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Shen W, Nwosu G, Honer M, Clasadonte J, Schmalzbauer S, Biven M, Langer K, Flamm C, Poliquin S, Mermer F, Dedeurwaerdere S, Hernandez MC, Kang JQ. γ-Aminobutyric acid transporter and GABA A receptor mechanisms in Slc6a1+/A288V and Slc6a1+/S295L mice associated with developmental and epileptic encephalopathies. Brain Commun 2024; 6:fcae110. [PMID: 38650830 PMCID: PMC11032196 DOI: 10.1093/braincomms/fcae110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 01/09/2024] [Accepted: 04/11/2024] [Indexed: 04/25/2024] Open
Abstract
We have previously characterized the molecular mechanisms for variants in γ-aminobutyric acid transporter 1-encoding solute carrier family 6-member 1 (SLC6A1) in vitro and concluded that a partial or complete loss of γ-aminobutyric acid uptake due to impaired protein trafficking is the primary aetiology. Impairment of γ-aminobutyric acid transporter 1 function could cause compensatory changes in the expression of γ-aminobutyric acid receptors, which, in turn, modify disease pathophysiology and phenotype. Here we used different approaches including radioactive 3H γ-aminobutyric acid uptake in cells and synaptosomes, immunohistochemistry and confocal microscopy as well as brain slice surface protein biotinylation to characterize Slc6a1+/A288V and Slc6a1+/S295L mice, representative of a partial or a complete loss of function of SLC6A1 mutations, respectively. We employed the γ-aminobutyric acid transporter 1-specific inhibitor [3H]tiagabine binding and GABAA receptor subunit-specific radioligand binding to profile the γ-aminobutyric acid transporter 1 and GABAA receptor expression in major brain regions such as cortex, cerebellum, hippocampus and thalamus. We also determined the total and surface expression of γ-aminobutyric acid transporter 1, γ-aminobutyric acid transporter 3 and expression of GABAA receptor in the major brain regions in the knockin mice. We found that γ-aminobutyric acid transporter 1 protein was markedly reduced in cortex, hippocampus, thalamus and cerebellum in both mutant mouse lines. Consistent with the findings of reduced γ-aminobutyric acid uptake for both γ-aminobutyric acid transporter 1(A288V) and γ-aminobutyric acid transporter 1(S295L), both the total and the γ-aminobutyric acid transporter 1-mediated 3H γ-aminobutyric acid reuptake was reduced. We found that γ-aminobutyric acid transporter 3 is only abundantly expressed in the thalamus and there was no compensatory increase of γ-aminobutyric acid transporter 3 in either of the mutant mouse lines. γ-Aminobutyric acid transporter 1 was reduced in both somatic regions and nonsomatic regions in both mouse models, in which a ring-like structure was identified only in the Slc6a1+/A288V mouse, suggesting more γ-aminobutyric acid transporter 1 retention inside endoplasmic reticulum in the Slc6a1+/A288V mouse. The [3H]tiagabine binding was similar in both mouse models despite the difference in γ-aminobutyric acid uptake function and γ-aminobutyric acid transporter 1 protein expression for both mutations. There were no differences in GABAA receptor subtype expression, except for a small increase in the expression of α5 subunits of GABAA receptor in the hippocampus of Slc6a1S295L homozygous mice, suggesting a potential interaction between the expression of this GABAA receptor subtype and the mutant γ-aminobutyric acid transporter 1. The study provides the first comprehensive characterization of the SLC6A1 mutations in vivo in two representative mouse models. Because both γ-aminobutyric acid transporter 1 and GABAA receptors are targets for anti-seizure medications, the findings from this study can help guide tailored treatment options based on the expression and function of γ-aminobutyric acid transporter 1 and GABAA receptor in SLC6A1 mutation-mediated neurodevelopmental and epileptic encephalopathies.
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Affiliation(s)
- Wangzhen Shen
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Gerald Nwosu
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Neuroscience Graduate Program, Vanderbilt University, Nashville, TN 37232, USA
- Vanderbilt Brain Institute, Nashville, TN 37240, USA
- Department of Biochemistry, Cancer Biology, Neuroscience and Pharmacology, Meharry Medical College, Nashville, TN 37232, USA
| | - Michael Honer
- Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Basel 4070, Switzerland
| | - Jerome Clasadonte
- Early Solutions, Neuroscience TA, UCB Biopharma SRL, Braine l’Alleud 1420, Belgium
| | - Svenja Schmalzbauer
- Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Basel 4070, Switzerland
| | - Marshall Biven
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Katherine Langer
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Carson Flamm
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Sarah Poliquin
- Neuroscience Graduate Program, Vanderbilt University, Nashville, TN 37232, USA
- Vanderbilt Brain Institute, Nashville, TN 37240, USA
| | - Felicia Mermer
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | | | - Maria-Clemencia Hernandez
- Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, Basel 4070, Switzerland
| | - Jing-Qiong Kang
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Brain Institute, Nashville, TN 37240, USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
- Vanderbilt Kennedy Center of Human Development, Nashville, TN 37232, USA
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Ali DN, Ali HM, Lopez MR, Kang S, Choi DS. Astrocytic GABAergic Regulation in Alcohol Use and Major Depressive Disorders. Cells 2024; 13:318. [PMID: 38391931 PMCID: PMC10887002 DOI: 10.3390/cells13040318] [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: 11/30/2023] [Revised: 01/26/2024] [Accepted: 02/06/2024] [Indexed: 02/24/2024] Open
Abstract
Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central nervous system (CNS). Most GABAergic neurons synthesize GABA from glutamate and release it in the synaptic cleft in the CNS. However, astrocytes can also synthesize and release GABA, activating GABA receptors in the neighboring neurons in physiological and pathological conditions. As the primary homeostatic glial cells in the brain, astrocytes play a crucial role in regulating GABA homeostasis and synaptic neurotransmission. Accumulating evidence demonstrates that astrocytic GABA dysregulation is implicated in psychiatric disorders, including alcohol use disorder (AUD) and major depressive disorder (MDD), the most prevalent co-occurring psychiatric disorders. Several current medications and emerging pharmacological agents targeting GABA levels are in clinical trials for treating AUD and MDD. This review offers a concise summary of the role of astrocytic GABA regulation in AUD and MDD. We also provide an overview of the current understanding and areas of debate regarding the mechanisms by which astrocytes regulate GABA in the CNS and their potential significance in the molecular basis of AUD and MDD, paving the way toward future research directions and potential therapeutic target areas within this field.
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Affiliation(s)
- Dina N. Ali
- Department of Molecular Pharmacology and Experimental Therapeutics, Rochester, MN 55905, USA; (D.N.A.); (H.M.A.); (M.R.L.); (S.K.)
| | - Hossam M. Ali
- Department of Molecular Pharmacology and Experimental Therapeutics, Rochester, MN 55905, USA; (D.N.A.); (H.M.A.); (M.R.L.); (S.K.)
| | - Matthew R. Lopez
- Department of Molecular Pharmacology and Experimental Therapeutics, Rochester, MN 55905, USA; (D.N.A.); (H.M.A.); (M.R.L.); (S.K.)
| | - Shinwoo Kang
- Department of Molecular Pharmacology and Experimental Therapeutics, Rochester, MN 55905, USA; (D.N.A.); (H.M.A.); (M.R.L.); (S.K.)
| | - Doo-Sup Choi
- Department of Molecular Pharmacology and Experimental Therapeutics, Rochester, MN 55905, USA; (D.N.A.); (H.M.A.); (M.R.L.); (S.K.)
- Neuroscience Program, Rochester, MN 55905, USA
- Department of Psychiatry and Psychology, Mayo Clinic College of Medicine and Science, Rochester, MN 55905, USA
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Di Palma M, Catalano M, Serpe C, De Luca M, Monaco L, Kunzelmann K, Limatola C, Conti F, Fattorini G. Lipopolysaccharide augments microglial GABA uptake by increasing GABA transporter-1 trafficking and bestrophin-1 expression. Glia 2023; 71:2527-2540. [PMID: 37431178 DOI: 10.1002/glia.24437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 06/16/2023] [Accepted: 06/22/2023] [Indexed: 07/12/2023]
Abstract
Gamma-aminobutyric acid (GABA), the principal inhibitory neurotransmitter in the brain, affects numerous immune cell functions. Microglia, the brain's resident innate immune cells, regulate GABA signaling through GABA receptors and express the complete GABAergic machinery for GABA synthesis, uptake, and release. Here, the use of primary microglial cell cultures and ex vivo brain tissue sections allowed for demonstrating that treatment with lipopolysaccharide (LPS) increased microglial GABA uptake as well as GABA transporter (GAT)-1 trafficking. This effect was not entirely abolished by treatment with GAT inhibitors (GAT-Is). Notably, LPS also induced microglial upregulation of bestrophin-1 (BEST-1), a Ca2+ -activated Cl- channel permeable to GABA. Combined administration of GAT-Is and a BEST-1 inhibitor completely abolished LPS-induced microglial GABA uptake. Interestingly, increased microglial GAT-1 membrane turnover via syntaxin 1A was detected in LPS-treated cultures after BEST-1 blockade. Altogether, these findings provided evidence for a novel mechanism through which LPS may trigger the inflammatory response by directly altering microglial GABA clearance and identified the GAT-1/BEST-1 interplay as a potential novel mechanism involved in brain inflammation.
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Affiliation(s)
- Michael Di Palma
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy
| | - Myriam Catalano
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Carmela Serpe
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Mariassunta De Luca
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Lucia Monaco
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Regensburg, Germany
| | - Cristina Limatola
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
- IRCCS Neuromed, Pozzilli, Italy
| | - Fiorenzo Conti
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy
- Center for Neurobiology of Aging, INRCA IRCCS, Ancona, Italy
- Fondazione di Medicina Molecolare, Università Politecnica delle Marche, Ancona, Italy
| | - Giorgia Fattorini
- Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Università Politecnica delle Marche, Ancona, Italy
- Center for Neurobiology of Aging, INRCA IRCCS, Ancona, Italy
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Koh W, Kwak H, Cheong E, Lee CJ. GABA tone regulation and its cognitive functions in the brain. Nat Rev Neurosci 2023; 24:523-539. [PMID: 37495761 DOI: 10.1038/s41583-023-00724-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2023] [Indexed: 07/28/2023]
Abstract
γ-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter released at GABAergic synapses, mediating fast-acting phasic inhibition. Emerging lines of evidence unequivocally indicate that a small amount of extracellular GABA - GABA tone - exists in the brain and induces a tonic GABA current that controls neuronal activity on a slow timescale relative to that of phasic inhibition. Surprisingly, studies indicate that glial cells that synthesize GABA, such as astrocytes, release GABA through non-vesicular mechanisms, such as channel-mediated release, and thereby act as the source of GABA tone in the brain. In this Review, we first provide an overview of major advances in our understanding of the cell-specific molecular and cellular mechanisms of GABA synthesis, release and clearance that regulate GABA tone in various brain regions. We next examine the diverse ways in which the tonic GABA current regulates synaptic transmission and synaptic plasticity through extrasynaptic GABAA-receptor-mediated mechanisms. Last, we discuss the physiological mechanisms through which tonic inhibition modulates cognitive function on a slow timescale. In this Review, we emphasize that the cognitive functions of tonic GABA current extend beyond mere inhibition, laying a foundation for future research on the physiological and pathophysiological roles of GABA tone regulation in normal and abnormal psychiatric conditions.
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Affiliation(s)
- Wuhyun Koh
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, South Korea
| | - Hankyul Kwak
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Eunji Cheong
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea.
| | - C Justin Lee
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, South Korea.
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Astrocytes regulate inhibitory neurotransmission through GABA uptake, metabolism, and recycling. Essays Biochem 2023; 67:77-91. [PMID: 36806927 DOI: 10.1042/ebc20220208] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 01/03/2023] [Accepted: 01/05/2023] [Indexed: 02/23/2023]
Abstract
Synaptic regulation of the primary inhibitory neurotransmitter γ-aminobutyric acid (GABA) is essential for brain function. Cerebral GABA homeostasis is tightly regulated through multiple mechanisms and is directly coupled to the metabolic collaboration between neurons and astrocytes. In this essay, we outline and discuss the fundamental roles of astrocytes in regulating synaptic GABA signaling. A major fraction of synaptic GABA is removed from the synapse by astrocytic uptake. Astrocytes utilize GABA as a metabolic substrate to support glutamine synthesis. The astrocyte-derived glutamine is subsequently transferred to neurons where it serves as the primary precursor of neuronal GABA synthesis. The flow of GABA and glutamine between neurons and astrocytes is collectively termed the GABA-glutamine cycle and is essential to sustain GABA synthesis and inhibitory signaling. In certain brain areas, astrocytes are even capable of synthesizing and releasing GABA to modulate inhibitory transmission. The majority of oxidative GABA metabolism in the brain takes place in astrocytes, which also leads to synthesis of the GABA-related metabolite γ-hydroxybutyric acid (GHB). The physiological roles of endogenous GHB remain unclear, but may be related to regulation of tonic inhibition and synaptic plasticity. Disrupted inhibitory signaling and dysfunctional astrocyte GABA handling are implicated in several diseases including epilepsy and Alzheimer's disease. Synaptic GABA homeostasis is under astrocytic control and astrocyte GABA uptake, metabolism, and recycling may therefore serve as relevant targets to ameliorate pathological inhibitory signaling.
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Bhatt M, Gauthier-Manuel L, Lazzarin E, Zerlotti R, Ziegler C, Bazzone A, Stockner T, Bossi E. A comparative review on the well-studied GAT1 and the understudied BGT-1 in the brain. Front Physiol 2023; 14:1145973. [PMID: 37123280 PMCID: PMC10137170 DOI: 10.3389/fphys.2023.1145973] [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: 01/16/2023] [Accepted: 03/30/2023] [Indexed: 05/02/2023] Open
Abstract
γ-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the central nervous system (CNS). Its homeostasis is maintained by neuronal and glial GABA transporters (GATs). The four GATs identified in humans are GAT1 (SLC6A1), GAT2 (SLC6A13), GAT3 (SLC6A11), and betaine/GABA transporter-1 BGT-1 (SLC6A12) which are all members of the solute carrier 6 (SLC6) family of sodium-dependent transporters. While GAT1 has been investigated extensively, the other GABA transporters are less studied and their role in CNS is not clearly defined. Altered GABAergic neurotransmission is involved in different diseases, but the importance of the different transporters remained understudied and limits drug targeting. In this review, the well-studied GABA transporter GAT1 is compared with the less-studied BGT-1 with the aim to leverage the knowledge on GAT1 to shed new light on the open questions concerning BGT-1. The most recent knowledge on transporter structure, functions, expression, and localization is discussed along with their specific role as drug targets for neurological and neurodegenerative disorders. We review and discuss data on the binding sites for Na+, Cl-, substrates, and inhibitors by building on the recent cryo-EM structure of GAT1 to highlight specific molecular determinants of transporter functions. The role of the two proteins in GABA homeostasis is investigated by looking at the transport coupling mechanism, as well as structural and kinetic transport models. Furthermore, we review information on selective inhibitors together with the pharmacophore hypothesis of transporter substrates.
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Affiliation(s)
- Manan Bhatt
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
- Centre for Neuroscience—University of Insubria, Varese, Italy
| | - Laure Gauthier-Manuel
- Department of Biophysics II/Structural Biology, University of Regensburg, Regensburg, Germany
| | - Erika Lazzarin
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Waehringerstr, Vienna
| | - Rocco Zerlotti
- Department of Biophysics II/Structural Biology, University of Regensburg, Regensburg, Germany
- Nanion Technologies GmbH, Munich, Germany
| | - Christine Ziegler
- Department of Biophysics II/Structural Biology, University of Regensburg, Regensburg, Germany
| | | | - Thomas Stockner
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Waehringerstr, Vienna
- *Correspondence: Thomas Stockner, ; Elena Bossi,
| | - Elena Bossi
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
- Centre for Neuroscience—University of Insubria, Varese, Italy
- *Correspondence: Thomas Stockner, ; Elena Bossi,
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Hasriadi, Dasuni Wasana PW, Suwattananuruk P, Thompho S, Thitikornpong W, Vajragupta O, Rojsitthisak P, Towiwat P. Curcumin Diethyl γ-Aminobutyrate, a Prodrug of Curcumin, for Enhanced Treatment of Inflammatory Pain. ACS Pharmacol Transl Sci 2022; 5:774-790. [PMID: 36110378 PMCID: PMC9469498 DOI: 10.1021/acsptsci.2c00062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Indexed: 11/30/2022]
Abstract
Curcumin is a naturally occurring polyphenol compound with potential analgesic effects. It has been shown to improve pain-like behaviors in numerous models of pain. Despite its potential, curcumin exhibits poor physicochemical and pharmacokinetic properties, which hinder its oral therapeutic efficacy. Curcumin diethyl γ-aminobutyrate (CUR-2GE), a carbamate prodrug of curcumin, was designed to overcome these limitations and demonstrated greater anti-neuroinflammatory effects compared to curcumin in vitro. Thus, this study evaluated the effect of CUR-2GE and its parent compound on pain-like behaviors in carrageenan- and LPS-induced mouse models. The possible side effects of CUR-2GE were also assessed by exploring its effects on motor coordination and spontaneous locomotor activity after acute and chronic treatments. The results showed that CUR-2GE improved mechanical and thermal hyperalgesia and locomotor activity to a greater extent than curcumin in carrageenan-induced mice. These results are in line with the ability of CUR-2GE to suppress peripheral inflammation in the paw tissue of carrageenan-induced mice, indicated by a significant decrease in TNF-α and IL-6 expression levels. Similarly, in LPS-induced mice, CUR-2GE improved sickness and pain-like behaviors (exploratory behaviors and long-term locomotor activity) to a greater extent than curcumin. Furthermore, CUR-2GE significantly reduced the level of proinflammatory cytokines in both the plasma and spinal cord tissue of LPS-induced mice, exhibiting significantly higher inhibition than curcumin. Moreover, the motor coordination, and locomotive behaviors of mice were not affected by both acute and chronic administration of CUR-2GE, indicating no potential CNS side effects. Thus, CUR-2GE demonstrated enhanced therapeutic efficacy in mouse models of inflammatory pain without any possible CNS side effects, suggesting its potential to be developed as an analgesic agent against inflammatory pain.
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Affiliation(s)
- Hasriadi
- Center of Excellence in Natural Products for Ageing and Chronic Diseases, Chulalongkorn University, Bangkok 10330, Thailand
- Department of Pharmacology and Physiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Peththa Wadu Dasuni Wasana
- Department of Pharmacology and Physiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
- Pharmaceutical Sciences and Technology Program, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Piyapan Suwattananuruk
- Pharmaceutical Sciences and Technology Program, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Somphob Thompho
- Pharmaceutical Research Instrument Center, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Worathat Thitikornpong
- Center of Excellence in Natural Products for Ageing and Chronic Diseases, Chulalongkorn University, Bangkok 10330, Thailand
- Department of Food and Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Opa Vajragupta
- Center of Excellence in Natural Products for Ageing and Chronic Diseases, Chulalongkorn University, Bangkok 10330, Thailand
- Molecular Probes for Imaging Research Network Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Pornchai Rojsitthisak
- Center of Excellence in Natural Products for Ageing and Chronic Diseases, Chulalongkorn University, Bangkok 10330, Thailand
- Department of Food and Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Pasarapa Towiwat
- Center of Excellence in Natural Products for Ageing and Chronic Diseases, Chulalongkorn University, Bangkok 10330, Thailand
- Department of Pharmacology and Physiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
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Andersen JV, Schousboe A, Verkhratsky A. Astrocyte energy and neurotransmitter metabolism in Alzheimer's disease: integration of the glutamate/GABA-glutamine cycle. Prog Neurobiol 2022; 217:102331. [PMID: 35872221 DOI: 10.1016/j.pneurobio.2022.102331] [Citation(s) in RCA: 55] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 07/14/2022] [Accepted: 07/19/2022] [Indexed: 02/06/2023]
Abstract
Astrocytes contribute to the complex cellular pathology of Alzheimer's disease (AD). Neurons and astrocytes function in close collaboration through neurotransmitter recycling, collectively known as the glutamate/GABA-glutamine cycle, which is essential to sustain neurotransmission. Neurotransmitter recycling is intimately linked to astrocyte energy metabolism. In the course of AD, astrocytes undergo extensive metabolic remodeling, which may profoundly affect the glutamate/GABA-glutamine cycle. The consequences of altered astrocyte function and metabolism in relation to neurotransmitter recycling are yet to be comprehended. Metabolic alterations of astrocytes in AD deprive neurons of metabolic support, thereby contributing to synaptic dysfunction and neurodegeneration. In addition, several astrocyte-specific components of the glutamate/GABA-glutamine cycle, including glutamine synthesis and synaptic neurotransmitter uptake, are perturbed in AD. Integration of the complex astrocyte biology within the context of AD is essential for understanding the fundamental mechanisms of the disease, while restoring astrocyte metabolism may serve as an approach to arrest or even revert clinical progression of AD.
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Affiliation(s)
- Jens V Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK; Achucarro Center for Neuroscience, IKERBASQUE, 48011 Bilbao, Spain; Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102 Vilnius, Lithuania.
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9
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Jithavech P, Suwattananuruk P, Hasriadi, Muangnoi C, Thitikornpong W, Towiwat P, Vajragupta O, Rojsitthisak P. Physicochemical investigation of a novel curcumin diethyl γ-aminobutyrate, a carbamate ester prodrug of curcumin with enhanced anti-neuroinflammatory activity. PLoS One 2022; 17:e0265689. [PMID: 35303012 PMCID: PMC9048745 DOI: 10.1371/journal.pone.0265689] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 03/05/2022] [Indexed: 12/28/2022] Open
Abstract
Curcumin is a polyphenol compound that alleviates several neuroinflammation-related diseases including Alzheimer's disease, Parkinson's disease, multiple sclerosis, epilepsy and cerebral injury. However, the therapeutic efficacy of curcumin is limited by its poor physicochemical properties. The present study aimed to develop a new carrier-linked curcumin prodrug, curcumin diethyl γ-aminobutyrate (CUR-2GE), with improved physicochemical and anti-neuroinflammatory properties. CUR-2GE was designed and synthesized by conjugating curcumin with gamma-aminobutyric acid ethyl ester (GE) via a carbamate linkage. The carbamate linkage was selected to increase stability at acidic pH while GE served as a promoiety for lipophilic enhancement. The synthesized CUR-2GE was investigated for solubility, partition coefficient, stability, and bioconversion. The solubility of CUR-2GE was less than 0.05 μg/mL similar to that of curcumin, while the lipophilicity with log P of 3.57 was significantly increased. CUR-2GE was resistant to chemical hydrolysis at acidic pH (pH 1.2 and 4.5) as anticipated but rapidly hydrolyzed at pH 6.8 and 7.4. The incomplete hydrolysis of CUR-2GE was observed in simulated gastrointestinal fluids which liberated the intermediate curcumin monoethyl γ-aminobutyric acid (CUR-1GE) and the parent curcumin. In plasma, CUR-2GE was sequentially converted to CUR-1GE and curcumin within 1 h. In lipopolysaccharide (LPS)-stimulated BV-2 microglial cells, CUR-2GE effectively attenuated the pro-inflammatory mediators by decreasing the secretion of nitric oxide and cytokines (TNF-α and IL-6) to a greater extent than curcumin due to an increase in cellular uptake. Altogether, the newly developed acid-stable CUR-2GE prodrug is a potential pre-clinical and clinical candidate for further evaluation on neuroprotective and anti-neuroinflammatory effects.
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Affiliation(s)
- Ponsiree Jithavech
- Center of Excellence in Natural Products for Ageing and Chronic Diseases,
Chulalongkorn University, Bangkok, Thailand
- Department of Food and Pharmaceutical Chemistry, Faculty of
Pharmaceutical Sciences, Chulalongkorn University, Bangkok,
Thailand
| | - Piyapan Suwattananuruk
- Center of Excellence in Natural Products for Ageing and Chronic Diseases,
Chulalongkorn University, Bangkok, Thailand
- Pharmaceutical Sciences and Technology Program, Faculty of Pharmaceutical
Sciences, Chulalongkorn University, Bangkok, Thailand
| | - Hasriadi
- Pharmaceutical Sciences and Technology Program, Faculty of Pharmaceutical
Sciences, Chulalongkorn University, Bangkok, Thailand
| | - Chawanphat Muangnoi
- Cell and Animal Model Unit, Institute of Nutrition, Mahidol University,
Nakhon Pathom, Thailand
| | - Worathat Thitikornpong
- Center of Excellence in Natural Products for Ageing and Chronic Diseases,
Chulalongkorn University, Bangkok, Thailand
- Department of Food and Pharmaceutical Chemistry, Faculty of
Pharmaceutical Sciences, Chulalongkorn University, Bangkok,
Thailand
| | - Pasarapa Towiwat
- Center of Excellence in Natural Products for Ageing and Chronic Diseases,
Chulalongkorn University, Bangkok, Thailand
- Department of Pharmacology and Physiology, Faculty of Pharmaceutical
Sciences, Chulalongkorn University, Bangkok, Thailand
| | - Opa Vajragupta
- Center of Excellence in Natural Products for Ageing and Chronic Diseases,
Chulalongkorn University, Bangkok, Thailand
- Research Affairs, Faculty of Pharmaceutical Sciences, Chulalongkorn
University, Bangkok, Thailand
| | - Pornchai Rojsitthisak
- Center of Excellence in Natural Products for Ageing and Chronic Diseases,
Chulalongkorn University, Bangkok, Thailand
- Department of Food and Pharmaceutical Chemistry, Faculty of
Pharmaceutical Sciences, Chulalongkorn University, Bangkok,
Thailand
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Bukina ES, Kondratyev NV, Kozin SV, Golimbet VE, Artyuhov AS, Dashinimaev EB. SLC6A1 and Neuropsychiatric Diseases: The Role of Mutations and Prospects for Treatment with Genome Editing Systems. NEUROCHEM J+ 2021. [DOI: 10.1134/s1819712421040048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Panthi S, Lyons NMA, Leitch B. Impact of Dysfunctional Feed-Forward Inhibition on Glutamate Decarboxylase Isoforms and γ-Aminobutyric Acid Transporters. Int J Mol Sci 2021; 22:ijms22147740. [PMID: 34299369 PMCID: PMC8306481 DOI: 10.3390/ijms22147740] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 07/16/2021] [Indexed: 12/02/2022] Open
Abstract
Absence seizures are associated with generalised synchronous 2.5–4 Hz spike-wave discharges causing brief and sudden alteration of awareness during childhood, which is known as childhood absence epilepsy (CAE). CAE is also associated with impaired learning, psychosocial challenges, and physical danger. Absence seizures arise from disturbances within the cortico-thalamocortical (CTC) network, including dysfunctional feed-forward inhibition (FFI); however, the precise mechanisms remain unclear. In epileptic stargazers, a genetic mouse model of CAE with chronic seizures, levels of γ-aminobutyric acid (GABA), and expression of GABA receptors are altered within the CTC network, implicating altered GABAergic transmission in absence seizures. However, the expression of GABA synthesising enzymes (GAD65 and GAD67) and GABA transporters (GAT-1 and 3) have not yet been characterised within absence seizure models. We found a specific upregulation of GAD65 in the somatosensory cortex but not the thalamus of epileptic stargazer mice. No differences were detected in GAD67 and GAT-3 levels in the thalamus or somatosensory cortex. Then, we assessed if GAD65 upregulation also occurred in Gi-DREADD mice exhibiting acute absence seizures, but we found no change in the expression profiles of GAD65/67 or GAT-3. Thus, the upregulation of GAD65 in stargazers may be a compensatory mechanism in response to long-term dysfunctional FFI and chronic absence seizures.
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Affiliation(s)
| | | | - Beulah Leitch
- Correspondence: ; Tel.: +64-3-479-7618; Fax: +64-3-479-7254
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Goodspeed K, Pérez-Palma E, Iqbal S, Cooper D, Scimemi A, Johannesen KM, Stefanski A, Demarest S, Helbig KL, Kang J, Shaffo FC, Prentice B, Brownstein CA, Lim B, Helbig I, De Los Reyes E, McKnight D, Crunelli V, Campbell AJ, Møller RS, Freed A, Lal D. Current knowledge of SLC6A1-related neurodevelopmental disorders. Brain Commun 2020; 2:fcaa170. [PMID: 33241211 PMCID: PMC7677605 DOI: 10.1093/braincomms/fcaa170] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 09/09/2020] [Accepted: 09/14/2020] [Indexed: 12/18/2022] Open
Abstract
Advances in gene discovery have identified genetic variants in the solute carrier family 6 member 1 gene as a monogenic cause of neurodevelopmental disorders, including epilepsy with myoclonic atonic seizures, autism spectrum disorder and intellectual disability. The solute carrier family 6 member 1 gene encodes for the GABA transporter protein type 1, which is responsible for the reuptake of the neurotransmitter GABA, the primary inhibitory neurotransmitter in the central nervous system, from the extracellular space. GABAergic inhibition is essential to counterbalance neuronal excitation, and when significantly disrupted, it negatively impacts brain development leading to developmental differences and seizures. Aggregation of patient variants and observed clinical manifestations expand understanding of the genotypic and phenotypic spectrum of this disorder. Here, we assess genetic and phenotypic features in 116 individuals with solute carrier family 6 member 1 variants, the vast majority of which are likely to lead to GABA transporter protein type 1 loss-of-function. The knowledge acquired will guide therapeutic decisions and the development of targeted therapies that selectively enhance transporter function and may improve symptoms. We analysed the longitudinal and cell type-specific expression of solute carrier family 6 member 1 in humans and localization of patient and control missense variants in a novel GABA transporter protein type 1 protein structure model. In this update, we discuss the progress made in understanding and treating solute carrier family 6 member 1-related disorders thus far, through the concerted efforts of clinicians, scientists and family support groups.
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Affiliation(s)
- Kimberly Goodspeed
- Children's Health, Medical Center, UT Southwestern, Dallas, TX 75235, USA
- Department of Pediatrics, Medical Center, UT Southwestern, Dallas, TX 75235, USA
| | - Eduardo Pérez-Palma
- Genomic Medicine Institute, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44195, USA
| | - Sumaiya Iqbal
- Broad Institute of MIT and Harvard, Stanley Center for Psychiatric Research, Cambridge, MA 02142, USA
- Broad Institute of MIT and Harvard, Center for Development of Therapeutics, Cambridge, MA 02142, USA
| | - Dominique Cooper
- Children's Health, Medical Center, UT Southwestern, Dallas, TX 75235, USA
| | - Annalisa Scimemi
- Department of Biological Sciences, University at Albany, Albany, NY 12222, USA
| | - Katrine M Johannesen
- Department of Epilepsy Genetics and Personalized Treatment, Danish Epilepsy Center Filadelfia, Dianalund 4293, Denmark
- Department of Regional Health Research, Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Arthur Stefanski
- Genomic Medicine Institute, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44195, USA
| | - Scott Demarest
- Departments of Pediatrics and Neurology, University of Colorado School of Medicine, Aurora, CO, USA
- Department of Pediatric Neurology and Neuroscience Institute, Children's Hospital Colorado, Aurora, CO, USA
| | - Katherine L Helbig
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
- The Epilepsy NeuroGenetics Initiative (ENGIN), Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Department of Biomedical and Health Informatics (DBHi), Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Jingqiong Kang
- Department of Neurology, Vanderbilt University Medical Center, TN 37232, USA
| | - Frances C Shaffo
- Department of Pediatrics, Medical Center, UT Southwestern, Dallas, TX 75235, USA
| | | | - Catherine A Brownstein
- Division of Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Byungchan Lim
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Hospital, Seoul 03080, Republic of Korea
| | - Ingo Helbig
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
- The Epilepsy NeuroGenetics Initiative (ENGIN), Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Department of Biomedical and Health Informatics (DBHi), Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Emily De Los Reyes
- Department of Pediatric Neurology, Nationwide Children's Hospital, Columbus, OH, USA
- The Ohio State University College of Medicine, Columbus, OH, USA
| | | | - Vincenzo Crunelli
- Neuroscience Division, School of Bioscience, Cardiff University, Cardiff, UK
- Faculty of Medicine and Surgery, Malta University, Msida, Malta
| | - Arthur J Campbell
- Broad Institute of MIT and Harvard, Stanley Center for Psychiatric Research, Cambridge, MA 02142, USA
- Broad Institute of MIT and Harvard, Center for Development of Therapeutics, Cambridge, MA 02142, USA
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Treatment, Danish Epilepsy Center Filadelfia, Dianalund 4293, Denmark
- Department of Regional Health Research, Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Amber Freed
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Dennis Lal
- Genomic Medicine Institute, Lerner Research Institute Cleveland Clinic, Cleveland, OH 44195, USA
- Broad Institute of MIT and Harvard, Stanley Center for Psychiatric Research, Cambridge, MA 02142, USA
- Neurological Institute, Epilepsy Center, Cleveland Clinic, Cleveland, OH 44195, USA
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Fattorini G, Melone M, Conti F. A Reappraisal of GAT-1 Localization in Neocortex. Front Cell Neurosci 2020; 14:9. [PMID: 32116556 PMCID: PMC7031676 DOI: 10.3389/fncel.2020.00009] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 01/13/2020] [Indexed: 12/31/2022] Open
Abstract
γ-Aminobutyric acid (GABA) transporter (GAT)-1, the major GABA transporter in the brain, plays a key role in modulating GABA signaling and is involved in the pathophysiology of several neuropsychiatric diseases, including epilepsy. The original description of GAT-1 as a neuronal transporter has guided the interpretation of the findings of all physiological, pharmacological, genetic, or clinical studies. However, evidence published in the past few years, some of which is briefly reviewed herein, does not seem to be consistent with a neurocentric view of GAT-1 function and calls for more detailed analysis of its localization. We therefore performed a thorough systematic assessment of GAT-1 localization in neocortex and subcortical white matter. In line with earlier work, we found that GAT-1 was robustly expressed in axon terminals forming symmetric synapses and in astrocytic processes, whereas its astrocytic expression was more diffuse than expected and, even more surprisingly, immature and mature oligodendrocytes and microglial cells also expressed the transporter. These data indicate that the era of “neuronal” and “glial” GABA transporters has finally come to a close and provide a wider perspective from which to view GABA-mediated physiological phenomena. In addition, given the well-known involvement of astrocytes, oligodendrocytes, and microglial cells in physiological as well as pathological conditions, the demonstration of functional GAT-1 in these cells is expected to provide greater insight into the phenomena occurring in the diseased brain as well as to prompt a reassessment of earlier findings.
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Affiliation(s)
- Giorgia Fattorini
- Department of Experimental and Clinical Medicine, Faculty of Medicine and Surgery, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy
| | - Marcello Melone
- Department of Experimental and Clinical Medicine, Faculty of Medicine and Surgery, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy
| | - Fiorenzo Conti
- Department of Experimental and Clinical Medicine, Faculty of Medicine and Surgery, Università Politecnica delle Marche, Ancona, Italy.,Center for Neurobiology of Aging, IRCCS INRCA, Ancona, Italy.,Fondazione di Medicina Molecolare, Università Politecnica delle Marche, Ancona, Italy
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