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Huang N, Winans T, Wyman B, Oaks Z, Faludi T, Choudhary G, Lai ZW, Lewis J, Beckford M, Duarte M, Krakko D, Patel A, Park J, Caza T, Sadeghzadeh M, Morel L, Haas M, Middleton F, Banki K, Perl A. Rab4A-directed endosome traffic shapes pro-inflammatory mitochondrial metabolism in T cells via mitophagy, CD98 expression, and kynurenine-sensitive mTOR activation. Nat Commun 2024; 15:2598. [PMID: 38519468 PMCID: PMC10960037 DOI: 10.1038/s41467-024-46441-2] [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: 02/23/2023] [Accepted: 02/28/2024] [Indexed: 03/25/2024] Open
Abstract
Activation of the mechanistic target of rapamycin (mTOR) is a key metabolic checkpoint of pro-inflammatory T-cell development that contributes to the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus (SLE), however, the underlying mechanisms remain poorly understood. Here, we identify a functional role for Rab4A-directed endosome traffic in CD98 receptor recycling, mTOR activation, and accumulation of mitochondria that connect metabolic pathways with immune cell lineage development and lupus pathogenesis. Based on integrated analyses of gene expression, receptor traffic, and stable isotope tracing of metabolic pathways, constitutively active Rab4AQ72L exerts cell type-specific control over metabolic networks, dominantly impacting CD98-dependent kynurenine production, mTOR activation, mitochondrial electron transport and flux through the tricarboxylic acid cycle and thus expands CD4+ and CD3+CD4-CD8- double-negative T cells over CD8+ T cells, enhancing B cell activation, plasma cell development, antinuclear and antiphospholipid autoantibody production, and glomerulonephritis in lupus-prone mice. Rab4A deletion in T cells and pharmacological mTOR blockade restrain CD98 expression, mitochondrial metabolism and lineage skewing and attenuate glomerulonephritis. This study identifies Rab4A-directed endosome traffic as a multilevel regulator of T cell lineage specification during lupus pathogenesis.
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Affiliation(s)
- Nick Huang
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
- Department of Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Thomas Winans
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
- Department of Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Brandon Wyman
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
- Department of Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Zachary Oaks
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
- Department of Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Tamas Faludi
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Gourav Choudhary
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
- Department of Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Zhi-Wei Lai
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Joshua Lewis
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Miguel Beckford
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Manuel Duarte
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Daniel Krakko
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Akshay Patel
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
- Department of Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Joy Park
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
- Department of Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Tiffany Caza
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Mahsa Sadeghzadeh
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
- Department of Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Laurence Morel
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - Mark Haas
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, 90048, USA
| | - Frank Middleton
- Department of Neuroscience and Physiology, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Katalin Banki
- Department of Pathology, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA
| | - Andras Perl
- Department of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA.
- Department of Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA.
- Department of Microbiology and Immunology, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York, NY, 13210, USA.
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2
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Camacho-Hernandez GA, Jahan K, Newman AH. Illuminating the monoamine transporters: Fluorescently labelled ligands to study dopamine, serotonin and norepinephrine transporters. Basic Clin Pharmacol Toxicol 2023; 133:473-484. [PMID: 36527444 PMCID: PMC11309735 DOI: 10.1111/bcpt.13827] [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: 10/11/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022]
Abstract
Fluorescence microscopy has revolutionized the visualization of physiological processes in live-cell systems. With the recent innovations in super resolution microscopy, these events can be examined with high precision and accuracy. The development of fluorescently labelled small molecules has provided a significant advance in understanding the physiological relevance of targeted proteins that can now be visualized at the cellular level. One set of physiologically important target proteins are the monoamine transporters (MATs) that play an instrumental role in maintaining monoamine signalling homeostasis. Understanding the mechanisms underlying their regulation and dysregulation is fundamental to treating several neuropsychiatric conditions such as attention deficit hyperactivity disorder (ADHD), anxiety, depression and substance use disorders. Herein, we describe the rationale behind the small molecule design of fluorescently labelled ligands (FLL) either as MAT substrates or inhibitors as well as their applications to advance our understanding of this class of transporters in health and disease.
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Affiliation(s)
- Gisela Andrea Camacho-Hernandez
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes on Drug Abuse - Intramural Research Program, Baltimore, Maryland, USA
| | - Khorshada Jahan
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes on Drug Abuse - Intramural Research Program, Baltimore, Maryland, USA
| | - Amy Hauck Newman
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes on Drug Abuse - Intramural Research Program, Baltimore, Maryland, USA
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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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Braccagni G, Scheggi S, Bortolato M. Elevated levels of serotonin 5-HT 2A receptors in the orbitofrontal cortex of antisocial individuals. Eur Arch Psychiatry Clin Neurosci 2023; 273:411-425. [PMID: 36094569 PMCID: PMC10831872 DOI: 10.1007/s00406-022-01480-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 08/17/2022] [Indexed: 11/03/2022]
Abstract
Antisocial behavior (ASB) is characterized by frequent violations of the rights and properties of others, as well as aggressive conduct. While ample evidence points to a critical role of serotonin in the emotional modulation of social responses, the implication of this neurotransmitter in ASB is unclear. Here, we performed the first-ever postmortem analysis of serotonergic markers in the orbitofrontal cortex (OFC) of male subjects with ASB (n = 9). We focused on this brain region, given its well-recognized role in social response and ASB pathophysiology. Given that all individuals also had a substance use disorder (SUD) diagnosis, two age-matched control groups were used: SUD only and unaffected controls. Tissues were processed for immunoblotting analyses on eight key serotonergic targets: tryptophan hydroxylase 2 (TPH2), the rate-limiting enzyme of brain serotonin synthesis; serotonin transporter (SERT), the primary carrier for serotonin uptake; monoamine oxidase A (MAOA), the primary enzyme for serotonin catabolism; and five serotonin receptors previously shown to influence social behavior: 5-HT1A, 5-HT1B, 5-HT2A, 5-HT2C, and 5-HT4. Our analyses documented a significant increase in 5-HT2A receptor levels in the ASB + SUD group compared to SUD-only controls. Furthermore, TPH2 levels were significantly reduced in the SUD group (including SUD only and ASB + SUD) compared to unaffected controls. No difference was detected in the expression of any other serotonergic target. These results are in keeping with previous evidence showing high 5-HT2A receptor binding in the OFC of pathologically aggressive individuals and point to this molecule as a potential target for ASB treatment.
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Affiliation(s)
- Giulia Braccagni
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, L.S. Skaggs Hall, Room 3916, 30 S 2000 E, Salt Lake City, UT, 84112, USA
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Simona Scheggi
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Marco Bortolato
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, L.S. Skaggs Hall, Room 3916, 30 S 2000 E, Salt Lake City, UT, 84112, USA.
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5
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Deo N, Redpath G. Serotonin Receptor and Transporter Endocytosis Is an Important Factor in the Cellular Basis of Depression and Anxiety. Front Cell Neurosci 2022; 15:804592. [PMID: 35280519 PMCID: PMC8912961 DOI: 10.3389/fncel.2021.804592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 12/16/2021] [Indexed: 11/13/2022] Open
Abstract
Depression and anxiety are common, debilitating psychiatric conditions affecting millions of people throughout the world. Current treatments revolve around selective serotonin reuptake inhibitors (SSRIs), yet these drugs are only moderately effective at relieving depression. Moreover, up to 30% of sufferers are SSRI non-responders. Endocytosis, the process by which plasma membrane and extracellular constituents are internalized into the cell, plays a central role in the regulation of serotonin (5-hydroxytryptophan, 5-HT) signaling, SSRI function and depression and anxiety pathogenesis. Despite their therapeutic potential, surprisingly little is known about the endocytosis of the serotonin receptors (5-HT receptors) or the serotonin transporter (SERT). A subset of 5-HT receptors are endocytosed by clathrin-mediated endocytosis following serotonin binding, while for the majority of 5-HT receptors the endocytic regulation is not known. SERT internalizes serotonin from the extracellular space into the cell to limit the availability of serotonin for receptor binding and signaling. Endocytosis of SERT reduces serotonin uptake, facilitating serotonin signaling. SSRIs predominantly inhibit SERT, preventing serotonin uptake to enhance 5-HT receptor signaling, while hallucinogenic compounds directly activate specific 5-HT receptors, altering their interaction with endocytic adaptor proteins to induce alternate signaling outcomes. Further, multiple polymorphisms and transcriptional/proteomic alterations have been linked to depression, anxiety, and SSRI non-response. In this review, we detail the endocytic regulation of 5-HT receptors and SERT and outline how SSRIs and hallucinogenic compounds modulate serotonin signaling through endocytosis. Finally, we will examine the deregulated proteomes in depression and anxiety and link these with 5-HT receptor and SERT endocytosis. Ultimately, in attempting to integrate the current studies on the cellular biology of depression and anxiety, we propose that endocytosis is an important factor in the cellular basis of depression and anxiety. We will highlight how a thorough understanding 5-HT receptor and SERT endocytosis is integral to understanding the biological basis of depression and anxiety, and to facilitate the development of a next generation of specific, efficacious antidepressant treatments.
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Affiliation(s)
- Nikita Deo
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Gregory Redpath
- European Molecular Biology Lab (EMBL) Australia Node in Single Molecule Science, School of Medical Sciences and the Australian Research Council (ARC) Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, NSW, Australia
- *Correspondence: Gregory Redpath
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6
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Tomlinson ID, Kovtun O, Torres R, Bellocchio LG, Josephs T, Rosenthal SJ. A Novel Biotinylated Homotryptamine Derivative for Quantum Dot Imaging of Serotonin Transporter in Live Cells. Front Cell Neurosci 2021; 15:667044. [PMID: 34867196 PMCID: PMC8637195 DOI: 10.3389/fncel.2021.667044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 10/19/2021] [Indexed: 11/21/2022] Open
Abstract
The serotonin transporter (SERT) is the primary target for selective serotonin reuptake inhibitor (SSRI) antidepressants that are thought to exert their therapeutic effects by increasing the synaptic concentration of serotonin. Consequently, probes that can be utilized to study cellular trafficking of SERT are valuable research tools. We have developed a novel ligand (IDT785) that is composed of a SERT antagonist (a tetrahydro pyridyl indole derivative) conjugated to a biotinylated poly ethylene glycol (PEG) via a phenethyl linker. This compound was determined to be biologically active and inhibited SERT-mediated reuptake of IDT307 with the half-maximal inhibitory concentration of 7.2 ± 0.3 μM. We demonstrated that IDT785 enabled quantum dot (QD) labeling of membrane SERT in transfected HEK-293 cultures that could be blocked using the high affinity serotonin reuptake inhibitor paroxetine. Molecular docking studies suggested that IDT785 might be binding to the extracellular vestibule binding site rather than the orthosteric substrate binding site, which could be attributable to the hydrophilicity of the PEG chain and the increased loss of degrees of freedom that would be required to penetrate into the orthosteric binding site. Using IDT785, we were able to study the membrane localization and membrane dynamics of YFP-SERT heterologously expressed in HEK-293 cells and demonstrated that SERT expression was enriched in the membrane edge and in thin cellular protrusions.
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Affiliation(s)
- Ian D. Tomlinson
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Oleg Kovtun
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Ruben Torres
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, United States
| | | | - Travis Josephs
- Neuroscience Program, Vanderbilt University, Nashville, TN, United States
| | - Sandra J. Rosenthal
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, United States
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, United States
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, TN, United States
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7
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Abbiati RA, Wientjes MG, Au JLS. Is It Time to Use Modeling of Cellular Transporter Homeostasis to Inform Drug-Drug Interaction Studies: Theoretical Considerations. AAPS J 2021; 23:102. [PMID: 34435271 PMCID: PMC11048728 DOI: 10.1208/s12248-021-00635-4] [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: 06/08/2021] [Accepted: 08/06/2021] [Indexed: 11/30/2022] Open
Abstract
Mathematical modeling has been an important tool in pharmaceutical research for 50 + years and there is increased emphasis over the last decade on using modeling to improve the efficiency and effectiveness of drug development. In an earlier commentary, we applied a multiscale model linking 6 scales (whole body, tumor, vasculature, cell, spatial location, time), together with literature data on nanoparticle and tumor properties, to demonstrate the effects of nanoparticle particles on systemic disposition. The current commentary used a 4-scale model (cell membrane, intracellular organelles, spatial location, time) together with literature data on the intracellular processing of membrane receptors and transporters to demonstrate disruption of transporter homeostasis can lead to drug-drug interaction (DDI) between victim drug (VD) and perpetrator drug (PD), including changes in the area-under-concentration-time-curve of VD in cells that are considered significant by the US Food and Drug Administration (FDA). The model comprised 3 computational components: (a) intracellular transporter homeostasis, (b) pharmacokinetics of extracellular and intracellular VD/PD concentrations, and (c) pharmacodynamics of PD-induced stimulation or inhibition of an intracellular kinetic process. Model-based simulations showed that (a) among the five major endocytic processes, perturbation of transporter internalization or recycling led to the highest incidence and most extensive DDI, with minor DDI for perturbing transporter synthesis and early-to-late endosome and no DDI for perturbing transporter degradation and (b) three experimental conditions (spatial transporter distribution in cells, VD/PD co-incubation time, extracellular PD concentrations) were determinants of DDI detection. We propose modeling is a useful tool for hypothesis generation and for designing experiments to identify potential DDI; its application further aligns with the model-informed drug development paradigm advocated by FDA.
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Affiliation(s)
- Roberto A Abbiati
- Institute of Quantitative Systems Pharmacology, Carlsbad, California, 92008, USA
- Department of Pharmaceutical Sciences, University of Oklahoma, Oklahoma City, Oklahoma, 73117, USA
| | - M Guillaume Wientjes
- Institute of Quantitative Systems Pharmacology, Carlsbad, California, 92008, USA
- Optimum Therapeutics LLC, 1815 Aston Ave, Suite 107, Carlsbad, California, 92008, USA
| | - Jessie L-S Au
- Institute of Quantitative Systems Pharmacology, Carlsbad, California, 92008, USA.
- Department of Pharmaceutical Sciences, University of Oklahoma, Oklahoma City, Oklahoma, 73117, USA.
- Optimum Therapeutics LLC, 1815 Aston Ave, Suite 107, Carlsbad, California, 92008, USA.
- Taipei Medical University, Taipei, Taiwan, Republic of China.
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8
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Camacho-Hernandez GA, Casiraghi A, Rudin D, Luethi D, Ku TC, Guthrie DA, Straniero V, Valoti E, Schütz GJ, Sitte HH, Newman AH. Illuminating the norepinephrine transporter: fluorescent probes based on nisoxetine and talopram. RSC Med Chem 2021; 12:1174-1186. [PMID: 34355183 DOI: 10.1039/d1md00072a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 05/27/2021] [Indexed: 01/30/2023] Open
Abstract
The utilization of fluorescent ligands to study the monoamine transporters (MATs) has increased our knowledge of their function and distribution in live cell systems. In this study, we extend SAR for nisoxetine and talopram as parent compounds, to identify high affinity rhodamine-labeled fluorescent probes for the norepinephrine transporter (NET). Nisoxetine-based fluorescent probe 6 demonstrated high binding affinity (K i = 43 nM) for NET and an overall selectivity compared to the other transporters for dopamine (DAT; K i = 1540 nM) and serotonin (SERT; K i = 785 nM) in competitive radioligand binding assays. Using confocal microscopy, compound 6 was shown to stain both NET and SERT, but not DAT, at low nanomolar concentrations, in transporter-expressing cells.
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Affiliation(s)
- Gisela Andrea Camacho-Hernandez
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes of Drug Abuse - Intramural Research Program Baltimore MD 21224 USA
| | - Andrea Casiraghi
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes of Drug Abuse - Intramural Research Program Baltimore MD 21224 USA .,Department of Pharmaceutical Sciences, University of Milan Via Mangiagalli 25 20133 Milan Italy
| | - Deborah Rudin
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna Waehringer Strasse 13a 1090 Vienna Austria
| | - Dino Luethi
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna Waehringer Strasse 13a 1090 Vienna Austria.,Institute of Applied Physics TU Wien, Lehárgasse 6 1060 Vienna Austria
| | - Therese C Ku
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes of Drug Abuse - Intramural Research Program Baltimore MD 21224 USA
| | - Daryl A Guthrie
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes of Drug Abuse - Intramural Research Program Baltimore MD 21224 USA
| | - Valentina Straniero
- Department of Pharmaceutical Sciences, University of Milan Via Mangiagalli 25 20133 Milan Italy
| | - Ermanno Valoti
- Department of Pharmaceutical Sciences, University of Milan Via Mangiagalli 25 20133 Milan Italy
| | - Gerhard J Schütz
- Institute of Applied Physics TU Wien, Lehárgasse 6 1060 Vienna Austria
| | - Harald H Sitte
- Institute of Pharmacology, Center for Physiology and Pharmacology, Medical University of Vienna Waehringer Strasse 13a 1090 Vienna Austria
| | - Amy Hauck Newman
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institutes of Drug Abuse - Intramural Research Program Baltimore MD 21224 USA
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9
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Ye D, Xu H, Xia H, Zhang C, Tang Q, Bi F. Targeting SERT promotes tryptophan metabolism: mechanisms and implications in colon cancer treatment. J Exp Clin Cancer Res 2021; 40:173. [PMID: 34006301 PMCID: PMC8132442 DOI: 10.1186/s13046-021-01971-1] [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: 03/29/2021] [Accepted: 05/05/2021] [Indexed: 02/08/2023] Open
Abstract
Background Serotonin signaling has been associated with tumorigenesis and tumor progression. Targeting the serotonin transporter to block serotonin cellular uptake confers antineoplastic effects in various tumors, including colon cancer. However, the antineoplastic mechanism of serotonin transporter inhibition and serotonin metabolism alterations in the absence of serotonin transporter have not been elucidated, especially in colon cancer, which might limit anti-tumor effects associating with targeting serotonin transporter. Methods The promotion in the uptake and catabolism of extracellular tryptophan and targeting serotonin transporter was detected by using quantitative reverse-transcription polymerase chain reaction, western blotting and liquid chromatography tandem mass spectrometry. Western blotting Immunoprecipitation and immunofluorescence was utilized to research the serotonylation of mTOR by serotonin and serotonin transporter inhibition. The primary mouse model, homograft model and tissue microarry was used to explore the tryptophan pathway in colon cancer. The cell viability assay, western blotting, xenograft and primary colon cancer mouse model were used to identify whether the combination of sertraline and tryptophan restriction had a synergistic effect. Results Targeting serotonin transporter through genetic ablation or pharmacological inhibition in vitro and in vivo induced a compensatory effect by promoting the uptake and catabolism of extracellular tryptophan in colon cancer. Mechanistically, targeting serotonin transporter suppressed mTOR serotonylation, leading to mTOR inactivation and increased tryptophan uptake. In turn, this process promoted serotonin biosynthesis and oncogenic metabolite kynurenine production through enhanced tryptophan catabolism. Tryptophan deprivation, or blocking its uptake by using trametinib, a MEK inhibitor, can sensitize colon cancer to selective serotonin reuptake inhibitors. Conclusions The present study elucidated a novel feedback mechanism involved in the regulation of serotonin homeostasis and suggested innovative strategies for selective serotonin reuptake inhibitors-based treatment of colon cancer. Supplementary Information The online version contains supplementary material available at 10.1186/s13046-021-01971-1.
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Affiliation(s)
- Di Ye
- Department of Medical Oncology, Cancer Center and Laboratory of Molecular, Targeted Therapy in Oncology, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan Province, China
| | - Huanji Xu
- Department of Medical Oncology, Cancer Center and Laboratory of Molecular, Targeted Therapy in Oncology, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan Province, China
| | - Hongwei Xia
- Department of Medical Oncology, Cancer Center and Laboratory of Molecular, Targeted Therapy in Oncology, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan Province, China
| | - Chenliang Zhang
- Department of Medical Oncology, Cancer Center and Laboratory of Molecular, Targeted Therapy in Oncology, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan Province, China
| | - Qiulin Tang
- Department of Medical Oncology, Cancer Center and Laboratory of Molecular, Targeted Therapy in Oncology, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan Province, China
| | - Feng Bi
- Department of Medical Oncology, Cancer Center and Laboratory of Molecular, Targeted Therapy in Oncology, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan Province, China.
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10
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Macias A, de la Cruz A, Peraza DA, de Benito-Bueno A, Gonzalez T, Valenzuela C. K V1.5-K Vβ1.3 Recycling Is PKC-Dependent. Int J Mol Sci 2021; 22:ijms22031336. [PMID: 33572906 PMCID: PMC7866247 DOI: 10.3390/ijms22031336] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/12/2021] [Accepted: 01/26/2021] [Indexed: 11/26/2022] Open
Abstract
KV1.5 channel function is modified by different regulatory subunits. KVβ1.3 subunits assemble with KV1.5 channels and induce a fast and incomplete inactivation. Inhibition of PKC abolishes the KVβ1.3-induced fast inactivation, decreases the amplitude of the current KV1.5–KVβ1.3 and modifies their pharmacology likely due to changes in the traffic of KV1.5–KVβ1.3 channels in a PKC-dependent manner. In order to analyze this hypothesis, HEK293 cells were transfected with KV1.5–KVβ1.3 channels, and currents were recorded by whole-cell configuration of the patch-clamp technique. The presence of KV1.5 in the membrane was analyzed by biotinylation techniques, live cell imaging and confocal microscopy approaches. PKC inhibition resulted in a decrease of 33 ± 7% of channels in the cell surface due to reduced recycling to the plasma membrane, as was confirmed by confocal microscopy. Live cell imaging indicated that PKC inhibition almost abolished the recycling of the KV1.5–KVβ1.3 channels, generating an accumulation of channels into the cytoplasm. All these results suggest that the trafficking regulation of KV1.5–KVβ1.3 channels is dependent on phosphorylation by PKC and, therefore, they could represent a clinically relevant issue, mainly in those diseases that exhibit modifications in PKC activity.
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Affiliation(s)
- Alvaro Macias
- Instituto de Investigaciones Biomédicas Madrid CSIC-UAM. C/Arturo Duperier 4, 28029 Madrid, Spain; (A.d.l.C.); (D.A.P.); (A.d.B.-B.); (T.G.)
- CIBER Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
- Correspondence: (A.M.); (C.V.); Tel.: +34-91-453-1200 (A.M.); +34-91-585-4493 (C.V.)
| | - Alicia de la Cruz
- Instituto de Investigaciones Biomédicas Madrid CSIC-UAM. C/Arturo Duperier 4, 28029 Madrid, Spain; (A.d.l.C.); (D.A.P.); (A.d.B.-B.); (T.G.)
| | - Diego A. Peraza
- Instituto de Investigaciones Biomédicas Madrid CSIC-UAM. C/Arturo Duperier 4, 28029 Madrid, Spain; (A.d.l.C.); (D.A.P.); (A.d.B.-B.); (T.G.)
- CIBER Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - Angela de Benito-Bueno
- Instituto de Investigaciones Biomédicas Madrid CSIC-UAM. C/Arturo Duperier 4, 28029 Madrid, Spain; (A.d.l.C.); (D.A.P.); (A.d.B.-B.); (T.G.)
- CIBER Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - Teresa Gonzalez
- Instituto de Investigaciones Biomédicas Madrid CSIC-UAM. C/Arturo Duperier 4, 28029 Madrid, Spain; (A.d.l.C.); (D.A.P.); (A.d.B.-B.); (T.G.)
- CIBER Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
- Department of Biochemistry, School of Medicine, Universidad Autónoma de Madrid, 28029 Madrid, Spain
- Instituto de Investigación Sanitaria del Hospital Universitario La Paz (IdiPAZ), 28029 Madrid, Spain
| | - Carmen Valenzuela
- Instituto de Investigaciones Biomédicas Madrid CSIC-UAM. C/Arturo Duperier 4, 28029 Madrid, Spain; (A.d.l.C.); (D.A.P.); (A.d.B.-B.); (T.G.)
- CIBER Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
- Correspondence: (A.M.); (C.V.); Tel.: +34-91-453-1200 (A.M.); +34-91-585-4493 (C.V.)
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Ragu Varman D, Jayanthi LD, Ramamoorthy S. Glycogen synthase kinase-3ß supports serotonin transporter function and trafficking in a phosphorylation-dependent manner. J Neurochem 2020; 156:445-464. [PMID: 32797733 DOI: 10.1111/jnc.15152] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 07/23/2020] [Accepted: 08/10/2020] [Indexed: 12/13/2022]
Abstract
Serotonin (5-HT) transporter (SERT) plays a crucial role in serotonergic transmission in the central nervous system, and any aberration causes serious mental illnesses. Nevertheless, the cellular mechanisms that regulate SERT function and trafficking are not entirely understood. Growing evidence suggests that several protein kinases act as modulators. Here, we delineate the molecular mechanisms by which glycogen synthase kinase-3ß (GSK3ß) regulates SERT. When mouse striatal synaptosomes were treated with the GSK3α/ß inhibitor CHIR99021, we observed a significant increase in SERT function, Vmax , surface expression with a reduction in 5-HT Km and SERT phosphorylation. To further study how the SERT molecule is affected by GSK3α/ß, we used HEK-293 cells as a heterologous expression system. As in striatal synaptosomes, CHIR99021 treatment of cells expressing wild-type hSERT (hSERT-WT) resulted in a time and dose-dependent elevation of hSERT function with a concomitant increase in the Vmax and surface transporters because of reduced internalization and enhanced membrane insertion; silencing GSK3α/ß in these cells with siRNA also similarly affected hSERT. Converting putative GSK3α/ß phosphorylation site serine at position 48 to alanine in hSERT (hSERT-S48A) completely abrogated the effects of both the inhibitor CHIR99021 and GSK3α/ß siRNA. Substantiating these findings, over-expression of constitutively active GSK3ß with hSERT-WT, but not with hSERT-S48A, reduced SERT function, Vmax , surface density, and enhanced transporter phosphorylation. Both hSERT-WT and hSERT-S48A were inhibited similarly by PKC activation or by inhibition of Akt, CaMKII, p38 MAPK, or Src kinase. These findings provide new evidence that GSK3ß supports basal SERT function and trafficking via serine-48 phosphorylation.
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Affiliation(s)
- Durairaj Ragu Varman
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Lankupalle D Jayanthi
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Sammanda Ramamoorthy
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
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12
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Salazar MD, Zelt NB, Saldivar R, Kuntz CP, Chen S, Penn WD, Bonneau R, Koehler Leman J, Schlebach JP. Classification of the Molecular Defects Associated with Pathogenic Variants of the SLC6A8 Creatine Transporter. Biochemistry 2020; 59:1367-1377. [PMID: 32207963 DOI: 10.1021/acs.biochem.9b00956] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
More than 80 loss-of-function (LOF) mutations in the SLC6A8 creatine transporter (hCRT1) are responsible for cerebral creatine deficiency syndrome (CCDS), which gives rise to a spectrum of neurological defects, including intellectual disability, epilepsy, and autism spectrum disorder. To gain insight into the nature of the molecular defects caused by these mutations, we quantitatively profiled the cellular processing, trafficking, expression, and function of eight pathogenic CCDS variants in relation to the wild type (WT) and one neutral isoform. All eight CCDS variants exhibit measurable proteostatic deficiencies that likely contribute to the observed LOF. However, the magnitudes of their specific effects on the expression and trafficking of hCRT1 vary considerably, and we find that the LOF associated with two of these variants primarily arises from the disruption of the substrate-binding pocket. In conjunction with an analysis of structural models of the transporter, we use these data to suggest mechanistic classifications for these variants. To evaluate potential avenues for therapeutic intervention, we assessed the sensitivity of these variants to temperature and measured their response to the proteostasis regulator 4-phenylbutyrate (4-PBA). Only one of the tested variants (G132V) is sensitive to temperature, though its response to 4-PBA is negligible. Nevertheless, 4-PBA significantly enhances the activity of WT hCRT1 in HEK293T cells, which suggests it may be worth evaluating as a therapeutic for female intellectual disability patients carrying a single CCDS mutation. Together, these findings reveal that pathogenic SLC6A8 mutations cause a spectrum of molecular defects that should be taken into consideration in future efforts to develop CCDS therapeutics.
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Affiliation(s)
- Martin D Salazar
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Nathan B Zelt
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Robert Saldivar
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Charles P Kuntz
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Sheng Chen
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Wesley D Penn
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Richard Bonneau
- Center for Computational Biology, Flatiron Institute, Simons Foundation, New York, New York 10010, United States.,Department of Biology, New York University, New York, New York 10003, United States.,Department of Computer Science, New York University, New York, New York 10012, United States.,Center for Data Science, New York University, New York, New York 10011, United States
| | - Julia Koehler Leman
- Center for Computational Biology, Flatiron Institute, Simons Foundation, New York, New York 10010, United States
| | - Jonathan P Schlebach
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
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13
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Gopaldas M, Zanderigo F, Zhan S, Ogden RT, Miller JM, Rubin-Falcone H, Cooper TB, Oquendo MA, Sullivan G, Mann JJ, Sublette ME. Brain serotonin transporter binding, plasma arachidonic acid and depression severity: A positron emission tomography study of major depression. J Affect Disord 2019; 257:495-503. [PMID: 31319341 PMCID: PMC6886679 DOI: 10.1016/j.jad.2019.07.035] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 06/11/2019] [Accepted: 07/04/2019] [Indexed: 11/17/2022]
Abstract
BACKGROUND Serotonin transporter (5-HTT) binding and polyunsaturated fatty acids (PUFAs) are implicated in major depressive disorder (MDD). Links between the two systems in animal models have not been investigated in humans. METHODS Using positron emission tomography (PET) and [11C]DASB, we studied relationships between 5-HTT binding potential and plasma levels of PUFAs docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (AA) in medication-free MDD patients (n = 21). PUFAs were quantified using transesterification and gas chromatography. Binding potential BPP, and alternative outcome measures BPF and BPND, were determined for [11C]DASB in six a priori brain regions of interest (ROIs) using likelihood estimation in graphical analysis (LEGA) to calculate radioligand total distribution volume (VT), and a validated hybrid deconvolution approach (HYDECA) that estimates radioligand non-displaceable distribution volume (VND) without a reference region. Linear mixed models used PUFA levels as predictors and binding potential measures as outcomes across the specified ROIs; age and sex as fixed effects; and subject as random effect to account for across-region binding correlations. As nonlinear relationships were observed, a quadratic term was added to final models. RESULTS AA predicted both 5-HTT BPP and depression severity nonlinearly, described by an inverted U-shaped curve. 5-HTT binding potential mediated the relationship between AA and depression severity. LIMITATIONS Given the small sample and multiple comparisons, results require replication. CONCLUSIONS Our findings suggest that AA status may impact depression pathophysiology through effects on serotonin transport. Future studies should examine whether these relationships explain therapeutic effects of PUFAs in the treatment of MDD.
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Affiliation(s)
- Manesh Gopaldas
- Department of Psychiatry, Columbia University, New York, NY, USA,Molecular Imaging & Neuropathology Area, New York State Psychiatric Institute, New York, NY, USA,Department of Psychiatry & Behavioral Sciences, Vanderbilt University Medical Center, Nashville, TN
| | - Francesca Zanderigo
- Department of Psychiatry, Columbia University, New York, NY, USA,Molecular Imaging & Neuropathology Area, New York State Psychiatric Institute, New York, NY, USA
| | - Serena Zhan
- Department of Biostatistics, Mailman School of Public Health, Columbia University, New York, NY
| | - R. Todd Ogden
- Department of Psychiatry, Columbia University, New York, NY, USA,Molecular Imaging & Neuropathology Area, New York State Psychiatric Institute, New York, NY, USA,Department of Biostatistics, Mailman School of Public Health, Columbia University, New York, NY
| | - Jeffrey M. Miller
- Department of Psychiatry, Columbia University, New York, NY, USA,Molecular Imaging & Neuropathology Area, New York State Psychiatric Institute, New York, NY, USA
| | - Harry Rubin-Falcone
- Department of Psychiatry, Columbia University, New York, NY, USA,Molecular Imaging & Neuropathology Area, New York State Psychiatric Institute, New York, NY, USA
| | - Thomas B. Cooper
- Department of Psychiatry, Columbia University, New York, NY, USA,Molecular Imaging & Neuropathology Area, New York State Psychiatric Institute, New York, NY, USA,Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY, USA
| | - Maria A. Oquendo
- Psychiatry Department, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | - J. John Mann
- Department of Psychiatry, Columbia University, New York, NY, USA,Molecular Imaging & Neuropathology Area, New York State Psychiatric Institute, New York, NY, USA,Department of Radiology, Columbia University, New York, NY, USA
| | - M. Elizabeth Sublette
- Department of Psychiatry, Columbia University, New York, NY, USA,Molecular Imaging & Neuropathology Area, New York State Psychiatric Institute, New York, NY, USA,To whom correspondence should be addressed: New York State Psychiatric Institute, 1051 Riverside Drive, Unit 42, New York, NY 10032, Tel: 646 774-7514, Fax: 646 774-7589,
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14
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Abstract
Cell nutrition, detoxification, signalling, homeostasis and response to drugs, processes related to cell growth, differentiation and survival are all mediated by plasma membrane (PM) proteins called transporters. Despite their distinct fine structures, mechanism of function, energetic requirements, kinetics and substrate specificities, all transporters are characterized by a main hydrophobic body embedded in the PM as a series of tightly packed, often intertwined, α-helices that traverse the lipid bilayer in a zigzag mode, connected with intracellular or extracellular loops and hydrophilic N- and C-termini. Whereas longstanding genetic, biochemical and biophysical evidence suggests that specific transmembrane segments, and also their connecting loops, are responsible for substrate recognition and transport dynamics, emerging evidence also reveals the functional importance of transporter N- and C-termini, in respect to transport catalysis, substrate specificity, subcellular expression, stability and signalling. This review highlights selected prototypic examples of transporters in which their termini play important roles in their functioning.
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Affiliation(s)
- Emmanuel Mikros
- Faculty of Pharmacy, National and Kapodistrian University of Athens, Panepistimioupolis, 15771 Athens, Greece
| | - George Diallinas
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, 15781 Athens, Greece
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15
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He Y, Suofu Y, Yablonska S, Wang X, Larkin TM, Kim J, Carlisle DL, Friedlander RM. Increased Serotonin Transporter Expression in Huntington's Disease Patients Is Not Consistently Replicated in Murine Models. J Huntingtons Dis 2019; 8:449-457. [PMID: 31594239 DOI: 10.3233/jhd-180318] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Selective serotonin reuptake inhibitors (SSRIs) target the serotonin transporter (SERT) and are commonly prescribed for depression in Huntington's disease (HD) patients. However, SERT expression in HD has not been carefully evaluated in patients or mouse models. OBJECTIVE In this study, we investigated SERT levels in HD patients and HD mouse models. METHODS We obtained HD patient brain striatal samples and matched controls, as well as brain tissue from CAG140 and R6/2 mice. SERT mRNA and protein levels were analyzed using quantitative RT-PCR and immunoblotting. RESULTS AND CONCLUSIONS We found that SERT protein, but not mRNA is markedly increased in grade 4 HD patient striatal tissue. These findings suggest posttranscriptional or translational SERT dysregulation as a possible etiologic factor modulating psychopathology in HD. Interestingly, SERT expression is variable in mouse models of the disease. Increased SERT levels are demonstrated in the brain of CAG140 mice, a full-length knock-in mouse model of the disease, but not in the striatum of the R6/2 fragment murine model of the disease. Based on this parameter, the CAG140 huntingtin knock-in mouse model is more suitable than the R6/2 model for the study of serotonergic pathway pathology in Huntington's disease.
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Affiliation(s)
- Yanqing He
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA, USA
- Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Yalikun Suofu
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Svitlana Yablonska
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Xiaoming Wang
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Timothy M Larkin
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jinho Kim
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Diane L Carlisle
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA, USA
| | - Robert M Friedlander
- Neuroapoptosis Laboratory, Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA, USA
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16
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Jackson TC, Kotermanski SE, Kochanek PM. Whole-transcriptome microarray analysis reveals regulation of Rab4 by RBM5 in neurons. Neuroscience 2017; 361:93-107. [PMID: 28818525 PMCID: PMC5605467 DOI: 10.1016/j.neuroscience.2017.08.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 08/04/2017] [Accepted: 08/06/2017] [Indexed: 12/27/2022]
Abstract
RNA binding motif 5 (RBM5) is a nuclear protein that modulates gene transcription and mRNA splicing in cancer cells. The brain is among the highest RBM5-expressing organ in the body but its mRNA target(s) or functions in the CNS have not been elucidated. Here we knocked down (KO) RBM5 in primary rat cortical neurons and analyzed total RNA extracts by gene microarray vs. neurons transduced with lentivirus to deliver control (non-targeting) shRNA. The mRNA levels of Sec23A (involved in ER-Golgi transport) and the small GTPase Rab4a (involved in endocytosis/protein trafficking) were increased in RBM5 KO neurons relative to controls. At the protein level, only Rab4a was significantly increased in RBM5 KO extracts. Also, elevated Rab4a levels in KO neurons were associated with decreased membrane levels of oligomeric serotonin transporters (SERT). Finally, RBM5 KO was associated with increased uptake of membrane-derived monomeric SERT. SIGNIFICANCE Rab4a is involved in the regulation of endocytosis and protein trafficking in cells. In the CNS it regulates diverse neurobiological functions including (but not limited to) trafficking of transmembrane proteins involved in neurotransmission (e.g. SERT), maintaining dendritic spine size, promoting axonal growth, and modulating cognition. Our findings suggest that RBM5 regulates Rab4a in rat neurons.
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Affiliation(s)
- Travis C Jackson
- University of Pittsburgh School of Medicine, Safar Center for Resuscitation Research, Children's Hospital of Pittsburgh of UPMC, John G. Rangos Research Center - 6th Floor, 4401 Penn Avenue, Pittsburgh, PA 15224, United States; University of Pittsburgh School of Medicine, Department of Critical Care Medicine, Scaife Hall, 3550 Terrace Street, United States.
| | - Shawn E Kotermanski
- University of Pittsburgh School of Medicine, Department of Pharmacology and Chemical Biology, Bridgeside Point Building 1, 100 Technology Drive, United States
| | - Patrick M Kochanek
- University of Pittsburgh School of Medicine, Safar Center for Resuscitation Research, Children's Hospital of Pittsburgh of UPMC, John G. Rangos Research Center - 6th Floor, 4401 Penn Avenue, Pittsburgh, PA 15224, United States; University of Pittsburgh School of Medicine, Department of Critical Care Medicine, Scaife Hall, 3550 Terrace Street, United States
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17
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Super-resolution microscopy reveals functional organization of dopamine transporters into cholesterol and neuronal activity-dependent nanodomains. Nat Commun 2017; 8:740. [PMID: 28963530 PMCID: PMC5622129 DOI: 10.1038/s41467-017-00790-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 07/27/2017] [Indexed: 01/13/2023] Open
Abstract
Dopamine regulates reward, cognition, and locomotor functions. By mediating rapid reuptake of extracellular dopamine, the dopamine transporter is critical for spatiotemporal control of dopaminergic neurotransmission. Here, we use super-resolution imaging to show that the dopamine transporter is dynamically sequestrated into cholesterol-dependent nanodomains in the plasma membrane of presynaptic varicosities and neuronal projections of dopaminergic neurons. Stochastic optical reconstruction microscopy reveals irregular dopamine transporter nanodomains (∼70 nm mean diameter) that were highly sensitive to cholesterol depletion. Live photoactivated localization microscopy shows a similar dopamine transporter membrane organization in live heterologous cells. In neurons, dual-color dSTORM shows that tyrosine hydroxylase and vesicular monoamine transporter-2 are distinctively localized adjacent to, but not overlapping with, the dopamine transporter nanodomains. The molecular organization of the dopamine transporter in nanodomains is reversibly reduced by short-term activation of NMDA-type ionotropic glutamate receptors, implicating dopamine transporter nanodomain distribution as a potential mechanism to modulate dopaminergic neurotransmission in response to excitatory input.The dopamine transporter (DAT) has a crucial role in the regulation of neurotransmission. Here, the authors use super-resolution imaging to show that DAT clusters into cholesterol-dependent membrane regions that are reversibly regulated by ionotropic glutamate receptors activation.
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18
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Abstract
Maintaining synaptic integrity and function depends on the continuous removal and degradation of aged or damaged proteins. Synaptic protein degradation has received considerable attention in the context of synaptic plasticity and growing interest in relation to neurodegenerative and other disorders. Conversely, less attention has been given to constitutive, ongoing synaptic protein degradation and the roles canonical degradation pathways play in these processes. Here we briefly review recent progress on this topic and new experimental approaches which have expedited such progress and highlight several emerging principles. These include the realization that synaptic proteins typically have unusually long lifetimes, as might be expected from the remote locations of most synaptic sites; the possibility that degradation pathways can change with time from synthesis, cellular context, and physiological input; and that degradation pathways, other than ubiquitin-proteasomal-mediated degradation, might play key roles in constitutive protein degradation at synaptic sites. Finally, we point to the importance of careful experimental design and sufficiently sensitive techniques for studying synaptic protein degradation, which bring into account their slow turnover rates and complex life cycles.
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Affiliation(s)
- Laurie D Cohen
- Technion Faculty of Medicine, Rappaport Institute and Network Biology Research Laboratories, Technion City, Haifa, 32000, Israel
| | - Noam E Ziv
- Technion Faculty of Medicine, Rappaport Institute and Network Biology Research Laboratories, Technion City, Haifa, 32000, Israel
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19
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Bermingham DP, Blakely RD. Kinase-dependent Regulation of Monoamine Neurotransmitter Transporters. Pharmacol Rev 2016; 68:888-953. [PMID: 27591044 PMCID: PMC5050440 DOI: 10.1124/pr.115.012260] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Modulation of neurotransmission by the monoamines dopamine (DA), norepinephrine (NE), and serotonin (5-HT) is critical for normal nervous system function. Precise temporal and spatial control of this signaling in mediated in large part by the actions of monoamine transporters (DAT, NET, and SERT, respectively). These transporters act to recapture their respective neurotransmitters after release, and disruption of clearance and reuptake has significant effects on physiology and behavior and has been linked to a number of neuropsychiatric disorders. To ensure adequate and dynamic control of these transporters, multiple modes of control have evolved to regulate their activity and trafficking. Central to many of these modes of control are the actions of protein kinases, whose actions can be direct or indirectly mediated by kinase-modulated protein interactions. Here, we summarize the current state of our understanding of how protein kinases regulate monoamine transporters through changes in activity, trafficking, phosphorylation state, and interacting partners. We highlight genetic, biochemical, and pharmacological evidence for kinase-linked control of DAT, NET, and SERT and, where applicable, provide evidence for endogenous activators of these pathways. We hope our discussion can lead to a more nuanced and integrated understanding of how neurotransmitter transporters are controlled and may contribute to disorders that feature perturbed monoamine signaling, with an ultimate goal of developing better therapeutic strategies.
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Affiliation(s)
- Daniel P Bermingham
- Department of Pharmacology (D.P.B., R.D.B.) and Psychiatry (R.D.B.), Vanderbilt University Medical Center, Nashville, Tennessee; and Department of Biomedical Sciences, Charles E. Schmidt College of Medicine and Brain Institute, Florida Atlantic University, Jupiter, Florida (R.D.B.)
| | - Randy D Blakely
- Department of Pharmacology (D.P.B., R.D.B.) and Psychiatry (R.D.B.), Vanderbilt University Medical Center, Nashville, Tennessee; and Department of Biomedical Sciences, Charles E. Schmidt College of Medicine and Brain Institute, Florida Atlantic University, Jupiter, Florida (R.D.B.)
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20
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A kinome wide screen identifies novel kinases involved in regulation of monoamine transporter function. Neurochem Int 2016; 98:103-14. [DOI: 10.1016/j.neuint.2016.03.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/08/2016] [Accepted: 03/16/2016] [Indexed: 11/21/2022]
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21
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Blagojević Zagorac G, Mahmutefendić H, Maćešić S, Karleuša L, Lučin P. Quantitative Analysis of Endocytic Recycling of Membrane Proteins by Monoclonal Antibody-Based Recycling Assays. J Cell Physiol 2016; 232:463-476. [DOI: 10.1002/jcp.25503] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 07/25/2016] [Indexed: 12/27/2022]
Affiliation(s)
| | - Hana Mahmutefendić
- Department of Physiology and Immunology; University of Rijeka Faculty of Medicine; Rijeka Croatia
| | - Senka Maćešić
- Department of Mathematics, Physics, Foreign Languages and Kinesiology; University of Rijeka Faculty of Engineering; Rijeka Croatia
| | - Ljerka Karleuša
- Department of Physiology and Immunology; University of Rijeka Faculty of Medicine; Rijeka Croatia
| | - Pero Lučin
- Department of Physiology and Immunology; University of Rijeka Faculty of Medicine; Rijeka Croatia
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22
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Increased expression of endocytosis-Related proteins in rat hippocampus following 10-day electroconvulsive seizure treatment. Neurosci Lett 2016; 624:85-91. [PMID: 27177725 DOI: 10.1016/j.neulet.2016.05.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 05/06/2016] [Accepted: 05/09/2016] [Indexed: 12/16/2022]
Abstract
Although electroconvulsive therapy (ECT) is clinically used for severe depression and drug-resistant Parkinson's disease, its exact biological background and mechanism have not yet been fully elucidated. Two potential explanations have been presented so far to explain the increased neuroplastic and resilient profiles of multiple ECT administrations. One is the alteration of central neurotransmitter receptor densities and the other is the expressional upregulation of brain derived neurotrophic factor in various brain regions with enhanced hippocampal neurogenesis and mossy fiber sprouting. In the present report, western blot analyses revealed significantly upregulated expression of various endocytosis-related proteins following 10-day electroconvulsive seizure (ECS) treatment in rat hippocampal homogenates and hippocampal lipid raft fractions extracted using an ultracentrifugation procedure. Upregulated proteins included endocytosis-related scaffolding proteins (caveolin-1, flotillin-1, and heavy and light chains of clathrin) and small GTPases (Rab5, Rab7, Rab11, and Rab4) specifically expressed on various types of endosomes. Two scaffolding proteins, caveolin-1 and flotillin-1, were also increased in the lipid raft fraction. Together with our previous finding of increased autophagy-related proteins in the hippocampal region, the present results suggest membrane trafficking machinery is enhanced following 10-day ECS treatment. We consider that the membrane trafficking machinery that transports functional proteins in the neuronal cells and from or into the synaptic membranes is one of the new candidates supporting the cellular and behavioral neuroplastic profiles of ECS treatments in animal experiments and ECT administrations in clinical settings.
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Vuorenpää A, Jørgensen TN, Newman AH, Madsen KL, Scheinin M, Gether U. Differential Internalization Rates and Postendocytic Sorting of the Norepinephrine and Dopamine Transporters Are Controlled by Structural Elements in the N Termini. J Biol Chem 2016; 291:5634-5651. [PMID: 26786096 DOI: 10.1074/jbc.m115.702050] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Indexed: 11/06/2022] Open
Abstract
The norepinephrine transporter (NET) mediates reuptake of synaptically released norepinephrine in central and peripheral noradrenergic neurons. The molecular processes governing availability of NET in the plasma membrane are poorly understood. Here we use the fluorescent cocaine analogue JHC 1-64, as well as several other approaches, to investigate the trafficking itinerary of NET in live noradrenergic neurons. Confocal imaging revealed extensive constitutive internalization of JHC 1-64-labeled NET in the neuronal somata, proximal extensions and presynaptic boutons. Phorbol 12-myristate 13-acetate increased intracellular accumulation of JHC 1-64-labeled NET and caused a parallel reduction in uptake capacity. Internalized NET strongly colocalized with the "long loop" recycling marker Rab11, whereas less overlap was seen with the "short loop" recycling marker Rab4 and the late endosomal marker Rab7. Moreover, mitigating Rab11 function by overexpression of dominant negative Rab11 impaired NET function. Sorting of NET to the Rab11 recycling compartment was further supported by confocal imaging and reversible biotinylation experiments in transfected differentiated CATH.a cells. In contrast to NET, the dopamine transporter displayed markedly less constitutive internalization and limited sorting to the Rab11 recycling compartment in the differentiated CATH.a cells. Exchange of domains between the two homologous transporters revealed that this difference was determined by non-conserved structural elements in the intracellular N terminus. We conclude that NET displays a distinct trafficking itinerary characterized by continuous shuffling between the plasma membrane and the Rab11 recycling compartment and that the functional integrity of the Rab11 compartment is critical for maintaining proper presynaptic NET function.
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Affiliation(s)
- Anne Vuorenpää
- From the Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, Panum Institute 18.6, University of Copenhagen, DK-2200 Copenhagen, Denmark,; the Department of Pharmacology, Drug Development, and Therapeutics, University of Turku, Turku FI-20014, Finland,; the Unit of Clinical Pharmacology, Turku University Hospital, Turku FI-20520, Finland, and
| | - Trine N Jørgensen
- From the Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, Panum Institute 18.6, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Amy H Newman
- the Medicinal Chemistry Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224
| | - Kenneth L Madsen
- From the Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, Panum Institute 18.6, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Mika Scheinin
- the Department of Pharmacology, Drug Development, and Therapeutics, University of Turku, Turku FI-20014, Finland,; the Unit of Clinical Pharmacology, Turku University Hospital, Turku FI-20520, Finland, and
| | - Ulrik Gether
- From the Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, Panum Institute 18.6, University of Copenhagen, DK-2200 Copenhagen, Denmark,.
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24
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Akt-mediated regulation of antidepressant-sensitive serotonin transporter function, cell-surface expression and phosphorylation. Biochem J 2015; 468:177-90. [PMID: 25761794 DOI: 10.1042/bj20140826] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The present study is focused on the cellular basis for Akt-mediated SERT regulation. SERT has been implicated in mood disorders. SERT is a primary target for antidepressants used in the therapeutic intervention of psychiatric disorders.
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25
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El-Kasaby A, Koban F, Sitte HH, Freissmuth M, Sucic S. A cytosolic relay of heat shock proteins HSP70-1A and HSP90β monitors the folding trajectory of the serotonin transporter. J Biol Chem 2014; 289:28987-9000. [PMID: 25202009 PMCID: PMC4200255 DOI: 10.1074/jbc.m114.595090] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Mutations in the C terminus of the serotonin transporter (SERT) disrupt folding and export from the endoplasmic reticulum. Here we examined the hypothesis that a cytosolic heat shock protein relay was recruited to the C terminus to assist folding of SERT. This conjecture was verified by the following observations. (i) The proximal portion of the SERT C terminus conforms to a canonical binding site for DnaK/heat shock protein of 70 kDa (HSP70). A peptide covering this segment stimulated ATPase activity of purified HSP70-1A. (ii) A GST fusion protein comprising the C terminus of SERT pulled down HSP70-1A. The interaction between HSP70-1A and SERT was visualized in live cells by Förster resonance energy transfer: it was restricted to endoplasmic reticulum-resident transporters and enhanced by an inhibitor that traps HSP70-1A in its closed state. (iv) Co-immunoprecipitation confirmed complex formation of SERT with HSP70-1A and HSP90β. Consistent with an HSP relay, co-chaperones (e.g. HSC70-HSP90-organizing protein) were co-immunoprecipitated with the stalled mutants SERT-R607A/I608A and SERT-P601A/G602A. (v) Depletion of HSP90β by siRNA or its inhibition increased the cell surface expression of wild type SERT and SERT-F604Q. In contrast, SERT-R607A/I608A and SERT-P601A/G602A were only rendered susceptible to inhibition of HSP70 and HSP90 by concomitant pharmacochaperoning with noribogaine. (vi) In JAR cells, inhibition of HSP90 also increased the levels of SERT, indicating that endogenously expressed transporter was also susceptible to control by HSP90β. These findings support the concept that the folding trajectory of SERT is sampled by a cytoplasmic chaperone relay.
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Affiliation(s)
- Ali El-Kasaby
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and the Department of Pharmacology, Faculty of Veterinary Medicine, Mansoura University, 35516 Mansoura, Egypt
| | - Florian Koban
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
| | - Harald H Sitte
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
| | - Michael Freissmuth
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
| | - Sonja Sucic
- From the Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria and
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