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Meyer UA, Amara SG, Blaschke TF, Insel PA. Introduction to the Theme "Pharmacological Individuality: New Insights and Strategies for Personalized and Precise Drug Treatment". Annu Rev Pharmacol Toxicol 2024; 64:27-31. [PMID: 37816308 DOI: 10.1146/annurev-pharmtox-090123-010552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
The reviews in Volume 64 of the Annual Review of Pharmacology and Toxicology cover diverse topics. A common theme in many of the reviews is the interindividual variability in the clinical response to drugs. Highlighted areas include emerging developments in pharmacogenomics that can predict the personal risk for drug inefficacy and/or adverse drug reactions. Other reviews focus on the use of circulating biomarkers to define drug metabolism phenotypes and the effect of circadian regulation on drug response. Another emerging technology, digital twins that model individual patients, is used to generate computational simulations of drug effects and identify optimal personalized treatments. Another variable that may affect clinical outcomes, the nocebo response (an adverse reaction to a placebo), complicates clinical trials. These reviews further document that pharmacological individuality is an essential component of the concepts of personalized medicine and precision medicine and will likely have an important impact on patient care.
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Affiliation(s)
- Urs A Meyer
- Biozentrum, University of Basel, Basel, Switzerland;
| | - Susan G Amara
- National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA
| | | | - Paul A Insel
- Departments of Pharmacology and Medicine, University of California, San Diego, La Jolla, California, USA
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Meyer UA, Amara SG, Blaschke TF, Insel PA. Introduction to the Theme "Pharmacological Individuality: New Insights and Strategies for Personalized and Precise Drug Treatment". Annu Rev Pharmacol Toxicol 2023; 64. [PMID: 37816308 DOI: 10.1146/annurev-physiol-090123-010552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
The reviews in Volume 64 of the Annual Review of Pharmacology and Toxicology cover diverse topics. A common theme in many of the reviews is the interindividual variability in the clinical response to drugs. Highlighted areas include emerging developments in pharmacogenomics that can predict the personal risk for drug inefficacy and/or adverse drug reactions. Other reviews focus on the use of circulating biomarkers to define drug metabolism phenotypes and the effect of circadian regulation on drug response. Another emerging technology, digital twins that model individual patients, is used to generate computational simulations of drug effects and identify optimal personalized treatments. Another variable that may affect clinical outcomes, the nocebo response (an adverse reaction to a placebo), complicates clinical trials. These reviews further document that pharmacological individuality is an essential component of the concepts of personalized medicine and precision medicine and will likely have an important impact on patient care. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 64 is January 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Urs A Meyer
- Biozentrum, University of Basel, Basel, Switzerland;
| | - Susan G Amara
- National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA
| | | | - Paul A Insel
- Departments of Pharmacology and Medicine, University of California, San Diego, La Jolla, California, USA
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Blaschke TF, Insel PA, Amara SG, Meyer UA. Introduction to the Theme "Development of New Drugs: Moving from the Bench to Bedside and Improved Patient Care". Annu Rev Pharmacol Toxicol 2023; 63:15-18. [PMID: 36270297 DOI: 10.1146/annurev-pharmtox-091222-022612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Investigations in pharmacology and toxicology range from molecular studies to clinical care. Studies in basic and clinical pharmacology and in preclinical and clinical toxicology are all essential in bringing new knowledge and new drugs into clinical use. The 30 reviews in Volume 63 of the Annual Review of Pharmacology and Toxicology explore topics across this spectrum. Examples include "Zebrafish as a Mainstream Model for In Vivo Systems Pharmacology and Toxicology" and "Artificial Intelligence and Machine Learning for Lead-to-Candidate Decision-Making and Beyond." Other reviews discuss components important for drug discovery and development and the use of pharmaceuticals in a variety of diseases. Air pollution continues to increase globally; accordingly, "Air Pollution-Related Neurotoxicity Across the Life Span" is a timely and forward-thinking review. Volume 63 also explores the use of contemporary technologies such as electronic health records, pharmacogenetics, and new drug delivery systems that help enhance and improve the utility of new therapies.
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Affiliation(s)
| | - Paul A Insel
- Departments of Pharmacology and Medicine, University of California, San Diego, La Jolla, California, USA
| | - Susan G Amara
- National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA
| | - Urs A Meyer
- Biozentrum, University of Basel, Basel, Switzerland
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Radhakrishnan S, Amara SG. Cellular redox regulation by the neuronal glutamate and cysteine transporter, EAAT3. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.l7661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Saranya Radhakrishnan
- Laboratory for Molecular and Cellular NeurobiologyNational Institute of Mental HealthBethesdaMD
| | - Susan G. Amara
- Laboratory for Molecular and Cellular NeurobiologyNational Institute of Mental HealthBethesdaMD
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Abstract
This week (17 to 20 February), the virtual annual meeting of the American Association for the Advancement of Science (AAAS, the publisher of Science) will address the challenges of building the public's trust and understanding of science by illuminating both great science and innovative initiatives in advocacy, education, and policy. The theme, "Empower with Evidence," speaks to the critical importance of decision-making, policy-making, and interventions that are grounded in knowledge and facts, not opinions-or worse, misinformation.
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Affiliation(s)
- Susan G Amara
- Susan G. Amara is president of the American Association for the Advancement of Science, Washington, DC, USA
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Insel PA, Blaschke TF, Amara SG, Meyer UA. Introduction to the Theme "New Insights, Strategies, and Therapeutics for Common Diseases". Annu Rev Pharmacol Toxicol 2021; 62:19-24. [PMID: 34606327 DOI: 10.1146/annurev-pharmtox-091421-094627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The reviews in Volume 62 of the Annual Review of Pharmacology and Toxicology (ARPT) cover a diverse range of topics. A theme that encompasses many of these reviews is their relevance to common diseases and disorders, including type 2 diabetes, heart failure, cancer, tuberculosis, Alzheimer's disease, neurodegenerative disorders, and Down syndrome. Other reviews highlight important aspects of therapeutics, including placebos and patient-centric approaches to drug formulation. The reviews with this thematic focus, as well as other reviews in this volume, emphasize new mechanistic insights, experimental and therapeutic strategies, and novel insights regarding topics in the disciplines of pharmacology and toxicology. As the editors of ARPT, we believe that these reviews help advance those disciplines and, even more importantly, have the potential to improve the health care of the world's population. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Paul A Insel
- Departments of Pharmacology and Medicine, University of California, San Diego, La Jolla, California 92093, USA;
| | | | - Susan G Amara
- National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Urs A Meyer
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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Abstract
The theme of Volume 61 is "Old and New Toxicology: Interfaces with Pharmacology." Old toxicology is exemplified by the authors of the autobiographical articles: B.M. Olivera's work on toxins and venoms from cone snails and P. Taylor's studies of acetylcholinesterase and the nicotinic cholinergic receptor, which serve as sites of action for numerous pesticides and venoms. Other articles in this volume focus on new understanding and new types of toxicology, including (a) arsenic toxicity, which is an ancient poison that, through evolution, has caused most multicellular organisms to express an active arsenic methyltransferase to methylate arsenite, which accelerates the excretion of arsenic from the body; (b) small molecules that react with lipid dicarbonyls, which are now considered the most toxic oxidative stress end products; (c) immune checkpoint inhibitors (ICIs), which have revolutionized cancer therapy but have numerous immune-related adverse events, including cardiovascular complications; (d) autoimmunity caused by the environment; (e) idiosyncratic drug-induced liver disease, which together with the toxicity of ICIs represents new toxicology interfacing with pharmacology; and (f) sex differences in the development of cardiovascular disease, with men more susceptible than women to vascular inflammation that initiates and perpetuates disease. These articles and others in Volume 61 reflect the interface and close integration of pharmacology and toxicology that began long ago but continues today.
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Affiliation(s)
- Max Costa
- Department of Environmental Medicine, NYU Grossman School of Medicine, New York, New York 10010, USA;
| | | | - Susan G Amara
- National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Urs A Meyer
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | - Paul A Insel
- Departments of Pharmacology and Medicine, University of California, San Diego, La Jolla, California 92093, USA
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Underhill SM, Amara SG. Acetylcholine Receptor Stimulation Activates Protein Kinase C Mediated Internalization of the Dopamine Transporter. Front Cell Neurosci 2021; 15:662216. [PMID: 33897375 PMCID: PMC8062973 DOI: 10.3389/fncel.2021.662216] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 03/11/2021] [Indexed: 11/13/2022] Open
Abstract
The dopamine transporter (DAT) clears neurotransmitters from the extracellular space and serves as an important regulator of signal amplitude and duration at sites of dopamine release. Several different intracellular signaling pathways have been observed to modulate DAT activity through the regulation of the trafficking of the carriers to and from the cell surface. Acute activation of protein kinase C (PKC) by phorbol esters facilitates clathrin-dependent internalization of the DAT in a variety of model systems; however, the physiological stimuli and cell-surface receptor systems that activate PKC and regulate the DAT in dopamine neurons remain elusive. We report here that stimulation of M1/M5 muscarinic receptors in midbrain cultures decreases the ability of dopamine neurons to transport dopamine through DAT. Application of the cholinomimetic drug carbachol leads to a decrease in DAT activity in primary cultures while the M1/M5-specific antagonist, pirenzepine, blocks these effects. The M3 antagonist, DAU 5884, does not affect, but a positive modulator of M5, VU 0238429, enhances the loss of DAT function in response to carbachol and acetylcholine. These data implicate M1/M5 receptors on dopamine neurons in the modulation of DAT function. Bisindolylmaleimide, a PKC inhibitor, blocks the effects of carbachol stimulation on dopamine uptake, supporting a role for PKC in muscarinic receptor-mediated DAT internalization. Furthermore, as shown previously for PKC-induced internalization, downregulation of the DAT is dependent on both clathrin and dynamin. A Gq-specific inhibitor peptide also blocks the effects of carbachol on DAT in primary cultures, confirming Gq as the G-protein that couples M1/M5 receptors to PKC activation in these cells. In acute midbrain slices, biotinylation of cell-surface proteins revealed the loss of dopamine transport mediated by muscarinic receptor stimulation was, indeed, due to loss of membrane expression of the DAT in endogenous tissue. These data indicate that stimulation of cholinergic pathways can lead to modulation of dopamine through internalization of the DAT.
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Affiliation(s)
- Suzanne M Underhill
- National Institute of Mental Health, National Institutes of Health (NIH), Bethesda, MD, United States
| | - Susan G Amara
- National Institute of Mental Health, National Institutes of Health (NIH), Bethesda, MD, United States
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Unger EK, Keller JP, Altermatt M, Liang R, Matsui A, Dong C, Hon OJ, Yao Z, Sun J, Banala S, Flanigan ME, Jaffe DA, Hartanto S, Carlen J, Mizuno GO, Borden PM, Shivange AV, Cameron LP, Sinning S, Underhill SM, Olson DE, Amara SG, Temple Lang D, Rudnick G, Marvin JS, Lavis LD, Lester HA, Alvarez VA, Fisher AJ, Prescher JA, Kash TL, Yarov-Yarovoy V, Gradinaru V, Looger LL, Tian L. Directed Evolution of a Selective and Sensitive Serotonin Sensor via Machine Learning. Cell 2020; 183:1986-2002.e26. [PMID: 33333022 PMCID: PMC8025677 DOI: 10.1016/j.cell.2020.11.040] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 06/22/2020] [Accepted: 11/20/2020] [Indexed: 12/28/2022]
Abstract
Serotonin plays a central role in cognition and is the target of most pharmaceuticals for psychiatric disorders. Existing drugs have limited efficacy; creation of improved versions will require better understanding of serotonergic circuitry, which has been hampered by our inability to monitor serotonin release and transport with high spatial and temporal resolution. We developed and applied a binding-pocket redesign strategy, guided by machine learning, to create a high-performance, soluble, fluorescent serotonin sensor (iSeroSnFR), enabling optical detection of millisecond-scale serotonin transients. We demonstrate that iSeroSnFR can be used to detect serotonin release in freely behaving mice during fear conditioning, social interaction, and sleep/wake transitions. We also developed a robust assay of serotonin transporter function and modulation by drugs. We expect that both machine-learning-guided binding-pocket redesign and iSeroSnFR will have broad utility for the development of other sensors and in vitro and in vivo serotonin detection, respectively.
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Affiliation(s)
- Elizabeth K Unger
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Jacob P Keller
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20174, USA
| | - Michael Altermatt
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Ruqiang Liang
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Aya Matsui
- Laboratory on Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - Chunyang Dong
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Olivia J Hon
- Bowles Center for Alcohol Studies, Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Zi Yao
- Department of Chemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - Junqing Sun
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Samba Banala
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20174, USA
| | - Meghan E Flanigan
- Bowles Center for Alcohol Studies, Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - David A Jaffe
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Samantha Hartanto
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Jane Carlen
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Grace O Mizuno
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Phillip M Borden
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20174, USA
| | - Amol V Shivange
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Lindsay P Cameron
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Steffen Sinning
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Suzanne M Underhill
- Laboratory of Molecular and Cellular Neurobiology, National Institute on Mental Health, NIH, Bethesda, MD 20892, USA
| | - David E Olson
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Susan G Amara
- Laboratory of Molecular and Cellular Neurobiology, National Institute on Mental Health, NIH, Bethesda, MD 20892, USA
| | - Duncan Temple Lang
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Gary Rudnick
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20174, USA
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20174, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Veronica A Alvarez
- Laboratory on Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - Andrew J Fisher
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Jennifer A Prescher
- Department of Chemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - Thomas L Kash
- Bowles Center for Alcohol Studies, Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Vladimir Yarov-Yarovoy
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA
| | - Viviana Gradinaru
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20174, USA.
| | - Lin Tian
- Departments of Biochemistry and Molecular Medicine, Chemistry, Statistics, Molecular and Cellular Biology, and Physiology and Membrane Biology, the Center for Neuroscience, and Graduate Programs in Molecular, Cellular, and Integrative Physiology, Biochemistry, Molecular, Cellular and Developmental Biology and Neuroscience, University of California, Davis, Davis, CA 95616, USA.
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Bäck S, Necarsulmer J, Whitaker LR, Coke LM, Koivula P, Heathward EJ, Fortuno LV, Zhang Y, Yeh CG, Baldwin HA, Spencer MD, Mejias-Aponte CA, Pickel J, Hoffman AF, Spivak CE, Lupica CR, Underhill SM, Amara SG, Domanskyi A, Anttila JE, Airavaara M, Hope BT, Hamra FK, Richie CT, Harvey BK. Neuron-Specific Genome Modification in the Adult Rat Brain Using CRISPR-Cas9 Transgenic Rats. Neuron 2019; 102:105-119.e8. [PMID: 30792150 DOI: 10.1016/j.neuron.2019.01.035] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 12/13/2018] [Accepted: 01/16/2019] [Indexed: 12/28/2022]
Abstract
Historically, the rat has been the preferred animal model for behavioral studies. Limitations in genome modification have, however, caused a lag in their use compared to the bevy of available transgenic mice. Here, we have developed several transgenic tools, including viral vectors and transgenic rats, for targeted genome modification in specific adult rat neurons using CRISPR-Cas9 technology. Starting from wild-type rats, knockout of tyrosine hydroxylase was achieved with adeno-associated viral (AAV) vectors expressing Cas9 or guide RNAs (gRNAs). We subsequently created an AAV vector for Cre-dependent gRNA expression as well as three new transgenic rat lines to specifically target CRISPR-Cas9 components to dopaminergic neurons. One rat represents the first knockin rat model made by germline gene targeting in spermatogonial stem cells. The rats described herein serve as a versatile platform for making cell-specific and sequence-specific genome modifications in the adult brain and potentially other Cre-expressing tissues of the rat.
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Affiliation(s)
- Susanne Bäck
- Molecular Mechanisms of Cellular Stress and Inflammation Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Julie Necarsulmer
- Optogenetics and Transgenic Technology Core/Genetic Engineering and Viral Vector Core, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Leslie R Whitaker
- Neuronal Ensembles in Drug Addiction Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Lamarque M Coke
- Molecular Mechanisms of Cellular Stress and Inflammation Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Pyry Koivula
- Molecular Mechanisms of Cellular Stress and Inflammation Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Emily J Heathward
- Optogenetics and Transgenic Technology Core/Genetic Engineering and Viral Vector Core, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Lowella V Fortuno
- Optogenetics and Transgenic Technology Core/Genetic Engineering and Viral Vector Core, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Yajun Zhang
- Optogenetics and Transgenic Technology Core/Genetic Engineering and Viral Vector Core, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - C Grace Yeh
- Neuronal Ensembles in Drug Addiction Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Heather A Baldwin
- Molecular Mechanisms of Cellular Stress and Inflammation Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Morgan D Spencer
- Molecular Mechanisms of Cellular Stress and Inflammation Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Carlos A Mejias-Aponte
- Histology Core, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - James Pickel
- Transgenic Technology Core, Intramural Research Program, National Institute of Mental Health, Bethesda, MD 20892, USA
| | - Alexander F Hoffman
- Electrophysiology Research Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Charles E Spivak
- Electrophysiology Research Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Carl R Lupica
- Electrophysiology Research Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Suzanne M Underhill
- Laboratory of Molecular and Cellular Neurobiology, Intramural Research Program, National Institute of Mental Health, Bethesda, MD 20892, USA
| | - Susan G Amara
- Laboratory of Molecular and Cellular Neurobiology, Intramural Research Program, National Institute of Mental Health, Bethesda, MD 20892, USA
| | - Andrii Domanskyi
- Institute of Biotechnology, HiLIFE, University of Helsinki, 00014 Helsinki, Finland
| | - Jenni E Anttila
- Institute of Biotechnology, HiLIFE, University of Helsinki, 00014 Helsinki, Finland
| | - Mikko Airavaara
- Institute of Biotechnology, HiLIFE, University of Helsinki, 00014 Helsinki, Finland
| | - Bruce T Hope
- Neuronal Ensembles in Drug Addiction Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - F Kent Hamra
- Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Christopher T Richie
- Optogenetics and Transgenic Technology Core/Genetic Engineering and Viral Vector Core, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Brandon K Harvey
- Molecular Mechanisms of Cellular Stress and Inflammation Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA; Optogenetics and Transgenic Technology Core/Genetic Engineering and Viral Vector Core, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA.
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11
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Insel PA, Amara SG, Blaschke TF, Meyer UA. Introduction to the Theme “New Therapeutic Targets”. Annu Rev Pharmacol Toxicol 2019; 59:15-20. [DOI: 10.1146/annurev-pharmtox-101018-112717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
“New Therapeutic Targets” is the theme of articles in the Annual Review of Pharmacology and Toxicology, Volume 59. Reviews in this volume discuss targets for a variety of conditions in need of new therapies, including type 2 diabetes, heart failure with preserved ejection fraction, obesity, thyroid-associated ophthalmopathy, tinnitus, multiple sclerosis, Parkinson's disease and other neurodegenerative diseases, pain, depression, post-traumatic stress disorder, muscle wasting diseases, cancer, and anemia associated with chronic renal disease. Numerous articles in this volume focus on the identification, validation, and utility of novel therapeutic targets, in particular, ones that involve new or unexpected molecular entities. This theme complements several previous themes, including “New Approaches for Studying Drug and Toxicant Action: Applications to Drug Discovery and Development,” “Precision Medicine and Prediction in Pharmacology,” and “New Methods and Novel Therapeutic Approaches in Pharmacology and Toxicology.”
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Affiliation(s)
- Paul A. Insel
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093, USA
- Department of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | - Susan G. Amara
- National Institute of Mental Health, Bethesda, Maryland 20892, USA
| | - Terrence F. Blaschke
- Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Urs A. Meyer
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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12
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Underhill SM, Ingram SL, Ahmari SE, Veenstra-VanderWeele J, Amara SG. Neuronal excitatory amino acid transporter EAAT3: Emerging functions in health and disease. Neurochem Int 2018; 123:69-76. [PMID: 29800605 DOI: 10.1016/j.neuint.2018.05.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 05/18/2018] [Accepted: 05/21/2018] [Indexed: 01/09/2023]
Affiliation(s)
- Suzanne M Underhill
- National Institutes of Health, National Institute of Mental Health, 35 Convent Drive, Bethesda, MD 20892, USA.
| | - Susan L Ingram
- Department of Neurological Surgery, Oregon Health & Science University (OHSU), 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Susanne E Ahmari
- Department of Psychiatry, University of Pittsburgh, 450 Technology Drive, Room 227, Pittsburgh, PA 15219, USA
| | - Jeremy Veenstra-VanderWeele
- Department of Psychiatry, Columbia University, New York State Psychiatric Institute, 1051 Riverside Drive, Mail Unit 78, New York, NY, 10032, USA
| | - Susan G Amara
- National Institutes of Health, National Institute of Mental Health, 35 Convent Drive, Bethesda, MD 20892, USA
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13
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Garcia‐Olivares J, Torres‐Salazar D, Wasserman SA, Hong CW, Amara SG. Interaction between the dopamine transporter and the Gβγ subunits of the heterotrimeric G‐protein modifies transporter function and response to psychostimulants. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.680.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | - Conrad W. Hong
- Department of Pharmaceutical SciencesButtler UniversityIndianapolisIN
| | - Susan G. Amara
- Laboratory of Cellular and Molecular NeurobiologyNIMHBethesdaMD
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14
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Skirzewski M, Karavanova I, Shamir A, Erben L, Garcia-Olivares J, Shin JH, Vullhorst D, Alvarez VA, Amara SG, Buonanno A. ErbB4 signaling in dopaminergic axonal projections increases extracellular dopamine levels and regulates spatial/working memory behaviors. Mol Psychiatry 2018; 23:2227-2237. [PMID: 28727685 PMCID: PMC5775946 DOI: 10.1038/mp.2017.132] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 03/13/2017] [Accepted: 04/04/2017] [Indexed: 02/07/2023]
Abstract
Genetic variants of Neuregulin 1 (NRG1) and its neuronal tyrosine kinase receptor ErbB4 are associated with risk for schizophrenia, a neurodevelopmental disorder characterized by excitatory/inhibitory imbalance and dopamine (DA) dysfunction. To date, most ErbB4 studies have focused on GABAergic interneurons in the hippocampus and neocortex, particularly fast-spiking parvalbumin-positive (PV+) basket cells. However, NRG has also been shown to modulate DA levels, suggesting a role for ErbB4 signaling in dopaminergic neuron function. Here we report that ErbB4 in midbrain DAergic axonal projections regulates extracellular DA levels and relevant behaviors. Mice lacking ErbB4 in tyrosine hydroxylase-positive (TH+) neurons, but not in PV+ GABAergic interneurons, exhibit different regional imbalances of basal DA levels and fail to increase DA in response to local NRG1 infusion into the dorsal hippocampus, medial prefrontal cortex and dorsal striatum measured by reverse microdialysis. Using Lund Human Mesencephalic (LUHMES) cells, we show that NRG/ErbB signaling increases extracellular DA levels, at least in part, by reducing DA transporter (DAT)-dependent uptake. Interestingly, TH-Cre;ErbB4f/f mice manifest deficits in learning, spatial and working memory-related behaviors, but not in numerous other behaviors altered in PV-Cre;ErbB4f/f mice. Importantly, microinjection of a Cre-inducible ErbB4 virus (AAV-ErbB4.DIO) into the mesencephalon of TH-Cre;ErbB4f/f mice, which selectively restores ErbB4 expression in DAergic neurons, rescues DA dysfunction and ameliorates behavioral deficits. Our results indicate that direct NRG/ErbB4 signaling in DAergic axonal projections modulates DA homeostasis, and that NRG/ErbB4 signaling in both GABAergic interneurons and DA neurons contribute to the modulation of behaviors relevant to psychiatric disorders.
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Affiliation(s)
- M Skirzewski
- 0000 0001 2297 5165grid.94365.3dSection on Molecular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD USA
| | - I Karavanova
- 0000 0001 2297 5165grid.94365.3dSection on Molecular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD USA
| | - A Shamir
- 0000 0001 2297 5165grid.94365.3dSection on Molecular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD USA
| | - L Erben
- 0000 0001 2297 5165grid.94365.3dSection on Molecular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD USA ,0000 0001 2240 3300grid.10388.32Institute of Molecular Psychiatry, University of Bonn, Bonn, Germany
| | - J Garcia-Olivares
- 0000 0001 2297 5165grid.94365.3dLaboratory of Molecular and Cellular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD USA
| | - J H Shin
- 0000 0001 2297 5165grid.94365.3dLaboratory for Integrative Neuroscience, Section on Neuronal Structure, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD USA
| | - D Vullhorst
- 0000 0001 2297 5165grid.94365.3dSection on Molecular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD USA
| | - V A Alvarez
- 0000 0001 2297 5165grid.94365.3dLaboratory for Integrative Neuroscience, Section on Neuronal Structure, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD USA
| | - S G Amara
- 0000 0001 2297 5165grid.94365.3dLaboratory of Molecular and Cellular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD USA
| | - A Buonanno
- Section on Molecular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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15
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Insel PA, Amara SG, Blaschke TF, Meyer UA. Introduction to the Theme "New Approaches for Studying Drug and Toxicant Action: Applications to Drug Discovery and Development". Annu Rev Pharmacol Toxicol 2017; 58:33-36. [PMID: 29058990 DOI: 10.1146/annurev-pharmtox-092617-121952] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The theme "New Approaches for Studying Drug and Toxicant Action: Applications to Drug Discovery and Development" links 13 articles in this volume of the Annual Review of Pharmacology and Toxicology (ARPT). The engaging prefatory articles by Arthur Cho and Robert Lefkowitz set the stage for this theme and for the reviews that insightfully describe new approaches that advance research and discovery in pharmacology and toxicology. Examples include the progress being made in developing Organs-on-Chips/microphysiological systems and human induced pluripotent stem cell-derived cells to aid in understanding cell and tissue pharmacokinetics, action, and toxicity; the recognition of the importance of circadian rhythm, the microbiome, and epigenetics in drug and toxicant responses; and the application of results from new types of patient-derived information to create personalized/precision medicine, including therapeutics for pain, which may perhaps provide help in dealing with the opioid epidemic in the United States. Such new information energizes discovery efforts in pharmacology and toxicology that seek to improve the efficacy and safety of drugs in patients and to minimize the consequences of exposure to toxins.
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Affiliation(s)
- Paul A Insel
- Department of Pharmacology and Department of Medicine, University of California, San Diego, La Jolla, California 92093, USA
| | - Susan G Amara
- National Institute of Mental Health, Bethesda, Maryland 20892, USA
| | - Terrence F Blaschke
- Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Urs A Meyer
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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16
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Mortensen OV, Larsen MB, Amara SG. MAP Kinase Phosphatase 3 (MKP3) Preserves Norepinephrine Transporter Activity by Modulating ERK1/2 Kinase-Mediated Gene Expression. Front Cell Neurosci 2017; 11:253. [PMID: 28878626 PMCID: PMC5572231 DOI: 10.3389/fncel.2017.00253] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 08/08/2017] [Indexed: 12/03/2022] Open
Abstract
The norepinephrine transporter (NET) mediates the clearance of norepinephrine (NE) from the extracellular space and is a target of therapeutic antidepressants and psychostimulants. Previously we identified a MAP kinase phosphatase 3 (MKP3), as an important modulator of protein kinase C (PKC) mediated internalization of the related dopamine transporter (DAT). Here we show that MKP3 decreases PKC-mediated down regulation of NET expressed in PC12 cells. We demonstrate that this process involves a PKC-stimulated decrease of NET surface expression that is dependent on dynamin. Surprisingly, MAP kinase inhibitors have no effect on the PKC-mediated regulation of NET activity, suggesting that, like PKC-mediated regulation of the DAT, the acute activation of MAP kinases is not likely to be involved. To elucidate potential mechanisms we used a substrate trap-based assay to identify extracellular-signal-regulated kinase (ERK)1/2 as the predominant substrate of MKP3. Furthermore we also established that brief chemical stabilization of a modified destabilized MKP3 does not alter PKC-mediated down regulation of NET. Finally, the expression of a dominant negative version of H-Ras, an upstream activator of ERK1/2, abolishes phorbol 12-myristate 13-acetate (PMA)-mediated down regulation of NET in a manner similar to MKP3. Taken together we propose that chronic MKP3 expression regulates surface NET through the sustained inhibition of ERK1/2 MAP kinase signaling that alters gene expression in PC12 cells. This is supported by gene expression data from naïve and MKP3-expressing PC12 cells that reveal robust decreases in gene expression of several genes in the MKP3-tranfected cells. Interestingly, caveolin-1, a protein with a critical role in membrane protein trafficking is down regulated by MKP3 expression. We further show that selective silencing of the caveolin-1 gene in naïve PC12 cells attenuates PKC-mediated downregulation of NET activity, consistent with a potential role for caveolins in regulating NET surface expression. In summary, these results suggest that chronic MKP3 expression alters the expression of genes in PC12 cells that are involved in the regulation of NET surface expression.
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Affiliation(s)
- Ole V Mortensen
- Department of Pharmacology and Physiology, Drexel University College of MedicinePhiladelphia, PA, United States
| | - Mads B Larsen
- Department of Cell Biology and Physiology, University of Pittsburgh School of MedicinePittsburgh, PA, United States
| | - Susan G Amara
- National Institute of Mental HealthBethesda, MD, United States
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17
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Li MH, Underhill SM, Reed C, Phillips TJ, Amara SG, Ingram SL. Amphetamine and Methamphetamine Increase NMDAR-GluN2B Synaptic Currents in Midbrain Dopamine Neurons. Neuropsychopharmacology 2017; 42:1539-1547. [PMID: 27976681 PMCID: PMC5436114 DOI: 10.1038/npp.2016.278] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 11/29/2016] [Accepted: 12/11/2016] [Indexed: 02/07/2023]
Abstract
The psychostimulants amphetamine (AMPH) and methamphetamine (MA) are widely abused illicit drugs. Here we show that both psychostimulants acutely increase NMDA receptor (NMDAR)-mediated synaptic currents and decrease AMPA receptor (AMPAR)/NMDAR ratios in midbrain dopamine neurons. The potentiation depends on the transport of AMPH into the cell by the dopamine transporter. NMDAR-GluN2B receptor inhibitors, ifenprodil, RO 25-6981, and RO 04-5595, inhibit the potentiation without affecting basal-evoked NMDA currents, indicating that NMDAR-GluN2B receptors are activated by AMPH. A selective peptide inhibitor of AMPH-dependent trafficking of the neuronal excitatory amino acid transporter 3 (EAAT3) blocks potentiation, suggesting that EAAT3 internalization increases extracellular glutamate concentrations and activates GluN2B-containing NMDARs. Experiments with the use-dependent NMDAR blocker, MK-801, indicate that potentiated NMDARs reside on the plasma membrane and are not inserted de novo. In behavioral studies, GluN2B inhibitors reduce MA-mediated locomotor activity, without affecting basal activity. These results reveal an important interaction between dopamine and glutamatergic signaling in midbrain dopamine neurons in response to acute administration of psychostimulants.
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Affiliation(s)
- Ming-Hua Li
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, USA
| | - Suzanne M Underhill
- National Institute of Mental Health, National Institutes of Health, Laboratory of Molecular and Cellular Neurobiology, Bethesda, MD, USA
| | - Cheryl Reed
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, USA
| | - Tamara J Phillips
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, USA,VA Portland Health Care System, Portland, OR, USA
| | - Susan G Amara
- National Institute of Mental Health, National Institutes of Health, Laboratory of Molecular and Cellular Neurobiology, Bethesda, MD, USA
| | - Susan L Ingram
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, USA,Department of Neurological Surgery, Oregon Health & Science University (OHSU), 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA, Tel: 503 494 1220, Fax: 503 494 2664, E-mail:
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18
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Cheng MH, Torres-Salazar D, Gonzalez-Suarez AD, Amara SG, Bahar I. Substrate transport and anion permeation proceed through distinct pathways in glutamate transporters. eLife 2017; 6. [PMID: 28569666 PMCID: PMC5472439 DOI: 10.7554/elife.25850] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 05/10/2017] [Indexed: 11/13/2022] Open
Abstract
Advances in structure-function analyses and computational biology have enabled a deeper understanding of how excitatory amino acid transporters (EAATs) mediate chloride permeation and substrate transport. However, the mechanism of structural coupling between these functions remains to be established. Using a combination of molecular modeling, substituted cysteine accessibility, electrophysiology and glutamate uptake assays, we identified a chloride-channeling conformer, iChS, transiently accessible as EAAT1 reconfigures from substrate/ion-loaded into a substrate-releasing conformer. Opening of the anion permeation path in this iChS is controlled by the elevator-like movement of the substrate-binding core, along with its wall that simultaneously lines the anion permeation path (global); and repacking of a cluster of hydrophobic residues near the extracellular vestibule (local). Moreover, our results demonstrate that stabilization of iChS by chemical modifications favors anion channeling at the expense of substrate transport, suggesting a mutually exclusive regulation mediated by the movement of the flexible wall lining the two regions.
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Affiliation(s)
- Mary Hongying Cheng
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, United States
| | - Delany Torres-Salazar
- Laboratory of Molecular and Cellular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, United States
| | - Aneysis D Gonzalez-Suarez
- Laboratory of Molecular and Cellular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, United States
| | - Susan G Amara
- Laboratory of Molecular and Cellular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, United States
| | - Ivet Bahar
- Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, United States
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19
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Divito CB, Borowski JE, Glasgow NG, Gonzalez-Suarez AD, Torres-Salazar D, Johnson JW, Amara SG. Glial and Neuronal Glutamate Transporters Differ in the Na + Requirements for Activation of the Substrate-Independent Anion Conductance. Front Mol Neurosci 2017; 10:150. [PMID: 28611584 PMCID: PMC5447070 DOI: 10.3389/fnmol.2017.00150] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 05/04/2017] [Indexed: 01/12/2023] Open
Abstract
Excitatory amino acid transporters (EAATs) are secondary active transporters of L-glutamate and L- or D-aspartate. These carriers also mediate a thermodynamically uncoupled anion conductance that is gated by Na+ and substrate binding. The activation of the anion channel by binding of Na+ alone, however, has only been demonstrated for mammalian EAAC1 (EAAT3) and EAAT4. To date, no difference has been observed for the substrate dependence of anion channel gating between the glial, EAAT1 and EAAT2, and the neuronal isoforms EAAT3, EAAT4 and EAAT5. Here we describe a difference in the Na+-dependence of anion channel gating between glial and neuronal isoforms. Chloride flux through transporters without glutamate binding has previously been described as substrate-independent or "leak" channel activity. Choline or N-methyl-D-glucamine replacement of external Na+ ions significantly reduced or abolished substrate-independent EAAT channel activity in EAAT3 and EAAT4 yet has no effect on EAAT1 or EAAT2. The interaction of Na+ with the neuronal carrier isoforms was concentration dependent, consistent with previous data. The presence of substrate and Na+-independent open states in the glial EAAT isoforms is a novel finding in the field of EAAT function. Our results reveal an important divergence in anion channel function between glial and neuronal glutamate transporters and highlight new potential roles for the EAAT-associated anion channel activity based on transporter expression and localization in the central nervous system.
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Affiliation(s)
- Christopher B Divito
- Center for Neuroscience, Department of Neurobiology, University of PittsburghPittsburgh, PA, United States
| | - Jenna E Borowski
- Center for Neuroscience, Department of Neurobiology, University of PittsburghPittsburgh, PA, United States
| | - Nathan G Glasgow
- Center for Neuroscience, Department of Neuroscience, University of PittsburghPittsburgh, PA, United States
| | - Aneysis D Gonzalez-Suarez
- Laboratory of Cellular and Molecular Neurobiology, National Institute of Mental Health, National Institutes of HealthBethesda, MD, United States
| | - Delany Torres-Salazar
- Laboratory of Cellular and Molecular Neurobiology, National Institute of Mental Health, National Institutes of HealthBethesda, MD, United States
| | - Jon W Johnson
- Center for Neuroscience, Department of Neuroscience, University of PittsburghPittsburgh, PA, United States
| | - Susan G Amara
- Laboratory of Cellular and Molecular Neurobiology, National Institute of Mental Health, National Institutes of HealthBethesda, MD, United States
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20
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Hong WC, Yano H, Hiranita T, Chin FT, McCurdy CR, Su TP, Amara SG, Katz JL. The sigma-1 receptor modulates dopamine transporter conformation and cocaine binding and may thereby potentiate cocaine self-administration in rats. J Biol Chem 2017; 292:11250-11261. [PMID: 28495886 DOI: 10.1074/jbc.m116.774075] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 05/10/2017] [Indexed: 11/06/2022] Open
Abstract
The dopamine transporter (DAT) regulates dopamine (DA) neurotransmission by recapturing DA into the presynaptic terminals and is a principal target of the psychostimulant cocaine. The sigma-1 receptor (σ1R) is a molecular chaperone, and its ligands have been shown to modulate DA neuronal signaling, although their effects on DAT activity are unclear. Here, we report that the prototypical σ1R agonist (+)-pentazocine potentiated the dose response of cocaine self-administration in rats, consistent with the effects of the σR agonists PRE-084 and DTG (1,3-di-o-tolylguanidine) reported previously. These behavioral effects appeared to be correlated with functional changes of DAT. Preincubation with (+)-pentazocine or PRE-084 increased the Bmax values of [3H]WIN35428 binding to DAT in rat striatal synaptosomes and transfected cells. A specific interaction between σ1R and DAT was detected by co-immunoprecipitation and bioluminescence resonance energy transfer assays. Mutational analyses indicated that the transmembrane domain of σ1R likely mediated this interaction. Furthermore, cysteine accessibility assays showed that σ1R agonist preincubation potentiated cocaine-induced changes in DAT conformation, which were blocked by the specific σ1R antagonist CM304. Moreover, σ1R ligands had distinct effects on σ1R multimerization. CM304 increased the proportion of multimeric σ1Rs, whereas (+)-pentazocine increased monomeric σ1Rs. Together these results support the hypothesis that σ1R agonists promote dissociation of σ1R multimers into monomers, which then interact with DAT to stabilize an outward-facing DAT conformation and enhance cocaine binding. We propose that this novel molecular mechanism underlies the behavioral potentiation of cocaine self-administration by σ1R agonists in animal models.
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Affiliation(s)
- Weimin Conrad Hong
- From the Department of Pharmaceutical Sciences, Butler University, Indianapolis, Indiana 46208,
| | - Hideaki Yano
- Intramural Research Program, National Institute on Drug Abuse, Baltimore, Maryland 21224
| | - Takato Hiranita
- Intramural Research Program, National Institute on Drug Abuse, Baltimore, Maryland 21224
| | - Frederick T Chin
- Molecular Imaging Program at Stanford (MIPS), Department of Radiology, Stanford University, Stanford, California 94305
| | - Christopher R McCurdy
- the Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, Florida 32610, and
| | - Tsung-Ping Su
- Intramural Research Program, National Institute on Drug Abuse, Baltimore, Maryland 21224
| | - Susan G Amara
- the Laboratory of Molecular and Cellular Neurobiology, National Institute of Mental Health, Bethesda, Maryland 20892
| | - Jonathan L Katz
- Intramural Research Program, National Institute on Drug Abuse, Baltimore, Maryland 21224
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21
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Torres-Salazar D, Poblete H, Gonzalez-Suarez A, Vergara-Jaque A, Garcia-Olivares J, Comer J, Amara SG. Insights into the Gating Mechanism of Excitatory Amino Acid Transporters-Associated Anion Channel. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.1820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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22
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Insel PA, Amara SG, Blaschke TF, Meyer UA. Introduction to the Theme "New Methods and Novel Therapeutic Approaches in Pharmacology and Toxicology". Annu Rev Pharmacol Toxicol 2017; 57:13-17. [PMID: 27732830 DOI: 10.1146/annurev-pharmtox-091616-023708] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Major advances in scientific discovery and insights can result from the development and use of new techniques, as exemplified by the work of Solomon Snyder, who writes a prefatory article in this volume. The Editors have chosen "New Methods and Novel Therapeutic Approaches in Pharmacology and Toxicology" as the Theme for a number of articles in this volume. These include ones that review the development and use of new experimental tools and approaches (e.g., nanobodies and techniques to explore protein-protein interactions), new types of therapeutics (e.g., aptamers and antisense oligonucleotides), and systems pharmacology, which assembles (big) data derived from omics studies together with information regarding drugs and patients. The application of these new methods and therapeutic approaches has the potential to have a major impact on basic and clinical research in pharmacology and toxicology as well as on patient care.
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Affiliation(s)
- Paul A Insel
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093.,Department of Medicine, University of California, San Diego, La Jolla, California 92093
| | - Susan G Amara
- National Institute of Mental Health, Bethesda, Maryland 20892
| | - Terrence F Blaschke
- Department of Medicine, Stanford University School of Medicine, Stanford, California 94305
| | - Urs A Meyer
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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23
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Abstract
Biogenic amine transporters mediate two important steps in the reuptake and recycling of monoamines released by neurons in the central nervous system. First, high-affinity transporters found in the plasma membrane of neurons and glial cells mediate the removal of neurotransmitter from the extracellular space, thus terminating the action of the monoamines serotonin, norepinephrine, and dopamine. Within the cell, vesicular transporters repackage monoamines into vesicles for additional cycles of release. Two gene families are involved in the transport of the biogenic amines—the Na+/Cl--dependent plasma membrane carriers and the H+-dependent vesicular amine carriers. These transporters are known to regulate neurotransmitter con centrations in monoaminergic pathways and are the primary targets for a wide variety of clinically important antidepressants, antihypertensives, stimulants, and stimulant drugs of abuse. The Neuroscientist 1:259-267, 1995
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Affiliation(s)
- Susan G. Amara
- The Vollum Institute and Howard Hughes Medical Institute
Oregon Health Sciences University Portland, Oregon
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24
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Affiliation(s)
- Delany Torres-Salazar
- a National Institute of Mental Health, National Institutes of Health , Bethesda , ME , USA
| | | | - Susan G Amara
- a National Institute of Mental Health, National Institutes of Health , Bethesda , ME , USA
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25
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Insel PA, Amara SG, Blaschke TF, Meyer UA. Introduction to the Theme "Cancer Pharmacology". Annu Rev Pharmacol Toxicol 2015; 56:19-22. [PMID: 26551200 DOI: 10.1146/annurev-pharmtox-102015-123106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Paul A Insel
- Departments of Pharmacology and Medicine, University of California, San Diego, La Jolla, California 92093
| | - Susan G Amara
- National Institute of Mental Health, Bethesda, Maryland 20892
| | - Terrence F Blaschke
- Departments of Medicine and Molecular Pharmacology, Stanford University School of Medicine, Stanford, California 94305
| | - Urs A Meyer
- Division of Pharmacology and Neurobiology, University of Basel, Basel CH-4056, Switzerland
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26
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Torres-Salazar D, Jiang J, Divito CB, Garcia-Olivares J, Amara SG. A Mutation in Transmembrane Domain 7 (TM7) of Excitatory Amino Acid Transporters Disrupts the Substrate-dependent Gating of the Intrinsic Anion Conductance and Drives the Channel into a Constitutively Open State. J Biol Chem 2015. [PMID: 26203187 DOI: 10.1074/jbc.m115.660860] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In the mammalian central nervous system, excitatory amino acid transporters (EAATs) are responsible for the clearance of glutamate after synaptic release. This energetically demanding activity is crucial for precise neuronal communication and for maintaining extracellular glutamate concentrations below neurotoxic levels. In addition to their ability to recapture glutamate from the extracellular space, EAATs exhibit a sodium- and glutamate-gated anion conductance. Here we show that substitution of a conserved positively charged residue (Arg-388, hEAAT1) in transmembrane domain 7 with a negatively charged amino acid eliminates the ability of glutamate to further activate the anion conductance. When expressed in oocytes, R388D or R388E mutants show large anion currents that display no further increase in amplitude after application of saturating concentrations of Na(+) and glutamate. They also show a substantially reduced transport activity. The mutant transporters appear to exist preferentially in a sodium- and glutamate-independent constitutive open channel state that rarely transitions to complete the transport cycle. In addition, the accessibility of cytoplasmic residues to membrane-permeant modifying reagents supports the idea that this substrate-independent open state correlates with an intermediate outward facing conformation of the transporter. Our data provide additional insights into the mechanism by which substrates gate the anion conductance in EAATs and suggest that in EAAT1, Arg-388 is a critical element for the structural coupling between the substrate translocation and the gating mechanisms of the EAAT-associated anion channel.
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Affiliation(s)
| | - Jie Jiang
- the Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | - Christopher B Divito
- the Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | | | - Susan G Amara
- From the National Institute of Mental Health, Bethesda, Maryland 20892 and the Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
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Torres Salazar D, Garcia-Olivares J, Amara SG. A Mutation in TM7 of Excitatory Amino Acid Transporters Disrupts the Substrate-Dependent Gating of the Intrinsic Anion Conductance and Drives the Channel into a Constitutively Open State. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.2512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Affiliation(s)
- Paul A Insel
- Department of Pharmacology, University of California, San Diego School of Medicine, La Jolla, California 92093;
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Abstract
Excitatory amino acid transporters (EAATs) limit glutamatergic signaling and maintain extracellular glutamate concentrations below neurotoxic levels. Of the five known EAAT isoforms (EAATs 1–5), only the neuronal isoform, EAAT3 (EAAC1), can efficiently transport the uncharged amino acid L-cysteine. EAAT3-mediated cysteine transport has been proposed to be a primary mechanism used by neurons to obtain cysteine for the synthesis of glutathione, a key molecule in preventing oxidative stress and neuronal toxicity. The molecular mechanisms underlying the selective transport of cysteine by EAAT3 have not been elucidated. Here we propose that the transport of cysteine through EAAT3 requires formation of the thiolate form of cysteine in the binding site. Using Xenopus oocytes and HEK293 cells expressing EAAT2 and EAAT3, we assessed the transport kinetics of different substrates and measured transporter-associated currents electrophysiologically. Our results show that L-selenocysteine, a cysteine analog that forms a negatively-charged selenolate ion at physiological pH, is efficiently transported by EAATs 1–3 and has a much higher apparent affinity for transport when compared to cysteine. Using a membrane tethered GFP variant to monitor intracellular pH changes associated with transport activity, we observed that transport of either L-glutamate or L-selenocysteine by EAAT3 decreased intracellular pH, whereas transport of cysteine resulted in cytoplasmic alkalinization. No change in pH was observed when cysteine was applied to cells expressing EAAT2, which displays negligible transport of cysteine. Under conditions that favor release of intracellular substrates through EAAT3 we observed release of labeled intracellular glutamate but did not detect cysteine release. Our results support a model whereby cysteine transport through EAAT3 is facilitated through cysteine de-protonation and that once inside, the thiolate is rapidly re-protonated. Moreover, these findings suggest that cysteine transport is predominantly unidirectional and that reverse transport does not contribute to depletion of intracellular cysteine pools.
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Affiliation(s)
- Spencer D. Watts
- Center for Neuroscience, Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Delany Torres-Salazar
- Laboratory of Cellular and Molecular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Christopher B. Divito
- Center for Neuroscience, Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Susan G. Amara
- Center for Neuroscience, Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Laboratory of Cellular and Molecular Neurobiology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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Underhill SM, Wheeler DS, Li M, Watts SD, Ingram SL, Amara SG. Amphetamine modulates excitatory neurotransmission through endocytosis of the glutamate transporter EAAT3 in dopamine neurons. Neuron 2014; 83:404-416. [PMID: 25033183 DOI: 10.1016/j.neuron.2014.05.043] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/27/2014] [Indexed: 12/15/2022]
Abstract
Amphetamines modify the brain and alter behavior through mechanisms generally attributed to their ability to regulate extracellular dopamine concentrations. However, the actions of amphetamine are also linked to adaptations in glutamatergic signaling. We report here that when amphetamine enters dopamine neurons through the dopamine transporter, it stimulates endocytosis of an excitatory amino acid transporter, EAAT3, in dopamine neurons. Consistent with this decrease in surface EAAT3, amphetamine potentiates excitatory synaptic responses in dopamine neurons. We also show that the process of internalization is dynamin- and Rho-mediated and requires a unique sequence in the cytosolic C terminus of EAAT3. Introduction of a peptide based on this motif into dopamine neurons blocks the effects of amphetamine on EAAT3 internalization and its action on excitatory responses. These data indicate that the internalization of EAAT3 triggered by amphetamine increases glutamatergic signaling and thus contributes to the effects of amphetamine on neurotransmission.
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Affiliation(s)
- Suzanne M Underhill
- Laboratory of Molecular and Cellular Neurobiology, NIH/NIMH, Bethesda, MD 20892, USA.
| | - David S Wheeler
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Minghua Li
- Department of Neurological Surgery, Oregon Health and Science University, Portland, OR 97239, USA
| | - Spencer D Watts
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Susan L Ingram
- Department of Neurological Surgery, Oregon Health and Science University, Portland, OR 97239, USA
| | - Susan G Amara
- Laboratory of Molecular and Cellular Neurobiology, NIH/NIMH, Bethesda, MD 20892, USA; Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15260, USA
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Hong WC, Amara SG. Differential targeting of the dopamine transporter to recycling or degradative pathways during amphetamine- or PKC-regulated endocytosis in dopamine neurons. FASEB J 2013; 27:2995-3007. [PMID: 23612789 DOI: 10.1096/fj.12-218727] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The dopamine transporter (DAT) clears the extracellular dopamine released during neurotransmission and is a major target for both therapeutic and addictive psychostimulant amphetamines. Amphetamine exposure or activation of protein kinase C (PKC) by the phorbol ester PMA has been shown to down-regulate cell surface DAT. However, in dopamine neurons, the trafficking itinerary and fate of internalized DAT has not been elucidated. By monitoring surface-labeled DAT in transfected dopamine neurons from embryonic rat mesencephalic cultures, we find distinct sorting and fates of internalized DAT after amphetamine or PMA treatment. Although both drugs promote DAT internalization above constitutive endocytosis in dopamine neurons, PMA induces ubiquitination of DAT and leads to accumulation of DAT on LAMP1-positive endosomes. In contrast, after amphetamine exposure DAT is sorted to recycling endosomes positive for Rab11 and the transferrin receptor. Furthermore, quantitative assessment of DAT recycling using an antibody-feeding assay reveals that significantly less DAT returns to the surface of dopamine neurons after internalization by PMA, compared with vehicle or amphetamine treatment. These results demonstrate that, in neurons, the DAT is sorted differentially to recycling and degradative pathways after psychostimulant exposure or PKC activation, which may allow for either the transient or sustained inhibition of DAT during dopamine neurotransmission.
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Affiliation(s)
- Weimin C Hong
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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Ingram SL, Li M, Underhill SM, Amara SG. Amphetamine potentiates NMDA receptor currents in midbrain dopamine neurons. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.885.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Susan L. Ingram
- Neurological SurgeryOregon Health & Science UniversityPortlandOR
| | - Minghua Li
- Neurological SurgeryOregon Health & Science UniversityPortlandOR
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Garcia-Olivares J, Torres-Salazar D, Owens WA, Baust T, Siderovski DP, Amara SG, Zhu J, Daws LC, Torres GE. Inhibition of dopamine transporter activity by G protein βγ subunits. PLoS One 2013; 8:e59788. [PMID: 23555781 PMCID: PMC3608556 DOI: 10.1371/journal.pone.0059788] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 02/18/2013] [Indexed: 12/15/2022] Open
Abstract
Uptake through the Dopamine Transporter (DAT) is the primary mechanism of terminating dopamine signaling within the brain, thus playing an essential role in neuronal homeostasis. Deregulation of DAT function has been linked to several neurological and psychiatric disorders including ADHD, schizophrenia, Parkinson’s disease, and drug addiction. Over the last 15 years, several studies have revealed a plethora of mechanisms influencing the activity and cellular distribution of DAT; suggesting that fine-tuning of dopamine homeostasis occurs via an elaborate interplay of multiple pathways. Here, we show for the first time that the βγ subunits of G proteins regulate DAT activity. In heterologous cells and brain tissue, a physical association between Gβγ subunits and DAT was demonstrated by co-immunoprecipitation. Furthermore, in vitro pull-down assays using purified proteins established that this association occurs via a direct interaction between the intracellular carboxy-terminus of DAT and Gβγ. Functional assays performed in the presence of the non-hydrolyzable GTP analog GTP-γ-S, Gβγ subunit overexpression, or the Gβγ activator mSIRK all resulted in rapid inhibition of DAT activity in heterologous systems. Gβγ activation by mSIRK also inhibited dopamine uptake in brain synaptosomes and dopamine clearance from mouse striatum as measured by high-speed chronoamperometry in vivo. Gβγ subunits are intracellular signaling molecules that regulate a multitude of physiological processes through interactions with enzymes and ion channels. Our findings add neurotransmitter transporters to the growing list of molecules regulated by G-proteins and suggest a novel role for Gβγ signaling in the control of dopamine homeostasis.
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Affiliation(s)
- Jennie Garcia-Olivares
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Delany Torres-Salazar
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - William A. Owens
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Tracy Baust
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - David P. Siderovski
- Department of Pharmacology and UNC Neuroscience Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Susan G. Amara
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Jun Zhu
- Department of Pharmaceutical and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina, United States of America
| | - Lynette C. Daws
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Gonzalo E. Torres
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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Landis SC, Amara SG, Asadullah K, Austin CP, Blumenstein R, Bradley EW, Crystal RG, Darnell RB, Ferrante RJ, Fillit H, Finkelstein R, Fisher M, Gendelman HE, Golub RM, Goudreau JL, Gross RA, Gubitz AK, Hesterlee SE, Howells DW, Huguenard J, Kelner K, Koroshetz W, Krainc D, Lazic SE, Levine MS, Macleod MR, McCall JM, Moxley RT, Narasimhan K, Noble LJ, Perrin S, Porter JD, Steward O, Unger E, Utz U, Silberberg SD. A call for transparent reporting to optimize the predictive value of preclinical research. Nature 2012; 490:187-91. [PMID: 23060188 DOI: 10.1038/nature11556] [Citation(s) in RCA: 864] [Impact Index Per Article: 72.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 09/10/2012] [Indexed: 01/02/2023]
Abstract
The US National Institute of Neurological Disorders and Stroke convened major stakeholders in June 2012 to discuss how to improve the methodological reporting of animal studies in grant applications and publications. The main workshop recommendation is that at a minimum studies should report on sample-size estimation, whether and how animals were randomized, whether investigators were blind to the treatment, and the handling of data. We recognize that achieving a meaningful improvement in the quality of reporting will require a concerted effort by investigators, reviewers, funding agencies and journal editors. Requiring better reporting of animal studies will raise awareness of the importance of rigorous study design to accelerate scientific progress.
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Affiliation(s)
- Story C Landis
- National Institute of Neurological Disorders and Stroke, NIH, Bethesda, Maryland 20892, USA
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Watts SD, Suchland KL, Amara SG, Ingram SL. A sensitive membrane-targeted biosensor for monitoring changes in intracellular chloride in neuronal processes. PLoS One 2012; 7:e35373. [PMID: 22506078 PMCID: PMC3323644 DOI: 10.1371/journal.pone.0035373] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 03/15/2012] [Indexed: 01/28/2023] Open
Abstract
Background Regulation of chloride gradients is a major mechanism by which excitability is regulated in neurons. Disruption of these gradients is implicated in various diseases, including cystic fibrosis, neuropathic pain and epilepsy. Relatively few studies have addressed chloride regulation in neuronal processes because probes capable of detecting changes in small compartments over a physiological range are limited. Methodology/Principal Findings In this study, a palmitoylation sequence was added to a variant of the yellow fluorescent protein previously described as a sensitive chloride indicator (YFPQS) to target the protein to the plasma membrane (mbYFPQS) of cultured midbrain neurons. The reporter partitions to the cytoplasmic face of the cellular membranes, including the plasma membrane throughout the neurons and fluorescence is stable over 30–40 min of repeated excitation showing less than 10% decrease in mbYFPQS fluorescence compared to baseline. The mbYFPQS has similar chloride sensitivity (k50 = 41 mM) but has a shifted pKa compared to the unpalmitoylated YFPQS variant (cytYFPQS) that remains in the cytoplasm when expressed in midbrain neurons. Changes in mbYFPQS fluorescence were induced by the GABAA agonist muscimol and were similar in the soma and processes of the midbrain neurons. Amphetamine also increased mbYFPQS fluorescence in a subpopulation of cultured midbrain neurons that was reversed by the selective dopamine transporter (DAT) inhibitor, GBR12909, indicating that mbYFPQS is sensitive enough to detect endogenous DAT activity in midbrain dopamine (DA) neurons. Conclusions/Significance The mbYFPQS biosensor is a sensitive tool to study modulation of intracellular chloride levels in neuronal processes and is particularly advantageous for simultaneous whole-cell patch clamp and live-cell imaging experiments.
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Affiliation(s)
- Spencer D. Watts
- Department of Neurobiology, Medical School, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Katherine L. Suchland
- Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Susan G. Amara
- Department of Neurobiology, Medical School, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Susan L. Ingram
- Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon, United States of America
- * E-mail:
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Hong WC, Amara SG. Membrane cholesterol modulates the outward facing conformation of the dopamine transporter and alters cocaine binding. J Biol Chem 2010; 285:32616-26. [PMID: 20688912 DOI: 10.1074/jbc.m110.150565] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Clearance of synaptically released dopamine is regulated by the plasmalemmal dopamine transporter (DAT), an integral membrane protein that resides within a complex lipid milieu. Here we demonstrate that cholesterol, a major component of the lipid bilayer, can modulate the conformation of DAT and alter cocaine binding to DAT. In striatal synaptosomes and transfected cells, DAT was in cholesterol-rich membrane fractions after mild detergent extraction. After increasing the membrane cholesterol content by treatment of water-soluble cholesterol (cholesterol mixed with methyl-β-cyclodextrin), we observed an increase in DAT binding B(max) values for cocaine analogs [(3)H]WIN35428 and [(125)I]RTI-55, but similar levels of DAT proteins on the cell surface were shown by surface biotinylation assays. Membrane cholesterol addition also markedly enhanced the accessibility of cysteine sulfhydryl moieties in DAT as probed by a membrane-impermeable maleimide-biotin conjugate. We identified cysteine 306, a juxtamembrane residue on transmembrane domain 6 (TM6) of DAT, as the intrinsic residue exhibiting enhanced reactivity. Similar effects on DAT cysteine accessibility and radioligand binding were observed with addition of zinc, a reagent known to promote the outward facing conformation of DAT. Using substituted cysteine mutants on various positions likely to be extracellular, we identified additional residues located on TM1, TM6, TM7, and TM12 of DAT that are sensitive to alterations in the membrane cholesterol content. Our findings in transfected cells and native tissues support the hypothesis that DAT adopts an outward facing conformation in a cholesterol-rich membrane environment, suggesting a novel modulatory role of the surrounding membrane lipid milieu on DAT function.
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Affiliation(s)
- Weimin C Hong
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
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Shrivastava I, Jiang J, Amara SG, Bahar I. Application of Gaussian Network Model to Elucidate Functional Modes of Motion in a Glutamate Transporter. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.3458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Abstract
Neurotransmitter transporters are membrane proteins that serve as key regulators of extracellular neurotransmitter concentrations and have been long viewed as important targets for drug development by the pharmaceutical industry. Although many cellular signaling systems are known to modulate transport activity, much less is known about how transporters communicate with and are regulated by the various components of the lipid sea in which they reside. Variations in lipid content clearly affect the activity of a variety of transport systems, and with advances in techniques for lipid analysis and a clearer vision of carrier structure, this area of research appears poised for major advances.
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Torres-Salazar D, Jiang J, Amara SG. Sulfhydryl Modification Of Cysteine Substitutions In The Second Hairpin Loop (HP2) Alters The Ion Permeation Properties Of The Glutamate Transporter, EAAT1. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.1339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Watts SD, Divito CB, Torres-Salazar D, Amara SG. Probing the Mechanism of Substrate Recognition and Translocation in the Mammalian Glutamate Transporters. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.1340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Shrivastava IH, Jiang J, Amara SG, Bahar I. Time-resolved mechanism of extracellular gate opening and substrate binding in a glutamate transporter. J Biol Chem 2008; 283:28680-90. [PMID: 18678877 PMCID: PMC2568915 DOI: 10.1074/jbc.m800889200] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Glutamate transporters, also referred to as excitatory amino acid
transporters (EAATs), are membrane proteins that regulate glutamatergic signal
transmission by clearing excess glutamate after its release at synapses. A
structure-based understanding of their molecular mechanisms of function has
been elusive until the recent determination of the x-ray structure of an
archaeal transporter, GltPh. GltPh exists as a trimer,
with each subunit containing a core region that mediates substrate
translocation. In the present study a series of molecular dynamics simulations
have been conducted and analyzed in light of new experimental data on
substrate binding properties of EAATs. The simulations provide for the first
time a full atomic description of the time-resolved events that drive the
recognition and binding of substrate. The core region of each subunit exhibits
an intrinsic tendency to open the helical hairpin HP2 loop, the extracellular
gate, within tens of nanoseconds exposing conserved polar residues that serve
as attractors for substrate binding. The NMDGT motif on the partially unwound
part of the transmembrane helix TM7 and the residues Asp-390 and Asp-394 on
TM8 are also distinguished by their important role in substrate binding and
close interaction with mediating water molecules and/or sodium ions. The
simulations reveal a Na+ binding site comprised in part of Leu-303
on TM7 and Asp-405 on TM8 and support a role for sodium ions in stabilizing
substrate-bound conformers. The functional importance of Leu-303 or its
counterpart Leu-391 in human EAAT1 (hEAAT1) is confirmed by site-directed
mutagenesis and Na+ dependence assays conducted with hEAAT1 mutants
L391C and L391A.
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Affiliation(s)
- Indira H Shrivastava
- Department of Computational Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
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Mortensen OV, Larsen MB, Prasad BM, Amara SG. Genetic complementation screen identifies a mitogen-activated protein kinase phosphatase, MKP3, as a regulator of dopamine transporter trafficking. Mol Biol Cell 2008; 19:2818-29. [PMID: 18434601 DOI: 10.1091/mbc.e07-09-0980] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The antidepressant and cocaine sensitive plasma membrane monoamine transporters are the primary mechanism for clearance of their respective neurotransmitters and serve a pivotal role in limiting monoamine neurotransmission. To identify molecules in pathways that regulate dopamine transporter (DAT) internalization, we used a genetic complementation screen in Xenopus oocytes to identify a mitogen-activated protein (MAP) kinase phosphatase, MKP3/Pyst1/DUSP6, as a molecule that inhibits protein kinase C-induced (PKC) internalization of transporters, resulting in enhanced DAT activity. The involvement of MKP3 in DAT internalization was verified using both overexpression and shRNA knockdown strategies in mammalian cell models including a dopaminergic cell line. Although the isolation of MKP3 implies a role for MAP kinases in DAT internalization, MAP kinase inhibitors have no effect on internalization. Moreover, PKC-dependent down-regulation of DAT does not correlate with the phosphorylation state of several well-studied MAP kinases (ERK1/2, p38, and SAPK/JNK). We also show that MKP3 does not regulate PKC-induced ubiquitylation of DAT but acts at a more downstream step to stabilize DAT at the cell surface by blocking dynamin-dependent internalization and delaying the targeting of DAT for degradation. These results indicate that MKP3 can act to enhance DAT function and identifies MKP3 as a phosphatase involved in regulating dynamin-dependent endocytosis.
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Affiliation(s)
- Ole Valente Mortensen
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
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Fontana ACK, de Oliveira Beleboni R, Wojewodzic MW, Ferreira Dos Santos W, Coutinho-Netto J, Grutle NJ, Watts SD, Danbolt NC, Amara SG. Enhancing glutamate transport: mechanism of action of Parawixin1, a neuroprotective compound from Parawixia bistriata spider venom. Mol Pharmacol 2007; 72:1228-37. [PMID: 17646426 DOI: 10.1124/mol.107.037127] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Previous studies have shown that a compound purified from the spider Parawixia bistriata venom stimulates the activity of glial glutamate transporters and can protect retinal tissue from ischemic damage. To understand the mechanism by which this compound enhances transport, we examined its effects on the functional properties of glutamate transporters after solubilization and reconstitution in liposomes and in transfected COS-7 cells. Here, we demonstrate in both systems that Parawixin1 promotes a direct and selective enhancement of glutamate influx by the EAAT2 transporter subtype through a mechanism that does not alter the apparent affinities for the cosubstrates glutamate or sodium. In liposomes, we observed maximal enhancement by Parawixin1 when extracellular sodium and intracellular potassium concentrations are within physiological ranges. Moreover, the compound does not enhance the reverse transport of glutamate under ionic conditions that favor efflux, when extracellular potassium is elevated and the sodium gradient is reduced, nor does it alter the exchange of glutamate in the absence of internal potassium. These observations suggest that Parawixin1 facilitates the reorientation of the potassium-bound transporter, the rate-limiting step in the transport cycle, a conclusion further supported by experiments showing that Parawixin1 does not stimulate uptake by an EAAT2 transport mutant (E405D) defective in the potassium-dependent reorientation step. Thus, Parawixin1 enhances transport through a novel mechanism targeting a step in the transport cycle distinct from substrate influx or efflux and provides a basis for the design of new drugs that act allosterically on transporters to increase glutamate clearance.
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Abstract
Neurotransmitters are rapidly removed from the extracellular space primarily through the actions of plasma membrane transporters. This uptake process is not only essential in the termination of neurotransmission but also serves to replenish intracellular levels of transmitter for further release. Neurotransmitter transporters couple the inward movement of substrate to the movement of Na(+) down a concentration gradient and, in addition to their transport function, some carriers also display channel-like activities. Five Na(+)/K(+)-dependent glutamate transporter subtypes belong to the solute carrier 1 (SLC1) family and a second family, SLC6, encompasses the Na(+)/Cl(-)-dependent transporters for dopamine, 5-hydroxytryptamine (serotonin), noradrenaline, GABA and glycine. Recent advances, including high-resolution structures from both families, are now providing new insights into the molecular determinants that contribute to substrate translocation and ion channel activities. Other influential studies have explored how cellular regulatory mechanisms modulate transporter function, and how the different functions of the carrier shape the patterns of neurotransmitter signaling. This review focuses on recent studies of glutamate and monoamine transporters as prototypes of the two carrier families.
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Affiliation(s)
- Gonzalo E Torres
- Department of Neurobiology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, Pittsburgh, PA 15261, USA
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Cecchini AL, Vasconcelos F, Amara SG, Giglio JR, Arantes EC. Effects of Tityus serrulatus scorpion venom and its toxin TsTX-V on neurotransmitter uptake in vitro. Toxicol Appl Pharmacol 2006; 217:196-203. [PMID: 17049577 DOI: 10.1016/j.taap.2006.09.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2006] [Revised: 08/31/2006] [Accepted: 09/04/2006] [Indexed: 11/29/2022]
Abstract
Scorpion neurotoxins targeting the Na(v) channel can be classified into two classes: alpha- and beta-neurotoxins and are reported as highly active in mammalian brain. In this work, we evaluate the effects of Tityus serrulatus venom (Ts venom) and its alpha-neurotoxin TsTX-V on gamma-aminobutyric acid (GABA), dopamine (DA) and glutamate (Glu) uptake in isolated rat brain synaptosomes. TsTX-V was isolated from Ts venom by ion exchange chromatography followed by reverse-phase (C18) high-performance liquid chromatography. Neither Ts venom nor TsTX-V was able to affect (3)H-Glu uptake. On the other hand, Ts venom (0.13 microg/mg) significantly inhibited both (3)H-GABA and (3)H-DA uptake ( approximately 50%). TsTX-V showed IC(50) values of 9.37 microM and 22.2 microM for the inhibition of (3)H-GABA and (3)H-DA uptake, respectively. These effects were abolished by pre-treatment with tetrodotoxin (TTX, 1 microM), indicating the involvement of voltage-gated Na(+) channels in this process. In the absence of Ca(2+), and at low Ts venom concentrations, the reduction of (3)H-GABA uptake was not as marked as in the presence of Ca(2+). TsTX-V did not reduce (3)H-GABA uptake in COS-7 cells expressing the GABA transporters GAT-1 and GAT-3, suggesting that this toxin indirectly reduces the transport. The reduced (3)H-GABA uptake by synaptosomes might be due to rapid cell depolarization as revealed by confocal microscopy of C6 glioma cells. Thus, TsTX-V causes a reduction of (3)H-GABA and (3)H-DA uptake in a Ca(2+)-dependent manner, not directly affecting GABA transporters, but, in consequence of depolarization, involving voltage-gated Na(+) channels.
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Affiliation(s)
- Alessandra L Cecchini
- Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto-USP, Av. do Café, s/n, 14040-903, Ribeirão Preto-SP, Brazil
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Leighton BH, Seal RP, Watts SD, Skyba MO, Amara SG. Structural Rearrangements at the Translocation Pore of the Human Glutamate Transporter, EAAT1. J Biol Chem 2006; 281:29788-96. [PMID: 16877378 DOI: 10.1074/jbc.m604991200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Structure-function studies of mammalian and bacterial excitatory amino acid transporters (EAATs), as well as the crystal structure of a related archaeal glutamate transporter, support a model in which TM7, TM8, and the re-entrant loops HP1 and HP2 participate in forming a substrate translocation pathway within each subunit of a trimer. However, the transport mechanism, including precise binding sites for substrates and co-transported ions and changes in the tertiary structure underlying transport, is still not known. In this study, we used chemical cross-linking of introduced cysteine pairs in a cysteine-less version of EAAT1 to examine the dynamics of key domains associated with the translocation pore. Here we show that cysteine substitution at Ala-395, Ala-367, and Ala-440 results in functional single and double cysteine transporters and that in the absence of glutamate or dl-threo-beta-benzyloxyaspartate (dl-TBOA), A395C in the highly conserved TM7 can be cross-linked to A367C in HP1 and to A440C in HP2. The formation of these disulfide bonds is reversible and occurs intra-molecularly. Interestingly, cross-linking A395C to A367C appears to abolish transport, whereas cross-linking A395C to A440C lowers the affinities for glutamate and dl-TBOA but does not change the maximal transport rate. Additionally, glutamate and dl-TBOA binding prevent cross-linking in both double cysteine transporters, whereas sodium binding facilitates cross-linking in the A395C/A367C transporter. These data provide evidence that within each subunit of EAAT1, Ala-395 in TM7 resides close to a residue at the tip of each re-entrant loop (HP1 and HP2) and that these residues are repositioned relative to one another at different steps in the transport cycle. Such behavior likely reflects rearrangements in the tertiary structure of the translocation pore during transport and thus provides constraints for modeling the structural dynamics associated with transport.
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Affiliation(s)
- Barbara H Leighton
- Howard Hughes Medical Institute, Vollum Institute, Oregon Health and Science University, Portland, Oregon 97201, USA
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Mortensen OV, Amara SG. Gain of function mutants reveal sites important for the interaction of the atypical inhibitors benztropine and bupropion with monoamine transporters. J Neurochem 2006; 98:1531-40. [PMID: 16923164 DOI: 10.1111/j.1471-4159.2006.04060.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two atypical inhibitors of the dopamine transporter, benztropine, used in the treatment of Parkinson's disease, and bupropion, used as an antidepressant, show very different psychostimulant effects when compared with another inhibitor, cocaine. Taking advantage of the differential sensitivity of the dopamine and the norepinephrine transporters (DAT and NET) to benztropine and bupropion, we have used site-directed mutagenesis to produce gain-of-function mutants in NET which demonstrate that Ala279 in the trans-membrane domain 5 (TM5) and Ser359 in the TM7 of DAT are responsible for the higher sensitivity of DAT to both bupropion and benztropine. Substitution of these two DAT residues into the NET background does not alter the potency of NET-selective inhibitors, such as desipramine. The results from experiments examining the ability of DAT-selective inhibitors to displace [3H]nisoxetine binding in NET gain-of-function mutants suggest that Ser359 contributes to the initial binding of the inhibitor, and that Ala279 may influence subsequent steps involved in the blockade of translocation. Thus, these studies begin to identify residues that are important for the unique molecular interactions of benztropine and bupropion with the DAT, and that ultimately may contribute to the distinct behavioral actions of these drugs.
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Affiliation(s)
- Ole V Mortensen
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
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Freeman WM, Brebner K, Amara SG, Reed MS, Pohl J, Phillips AG. Distinct proteomic profiles of amphetamine self-administration transitional states. Pharmacogenomics J 2005; 5:203-14. [PMID: 15852055 DOI: 10.1038/sj.tpj.6500309] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the rat, continuous access to d-amphetamine (d-AMPH) leads to lengthy bouts of self-administration, voluntary abstinence, and relapse to self-administration. Previous studies have revealed that the progression from psychostimulant self-administration to abstinence to relapse is mediated in part by the ventral hippocampus. Stimulation of the ventral subiculum (vSub) during voluntary abstinence from d-AMPH self-administration reinstates self-administration and increases nucleus accumbens (NAc) dopamine efflux. Quantitative proteomic examination of the hippocampus from rats naive to amphetamine, during a self-administration session 'Binge', during voluntarily abstinence 'Abstinent', and after reinstatement of self-administration 'Relapse', revealed a differential proteomic state during abstinence. Actin- and cytoskeletal-related proteins were over-represented in the changes occurring during abstinence and suggest a decrease in actin filament polymerization. These changes may underlie alterations in neuronal tone during abstinence that could affect both neurotransmission and behavior. These data provide the first classification of addiction-related behaviors based on clustering of quantitative proteomic measurements. .
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Affiliation(s)
- W M Freeman
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, USA.
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Susarla BTS, Seal RP, Zelenaia O, Watson DJ, Wolfe JH, Amara SG, Robinson MB. Differential regulation of GLAST immunoreactivity and activity by protein kinase C: evidence for modification of amino and carboxyl termini. J Neurochem 2005; 91:1151-63. [PMID: 15569258 DOI: 10.1111/j.1471-4159.2004.02791.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Many neurotransmitter transporters, including the GLT-1 and EAAC1 subtypes of the glutamate transporter, are regulated by protein kinase C (PKC) and these effects are associated with changes in cell surface expression. In the present study, the effects of PKC activation on the glutamate aspartate transporter (GLAST) subtype of glutamate transporter were examined in primary astrocyte cultures. Acute (30 min) exposure to the phorbol 12-myristate 13-acetate (PMA) increased (approximately 20%) transport activity but had the opposite effect on both total and cell surface immunoreactivity. Chronic treatment (6 or 24 h) with PMA had no effect on transport activity but caused an even larger decrease in total and cell surface immunoreactivity. This loss of immunoreactivity was observed using antibodies directed against three different cytoplasmic epitopes, and was blocked by the PKC antagonist, bisindolylmaleimide II. We provide biochemical and pharmacological evidence that the activity observed after treatment with PMA is mediated by GLAST. Two different flag-tagged variants of the human homolog of GLAST were introduced into astrocytes using lentiviral vectors. Although treatment with PMA caused a loss of transporter immunoreactivity, flag immunoreactivity did not change in amount or size. Together, these studies suggest that activation of PKC acutely up-regulates GLAST activity, but also results in modification of several different intracellular epitopes so that they are no longer recognized by anti-GLAST antibodies. We found that exposure of primary cultures of neurons/astrocytes to transient hypoxia/glucose deprivation also caused a loss of GLAST immunoreactivity that was attenuated by the PKC antagonist, bisindolylmaleimide II, suggesting that some acute insults previously thought to cause a loss of GLAST protein may mimic the phenomenon observed in the present study.
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Affiliation(s)
- Bala T S Susarla
- Department of Pediatrics, University of Pennsylvania and Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
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