of cannabis during critical stages of fetal neurodevelopment are investigated, these studies center on neurons alone. Thus, a gap of knowledge exists on how intercellular interactions between neighboring cell types, particularly astrocytes and neurons, could modify THC action. Here, we combine transcriptome analysis, transgenic models, high resolution microscopy and live cell imaging to demonstrate that hippocampal astrocytes accumulate in the strata radiatum and lacunosum moleculare of the CA1 subfield, containing particularly sensitive neurons to stressors, upon long term postnatal THC exposure in vivo. As this altered distribution is not dependent on cell proliferation, we propose that resident astrocytes accumulate in select areas to protect pyramidal neurons and their neurite extensions from pathological damage. Indeed, we could recapitulate the neuroprotective effect of astrocytes in vitro, as their physical presence significantly reduced the death of primary hippocampal neurons upon THC exposure (> 5 µM). Even so, astrocytes are also affected by a reduced metabolic readiness to stressors, as reflected by a downregulation of mitochondrial proteins. Thus, we find that astrocytes exert protective functions on local neurons during THC exposure, even though their mitochondrial electron transport chain is disrupted.
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Affiliation(s)
- Maria Krassnitzer
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Brooke Boisvert
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Johannes Beiersdorf
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Tibor Harkany
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
- Department of Neuroscience, Karolinska Institutet, Biomedicum 7D, Solna, Sweden
| | - Erik Keimpema
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria.
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4
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Rǎdulescu AR, Todd GC, Williams CL, Bennink BA, Lemus AA, Chesbro HE, Bourgeois JR, Kopec AM, Zuloaga DG, Scimemi A. Estimating the glutamate transporter surface density in distinct sub-cellular compartments of mouse hippocampal astrocytes. PLoS Comput Biol 2022; 18:e1009845. [PMID: 35120128 PMCID: PMC8849624 DOI: 10.1371/journal.pcbi.1009845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 02/16/2022] [Accepted: 01/18/2022] [Indexed: 11/19/2022] Open
Abstract
Glutamate transporters preserve the spatial specificity of synaptic transmission by limiting glutamate diffusion away from the synaptic cleft, and prevent excitotoxicity by keeping the extracellular concentration of glutamate at low nanomolar levels. Glutamate transporters are abundantly expressed in astrocytes, and previous estimates have been obtained about their surface expression in astrocytes of the rat hippocampus and cerebellum. Analogous estimates for the mouse hippocampus are currently not available. In this work, we derive the surface density of astrocytic glutamate transporters in mice of different ages via quantitative dot blot. We find that the surface density of glial glutamate transporters is similar in 7-8 week old mice and rats. In mice, the levels of glutamate transporters increase until about 6 months of age and then begin to decline slowly. Our data, obtained from a combination of experimental and modeling approaches, point to the existence of stark differences in the density of expression of glutamate transporters across different sub-cellular compartments, indicating that the extent to which astrocytes limit extrasynaptic glutamate diffusion depends not only on their level of synaptic coverage, but also on the identity of the astrocyte compartment in contact with the synapse. Together, these findings provide information on how heterogeneity in the spatial distribution of glutamate transporters in the plasma membrane of hippocampal astrocytes my alter glutamate receptor activation out of the synaptic cleft.
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Affiliation(s)
- Anca R. Rǎdulescu
- Department of Mathematics, State University of New York at New Paltz, New Paltz, New York, United States of America
| | - Gabrielle C. Todd
- Department of Biology, State University of New York at Albany, Albany, New York, United States of America
| | - Cassandra L. Williams
- Department of Mathematics, State University of New York at New Paltz, New Paltz, New York, United States of America
| | - Benjamin A. Bennink
- Department of Biology, State University of New York at Albany, Albany, New York, United States of America
| | - Alex A. Lemus
- Department of Biology, State University of New York at Albany, Albany, New York, United States of America
| | - Haley E. Chesbro
- Department of Biology, State University of New York at Albany, Albany, New York, United States of America
| | - Justin R. Bourgeois
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, United States of America
| | - Ashley M. Kopec
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, New York, United States of America
| | - Damian G. Zuloaga
- Department of Psychology, State University of New York at Albany, Albany, New York, United States of America
| | - Annalisa Scimemi
- Department of Biology, State University of New York at Albany, Albany, New York, United States of America
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5
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Bhat S, El-Kasaby A, Freissmuth M, Sucic S. Functional and Biochemical Consequences of Disease Variants in Neurotransmitter Transporters: A Special Emphasis on Folding and Trafficking Deficits. Pharmacol Ther 2020; 222:107785. [PMID: 33310157 PMCID: PMC7612411 DOI: 10.1016/j.pharmthera.2020.107785] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 12/02/2020] [Indexed: 01/30/2023]
Abstract
Neurotransmitters, such as γ-aminobutyric acid, glutamate, acetyl choline, glycine and the monoamines, facilitate the crosstalk within the central nervous system. The designated neurotransmitter transporters (NTTs) both release and take up neurotransmitters to and from the synaptic cleft. NTT dysfunction can lead to severe pathophysiological consequences, e.g. epilepsy, intellectual disability, or Parkinson’s disease. Genetic point mutations in NTTs have recently been associated with the onset of various neurological disorders. Some of these mutations trigger folding defects in the NTT proteins. Correct folding is a prerequisite for the export of NTTs from the endoplasmic reticulum (ER) and the subsequent trafficking to their pertinent site of action, typically at the plasma membrane. Recent studies have uncovered some of the key features in the molecular machinery responsible for transporter protein folding, e.g., the role of heat shock proteins in fine-tuning the ER quality control mechanisms in cells. The therapeutic significance of understanding these events is apparent from the rising number of reports, which directly link different pathological conditions to NTT misfolding. For instance, folding-deficient variants of the human transporters for dopamine or GABA lead to infantile parkinsonism/dystonia and epilepsy, respectively. From a therapeutic point of view, some folding-deficient NTTs are amenable to functional rescue by small molecules, known as chemical and pharmacological chaperones.
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Affiliation(s)
- Shreyas Bhat
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Ali El-Kasaby
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria.
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6
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He S, Zhang W, Zhang X, Xu P, Hong M, Qu S. The 4b-4c loop of excitatory amino acid transporter 1 containing four critical residues essential for substrate transport. J Biomol Struct Dyn 2019; 38:3599-3609. [PMID: 31496428 DOI: 10.1080/07391102.2019.1664935] [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: 10/26/2022]
Abstract
In the mammalians, the 4b-4c loop of excitatory amino acid transporters (EAATs) spans more than 50 amino-acid residues that are absent in glutamate transporter homologue of Pyrococcus horikoshii (GltPh). This part of insertion is unique for metazoans and indispensable to the localization of EAATs. The excitatory amino acid transporter (EAAT) 1 is one of the two glial glutamate transporters, which are responsible for efficiently clearing glutamate from the synaptic cleft to prevent neurotoxicity and cell death. Although the crystal structure of EAAT1cryst (a human thermostable EAAT1) was resolved in 2017, the structure-function relationship of the 4b-4c loop has not been elucidated in EAAT1cryst. To investigate the role of the 4b-4c loop, we performed alanine-scanning mutagenesis in the mutants and observed dramatically decreased transport activities in T192A, Y194A, N242A, and G245A mutants. The surface expression of T192A and Y194A mutants even decreased by more than 80%, and most of them were detained in the cytoplasm. However, when T192 and Y194 were substituted with conservative residues, the transport activities and the surface expressions of T192S and Y194F were largely recovered, and their kinetic parameters (Km values) were comparable to the wild-type EAAT1 as well. In contrast, N242 and G245 substituted with conservative residues could not rescue the uptake function, suggesting that N242 and G245 may play irreplaceable roles in the glutamate uptake process. These results indicate that the 4b-4c loop of EAAT1 may not only affect the glutamate uptake activity, but also influence the surface localization of EAAT1 by T192 and Y194.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Suifen He
- Central Laboratory and Department of Neurology, Shunde Hospital, Southern Medical University (the First People's Hospital of Shunde Foshan), Foshan, Guangdong, China.,Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, Guangdong, China
| | - Wenlong Zhang
- Central Laboratory and Department of Neurology, Shunde Hospital, Southern Medical University (the First People's Hospital of Shunde Foshan), Foshan, Guangdong, China.,Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, Guangdong, China
| | - Xiuping Zhang
- Teaching Center of Experimental Medicine, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, China
| | - Pingyi Xu
- Department of Neurology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Mei Hong
- College of Life Science, South China Agricultural University, Guangzhou, Guangdong, China
| | - Shaogang Qu
- Central Laboratory and Department of Neurology, Shunde Hospital, Southern Medical University (the First People's Hospital of Shunde Foshan), Foshan, Guangdong, China.,Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, Guangdong, China
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7
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Hayashi MK, Nishioka T, Shimizu H, Takahashi K, Kakegawa W, Mikami T, Hirayama Y, Koizumi S, Yoshida S, Yuzaki M, Tammi M, Sekino Y, Kaibuchi K, Shigemoto-Mogami Y, Yasui M, Sato K. Hyaluronan synthesis supports glutamate transporter activity. J Neurochem 2019; 150:249-263. [PMID: 31188471 DOI: 10.1111/jnc.14791] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 05/29/2019] [Accepted: 06/06/2019] [Indexed: 11/28/2022]
Abstract
Hyaluronan is synthesized, secreted, and anchored by hyaluronan synthases (HAS) at the plasma membrane and comprises the backbone of perineuronal nets around neuronal soma and dendrites. However, the molecular targets of hyaluronan to regulate synaptic transmission in the central nervous system have not been fully identified. Here, we report that hyaluronan is a negative regulator of excitatory signals. At excitatory synapses, glutamate is removed by glutamate transporters to turn off the signal and prevent excitotoxicity. Hyaluronan synthesized by HAS supports the activity of glial glutamate transporter 1 (GLT1). GLT1 also retracted from cellular processes of cultured astrocytes after hyaluronidase treatment and hyaluronan synthesis inhibition. A serial knockout study showed that all three HAS subtypes recruit GLT1 to cellular processes. Furthermore, hyaluronidase treatment activated neurons in a dissociated rat hippocampal culture and caused neuronal damage due to excitotoxicity. Our findings reveal that hyaluronan helps to turn off excitatory signals by supporting glutamate clearance. Cover Image for this issue: doi: 10.1111/jnc.14516.
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Affiliation(s)
- Mariko Kato Hayashi
- Medical School, International University of Health and Welfare, Narita, Chiba, Japan.,Division of Pharmacology, Laboratory of Neuropharmacology, National Institute of Health Sciences, Kawasaki, Kanagawa, Japan.,Department of Pharmacology, Keio University School of Medicine, Tokyo, Japan.,Department of Physiology, Keio University School of Medicine, Tokyo, Japan
| | - Tomoki Nishioka
- Department of Cell Pharmacology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
| | - Hideo Shimizu
- Division of Pharmacology, Laboratory of Neuropharmacology, National Institute of Health Sciences, Kawasaki, Kanagawa, Japan
| | - Kanako Takahashi
- Division of Pharmacology, Laboratory of Neuropharmacology, National Institute of Health Sciences, Kawasaki, Kanagawa, Japan
| | - Wataru Kakegawa
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan
| | - Tetsuri Mikami
- Department of Environmental and Life Sciences, Toyohashi University of Technology, Toyohashi, Aichi, Japan
| | - Yuri Hirayama
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Chuo, Yamanashi, Japan
| | - Schuichi Koizumi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Chuo, Yamanashi, Japan
| | - Sachiko Yoshida
- Department of Environmental and Life Sciences, Toyohashi University of Technology, Toyohashi, Aichi, Japan
| | - Michisuke Yuzaki
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan
| | - Markku Tammi
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, Kuopio, Finland
| | - Yuko Sekino
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan
| | - Kozo Kaibuchi
- Department of Cell Pharmacology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
| | - Yukari Shigemoto-Mogami
- Division of Pharmacology, Laboratory of Neuropharmacology, National Institute of Health Sciences, Kawasaki, Kanagawa, Japan
| | - Masato Yasui
- Department of Pharmacology, Keio University School of Medicine, Tokyo, Japan
| | - Kaoru Sato
- Division of Pharmacology, Laboratory of Neuropharmacology, National Institute of Health Sciences, Kawasaki, Kanagawa, Japan
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8
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Knockdown of the neuronal gene Lim3 at the early stages of development affects mitochondrial function and lifespan in Drosophila. Mech Ageing Dev 2019; 181:29-41. [DOI: 10.1016/j.mad.2019.111121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 04/29/2019] [Accepted: 05/30/2019] [Indexed: 01/08/2023]
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9
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Wu YW, Gordleeva S, Tang X, Shih PY, Dembitskaya Y, Semyanov A. Morphological profile determines the frequency of spontaneous calcium events in astrocytic processes. Glia 2018; 67:246-262. [DOI: 10.1002/glia.23537] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 08/19/2018] [Accepted: 09/03/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Yu-Wei Wu
- Brain Science Institute (BSI), RIKEN; Wako-shi Saitama Japan
- Institute of Molecular Biology, Academia Sinica; Nankang Taipei Taiwan
| | - Susan Gordleeva
- Institute of Neuroscience, University of Nizhny Novgorod; Nizhny Novgorod Russia
| | - Xiaofang Tang
- Brain Science Institute (BSI), RIKEN; Wako-shi Saitama Japan
| | - Pei-Yu Shih
- Brain Science Institute (BSI), RIKEN; Wako-shi Saitama Japan
| | - Yulia Dembitskaya
- Brain Science Institute (BSI), RIKEN; Wako-shi Saitama Japan
- Institute of Neuroscience, University of Nizhny Novgorod; Nizhny Novgorod Russia
| | - Alexey Semyanov
- Brain Science Institute (BSI), RIKEN; Wako-shi Saitama Japan
- Institute of Neuroscience, University of Nizhny Novgorod; Nizhny Novgorod Russia
- Department of Molecular Neurobiology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences; Moscow Russia
- All-Russian Research Institute of Medicinal and Aromatic Plants; Moscow Russia
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10
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Hayashi MK. Structure-Function Relationship of Transporters in the Glutamate-Glutamine Cycle of the Central Nervous System. Int J Mol Sci 2018; 19:ijms19041177. [PMID: 29649168 PMCID: PMC5979278 DOI: 10.3390/ijms19041177] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/09/2018] [Accepted: 04/10/2018] [Indexed: 12/12/2022] Open
Abstract
Many kinds of transporters contribute to glutamatergic excitatory synaptic transmission. Glutamate is loaded into synaptic vesicles by vesicular glutamate transporters to be released from presynaptic terminals. After synaptic vesicle release, glutamate is taken up by neurons or astrocytes to terminate the signal and to prepare for the next signal. Glutamate transporters on the plasma membrane are responsible for transporting glutamate from extracellular fluid to cytoplasm. Glutamate taken up by astrocyte is converted to glutamine by glutamine synthetase and transported back to neurons through glutamine transporters on the plasma membranes of the astrocytes and then on neurons. Glutamine is converted back to glutamate by glutaminase in the neuronal cytoplasm and then loaded into synaptic vesicles again. Here, the structures of glutamate transporters and glutamine transporters, their conformational changes, and how they use electrochemical gradients of various ions for substrate transport are summarized. Pharmacological regulations of these transporters are also discussed.
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Affiliation(s)
- Mariko Kato Hayashi
- School of Medicine, International University of Health and Welfare, 4-3 Kozunomori, Narita, Chiba 286-8686, Japan.
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11
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Kovermann P, Hessel M, Kortzak D, Jen JC, Koch J, Fahlke C, Freilinger T. Impaired K + binding to glial glutamate transporter EAAT1 in migraine. Sci Rep 2017; 7:13913. [PMID: 29066757 PMCID: PMC5654970 DOI: 10.1038/s41598-017-14176-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 10/06/2017] [Indexed: 12/28/2022] Open
Abstract
SLC1A3 encodes the glial glutamate transporter hEAAT1, which removes glutamate from the synaptic cleft via stoichiometrically coupled Na+-K+-H+-glutamate transport. In a young man with migraine with aura including hemiplegia, we identified a novel SLC1A3 mutation that predicts the substitution of a conserved threonine by proline at position 387 (T387P) in hEAAT1. To evaluate the functional effects of the novel variant, we expressed the wildtype or mutant hEAAT1 in mammalian cells and performed whole-cell patch clamp, fast substrate application, and biochemical analyses. T387P diminishes hEAAT1 glutamate uptake rates and reduces the number of hEAAT1 in the surface membrane. Whereas hEAAT1 anion currents display normal ligand and voltage dependence in cells internally dialyzed with Na+-based solution, no anion currents were observed with internal K+. Fast substrate application demonstrated that T387P abolishes K+-bound retranslocation. Our finding expands the phenotypic spectrum of genetic variation in SLC1A3 and highlights impaired K+ binding to hEAAT1 as a novel mechanism of glutamate transport dysfunction in human disease.
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Affiliation(s)
- Peter Kovermann
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, Jülich, Germany
| | - Margarita Hessel
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, Jülich, Germany
| | - Daniel Kortzak
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, Jülich, Germany
| | - Joanna C Jen
- Departments of Neurology and Neurobiology, UCLA School of Medicine, Los Angeles, USA
| | - Johannes Koch
- Department of Paediatrics, Salzburger Universitätsklinikum, Salzburg, Austria
| | - Christoph Fahlke
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, Jülich, Germany
| | - Tobias Freilinger
- Department of Neurology and Epileptology, Hertie-Institute for Clinical Brain Research (HIH), Tübingen, Germany.
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12
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Wang H, Wang S, Zhang K, Wang H, Lan L, Ma X, Liu X, Zhang S, Zheng J, Wei X, Yan H. Aquaporin 4 Forms a Macromolecular Complex with Glutamate Transporter 1 and Mu Opioid Receptor in Astrocytes and Participates in Morphine Dependence. J Mol Neurosci 2017; 62:17-27. [PMID: 28341892 DOI: 10.1007/s12031-017-0905-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Accepted: 02/24/2017] [Indexed: 10/19/2022]
Abstract
The water channel aquaporin 4 (AQP4) is abundantly expressed in astrocytes and provides a mechanism by which water permeability of the plasma membrane can be regulated. Evidence suggests that AQP4 is associated with glutamate transporter-1 (GLT-1) for glutamate clearance and contributes to morphine dependence. Previous studies show that AQP4 deficiency changed the mu opioid receptor expression and opioid receptors' characteristics as well. In this study, we focused on whether AQP4 could form macromolecular complex with GLT-1 and mu opioid receptor (MOR) and participates in morphine dependence. By using immunofluorescence staining, fluorescence resonance energy transfer, and co-immunoprecipitation, we demonstrated that AQP4 forms protein complexes with GLT-1 and MOR in both brain tissue and primary cultured astrocytes. We then showed that the C-terminus of AQP4 containing the amino acid residues 252 to 323 is the site of interaction with GLT-1. Protein kinase C, activated by morphine, played an important role in regulating the expression of these proteins. These findings may help to reveal the mechanism that AQP4, GLT-1, and MOR form protein complex and participate in morphine dependence, and deeply understand the reason that AQP4 deficiency maintains extracellular glutamate homeostasis and attenuates morphine dependence, moreover emphasizes the function of astrocyte in morphine dependence.
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Affiliation(s)
- Hui Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Shiqi Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Kang Zhang
- State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Hua Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Liting Lan
- State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Xiaoyun Ma
- State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Xiaoyan Liu
- State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Shuzhuo Zhang
- State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Jianquan Zheng
- State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China
| | - Xiaoli Wei
- State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China.
| | - Haitao Yan
- State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China.
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Frago LM, Chowen JA. Involvement of Astrocytes in Mediating the Central Effects of Ghrelin. Int J Mol Sci 2017; 18:ijms18030536. [PMID: 28257088 PMCID: PMC5372552 DOI: 10.3390/ijms18030536] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 02/16/2017] [Accepted: 02/25/2017] [Indexed: 12/31/2022] Open
Abstract
Although astrocytes are the most abundant cells in the mammalian brain, much remains to be learned about their molecular and functional features. Astrocytes express receptors for numerous hormones and metabolic factors, including the appetite-promoting hormone ghrelin. The metabolic effects of ghrelin are largely opposite to those of leptin, as it stimulates food intake and decreases energy expenditure. Ghrelin is also involved in glucose-sensing and glucose homeostasis. The widespread expression of the ghrelin receptor in the central nervous system suggests that this hormone is not only involved in metabolism, but also in other essential functions in the brain. In fact, ghrelin has been shown to promote cell survival and neuroprotection, with some studies exploring the use of ghrelin as a therapeutic agent against metabolic and neurodegenerative diseases. In this review, we highlight the possible role of glial cells as mediators of ghrelin's actions within the brain.
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Affiliation(s)
- Laura M Frago
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación la Princesa, CIBER de Obesidad Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, 28009 Madrid, Spain.
- Department of Pediatrics, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
| | - Julie A Chowen
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación la Princesa, CIBER de Obesidad Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, 28009 Madrid, Spain.
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Purinergic P2Y1 Receptors Control Rapid Expression of Plasma Membrane Processes in Hippocampal Astrocytes. Mol Neurobiol 2016; 54:4081-4093. [PMID: 27318677 DOI: 10.1007/s12035-016-9955-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 06/06/2016] [Indexed: 10/21/2022]
Abstract
Astrocytes regulate neuronal activity and blood brain barrier through tiny plasma membrane branches or astrocytic processes (APs) making contact with synapses and brain vessels. Several transmitters released by astrocytes and exerting their action on several receptor classes expressed by astrocytes themselves influence their physiology. Here we found that APs are dynamically modulated by purines. In live imaging experiments carried out in rat hippocampal astrocytes, Gq-coupled P2Y1 receptor blockade with the selective antagonist MRS2179 (1 μM) or inhibition of its effector phospholipase C using U73122 (3 μM) produced APs retraction, while stimulation of the same receptor with the selective agonist 2MeSADP (100 μM) increased their number. Since astrocytes, among other transmitters, release ATP by several mechanisms including connexin hemichannels, we used the connexin hemichannel inhibitor carbenoxolone (100 μM) and APs retraction was observed. In our system we then measured expression or function of channels important for modulation of volume transmission and K+ buffering, aquaporin-4, and K+ inward rectifying (Kir) channels, respectively. Aquaporin-4 expression level did not change whereas, in whole-cell patch-clamp recordings performed to measure Kir current, we observed an increase in K+ current in all conditions where APs number was reduced. These data are supporting the idea of a dynamic modulation of astrocytic processes by purinergic signal, strengthening the role of purines in brain homeostasis.
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