51
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Reisinger SN, Kong E, Molz B, Humberg T, Sideromenos S, Cicvaric A, Steinkellner T, Yang J, Cabatic M, Monje FJ, Sitte HH, Nichols BJ, Pollak DD. Flotillin-1 interacts with the serotonin transporter and modulates chronic corticosterone response. GENES, BRAIN, AND BEHAVIOR 2019; 18:e12482. [PMID: 29667320 PMCID: PMC6392109 DOI: 10.1111/gbb.12482] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Revised: 04/05/2018] [Accepted: 04/12/2018] [Indexed: 01/08/2023]
Abstract
Aberrant serotonergic neurotransmission in the brain is considered at the core of the pathophysiological mechanisms involved in neuropsychiatric disorders. Gene by environment interactions contribute to the development of depression and involve modulation of the availability and functional activity of the serotonin transporter (SERT). Using behavioral and in vivo electrophysiological approaches together with biochemical, molecular-biological and molecular imaging tools we establish Flotillin-1 (Flot1) as a novel protein interacting with SERT and demonstrate its involvement in the response to chronic corticosterone (CORT) treatment. We show that genetic Flot1 depletion augments chronic CORT-induced behavioral despair and describe concomitant alterations in the expression of SERT, activity of serotonergic neurons and alterations of the glucocorticoid receptor transport machinery. Hence, we propose a role for Flot1 as modulatory factor for the depressogenic consequences of chronic CORT exposure and suggest Flotillin-1-dependent regulation of SERT expression and activity of serotonergic neurotransmission at the core of the molecular mechanisms involved.
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Affiliation(s)
- S. N. Reisinger
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - E. Kong
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - B. Molz
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - T. Humberg
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - S. Sideromenos
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - A. Cicvaric
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - T. Steinkellner
- Department of PharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - J.‐W. Yang
- Department of PharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - M. Cabatic
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - F. J. Monje
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | - H. H. Sitte
- Department of PharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
| | | | - D. D. Pollak
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaViennaAustria
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52
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Das AK, Kudlacek O, Baumgart F, Jaentsch K, Stockner T, Sitte HH, Schütz GJ. Dopamine transporter forms stable dimers in the live cell plasma membrane in a phosphatidylinositol 4,5-bisphosphate-independent manner. J Biol Chem 2019; 294:5632-5642. [PMID: 30705091 PMCID: PMC6462504 DOI: 10.1074/jbc.ra118.006178] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 01/28/2019] [Indexed: 01/01/2023] Open
Abstract
The human dopamine transporter (hDAT) regulates the level of the neurotransmitter dopamine (DA) in the synaptic cleft and recycles DA for storage in the presynaptic vesicular pool. Many neurotransmitter transporters exist as oligomers, but the physiological role of oligomerization remains unclear; for example, it has been speculated to be a prerequisite for amphetamine-induced release and protein trafficking. Previous studies point to an oligomeric quaternary structure of hDAT; however, the exact stoichiometry and the fraction of co-existing oligomeric states are not known. Here, we used single-molecule brightness analysis to quantify the degree of oligomerization of heterologously expressed hDAT fused to monomeric GFP (mGFP–hDAT) in Chinese hamster ovary (CHO) cells. We observed that monomers and dimers of mGFP–hDAT co-exist and that higher-order molecular complexes of mGFP–hDAT are absent at the plasma membrane. The mGFP–hDAT dimers were stable over several minutes, and the fraction of dimers was independent of the mGFP–hDAT surface density. Furthermore, neither oxidation nor depletion of cholesterol had any effect on the fraction of dimers. Unlike for the human serotonin transporter (hSERT), in which direct binding of phosphatidylinositol 4,5-bisphosphate (PIP2) stabilized the oligomers, the stability of mGFP–hDAT dimers was PIP2 independent.
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Affiliation(s)
- Anand Kant Das
- From the Institute of Applied Physics, TU Wien, Getreidemarkt 9, A-1060, Vienna and
| | - Oliver Kudlacek
- the Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Florian Baumgart
- From the Institute of Applied Physics, TU Wien, Getreidemarkt 9, A-1060, Vienna and
| | - Kathrin Jaentsch
- the Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Thomas Stockner
- the Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Harald H Sitte
- the Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University Vienna, Waehringerstrasse 13a, A-1090 Vienna, Austria
| | - Gerhard J Schütz
- From the Institute of Applied Physics, TU Wien, Getreidemarkt 9, A-1060, Vienna and
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53
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Shin EJ, Dang DK, Hwang YG, Tran HQ, Sharma N, Jeong JH, Jang CG, Nah SY, Nabeshima T, Yoneda Y, Cadet JL, Kim HC. Significance of protein kinase C in the neuropsychotoxicity induced by methamphetamine-like psychostimulants. Neurochem Int 2019; 124:162-170. [PMID: 30654115 DOI: 10.1016/j.neuint.2019.01.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 12/27/2018] [Accepted: 01/14/2019] [Indexed: 02/06/2023]
Abstract
The abuse of methamphetamine (MA), an amphetamine (AMPH)-type stimulant, has been demonstrated to be associated with various neuropsychotoxicity, including memory impairment, psychiatric morbidity, and dopaminergic toxicity. Compelling evidence from preclinical studies has indicated that protein kinase C (PKC), a large family of serine/threonine protein kinases, plays an important role in MA-induced neuropsychotoxicity. PKC-mediated N-terminal phosphorylation of dopamine transporter has been identified as one of the prerequisites for MA-induced synaptic dopamine release. Consistently, it has been shown that PKC is involved in MA (or AMPH)-induced memory impairment and mania-like behaviors as well as MA drug dependence. Direct or indirect regulation of factors related to neuronal plasticity seemed to be critical for these actions of PKC. In addition, PKC-mediated mitochondrial dysfunction, oxidative stress or impaired antioxidant defense system has been suggested to play a role in psychiatric and cognitive disturbance induced by MA (or AMPH). In MA-induced dopaminergic toxicity, particularly PKCδ has been shown to trigger oxidative stress, mitochondrial dysfunction, pro-apoptotic changes, and neuroinflammation. Importantly, PKCδ may be a key mediator in the positive feedback loop composed of these detrimental events to potentiate MA-induced dopaminergic toxicity. This review outlines the role of PKC and its individual isozymes in MA-induced neuropsychotoxicity. Better understanding on the molecular mechanism of PKCs might provide a great insight for the development of potential therapeutic or preventive candidates for MA (or AMPH)-associated neuropsychotoxicity.
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Affiliation(s)
- Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea
| | - Duy-Khanh Dang
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea
| | - Young Gwang Hwang
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea
| | - Hai-Quyen Tran
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea
| | - Naveen Sharma
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea
| | - Ji Hoon Jeong
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Choon-Gon Jang
- Department of Pharmacology, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Seung-Yeol Nah
- Ginsentology Research Laboratory and Department of Physiology, College of Veterinary Medicine, Konkuk University, Seoul 05029, Republic of Korea
| | - Toshitaka Nabeshima
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Science, Toyoake 470-1192, Japan
| | - Yukio Yoneda
- Section of Prophylactic Pharmacology, Kanazawa University Venture Business Laboratory, Kanazawa, Ishikawa 920-1192, Japan
| | - Jean Lud Cadet
- NIDA Intramural Program, Molecular Neuropsychiatry Research Branch, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea.
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54
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Hasenhuetl PS, Bhat S, Freissmuth M, Sandtner W. Functional Selectivity and Partial Efficacy at the Monoamine Transporters: A Unified Model of Allosteric Modulation and Amphetamine-Induced Substrate Release. Mol Pharmacol 2018; 95:303-312. [PMID: 30567955 DOI: 10.1124/mol.118.114793] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 12/13/2018] [Indexed: 12/13/2022] Open
Abstract
All clinically approved drugs targeting the plasmalemmal transporters for dopamine, norepinephrine, and serotonin act either as competitive uptake inhibitors or as amphetamine-like releasers. Monoamine transporter (MAT) ligands that allosterically affect MAT-mediated substrate uptake, release, or both were recently discovered. Their modes of action have not yet been explained in a unified framework. Here, we go beyond competitive inhibitors and classic amphetamines and introduce concepts for partial efficacy at and allosteric modulation of MATs. After we elaborate on a kinetic account for amphetamine action, we provide an explanation for partial release (i.e., the observation that some amphetamines are less efficacious than others in inducing monoamine efflux). We then elucidate mechanisms of allosteric inhibition and stimulation of MATs, which can be functionally selective for either substrate uptake or amphetamine-induced release. These concepts are integrated into a parsimonious kinetic framework, which relies exclusively on physiologic transport modes (without any deviation from an alternating access mechanism). The model posits cooperative substrate and Na+ binding and functional selectivity by conformational selection (i.e., preference of the allosteric modulators for the substrate-loaded or substrate-free states of the transporter). Thus, current knowledge about the kinetics of monoamine transport is sufficiently detailed to provide a quantitative description of the releasing action of amphetamines, of substrate uptake, and of selective modulation thereof by allosteric modulators.
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Affiliation(s)
- Peter S Hasenhuetl
- Institute of Pharmacology, Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Shreyas Bhat
- Institute of Pharmacology, Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology, Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Walter Sandtner
- Institute of Pharmacology, Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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55
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Jaykumar AB, Caceres PS, King-Medina KN, Liao TD, Datta I, Maskey D, Naggert JK, Mendez M, Beierwaltes WH, Ortiz PA. Role of Alström syndrome 1 in the regulation of blood pressure and renal function. JCI Insight 2018; 3:95076. [PMID: 30385718 DOI: 10.1172/jci.insight.95076] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 09/26/2018] [Indexed: 01/22/2023] Open
Abstract
Elevated blood pressure (BP) and renal dysfunction are complex traits representing major global health problems. Single nucleotide polymorphisms identified by genome-wide association studies have identified the Alström syndrome 1 (ALMS1) gene locus to render susceptibility for renal dysfunction, hypertension, and chronic kidney disease (CKD). Mutations in the ALMS1 gene in humans causes Alström syndrome, characterized by progressive metabolic alterations including hypertension and CKD. Despite compelling genetic evidence, the underlying biological mechanism by which mutations in the ALMS1 gene lead to the above-mentioned pathophysiology is not understood. We modeled this effect in a KO rat model and showed that ALMS1 genetic deletion leads to hypertension. We demonstrate that the link between ALMS1 and hypertension involves the activation of the renal Na+/K+/2Cl- cotransporter NKCC2, mediated by regulation of its endocytosis. Our findings establish a link between the genetic susceptibility to hypertension, CKD, and the expression of ALMS1 through its role in a salt-reabsorbing tubular segment of the kidney. These data point to ALMS1 as a potentially novel gene involved in BP and renal function regulation.
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Affiliation(s)
- Ankita Bachhawat Jaykumar
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan, USA.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Paulo S Caceres
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan, USA.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Keyona N King-Medina
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan, USA.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Tang-Dong Liao
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan, USA
| | - Indrani Datta
- Department of Public Health Sciences and.,Center for Bioinformatics, Henry Ford Health System, Detroit, Michigan, USA
| | - Dipak Maskey
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan, USA
| | | | - Mariela Mendez
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan, USA
| | - William H Beierwaltes
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan, USA.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Pablo A Ortiz
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan, USA.,Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA
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56
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Liu JJ, Hezghia A, Shaikh SR, Cenido JF, Stark RE, Mann JJ, Sublette ME. Regulation of monoamine transporters and receptors by lipid microdomains: implications for depression. Neuropsychopharmacology 2018; 43:2165-2179. [PMID: 30022062 PMCID: PMC6135777 DOI: 10.1038/s41386-018-0133-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 05/24/2018] [Accepted: 06/18/2018] [Indexed: 12/16/2022]
Abstract
Lipid microdomains ("rafts") are dynamic, nanoscale regions of the plasma membrane enriched in cholesterol and glycosphingolipids, that possess distinctive physicochemical properties including higher order than the surrounding membrane. Lipid microdomain integrity is thought to affect neurotransmitter signaling by regulating membrane-bound protein signaling. Among the proteins potentially affected are monoaminergic receptors and transporters. As dysfunction of monoaminergic neurotransmission is implicated in major depressive disorder and other neuropsychiatric conditions, interactions with lipid microdomains may be of clinical importance. This systematic review evaluates what is known about the molecular relationships of monoamine transporter and receptor regulation to lipid microdomains. The PubMed/MeSH database was searched for original studies published in English through August 2017 concerning relationships between lipid microdomains and serotonin, dopamine and norepinephrine transporters and receptors. Fifty-seven publications were identified and assessed. Strong evidence implicates lipid microdomains in the regulation of serotonin and norepinephrine transporters; serotonin 1A, 2A, 3A, and 7A receptors; and dopamine D1 and β2 adrenergic receptors. Results were conflicting or more complex regarding lipid microdomain associations with the dopamine transporter, D2, D3, and D5 receptors; and negative with respect to β1 adrenergic receptors. Indirect evidence suggests that antidepressants, lipid-lowering drugs, and polyunsaturated fatty acids may exert effects on depression and suicide by altering the lipid milieu, thereby affecting monoaminergic transporter and receptor signaling. The lipid composition of membrane subdomains is involved in localization and trafficking of specific monoaminergic receptors and transporters. Elucidating precise mechanisms whereby lipid microdomains modulate monoamine neurotransmission in clinical contexts can have critical implications for pharmacotherapeutic targeting.
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Affiliation(s)
- Joanne J Liu
- Department of Molecular Imaging & Neuropathology, New York State Psychiatric Institute, New York, NY, USA
- Chestnut Hill Hospital, Philadelphia, PA, USA
| | - Adrienne Hezghia
- Department of Molecular Imaging & Neuropathology, New York State Psychiatric Institute, New York, NY, USA
- Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Saame Raza Shaikh
- Department of Nutrition, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Joshua F Cenido
- Department of Molecular Imaging & Neuropathology, New York State Psychiatric Institute, New York, NY, USA
- Department of Psychiatry, Charles R. Drew University of Medicine and Science, Los Angeles, CA, USA
| | - Ruth E Stark
- Department of Chemistry and Biochemistry and CUNY Institute for Macromolecular Assemblies, The City College of New York, New York, NY, USA
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, NY, USA
| | - J John Mann
- Department of Molecular Imaging & Neuropathology, New York State Psychiatric Institute, New York, NY, USA
- Department of Psychiatry, Columbia University, New York, NY, USA
- Department of Radiology, Columbia University, New York, NY, USA
| | - M Elizabeth Sublette
- Department of Molecular Imaging & Neuropathology, New York State Psychiatric Institute, New York, NY, USA.
- Department of Psychiatry, Columbia University, New York, NY, USA.
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57
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Liu XX, Liu WD, Wang L, Zhu B, Shi X, Peng ZX, Zhu HC, Liu XD, Zhong MZ, Xie D, Zeng MS, Ren CP. Roles of flotillins in tumors. J Zhejiang Univ Sci B 2018; 19:171-182. [PMID: 29504311 DOI: 10.1631/jzus.b1700102] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The identification and use of molecular biomarkers have greatly improved the diagnosis and treatment of malignant tumors. However, a much deeper understanding of oncogenic proteins is needed for the benefit to cancer patients. The lipid raft marker proteins, flotillin-1 and flotillin-2, were first found in goldfish retinal ganglion cells during axon regeneration. They have since been found in a variety of cells, mainly on the inner surface of cell membranes, and not only act as a skeleton to provide a platform for protein-protein interactions, but also are involved in signal transduction, nerve regeneration, endocytosis, and lymphocyte activation. Previous studies have shown that flotillins are closely associated with tumor development, invasion, and metastasis. In this article, we review the functions of flotillins in relevant cell processes, their underlying mechanisms of action in a variety of tumors, and their potential applications to tumor molecular diagnosis and targeted therapy.
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Affiliation(s)
- Xu-Xu Liu
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, Central South University, Changsha 410078, China
| | - Wei-Dong Liu
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, Central South University, Changsha 410078, China
| | - Lei Wang
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, Central South University, Changsha 410078, China
| | - Bin Zhu
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, Central South University, Changsha 410078, China
| | - Xiao Shi
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, Central South University, Changsha 410078, China
| | - Zi-Xuan Peng
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, Central South University, Changsha 410078, China
| | - He-Cheng Zhu
- Changsha Kexin Cancer Hospital, Changsha 410205, China
| | - Xing-Dong Liu
- Changsha Kexin Cancer Hospital, Changsha 410205, China
| | - Mei-Zuo Zhong
- Changsha Kexin Cancer Hospital, Changsha 410205, China
| | - Dan Xie
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou 510060, China
| | - Mu-Sheng Zeng
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou 510060, China
| | - Cai-Ping Ren
- Cancer Research Institute, Collaborative Innovation Center for Cancer Medicine, Key Laboratory for Carcinogenesis of Chinese Ministry of Health, Central South University, Changsha 410078, China
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58
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Hovde MJ, Larson GH, Vaughan RA, Foster JD. Model systems for analysis of dopamine transporter function and regulation. Neurochem Int 2018; 123:13-21. [PMID: 30179648 DOI: 10.1016/j.neuint.2018.08.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 08/23/2018] [Accepted: 08/31/2018] [Indexed: 02/07/2023]
Abstract
The dopamine transporter (DAT) plays a critical role in dopamine (DA) homeostasis by clearing transmitter from the extraneuronal space after vesicular release. DAT serves as a site of action for a variety of addictive and therapeutic reuptake inhibitors, and transport dysfunction is associated with transmitter imbalances in disorders such as schizophrenia, attention deficit hyperactive disorder, bipolar disorder, and Parkinson disease. In this review, we describe some of the model systems that have been used for in vitro analyses of DAT structure, function and regulation, and discuss a potential relationship between transporter kinetic values and membrane cholesterol.
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Affiliation(s)
- Moriah J Hovde
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND, 58202, USA
| | - Garret H Larson
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND, 58202, USA
| | - Roxanne A Vaughan
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND, 58202, USA
| | - James D Foster
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND, 58202, USA.
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59
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Guo AY, Liang XJ, Liu RJ, Li XX, Bi W, Zhou LY, Tang CE, Yan A, Chen ZC, Zhang PF. Flotilin-1 promotes the tumorigenicity and progression of malignant phenotype in human lung adenocarcinoma. Cancer Biol Ther 2018; 18:715-722. [PMID: 28825855 DOI: 10.1080/15384047.2017.1360445] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Lung adenocarcinoma (LUAD) accounts for the most common histological subtype of lung cancer which remains the leading cause of cancer death worldwide. The discovery of more sensitive and specific novel target biomarkers for predicting the development and progression of LUAD is imperative. Flotillin-1 (Flot-1) has been reported to have important roles in the progression of several tumor types but not been reported in the progression of LUAD. Here, we demonstrated that the expression of flotillin-1 was upregulated in 5 LUAD cells. Moreover, multiple approaches were used to explore the tumorigenicity of flotillin-1 in LUAD cell lines. The expression levels of flotillin-1 were analyzed by immunoblotting after overexpression and siRNA-based knockdown. Cell proliferation, scratch wound healing, transwell migration and matrigel invasion and xenograft tumor growth assays were used to determine the role of flotillin-1 in LUAD progression. Downregulation of flotillin-1 reversed, whereas upregulation of flotillin-1 enhanced, the malignant phenotype of LUAD cells in vitro. Consistently, cells with flotillin-1 knockdown formed smaller tumors in nude mice than cells transfected with the empty vector. Furthermore, the control group demonstrated significantly more tumorigenic effects compared to the flotillin-1-silenced group in the xenograft model of LUAD. In all, there draws a conclusion that flotillin-1 is a tumorigenic protein that plays an important role in promoting the proliferation and tumorigenicity of LUAD, suggesting that flotillin-1 may represent a novel the therapeutic target to LUAD.
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Affiliation(s)
- Ai Yun Guo
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Xu Jun Liang
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Rui Jie Liu
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Xiao Xiao Li
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Wu Bi
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Liu Ying Zhou
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Can E Tang
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Ang Yan
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Zhu Chu Chen
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
| | - Peng Fei Zhang
- a Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University , Changsha , Hunan , China
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60
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Thinon E, Fernandez JP, Molina H, Hang HC. Selective Enrichment and Direct Analysis of Protein S-Palmitoylation Sites. J Proteome Res 2018; 17:1907-1922. [PMID: 29575903 PMCID: PMC6104640 DOI: 10.1021/acs.jproteome.8b00002] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
S-Fatty-acylation is the covalent attachment of long chain fatty acids, predominately palmitate (C16:0, S-palmitoylation), to cysteine (Cys) residues via a thioester linkage on proteins. This post-translational and reversible lipid modification regulates protein function and localization in eukaryotes and is important in mammalian physiology and human diseases. While chemical labeling methods have improved the detection and enrichment of S-fatty-acylated proteins, mapping sites of modification and characterizing the endogenously attached fatty acids are still challenging. Here, we describe the integration and optimization of fatty acid chemical reporter labeling with hydroxylamine-mediated enrichment of S-fatty-acylated proteins and direct tagging of modified Cys residues to selectively map lipid modification sites. This afforded improved enrichment and direct identification of many protein S-fatty-acylation sites compared to previously described methods. Notably, we directly identified the S-fatty-acylation sites of IFITM3, an important interferon-stimulated inhibitor of virus entry, and we further demonstrated that the highly conserved Cys residues are primarily modified by palmitic acid. The methods described here should facilitate the direct analysis of protein S-fatty-acylation sites and their endogenously attached fatty acids in diverse cell types and activation states important for mammalian physiology and diseases.
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Affiliation(s)
- Emmanuelle Thinon
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, New York, NY 10065, USA
- Molecular Cell Biology of Autophagy, The Francis Crick Institute, 1 Midland Road, Kings Cross, London NW1 1AT, UK
| | - Joseph P. Fernandez
- Proteomics Resource Center, The Rockefeller University, New York, New York, USA
| | - Henrik Molina
- Proteomics Resource Center, The Rockefeller University, New York, New York, USA
| | - Howard C. Hang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, New York, NY 10065, USA
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Jensen KL, Sørensen G, Dencker D, Owens WA, Rahbek-Clemmensen T, Brett Lever M, Runegaard AH, Riis Christensen N, Weikop P, Wörtwein G, Fink-Jensen A, Madsen KL, Daws L, Gether U, Rickhag M. PICK1-Deficient Mice Exhibit Impaired Response to Cocaine and Dysregulated Dopamine Homeostasis. eNeuro 2018; 5:ENEURO.0422-17.2018. [PMID: 29911172 PMCID: PMC6001137 DOI: 10.1523/eneuro.0422-17.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 04/18/2018] [Accepted: 04/27/2018] [Indexed: 01/11/2023] Open
Abstract
Protein interacting with C-kinase 1 (PICK1) is a widely expressed scaffold protein known to interact via its PSD-95/discs-large/ZO-1 (PDZ)-domain with several membrane proteins including the dopamine (DA) transporter (DAT), the primary target for cocaine's reinforcing actions. Here, we establish the importance of PICK1 for behavioral effects observed after both acute and repeated administration of cocaine. In PICK1 knock-out (KO) mice, the acute locomotor response to a single injection of cocaine was markedly attenuated. Moreover, in support of a role for PICK1 in neuroadaptive changes induced by cocaine, we observed diminished cocaine intake in a self-administration paradigm. Reduced behavioral effects of cocaine were not associated with decreased striatal DAT distribution and most likely not caused by the ∼30% reduction in synaptosomal DA uptake observed in PICK1 KO mice. The PICK1 KO mice demonstrated preserved behavioral responses to DA receptor agonists supporting intact downstream DA receptor signaling. Unexpectedly, we found a prominent increase in striatal DA content and levels of striatal tyrosine hydroxylase (TH) in PICK1 KO mice. Chronoamperometric recordings showed enhanced DA release in PICK1 KO mice, consistent with increased striatal DA pools. Viral-mediated knock-down (KD) of PICK1 in cultured dopaminergic neurons increased TH expression, supporting a direct cellular effect of PICK1. In summary, in addition to demonstrating a key role of PICK1 in mediating behavioral effects of cocaine, our data reveal a so far unappreciated role of PICK1 in DA homeostasis that possibly involves negative regulation of striatal TH levels.
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Affiliation(s)
- Kathrine Louise Jensen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Gunnar Sørensen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
- Laboratory of Neuropsychiatry, Psychiatric Center Copenhagen, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Ditte Dencker
- Laboratory of Neuropsychiatry, Psychiatric Center Copenhagen, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - William Anthony Owens
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, TX 78229
| | - Troels Rahbek-Clemmensen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Michael Brett Lever
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Annika H. Runegaard
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Nikolaj Riis Christensen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Pia Weikop
- Laboratory of Neuropsychiatry, Psychiatric Center Copenhagen, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Gitta Wörtwein
- Laboratory of Neuropsychiatry, Psychiatric Center Copenhagen, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Anders Fink-Jensen
- Laboratory of Neuropsychiatry, Psychiatric Center Copenhagen, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Kenneth L. Madsen
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Lynette Daws
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, TX 78229
| | - Ulrik Gether
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Mattias Rickhag
- Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen DK-2200, Denmark
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Mackie P, Lebowitz J, Saadatpour L, Nickoloff E, Gaskill P, Khoshbouei H. The dopamine transporter: An unrecognized nexus for dysfunctional peripheral immunity and signaling in Parkinson's Disease. Brain Behav Immun 2018; 70:21-35. [PMID: 29551693 PMCID: PMC5953824 DOI: 10.1016/j.bbi.2018.03.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 03/13/2018] [Accepted: 03/14/2018] [Indexed: 02/06/2023] Open
Abstract
The second-most common neurodegenerative disease, Parkinson's Disease (PD) has three hallmarks: dysfunctional dopamine transmission due, at least in part, to dopamine neuron degeneration; intracellular inclusions of α-synuclein aggregates; and neuroinflammation. The origin and interplay of these features remains a puzzle, as does the underlying mechanism of PD pathogenesis and progression. When viewed in the context of neuroimmunology, dopamine also plays a role in regulating peripheral immune cells. Intriguingly, plasma dopamine levels are altered in PD, suggesting collateral dysregulation of peripheral dopamine transmission. The dopamine transporter (DAT), the main regulator of dopaminergic tone in the CNS, is known to exist in lymphocytes and monocytes/macrophages, but little is known about peripheral DAT biology or how DAT regulates the dopaminergic tone, much less how peripheral DAT alters immune function. Our review is guided by the hypothesis that dysfunctional peripheral dopamine signaling might be linked to the dysfunctional immune responses in PD and thereby suggests a potential bidirectional communication between central and peripheral dopamine systems. This review seeks to foster new perspectives concerning PD pathogenesis and progression.
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Affiliation(s)
- Phillip Mackie
- University of Florida College of Medicine, Department of Neuroscience, Gainesville, FL 32611, United States
| | - Joe Lebowitz
- University of Florida College of Medicine, Department of Neuroscience, Gainesville, FL 32611, United States
| | - Leila Saadatpour
- University of Florida College of Medicine, Department of Neuroscience, Gainesville, FL 32611, United States
| | - Emily Nickoloff
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
| | - Peter Gaskill
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
| | - Habibeh Khoshbouei
- University of Florida College of Medicine, Department of Neuroscience, Gainesville, FL 32611, United States.
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63
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Lorents A, Säälik P, Langel Ü, Pooga M. Arginine-Rich Cell-Penetrating Peptides Require Nucleolin and Cholesterol-Poor Subdomains for Translocation across Membranes. Bioconjug Chem 2018; 29:1168-1177. [PMID: 29510042 DOI: 10.1021/acs.bioconjchem.7b00805] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Proficient transport vectors called cell-penetrating peptides (CPPs) internalize into eukaryotic cells mostly via endocytic pathways and facilitate the uptake of various cargo molecules attached to them. However, some CPPs are able to induce disturbances in the plasma membrane and translocate through it seemingly in an energy-independent manner. For understanding this phenomenon, giant plasma membrane vesicles (GPMVs) derived from the cells are a beneficial model system, since GPMVs have a complex membrane composition comparable to the cells yet lack cellular energy-dependent mechanisms. We investigated the translocation of arginine-rich CPPs into GPMVs with different membrane compositions. Our results demonstrate that lower cholesterol content favors accumulation of nona-arginine and, additionally, sequestration of cholesterol increases the uptake of the CPPs in vesicles with higher cholesterol packing density. Furthermore, the proteins on the surface of vesicles are essential for the uptake of arginine-rich CPPs: downregulation of nucleolin decreases the accumulation and digestion of proteins on the membrane suppresses translocation even more efficiently.
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Affiliation(s)
- Annely Lorents
- Institute of Molecular and Cell Biology , University of Tartu , Riia 23 , 51010 Tartu , Estonia
- Institute of Technology , University of Tartu , Nooruse 1 , 50411 Tartu , Estonia
| | - Pille Säälik
- Institute of Molecular and Cell Biology , University of Tartu , Riia 23 , 51010 Tartu , Estonia
- Institute of Biomedicine and Translational Medicine , University of Tartu , Ravila 14B , 50411 Tartu , Estonia
| | - Ülo Langel
- Institute of Technology , University of Tartu , Nooruse 1 , 50411 Tartu , Estonia
- Department of Neurochemistry , Stockholm University , Svante Arrhenius väg 16B , 10691 Stockholm , Sweden
| | - Margus Pooga
- Institute of Molecular and Cell Biology , University of Tartu , Riia 23 , 51010 Tartu , Estonia
- Institute of Technology , University of Tartu , Nooruse 1 , 50411 Tartu , Estonia
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64
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Sorkina T, Ma S, Larsen MB, Watkins SC, Sorkin A. Small molecule induced oligomerization, clustering and clathrin-independent endocytosis of the dopamine transporter. eLife 2018; 7:32293. [PMID: 29630493 PMCID: PMC5896956 DOI: 10.7554/elife.32293] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 03/22/2018] [Indexed: 12/14/2022] Open
Abstract
Clathrin-independent endocytosis (CIE) mediates internalization of many transmembrane proteins but the mechanisms of cargo recruitment during CIE are poorly understood. We found that the cell-permeable furopyrimidine AIM-100 promotes dramatic oligomerization, clustering and CIE of human and mouse dopamine transporters (DAT), but not of their close homologues, norepinephrine and serotonin transporters. All effects of AIM-100 on DAT and the occupancy of substrate binding sites in the transporter were mutually exclusive, suggesting that AIM-100 may act by binding to DAT. Surprisingly, AIM-100-induced DAT endocytosis was independent of dynamin, cholesterol-rich microdomains and actin cytoskeleton, implying that a novel endocytic mechanism is involved. AIM-100 stimulated trafficking of internalized DAT was also unusual: DAT accumulated in early endosomes without significant recycling or degradation. We propose that AIM-100 augments DAT oligomerization through an allosteric mechanism associated with the DAT conformational state, and that oligomerization-triggered clustering leads to a coat-independent endocytosis and subsequent endosomal retention of DAT.
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Affiliation(s)
- Tatiana Sorkina
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Shiqi Ma
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Mads Breum Larsen
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Simon C Watkins
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Alexander Sorkin
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
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65
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Won JH, Kim SK, Shin IC, Ha HC, Jang JM, Back MJ, Kim DK. Dopamine transporter trafficking is regulated by neutral sphingomyelinase 2/ceramide kinase. Cell Signal 2018; 44:171-187. [DOI: 10.1016/j.cellsig.2018.01.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 12/18/2017] [Accepted: 01/07/2018] [Indexed: 12/13/2022]
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Abstract
Background Much of the structure-based mechanistic understandings of the function of SLC6A neurotransmitter transporters emerged from the study of their bacterial LeuT-fold homologs. It has become evident, however, that structural differences such as the long N- and C-termini of the eukaryotic neurotransmitter transporters are involved in an expanded set of functional properties to the eukaryotic transporters. These functional properties are not shared by the bacterial homologs, which lack the structural elements that appeared later in evolution. However, mechanistic insights into some of the measured functional properties of the eukaryotic transporters that have been suggested to involve these structural elements are sparse or merely descriptive. Results To learn how the structural elements added in evolution enable mechanisms of the eukaryotic transporters in ways not shared with their bacterial LeuT-like homologs, we focused on the human dopamine transporter (hDAT) as a prototype. We present the results of a study employing large-scale molecular dynamics simulations and comparative Markov state model analysis of experimentally determined properties of the wild-type and mutant hDAT constructs. These offer a quantitative outline of mechanisms in which a rich spectrum of interactions of the hDAT N-terminus and C-terminus contribute to the regulation of transporter function (e.g., by phosphorylation) and/or to entirely new phenotypes (e.g., reverse uptake (efflux)) that were added in evolution. Conclusions The findings are consistent with the proposal that the size of eukaryotic neurotransmitter transporter termini increased during evolution to enable more functions (e.g., efflux) not shared with the bacterial homologs. The mechanistic explanations for the experimental findings about the modulation of function in DAT, the serotonin transporter, and other eukaryotic transporters reveal separate roles for the distal and proximal segments of the much larger N-terminus in eukaryotic transporters compared to the bacterial ones. The involvement of the proximal and distal segments — such as the role of the proximal segment in sustaining transport in phosphatidylinositol 4,5-bisphosphate-depleted membranes and of the distal segment in modulating efflux — may represent an evolutionary adaptation required for the function of eukaryotic transporters expressed in various cell types of the same organism that differ in the lipid composition and protein complement of their membrane environment. Electronic supplementary material The online version of this article (10.1186/s12915-018-0495-6) contains supplementary material, which is available to authorized users.
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67
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Hasenhuetl PS, Bhat S, Mayer FP, Sitte HH, Freissmuth M, Sandtner W. A kinetic account for amphetamine-induced monoamine release. J Gen Physiol 2018; 150:431-451. [PMID: 29439119 PMCID: PMC5839721 DOI: 10.1085/jgp.201711915] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 01/18/2018] [Indexed: 01/14/2023] Open
Abstract
This study on serotonin transporters shows that amphetamine-induced monoamine release requires cooperative substrate and cosubstrate binding. A kinetic model is presented that can account qualitatively and quantitatively for the releasing action of amphetamines. The plasmalemmal monoamine transporters for dopamine, norepinephrine, and serotonin (SERT) are targets for amphetamines. In vivo, amphetamines elicit most, if not all, of their actions by triggering monoamine efflux. This is thought to be accomplished by an amphetamine-induced switch from the forward-transport to the substrate-exchange mode. The mechanism underlying this switch has remained elusive; available kinetic models posit that substrates and cosubstrate Na+ ions bind either in a random or in a sequential order. Neither can account for all reported experimental observations. We used electrophysiological recordings to interrogate crucial conformational transitions associated with the binding of five different substrates (serotonin, para-chloroamphetamine, and the high-affinity naphthyl-propan-amines PAL-287, PAL-1045, and PAL-1046) to human SERT expressed in HEK293 cells; specifically, we determined the relaxation kinetics of SERT from a substrate-loaded to a substrate-free state at various intracellular and extracellular Na+ concentrations. These rates and their dependence on intracellular and extracellular Na+ concentrations differed considerably between substrates. We also examined the effect of K+ on substrate affinity and found that K+ enhanced substrate dissociation. A kinetic model was developed, which allowed for random, but cooperative, binding of substrate and Na+ (or K+). The synthetic data generated by this model recapitulated the experimental observations. More importantly, the cooperative binding model accounted for the releasing action of amphetamines without any digression from alternating access. To the best of our knowledge, this model is the first to provide a mechanistic framework for amphetamine-induced monoamine release and to account for the findings that some substrates are less efficacious than others in promoting the substrate-exchange mode.
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Affiliation(s)
- Peter S Hasenhuetl
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Shreyas Bhat
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Felix P Mayer
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Harald H Sitte
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Walter Sandtner
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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68
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Morissette M, Morin N, Rouillard C, Di Paolo T. Membrane cholesterol removal and replenishment affect rat and monkey brain monoamine transporters. Neuropharmacology 2018; 133:289-306. [PMID: 29407218 DOI: 10.1016/j.neuropharm.2018.01.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 01/10/2018] [Accepted: 01/25/2018] [Indexed: 12/16/2022]
Abstract
The dopamine transporter (DAT) is abundantly expressed in the striatum where it removes extracellular dopamine into the cytosol of presynaptic nerve terminals. It is the target of drugs of abuse and antidepressants. There is a loss of the DAT in Parkinson's disease affecting release of levodopa implicated in levodopa-induced dyskinesias. This study investigated the effect of cholesterol on DAT, serotonin transporter (SERT) and vesicular monoamine transporter 2 (VMAT2) in monkey and rat brains in vitro. DAT protein levels measured by Western blot remained unchanged with in vitro methyl-β-cyclodextrin (MCD) incubations to remove membrane cholesterol or with incubations to increase membrane cholesterol content. By contrast, striatal DAT specific binding labelled with [125I]RTI-121 or with [125I]RTI-55 decreased with increasing concentrations of MCD and increased with cholesterol loading. Moreover, [125I]RTI-121 specific binding of striatal membranes depleted of cholesterol with MCD was restored to initial DAT content with addition of cholesterol showing its rapid and reversible effect. By contrast, striatal VMAT2 and SERT specific binding showed no or limited changes by cholesterol manipulations. Similar results were obtained for monkey caudate nucleus, putamen and nucleus accumbens. Membrane microviscosity was assessed by fluorescence polarization spectroscopy, using the probe 1,6-diphenyl-1,3,5-hexatriene. DAT changes positively correlated with changes of membrane microviscosity in rat and monkey brain regions investigated and with membrane cholesterol contents. Similar findings were observed with desmosterol but to a lower extent than with cholesterol. These results show an important effect of cholesterol on the DAT associated with microviscosity changes that should be considered in drug therapies.
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Affiliation(s)
- Marc Morissette
- Neuroscience Research Unit, Centre Hospitalier Universitaire de Québec, CHUL, Quebec City G1V 4G2, Canada
| | - Nicolas Morin
- Neuroscience Research Unit, Centre Hospitalier Universitaire de Québec, CHUL, Quebec City G1V 4G2, Canada; Faculty of Pharmacy, Université Laval, Quebec City G1K 7P4, Canada
| | - Claude Rouillard
- Neuroscience Research Unit, Centre Hospitalier Universitaire de Québec, CHUL, Quebec City G1V 4G2, Canada; Department of Psychiatry and Neuroscience, Faculty of Medicine, Université Laval, Quebec City G1K 7P4, Canada
| | - Thérèse Di Paolo
- Neuroscience Research Unit, Centre Hospitalier Universitaire de Québec, CHUL, Quebec City G1V 4G2, Canada; Faculty of Pharmacy, Université Laval, Quebec City G1K 7P4, Canada.
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69
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Zeppelin T, Ladefoged LK, Sinning S, Periole X, Schiøtt B. A direct interaction of cholesterol with the dopamine transporter prevents its out-to-inward transition. PLoS Comput Biol 2018; 14:e1005907. [PMID: 29329285 PMCID: PMC5811071 DOI: 10.1371/journal.pcbi.1005907] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 02/13/2018] [Accepted: 11/29/2017] [Indexed: 01/30/2023] Open
Abstract
Monoamine transporters (MATs) carry out neurotransmitter reuptake from the synaptic cleft, a key step in neurotransmission, which is targeted in the treatment of neurological disorders. Cholesterol (CHOL), a major component of the synaptic plasma membrane, has been shown to exhibit a modulatory effect on MATs. Recent crystal structures of the dopamine transporter (DAT) revealed the presence of two conserved CHOL-like molecules, suggesting a functional protein-CHOL direct interaction. Here, we present extensive atomistic molecular dynamics (MD) simulations of DAT in an outward-facing conformation. In the absence of bound CHOL, DAT undergoes structural changes reflecting early events of dopamine transport: transition to an inward-facing conformation. In contrast, in the presence of bound CHOL, these conformational changes are inhibited, seemingly by an immobilization of the intracellular interface of transmembrane helix 1a and 5 by CHOL. We also provide evidence, from coarse grain MD simulations that the CHOL sites observed in the DAT crystal structures are preserved in all human monoamine transporters (dopamine, serotonin and norepinephrine), suggesting that our findings might extend to the entire family.
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Affiliation(s)
- Talia Zeppelin
- Department of Chemistry, Aarhus University, Aarhus C, Denmark
| | - Lucy Kate Ladefoged
- Department of Chemistry, Aarhus University, Aarhus C, Denmark
- Interdisciplinary Nanoscience Center, Aarhus University, Aarhus C, Denmark
| | - Steffen Sinning
- Department of Chemistry, Aarhus University, Aarhus C, Denmark
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus C, Denmark
| | - Xavier Periole
- Department of Chemistry, Aarhus University, Aarhus C, Denmark
| | - Birgit Schiøtt
- Department of Chemistry, Aarhus University, Aarhus C, Denmark
- Interdisciplinary Nanoscience Center, Aarhus University, Aarhus C, Denmark
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70
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Xu R, Song X, Su P, Pang Y, Li Q. Identification and characterization of the lamprey Flotillin-1 gene with a role in cell adhesion. FISH & SHELLFISH IMMUNOLOGY 2017; 71:286-294. [PMID: 28687359 DOI: 10.1016/j.fsi.2017.06.061] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 05/31/2017] [Accepted: 06/30/2017] [Indexed: 06/07/2023]
Abstract
Flotillin-1 is a kind of localize into specific cholesterol rich microdomains in cellular membranes and highly conserved lipid rafts marker protein widely distributed in animals and plants. It provides a platform for the reaction of many proteins in signal transduction, as scaffolding plays an important role in transmembrane signaling and cell adhesion. Here, Flotillin-1 protein from lamprey was identified and characterized (designated as L-Flotillin-1). After a partial cDNA sequence of L-Flotillin-1 was identified in a lamprey supraneural body cDNA library, the full-length cDNA was obtained using 3'- and 5'-rapid amplification of cDNA ends (RACE). L-Flotillin-1 encodes 424 amino acids and contains a prohibitin domain and a flotillin repetitive area. The L-Flotillin-1 protein was primarily distributed in kidney, supraneural body, gill, heart, liver and intestine via real-time PCR and immunohistochemistry assays. Immunofluorescence and western blot results showed that L-Flotillin-1 was considered to be used as a marker protein of lamprey lipid rafts and exosomes. Furthermore, overexpression of pEGFP-N1-L-Flotillin-1 induced the up-regulation of vascular cell adhesion molecule-1 (VCAM-1) and intercellular cell adhesion molecule-1 (ICAM-1) mRNA levels. These results indicated that the L-Flotillin-1 gene encodes Flotillin-1 protein that was used as a conserved marker protein and may play an important role in cell adhesion, providing clues for understanding the universal functions of Flotillin-1 proteins in other species and suggesting that these proteins could serve as pattern recognition molecules in immunotherapy. We revealed that Flotillin-1 protein of lamprey overexpression in human cells plays a prevalent role in cell migration and provide new thought of treatment to diseases.
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Affiliation(s)
- Rong Xu
- College of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China
| | - Xiaoping Song
- College of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China; Affilated Zhongshan Hospital, Dalian University Respiratory Medicine, Dalian 116001, China
| | - Peng Su
- College of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China
| | - Yue Pang
- College of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China.
| | - Qingwei Li
- College of Life Sciences, Liaoning Normal University, Dalian 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian 116081, China.
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71
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Karam CS, Javitch JA. Phosphorylation of the Amino Terminus of the Dopamine Transporter: Regulatory Mechanisms and Implications for Amphetamine Action. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2017; 82:205-234. [PMID: 29413521 DOI: 10.1016/bs.apha.2017.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Amphetamines (AMPHs) are potent psychostimulants that are widely used and abused, with profound medical and societal impact. Their actions at dopaminergic neurons are thought to mediate their therapeutic efficacy as well as their liability for abuse and dependence. AMPHs target the dopamine transporter (DAT), the plasmalemmal membrane protein that mediates the inactivation of released dopamine (DA) through its reuptake. AMPHs act as substrates for DAT and are known to cause mobilization of dopamine (DA) to the cell exterior via DAT-mediated reverse transport (efflux). It has become increasingly evident that the mechanisms that regulate AMPH-induced DA efflux are distinct from those that regulate DA uptake. Central to these mechanisms is the phosphorylation of the DAT amino (N)-terminus, which has been repeatedly demonstrated to facilitate DAT-mediated DA efflux, without impacting other aspects of DAT physiology. This review aims to summarize the current status of knowledge regarding DAT N-terminal phosphorylation and its regulation by protein modulators and the membrane microenvironment. A better understanding of these mechanisms may lead to the identification of novel therapeutic approaches that interfere selectively with the pharmacological effects of AMPHs without altering the physiological function of DAT.
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Affiliation(s)
- Caline S Karam
- College of Physicians & Surgeons, Columbia University, New York, NY, United States; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, United States
| | - Jonathan A Javitch
- College of Physicians & Surgeons, Columbia University, New York, NY, United States; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, United States.
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72
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Foster JD, Vaughan RA. Phosphorylation mechanisms in dopamine transporter regulation. J Chem Neuroanat 2017; 83-84:10-18. [PMID: 27836487 PMCID: PMC6705611 DOI: 10.1016/j.jchemneu.2016.10.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 10/26/2016] [Accepted: 10/29/2016] [Indexed: 12/17/2022]
Abstract
The dopamine transporter (DAT) is a plasma membrane phosphoprotein that actively translocates extracellular dopamine (DA) into presynaptic neurons. The transporter is the primary mechanism for control of DA levels and subsequent neurotransmission, and is the target for abused and therapeutic drugs that exert their effects by suppressing reuptake. The transport capacity of DAT is acutely regulated by signaling systems and drug exposure, providing neurons the ability to fine-tune DA clearance in response to specific conditions. Kinase pathways play major roles in these mechanisms, and this review summarizes the current status of DAT phosphorylation characteristics and the evidence linking transporter phosphorylation to control of reuptake and other functions. Greater understanding of these processes may aid in elucidation of their possible contributions to DA disease states and suggest specific phosphorylation sites as targets for therapeutic manipulation of reuptake.
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Affiliation(s)
- James D Foster
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks ND 58202 United States
| | - Roxanne A Vaughan
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks ND 58202 United States.
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Super-resolution microscopy reveals functional organization of dopamine transporters into cholesterol and neuronal activity-dependent nanodomains. Nat Commun 2017; 8:740. [PMID: 28963530 PMCID: PMC5622129 DOI: 10.1038/s41467-017-00790-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 07/27/2017] [Indexed: 01/13/2023] Open
Abstract
Dopamine regulates reward, cognition, and locomotor functions. By mediating rapid reuptake of extracellular dopamine, the dopamine transporter is critical for spatiotemporal control of dopaminergic neurotransmission. Here, we use super-resolution imaging to show that the dopamine transporter is dynamically sequestrated into cholesterol-dependent nanodomains in the plasma membrane of presynaptic varicosities and neuronal projections of dopaminergic neurons. Stochastic optical reconstruction microscopy reveals irregular dopamine transporter nanodomains (∼70 nm mean diameter) that were highly sensitive to cholesterol depletion. Live photoactivated localization microscopy shows a similar dopamine transporter membrane organization in live heterologous cells. In neurons, dual-color dSTORM shows that tyrosine hydroxylase and vesicular monoamine transporter-2 are distinctively localized adjacent to, but not overlapping with, the dopamine transporter nanodomains. The molecular organization of the dopamine transporter in nanodomains is reversibly reduced by short-term activation of NMDA-type ionotropic glutamate receptors, implicating dopamine transporter nanodomain distribution as a potential mechanism to modulate dopaminergic neurotransmission in response to excitatory input.The dopamine transporter (DAT) has a crucial role in the regulation of neurotransmission. Here, the authors use super-resolution imaging to show that DAT clusters into cholesterol-dependent membrane regions that are reversibly regulated by ionotropic glutamate receptors activation.
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74
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Gaskill PJ, Miller DR, Gamble-George J, Yano H, Khoshbouei H. HIV, Tat and dopamine transmission. Neurobiol Dis 2017; 105:51-73. [PMID: 28457951 PMCID: PMC5541386 DOI: 10.1016/j.nbd.2017.04.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 04/04/2017] [Accepted: 04/16/2017] [Indexed: 01/02/2023] Open
Abstract
Human Immunodeficiency Virus (HIV) is a progressive infection that targets the immune system, affecting more than 37 million people around the world. While combinatorial antiretroviral therapy (cART) has lowered mortality rates and improved quality of life in infected individuals, the prevalence of HIV associated neurocognitive disorders is increasing and HIV associated cognitive decline remains prevalent. Recent research has suggested that HIV accessory proteins may be involved in this decline, and several studies have indicated that the HIV protein transactivator of transcription (Tat) can disrupt normal neuronal and glial function. Specifically, data indicate that Tat may directly impact dopaminergic neurotransmission, by modulating the function of the dopamine transporter and specifically damaging dopamine-rich regions of the CNS. HIV infection of the CNS has long been associated with dopaminergic dysfunction, but the mechanisms remain undefined. The specific effect(s) of Tat on dopaminergic neurotransmission may be, at least partially, a mechanism by which HIV infection directly or indirectly induces dopaminergic dysfunction. Therefore, precisely defining the specific effects of Tat on the dopaminergic system will help to elucidate the mechanisms by which HIV infection of the CNS induces neuropsychiatric, neurocognitive and neurological disorders that involve dopaminergic neurotransmission. Further, this will provide a discussion of the experiments needed to further these investigations, and may help to identify or develop new therapeutic approaches for the prevention or treatment of these disorders in HIV-infected individuals.
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Affiliation(s)
- Peter J Gaskill
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States.
| | - Douglas R Miller
- Department of Neuroscience, University of Florida, Gainesville, FL 32611, United States
| | - Joyonna Gamble-George
- Department of Neuroscience, University of Florida, Gainesville, FL 32611, United States
| | - Hideaki Yano
- National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, United States
| | - Habibeh Khoshbouei
- Department of Neuroscience, University of Florida, Gainesville, FL 32611, United States.
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75
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Karam CS, Sen N, Javitch JA. Phospho-specific antibodies targeting the amino terminus of the human dopamine transporter. J Chem Neuroanat 2017; 83-84:91-98. [PMID: 28571709 DOI: 10.1016/j.jchemneu.2017.05.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 05/11/2017] [Indexed: 11/29/2022]
Abstract
The dopamine transporter (DAT), which mediates the inactivation of released dopamine through its reuptake, is the primary molecular target for the actions of psychostimulants. An increasing number of studies support an essential role for phosphorylation of serines (Ser) in the distal amino (N) terminus of DAT in regulating its function. Still, the molecular details of the regulation of phosphorylation and its impact on function are not fully understood. To address this, we have developed and characterized two distinct phospho-antibodies that recognize human DAT when it is phosphorylated at Ser7 or Ser12. Our data show that treatment of cells with phorbol 12-myristate 13-acetate (PMA), amphetamine (AMPH) or okadaic acid (OA) leads to an increase in the phosphorylation of DAT at both residues and that these responses are dependent on the activity of protein kinase C. We also show that AMPH-induced and OA-induced phosphorylation of DAT are dependent on Ca2+/calmodulin-dependent protein kinase α. Our data further suggest that the lipid raft localization of DAT is necessary for efficient N-terminal phosphorylation and for the associated behavioral effects of AMPH, demonstrating the potential of these novel antibodies as powerful tools to study DAT regulation and function in vivo.
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Affiliation(s)
- Caline S Karam
- Department of Psychiatry, College of Physicians & Surgeons, Columbia University, New York, NY 10032, USA; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Namita Sen
- Department of Psychiatry, College of Physicians & Surgeons, Columbia University, New York, NY 10032, USA; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Jonathan A Javitch
- Department of Psychiatry, College of Physicians & Surgeons, Columbia University, New York, NY 10032, USA; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA; Department of Pharmacology, College of Physicians & Surgeons, Columbia University, New York, NY 10032, USA.
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76
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Rastedt DE, Vaughan RA, Foster JD. Palmitoylation mechanisms in dopamine transporter regulation. J Chem Neuroanat 2017; 83-84:3-9. [PMID: 28115272 DOI: 10.1016/j.jchemneu.2017.01.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 12/21/2016] [Accepted: 01/17/2017] [Indexed: 02/01/2023]
Abstract
The neurotransmitter dopamine (DA) plays a key role in several biological processes including reward, mood, motor activity and attention. Synaptic DA homeostasis is controlled by the dopamine transporter (DAT) which transports extracellular DA into the presynaptic neuron after release and regulates its availability to receptors. Many neurological disorders such as schizophrenia, bipolar disorder, Parkinson disease and attention-deficit hyperactivity disorder are associated with imbalances in DA homeostasis that may be related to DAT dysfunction. DAT is also a target of psychostimulant and therapeutic drugs that inhibit DA reuptake and lead to elevated dopaminergic neurotransmission. We have recently demonstrated the acute and chronic modulation of DA reuptake activity and DAT stability through S-palmitoylation, the linkage of a 16-carbon palmitate group to cysteine via a thioester bond. This review summarizes the properties and regulation of DAT palmitoylation and describes how it serves to affect various transporter functions. Better understanding of the role of palmitoylation in regulation of DAT function may lead to identification of therapeutic targets for modulation of DA homeostasis in the treatment of dopaminergic disorders.
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Affiliation(s)
- Danielle E Rastedt
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, United States
| | - Roxanne A Vaughan
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, United States
| | - James D Foster
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND 58202, United States.
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77
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Luo Y, Akama T, Okayama A, Yoshihara A, Sue M, Oda K, Hayashi M, Ishido Y, Hirano H, Hiroi N, Katoh R, Suzuki K. A Novel Role for Flotillin-Containing Lipid Rafts in Negative-Feedback Regulation of Thyroid-Specific Gene Expression by Thyroglobulin. Thyroid 2016; 26:1630-1639. [PMID: 27676653 DOI: 10.1089/thy.2016.0187] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Thyroglobulin (Tg) stored in thyroid follicles regulates follicular function in thyroid hormone (TH) synthesis by suppressing thyroid-specific gene expression in a concentration-dependent manner. Thus, Tg is an intrinsic negative-feedback regulator that can restrain the effect of thyrotropin (TSH) in the follicle. However, the underlying mechanisms by which Tg exerts its prominent autoregulatory effect following recognition by thyrocytes remains unclear. METHODS In order to identify potential proteins that recognize and interact with Tg, mass spectrometry was used to analyze immunoprecipitated Tg-bound proteins derived from Tg-treated rat thyroid FRTL-5 cells. RESULTS Flotillin 1 and flotillin 2, two homologs that are integral membrane proteins in lipid rafts, were identified as novel Tg-binding proteins with high confidence. Further studies revealed that flotillins physically interact with endocytosed Tg, and together these proteins redistribute from the cell membrane to cytoplasmic vesicles. Treatment with the lipid raft disrupter methyl-β-cyclodextrin abolished both the endocytosis and the negative-feedback effect of Tg on thyroid-specific gene expression. Meanwhile, siRNA-mediated knockdown of flotillin 1 or flotillin 2 also significantly inhibited Tg effects on gene expression. CONCLUSION Together these results indicate that flotillin-containing lipid rafts are essential for follicular Tg to be recognized by thyrocytes and exert its negative-feedback effects in the thyroid.
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Affiliation(s)
- Yuqian Luo
- 1 Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University , Tokyo, Japan
- 2 Laboratory of Molecular Diagnostics, Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases , Tokyo, Japan
- 3 Department of Pathology, Faculty of Medicine, University of Yamanashi , Yamanashi, Japan
| | - Takeshi Akama
- 2 Laboratory of Molecular Diagnostics, Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases , Tokyo, Japan
| | - Akiko Okayama
- 4 Advanced Medical Research Center, Yokohama City University , Yokohama, Japan
| | - Aya Yoshihara
- 1 Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University , Tokyo, Japan
- 2 Laboratory of Molecular Diagnostics, Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases , Tokyo, Japan
- 5 Department of Education Planning and Development, Faculty of Medicine, Toho University , Tokyo, Japan
| | - Mariko Sue
- 2 Laboratory of Molecular Diagnostics, Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases , Tokyo, Japan
- 6 Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Toho University , Tokyo, Japan
| | - Kenzaburo Oda
- 1 Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University , Tokyo, Japan
- 2 Laboratory of Molecular Diagnostics, Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases , Tokyo, Japan
- 6 Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Toho University , Tokyo, Japan
| | - Moyuru Hayashi
- 1 Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University , Tokyo, Japan
- 2 Laboratory of Molecular Diagnostics, Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases , Tokyo, Japan
| | - Yuko Ishido
- 1 Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University , Tokyo, Japan
- 2 Laboratory of Molecular Diagnostics, Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases , Tokyo, Japan
| | - Hisashi Hirano
- 3 Department of Pathology, Faculty of Medicine, University of Yamanashi , Yamanashi, Japan
| | - Naoki Hiroi
- 5 Department of Education Planning and Development, Faculty of Medicine, Toho University , Tokyo, Japan
| | - Ryohei Katoh
- 3 Department of Pathology, Faculty of Medicine, University of Yamanashi , Yamanashi, Japan
| | - Koichi Suzuki
- 1 Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University , Tokyo, Japan
- 2 Laboratory of Molecular Diagnostics, Department of Mycobacteriology, Leprosy Research Center, National Institute of Infectious Diseases , Tokyo, Japan
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78
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Bermingham DP, Blakely RD. Kinase-dependent Regulation of Monoamine Neurotransmitter Transporters. Pharmacol Rev 2016; 68:888-953. [PMID: 27591044 PMCID: PMC5050440 DOI: 10.1124/pr.115.012260] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Modulation of neurotransmission by the monoamines dopamine (DA), norepinephrine (NE), and serotonin (5-HT) is critical for normal nervous system function. Precise temporal and spatial control of this signaling in mediated in large part by the actions of monoamine transporters (DAT, NET, and SERT, respectively). These transporters act to recapture their respective neurotransmitters after release, and disruption of clearance and reuptake has significant effects on physiology and behavior and has been linked to a number of neuropsychiatric disorders. To ensure adequate and dynamic control of these transporters, multiple modes of control have evolved to regulate their activity and trafficking. Central to many of these modes of control are the actions of protein kinases, whose actions can be direct or indirectly mediated by kinase-modulated protein interactions. Here, we summarize the current state of our understanding of how protein kinases regulate monoamine transporters through changes in activity, trafficking, phosphorylation state, and interacting partners. We highlight genetic, biochemical, and pharmacological evidence for kinase-linked control of DAT, NET, and SERT and, where applicable, provide evidence for endogenous activators of these pathways. We hope our discussion can lead to a more nuanced and integrated understanding of how neurotransmitter transporters are controlled and may contribute to disorders that feature perturbed monoamine signaling, with an ultimate goal of developing better therapeutic strategies.
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Affiliation(s)
- Daniel P Bermingham
- Department of Pharmacology (D.P.B., R.D.B.) and Psychiatry (R.D.B.), Vanderbilt University Medical Center, Nashville, Tennessee; and Department of Biomedical Sciences, Charles E. Schmidt College of Medicine and Brain Institute, Florida Atlantic University, Jupiter, Florida (R.D.B.)
| | - Randy D Blakely
- Department of Pharmacology (D.P.B., R.D.B.) and Psychiatry (R.D.B.), Vanderbilt University Medical Center, Nashville, Tennessee; and Department of Biomedical Sciences, Charles E. Schmidt College of Medicine and Brain Institute, Florida Atlantic University, Jupiter, Florida (R.D.B.)
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79
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Role of flotillins in the endocytosis of GPCR in salivary gland epithelial cells. Biochem Biophys Res Commun 2016; 476:237-244. [DOI: 10.1016/j.bbrc.2016.05.103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 05/20/2016] [Indexed: 11/21/2022]
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80
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Völlner F, Ali J, Kurrle N, Exner Y, Eming R, Hertl M, Banning A, Tikkanen R. Loss of flotillin expression results in weakened desmosomal adhesion and Pemphigus vulgaris-like localisation of desmoglein-3 in human keratinocytes. Sci Rep 2016; 6:28820. [PMID: 27346727 PMCID: PMC4922016 DOI: 10.1038/srep28820] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 06/09/2016] [Indexed: 01/01/2023] Open
Abstract
Desmosomes are adhesion plaques that mediate cell-cell adhesion in many tissues, including the epidermis, and generate mechanical resistance to tissues. The extracellular domains of desmosomal cadherin proteins, desmogleins and desmocollins, are required for the interaction with cadherins of the neighbouring cells, whereas their cytoplasmic tails associate with cytoplasmic proteins which mediate connection to intermediate filaments. Disruption of desmosomal adhesion by mutations, autoantibodies or bacterial toxins results in severe human disorders of e.g. the skin and the heart. Despite the vital role of desmosomes in various tissues, the details of their molecular assembly are not clear. We here show that the two members of the flotillin protein family directly interact with the cytoplasmic tails of desmogleins. Depletion of flotillins in human keratinocytes results in weakened desmosomal adhesion and reduced expression of desmoglein-3, most likely due to a reduction in the desmosomal pool due to increased turnover. In the absence of flotillins, desmoglein-3 shows an altered localisation pattern in the cell-cell junctions of keratinocytes, which is highly similar to the localisation observed upon treatment with pemphigus vulgaris autoantibodies. Thus, our data show that flotillins, which have previously been connected to the classical cadherins, are also of importance for the desmosomal cell adhesion.
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Affiliation(s)
- Frauke Völlner
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Jawahir Ali
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Nina Kurrle
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Yvonne Exner
- Department of Dermatology and Allergology, Philipps University of Marburg, Baldingerstrasse, 35043 Marburg, Germany
| | - Rüdiger Eming
- Department of Dermatology and Allergology, Philipps University of Marburg, Baldingerstrasse, 35043 Marburg, Germany
| | - Michael Hertl
- Department of Dermatology and Allergology, Philipps University of Marburg, Baldingerstrasse, 35043 Marburg, Germany
| | - Antje Banning
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
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81
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Reddy IA, Pino JA, Weikop P, Osses N, Sørensen G, Bering T, Valle C, Bluett RJ, Erreger K, Wortwein G, Reyes JG, Graham D, Stanwood GD, Hackett TA, Patel S, Fink-Jensen A, Torres GE, Galli A. Glucagon-like peptide 1 receptor activation regulates cocaine actions and dopamine homeostasis in the lateral septum by decreasing arachidonic acid levels. Transl Psychiatry 2016; 6:e809. [PMID: 27187231 PMCID: PMC5070047 DOI: 10.1038/tp.2016.86] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 02/19/2016] [Accepted: 03/30/2016] [Indexed: 12/12/2022] Open
Abstract
Agonism of the glucagon-like peptide 1 (GLP-1) receptor (GLP-1R) has been effective at treating aspects of addictive behavior for a number of abused substances, including cocaine. However, the molecular mechanisms and brain circuits underlying the therapeutic effects of GLP-1R signaling on cocaine actions remain elusive. Recent evidence has revealed that endogenous signaling at the GLP-1R within the forebrain lateral septum (LS) acts to reduce cocaine-induced locomotion and cocaine conditioned place preference, both considered dopamine (DA)-associated behaviors. DA terminals project from the ventral tegmental area to the LS and express the DA transporter (DAT). Cocaine acts by altering DA bioavailability by targeting the DAT. Therefore, GLP-1R signaling might exert effects on DAT to account for its regulation of cocaine-induced behaviors. We show that the GLP-1R is highly expressed within the LS. GLP-1, in LS slices, significantly enhances DAT surface expression and DAT function. Exenatide (Ex-4), a long-lasting synthetic analog of GLP-1 abolished cocaine-induced elevation of DA. Interestingly, acute administration of Ex-4 reduces septal expression of the retrograde messenger 2-arachidonylglycerol (2-AG), as well as a product of its presynaptic degradation, arachidonic acid (AA). Notably, AA reduces septal DAT function pointing to AA as a novel regulator of central DA homeostasis. We further show that AA oxidation product γ-ketoaldehyde (γ-KA) forms adducts with the DAT and reduces DAT plasma membrane expression and function. These results support a mechanism in which postsynaptic septal GLP-1R activation regulates 2-AG levels to alter presynaptic DA homeostasis and cocaine actions through AA.
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Affiliation(s)
- I A Reddy
- Neuroscience Program, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - J A Pino
- Instituto de Química, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
- Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, FL, USA
| | - P Weikop
- Laboratory of Neuropsychiatry, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Psychiatric Centre Copenhagen, University Hospital Copenhagen, Copenhagen, Denmark
| | - N Osses
- Instituto de Química, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - G Sørensen
- Laboratory of Neuropsychiatry, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Psychiatric Centre Copenhagen, University Hospital Copenhagen, Copenhagen, Denmark
| | - T Bering
- Laboratory of Neuropsychiatry, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - C Valle
- Departamento de Ciencias Básicas, Universidad de Viña del Mar, Viña del Mar, Chile
| | - R J Bluett
- Neuroscience Program, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Psychiatry, Vanderbilt University Medical Center, Nashville, TN, USA
| | - K Erreger
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - G Wortwein
- Laboratory of Neuropsychiatry, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - J G Reyes
- Instituto de Química, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - D Graham
- Department of Biomedical Sciences and Center for Brain Repair, Florida State University, Tallahassee, FL, USA
| | - G D Stanwood
- Department of Biomedical Sciences and Center for Brain Repair, Florida State University, Tallahassee, FL, USA
| | - T A Hackett
- Neuroscience Program, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - S Patel
- Department of Psychiatry, Vanderbilt University Medical Center, Nashville, TN, USA
| | - A Fink-Jensen
- Laboratory of Neuropsychiatry, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Psychiatric Centre Copenhagen, University Hospital Copenhagen, Copenhagen, Denmark
| | - G E Torres
- Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, FL, USA
| | - A Galli
- Neuroscience Program, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA
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82
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Increased expression of endocytosis-Related proteins in rat hippocampus following 10-day electroconvulsive seizure treatment. Neurosci Lett 2016; 624:85-91. [PMID: 27177725 DOI: 10.1016/j.neulet.2016.05.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 05/06/2016] [Accepted: 05/09/2016] [Indexed: 12/16/2022]
Abstract
Although electroconvulsive therapy (ECT) is clinically used for severe depression and drug-resistant Parkinson's disease, its exact biological background and mechanism have not yet been fully elucidated. Two potential explanations have been presented so far to explain the increased neuroplastic and resilient profiles of multiple ECT administrations. One is the alteration of central neurotransmitter receptor densities and the other is the expressional upregulation of brain derived neurotrophic factor in various brain regions with enhanced hippocampal neurogenesis and mossy fiber sprouting. In the present report, western blot analyses revealed significantly upregulated expression of various endocytosis-related proteins following 10-day electroconvulsive seizure (ECS) treatment in rat hippocampal homogenates and hippocampal lipid raft fractions extracted using an ultracentrifugation procedure. Upregulated proteins included endocytosis-related scaffolding proteins (caveolin-1, flotillin-1, and heavy and light chains of clathrin) and small GTPases (Rab5, Rab7, Rab11, and Rab4) specifically expressed on various types of endosomes. Two scaffolding proteins, caveolin-1 and flotillin-1, were also increased in the lipid raft fraction. Together with our previous finding of increased autophagy-related proteins in the hippocampal region, the present results suggest membrane trafficking machinery is enhanced following 10-day ECS treatment. We consider that the membrane trafficking machinery that transports functional proteins in the neuronal cells and from or into the synaptic membranes is one of the new candidates supporting the cellular and behavioral neuroplastic profiles of ECS treatments in animal experiments and ECT administrations in clinical settings.
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83
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German CL, Baladi MG, McFadden LM, Hanson GR, Fleckenstein AE. Regulation of the Dopamine and Vesicular Monoamine Transporters: Pharmacological Targets and Implications for Disease. Pharmacol Rev 2016; 67:1005-24. [PMID: 26408528 DOI: 10.1124/pr.114.010397] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Dopamine (DA) plays a well recognized role in a variety of physiologic functions such as movement, cognition, mood, and reward. Consequently, many human disorders are due, in part, to dysfunctional dopaminergic systems, including Parkinson's disease, attention deficit hyperactivity disorder, and substance abuse. Drugs that modify the DA system are clinically effective in treating symptoms of these diseases or are involved in their manifestation, implicating DA in their etiology. DA signaling and distribution are primarily modulated by the DA transporter (DAT) and by vesicular monoamine transporter (VMAT)-2, which transport DA into presynaptic terminals and synaptic vesicles, respectively. These transporters are regulated by complex processes such as phosphorylation, protein-protein interactions, and changes in intracellular localization. This review provides an overview of 1) the current understanding of DAT and VMAT2 neurobiology, including discussion of studies ranging from those conducted in vitro to those involving human subjects; 2) the role of these transporters in disease and how these transporters are affected by disease; and 3) and how selected drugs alter the function and expression of these transporters. Understanding the regulatory processes and the pathologic consequences of DAT and VMAT2 dysfunction underlies the evolution of therapeutic development for the treatment of DA-related disorders.
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Affiliation(s)
- Christopher L German
- School of Dentistry (C.L.G., M.G.B., G.R.H., A.E.F.) and Department of Pharmacology and Toxicology (L.M.M., G.R.H.), University of Utah, Salt Lake City, Utah
| | - Michelle G Baladi
- School of Dentistry (C.L.G., M.G.B., G.R.H., A.E.F.) and Department of Pharmacology and Toxicology (L.M.M., G.R.H.), University of Utah, Salt Lake City, Utah
| | - Lisa M McFadden
- School of Dentistry (C.L.G., M.G.B., G.R.H., A.E.F.) and Department of Pharmacology and Toxicology (L.M.M., G.R.H.), University of Utah, Salt Lake City, Utah
| | - Glen R Hanson
- School of Dentistry (C.L.G., M.G.B., G.R.H., A.E.F.) and Department of Pharmacology and Toxicology (L.M.M., G.R.H.), University of Utah, Salt Lake City, Utah
| | - Annette E Fleckenstein
- School of Dentistry (C.L.G., M.G.B., G.R.H., A.E.F.) and Department of Pharmacology and Toxicology (L.M.M., G.R.H.), University of Utah, Salt Lake City, Utah
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84
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Ibáñez I, Díez-Guerra FJ, Giménez C, Zafra F. Activity dependent internalization of the glutamate transporter GLT-1 mediated by β-arrestin 1 and ubiquitination. Neuropharmacology 2016; 107:376-386. [PMID: 27044663 DOI: 10.1016/j.neuropharm.2016.03.042] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 03/07/2016] [Accepted: 03/24/2016] [Indexed: 10/22/2022]
Abstract
GLT-1 is the main glutamate transporter in the brain and undergoes trafficking processes that control its concentration on the cell surface thereby shaping glutamatergic neurotransmission. We have investigated how the traffic of GLT-1 is regulated by transporter activity. We report that internalization of GLT-1 from the cell surface is accelerated by transportable substrates like glutamate or aspartate, as well as by the transportable inhibitor L-trans-2,4-PDC, but not by the non-substrate inhibitor WAY 213613 in primary mixed cultures and in transiently transfected HEK293 cells. Analysis of the mechanism of endocytosis in HEK293 cells revealed that glutamate promoted the association with the transporter of the adaptor protein β-arrestin and the ubiquitin ligase Nedd4-2. The addition of glutamate is accompanied by an increase in the transporter ubiquitination, and the internalization is suppressed by an ubiquitination inhibitor (PYR41), and in a mutant defective in C-terminal lysines. The glutamate triggered endocytosis was also suppressed by siRNA for β-arrestin. This regulatory mechanism might be relevant in controlling the amount of transporter on the cell surface in conditions such as ischemia or traumatic brain injury, where extracellular concentrations of glutamate are persistently elevated.
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Affiliation(s)
- Ignacio Ibáñez
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras, Spain; IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - F Javier Díez-Guerra
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
| | - Cecilio Giménez
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras, Spain; IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain
| | - Francisco Zafra
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras, Spain; IdiPAZ, Instituto de Salud Carlos III, Madrid, Spain.
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85
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LeVine MV, Cuendet MA, Khelashvili G, Weinstein H. Allosteric Mechanisms of Molecular Machines at the Membrane: Transport by Sodium-Coupled Symporters. Chem Rev 2016; 116:6552-87. [PMID: 26892914 DOI: 10.1021/acs.chemrev.5b00627] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Solute transport across cell membranes is ubiquitous in biology as an essential physiological process. Secondary active transporters couple the unfavorable process of solute transport against its concentration gradient to the energetically favorable transport of one or several ions. The study of such transporters over several decades indicates that their function involves complex allosteric mechanisms that are progressively being revealed in atomistic detail. We focus on two well-characterized sodium-coupled symporters: the bacterial amino acid transporter LeuT, which is the prototype for the "gated pore" mechanism in the mammalian synaptic monoamine transporters, and the archaeal GltPh, which is the prototype for the "elevator" mechanism in the mammalian excitatory amino acid transporters. We present the evidence for the role of allostery in the context of a quantitative formalism that can reconcile biochemical and biophysical data and thereby connects directly to recent insights into the molecular structure and dynamics of these proteins. We demonstrate that, while the structures and mechanisms of these transporters are very different, the available data suggest a common role of specific models of allostery in their functions. We argue that such allosteric mechanisms appear essential not only for sodium-coupled symport in general but also for the function of other types of molecular machines in the membrane.
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Affiliation(s)
- Michael V LeVine
- Department of Physiology and Biophysics, ‡HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Cornell Medical College of Cornell University , New York, New York 10065, United States
| | - Michel A Cuendet
- Department of Physiology and Biophysics, ‡HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Cornell Medical College of Cornell University , New York, New York 10065, United States
| | - George Khelashvili
- Department of Physiology and Biophysics, ‡HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Cornell Medical College of Cornell University , New York, New York 10065, United States
| | - Harel Weinstein
- Department of Physiology and Biophysics, ‡HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Cornell Medical College of Cornell University , New York, New York 10065, United States
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86
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Eenjes E, Dragich JM, Kampinga HH, Yamamoto A. Distinguishing aggregate formation and aggregate clearance using cell-based assays. J Cell Sci 2016; 129:1260-70. [PMID: 26818841 DOI: 10.1242/jcs.179978] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 01/21/2016] [Indexed: 01/01/2023] Open
Abstract
The accumulation of ubiquitylated proteinaceous inclusions represents a complex process, reflecting the disequilibrium between aggregate formation and aggregate clearance. Although decreasing aggregate formation or augmenting aggregate clearance will ultimately lead to a diminished aggregate burden, in terms of disease pathogenesis, the different approaches can have distinct outcomes. Using a novel cell-based assay that can distinguish newly formed versus preformed inclusions, we demonstrate that two proteins previously implicated in the autophagic clearance of expanded polyglutamine inclusions, HspB7 and Alfy (also known as WDFY3), actually affect very distinct cellular processes to affect aggregate burden. Using this cell-based assay, we also establish that constitutive expression of the aggregation-prone protein can measurably slow the elimination of protein aggregates, given that not all aggregates appear to be available for degradation. This new assay can therefore not only determine at what step a modifier might influence aggregate burden, but also can be used to provide new insights into how protein aggregates are targeted for degradation.
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Affiliation(s)
- Evelien Eenjes
- Columbia University, Department of Neurology, New York, NY 10032, USA University Medical Center Groningen, University of Groningen, Department of Cell Biology, Groningen 9713, The Netherlands
| | - Joanna M Dragich
- Columbia University, Department of Neurology, New York, NY 10032, USA
| | - Harm H Kampinga
- University Medical Center Groningen, University of Groningen, Department of Cell Biology, Groningen 9713, The Netherlands
| | - Ai Yamamoto
- Columbia University, Department of Neurology, New York, NY 10032, USA Columbia University, Department of Pathology and Cell Biology, New York, NY 10032, USA
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87
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Membrane potential shapes regulation of dopamine transporter trafficking at the plasma membrane. Nat Commun 2016; 7:10423. [PMID: 26804245 PMCID: PMC4737753 DOI: 10.1038/ncomms10423] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 12/09/2015] [Indexed: 12/17/2022] Open
Abstract
The dopaminergic system is essential for cognitive processes, including reward, attention and motor control. In addition to DA release and availability of synaptic DA receptors, timing and magnitude of DA neurotransmission depend on extracellular DA-level regulation by the dopamine transporter (DAT), the membrane expression and trafficking of which are highly dynamic. Data presented here from real-time TIRF (TIRFM) and confocal microscopy coupled with surface biotinylation and electrophysiology suggest that changes in the membrane potential alone, a universal yet dynamic cellular property, rapidly alter trafficking of DAT to and from the surface membrane. Broadly, these findings suggest that cell-surface DAT levels are sensitive to membrane potential changes, which can rapidly drive DAT internalization from and insertion into the cell membrane, thus having an impact on the capacity for DAT to regulate extracellular DA levels. The dopaminergic system has important roles in a number of cognitive process. Here, the authors use detailed analysis of dopamine transporter trafficking to show its levels at the cell surface are sensitive to changes in membrane potential.
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88
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Abstract
UNLABELLED The dopamine (DA) transporter (DAT) controls dopaminergic neurotransmission by removing extracellular DA. Although DA reuptake is proposed to be regulated by DAT traffic to and from the cell surface, the membrane trafficking system involved in the endocytic cycling of DAT in the intact mammalian brain has not been characterized. Hence, we performed immunolabeling and quantitative analysis of the subcellular and regional distribution of DAT using the transgenic knock-in mouse expressing hemagglutinin (HA) epitope-tagged DAT (HA-DAT) and by using a combination of electron microscopy and a novel method for immunofluorescence labeling of HA-DAT in acute sagittal brain slices. Both approaches demonstrated that, in midbrain somatodendritic regions, HA-DAT was present in the plasma membrane, endoplasmic reticulum, and Golgi complex, with a small fraction in early and recycling endosomes and an even smaller fraction in late endosomes and lysosomes. In the striatum and in axonal tracts between the midbrain and striatum, HA-DAT was detected predominantly in the plasma membrane, and quantitative analysis revealed increased DAT density in striatal compared with midbrain plasma membranes. Endosomes were strikingly rare and lysosomes were absent in striatal axons, in which there was little intracellular HA-DAT. Acute administration of amphetamine in vivo (60 min) or to slices ex vivo (10-60 min) did not result in detectable changes in DAT distribution. Altogether, these data provide evidence for regional differences in DAT plasma membrane targeting and retention and suggest a surprisingly low level of endocytic trafficking of DAT in the striatum along with limited DAT endocytic activity in somatodendritic areas. SIGNIFICANCE STATEMENT The dopamine transporter (DAT) is the key regulator of the dopamine neurotransmission in the CNS. In the present study, we developed a new approach for studying DAT localization and dynamics in intact neurons in acute sagittal brain slices from the knock-in mouse expressing epitope-tagged DAT. For the first time, the fluorescence imaging analysis of DAT was combined with the immunogold labeling of DAT and quantitative electron microscopy. In contrast to numerous studies of DAT trafficking in heterologous expression systems and dissociated cultured neurons, studies in intact neurons revealed a surprisingly low amount of endocytic trafficking of DAT at steady state and after acute amphetamine treatment and suggested that non-vesicular transport could be the main mechanism establishing DAT distribution within the dopaminergic neuron.
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89
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Characterization of the NPC1L1 gene and proteome from an exceptional responder to ezetimibe. Atherosclerosis 2015; 246:78-86. [PMID: 26761771 DOI: 10.1016/j.atherosclerosis.2015.12.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 12/17/2015] [Accepted: 12/22/2015] [Indexed: 12/27/2022]
Abstract
BACKGROUND Strategies to reduce LDL-cholesterol involve reductions in cholesterol synthesis or absorption. We identified a familial hypercholesterolemia patient with an exceptional response to the cholesterol absorption inhibitor, ezetimibe. Niemann-Pick C 1-like 1 (NPC1L1) is the molecular target of ezetimibe. METHODS AND RESULTS Sequencing identified nucleotide changes predicted to change amino acids 52 (L52P), 300 (I300T) and 489 (S489G) in exceptional NPC1L1. In silico analyses identified increased stability and cholesterol binding affinity in L52P-NPC1L1 versus WT-NPC1L1. HEK293 cells overexpressing WT-NPC1L1 or NPC1L1 harboring amino acid changes singly or in combination (Comb-NPC1L1) had reduced cholesterol uptake in Comb-NPC1L1 when ezetimibe was present. Cholesterol uptake was reduced by ezetimibe in L52P-NPC1L1, I300T-NPC1L1, but increased in S489G-NPC1L1 overexpressing cells. Immunolocalization studies found preferential plasma membrane localization of mutant NPC1L1 independent of ezetimibe. Flotillin 1 and 2 expression was reduced and binding to Comb-NPC1L1 was reduced independent of ezetimibe exposure. Proteomic analyses identified increased association with proteins that modulate intermediate filament proteins in Comb-NPC1L1 versus WT-NPC1L1 treated with ezetimibe. CONCLUSION This is the first detailed analysis of the role of NPC1L1 mutations in an exceptional responder to ezetimibe. The results point to a complex set of events in which the combined mutations were shown to affect cholesterol uptake in the presence of ezetimibe. Proteomic analysis suggests that the exceptional response may also lie in the nature of interactions with cytosolic proteins.
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90
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Ack1 is a dopamine transporter endocytic brake that rescues a trafficking-dysregulated ADHD coding variant. Proc Natl Acad Sci U S A 2015; 112:15480-5. [PMID: 26621748 DOI: 10.1073/pnas.1512957112] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The dopamine (DA) transporter (DAT) facilitates high-affinity presynaptic DA reuptake that temporally and spatially constrains DA neurotransmission. Aberrant DAT function is implicated in attention-deficit/hyperactivity disorder and autism spectrum disorder. DAT is a major psychostimulant target, and psychostimulant reward strictly requires binding to DAT. DAT function is acutely modulated by dynamic membrane trafficking at the presynaptic terminal and a PKC-sensitive negative endocytic mechanism, or "endocytic brake," controls DAT plasma membrane stability. However, the molecular basis for the DAT endocytic brake is unknown, and it is unknown whether this braking mechanism is unique to DAT or common to monoamine transporters. Here, we report that the cdc42-activated, nonreceptor tyrosine kinase, Ack1, is a DAT endocytic brake that stabilizes DAT at the plasma membrane and is released in response to PKC activation. Pharmacologic and shRNA-mediated Ack1 silencing enhanced basal DAT internalization and blocked PKC-stimulated DAT internalization, but had no effects on SERT endocytosis. Both cdc42 activation and PKC stimulation converge on Ack1 to control Ack1 activity and DAT endocytic capacity, and Ack1 inactivation is required for stimulated DAT internalization downstream of PKC activation. Moreover, constitutive Ack1 activation is sufficient to rescue the gain-of-function endocytic phenotype exhibited by the ADHD DAT coding variant, R615C. These findings reveal a unique endocytic control switch that is highly specific for DAT. Moreover, the ability to rescue the DAT(R615C) coding variant suggests that manipulating DAT trafficking mechanisms may be a potential therapeutic approach to correct DAT coding variants that exhibit trafficking dysregulation.
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91
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Fukata Y, Murakami T, Yokoi N, Fukata M. Local Palmitoylation Cycles and Specialized Membrane Domain Organization. CURRENT TOPICS IN MEMBRANES 2015; 77:97-141. [PMID: 26781831 DOI: 10.1016/bs.ctm.2015.10.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Palmitoylation is an evolutionally conserved lipid modification of proteins. Dynamic and reversible palmitoylation controls a wide range of molecular and cellular properties of proteins including the protein trafficking, protein function, protein stability, and specialized membrane domain organization. However, technical difficulties in (1) detection of palmitoylated substrate proteins and (2) purification and enzymology of palmitoylating enzymes have prevented the progress in palmitoylation research, compared with that in phosphorylation research. The recent development of proteomic and chemical biology techniques has unexpectedly expanded the known complement of palmitoylated proteins in various species and tissues/cells, and revealed the unique occurrence of palmitoylated proteins in membrane-bound organelles and specific membrane compartments. Furthermore, identification and characterization of DHHC (Asp-His-His-Cys) palmitoylating enzyme-substrate pairs have contributed to elucidating the regulatory mechanisms and pathophysiological significance of protein palmitoylation. Here, we review the recent progress in protein palmitoylation at the molecular, cellular, and in vivo level and discuss how locally regulated palmitoylation machinery works for dynamic nanoscale organization of membrane domains.
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Affiliation(s)
- Yuko Fukata
- Division of Membrane Physiology, Department of Cell Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan; Department of Physiological Sciences, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan
| | - Tatsuro Murakami
- Division of Membrane Physiology, Department of Cell Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan; Department of Physiological Sciences, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan
| | - Norihiko Yokoi
- Division of Membrane Physiology, Department of Cell Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan; Department of Physiological Sciences, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan
| | - Masaki Fukata
- Division of Membrane Physiology, Department of Cell Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan; Department of Physiological Sciences, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan
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92
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Insights in how amphetamine ROCKs (Rho-associated containing kinase) membrane protein trafficking. Proc Natl Acad Sci U S A 2015; 112:15538-9. [PMID: 26607447 DOI: 10.1073/pnas.1520960112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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93
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Khelashvili G, Stanley N, Sahai MA, Medina J, LeVine MV, Shi L, De Fabritiis G, Weinstein H. Spontaneous inward opening of the dopamine transporter is triggered by PIP2-regulated dynamics of the N-terminus. ACS Chem Neurosci 2015; 6:1825-37. [PMID: 26255829 PMCID: PMC4653762 DOI: 10.1021/acschemneuro.5b00179] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
![]()
We
present the dynamic mechanism of concerted motions in a full-length
molecular model of the human dopamine transporter (hDAT), a member
of the neurotransmitter/sodium symporter (NSS) family, involved in
state-to-state transitions underlying function. The findings result
from an analysis of unbiased atomistic molecular dynamics simulation
trajectories (totaling >14 μs) of the hDAT molecule immersed
in lipid membrane environments with or without phosphatidylinositol
4,5-biphosphate (PIP2) lipids. The N-terminal region of
hDAT (N-term) is shown to have an essential mechanistic role in correlated
rearrangements of specific structural motifs relevant to state-to-state
transitions in the hDAT. The mechanism involves PIP2-mediated
electrostatic interactions between the N-term and the intracellular
loops of the transporter molecule. Quantitative analyses of collective
motions in the trajectories reveal that these interactions correlate
with the inward-opening dynamics of hDAT and are allosterically coupled
to the known functional sites of the transporter. The observed large-scale
motions are enabled by specific reconfiguration of the network of
ionic interactions at the intracellular end of the protein. The isomerization
to the inward-facing state in hDAT is accompanied by concomitant movements
in the extracellular vestibule and results in the release of an Na+ ion from the Na2 site and destabilization of the substrate
dopamine in the primary substrate binding S1 site. The dynamic mechanism
emerging from the findings highlights the involvement of the PIP2-regulated interactions between the N-term and the intracellular
loop 4 in the functionally relevant conformational transitions that
are also similar to those found to underlie state-to-state transitions
in the leucine transporter (LeuT), a prototypical bacterial homologue
of the NSS.
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Affiliation(s)
- George Khelashvili
- Department
of Physiology and Biophysics, Weill Cornell Medical College of Cornell University (WCMC), New York, New York 10065, United States
| | - Nathaniel Stanley
- Computational
Biophysics Laboratory (GRIB-IMIM), Universitat Pompeu Fabra, Barcelona
Biomedical Research Park (PRBB), C/Doctor Aiguader 88, 08003 Barcelona, Spain
| | - Michelle A. Sahai
- Department
of Physiology and Biophysics, Weill Cornell Medical College of Cornell University (WCMC), New York, New York 10065, United States
| | - Jaime Medina
- Department
of Physiology and Biophysics, Weill Cornell Medical College of Cornell University (WCMC), New York, New York 10065, United States
| | - Michael V. LeVine
- Department
of Physiology and Biophysics, Weill Cornell Medical College of Cornell University (WCMC), New York, New York 10065, United States
| | - Lei Shi
- Department
of Physiology and Biophysics, Weill Cornell Medical College of Cornell University (WCMC), New York, New York 10065, United States
- HRH
Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute of Computational
Biomedicine, Weill Cornell Medical College of Cornell University, New York, New York 10065, United States
| | - Gianni De Fabritiis
- Computational
Biophysics Laboratory (GRIB-IMIM), Universitat Pompeu Fabra, Barcelona
Biomedical Research Park (PRBB), C/Doctor Aiguader 88, 08003 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats, Passeig Lluis Companys 23, 08010 Barcelona, Spain
| | - Harel Weinstein
- Department
of Physiology and Biophysics, Weill Cornell Medical College of Cornell University (WCMC), New York, New York 10065, United States
- HRH
Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute of Computational
Biomedicine, Weill Cornell Medical College of Cornell University, New York, New York 10065, United States
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94
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Butler B, Saha K, Rana T, Becker JP, Sambo D, Davari P, Goodwin JS, Khoshbouei H. Dopamine Transporter Activity Is Modulated by α-Synuclein. J Biol Chem 2015; 290:29542-54. [PMID: 26442590 DOI: 10.1074/jbc.m115.691592] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Indexed: 12/24/2022] Open
Abstract
The duration and strength of the dopaminergic signal are regulated by the dopamine transporter (DAT). Drug addiction and neurodegenerative and neuropsychiatric diseases have all been associated with altered DAT activity. The membrane localization and the activity of DAT are regulated by a number of intracellular proteins. α-Synuclein, a protein partner of DAT, is implicated in neurodegenerative disease and drug addiction. Little is known about the regulatory mechanisms of the interaction between DAT and α-synuclein, the cellular location of this interaction, and the functional consequences of this interaction on the basal, amphetamine-induced DAT-mediated dopamine efflux, and membrane microdomain distribution of the transporter. Here, we found that the majority of DAT·α-synuclein protein complexes are found at the plasma membrane of dopaminergic neurons or mammalian cells and that the amphetamine-mediated increase in DAT activity enhances the association of these proteins at the plasma membrane. Further examination of the interaction of DAT and α-synuclein revealed a transient interaction between these two proteins at the plasma membrane. Additionally, we found DAT-induced membrane depolarization enhances plasma membrane localization of α-synuclein, which in turn increases dopamine efflux and enhances DAT localization in cholesterol-rich membrane microdomains.
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Affiliation(s)
- Brittany Butler
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Kaustuv Saha
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Tanu Rana
- the Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, Tennessee 37208
| | - Jonas P Becker
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Danielle Sambo
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Paran Davari
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - J Shawn Goodwin
- the Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, Tennessee 37208
| | - Habibeh Khoshbouei
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
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95
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Vanderwerf SM, Buck DC, Wilmarth PA, Sears LM, David LL, Morton DB, Neve KA. Role for Rab10 in Methamphetamine-Induced Behavior. PLoS One 2015; 10:e0136167. [PMID: 26291453 PMCID: PMC4546301 DOI: 10.1371/journal.pone.0136167] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 07/31/2015] [Indexed: 11/18/2022] Open
Abstract
Lipid rafts are specialized, cholesterol-rich membrane compartments that help to organize transmembrane signaling by restricting or promoting interactions with subsets of the cellular proteome. The hypothesis driving this study was that identifying proteins whose relative abundance in rafts is altered by the abused psychostimulant methamphetamine would contribute to fully describing the pathways involved in acute and chronic effects of the drug. Using a detergent-free method for preparing rafts from rat brain striatal membranes, we identified density gradient fractions enriched in the raft protein flotillin but deficient in calnexin and the transferrin receptor, markers of non-raft membranes. Dopamine D1- and D2-like receptor binding activity was highly enriched in the raft fractions, but pretreating rats with methamphetamine (2 mg/kg) once or repeatedly for 11 days did not alter the distribution of the receptors. LC-MS analysis of the protein composition of raft fractions from rats treated once with methamphetamine or saline identified methamphetamine-induced changes in the relative abundance of 23 raft proteins, including the monomeric GTP-binding protein Rab10, whose abundance in rafts was decreased 2.1-fold by acute methamphetamine treatment. Decreased raft localization was associated with a selective decrease in the abundance of Rab10 in a membrane fraction that includes synaptic vesicles and endosomes. Inhibiting Rab10 activity by pan-neuronal expression of a dominant-negative Rab10 mutant in Drosophila melanogaster decreased methamphetamine-induced activity and mortality and decreased caffeine-stimulated activity but not mortality, whereas inhibiting Rab10 activity selectively in cholinergic neurons had no effect. These results suggest that activation and redistribution of Rab10 is critical for some of the behavioral effects of psychostimulants.
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Affiliation(s)
- Scott M. Vanderwerf
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon, United States of America
- Department of Integrative Biosciences, Oregon Health & Science University, Portland, Oregon, United States of America
| | - David C. Buck
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Phillip A. Wilmarth
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Leila M. Sears
- Department of Integrative Biosciences, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Larry L. David
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - David B. Morton
- Department of Integrative Biosciences, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Kim A. Neve
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon, United States of America
- Research Service, VA Portland Health Care System, Portland, Oregon, United States of America
- * E-mail:
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96
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Identification of a Vav2-dependent mechanism for GDNF/Ret control of mesolimbic DAT trafficking. Nat Neurosci 2015; 18:1084-93. [PMID: 26147533 DOI: 10.1038/nn.4060] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 06/11/2015] [Indexed: 11/08/2022]
Abstract
Dopamine (DA) homeostasis is essential for a variety of brain activities. Dopamine transporter (DAT)-mediated DA reuptake is one of the most critical mechanisms for normal DA homeostasis. However, the molecular mechanisms underlying the regulation of DAT activity in the brain remain poorly understood. Here we show that the Rho-family guanine nucleotide exchange factor protein Vav2 is required for DAT cell surface expression and transporter activity modulated by glial cell line-derived neurotrophic factor (GDNF) and its cognate receptor Ret. Mice deficient in either Vav2 or Ret displayed elevated DAT activity, which was accompanied by an increase in intracellular DA selectively in the nucleus accumbens. Vav2(-/-) mice exposed to cocaine showed reduced DAT activity and diminished behavioral cocaine response. Our data demonstrate that Vav2 is a determinant of DAT trafficking in vivo and contributes to the maintenance of DA homeostasis in limbic DA neuron terminals.
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97
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Crisafulli C, Drago A, Calabrò M, Spina E, Serretti A. A molecular pathway analysis informs the genetic background at risk for schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 2015; 59:21-30. [PMID: 25554435 DOI: 10.1016/j.pnpbp.2014.12.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/22/2014] [Accepted: 12/23/2014] [Indexed: 01/01/2023]
Abstract
BACKGROUND Schizophrenia is a complex mental disorder marked by severely impaired thinking, delusional thoughts, hallucinations and poor emotional responsiveness. The biological mechanisms that lead to schizophrenia may be related to the genetic background of patients. Thus, a genetic perspective may help to unravel the molecular pathways disrupted in schizophrenia. METHODS In the present work, we used a molecular pathway analysis to identify the molecular pathways associated with schizophrenia. We collected data of genetic loci previously associated with schizophrenia, identified the genes located in those positions and created the metabolic pathways that are related to those genes' products. These pathways were tested for enrichment (a number of SNPs associated with the phenotype significantly higher than expected by chance) in a sample of schizophrenic patients and controls (4486 and 4477, respectively). RESULTS The molecular pathway that resulted from the identification of all the genes located in the loci previously found to be associated with schizophrenia was found to be enriched, as expected (permutated p(10(6))=9.9999e-06).We found 60 SNPs amongst 30 different genes with a strong association with schizophrenia. The genes are related to the pathways related to neurodevelopment, apoptosis, vesicle traffic, immune response and MAPK cascade. CONCLUSIONS The pathway related to the toll-like receptor family seemed to play a central role in the modulation/connection of various pathways whose disruption leads to schizophrenia. This pathway is related to the innate immune system, further stressing the role of immunological-related events in increasing the risk to schizophrenia.
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Affiliation(s)
- Concetta Crisafulli
- Department of Biomedical Science and Morphological and Functional Images, University of Messina, Messina, Italy
| | - Antonio Drago
- Department of Biomedical and Neuromotor Sciences - DIBINEM, University of Bologna, Bologna, Italy; I.R.C.C.S. "San Giovanni di Dio", Fatebenefratelli, Brescia, Italy.
| | - Marco Calabrò
- Department of Biomedical Science and Morphological and Functional Images, University of Messina, Messina, Italy; Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy; IRCCS Centro Neurolesi "Bonino-Pulejo", Messina, Italy
| | - Edoardo Spina
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Alessandro Serretti
- Department of Biomedical and Neuromotor Sciences - DIBINEM, University of Bologna, Bologna, Italy
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98
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Jang D, Kwon H, Jeong K, Lee J, Pak Y. Essential role of flotillin-1 palmitoylation in the intracellular localization and signaling function of IGF-1 receptor. J Cell Sci 2015; 128:2179-90. [PMID: 25908865 DOI: 10.1242/jcs.169409] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 04/14/2015] [Indexed: 12/21/2022] Open
Abstract
Here, we explored flotillin-1-mediated regulation of insulin-like growth factor-1 (IGF-1) signaling. Flotillin-1-deficient cells exhibited a reduction in the activation of IGF-1 receptor (IGF-1R), ERK1/2 and Akt pathways, and the transcriptional activation of Elk-1 and the proliferation in response to IGF-1 were reduced in these cells. We found that IGF-1-independent flotillin-1 palmitoylation at Cys34 in the endoplasmic reticulum (ER) was required for the ER exit and the plasma membrane localization of flotillin-1 and IGF-1R. IGF-1-dependent depalmitoylation and repalmitoylation of flotillin-1 sustained tyrosine kinase activation of the plasma-membrane-targeted IGF-1R. Dysfunction and blocking the turnover of flotillin-1 palmitoylation abrogated cancer cell proliferation after IGF-1R signaling activation. Our data show that flotillin-1 palmitoylation is a new mechanism by which the intracellular localization and activation of IGF-1R are controlled.
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Affiliation(s)
- Donghwan Jang
- Division of Life Science, Graduate School of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea
| | - Hayeong Kwon
- Division of Life Science, Graduate School of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea
| | - Kyuho Jeong
- Division of Life Science, Graduate School of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea
| | - Jaewoong Lee
- Division of Life Science, Graduate School of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea
| | - Yunbae Pak
- Division of Life Science, Graduate School of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 660-701, Korea
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99
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Kovtun O, Sakrikar D, Tomlinson ID, Chang JC, Arzeta-Ferrer X, Blakely RD, Rosenthal SJ. Single-quantum-dot tracking reveals altered membrane dynamics of an attention-deficit/hyperactivity-disorder-derived dopamine transporter coding variant. ACS Chem Neurosci 2015; 6:526-34. [PMID: 25747272 PMCID: PMC5530757 DOI: 10.1021/cn500202c] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The presynaptic, cocaine- and amphetamine-sensitive dopamine (DA) transporter (DAT, SLC6A3) controls the intensity and duration of synaptic dopamine signals by rapid clearance of DA back into presynaptic nerve terminals. Abnormalities in DAT-mediated DA clearance have been linked to a variety of neuropsychiatric disorders, including addiction, autism, and attention deficit/hyperactivity disorder (ADHD). Membrane trafficking of DAT appears to be an important, albeit incompletely understood, post-translational regulatory mechanism; its dysregulation has been recently proposed as a potential risk determinant of these disorders. In this study, we demonstrate a link between an ADHD-associated DAT mutation (Arg615Cys, R615C) and variation on DAT transporter cell surface dynamics, a combination only previously studied with ensemble biochemical and optical approaches that featured limited spatiotemporal resolution. Here, we utilize high-affinity, DAT-specific antagonist-conjugated quantum dot (QD) probes to establish the dynamic mobility of wild-type and mutant DATs at the plasma membrane of living cells. Single DAT-QD complex trajectory analysis revealed that the DAT 615C variant exhibited increased membrane mobility relative to DAT 615R, with diffusion rates comparable to those observed after lipid raft disruption. This phenomenon was accompanied by a loss of transporter mobilization triggered by amphetamine, a common component of ADHD medications. Together, our data provides the first dynamic imaging of single DAT proteins, providing new insights into the relationship between surface dynamics and trafficking of both wild-type and disease-associated transporters. Our approach should be generalizable to future studies that explore the possibilities of perturbed surface DAT dynamics that may arise as a consequence of genetic alterations, regulatory changes, and drug use that contribute to the etiology or treatment of neuropsychiatric disorders.
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Affiliation(s)
- Oleg Kovtun
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
- McCoy & McCoy Laboratories, Inc, Madisonville, Kentucky 42431, United States
| | - Dhananjay Sakrikar
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Ian D. Tomlinson
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Jerry C. Chang
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York 10065, United States
| | - Xochitl Arzeta-Ferrer
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Randy D. Blakely
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Psychiatry, Vanderbilt University, Nashville, Tennessee 37235, United States
- Silvio O. Conte Center for Neuroscience Research, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Sandra J. Rosenthal
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, United States
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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100
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Functional mechanisms of neurotransmitter transporters regulated by lipid-protein interactions of their terminal loops. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1765-74. [PMID: 25847498 DOI: 10.1016/j.bbamem.2015.03.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/16/2015] [Accepted: 03/23/2015] [Indexed: 01/28/2023]
Abstract
The physiological functions of neurotransmitter:sodium symporters (NSS) in reuptake of neurotransmitters from the synapse into the presynaptic nerve have been shown to be complemented by their involvement, together with non-plasma membrane neurotransmitter transporters, in the reverse transport of substrate (efflux) in response to psychostimulants. Recent experimental evidence implicates highly anionic phosphatidylinositol 4,5-biphosphate (PIP(2)) lipids in such functions of the serotonin (SERT) and dopamine (DAT) transporters. Thus, for both SERT and DAT, neurotransmitter efflux has been shown to be strongly regulated by the presence of PIP(2) lipids in the plasma membrane, and the electrostatic interaction of the N-terminal region of DAT with the negatively charged PIP(2) lipids. We examine the experimentally established phenotypes in a structural context obtained from computational modeling based on recent crystallographic data. The results are shown to set the stage for a mechanistic understanding of physiological actions of neurotransmitter transporters in the NSS family of membrane proteins. This article is part of a Special Issue entitled: Lipid-protein interactions.
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