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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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Wang X, Marmouzi I, Finnie PS, Støve SI, Bucher ML, Lipina TV, Ramsey AJ, Miller GW, Salahpour A. Tricyclic and tetracyclic antidepressants upregulate VMAT2 activity and rescue disease-causing VMAT2 variants. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.09.561601. [PMID: 37873339 PMCID: PMC10592782 DOI: 10.1101/2023.10.09.561601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Vesicular monoamine transporter 2 (VMAT2) is an essential transporter that regulates brain monoamine transmission and is important for mood, cognition, motor activity, and stress regulation. However, VMAT2 remains underexplored as a pharmacological target. In this study, we report that tricyclic and tetracyclic antidepressants acutely inhibit, but persistently upregulate VMAT2 activity by promoting VMAT2 protein maturation. Importantly, the VMAT2 upregulation effect was greater in BE(2)-M17 cells that endogenously express VMAT2 as compared to a heterologous expression system (HEK293). The net sustained effect of tricyclics and tetracyclics is an upregulation of VMAT2 activity, despite their acute inhibitory effect. Furthermore, imipramine and mianserin, two representative compounds, also demonstrated rescue of nine VMAT2 variants that cause Brain Vesicular Monoamine Transport Disease (BVMTD). VMAT2 upregulation could be beneficial for disorders associated with reduced monoamine transmission, including mood disorders and BVMTD, a rare but often fatal condition caused by a lack of functional VMAT2. Our findings provide the first evidence that small molecules can upregulate VMAT2 and have potential therapeutic benefit for various neuropsychiatric conditions.
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3
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Koban F, Freissmuth M. The cell cycle protein MAD2 facilitates endocytosis of the serotonin transporter in the neuronal soma. EMBO Rep 2023; 24:e53408. [PMID: 37530743 PMCID: PMC10561363 DOI: 10.15252/embr.202153408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 06/23/2023] [Accepted: 07/14/2023] [Indexed: 08/03/2023] Open
Abstract
Monoamine transporters retrieve serotonin (SERT), dopamine (DAT), and norepinephrine (NET) from the synaptic cleft. Transporter internalization contributes to the regulation of their surface expression. Clathrin-mediated endocytosis of plasma membrane proteins requires adaptor protein-2 (AP2), which recruits cargo to the nascent clathrin cage. However, the intracellular portions of monoamine transporters are devoid of a conventional AP2-binding site. Here, we identify a MAD2 (mitotic arrest deficient-2) interaction motif in the C-terminus of SERT, which binds the closed conformation of MAD2 and allows for the recruitment of two additional mitotic spindle assembly checkpoint (SAC) proteins, BubR1 and p31comet , and of AP2. We visualize MAD2, BubR1, and p31comet in dorsal raphe neurons, and depletion of MAD2 in primary serotonergic rat neurons decreases SERT endocytosis in the soma. Our findings do not only provide mechanistic insights into transporter internalization but also allow for rationalizing why SAC proteins are present in post-mitotic neurons.
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Affiliation(s)
- Florian Koban
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and PharmacologyMedical University of ViennaViennaAustria
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and PharmacologyMedical University of ViennaViennaAustria
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4
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Acero VP, Cribas ES, Browne KD, Rivellini O, Burrell JC, O’Donnell JC, Das S, Cullen DK. Bedside to bench: the outlook for psychedelic research. Front Pharmacol 2023; 14:1240295. [PMID: 37869749 PMCID: PMC10588653 DOI: 10.3389/fphar.2023.1240295] [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: 06/14/2023] [Accepted: 08/30/2023] [Indexed: 10/24/2023] Open
Abstract
There has recently been a resurgence of interest in psychedelic compounds based on studies demonstrating their potential therapeutic applications in treating post-traumatic stress disorder, substance abuse disorders, and treatment-resistant depression. Despite promising efficacy observed in some clinical trials, the full range of biological effects and mechanism(s) of action of these compounds have yet to be fully established. Indeed, most studies to date have focused on assessing the psychological mechanisms of psychedelics, often neglecting the non-psychological modes of action. However, it is important to understand that psychedelics may mediate their therapeutic effects through multi-faceted mechanisms, such as the modulation of brain network activity, neuronal plasticity, neuroendocrine function, glial cell regulation, epigenetic processes, and the gut-brain axis. This review provides a framework supporting the implementation of a multi-faceted approach, incorporating in silico, in vitro and in vivo modeling, to aid in the comprehensive understanding of the physiological effects of psychedelics and their potential for clinical application beyond the treatment of psychiatric disorders. We also provide an overview of the literature supporting the potential utility of psychedelics for the treatment of brain injury (e.g., stroke and traumatic brain injury), neurodegenerative diseases (e.g., Parkinson's and Alzheimer's diseases), and gut-brain axis dysfunction associated with psychiatric disorders (e.g., generalized anxiety disorder and major depressive disorder). To move the field forward, we outline advantageous experimental frameworks to explore these and other novel applications for psychedelics.
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Affiliation(s)
- Victor P. Acero
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, United States
- Penn Psychedelics Collaborative, University of Pennsylvania, Philadelphia, PA, United States
| | - Emily S. Cribas
- Penn Psychedelics Collaborative, University of Pennsylvania, Philadelphia, PA, United States
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Kevin D. Browne
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
| | - Olivia Rivellini
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
- Penn Psychedelics Collaborative, University of Pennsylvania, Philadelphia, PA, United States
| | - Justin C. Burrell
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, United States
| | - John C. O’Donnell
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
- Penn Psychedelics Collaborative, University of Pennsylvania, Philadelphia, PA, United States
| | - Suradip Das
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
| | - D. Kacy Cullen
- Center for Brain Injury and Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Center for Neurotrauma, Neurodegeneration and Restoration, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, United States
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, United States
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5
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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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6
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Ng J, Barral S, Waddington SN, Kurian MA. Dopamine Transporter Deficiency Syndrome (DTDS): Expanding the Clinical Phenotype and Precision Medicine Approaches. Cells 2023; 12:1737. [PMID: 37443770 PMCID: PMC10341083 DOI: 10.3390/cells12131737] [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: 02/21/2023] [Revised: 06/16/2023] [Accepted: 06/23/2023] [Indexed: 07/15/2023] Open
Abstract
Infantile parkinsonism-dystonia due to dopamine transporter deficiency syndrome (DTDS) is an ultrarare childhood movement disorder caused by biallelic loss-of-function mutations in the SLC6A3 gene. Advances in genomic analysis have revealed an evolving spectrum of SLC6A3-related neurological and neuropsychiatric disorders. Since the initial clinical and genetic characterisation of DTDS in 2009, there have been thirty-one published cases with a variety of protein-truncating variants (nonsense variants, splice-site changes, and deletions) and missense changes. Amino acid substitutions result in mutant proteins with impaired dopamine transporter function due to reduced transporter activity, impaired dopamine binding, reduced cell-surface expression, and aberrant posttranslational protein modification with impaired glycosylation. In this review, we provide an overview of the expanding clinical phenotype of DTDS and the precision therapies in development, including pharmacochaperones and gene therapy.
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Affiliation(s)
- Joanne Ng
- Gene Transfer Technology Group, EGA UCL Institute for Women’s Health, University College London, London WC1E 6HX, UK; (J.N.); (S.N.W.)
- Genetic Therapy Accelerator Centre, Queens Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Serena Barral
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, GOS UCL Institute of Child Health, University College London, London WC1N 1DZ, UK;
| | - Simon N. Waddington
- Gene Transfer Technology Group, EGA UCL Institute for Women’s Health, University College London, London WC1E 6HX, UK; (J.N.); (S.N.W.)
- Wits/SAMRC Antiviral Gene Therapy Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa
| | - Manju A. Kurian
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, GOS UCL Institute of Child Health, University College London, London WC1N 1DZ, UK;
- Paediatric Neurology, Great Ormond Street Hospital for Children, London WC1N 3JH, UK
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7
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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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8
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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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9
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Kearney PJ, Bolden NC, Kahuno E, Conklin TL, Martin GE, Lubec G, Melikian HE. Presynaptic Gq-coupled receptors drive biphasic dopamine transporter trafficking that modulates dopamine clearance and motor function. J Biol Chem 2023; 299:102900. [PMID: 36640864 PMCID: PMC9943899 DOI: 10.1016/j.jbc.2023.102900] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 12/23/2022] [Accepted: 01/03/2023] [Indexed: 01/13/2023] Open
Abstract
Extracellular dopamine (DA) levels are constrained by the presynaptic DA transporter (DAT), a major psychostimulant target. Despite its necessity for DA neurotransmission, DAT regulation in situ is poorly understood, and it is unknown whether regulated DAT trafficking impacts dopaminergic signaling and/or behaviors. Leveraging chemogenetics and conditional gene silencing, we found that activating presynaptic Gq-coupled receptors, either hM3Dq or mGlu5, drove rapid biphasic DAT membrane trafficking in ex vivo striatal slices, with region-specific differences between ventral and dorsal striata. DAT insertion required D2 DA autoreceptors and intact retromer, whereas DAT retrieval required PKC activation and Rit2. Ex vivo voltammetric studies revealed that DAT trafficking impacts DA clearance. Furthermore, dopaminergic mGlu5 silencing elevated DAT surface expression and abolished motor learning, which was rescued by inhibiting DAT with a subthreshold CE-158 dose. We discovered that presynaptic DAT trafficking is complex, multimodal, and region specific, and for the first time, we identified cell autonomous mechanisms that govern presynaptic DAT tone. Importantly, the findings are consistent with a role for regulated DAT trafficking in DA clearance and motor function.
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Affiliation(s)
- Patrick J. Kearney
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Chan Medical School, Worcester, Massachusetts, USA,Morningside Graduate School of Biomedical Sciences, UMASS Chan Medical School, Worcester, Massachusetts, USA
| | - Nicholas C. Bolden
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Chan Medical School, Worcester, Massachusetts, USA,Morningside Graduate School of Biomedical Sciences, UMASS Chan Medical School, Worcester, Massachusetts, USA
| | - Elizabeth Kahuno
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Chan Medical School, Worcester, Massachusetts, USA
| | - Tucker L. Conklin
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Chan Medical School, Worcester, Massachusetts, USA
| | - Gilles E. Martin
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Chan Medical School, Worcester, Massachusetts, USA
| | - Gert Lubec
- Department of Neuroproteomics, Paracelsus Private Medical University, Salzburg, Austria
| | - Haley E. Melikian
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, UMASS Chan Medical School, Worcester, Massachusetts, USA,For correspondence: Haley E. Melikian
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10
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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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11
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Vorobyeva N, Kozlova AA. Three Naturally-Occurring Psychedelics and Their Significance in the Treatment of Mental Health Disorders. Front Pharmacol 2022; 13:927984. [PMID: 35837277 PMCID: PMC9274002 DOI: 10.3389/fphar.2022.927984] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/06/2022] [Indexed: 12/20/2022] Open
Abstract
Classical psychedelics represent a family of psychoactive substances with structural similarities to serotonin and affinity for serotonin receptors. A growing number of studies have found that psychedelics can be effective in treating various psychiatric conditions, including post-traumatic stress disorder, major depressive disorder, anxiety, and substance use disorders. Mental health disorders are extremely prevalent in the general population constituting a major problem for the public health. There are a wide variety of interventions for mental health disorders, including pharmacological therapies and psychotherapies, however, treatment resistance still remains a particular challenge in this field, and relapse rates are also quite high. In recent years, psychedelics have become one of the promising new tools for the treatment of mental health disorders. In this review, we will discuss the three classic serotonergic naturally occurring psychedelics, psilocybin, ibogaine, and N, N-dimethyltryptamine, focusing on their pharmacological properties and clinical potential. The purpose of this article is to provide a focused review of the most relevant research into the therapeutic potential of these substances and their possible integration as alternative or adjuvant options to existing pharmacological and psychological therapies.
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Affiliation(s)
- Nataliya Vorobyeva
- Hive Bio Life Sciences Ltd., London, United Kingdom
- *Correspondence: Nataliya Vorobyeva,
| | - Alena A. Kozlova
- Department of Psychiatry and Psychotherapy, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
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12
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Sutton C, Williams EQ, Homsi H, Beerepoot P, Nazari R, Han D, Ramsey AJ, Mash DC, Olson DE, Blough B, Salahpour A. Structure-Activity Relationships of Dopamine Transporter Pharmacological Chaperones. Front Cell Neurosci 2022; 16:832536. [PMID: 35614973 PMCID: PMC9124866 DOI: 10.3389/fncel.2022.832536] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 03/21/2022] [Indexed: 11/13/2022] Open
Abstract
Mutations in the dopamine transporter gene (SLC6A3) have been implicated in many human diseases. Among these is the infantile parkinsonism-dystonia known as Dopamine Transporter Deficiency Syndrome (DTDS). Afflicted individuals have minimal to no functional dopamine transporter protein. This is primarily due to retention of misfolded disease-causing dopamine transporter variants. This results in a variety of severe motor symptoms in patients and the disease ultimately leads to death in adolescence or young adulthood. Though no treatment is currently available, pharmacological chaperones targeting the dopamine transporter have been shown to rescue select DTDS disease-causing variants. Previous work has identified two DAT pharmacological chaperones with moderate potency and efficacy: bupropion and ibogaine. In this study, we carried out structure-activity relationships (SARs) for bupropion and ibogaine with the goal of identifying the chemical features required for pharmacological chaperone activity. Our results show that the isoquinuclidine substituent of ibogaine and its analogs is an important feature for pharmacological chaperone efficacy. For bupropion, the secondary amine group is essential for pharmacological chaperone activity. Lastly, we describe additional ibogaine and bupropion analogs with varying chemical modifications and variable pharmacological chaperone efficacies at the dopamine transporter. Our results contribute to the design and refinement of future dopamine transporter pharmacological chaperones with improved efficacies and potencies.
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Affiliation(s)
- Charles Sutton
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Erin Q. Williams
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Hoomam Homsi
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Pieter Beerepoot
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Reza Nazari
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Dong Han
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Amy J. Ramsey
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Deborah C. Mash
- Departments of Neurology and Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL, United States
| | - David E. Olson
- Department of Chemistry, College of Letters and Science, University of California, Davis, Davis, CA, United States
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA, United States
- Center for Neuroscience, University of California, Davis, Davis, CA, United States
| | - Bruce Blough
- Center for Drug Discovery, RTI International, North Carolina, NC, United States
| | - Ali Salahpour
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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13
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Rahul, Siddique YH. Drosophila: A Model to Study the Pathogenesis of Parkinson's Disease. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2022; 21:259-277. [PMID: 35040399 DOI: 10.2174/1871527320666210809120621] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 02/15/2021] [Accepted: 06/13/2021] [Indexed: 12/12/2022]
Abstract
Human Central Nervous System (CNS) is the complex part of the human body, which regulates multiple cellular and molecular events taking place simultaneously. Parkinsons Disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease (AD). The pathological hallmarks of PD are loss of dopaminergic neurons in the substantianigra (SN) pars compacta (SNpc) and accumulation of misfolded α-synuclein, in intra-cytoplasmic inclusions called Lewy bodies (LBs). So far, there is no cure for PD, due to the complexities of molecular mechanisms and events taking place during the pathogenesis of PD. Drosophila melanogaster is an appropriate model organism to unravel the pathogenicity not only behind PD but also other NDs. In this context as numerous biological functions are preserved between Drosophila and humans. Apart from sharing 75% of human disease-causing genes homolog in Drosophila, behavioral responses like memory-based tests, negative geotaxis, courtship and mating are also well studied. The genetic, as well as environmental factors, can be studied in Drosophila to understand the geneenvironment interactions behind the disease condition. Through genetic manipulation, mutant flies can be generated harboring human orthologs, which can prove to be an excellent model to understand the effect of the mutant protein on the pathogenicity of NDs.
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Affiliation(s)
- Rahul
- Drosophila Transgenic Laboratory, Section of Genetics, Department of Zoology, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, 202002, Uttar Pradesh,India
| | - Yasir Hasan Siddique
- Drosophila Transgenic Laboratory, Section of Genetics, Department of Zoology, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, 202002, Uttar Pradesh,India
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14
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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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15
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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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16
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Emran MY, El‐Safty SA, Elmarakbi A, Reda A, El Sabagh A, Shenashen MA. Chipset Nanosensor Based on N‐Doped Carbon Nanobuds for Selective Screening of Epinephrine in Human Samples. ADVANCED MATERIALS INTERFACES 2022; 9. [DOI: 10.1002/admi.202101473] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Indexed: 09/01/2023]
Abstract
AbstractChipset nanosensor design and fabrication are important for healthcare research and development. Herein, a functionalized chipset nanosensor is designed to monitor neurotransmitters (i.e., epinephrine (EP)) in human fluids. An interdigitated electrode array (IDA) is functionalized by N‐doped carbon nanobud (N‐CNB) and N‐doped carbon nanostructure (N‐CNS). The surface morphology of N‐CNB shows the formation of nanotubular‐like branches on sheets and micrometer‐size tubes. The N‐CNS design consists of the formation of aggregated sheets and particles in nanometer size. The irregular shape formation provides surface heterogeneity and numerous free spaces between the stacked nanostructures. N‐atoms ascertain highly active N‐CNS with multifunctional active centers, electron‐rich charged surface, and short distance pathway. The N‐CNB/IDA exhibits the best performance for EP signaling with high sensitivity and selectivity. The N‐CNB/IDA sensing performance for EP detection indicates the successful design of a highly selective and sensitive assay with low detection limit of 0.011 × 10−6 m and a broad linear range of 0.5 × 10−6 to 3 × 10−6 m. The N‐CNB/IDA exhibits a high degree of accuracy and reproducibility with RSD of 2.7% and 3.9%, respectively. Therefore, the chipset nanosensor of N‐CNB/IDA can be used for on‐site monitoring of EP in human serum samples and further used in daily monitoring of neuronal disorders.
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Affiliation(s)
- Mohammed Y. Emran
- National Institute for Materials Science (NIMS) Research Center for Functional Materials 1‐2‐1 Sengen Tsukuba‐shi Ibaraki‐ken 305‐0047 Japan
| | - Sherif A. El‐Safty
- National Institute for Materials Science (NIMS) Research Center for Functional Materials 1‐2‐1 Sengen Tsukuba‐shi Ibaraki‐ken 305‐0047 Japan
| | - Ahmed Elmarakbi
- Faculty of Engineering and Environment Northumbria University Newcastle upon Tyne NE1 8ST UK
| | - Abduallah Reda
- National Institute for Materials Science (NIMS) Research Center for Functional Materials 1‐2‐1 Sengen Tsukuba‐shi Ibaraki‐ken 305‐0047 Japan
| | - Ayman El Sabagh
- Department of Field Crops Faculty of Agriculture Siirt University Siirt 56100 Turkey
| | - Mohamed A. Shenashen
- National Institute for Materials Science (NIMS) Research Center for Functional Materials 1‐2‐1 Sengen Tsukuba‐shi Ibaraki‐ken 305‐0047 Japan
- Department of Petrochemical Egyptian Petroleum Research Institute (EPRI) Nasr City Cairo 11727 Egypt
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17
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Mermer F, Poliquin S, Rigsby K, Rastogi A, Shen W, Romero-Morales A, Nwosu G, McGrath P, Demerast S, Aoto J, Bilousova G, Lal D, Gama V, Kang JQ. Common molecular mechanisms of SLC6A1 variant-mediated neurodevelopmental disorders in astrocytes and neurons. Brain 2021; 144:2499-2512. [PMID: 34028503 PMCID: PMC8418336 DOI: 10.1093/brain/awab207] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 05/11/2021] [Accepted: 05/17/2021] [Indexed: 11/13/2022] Open
Abstract
Solute carrier family 6 member 1 (SLC6A1) is abundantly expressed in the developing brain even before the CNS is formed. Its encoded GABA transporter 1 (GAT-1) is responsible for the reuptake of GABA into presynaptic neurons and glia, thereby modulating neurotransmission. GAT-1 is expressed globally in the brain, in both astrocytes and neurons. The GABA uptake function of GAT-1 in neurons cannot be compensated for by other GABA transporters, while the function in glia can be partially replaced by GABA transporter 3. Recently, many variants in SLC6A1 have been associated with a spectrum of epilepsy syndromes and neurodevelopmental disorders, including myoclonic atonic epilepsy, childhood absence epilepsy, autism, and intellectual disability, but the pathomechanisms associated with these phenotypes remain unclear. The presence of GAT-1 in both neurons and astrocytes further obscures the role of abnormal GAT-1 in the heterogeneous disease phenotype manifestations. Here we examine the impact on transporter trafficking and function of 22 SLC6A1 variants identified in patients with a broad spectrum of phenotypes. We also evaluate changes in protein expression and subcellular localization of the variant GAT-1 in various cell types, including neurons and astrocytes derived from human patient induced pluripotent stem cells. We found that a partial or complete loss-of-function represents a common disease mechanism, although the extent of GABA uptake reduction is variable. The reduced GABA uptake appears to be due to reduced cell surface expression of the variant transporter caused by variant protein misfolding, endoplasmic reticulum retention, and subsequent degradation. Although the extent of reduction of the total protein, surface protein, and the GABA uptake level of the variant transporters is variable, the loss of GABA uptake function and endoplasmic reticulum retention is consistent across induced pluripotent stem cell-derived cell types, including astrocytes and neurons, for the surveyed variants. Interestingly, we did not find a clear correlation of GABA uptake function and the disease phenotypes, such as myoclonic atonic epilepsy versus developmental delay, in this study. Together, our study suggests that impaired transporter protein trafficking and surface expression are the major disease-associated mechanisms associated with pathogenic SLC6A1 variants. Our results resemble findings from pathogenic variants in other genes affecting the GABA pathway, such as GABAA receptors. This study provides critical insight into therapeutic developments for SLC6A1 variant-mediated disorders and implicates that boosting transporter function by either genetic or pharmacological approaches would be beneficial.
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Affiliation(s)
- Felicia Mermer
- 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 37232, USA
| | | | - Anuj Rastogi
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Wangzhen Shen
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Alejandra Romero-Morales
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Stem Cell Biology, Nashville, TN 37232, USA
| | - Gerald Nwosu
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt-Meharry Alliance Vanderbilt University, Nashville, TN 37232, USA
| | - Patrick McGrath
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Scott Demerast
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Jason Aoto
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Ganna Bilousova
- Department of Dermatology, Charles C. Gates Center for Regenerative Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Dennis Lal
- Cleveland Clinic Genomic Medicine Institute and Neurological Institute, Cleveland, OH 44195, USA
| | - Vivian Gama
- Neuroscience Graduate Program, Vanderbilt University, Nashville, TN 37232, USA
- Vanderbilt Brain Institute, Nashville, TN 37232, USA
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Stem Cell Biology, Nashville, TN 37232, USA
| | - Jing-Qiong Kang
- 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 37232, USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
- Vanderbilt Kennedy Center of Human Development, Nashville, TN 37232, USA
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18
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Ng J, Barral S, De La Fuente Barrigon C, Lignani G, Erdem FA, Wallings R, Privolizzi R, Rossignoli G, Alrashidi H, Heasman S, Meyer E, Ngoh A, Pope S, Karda R, Perocheau D, Baruteau J, Suff N, Antinao Diaz J, Schorge S, Vowles J, Marshall LR, Cowley SA, Sucic S, Freissmuth M, Counsell JR, Wade-Martins R, Heales SJR, Rahim AA, Bencze M, Waddington SN, Kurian MA. Gene therapy restores dopamine transporter expression and ameliorates pathology in iPSC and mouse models of infantile parkinsonism. Sci Transl Med 2021; 13:eaaw1564. [PMID: 34011628 PMCID: PMC7612279 DOI: 10.1126/scitranslmed.aaw1564] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 08/20/2020] [Accepted: 02/20/2021] [Indexed: 12/11/2022]
Abstract
Most inherited neurodegenerative disorders are incurable, and often only palliative treatment is available. Precision medicine has great potential to address this unmet clinical need. We explored this paradigm in dopamine transporter deficiency syndrome (DTDS), caused by biallelic loss-of-function mutations in SLC6A3, encoding the dopamine transporter (DAT). Patients present with early infantile hyperkinesia, severe progressive childhood parkinsonism, and raised cerebrospinal fluid dopamine metabolites. The absence of effective treatments and relentless disease course frequently leads to death in childhood. Using patient-derived induced pluripotent stem cells (iPSCs), we generated a midbrain dopaminergic (mDA) neuron model of DTDS that exhibited marked impairment of DAT activity, apoptotic neurodegeneration associated with TNFα-mediated inflammation, and dopamine toxicity. Partial restoration of DAT activity by the pharmacochaperone pifithrin-μ was mutation-specific. In contrast, lentiviral gene transfer of wild-type human SLC6A3 complementary DNA restored DAT activity and prevented neurodegeneration in all patient-derived mDA lines. To progress toward clinical translation, we used the knockout mouse model of DTDS that recapitulates human disease, exhibiting parkinsonism features, including tremor, bradykinesia, and premature death. Neonatal intracerebroventricular injection of human SLC6A3 using an adeno-associated virus (AAV) vector provided neuronal expression of human DAT, which ameliorated motor phenotype, life span, and neuronal survival in the substantia nigra and striatum, although off-target neurotoxic effects were seen at higher dosage. These were avoided with stereotactic delivery of AAV2.SLC6A3 gene therapy targeted to the midbrain of adult knockout mice, which rescued both motor phenotype and neurodegeneration, suggesting that targeted AAV gene therapy might be effective for patients with DTDS.
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Affiliation(s)
- Joanne Ng
- Gene Transfer Technology Group, EGA-Institute for Women's Health, University College London, London, WC1E 6HX, UK
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, GOS-Institute of Child Health, University College London, London, WC1N 1DZ, UK
| | - Serena Barral
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, GOS-Institute of Child Health, University College London, London, WC1N 1DZ, UK.
| | | | - Gabriele Lignani
- Clinical and Experimental Epilepsy, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Fatma A Erdem
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, GOS-Institute of Child Health, University College London, London, WC1N 1DZ, UK
- Institute of Pharmacology and Gaston H. Glock Laboratories for Exploratory Drug Research, Centre of Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Rebecca Wallings
- Oxford Parkinson's Disease Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK
| | - Riccardo Privolizzi
- Gene Transfer Technology Group, EGA-Institute for Women's Health, University College London, London, WC1E 6HX, UK
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, GOS-Institute of Child Health, University College London, London, WC1N 1DZ, UK
| | - Giada Rossignoli
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, GOS-Institute of Child Health, University College London, London, WC1N 1DZ, UK
| | - Haya Alrashidi
- Genetics and Genomic Medicine, GOS-Institute of Child Health, University College London, London, WC1N 1EH, UK
| | - Sonja Heasman
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, GOS-Institute of Child Health, University College London, London, WC1N 1DZ, UK
| | - Esther Meyer
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, GOS-Institute of Child Health, University College London, London, WC1N 1DZ, UK
| | - Adeline Ngoh
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, GOS-Institute of Child Health, University College London, London, WC1N 1DZ, UK
| | - Simon Pope
- Neurometabolic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Rajvinder Karda
- Gene Transfer Technology Group, EGA-Institute for Women's Health, University College London, London, WC1E 6HX, UK
| | - Dany Perocheau
- Gene Transfer Technology Group, EGA-Institute for Women's Health, University College London, London, WC1E 6HX, UK
| | - Julien Baruteau
- Gene Transfer Technology Group, EGA-Institute for Women's Health, University College London, London, WC1E 6HX, UK
- Genetics and Genomic Medicine, GOS-Institute of Child Health, University College London, London, WC1N 1EH, UK
| | - Natalie Suff
- Gene Transfer Technology Group, EGA-Institute for Women's Health, University College London, London, WC1E 6HX, UK
- Department of Women and Children's Health, King's College London, London, WC2R 2LS, UK
| | - Juan Antinao Diaz
- Gene Transfer Technology Group, EGA-Institute for Women's Health, University College London, London, WC1E 6HX, UK
| | - Stephanie Schorge
- Clinical and Experimental Epilepsy, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
- Pharmacology, School of Pharmacy, University College London, London, WC1N 1AX, UK
| | - Jane Vowles
- James Martin Stem Cell Facility, Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Lucy R Marshall
- Infection, Immunity, Inflammation, GOS-Institute of Child Health, University College London, London, WC1N 1EH, UK
| | - Sally A Cowley
- James Martin Stem Cell Facility, Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Sonja Sucic
- Institute of Pharmacology and Gaston H. Glock Laboratories for Exploratory Drug Research, Centre of Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology and Gaston H. Glock Laboratories for Exploratory Drug Research, Centre of Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria
| | - John R Counsell
- Developmental Neurosciences, GOS-Institute of Child Health, University College London, London, WC1N 1EH, UK
| | - Richard Wade-Martins
- Oxford Parkinson's Disease Centre, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK
| | - Simon J R Heales
- Genetics and Genomic Medicine, GOS-Institute of Child Health, University College London, London, WC1N 1EH, UK
- Neurometabolic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
| | - Ahad A Rahim
- Pharmacology, School of Pharmacy, University College London, London, WC1N 1AX, UK
| | - Maximilien Bencze
- Developmental Neurosciences, GOS-Institute of Child Health, University College London, London, WC1N 1EH, UK
- University Paris Est Creteil, INSERM, IMRB, 94000 Creteil, France
| | - Simon N Waddington
- Gene Transfer Technology Group, EGA-Institute for Women's Health, University College London, London, WC1E 6HX, UK.
- Wits/SAMRC Antiviral Gene Therapy Research Unit, Faculty of Health Sciences, University of the Witwatersrand, 2193 Johannesburg, South Africa
| | - Manju A Kurian
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, GOS-Institute of Child Health, University College London, London, WC1N 1DZ, UK
- Department of Neurology, Great Ormond Street Hospital for Children, London, WC1N 3JH, UK
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19
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Aguilar JI, Cheng MH, Font J, Schwartz AC, Ledwitch K, Duran A, Mabry SJ, Belovich AN, Zhu Y, Carter AM, Shi L, Kurian MA, Fenollar-Ferrer C, Meiler J, Ryan RM, Mchaourab HS, Bahar I, Matthies HJ, Galli A. Psychomotor impairments and therapeutic implications revealed by a mutation associated with infantile Parkinsonism-Dystonia. eLife 2021; 10:68039. [PMID: 34002696 PMCID: PMC8131106 DOI: 10.7554/elife.68039] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 05/02/2021] [Indexed: 12/30/2022] Open
Abstract
Parkinson disease (PD) is a progressive, neurodegenerative disorder affecting over 6.1 million people worldwide. Although the cause of PD remains unclear, studies of highly penetrant mutations identified in early-onset familial parkinsonism have contributed to our understanding of the molecular mechanisms underlying disease pathology. Dopamine (DA) transporter (DAT) deficiency syndrome (DTDS) is a distinct type of infantile parkinsonism-dystonia that shares key clinical features with PD, including motor deficits (progressive bradykinesia, tremor, hypomimia) and altered DA neurotransmission. Here, we define structural, functional, and behavioral consequences of a Cys substitution at R445 in human DAT (hDAT R445C), identified in a patient with DTDS. We found that this R445 substitution disrupts a phylogenetically conserved intracellular (IC) network of interactions that compromise the hDAT IC gate. This is demonstrated by both Rosetta molecular modeling and fine-grained simulations using hDAT R445C, as well as EPR analysis and X-ray crystallography of the bacterial homolog leucine transporter. Notably, the disruption of this IC network of interactions supported a channel-like intermediate of hDAT and compromised hDAT function. We demonstrate that Drosophila melanogaster expressing hDAT R445C show impaired hDAT activity, which is associated with DA dysfunction in isolated brains and with abnormal behaviors monitored at high-speed time resolution. We show that hDAT R445C Drosophila exhibit motor deficits, lack of motor coordination (i.e. flight coordination) and phenotypic heterogeneity in these behaviors that is typically associated with DTDS and PD. These behaviors are linked with altered dopaminergic signaling stemming from loss of DA neurons and decreased DA availability. We rescued flight coordination with chloroquine, a lysosomal inhibitor that enhanced DAT expression in a heterologous expression system. Together, these studies shed some light on how a DTDS-linked DAT mutation underlies DA dysfunction and, possibly, clinical phenotypes shared by DTDS and PD.
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Affiliation(s)
- Jenny I Aguilar
- Department of Pharmacology, Vanderbilt University, Nashville, United States.,Department of Surgery, University of Alabama at Birmingham, Birmingham, United States
| | - Mary Hongying Cheng
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, United States
| | - Josep Font
- School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - Alexandra C Schwartz
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, United States
| | - Kaitlyn Ledwitch
- Center for Structural Biology, Vanderbilt University, Nashville, United States.,Department of Chemistry, Vanderbilt University, Nashville, United States
| | - Amanda Duran
- Center for Structural Biology, Vanderbilt University, Nashville, United States.,Department of Chemistry, Vanderbilt University, Nashville, United States
| | - Samuel J Mabry
- Department of Surgery, University of Alabama at Birmingham, Birmingham, United States
| | - Andrea N Belovich
- Department of Biomedical Sciences, Idaho College of Osteopathic Medicine, Meridian, United States
| | - Yanqi Zhu
- Department of Surgery, University of Alabama at Birmingham, Birmingham, United States
| | - Angela M Carter
- Department of Surgery, University of Alabama at Birmingham, Birmingham, United States
| | - Lei Shi
- Computational Chemistry and Molecular Biophysics Section, NIDA, NIH, Baltimore, United States
| | - Manju A Kurian
- Molecular Neurosciences, Developmental Neurosciences, University College London (UCL), London, United Kingdom
| | | | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, United States.,Department of Chemistry, Vanderbilt University, Nashville, United States.,Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany
| | - Renae Monique Ryan
- School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - Hassane S Mchaourab
- Department of Molecular Physiology & Biophysics, Vanderbilt University, Nashville, United States
| | - Ivet Bahar
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, United States
| | - Heinrich Jg Matthies
- Department of Surgery, University of Alabama at Birmingham, Birmingham, United States
| | - Aurelio Galli
- Department of Surgery, University of Alabama at Birmingham, Birmingham, United States.,Center for Inter-systemic Networks and Enteric Medical Advances, University of Alabama at Birmingham, Birmingham, United States
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20
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Cumming P, Scheidegger M, Dornbierer D, Palner M, Quednow BB, Martin-Soelch C. Molecular and Functional Imaging Studies of Psychedelic Drug Action in Animals and Humans. Molecules 2021; 26:2451. [PMID: 33922330 PMCID: PMC8122807 DOI: 10.3390/molecules26092451] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/15/2021] [Accepted: 04/19/2021] [Indexed: 12/19/2022] Open
Abstract
Hallucinogens are a loosely defined group of compounds including LSD, N,N-dimethyltryptamines, mescaline, psilocybin/psilocin, and 2,5-dimethoxy-4-methamphetamine (DOM), which can evoke intense visual and emotional experiences. We are witnessing a renaissance of research interest in hallucinogens, driven by increasing awareness of their psychotherapeutic potential. As such, we now present a narrative review of the literature on hallucinogen binding in vitro and ex vivo, and the various molecular imaging studies with positron emission tomography (PET) or single photon emission computer tomography (SPECT). In general, molecular imaging can depict the uptake and binding distribution of labelled hallucinogenic compounds or their congeners in the brain, as was shown in an early PET study with N1-([11C]-methyl)-2-bromo-LSD ([11C]-MBL); displacement with the non-radioactive competitor ketanserin confirmed that the majority of [11C]-MBL specific binding was to serotonin 5-HT2A receptors. However, interactions at serotonin 5HT1A and other classes of receptors and pleotropic effects on second messenger pathways may contribute to the particular experiential phenomenologies of LSD and other hallucinogenic compounds. Other salient aspects of hallucinogen action include permeability to the blood-brain barrier, the rates of metabolism and elimination, and the formation of active metabolites. Despite the maturation of radiochemistry and molecular imaging in recent years, there has been only a handful of PET or SPECT studies of radiolabeled hallucinogens, most recently using the 5-HT2A/2C agonist N-(2[11CH3O]-methoxybenzyl)-2,5-dimethoxy- 4-bromophenethylamine ([11C]Cimbi-36). In addition to PET studies of target engagement at neuroreceptors and transporters, there is a small number of studies on the effects of hallucinogenic compounds on cerebral perfusion ([15O]-water) or metabolism ([18F]-fluorodeoxyglucose/FDG). There remains considerable scope for basic imaging research on the sites of interaction of hallucinogens and their cerebrometabolic effects; we expect that hybrid imaging with PET in conjunction with functional magnetic resonance imaging (fMRI) should provide especially useful for the next phase of this research.
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Affiliation(s)
- Paul Cumming
- Department of Nuclear Medicine, Bern University Hospital, CH-3010 Bern, Switzerland
- School of Psychology and Counselling, Queensland University of Technology, Brisbane 4059, Australia
| | - Milan Scheidegger
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, CH-8032 Zurich, Switzerland; (M.S.); (D.D.); (B.B.Q.)
| | - Dario Dornbierer
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, CH-8032 Zurich, Switzerland; (M.S.); (D.D.); (B.B.Q.)
| | - Mikael Palner
- Odense Department of Clinical Research, University of Southern Denmark, DK-5000 Odense, Denmark;
- Department of Nuclear Medicine, Odense University Hospital, DK-5000 Odense, Denmark
- Neurobiology Research Unit, Copenhagen University Hospital, DK-2100 Copenhagen, Denmark
| | - Boris B. Quednow
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, CH-8032 Zurich, Switzerland; (M.S.); (D.D.); (B.B.Q.)
- Neuroscience Center Zurich, University of Zurich and Swiss Federal Institute of Technology Zurich, CH-8058 Zurich, Switzerland
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21
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Bhat S, Guthrie DA, Kasture A, El-Kasaby A, Cao J, Bonifazi A, Ku T, Giancola JB, Hummel T, Freissmuth M, Newman AH. Tropane-Based Ibogaine Analog Rescues Folding-Deficient Serotonin and Dopamine Transporters. ACS Pharmacol Transl Sci 2021; 4:503-516. [PMID: 33860180 PMCID: PMC8033614 DOI: 10.1021/acsptsci.0c00102] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Indexed: 02/05/2023]
Abstract
![]()
Missense
mutations that give rise to protein misfolding are rare,
but collectively, defective protein folding diseases are consequential.
Folding deficiencies are amenable to pharmacological correction (pharmacochaperoning),
but the underlying mechanisms remain enigmatic. Ibogaine and its active
metabolite noribogaine correct folding defects in the dopamine transporter
(DAT), but they rescue only a very limited number of folding-deficient
DAT mutant proteins, which give rise to infantile Parkinsonism and
dystonia. Herein, a series of analogs was generated by reconfiguring
the complex ibogaine ring system and exploring the structural requirements
for binding to wild-type transporters, as well as for rescuing two
equivalent synthetic folding-deficient mutants, SERT-PG601,602AA and DAT-PG584,585AA. The most active tropane-based
analog (9b) was also an effective pharmacochaperone in vivo in Drosophila harboring the DAT-PG584,585AA mutation and rescued 6 out of 13 disease-associated
human DAT mutant proteins in vitro. Hence, a novel
lead pharmacochaperone has been identified that demonstrates medication
development potential for patients harboring DAT mutations.
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Affiliation(s)
- Shreyas Bhat
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Waehringerstrasse 13a, Vienna 1090, Austria
| | - Daryl A Guthrie
- Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, Maryland 21224, United States
| | - Ameya Kasture
- Department of Neurobiology, University of Vienna, Vienna 1090, 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, Vienna, Waehringerstrasse 13a, Vienna 1090, Austria
| | - Jianjing Cao
- Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, Maryland 21224, United States
| | - Alessandro Bonifazi
- Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, Maryland 21224, United States
| | - Therese Ku
- Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, Maryland 21224, United States
| | - JoLynn B Giancola
- Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, Maryland 21224, United States
| | - Thomas Hummel
- Department of Neurobiology, University of Vienna, Vienna 1090, 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, Vienna, Waehringerstrasse 13a, Vienna 1090, Austria
| | - Amy Hauck Newman
- Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, Baltimore, Maryland 21224, United States
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22
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Identification by proximity labeling of novel lipidic and proteinaceous potential partners of the dopamine transporter. Cell Mol Life Sci 2021; 78:7733-7756. [PMID: 34709416 PMCID: PMC8629785 DOI: 10.1007/s00018-021-03998-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 10/07/2021] [Accepted: 10/17/2021] [Indexed: 12/05/2022]
Abstract
Dopamine (DA) transporters (DATs) are regulated by trafficking and modulatory processes that probably rely on stable and transient interactions with neighboring proteins and lipids. Using proximity-dependent biotin identification (BioID), we found novel potential partners for DAT, including several membrane proteins, such as the transmembrane chaperone 4F2hc, the proteolipid M6a and a potential membrane receptor for progesterone (PGRMC2). We also detected two cytoplasmic proteins: a component of the Cullin1-dependent ubiquitination machinery termed F-box/LRR-repeat protein 2 (FBXL2), and the enzyme inositol 5-phosphatase 2 (SHIP2). Immunoprecipitation (IP) and immunofluorescence studies confirmed either a physical association or a close spatial proximity between these proteins and DAT. M6a, SHIP2 and the Cullin1 system were shown to increase DAT activity in coexpression experiments, suggesting a functional role for their association. Deeper analysis revealed that M6a, which is enriched in neuronal protrusions (filopodia or dendritic spines), colocalized with DAT in these structures. In addition, the product of SHIP2 enzymatic activity (phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2]) was tightly associated with DAT, as shown by co-IP and by colocalization of mCherry-DAT with a specific biosensor for this phospholipid. PI(3,4)P2 strongly stimulated transport activity in electrophysiological recordings, and conversely, inhibition of SHIP2 reduced DA uptake in several experimental systems including striatal synaptosomes and the dopaminergic cell line SH-SY5Y. In summary, here we report several potential new partners for DAT and a novel regulatory lipid, which may represent new pharmacological targets for DAT, a pivotal protein in dopaminergic function of the brain.
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23
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Bhat S, El-Kasaby A, Freissmuth M, Sucic S. Functional and Biochemical Consequences of Disease Variants in Neurotransmitter Transporters: A Special Emphasis on Folding and Trafficking Deficits. Pharmacol Ther 2020; 222:107785. [PMID: 33310157 PMCID: PMC7612411 DOI: 10.1016/j.pharmthera.2020.107785] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 12/02/2020] [Indexed: 01/30/2023]
Abstract
Neurotransmitters, such as γ-aminobutyric acid, glutamate, acetyl choline, glycine and the monoamines, facilitate the crosstalk within the central nervous system. The designated neurotransmitter transporters (NTTs) both release and take up neurotransmitters to and from the synaptic cleft. NTT dysfunction can lead to severe pathophysiological consequences, e.g. epilepsy, intellectual disability, or Parkinson’s disease. Genetic point mutations in NTTs have recently been associated with the onset of various neurological disorders. Some of these mutations trigger folding defects in the NTT proteins. Correct folding is a prerequisite for the export of NTTs from the endoplasmic reticulum (ER) and the subsequent trafficking to their pertinent site of action, typically at the plasma membrane. Recent studies have uncovered some of the key features in the molecular machinery responsible for transporter protein folding, e.g., the role of heat shock proteins in fine-tuning the ER quality control mechanisms in cells. The therapeutic significance of understanding these events is apparent from the rising number of reports, which directly link different pathological conditions to NTT misfolding. For instance, folding-deficient variants of the human transporters for dopamine or GABA lead to infantile parkinsonism/dystonia and epilepsy, respectively. From a therapeutic point of view, some folding-deficient NTTs are amenable to functional rescue by small molecules, known as chemical and pharmacological chaperones.
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Affiliation(s)
- Shreyas Bhat
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Ali El-Kasaby
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria.
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24
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Farr CV, El-Kasaby A, Freissmuth M, Sucic S. The Creatine Transporter Unfolded: A Knotty Premise in the Cerebral Creatine Deficiency Syndrome. Front Synaptic Neurosci 2020; 12:588954. [PMID: 33192443 PMCID: PMC7644880 DOI: 10.3389/fnsyn.2020.588954] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 09/18/2020] [Indexed: 12/16/2022] Open
Abstract
Creatine provides cells with high-energy phosphates for the rapid reconstitution of hydrolyzed adenosine triphosphate. The eponymous creatine transporter (CRT1/SLC6A8) belongs to a family of solute carrier 6 (SLC6) proteins. The key role of CRT1 is to translocate creatine across tissue barriers and into target cells, such as neurons and myocytes. Individuals harboring mutations in the coding sequence of the human CRT1 gene develop creatine transporter deficiency (CTD), one of the pivotal underlying causes of cerebral creatine deficiency syndrome. CTD encompasses an array of clinical manifestations, including severe intellectual disability, epilepsy, autism, development delay, and motor dysfunction. CTD is characterized by the absence of cerebral creatine, which implies an indispensable role for CRT1 in supplying the brain cells with creatine. CTD-associated variants dramatically reduce or abolish creatine transport activity by CRT1. Many of these are point mutations that are known to trigger folding defects, leading to the retention of encoded CRT1 proteins in the endoplasmic reticulum and precluding their delivery to the cell surface. Misfolding of several related SLC6 transporters also gives rise to detrimental pathologic conditions in people; e.g., mutations in the dopamine transporter induce infantile parkinsonism/dystonia, while mutations in the GABA transporter 1 cause treatment-resistant epilepsy. In some cases, folding defects are amenable to rescue by small molecules, known as pharmacological and chemical chaperones, which restore the cell surface expression and transport activity of the previously non-functional proteins. Insights from the recent molecular, animal and human case studies of CTD add toward our understanding of this complex disorder and reveal the wide-ranging effects elicited upon CRT1 dysfunction. This grants novel therapeutic prospects for the treatment of patients afflicted with CTD, e.g., modifying the creatine molecule to facilitate CRT1-independent entry into brain cells, or correcting folding-deficient and loss-of-function CTD variants using pharmacochaperones and/or allosteric modulators. The latter justifies a search for additional compounds with a capacity to correct mutation-specific defects.
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Affiliation(s)
| | | | | | - Sonja Sucic
- Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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25
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Abnormal Behavior of Zebrafish Mutant in Dopamine Transporter Is Rescued by Clozapine. iScience 2019; 17:325-333. [PMID: 31325771 PMCID: PMC6642228 DOI: 10.1016/j.isci.2019.06.039] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/17/2019] [Accepted: 06/28/2019] [Indexed: 11/23/2022] Open
Abstract
Dopamine transporter (SLC6A3) deficiency causes infantile Parkinson disease, for which there is no effective therapy. We have explored the effects of genetically deleting SLC6A3 in zebrafish. Unlike the wild-type, slc6a3−/− fish hover near the tank bottom, with a repetitive digging-like behavior. slc6a3−/− fish manifest pruning and cellular loss of particular tyrosine hydroxylase-immunoreactive neurons in the midbrain. Clozapine, an effective therapeutic for treatment-resistant schizophrenia, rescues the abnormal behavior of slc6a3−/− fish. Clozapine also reverses the abnormalities in the A8 region of the mutant midbrain. By RNA sequencing analysis, clozapine increases the expression of erythropoietin pathway genes. Transgenic over-expression of erythropoietin in neurons of slc6a3−/− fish partially rescues the mutant behavior, suggesting a potential mechanistic basis for clozapine's efficacy. DAT mutation in zebrafish causes digging behavior and loss of specific midbrain neurons Clozapine restores normal behavior and neuronal morphology of mutant fish Clozapine increases expression of erythropoietin pathway genes Transgenic expression of erythropoietin partially rescues the mutant behavior
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26
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Marinko J, Huang H, Penn WD, Capra JA, Schlebach JP, Sanders CR. Folding and Misfolding of Human Membrane Proteins in Health and Disease: From Single Molecules to Cellular Proteostasis. Chem Rev 2019; 119:5537-5606. [PMID: 30608666 PMCID: PMC6506414 DOI: 10.1021/acs.chemrev.8b00532] [Citation(s) in RCA: 153] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Indexed: 12/13/2022]
Abstract
Advances over the past 25 years have revealed much about how the structural properties of membranes and associated proteins are linked to the thermodynamics and kinetics of membrane protein (MP) folding. At the same time biochemical progress has outlined how cellular proteostasis networks mediate MP folding and manage misfolding in the cell. When combined with results from genomic sequencing, these studies have established paradigms for how MP folding and misfolding are linked to the molecular etiologies of a variety of diseases. This emerging framework has paved the way for the development of a new class of small molecule "pharmacological chaperones" that bind to and stabilize misfolded MP variants, some of which are now in clinical use. In this review, we comprehensively outline current perspectives on the folding and misfolding of integral MPs as well as the mechanisms of cellular MP quality control. Based on these perspectives, we highlight new opportunities for innovations that bridge our molecular understanding of the energetics of MP folding with the nuanced complexity of biological systems. Given the many linkages between MP misfolding and human disease, we also examine some of the exciting opportunities to leverage these advances to address emerging challenges in the development of therapeutics and precision medicine.
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Affiliation(s)
- Justin
T. Marinko
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Hui Huang
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Wesley D. Penn
- Department
of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - John A. Capra
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
- Department
of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37245, United States
| | - Jonathan P. Schlebach
- Department
of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Charles R. Sanders
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
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27
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How to rescue misfolded SERT, DAT and NET: targeting conformational intermediates with atypical inhibitors and partial releasers. Biochem Soc Trans 2019; 47:861-874. [PMID: 31064865 PMCID: PMC6599159 DOI: 10.1042/bst20180512] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 04/12/2019] [Accepted: 04/12/2019] [Indexed: 11/17/2022]
Abstract
Point mutations in the coding sequence for solute carrier 6 (SLC6) family members result in clinically relevant disorders, which are often accounted for by a loss-of-function phenotype. In many instances, the mutated transporter is not delivered to the cell surface because it is retained in the endoplasmic reticulum (ER). The underlying defect is improper folding of the transporter and is the case for many of the known dopamine transporter mutants. The monoamine transporters, i.e. the transporters for norepinephrine (NET/SLC6A2), dopamine (DAT/SLC6A3) and serotonin (SERT/SLC6A4), have a rich pharmacology; hence, their folding-deficient mutants lend themselves to explore the concept of pharmacological chaperoning. Pharmacochaperones are small molecules, which bind to folding intermediates with exquisite specificity and scaffold them to a folded state, which is exported from the ER and delivered to the cell surface. Pharmacochaperoning of mutant monoamine transporters, however, is not straightforward: ionic conditions within the ER are not conducive to binding of most typical monoamine transporter ligands. A collection of compounds exists, which are classified as atypical ligands because they trap monoamine transporters in unique conformational states. The atypical binding mode of some DAT inhibitors has been linked to their anti-addictive action. Here, we propose that atypical ligands and also compounds recently classified as partial releasers can serve as pharmacochaperones.
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28
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Enogieru OJ, Ung PMU, Yee SW, Schlessinger A, Giacomini KM. Functional and structural analysis of rare SLC2A2 variants associated with Fanconi-Bickel syndrome and metabolic traits. Hum Mutat 2019; 40:983-995. [PMID: 30950137 DOI: 10.1002/humu.23758] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 03/01/2019] [Accepted: 03/23/2019] [Indexed: 02/06/2023]
Abstract
Deleterious variants in SLC2A2 cause Fanconi-Bickel Syndrome (FBS), a glycogen storage disorder, whereas less common variants in SLC2A2 associate with numerous metabolic diseases. Phenotypic heterogeneity in FBS has been observed, but its causes remain unknown. Our goal was to functionally characterize rare SLC2A2 variants found in FBS and metabolic disease-associated variants to understand the impact of these variants on GLUT2 activity and expression and establish genotype-phenotype correlations. Complementary RNA-injected Xenopus laevis oocytes were used to study mutant transporter activity and membrane expression. GLUT2 homology models were constructed for mutation analysis using GLUT1, GLUT3, and XylE as templates. Seventeen FBS variants were characterized. Only c.457_462delCTTATA (p.Leu153_Ile154del) exhibited residual glucose uptake. Functional characterization revealed that only half of the variants were expressed on the plasma membrane. Most less common variants (except c.593 C>A (p.Thr198Lys) and c.1087 G>T (p.Ala363Ser)) exhibited similar GLUT2 transport activity as the wild type. Structural analysis of GLUT2 revealed that variants affect substrate-binding, steric hindrance, or overall transporter structure. The mutant transporter that is associated with a milder FBS phenotype, p.Leu153_Ile154del, retained transport activity. These results improve our overall understanding of the underlying causes of FBS and impact of GLUT2 function on various clinical phenotypes ranging from rare to common disease.
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Affiliation(s)
- Osatohanmwen J Enogieru
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California
| | - Peter M U Ung
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Sook Wah Yee
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California
| | - Avner Schlessinger
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Kathleen M Giacomini
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California.,Institute for Human Genetics, University of California, San Francisco, San Francisco, California
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Rescue by 4-phenylbutyrate of several misfolded creatine transporter-1 variants linked to the creatine transporter deficiency syndrome. Neuropharmacology 2019; 161:107572. [PMID: 30885608 DOI: 10.1016/j.neuropharm.2019.03.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 03/07/2019] [Accepted: 03/11/2019] [Indexed: 12/15/2022]
Abstract
Diseases arising from misfolding of SLC6 transporters have been reported over recent years, e.g. folding-deficient mutants of the dopamine transporter and of the glycine transporter-2 cause infantile/juvenile Parkinsonism dystonia and hyperekplexia, respectively. Mutations in the coding sequence of the human creatine transporter-1 (hCRT-1/SLC6A8) gene result in a creatine transporter deficiency syndrome, which varies in its clinical manifestation from epilepsy, mental retardation, autism, development delay and motor dysfunction to gastrointestinal symptoms. Some of the mutations in hCRT-1 occur at residues, which are highly conserved across the SLC6 family. Here, we examined 16 clinically relevant hCRT-1 variants to verify the conjecture that they were misfolded and that this folding defect was amenable to correction. Confocal microscopy imaging revealed that the heterologously expressed YFP-tagged mutant CRTs were trapped in the endoplasmic reticulum (ER), co-localised with the ER-resident chaperone calnexin. In contrast, the wild type hCRT-1 reached the plasma membrane. Preincubation of transiently transfected HEK293 cells with the chemical chaperone 4-phenylbutyrate (4-PBA) restored ER export and surface expression of as well as substrate uptake by several folding-deficient CRT-1 mutants. A representative mutant (hCRT-1-P544L) was expressed in rat primary hippocampal neurons to verify pharmacochaperoning in a target cell: 4-PBA promoted the delivery of hCRT-1-P544L to the neurite extensions. These observations show that several folding-deficient hCRT-1 mutants can be rescued. This proof-of-principle justifies the search for additional pharmacochaperones to restore folding of 4PBA-unresponsive hCRT-1 mutants. Finally, 4-PBA is an approved drug in paediatric use: this provides a rationale for translating the current insights into clinical trials. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Kasture AS, Bartel D, Steinkellner T, Sucic S, Hummel T, Freissmuth M. Distinct contribution of axonal and somatodendritic serotonin transporters in drosophila olfaction. Neuropharmacology 2019; 161:107564. [PMID: 30851308 DOI: 10.1016/j.neuropharm.2019.03.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 02/11/2019] [Accepted: 03/03/2019] [Indexed: 01/07/2023]
Abstract
The serotonin transporter (SERT) regulates serotonergic neurotransmission by retrieving released serotonin and replenishing vesicular stores. SERT is not only delivered to axons but it is also present on the neuronal soma and on dendrites. It has not been possible to restrict the distribution of SERT without affecting transporter function. Hence, the physiological role of somatodendritic SERT remains enigmatic. The SERT C-terminus harbors a conserved RI-motif, which recruits SEC24C, a cargo receptor in the coatomer protein-II coat. Failure to engage SEC24C precludes axonal enrichment of SERT. Here we introduced a point mutation into the RI-motif of human SERT causing confinement of the resulting - otherwise fully functional - hSERT-R607A on the somatodendritic membrane of primary rat dorsal raphe neurons. Transgenic expression of the corresponding Drosophila mutant dSERT-R599A led to its enrichment in the somatodendritic compartment of serotonergic neurons in the fly brain. We explored the possible physiological role of somatodendritic SERT by comparing flies harboring wild type SERT and dSERT-R599A in a behavioral paradigm for serotonin-modulated odor perception. When globally re-expressed in serotonergic neurons, wild type SERT but not dSERT-R599A restored ethanol preference. In contrast, dSERT-R599A restored ethanol preference after targeted expression in contralaterally projecting, serotonin-immunoreactive deuterocerebral (CSD) interneurons, while expression of wild type SERT caused ethanol aversion. We conclude that, in CSD neurons, (i) somatodendritic SERT supports ethanol attraction, (ii) axonal SERT specifies ethanol aversion, (iii) the effect of axonal SERT can override that of somatodendritic SERT. These observations demonstrate a distinct biological role of somatodendritic and axonal serotonin transport. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Affiliation(s)
- Ameya Sanjay Kasture
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria; Department of Neurobiology, University of Vienna, A-1090 Vienna, Austria
| | - Daniela Bartel
- Department of Neurobiology, University of Vienna, A-1090 Vienna, Austria
| | - Thomas Steinkellner
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Thomas Hummel
- Department of Neurobiology, University of Vienna, A-1090 Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria.
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Marton S, González B, Rodríguez-Bottero S, Miquel E, Martínez-Palma L, Pazos M, Prieto JP, Rodríguez P, Sames D, Seoane G, Scorza C, Cassina P, Carrera I. Ibogaine Administration Modifies GDNF and BDNF Expression in Brain Regions Involved in Mesocorticolimbic and Nigral Dopaminergic Circuits. Front Pharmacol 2019; 10:193. [PMID: 30890941 PMCID: PMC6411846 DOI: 10.3389/fphar.2019.00193] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 02/14/2019] [Indexed: 01/07/2023] Open
Abstract
Ibogaine is an atypical psychedelic alkaloid, which has been subject of research due to its reported ability to attenuate drug-seeking behavior. Recent work has suggested that ibogaine effects on alcohol self-administration in rats are related to the release of Glial cell Derived Neurotrophic Factor (GDNF) in the Ventral Tegmental Area (VTA), a mesencephalic region which hosts the soma of dopaminergic neurons. Although previous reports have shown ibogaine’s ability to induce GDNF expression in rat midbrain, there are no studies addressing its effect on the expression of GDNF and other neurotrophic factors (NFs) such as Brain Derived Neurotrophic Factor (BDNF) or Nerve Growth Factor (NGF) in distinct brain regions containing dopaminergic neurons. In this work, we examined the effect of ibogaine acute administration on the expression of these NFs in the VTA, Prefrontal Cortex (PFC), Nucleus Accumbens (NAcc) and the Substantia Nigra (SN). Rats were i.p. treated with ibogaine 20 mg/kg (I20), 40 mg/kg (I40) or vehicle, and NFs expression was analyzed after 3 and 24 h. At 24 h an increase of the expression of the NFs transcripts was observed in a site and dose dependent manner. Only for I40, GDNF was selectively upregulated in the VTA and SN. Both doses elicited a large increase in the expression of BDNF transcripts in the NAcc, SN and PFC, while in the VTA a significant effect was found only for I40. Finally, NGF mRNA was upregulated in all regions after I40, while I20 showed a selective upregulation in PFC and VTA. Regarding protein levels, an increase of GDNF was observed in the VTA only for I40 but no significant increase for BDNF was found in all the studied areas. Interestingly, an increase of proBDNF was detected in the NAcc for both doses. These results show for the first time a selective increase of GDNF specifically in the VTA for I40 but not for I20 after 24 h of administration, which agrees with the effective dose found in previous self-administration studies in rodents. Further research is needed to understand the contribution of these changes to ibogaine’s ability to attenuate drug-seeking behavior.
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Affiliation(s)
- Soledad Marton
- Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Bruno González
- Laboratorio de Síntesis Orgánica, Departamento de Química Orgánica, Facultad de Química, Universidad de la República, Montevideo, Uruguay
| | - Sebastián Rodríguez-Bottero
- Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Ernesto Miquel
- Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Laura Martínez-Palma
- Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Mariana Pazos
- Laboratorio de Síntesis Orgánica, Departamento de Química Orgánica, Facultad de Química, Universidad de la República, Montevideo, Uruguay
| | - José Pedro Prieto
- Departamento de Neurofarmacología Experimental, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - Paola Rodríguez
- Laboratorio de Síntesis Orgánica, Departamento de Química Orgánica, Facultad de Química, Universidad de la República, Montevideo, Uruguay
| | - Dalibor Sames
- Department of Chemistry, Columbia University, New York, NY, United States
| | - Gustavo Seoane
- Laboratorio de Síntesis Orgánica, Departamento de Química Orgánica, Facultad de Química, Universidad de la República, Montevideo, Uruguay
| | - Cecilia Scorza
- Departamento de Neurofarmacología Experimental, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - Patricia Cassina
- Departamento de Histología y Embriología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Ignacio Carrera
- Laboratorio de Síntesis Orgánica, Departamento de Química Orgánica, Facultad de Química, Universidad de la República, Montevideo, Uruguay
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Wasko MJ, Witt-Enderby PA, Surratt CK. DARK Classics in Chemical Neuroscience: Ibogaine. ACS Chem Neurosci 2018; 9:2475-2483. [PMID: 30216039 DOI: 10.1021/acschemneuro.8b00294] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The West African iboga plant has been used for centuries by the Bwiti and Mbiri tribes to induce hallucinations during religious ceremonies. Ibogaine, the principal alkaloid responsible for iboga's psychedelic properties, was isolated and sold as an antidepressant in France for decades before its adverse effects precipitated its removal from the market. An ibogaine resurgence in the 1960s was driven by U.S. heroin addicts who claimed that ibogaine cured their opiate addictions. Behavioral pharmacologic studies in animal models provided evidence that ibogaine could blunt self-administration of not only opiates but cocaine, amphetamines, and nicotine. Ibogaine displays moderate-to-weak affinities for a wide spectrum of receptor and transporter proteins; recent work suggests that its actions at nicotinic acetylcholine receptor subtypes may underlie its reputed antiopiate effects. At micromolar levels, ibogaine is neurotoxic and cardiotoxic and has been linked to several deaths by cardiac arrest. Structure-activity studies led to the isolation of the ibogaine analog 18-methoxycoronaridine (18-MC), an α3β4 nicotinic receptor modulator that retains ibogaine's anticraving properties with few or no adverse effects. Clinical trials of 18-MC treatment of nicotine addiction are pending. Ibogaine analogs may also hold promise for treating anxiety and depression via the "psychedelic-assisted therapy" approach that employs hallucinogens including psilocybin and methylenedioxymethamphetamine ("ecstasy").
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Affiliation(s)
- Michael J. Wasko
- Division of Pharmaceutical, Administrative and Social Sciences, Duquesne University School of Pharmacy, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, United States
| | - Paula A. Witt-Enderby
- Division of Pharmaceutical, Administrative and Social Sciences, Duquesne University School of Pharmacy, 600 Forbes Avenue, Pittsburgh, Pennsylvania 15282, United States
| | - Christopher K. Surratt
- Arnold & Marie Schwartz College of Pharmacy and Health Sciences, Long Island University−Brooklyn, 75 DeKalb Avenue, Brooklyn, New York 11201, United States
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Big Lessons from Tiny Flies: Drosophila melanogaster as a Model to Explore Dysfunction of Dopaminergic and Serotonergic Neurotransmitter Systems. Int J Mol Sci 2018; 19:ijms19061788. [PMID: 29914172 PMCID: PMC6032372 DOI: 10.3390/ijms19061788] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 06/11/2018] [Accepted: 06/13/2018] [Indexed: 12/31/2022] Open
Abstract
The brain of Drosophila melanogaster is comprised of some 100,000 neurons, 127 and 80 of which are dopaminergic and serotonergic, respectively. Their activity regulates behavioral functions equivalent to those in mammals, e.g., motor activity, reward and aversion, memory formation, feeding, sexual appetite, etc. Mammalian dopaminergic and serotonergic neurons are known to be heterogeneous. They differ in their projections and in their gene expression profile. A sophisticated genetic tool box is available, which allows for targeting virtually any gene with amazing precision in Drosophila melanogaster. Similarly, Drosophila genes can be replaced by their human orthologs including disease-associated alleles. Finally, genetic manipulation can be restricted to single fly neurons. This has allowed for addressing the role of individual neurons in circuits, which determine attraction and aversion, sleep and arousal, odor preference, etc. Flies harboring mutated human orthologs provide models which can be interrogated to understand the effect of the mutant protein on cell fate and neuronal connectivity. These models are also useful for proof-of-concept studies to examine the corrective action of therapeutic strategies. Finally, experiments in Drosophila can be readily scaled up to an extent, which allows for drug screening with reasonably high throughput.
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Identification and characterization of the Fasciola hepatica sodium- and chloride-dependent taurine transporter. PLoS Negl Trop Dis 2018; 12:e0006428. [PMID: 29702654 PMCID: PMC5942844 DOI: 10.1371/journal.pntd.0006428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 05/09/2018] [Accepted: 04/03/2018] [Indexed: 01/06/2023] Open
Abstract
The parasitic liver fluke Fasciola hepatica infests mainly ruminants, but it can also cause fasciolosis in people, who ingest the metacercariae encysted on plants. The drug of choice to treat fasciolosis is triclabendazole (TBZ), which has been on the market for several decades. This is also true for the other available drugs. Accordingly, drug-resistant flukes have been emerging at an increasing rate making it desirable to identify alternative drug targets. Here, we focused on the fact that adult F. hepatica persists in the hostile environment of the bile ducts of infected organisms. A common way to render bile acids less toxic is to conjugate them to taurine (2-aminoethanesulfonic acid). We cloned a transporter from the solute carrier-6 (SLC6) family, which was most closely related to the GABA-transporter-2 of other organisms. When heterologously expressed, this F. hepatica transporter supported the high-affinity cellular uptake of taurine (KM = 12.0 ± 0.5 μM) but not of GABA. Substrate uptake was dependent on Na+- and Cl- (calculated stoichiometry 2:1). Consistent with the low chloride concentration in mammalian bile, the F. hepatica transporter had a higher apparent affinity for Cl- (EC50 = 14±3 mM) than the human taurine transporter (EC50 = 55±7 mM). We incubated flukes with unconjugated bile acids in the presence and absence of taurine: taurine promoted survival of flukes; the taurine transporter inhibitor guanidinoethansulfonic acid abolished this protective effect of taurine. Based on these observations, we conclude that the taurine transporter is critical for the survival of liver flukes in the bile. Thus, the taurine transporter represents a candidate drug target.
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Asjad HMM, Nasrollahi-Shirazi S, Sucic S, Freissmuth M, Nanoff C. Relax, Cool Down and Scaffold: How to Restore Surface Expression of Folding-Deficient Mutant GPCRs and SLC6 Transporters. Int J Mol Sci 2017; 18:ijms18112416. [PMID: 29135937 PMCID: PMC5713384 DOI: 10.3390/ijms18112416] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 11/11/2017] [Accepted: 11/12/2017] [Indexed: 01/01/2023] Open
Abstract
Many diseases arise from mutations, which impair protein folding. The study of folding-deficient variants of G protein-coupled receptors and solute carrier 6 (SLC6) transporters has shed light on the folding trajectory, how it is monitored and how misfolding can be remedied. Reducing the temperature lowers the energy barrier between folding intermediates and thereby eliminates stalling along the folding trajectory. For obvious reasons, cooling down is not a therapeutic option. One approach to rescue misfolded variants is to use membrane-permeable orthosteric ligands. Antagonists of GPCRs are—in many instances—effective pharmacochaperones: they restore cell surface expression provided that they enter cells and bind to folding intermediates. Pharmacochaperoning of SLC6 transporters is less readily achieved because the ionic conditions in the endoplasmic reticulum (ER) are not conducive to binding of typical inhibitors. The second approach is to target the heat-shock protein (HSP) relay, which monitors the folding trajectory on the cytosolic side. Importantly, orthosteric ligands and HSP-inhibitors are not mutually exclusive. In fact, pharmacochaperones and HSP-inhibitors can act in an additive or synergistic manner. This was exemplified by rescuing disease-causing, folding-deficient variants of the human dopamine transporters with the HSP70 inhibitor pifithrin-μ and the pharmacochaperone noribogaine in Drosophila melanogaster.
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Affiliation(s)
- H M Mazhar Asjad
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria.
| | - Shahrooz Nasrollahi-Shirazi
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria.
| | - Sonja Sucic
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria.
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria.
| | - Christian Nanoff
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria.
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