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Kerdiles O, Oye Mintsa Mi-Mba MF, Coulombe K, Tremblay C, Émond V, Saint-Pierre M, Rouxel C, Berthiaume L, Julien P, Cicchetti F, Calon F. Additive neurorestorative effects of exercise and docosahexaenoic acid intake in a mouse model of Parkinson's disease. Neural Regen Res 2025; 20:574-586. [PMID: 38819068 DOI: 10.4103/nrr.nrr-d-23-00595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 01/30/2024] [Indexed: 06/01/2024] Open
Abstract
JOURNAL/nrgr/04.03/01300535-202502000-00033/figure1/v/2024-05-28T214302Z/r/image-tiff There is a need to develop interventions to slow or reverse the degeneration of dopamine neurons in Parkinson's disease after diagnosis. Given that preclinical and clinical studies suggest benefits of dietary n-3 polyunsaturated fatty acids, such as docosahexaenoic acid, and exercise in Parkinson's disease, we investigated whether both could synergistically interact to induce recovery of the dopaminergic pathway. First, mice received a unilateral stereotactic injection of 6-hydroxydopamine into the striatum to establish an animal model of nigrostriatal denervation. Four weeks after lesion, animals were fed a docosahexaenoic acid-enriched or a control diet for the next 8 weeks. During this period, the animals had access to a running wheel, which they could use or not. Docosahexaenoic acid treatment, voluntary exercise, or the combination of both had no effect on (i) distance traveled in the open field test, (ii) the percentage of contraversive rotations in the apomorphine-induction test or (iii) the number of tyrosine-hydroxylase-positive cells in the substantia nigra pars compacta. However, the docosahexaenoic acid diet increased the number of tyrosine-hydroxylase-positive terminals and induced a rise in dopamine concentrations in the lesioned striatum. Compared to docosahexaenoic acid treatment or exercise alone, the combination of docosahexaenoic acid and exercise (i) improved forelimb balance in the stepping test, (ii) decreased the striatal DOPAC/dopamine ratio and (iii) led to increased dopamine transporter levels in the lesioned striatum. The present results suggest that the combination of exercise and docosahexaenoic acid may act synergistically in the striatum of mice with a unilateral lesion of the dopaminergic system and provide support for clinical trials combining nutrition and physical exercise in the treatment of Parkinson's disease.
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Affiliation(s)
- Olivier Kerdiles
- Faculté de pharmacie, Université Laval, 1050 Avenue de la Médecine, Quebec, QC, Canada
- Axe Neuroscience, Centre de recherche du CHU de Québec-Université Laval (Pavillon CHUL), 2705 Boulevard Laurier, Quebec, QC, Canada
- Institute of Nutrition and Functional Foods, Quebec, QC, Canada
- Optinutribrain International Associated Laboratory (NutriNeuro, France; INAF, Canada), Quebec, QC, Canada
| | - Méryl-Farelle Oye Mintsa Mi-Mba
- Faculté de pharmacie, Université Laval, 1050 Avenue de la Médecine, Quebec, QC, Canada
- Axe Neuroscience, Centre de recherche du CHU de Québec-Université Laval (Pavillon CHUL), 2705 Boulevard Laurier, Quebec, QC, Canada
- Institute of Nutrition and Functional Foods, Quebec, QC, Canada
- Optinutribrain International Associated Laboratory (NutriNeuro, France; INAF, Canada), Quebec, QC, Canada
| | - Katherine Coulombe
- Axe Neuroscience, Centre de recherche du CHU de Québec-Université Laval (Pavillon CHUL), 2705 Boulevard Laurier, Quebec, QC, Canada
| | - Cyntia Tremblay
- Axe Neuroscience, Centre de recherche du CHU de Québec-Université Laval (Pavillon CHUL), 2705 Boulevard Laurier, Quebec, QC, Canada
- Optinutribrain International Associated Laboratory (NutriNeuro, France; INAF, Canada), Quebec, QC, Canada
| | - Vincent Émond
- Axe Neuroscience, Centre de recherche du CHU de Québec-Université Laval (Pavillon CHUL), 2705 Boulevard Laurier, Quebec, QC, Canada
- Optinutribrain International Associated Laboratory (NutriNeuro, France; INAF, Canada), Quebec, QC, Canada
| | - Martine Saint-Pierre
- Axe Neuroscience, Centre de recherche du CHU de Québec-Université Laval (Pavillon CHUL), 2705 Boulevard Laurier, Quebec, QC, Canada
| | - Clémence Rouxel
- Axe Neuroscience, Centre de recherche du CHU de Québec-Université Laval (Pavillon CHUL), 2705 Boulevard Laurier, Quebec, QC, Canada
- Institute of Nutrition and Functional Foods, Quebec, QC, Canada
| | - Line Berthiaume
- Axe Endocrinologie et Néphrologie, Centre de recherche du CHU de Québec-Université Laval, Quebec, QC, Canada
- Département de Médecine, Faculté de Médecine, Université Laval, Quebec, QC, Canada
| | - Pierre Julien
- Axe Endocrinologie et Néphrologie, Centre de recherche du CHU de Québec-Université Laval, Quebec, QC, Canada
- Département de Médecine, Faculté de Médecine, Université Laval, Quebec, QC, Canada
| | - Francesca Cicchetti
- Axe Neuroscience, Centre de recherche du CHU de Québec-Université Laval (Pavillon CHUL), 2705 Boulevard Laurier, Quebec, QC, Canada
- Département de Psychiatrie et Neurosciences, Faculté de Médecine, Quebec, QC, Canada
| | - Frédéric Calon
- Faculté de pharmacie, Université Laval, 1050 Avenue de la Médecine, Quebec, QC, Canada
- Axe Neuroscience, Centre de recherche du CHU de Québec-Université Laval (Pavillon CHUL), 2705 Boulevard Laurier, Quebec, QC, Canada
- Institute of Nutrition and Functional Foods, Quebec, QC, Canada
- Optinutribrain International Associated Laboratory (NutriNeuro, France; INAF, Canada), Quebec, QC, Canada
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El-Kasaby A, Boytsov D, Kasture A, Krumpl G, Hummel T, Freissmuth M, Sandtner W. Allosteric Inhibition and Pharmacochaperoning of the Serotonin Transporter by the Antidepressant Drugs Trazodone and Nefazodone. Mol Pharmacol 2024; 106:56-70. [PMID: 38769018 DOI: 10.1124/molpharm.124.000881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 05/06/2024] [Accepted: 05/07/2024] [Indexed: 05/22/2024] Open
Abstract
The antidepressants trazodone and nefazodone were approved some 4 and 3 decades ago, respectively. Their action is thought to be mediated, at least in part, by inhibition of the serotonin transporter [SERT/solute carrier (SLC)-6A4]. Surprisingly, their mode of action on SERT has not been characterized. Here, we show that, similar to the chemically related drug vilazodone, trazodone and nefazodone are allosteric ligands: trazodone and nefazodone inhibit uptake by and transport-associated currents through SERT in a mixed-competitive and noncompetitive manner, respectively. Contrary to noribogaine and its congeners, all three compounds preferentially interact with the Na+-bound outward-facing state of SERT. Nevertheless, they act as pharmacochaperones and rescue the folding-deficient variant SERT-P601A/G602A. The vast majority of disease-associated point mutations of SLC6 family members impair folding of the encoded transporter proteins. Our findings indicate that their folding defect can be remedied by targeting allosteric sites on SLC6 transporters. SIGNIFICANCE STATEMENT: The serotonin transporter is a member of the solute carrier-6 family and is the target of numerous antidepressants. Trazodone and nefazodone have long been used as antidepressants. Here, this study shows that their inhibition of the serotonin transporter digressed from the competitive mode seen with other antidepressants. Trazodone and nefazodone rescued a folding-deficient variant of the serotonin transporter. This finding demonstrates that folding defects of mutated solute carrier-6 family members can also be corrected by allosteric ligands.
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Affiliation(s)
- Ali El-Kasaby
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology (A.E.-K., D.B., M.F., W.S.), Medical University of Vienna, Vienna, Austria; Department of Neurobiology, University of Vienna, Vienna, Austria (A.K., T.H.); and MRN Medical Research Network GmbH, Vienna, Austria (G.K.)
| | - Danila Boytsov
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology (A.E.-K., D.B., M.F., W.S.), Medical University of Vienna, Vienna, Austria; Department of Neurobiology, University of Vienna, Vienna, Austria (A.K., T.H.); and MRN Medical Research Network GmbH, Vienna, Austria (G.K.)
| | - Ameya Kasture
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology (A.E.-K., D.B., M.F., W.S.), Medical University of Vienna, Vienna, Austria; Department of Neurobiology, University of Vienna, Vienna, Austria (A.K., T.H.); and MRN Medical Research Network GmbH, Vienna, Austria (G.K.)
| | - Günther Krumpl
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology (A.E.-K., D.B., M.F., W.S.), Medical University of Vienna, Vienna, Austria; Department of Neurobiology, University of Vienna, Vienna, Austria (A.K., T.H.); and MRN Medical Research Network GmbH, Vienna, Austria (G.K.)
| | - Thomas Hummel
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology (A.E.-K., D.B., M.F., W.S.), Medical University of Vienna, Vienna, Austria; Department of Neurobiology, University of Vienna, Vienna, Austria (A.K., T.H.); and MRN Medical Research Network GmbH, Vienna, Austria (G.K.)
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology (A.E.-K., D.B., M.F., W.S.), Medical University of Vienna, Vienna, Austria; Department of Neurobiology, University of Vienna, Vienna, Austria (A.K., T.H.); and MRN Medical Research Network GmbH, Vienna, Austria (G.K.)
| | - Walter Sandtner
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Centre of Physiology and Pharmacology (A.E.-K., D.B., M.F., W.S.), Medical University of Vienna, Vienna, Austria; Department of Neurobiology, University of Vienna, Vienna, Austria (A.K., T.H.); and MRN Medical Research Network GmbH, Vienna, Austria (G.K.)
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Mayer FP, Stewart A, Varman DR, Moritz AE, Foster JD, Owens AW, Areal LB, Gowrishankar R, Velez M, Wickham K, Phelps H, Katamish R, Rabil M, Jayanthi LD, Vaughan RA, Daws LC, Blakely RD, Ramamoorthy S. Kappa Opioid Receptor Antagonism Restores Phosphorylation, Trafficking and Behavior induced by a Disease Associated Dopamine Transporter Variant. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.03.539310. [PMID: 37205452 PMCID: PMC10187322 DOI: 10.1101/2023.05.03.539310] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Aberrant dopamine (DA) signaling is implicated in schizophrenia, bipolar disorder (BPD), autism spectrum disorder (ASD), substance use disorder, and attention-deficit/hyperactivity disorder (ADHD). Treatment of these disorders remains inadequate, as exemplified by the therapeutic use of d-amphetamine and methylphenidate for the treatment of ADHD, agents with high abuse liability. In search for an improved and non-addictive therapeutic approach for the treatment of DA-linked disorders, we utilized a preclinical mouse model expressing the human DA transporter (DAT) coding variant DAT Val559, previously identified in individuals with ADHD, ASD, or BPD. DAT Val559, like several other disease-associated variants of DAT, exhibits anomalous DA efflux (ADE) that can be blocked by d-amphetamine and methylphenidate. Kappa opioid receptors (KORs) are expressed by DA neurons and modulate DA release and clearance, suggesting that targeting KORs might also provide an alternative approach to normalizing DA-signaling disrupted by perturbed DAT function. Here we demonstrate that KOR stimulation leads to enhanced surface trafficking and phosphorylation of Thr53 in wildtype DAT, effects achieved constitutively by the Val559 mutant. Moreover, these effects can be rescued by KOR antagonism of DAT Val559 in ex vivo preparations. Importantly, KOR antagonism also corrected in vivo DA release as well as sex-dependent behavioral abnormalities observed in DAT Val559 mice. Given their low abuse liability, our studies with a construct valid model of human DA associated disorders reinforce considerations of KOR antagonism as a pharmacological strategy to treat DA associated brain disorders.
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Affiliation(s)
- Felix P. Mayer
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL, USA
| | - Adele Stewart
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL, USA
| | - Durairaj Ragu Varman
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Amy E. Moritz
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - James D. Foster
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Anthony W. Owens
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, TX, USA
| | - Lorena B. Areal
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Raajaram Gowrishankar
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Michelle Velez
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Kyria Wickham
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Hannah Phelps
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Rania Katamish
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Maximilian Rabil
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
| | - Lankupalle D. Jayanthi
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Roxanne A. Vaughan
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND, USA
| | - Lynette C. Daws
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, TX, USA
- Department of Pharmacology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Randy D. Blakely
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, Jupiter, FL, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL, USA
| | - Sammanda Ramamoorthy
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
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Liao K, Xiang Y, Huang F, Huang M, Xu W, Lin Y, Liao P, Wang Z, Yang L, Tian X, Chen D, Wang Z, Liu S, Zhuang Z. Spatial and single-nucleus transcriptomics decoding the molecular landscape and cellular organization of avian optic tectum. iScience 2024; 27:109009. [PMID: 38333704 PMCID: PMC10850779 DOI: 10.1016/j.isci.2024.109009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 12/19/2023] [Accepted: 01/22/2024] [Indexed: 02/10/2024] Open
Abstract
The avian optic tectum (OT) has been studied for its diverse functions, yet a comprehensive molecular landscape at the cellular level has been lacking. In this study, we applied spatial transcriptome sequencing and single-nucleus RNA sequencing (snRNA-seq) to explore the cellular organization and molecular characteristics of the avian OT from two species: Columba livia and Taeniopygia guttata. We identified precise layer structures and provided comprehensive layer-specific signatures of avian OT. Furthermore, we elucidated diverse functions in different layers, with the stratum griseum periventriculare (SGP) potentially playing a key role in advanced functions of OT, like fear response and associative learning. We characterized detailed neuronal subtypes and identified a population of FOXG1+ excitatory neurons, resembling those found in the mouse neocortex, potentially involved in neocortex-related functions and expansion of avian OT. These findings could contribute to our understanding of the architecture of OT, shedding light on visual perception and multifunctional association.
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Affiliation(s)
- Kuo Liao
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
- BGI Research, Hangzhou 310030, China
| | - Ya Xiang
- BGI Research, Hangzhou 310030, China
- College of Life Sciences, Northwest University, Xi’an 710069, China
| | - Fubaoqian Huang
- School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China
- BGI Research, Hangzhou 310030, China
| | - Maolin Huang
- School of Life Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Wenbo Xu
- School of Life Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Youning Lin
- BGI Research, Hangzhou 310030, China
- BGI Research, Shenzhen 518083, China
| | - Pingfang Liao
- BGI Research, Hangzhou 310030, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zishi Wang
- School of Life Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Lin Yang
- School of Life Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Xinmao Tian
- School of Life Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Duoyuan Chen
- BGI Research, Hangzhou 310030, China
- BGI Research, Shenzhen 518083, China
| | - Zhenlong Wang
- School of Life Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Shiping Liu
- BGI Research, Hangzhou 310030, China
- BGI Research, Shenzhen 518083, China
| | - Zhenkun Zhuang
- BGI Research, Hangzhou 310030, China
- BGI Research, Shenzhen 518083, China
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Mayer FP, Stewart A, Blakely RD. Leaky lessons learned: Efflux prone dopamine transporter variant reveals sex and circuit specific contributions of D2 receptor signalling to neuropsychiatric disease. Basic Clin Pharmacol Toxicol 2024; 134:206-218. [PMID: 37987120 DOI: 10.1111/bcpt.13964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 11/14/2023] [Accepted: 11/17/2023] [Indexed: 11/22/2023]
Abstract
Aberrant dopamine (DA) signalling has been implicated in various neuropsychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), schizophrenia, bipolar disorder (BPD) and addiction. The availability of extracellular DA is sculpted by the exocytotic release of vesicular DA and subsequent transporter-mediated clearance, rendering the presynaptic DA transporter (DAT) a crucial regulator of DA neurotransmission. D2-type DA autoreceptors (D2ARs) regulate multiple aspects of DA homeostasis, including (i) DA synthesis, (ii) vesicular release, (iii) DA neuron firing and (iv) the surface expression of DAT and DAT-mediated DA clearance. The DAT Val559 variant, identified in boys with ADHD or ASD, as well as in a girl with BPD, supports anomalous DA efflux (ADE), which we have shown drives tonic activation of D2ARs. Through ex vivo and in vivo studies of the DAT Val559 variant using transgenic knock-in mice, we have uncovered a circuit and sex-specific capacity of D2ARs to regulate DAT, which consequently disrupts DA signalling and behaviour differently in males and females. Our studies reveal the ability of the construct-valid DAT Val559 model to elucidate endogenous mechanisms that support DA signalling, findings that may be of translational and/or therapeutic importance.
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Affiliation(s)
- Felix P Mayer
- Department of Biomedical Science, Florida Atlantic University, Jupiter, Florida, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida, USA
| | - Adele Stewart
- Department of Biomedical Science, Florida Atlantic University, Jupiter, Florida, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida, USA
| | - Randy D Blakely
- Department of Biomedical Science, Florida Atlantic University, Jupiter, Florida, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida, USA
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Støier JF, Jørgensen TN, Sparsø T, Rasmussen HB, Kumar V, Newman AH, Blakely RD, Werge T, Gether U, Herborg F. Disruptive mutations in the serotonin transporter associate serotonin dysfunction with treatment-resistant affective disorder. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.08.29.23294386. [PMID: 37693601 PMCID: PMC10491376 DOI: 10.1101/2023.08.29.23294386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Affective or mood disorders are a leading cause of disability worldwide. The serotonergic system has been heavily implicated in the complex etiology and serves as a therapeutic target. The serotonin transporter (SERT) is a major regulator of serotonin neurotransmission, yet the disease-relevance of impaired SERT function remains unknown. Here, we present the first identification and functional characterization of disruptive coding SERT variants found in patients with psychiatric diseases. In a unique cohort of 144 patients characterized by treatment-resistant chronic affective disorders with a lifetime history of electroconvulsive therapy, we identified two previously uncharacterized coding SERT variants: SERT-N217S and SERT-A500T. Both variants were significantly enriched in the patient cohort compared to GnomAD (SERT-N217S: OR = 151, P = 0.0001 and SERT-A500T: OR = 1348, P = 0.0022) and ethnicity-matched healthy controls (SERT-N217S: OR ≥ 17.7, P ≤ 0.013 and SERT-A500T: OR = ∞, P = 0.029). Functional investigations revealed that the mutations exert distinct perturbations to SERT function, but their overall effects converge on a partial loss-of-function molecular phenotype. Thus, the SERT-A500T variant compromises the catalytic activity, while SERT-N217S disrupts proper glycosylation of SERT with a resulting dominant-negative trafficking deficiency. Moreover, we demonstrate that the trafficking deficiency of SERT-N217S is amenable to pharmacochaperoning by noribogaine. Collectively, our findings describe the first disease-associated loss-of-function SERT variants and implicate serotonergic disturbances arising from SERT dysfunction as a risk factor for chronic affective disorders.
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Weishaupt AK, Kubens L, Ruecker L, Schwerdtle T, Aschner M, Bornhorst J. A Reliable Method Based on Liquid Chromatography-Tandem Mass Spectrometry for the Simultaneous Quantification of Neurotransmitters in Caenorhabditis elegans. Molecules 2023; 28:5373. [PMID: 37513246 PMCID: PMC10385323 DOI: 10.3390/molecules28145373] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/05/2023] [Accepted: 07/10/2023] [Indexed: 07/30/2023] Open
Abstract
Neurotransmitters like dopamine (DA), serotonin (SRT), γ-aminobutyric acid (GABA) and acetylcholine (ACh) are messenger molecules that play a pivotal role in transmitting excitation between neurons across chemical synapses, thus enabling complex processes in the central nervous system (CNS). Balance in neurotransmitter homeostasis is essential, and altered neurotransmitter levels are associated with various neurological disorders, e.g., loss of dopaminergic neurons (Parkinson's disease) or altered ACh synthesis (Alzheimer's disease). Therefore, it is crucial to possess adequate tools to assess precise neurotransmitter levels, and to apply targeted therapies. An established in vivo model to study neurotoxicity is the model organism Caenorhabditis elegans (C. elegans), as its neurons have been well characterized and functionally are analogous to mammals. We have developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method including a sample preparation assuring neurotransmitter stability, which allows a simultaneous neurotransmitter quantification of DA, SRT, GABA and ACh in C. elegans, but can easily be applied to other matrices. LC-MS/MS combined with isotope-labeled standards is the tool of choice, due to its otherwise unattainable sensitivity and specificity. Using C. elegans together with our analytically validated and verified method provides a powerful tool to evaluate mechanisms of neurotoxicity, and furthermore to identify possible therapeutic approaches.
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Affiliation(s)
- Ann-Kathrin Weishaupt
- Food Chemistry, Faculty of Mathematics and Natural Sciences, University of Wuppertal, Gaußstraße 20, 42119 Wuppertal, Germany; (A.-K.W.); (L.K.); (L.R.)
- TraceAge—DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly (FOR 2558), Berlin-Potsdam-Jena-Wuppertal, 14558 Nuthetal, Germany;
| | - Laura Kubens
- Food Chemistry, Faculty of Mathematics and Natural Sciences, University of Wuppertal, Gaußstraße 20, 42119 Wuppertal, Germany; (A.-K.W.); (L.K.); (L.R.)
- Inorganic Chemistry, Faculty of Mathematics and Natural Sciences, University of Wuppertal, Gaußstraße 20, 42119 Wuppertal, Germany
| | - Lysann Ruecker
- Food Chemistry, Faculty of Mathematics and Natural Sciences, University of Wuppertal, Gaußstraße 20, 42119 Wuppertal, Germany; (A.-K.W.); (L.K.); (L.R.)
| | - Tanja Schwerdtle
- TraceAge—DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly (FOR 2558), Berlin-Potsdam-Jena-Wuppertal, 14558 Nuthetal, Germany;
- German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Straße 8-10, 10589 Berlin, Germany
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10032, USA;
| | - Julia Bornhorst
- Food Chemistry, Faculty of Mathematics and Natural Sciences, University of Wuppertal, Gaußstraße 20, 42119 Wuppertal, Germany; (A.-K.W.); (L.K.); (L.R.)
- TraceAge—DFG Research Unit on Interactions of Essential Trace Elements in Healthy and Diseased Elderly (FOR 2558), Berlin-Potsdam-Jena-Wuppertal, 14558 Nuthetal, Germany;
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Dvorak V, Superti-Furga G. Structural and functional annotation of solute carrier transporters: implication for drug discovery. Expert Opin Drug Discov 2023; 18:1099-1115. [PMID: 37563933 DOI: 10.1080/17460441.2023.2244760] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/01/2023] [Indexed: 08/12/2023]
Abstract
INTRODUCTION Solute carriers (SLCs) represent the largest group of membrane transporters in the human genome. They play a central role in controlling the compartmentalization of metabolism and most of this superfamily is linked to human disease. Despite being in general considered druggable and attractive therapeutic targets, many SLCs remain poorly annotated, both functionally and structurally. AREAS COVERED The aim of this review is to provide an overview of functional and structural parameters of SLCs that play important roles in their druggability. To do this, the authors provide an overview of experimentally solved structures of human SLCs, with emphasis on structures solved in complex with chemical modulators. From the functional annotations, the authors focus on SLC localization and SLC substrate annotations. EXPERT OPINION Recent progress in the structural and functional annotations allows to refine the SLC druggability index. Particularly the increasing number of experimentally solved structures of SLCs provides insights into mode-of-action of a significant number of chemical modulators of SLCs.
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Affiliation(s)
- Vojtech Dvorak
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Giulio Superti-Furga
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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Boytsov D, Schicker K, Hellsberg E, Freissmuth M, Sandtner W. Allosteric modulators of solute carrier function: a theoretical framework. Front Physiol 2023; 14:1166450. [PMID: 37250134 PMCID: PMC10210158 DOI: 10.3389/fphys.2023.1166450] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 04/24/2023] [Indexed: 05/31/2023] Open
Abstract
Large-scale drug screening is currently the basis for the identification of new chemical entities. This is a rather laborious approach, because a large number of compounds must be tested to cover the chemical space in an unbiased fashion. However, the structures of targetable proteins have become increasingly available. Thus, a new era has arguably been ushered in with the advent of methods, which allow for structure-based docking campaigns (i.e., virtual screens). Solute carriers (SLCs) are among the most promising drug targets. This claim is substantiated by the fact that a large fraction of the 400 solute carrier genes is associated with human diseases. The ability to dock large ligand libraries into selected structures of solute carriers has set the stage for rational drug design. In the present study, we show that these structure-based approaches can be refined by taking into account how solute carriers operate. We specifically address the feasibility of targeting solute carriers with allosteric modulators, because their actions differ fundamentally from those of ligands, which bind to the substrate binding site. For the pertinent analysis we used transition state theory in conjunction with the linear free energy relationship (LFER). These provide the theoretical framework to understand how allosteric modulators affect solute carrier function.
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Affiliation(s)
- D. Boytsov
- Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - K. Schicker
- Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - E. Hellsberg
- Computational Structural Biology Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, MD, United States
| | - M. Freissmuth
- Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - W. Sandtner
- Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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10
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Niello M, Sideromenos S, Gradisch R, O´Shea R, Schwazer J, Maier J, Kastner N, Sandtner W, Jäntsch K, Lupica CR, Hoffman AF, Lubec G, Loland CJ, Stockner T, Pollak DD, Baumann MH, Sitte HH. Persistent binding at dopamine transporters determines sustained psychostimulant effects. Proc Natl Acad Sci U S A 2023; 120:e2114204120. [PMID: 36730201 PMCID: PMC9963675 DOI: 10.1073/pnas.2114204120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 12/28/2022] [Indexed: 02/03/2023] Open
Abstract
Psychostimulants interacting with the dopamine transporter (DAT) can be used illicitly or for the treatment of specific neuropsychiatric disorders. However, they can also produce severe and persistent adverse events. Often, their pharmacological properties in vitro do not fully correlate to their pharmacological profile in vivo. Here, we investigated the pharmacological effects of enantiomers of pyrovalerone, α-pyrrolidinovalerophenone, and 3,4-methylenedioxypyrovalerone as compared to the traditional psychostimulants cocaine and methylphenidate, using a variety of in vitro, computational, and in vivo approaches. We found that in vitro drug-binding kinetics at DAT correlate with the time-course of in vivo psychostimulant action in mice. In particular, a slow dissociation (i.e., slow koff) of S-enantiomers of pyrovalerone analogs from DAT predicts their more persistent in vivo effects when compared to cocaine and methylphenidate. Overall, our findings highlight the critical importance of drug-binding kinetics at DAT for determining the in vivo profile of effects produced by psychostimulant drugs.
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Affiliation(s)
- Marco Niello
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Spyridon Sideromenos
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Ralph Gradisch
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Ronan O´Shea
- Electrophysiology Research Section, National Institute on Drug Abuse, NIH, Baltimore, MD21224
| | - Jakob Schwazer
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Julian Maier
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Nina Kastner
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Walter Sandtner
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Kathrin Jäntsch
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Carl R. Lupica
- Electrophysiology Research Section, National Institute on Drug Abuse, NIH, Baltimore, MD21224
| | - Alexander F. Hoffman
- Electrophysiology Research Section, National Institute on Drug Abuse, NIH, Baltimore, MD21224
| | - Gert Lubec
- Department of Neuroproteomics, Paracelsus Medical University, 5020Salzburg, Austria
| | - Claus J. Loland
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200Copenhagen, Denmark
| | - Thomas Stockner
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Daniela D. Pollak
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Michael H. Baumann
- Designer Drug Research Unit, Intramural Research Program, National Institute on Drug Abuse, NIH, Baltimore, MD21224
| | - Harald H. Sitte
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
- AddRess, Center for Addiction Research and Science, Medical University of Vienna, 1090Vienna, Austria
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11
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Kasture AS, Fischer FP, Kunert L, Burger ML, Burgstaller AC, El-Kasaby A, Hummel T, Sucic S. Drosophila melanogaster as a model for unraveling unique molecular features of epilepsy elicited by human GABA transporter 1 variants. Front Neurosci 2023; 16:1074427. [PMID: 36741049 PMCID: PMC9893286 DOI: 10.3389/fnins.2022.1074427] [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: 10/19/2022] [Accepted: 12/21/2022] [Indexed: 01/20/2023] Open
Abstract
Mutations in the human γ-aminobutyric acid (GABA) transporter 1 (hGAT-1) can instigate myoclonic-atonic and other generalized epilepsies in the afflicted individuals. We systematically examined fifteen hGAT-1 disease variants, all of which dramatically reduced or completely abolished GABA uptake activity. Many of these loss-of-function variants were absent from their regular site of action at the cell surface, due to protein misfolding and/or impaired trafficking machinery (as verified by confocal microscopy and de-glycosylation experiments). A modest fraction of the mutants displayed correct targeting to the plasma membrane, but nonetheless rendered the mutated proteins devoid of GABA transport, possibly due to structural alterations in the GABA binding site/translocation pathway. We here focused on a folding-deficient A288V variant. In flies, A288V reiterated its impeded expression pattern, closely mimicking the ER-retention demonstrated in transfected HEK293 cells. Functionally, A288V presented a temperature-sensitive seizure phenotype in fruit flies. We employed diverse small molecules to restore the expression and activity of folding-deficient hGAT-1 epilepsy variants, in vitro (in HEK293 cells) and in vivo (in flies). We identified three compounds (chemical and pharmacological chaperones) conferring moderate rescue capacity for several variants. Our data grant crucial new insights into: (i) the molecular basis of epilepsy in patients harboring hGAT-1 mutations, and (ii) a proof-of-principle that protein folding deficits in disease-associated hGAT-1 variants can be corrected using the pharmacochaperoning approach. Such innovative pharmaco-therapeutic prospects inspire the rational design of novel drugs for alleviating the clinical symptoms triggered by the numerous emerging pathogenic mutations in hGAT-1.
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Affiliation(s)
- Ameya S. Kasture
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria,Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Florian P. Fischer
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria,Department of Epileptology and Neurology, University of Aachen, Aachen, Germany
| | - Lisa Kunert
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Melanie L. Burger
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | | | - Ali El-Kasaby
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Thomas Hummel
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria,*Correspondence: Sonja Sucic,
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12
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Bhat S, El-Kasaby A, Kasture A, Boytsov D, Reichelt JB, Hummel T, Sucic S, Pifl C, Freissmuth M, Sandtner W. A mechanism of uncompetitive inhibition of the serotonin transporter. eLife 2023; 12:e82641. [PMID: 36648438 PMCID: PMC9883013 DOI: 10.7554/elife.82641] [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: 08/11/2022] [Accepted: 01/17/2023] [Indexed: 01/18/2023] Open
Abstract
The serotonin transporter (SERT/SLC6A4) is arguably the most extensively studied solute carrier (SLC). During its eponymous action - that is, the retrieval of serotonin from the extracellular space - SERT undergoes a conformational cycle. Typical inhibitors (antidepressant drugs and cocaine), partial and full substrates (amphetamines and their derivatives), and atypical inhibitors (ibogaine analogues) bind preferentially to different states in this cycle. This results in competitive or non-competitive transport inhibition. Here, we explored the action of N-formyl-1,3-bis (3,4-methylenedioxyphenyl)-prop-2-yl-amine (ECSI#6) on SERT: inhibition of serotonin uptake by ECSI#6 was enhanced with increasing serotonin concentration. Conversely, the KM for serotonin was lowered by augmenting ECSI#6. ECSI#6 bound with low affinity to the outward-facing state of SERT but with increased affinity to a potassium-bound state. Electrophysiological recordings showed that ECSI#6 preferentially interacted with the inward-facing state. Kinetic modeling recapitulated the experimental data and verified that uncompetitive inhibition arose from preferential binding of ECSI#6 to the K+-bound, inward-facing conformation of SERT. This binding mode predicted a pharmacochaperoning action of ECSI#6, which was confirmed by examining its effect on the folding-deficient mutant SERT-PG601,602AA: preincubation of HEK293 cells with ECSI#6 restored export of SERT-PG601,602AA from the endoplasmic reticulum and substrate transport. Similarly, in transgenic flies, the administration of ECSI#6 promoted the delivery of SERT-PG601,602AA to the presynaptic specialization of serotonergic neurons. To the best of our knowledge, ECSI#6 is the first example of an uncompetitive SLC inhibitor. Pharmacochaperones endowed with the binding mode of ECSI#6 are attractive, because they can rescue misfolded transporters at concentrations, which cause modest transport inhibition.
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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 ViennaViennaAustria
| | - 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 ViennaViennaAustria
| | - Ameya Kasture
- Department of Neurobiology, University of ViennaViennaAustria
| | - Danila Boytsov
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - Julian B Reichelt
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - Thomas Hummel
- Department of Neurobiology, University of ViennaViennaAustria
| | - Sonja Sucic
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - Christian Pifl
- Center for Brain Research, Medical University of ViennaViennaAustria
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - Walter Sandtner
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of ViennaViennaAustria
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13
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Experimental and Bioinformatic Insights into the Effects of Epileptogenic Variants on the Function and Trafficking of the GABA Transporter GAT-1. Int J Mol Sci 2023; 24:ijms24020955. [PMID: 36674476 PMCID: PMC9862756 DOI: 10.3390/ijms24020955] [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: 11/29/2022] [Revised: 12/27/2022] [Accepted: 12/31/2022] [Indexed: 01/06/2023] Open
Abstract
In this article, we identified a novel epileptogenic variant (G307R) of the gene SLC6A1, which encodes the GABA transporter GAT-1. Our main goal was to investigate the pathogenic mechanisms of this variant, located near the neurotransmitter permeation pathway, and compare it with other variants located either in the permeation pathway or close to the lipid bilayer. The mutants G307R and A334P, close to the gates of the transporter, could be glycosylated with variable efficiency and reached the membrane, albeit inactive. Mutants located in the center of the permeation pathway (G297R) or close to the lipid bilayer (A128V, G550R) were retained in the endoplasmic reticulum. Applying an Elastic Network Model, to these and to other previously characterized variants, we found that G307R and A334P significantly perturb the structure and dynamics of the intracellular gate, which can explain their reduced activity, while for A228V and G362R, the reduced translocation to the membrane quantitatively accounts for the reduced activity. The addition of a chemical chaperone (4-phenylbutyric acid, PBA), which improves protein folding, increased the activity of GAT-1WT, as well as most of the assayed variants, including G307R, suggesting that PBA might also assist the conformational changes occurring during the alternative access transport cycle.
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14
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Angenoorth TJF, Maier J, Stankovic S, Bhat S, Sucic S, Freissmuth M, Sitte HH, Yang JW. Rescue of Misfolded Organic Cation Transporter 3 Variants. Cells 2022; 12:39. [PMID: 36611832 PMCID: PMC9818475 DOI: 10.3390/cells12010039] [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: 11/18/2022] [Revised: 12/13/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Organic cation transporters (OCTs) are membrane proteins that take up monoamines, cationic drugs and xenobiotics. We previously reported novel missense mutations of organic cation transporter 3 (OCT3, SLC22A3), some with drastically impacted transport capabilities compared to wildtype. For some variants, this was due to ER retention and subsequent degradation of the misfolded transporter. For other transporter families, it was previously shown that treatment of misfolded variants with pharmacological and chemical chaperones could restore transport function to a certain degree. To investigate two potentially ER-bound, misfolded variants (D340G and R348W), we employed confocal and biochemical analyses. In addition, radiotracer uptake assays were conducted to assess whether pre-treatment with chaperones could restore transporter function. We show that pre-treatment of cells with the chemical chaperone 4-PBA (4-phenyl butyric acid) leads to increased membrane expression of misfolded variants and is associated with increased transport capacity of D340G (8-fold) and R348W (1.5 times) compared to untreated variants. We herein present proof of principle that folding-deficient SLC22 transporter variants, in particular those of OCT3, are amenable to rescue by chaperones. These findings need to be extended to other SLC22 members with corroborated disease associations.
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Affiliation(s)
- Thomas J. F. Angenoorth
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Währingerstraße 13A, 1090 Vienna, Austria
| | - Julian Maier
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Währingerstraße 13A, 1090 Vienna, Austria
| | - Stevan Stankovic
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Währingerstraße 13A, 1090 Vienna, Austria
| | - Shreyas Bhat
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Währingerstraße 13A, 1090 Vienna, Austria
- Department of Physics, Université de Montréal, 1375 Avenue Thérèse-Lavoie-Roux, Montréal, QC H3T 1J4, Canada
- Department of Pharmacology and Physiology, Université de Montréal, 2960 Chemin de la Tour, Montréal, QC H3T 1J4, Canada
| | - Sonja Sucic
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Währingerstraße 13A, 1090 Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Währingerstraße 13A, 1090 Vienna, Austria
| | - Harald H. Sitte
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Währingerstraße 13A, 1090 Vienna, Austria
| | - Jae-Won Yang
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Währingerstraße 13A, 1090 Vienna, Austria
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15
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Farr CV, El-Kasaby A, Erdem FA, Sucic S, Freissmuth M, Sandtner W. Cooperative Binding of Substrate and Ions Drives Forward Cycling of the Human Creatine Transporter-1. Front Physiol 2022; 13:919439. [PMID: 35837012 PMCID: PMC9273935 DOI: 10.3389/fphys.2022.919439] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 06/09/2022] [Indexed: 11/25/2022] Open
Abstract
Creatine serves as an ATP buffer and is thus an integral component of cellular energy metabolism. Most cells maintain their creatine levels via uptake by the creatine transporter (CRT-1, SLC6A8). The activity of CRT-1, therefore, is a major determinant of cytosolic creatine concentrations. We determined the kinetics of CRT-1 in real time by relying on electrophysiological recordings of transport-associated currents. Our analysis revealed that CRT-1 harvested the concentration gradient of NaCl and the membrane potential but not the potassium gradient to achieve a very high concentrative power. We investigated the mechanistic basis for the ability of CRT-1 to maintain the forward cycling mode in spite of high intracellular concentrations of creatine: this is achieved by cooperative binding of substrate and co-substrate ions, which, under physiological ion conditions, results in a very pronounced (i.e. about 500-fold) drop in the affinity of creatine to the inward-facing state of CRT-1. Kinetic estimates were integrated into a mathematical model of the transport cycle of CRT-1, which faithfully reproduced all experimental data. We interrogated the kinetic model to examine the most plausible mechanistic basis of cooperativity: based on this systematic exploration, we conclude that destabilization of binary rather than ternary complexes is necessary for CRT-1 to maintain the observed cytosolic creatine concentrations. Our model also provides a plausible explanation why neurons, heart and skeletal muscle cells must express a creatine releasing transporter to achieve rapid equilibration of the intracellular creatine pool.
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Affiliation(s)
| | | | | | | | - 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, Vienna, Austria
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16
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Neurotransmitters-Key Factors in Neurological and Neurodegenerative Disorders of the Central Nervous System. Int J Mol Sci 2022; 23:ijms23115954. [PMID: 35682631 PMCID: PMC9180936 DOI: 10.3390/ijms23115954] [Citation(s) in RCA: 60] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 05/22/2022] [Accepted: 05/24/2022] [Indexed: 12/14/2022] Open
Abstract
Neurotransmitters are molecules that amplify, transmit, and convert signals in cells, having an essential role in information transmission throughout the nervous system. Hundreds of such chemicals have been discovered in the last century, continuing to be identified and studied concerning their action on brain health. These substances have been observed to influence numerous functions, including emotions, thoughts, memories, learning, and movements. Thus, disturbances in neurotransmitters’ homeostasis started being correlated with a plethora of neurological and neurodegenerative disorders. In this respect, the present paper aims to describe the most important neurotransmitters, broadly classified into canonical (e.g., amino acids, monoamines, acetylcholine, purines, soluble gases, neuropeptides) and noncanonical neurotransmitters (e.g., exosomes, steroids, D-aspartic acid), and explain their link with some of the most relevant neurological conditions. Moreover, a brief overview of the recently developed neurotransmitters’ detection methods is offered, followed by several considerations on the modulation of these substances towards restoring homeostasis.
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17
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Giacomini KM, Yee SW, Koleske ML, Zou L, Matsson P, Chen EC, Kroetz DL, Miller MA, Gozalpour E, Chu X. New and Emerging Research on Solute Carrier and ATP Binding Cassette Transporters in Drug Discovery and Development: Outlook from the International Transporter Consortium. Clin Pharmacol Ther 2022; 112:540-561. [PMID: 35488474 PMCID: PMC9398938 DOI: 10.1002/cpt.2627] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 03/16/2022] [Indexed: 02/06/2023]
Abstract
Enabled by a plethora of new technologies, research in membrane transporters has exploded in the past decade. The goal of this state‐of‐the‐art article is to describe recent advances in research on membrane transporters that are particularly relevant to drug discovery and development. This review covers advances in basic, translational, and clinical research that has led to an increased understanding of membrane transporters at all levels. At the basic level, we describe the available crystal structures of membrane transporters in both the solute carrier (SLC) and ATP binding cassette superfamilies, which has been enabled by the development of cryogenic electron microscopy methods. Next, we describe new research on lysosomal and mitochondrial transporters as well as recently deorphaned transporters in the SLC superfamily. The translational section includes a summary of proteomic research, which has led to a quantitative understanding of transporter levels in various cell types and tissues and new methods to modulate transporter function, such as allosteric modulators and targeted protein degraders of transporters. The section ends with a review of the effect of the gut microbiome on modulation of transporter function followed by a presentation of 3D cell cultures, which may enable in vivo predictions of transporter function. In the clinical section, we describe new genomic and pharmacogenomic research, highlighting important polymorphisms in transporters that are clinically relevant to many drugs. Finally, we describe new clinical tools, which are becoming increasingly available to enable precision medicine, with the application of tissue‐derived small extracellular vesicles and real‐world biomarkers.
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Affiliation(s)
- Kathleen M Giacomini
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California, USA
| | - Sook W Yee
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California, USA
| | - Megan L Koleske
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California, USA
| | - Ling Zou
- Pharmacokinetics and Drug Metabolism, Amgen Inc., South San Francisco, California, USA
| | - Pär Matsson
- Department of Pharmacology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Eugene C Chen
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc., South San Francisco, California, USA
| | - Deanna L Kroetz
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California, USA
| | - Miles A Miller
- Center for Systems Biology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Elnaz Gozalpour
- Drug Safety and Metabolism, IMED Biotech Unit, Safety and ADME Translational Sciences Department, AstraZeneca R&D, Cambridge, UK
| | - Xiaoyan Chu
- Department of ADME and Discovery Toxicology, Merck & Co. Inc, Kenilworth, New Jersey, USA
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18
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Li Y, Yao W, Gao Y. Effects of Tang Luo Ning on diabetic peripheral neuropathy in rats revealed by LC-MS metabolomics approach. Biomed Chromatogr 2022; 36:e5374. [PMID: 35302257 DOI: 10.1002/bmc.5374] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 03/13/2022] [Accepted: 03/16/2022] [Indexed: 11/07/2022]
Abstract
Diabetic peripheral neuropathy (DPN) is one of the most common complications of diabetes with limited therapies. Tang Luo Ning (TLN), a traditional Chinese medicine compound, has been proved to be effective in the treatment of DPN in clinical and experimental studies. However, the potential metabolic mechanism of TLN for the treatment of DPN is still unclear. Here the therapeutic effect of TLN on DPN was studied, and HPLC-IT-TOF/MS was used to explore the metabolic changes related to DPN and to explore the mechanism of TLN on DPN induced by high glucose. Furthermore, metabolic pathway analysis was used to explore the metabolic changes induced by DPN and TLN. As a result, TLN could improve the peripheral nerve function of DPN rats, and TLN could reduce the demyelination of the sciatic nerve in DPN rats. Metabolomics analysis showed that 14 potential biomarkers (citrate, creatine, fumarate, glyceric acid, glycine, succinate, etc.) of both DPN and TLN treatment were identified. Pathway analysis showed that the changes in these metabolites were mainly related to the citrate cycle (TCA cycle), glycine, serine and threonine metabolism, and glyoxylate and dicarboxylate metabolism.
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Affiliation(s)
- Yangfan Li
- Department of Traditional Chinese Medcine, Beijing Friendship Hospital, Capital Medical University
| | - Weijie Yao
- Department of pharmacy, Beijing Maternity Hospital, Capital Medical University
| | - Yanbin Gao
- College of Traditional Chinese Medicine, Capital Medical University, No.10, Youanmenwai Xitoutiao, Fengtai District, Beijing, China
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19
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Fischer FP, Kasture AS, Hummel T, Sucic S. Molecular and Clinical Repercussions of GABA Transporter 1 Variants Gone Amiss: Links to Epilepsy and Developmental Spectrum Disorders. Front Mol Biosci 2022; 9:834498. [PMID: 35295842 PMCID: PMC7612498 DOI: 10.3389/fmolb.2022.834498] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 02/01/2022] [Indexed: 12/15/2022] Open
Abstract
The human γ-aminobutyric acid (GABA) transporter 1 (hGAT-1) is the first member of the solute carrier 6 (SLC6) protein superfamily. GAT-1 (SLC6A1) is one of the main GABA transporters in the central nervous system. Its principal physiological role is retrieving GABA from the synapse into neurons and astrocytes, thus swiftly terminating neurotransmission. GABA is a key inhibitory neurotransmitter and shifts in GABAergic signaling can lead to pathological conditions, from anxiety and epileptic seizures to schizophrenia. Point mutations in the SLC6A1 gene frequently give rise to epilepsy, intellectual disability or autism spectrum disorders in the afflicted individuals. The mechanistic routes underlying these are still fairly unclear. Some loss-of-function variants impair the folding and intracellular trafficking of the protein (thus retaining the transporter in the endoplasmic reticulum compartment), whereas others, despite managing to reach their bona fide site of action at the cell surface, nonetheless abolish GABA transport activity (plausibly owing to structural/conformational defects). Whatever the molecular culprit(s), the physiological aftermath transpires into the absence of functional transporters, which in turn perturbs GABAergic actions. Dozens of mutations in the kin SLC6 family members are known to exhort protein misfolding. Such events typically elicit severe ailments in people, e.g., infantile parkinsonism-dystonia or X-linked intellectual disability, in the case of dopamine and creatine transporters, respectively. Flaws in protein folding can be rectified by small molecules known as pharmacological and/or chemical chaperones. The search for such apt remedies calls for a systematic investigation and categorization of the numerous disease-linked variants, by biochemical and pharmacological means in vitro (in cell lines and primary neuronal cultures) and in vivo (in animal models). We here give special emphasis to the utilization of the fruit fly Drosophila melanogaster as a versatile model in GAT-1-related studies. Jointly, these approaches can portray indispensable insights into the molecular factors underlying epilepsy, and ultimately pave the way for contriving efficacious therapeutic options for patients harboring pathogenic mutations in hGAT-1.
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Affiliation(s)
- Florian P. Fischer
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
- Department of Epileptology and Neurology, University of Aachen, Aachen, Germany
| | - Ameya S. Kasture
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Thomas Hummel
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
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20
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Schicker K, Farr CV, Boytsov D, Freissmuth M, Sandtner W. Optimizing the Substrate Uptake Rate of Solute Carriers. Front Physiol 2022; 13:817886. [PMID: 35185619 PMCID: PMC8850955 DOI: 10.3389/fphys.2022.817886] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 01/10/2022] [Indexed: 11/16/2022] Open
Abstract
The diversity in solute carriers arose from evolutionary pressure. Here, we surmised that the adaptive search for optimizing the rate of substrate translocation was also shaped by the ambient extracellular and intracellular concentrations of substrate and co-substrate(s). We explored possible solutions by employing kinetic models, which were based on analytical expressions of the substrate uptake rate, that is, as a function of the microscopic rate constants used to parameterize the transport cycle. We obtained the defining terms for five reaction schemes with identical transport stoichiometry (i.e., Na+: substrate = 2:1). We then utilized an optimization algorithm to find the set of numeric values for the microscopic rate constants, which provided the largest value for the substrate uptake rate: The same optimized rate was achieved by different sets of numerical values for the microscopic rate constants. An in-depth analysis of these sets provided the following insights: (i) In the presence of a low extracellular substrate concentration, a transporter can only cycle at a high rate, if it has low values for both, the Michaelis-Menten constant (KM) for substrate and the maximal substrate uptake rate (Vmax). (ii) The opposite is true for a transporter operating at high extracellular substrate concentrations. (iii) Random order of substrate and co-substrate binding is superior to sequential order, if a transporter is to maintain a high rate of substrate uptake in the presence of accumulating intracellular substrate. Our kinetic models provide a framework to understand how and why the transport cycles of closely related transporters differ.
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Affiliation(s)
| | | | | | | | - Walter Sandtner
- Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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21
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Ponleitner M, Szöllősi D, El-Kasaby A, Koban F, Freissmuth M, Stockner T. Thermal Unfolding of the Human Serotonin Transporter: Differential Effect by Stabilizing and Destabilizing Mutations and Cholesterol on Thermodynamic and Kinetic Stability. Mol Pharmacol 2022; 101:95-105. [PMID: 34866045 DOI: 10.1124/molpharm.121.000413] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 11/21/2021] [Indexed: 11/22/2022] Open
Abstract
Folding-deficient mutants of solute carrier 6 (SLC6) family members have been linked to human diseases. The serotonin transporter [(SERT)/SLC6A4] is an important drug target in the treatment of depression, anxiety, and obsessive-compulsive disorders and-with structural information in several conformational states-one of the best understood transporters. Here, we surmised that thermal unfolding offered a glimpse on the folding energy landscape of SLC6 transporters. We carried out molecular dynamic (MD) simulations to understand the mechanistic basis for enhanced and reduced stability, respectively, of the thermostabilized variant SERT-Y110A/I291A/T439S, which had previously been used for crystallization of human SERT in the outward-facing state, and of the folding-deficient SERT-P601A/G602A. We also examined the hydrophobic mismatch caused by the absence of cholesterol to explore the contribution of cholesterol to protein stability. When compared with wild type SERT, the thermodynamic and kinetic stability of SERT-Y110A/I291A/T439S was enhanced. In the other instances, changes in these two components were not correlated: the mutations in SERT-P601A/G602A led to a drop in thermodynamic but an increase in kinetic stability. The divergence was even more pronounced after cholesterol depletion, which reduced thermodynamic stability but increased the kinetic stability of wild type SERT to a level comparable to that of SERT-Y110A/I291A/T439S. We conclude that the low cholesterol content of the endoplasmic reticulum facilitates progression of the folding trajectory by reducing the energy difference between folding intermediates and the native state. SIGNIFICANCE STATEMENT: Point mutations in solute carrier 6 (SLC6) family members cause folding diseases. The serotonin transporter [(SERT)/SLC6A4] is a target for antidepressants and the best understood SLC6. This study produced molecular dynamics simulations and examined thermal unfolding of wild type and mutant SERT variants to understand their folding energy landscape. In the folding-deficient SERT-P012A/G602A, changes in kinetic and thermodynamic stability were not correlated. Similarly, cholesterol depletion lowered thermodynamic but enhanced kinetic stability. These observations allow for rationalizing the action of pharmacochaperones.
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Affiliation(s)
- Markus Ponleitner
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Austria
| | - Daniel Szöllősi
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of 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, Austria
| | - Florian Koban
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of 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, Austria
| | - Thomas Stockner
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Austria
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22
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Occlusion of the human serotonin transporter is mediated by serotonin-induced conformational changes in the bundle domain. J Biol Chem 2022; 298:101613. [PMID: 35065961 PMCID: PMC8867121 DOI: 10.1016/j.jbc.2022.101613] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 01/16/2022] [Accepted: 01/17/2022] [Indexed: 12/04/2022] Open
Abstract
The human serotonin transporter (hSERT) terminates neurotransmission by removing serotonin (5HT) from the synaptic cleft, an essential process for proper functioning of serotonergic neurons. Structures of the hSERT have revealed its molecular architecture in four conformations, including the outward-open and occluded states, and show the transporter’s engagement with co-transported ions and the binding mode of inhibitors. In this study, we investigated the molecular mechanism by which the hSERT occludes and sequesters the substrate 5HT. This first step of substrate uptake into cells is a structural change consisting of the transition from the outward-open to the occluded state. Inhibitors such as the antidepressants citalopram, fluoxetine, and sertraline inhibit this step of the transport cycle. Using molecular dynamics simulations, we reached a fully occluded state, in which the transporter-bound 5HT becomes fully shielded from both sides of the membrane by two closed hydrophobic gates. Analysis of 5HT-triggered occlusion showed that bound 5HT serves as an essential trigger for transporter occlusion. Moreover, simulations revealed a complex sequence of steps and showed that movements of bundle domain helices are only partially correlated. 5HT-triggered occlusion is initially dominated by movements of transmembrane helix 1b, while in the final step, only transmembrane helix 6a moves and relaxes an intermediate change in its secondary structure.
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Ma L, Yuan T, Li W, Guo L, Zhu D, Wang Z, Liu Z, Xue K, Wang Y, Liu J, Man W, Ye Z, Liu F, Wang J. Dynamic Functional Connectivity Alterations and Their Associated Gene Expression Pattern in Autism Spectrum Disorders. Front Neurosci 2022; 15:794151. [PMID: 35082596 PMCID: PMC8784878 DOI: 10.3389/fnins.2021.794151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 12/16/2021] [Indexed: 12/12/2022] Open
Abstract
Autism spectrum disorders (ASDs) are a group of heterogeneous neurodevelopmental disorders that are highly heritable and are associated with impaired dynamic functional connectivity (DFC). However, the molecular mechanisms behind DFC alterations remain largely unknown. Eighty-eight patients with ASDs and 87 demographically matched typical controls (TCs) from the Autism Brain Imaging Data Exchange II database were included in this study. A seed-based sliding window approach was then performed to investigate the DFC changes in each of the 29 seeds in 10 classic resting-state functional networks and the whole brain. Subsequently, the relationships between DFC alterations in patients with ASDs and their symptom severity were assessed. Finally, transcription-neuroimaging association analyses were conducted to explore the molecular mechanisms of DFC disruptions in patients with ASDs. Compared with TCs, patients with ASDs showed significantly increased DFC between the right dorsolateral prefrontal cortex (DLPFC) and left fusiform/lingual gyrus, between the DLPFC and the superior temporal gyrus, between the right frontal eye field (FEF) and left middle frontal gyrus, between the FEF and the right angular gyrus, and between the left intraparietal sulcus and the right middle temporal gyrus. Moreover, significant relationships between DFC alterations and symptom severity were observed. Furthermore, the genes associated with DFC changes in ASDs were identified by performing gene-wise across-sample spatial correlation analysis between gene expression extracted from six donors’ brain of the Allen Human Brain Atlas and case-control DFC difference. In enrichment analysis, these genes were enriched for processes associated with synaptic signaling and voltage-gated ion channels and calcium pathways; also, these genes were highly expressed in autistic disorder, chronic alcoholic intoxication and several disorders related to depression. These results not only demonstrated higher DFC in patients with ASDs but also provided novel insight into the molecular mechanisms underlying these alterations.
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Affiliation(s)
- Lin Ma
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
| | - Tengfei Yuan
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
| | - Wei Li
- Department of Radiology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin’s Clinical Research Center for Cancer, Tianjin, China
| | - Lining Guo
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
| | - Dan Zhu
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
- Department of Radiology, Tianjin Medical University General Hospital Airport Hospital, Tianjin, China
| | - Zirui Wang
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
| | - Zhixuan Liu
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
| | - Kaizhong Xue
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
| | - Yaoyi Wang
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
| | - Jiawei Liu
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
| | - Weiqi Man
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
| | - Zhaoxiang Ye
- Department of Radiology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin’s Clinical Research Center for Cancer, Tianjin, China
- *Correspondence: Zhaoxiang Ye,
| | - Feng Liu
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
- Feng Liu,
| | - Junping Wang
- Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
- Junping Wang,
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24
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Stehantsev P, Stetsenko A, Nemchinova M, Aduri NG, Marrink SJ, Gati C, Guskov A. A structural view onto disease-linked mutations in the human neutral amino acid exchanger ASCT1. Comput Struct Biotechnol J 2021; 19:5246-5254. [PMID: 34630942 PMCID: PMC8479201 DOI: 10.1016/j.csbj.2021.09.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/14/2021] [Accepted: 09/14/2021] [Indexed: 01/30/2023] Open
Abstract
The ASCT1 transporter of the SLC1 family is largely involved in equilibration of neutral amino acids' pools across the plasma membrane and plays a prominent role in the transport of both L- and D-isomers of serine, essential for the normal functioning of the central nervous system in mammals. A number of mutations in ASCT1 (E256K, G381R, R457W) have been linked to severe neurodevelopmental disorders, however in the absence of ASCT1 structure it is hard to understand their impact on substrate transport. To ameliorate that we have determined a cryo-EM structure of human ASCT1 at 4.2 Å resolution and performed functional transport assays and molecular dynamics simulations, which revealed that given mutations lead to the diminished transport capability of ASCT1 caused by instability of transporter and impeded transport cycle.
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Affiliation(s)
- Pavlo Stehantsev
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
| | - Artem Stetsenko
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
| | - Mariia Nemchinova
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
| | - Nanda Gowtham Aduri
- Department of Biological Sciences, Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA, USA
| | - Siewert J. Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
| | - Cornelius Gati
- Department of Biological Sciences, Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA, USA
| | - Albert Guskov
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
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25
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Inhibition of Ceramide Synthesis Reduces α-Synuclein Proteinopathy in a Cellular Model of Parkinson's Disease. Int J Mol Sci 2021; 22:ijms22126469. [PMID: 34208778 PMCID: PMC8234676 DOI: 10.3390/ijms22126469] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/08/2021] [Accepted: 06/10/2021] [Indexed: 12/13/2022] Open
Abstract
Parkinson’s disease (PD) is a proteinopathy associated with the aggregation of α-synuclein and the formation of lipid–protein cellular inclusions, named Lewy bodies (LBs). LB formation results in impaired neurotransmitter release and uptake, which involve membrane traffic and require lipid synthesis and metabolism. Lipids, particularly ceramides, are accumulated in postmortem PD brains and altered in the plasma of PD patients. Autophagy is impaired in PD, reducing the ability of neurons to clear protein aggregates, thus worsening stress conditions and inducing neuronal death. The inhibition of ceramide synthesis by myriocin (Myr) in SH-SY5Y neuronal cells treated with preformed α-synuclein fibrils reduced intracellular aggregates, favoring their sequestration into lysosomes. This was associated with TFEB activation, increased expression of TFEB and LAMP2, and the cytosolic accumulation of LC3II, indicating that Myr promotes autophagy. Myr significantly reduces the fibril-related production of inflammatory mediators and lipid peroxidation and activates NRF2, which is downregulated in PD. Finally, Myr enhances the expression of genes that control neurotransmitter transport (SNARE complex, VMAT2, and DAT), whose progressive deficiency occurs in PD neurodegeneration. The present study suggests that counteracting the accumulation of inflammatory lipids could represent a possible therapeutic strategy for PD.
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26
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Ryan RM, Ingram SL, Scimemi A. Regulation of Glutamate, GABA and Dopamine Transporter Uptake, Surface Mobility and Expression. Front Cell Neurosci 2021; 15:670346. [PMID: 33927596 PMCID: PMC8076567 DOI: 10.3389/fncel.2021.670346] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 03/15/2021] [Indexed: 01/31/2023] Open
Abstract
Neurotransmitter transporters limit spillover between synapses and maintain the extracellular neurotransmitter concentration at low yet physiologically meaningful levels. They also exert a key role in providing precursors for neurotransmitter biosynthesis. In many cases, neurons and astrocytes contain a large intracellular pool of transporters that can be redistributed and stabilized in the plasma membrane following activation of different signaling pathways. This means that the uptake capacity of the brain neuropil for different neurotransmitters can be dynamically regulated over the course of minutes, as an indirect consequence of changes in neuronal activity, blood flow, cell-to-cell interactions, etc. Here we discuss recent advances in the mechanisms that control the cell membrane trafficking and biophysical properties of transporters for the excitatory, inhibitory and modulatory neurotransmitters glutamate, GABA, and dopamine.
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Affiliation(s)
- Renae M. Ryan
- School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Susan L. Ingram
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, United States
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27
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Schicker K, Bhat S, Farr C, Burtscher V, Horner A, Freissmuth M, Sandtner W. Descriptors of Secondary Active Transporter Function and How They Relate to Partial Reactions in the Transport Cycle. MEMBRANES 2021; 11:178. [PMID: 33802510 PMCID: PMC8001282 DOI: 10.3390/membranes11030178] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 02/25/2021] [Accepted: 02/27/2021] [Indexed: 12/19/2022]
Abstract
Plasmalemmal solute carriers (SLCs) gauge and control solute abundance across cellular membranes. By virtue of this action, they play an important role in numerous physiological processes. Mutations in genes encoding the SLCs alter amino acid sequence that often leads to impaired protein function and onset of monogenic disorders. To understand how these altered proteins cause disease, it is necessary to undertake relevant functional assays. These experiments reveal descriptors of SLC function such as the maximal transport velocity (Vmax), the Michaelis constant for solute uptake (KM), potencies for inhibition of transporter function (IC50/EC50), and many more. In several instances, the mutated versions of different SLC transporters differ from their wild-type counterparts in the value of these descriptors. While determination of these experimental parameters can provide conjecture as to how the mutation gives rise to disease, they seldom provide any definitive insights on how a variant differ from the wild-type transporter in its operation. This is because the experimental determination of association between values of the descriptors and several partial reactions a transporter undergoes is casual, but not causal, at best. In the present study, we employ kinetic models that allow us to derive explicit mathematical terms and provide experimental descriptors as a function of the rate constants used to parameterize the kinetic model of the transport cycle. We show that it is possible to utilize these mathematical expressions to deduce, from experimental outcomes, how the mutation has impinged on partial reactions in the transport cycle.
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Affiliation(s)
- Klaus Schicker
- Center for Physiology and Pharmacology, Division of Neurophysiology and Neuropharmacology, Medical University of Vienna, 1090 Vienna, Austria;
| | - Shreyas Bhat
- Center of Physiology and Pharmacology, Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Medical University of Vienna, 1090 Vienna, Austria; (S.B.); (C.F.); (V.B.); (M.F.)
| | - Clemens Farr
- Center of Physiology and Pharmacology, Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Medical University of Vienna, 1090 Vienna, Austria; (S.B.); (C.F.); (V.B.); (M.F.)
| | - Verena Burtscher
- Center of Physiology and Pharmacology, Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Medical University of Vienna, 1090 Vienna, Austria; (S.B.); (C.F.); (V.B.); (M.F.)
| | - Andreas Horner
- Institute of Biophysics, Johannes Kepler University Linz, 4040 Linz, Austria;
| | - Michael Freissmuth
- Center of Physiology and Pharmacology, Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Medical University of Vienna, 1090 Vienna, Austria; (S.B.); (C.F.); (V.B.); (M.F.)
| | - Walter Sandtner
- Center of Physiology and Pharmacology, Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Medical University of Vienna, 1090 Vienna, Austria; (S.B.); (C.F.); (V.B.); (M.F.)
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