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Brown CR, Shetty M, Foster JD. Palmitoylation regulates norepinephrine transporter uptake, surface localization, and total expression with pathogenic implications in postural orthostatic tachycardia syndrome. J Neurochem 2025; 169:e16241. [PMID: 39395208 PMCID: PMC11808474 DOI: 10.1111/jnc.16241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 09/21/2024] [Accepted: 09/24/2024] [Indexed: 10/14/2024]
Abstract
Postural orthostatic tachycardia syndrome (POTS) is an adrenergic signaling disorder characterized by excessive plasma norepinephrine, postural tachycardia, and syncope. The norepinephrine transporter (NET) modulates adrenergic homeostasis via the reuptake of extracellular catecholamines and is implicated in the pathogenesis of adrenergic and neurological disorders. In this study, we reveal NET is palmitoylated in male Sprague-Dawley rats and Lilly Laboratory Cell Porcine Kidney (LLC-PK1) cells. S-palmitoylation, or the addition of a 16-carbon saturated fatty acid, is a reversible post-translational modification responsible for the regulation of numerous biological mechanisms. We found that LLC-PK1 NET is dynamically palmitoylated, and that inhibition with the palmitoyl acyltransferase (DHHC) inhibitor, 2-bromopalmitate (2BP) results in decreased NET palmitoylation within 90 min of treatment. This result was followed closely by a reduction in transport capacity, cell surface, and total cellular NET expression after 120 min of treatment. Increasing 2BP concentrations and treatment time revealed a nearly complete loss of total NET protein. Co-expression with individual DHHCs revealed a single DHHC enzyme, DHHC1, promoted wild-type (WT) hNET palmitoylation and elevated NET protein levels. The POTS-associated NET mutant, A457P, exhibits dramatically decreased transport capacity and cell surface levels which we have confirmed in the current study. In an attempt to recover A457P NET expression, we co-expressed the A457P variant with DHHC1 to drive expression as seen with the WT protein but instead saw an increase in NET N-terminal immuno-detectable forms and fragments. Elimination of a potential palmitoylation site at cysteine 44 in the N-terminal tail of hNET resulted in a low expression phenotype mimicking the A457P hNET variant. Further investigation of A457P NET palmitoylation and surface expression is necessary, but our preliminary novel findings reveal palmitoylation as a mechanism of NET regulation and suggest that dysregulation of this process may contribute to the pathogenesis of adrenergic disorders like POTS.
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Affiliation(s)
- Christopher R. Brown
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNorth DakotaUSA
| | - Madhur Shetty
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNorth DakotaUSA
| | - James D. Foster
- Department of Biomedical SciencesUniversity of North Dakota School of Medicine and Health SciencesGrand ForksNorth DakotaUSA
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Brown CR, Foster JD. Palmitoylation regulates norepinephrine transporter trafficking and expression and is potentially involved in the pathogenesis of postural orthostatic tachycardia syndrome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.22.586171. [PMID: 38585862 PMCID: PMC10996475 DOI: 10.1101/2024.03.22.586171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Postural orthostatic tachycardia syndrome (POTS) is an adrenergic signaling disorder characterized by excessive plasma norepinephrine, postural tachycardia, and syncope. The norepinephrine transporter (NET) modulates adrenergic homeostasis via reuptake of extracellular catecholamines and is implicated in the pathogenesis of adrenergic and neurological disorders. Previous research has outlined that NET activity and trafficking is modulated via reversible post-translational modifications like phosphorylation and ubiquitylation. S-palmitoylation, or the addition of a 16-carbon saturated fatty acid, is another post-translational modification responsible for numerous biological mechanisms. In this study, we reveal that NET is dynamically palmitoylated and inhibition of this modification with the palmitoyl acyltransferase (DHHC) inhibitor, 2-bromopalmitate (2BP), results in decreased NET palmitoylation within 90 min of treatment. This result was followed closely with a reduction in transport capacity, cell surface, and total cellular NET expression after 120 min of treatment. Increasing 2BP concentrations and treatment time revealed a nearly complete loss of total NET protein. Co-expression with individual DHHCs revealed a single DHHC enzyme, DHHC1, promoted WT hNET palmitoylation and elevated NET protein levels. The POTS associated NET mutant, A457P, exhibits dramatically decreased transport capacity and cell surface levels which we have confirmed in the current study. In an attempt to recover A457P NET expression we co-expressed the A457P variant with DHHC1 to drive expression as seen with the WT protein but instead saw an increase in NET N-terminal immuno-detectable fragments. Further investigation of A457P NET palmitoylation and surface expression is necessary, but our preliminary novel findings reveal palmitoylation as a mechanism of NET regulation and suggest that dysregulation of this process may contribute to the pathogenesis of POTS.
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Blunted Amphetamine-induced Reinforcing Behaviors and Transporter Downregulation in Knock-in Mice Carrying Alanine Mutations at Threonine-258 and Serine-259 of Norepinephrine Transporter. J Mol Neurosci 2022; 72:1965-1976. [DOI: 10.1007/s12031-022-01988-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 01/12/2022] [Indexed: 10/17/2022]
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Goetzl L, Darbinian N, Merabova N, Devane LC, Ramamoorthy S. Gestational Age Variation in Human Placental Drug Transporters. Front Pharmacol 2022; 13:837694. [PMID: 35462922 PMCID: PMC9019509 DOI: 10.3389/fphar.2022.837694] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 01/24/2022] [Indexed: 12/29/2022] Open
Abstract
Patient and providers’ fear of fetal exposure to medications may lead to discontinuation of treatment, disease relapse, and maternal morbidity. Placental drug transporters play a critical role in fetal exposure through active transport but the majority of data are limited to the 3rd trimester, when the majority of organogenesis has already occurred. Our objective was to define gestational age (GA) dependent changes in protein activity, expression and modifications of five major placental drug transporters: SERT, P-gp, NET, BCRP and MRP3. Apical brush border membrane fractions were prepared from fresh 1st, 2nd and 3rd trimester human placentas collected following elective pregnancy termination or planned cesarean delivery. A structured maternal questionnaire was used to identify maternal drug use and exclude exposed subjects. Changes in placental transporter activity and expression relative to housekeeping proteins were quantified. There was evidence for strong developmental regulation of SERT, NET, P-gp, BCRP and MRP3. P-gp and BCRP decreased with gestation (r = −0.72, p < 0.001 and r = −0.77, p < 0.001, respectively). Total SERT increased with gestation but this increase was due to a decrease in SERT cleavage products across trimesters. Uncleaved SERT increased with GA (r = 0.89, p < 0.001) while cleaved SERT decreased with GA (r = −0.94, p < 0.001). Apical membrane NET overall did not appear to be developmentally regulated (r = −0.08, p = 0.53). Two forms of MRP3 were identified; the 50 kD form did not change across GA; the 160 kD form was steady in the 1st and 2nd trimester and increased in the 3rd trimester (r = 0.24, p = 0.02). The 50 kD form was expressed at higher levels. The observed patterns of SERT, NET P-gp, BCRP and MRP3 expression and activity may be associated with transporter activity or decreased placental permeability in the 1st trimester to transporter specific substrates including commonly used psychoactive medications such as anti-depressants, anti-psychotics, and amphetamines, while transport of nutrients and serotonin is important in the 1st trimester. Overall these observations are consistent with a strong protective effect during organogenesis. 3rd trimester estimates of fetal exposure obtained from cord blood likely significantly overestimate early fetal exposure to these medications at any fixed maternal dose.
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Mannangatti P, Ragu Varman D, Ramamoorthy S, Jayanthi LD. Neurokinin-1 Antagonism Distinguishes the Role of Norepinephrine Transporter from Dopamine Transporter in Mediating Amphetamine Behaviors. Pharmacology 2021; 106:597-605. [PMID: 34515205 DOI: 10.1159/000518033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 06/21/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND Amphetamine (AMPH) and other psychostimulants act on the norepinephrine (NE) transporter (NET) and the dopamine (DA) transporter (DAT) and enhance NE and DA signaling. Both NET and DAT share anatomical and functional characteristics and are regulated similarly by psychostimulants and receptor-linked signaling pathways. We and others have demonstrated that NET and DAT are downregulated by AMPH and substance P/neurokinin-1 receptor (NK1R)-mediated protein kinase C pathway. OBJECTIVES Since both NET and DAT are downregulated by AMPH and NK1R activation and share high sequence homology, the objective of the study was to determine the catecholamine transporter specificity in NK1R modulation of AMPH-induced behaviors. METHODS The effect of NK1R antagonism on AMPH-induced conditioned place preference (CPP) as well as AMPH-induced NET and DAT downregulation was examined using NET and DAT knockout mice (NET-KO and DAT-KO) along with their wild-type littermates. RESULTS Aprepitant (5 mg/kg i.p.) significantly attenuated AMPH (2 mg/kg i.p.)-induced CPP in the wild-type and DAT-KO but not in the NET-KO. Locomotor activity measured during the post-conditioning test (in the absence of AMPH) showed higher locomotor activity in DAT-KO compared to wild-type or NET-KO. However, the locomotor activity of all 3 genotypes remained unchanged following aprepitant. Additionally, in the ventral striatum of wild-type, the AMPH-induced downregulation of NET function and surface expression but not that of DAT was attenuated by aprepitant. CONCLUSIONS The results from the current study demonstrate that aprepitant attenuates the expression of AMPH-induced CPP in DAT-KO mice but not in NET-KO mice suggesting a role for NK1R-mediated NET regulation in AMPH-induced behaviors.
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Affiliation(s)
- Padmanabhan Mannangatti
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Durairaj Ragu Varman
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Sammanda Ramamoorthy
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Lankupalle D Jayanthi
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia, USA
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Mannangatti P, Ramamoorthy S, Jayanthi LD. Interference of norepinephrine transporter trafficking motif attenuates amphetamine-induced locomotor hyperactivity and conditioned place preference. Neuropharmacology 2017; 128:132-141. [PMID: 28986281 DOI: 10.1016/j.neuropharm.2017.10.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/15/2017] [Accepted: 10/03/2017] [Indexed: 11/28/2022]
Abstract
Amphetamine (AMPH)-mediated norepinephrine transporter (NET) downregulation requires NET-T258/S259 trafficking motif. The present study utilizes cell permeable NET-T258/S259 motif interfering peptide, which blocks AMPH-induced NET downregulation, to explore the role of this form of NET regulation in AMPH-mediated behaviors. In rats receiving intra-accumbal microinjections of TAT-conjugated peptides encompassing NET-T258/S259 motif, acute systemic AMPH failed to inhibit NE transport in the TAT-NET-T258/S259 wild-type (WT) peptide injected hemisphere but not in the vehicle or scrambled peptide injected hemisphere. Acute AMPH-induced hyperactivity was significantly reduced in rats receiving intra-accumbal TAT-NET-T258/S259 WT peptide compared to those receiving intra-accumbal vehicle or TAT-NET-T258A/S259A mutant peptide or corresponding TAT-conjugated scrambled peptide. Basal locomotor activity was not altered by peptide infusions alone. Similarly AMPH-induced locomotor sensitization was significantly reduced in rats receiving intra-accumbal TAT-NET-T258/S259 WT peptide prior to AMPH challenge and not in rats receiving the mutant or scrambled peptide. In conditioned place preference (CPP) paradigm, a single bilateral intra-accumbal microinjection of TAT-NET-T258/S259 WT peptide prior to CPP testing significantly reduced AMPH-induced CPP expression. Likewise, a single bilateral intra-accumbal microinjection of TAT-NET-T258/S259 WT peptide prior to drug-challenge significantly attenuated AMPH-primed CPP reinstatement. On the other hand, bilateral intra-accumbal microinjection of scrambled peptide did not affect AMPH-induced CPP expression or reinstatement. These data demonstrate a role for T258/S259-dependent NET regulation in AMPH-induced hyperactivity and sensitization as well as AMPH-induced CPP expression and reinstatement.
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Affiliation(s)
- Padmanabhan Mannangatti
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Sammanda Ramamoorthy
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
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Mannangatti P, Sundaramurthy S, Ramamoorthy S, Jayanthi LD. Differential effects of aprepitant, a clinically used neurokinin-1 receptor antagonist on the expression of conditioned psychostimulant versus opioid reward. Psychopharmacology (Berl) 2017; 234:695-705. [PMID: 28013351 PMCID: PMC5266628 DOI: 10.1007/s00213-016-4504-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 12/08/2016] [Indexed: 01/29/2023]
Abstract
RATIONALE Neurokinin-1 receptor (NK1R) signaling modulates behaviors associated with psychostimulants and opioids. Psychostimulants, such as amphetamine (AMPH) and cocaine, bind to monoamine transporters and alter their functions. Both dopamine and norepinephrine transporters are regulated by NK1R activation suggesting a role for NK1R mediated catecholamine transporter regulation in psychostimulant-mediated behaviors. OBJECTIVES The effect of in vivo administration of aprepitant (10 mg/kg) on the expression of AMPH (0.5 and 2 mg/kg) and cocaine (5 and 20 mg/kg)-induced conditioned place preference (CPP) as well as locomotor activation was examined in C57BL/6J mice. The effect of aprepitant on morphine (1 and 5 mg/kg)-induced CPP was also examined to identify the specific actions of aprepitant on psychostimulant versus opioid-induced behaviors. RESULTS Aprepitant administration significantly attenuated the CPP expression and locomotor activation produced by AMPH and cocaine. In contrast, aprepitant significantly enhanced the expression of CPP produced by morphine while significantly suppressing the locomotor activity of the mice conditioned with morphine. Aprepitant by itself did not induce significant CPP or conditioned place aversion or locomotor activation or suppression. CONCLUSIONS Attenuation of AMPH or cocaine-induced CPP and locomotor activation by aprepitant suggests a role for NK1R signaling in psychostimulant-mediated behaviors. Stimulation of morphine-induced CPP expression and suppression of locomotor activity of morphine-conditioned mice suggest differential effects of NK1R antagonism on conditioned psychostimulant versus opioid reward. Collectively, these findings indicate that clinically used NK1R antagonist, aprepitant may serve as a potential therapeutic agent in the treatment of psychostimulant abuse.
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Affiliation(s)
| | | | | | - Lankupalle D Jayanthi
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, 23298, USA.
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Sung U, Binda F, Savchenko V, Owens WA, Daws LC. Ca 2+ dependent surface trafficking of norepinephrine transporters depends on threonine 30 and Ca 2+ calmodulin kinases. J Chem Neuroanat 2016; 83-84:19-35. [PMID: 28017803 DOI: 10.1016/j.jchemneu.2016.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 12/09/2016] [Accepted: 12/15/2016] [Indexed: 11/28/2022]
Abstract
The antidepressant-sensitive norepinephrine (NE) transporter (NET) inactivates NE released during central and peripheral neuronal activity by transport into presynaptic cells. Altered NE clearance due to dysfunction of NET has been associated with the development of mental illness and cardiovascular diseases. NET activity in vivo is influenced by stress, neuronal activity, hormones and drugs. We investigated the mechanisms of Ca2+ regulation of NET and found that Ca2+ influenced both Vmax and Km for NE transport into cortical synaptosomes. Changes in extracellular Ca2+ triggered rapid and bidirectional surface trafficking of NET expressed in cultured cells. Deletion of residues 28-47 in the NET NH2-terminus abolished the Ca2+ effect on surface trafficking. Mutagenesis studies identified Thr30 in this region as the essential residue for both Ca2+- dependent phosphorylation and trafficking of NET. Depolarization of excitable cells increased surface NET in a Thr30 dependent manner. A proteomic analysis, RNA interference, and pharmacological inhibition supported roles of CaMKI and CaMKII in Ca2+-modulated NE transport and NET trafficking. Depolarization of primary noradrenergic neurons in culture with elevated K+ increased NET surface expression in a process that required external Ca2+ and depended on CaMK activity. Hippocampal NE clearance in vivo was also stimulated by depolarization, and inhibitors of CaMK signaling prevented this stimulation. In summary, Ca2+ signaling influenced surface trafficking of NET through a CaMK-dependent mechanism requiring Thr30.
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Affiliation(s)
- Uhna Sung
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232-8548, United States.
| | - Francesca Binda
- Institute of Cellular and Integrative Neurosciences, CNRS, Strasbourg, France
| | - Valentina Savchenko
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232-8548, United States
| | - William A Owens
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, United States
| | - Lynette C Daws
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, United States.
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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: 73] [Impact Index Per Article: 8.1] [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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Khan AW, Corcoran SJ, Esler M, El-Osta A. Epigenomic changes associated with impaired norepinephrine transporter function in postural tachycardia syndrome. Neurosci Biobehav Rev 2016; 74:342-355. [PMID: 27345145 DOI: 10.1016/j.neubiorev.2016.06.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 06/05/2016] [Accepted: 06/15/2016] [Indexed: 01/20/2023]
Abstract
The postural tachycardia syndrome (POTS) is characterised clinically by symptoms of light-headedness, palpitations, fatigue and exercise intolerance occurring with standing and relieved by lying down. Symptoms occur in association with an inappropriate rise in heart rate in the absence of a fall in blood pressure with the assumption of standing. The pathophysiology of POTS is complicated and poorly understood. Plasma norepinephrine (NE) is often elevated in patients with POTS, resulting in consideration of dysfunction of the norepinephrine transporter (NET) encoded by SLC6A2 gene. Whilst some studies have implicated a defect in the SLC6A2 gene, the cause of reduced SLC6A2 expression and function remains unclear. The search to explain the molecular mechanism of NET dysfunction has focused on genetic variation in the SLC6A2 gene and remains inconclusive. More recent studies show epigenetic mechanisms implicated in the regulation of SLC6A2 expression. In this article, we discuss the epigenetic mechanisms involved in SLC6A2 repression and highlight the potential therapeutic application of targeting these mechanisms in POTS.
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Affiliation(s)
- Abdul Waheed Khan
- Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria 3004, Australia; Department of Pathology, The University of Melbourne, Parkville, Victoria, Australia.
| | - Susan J Corcoran
- Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria 3004, Australia.
| | - Murray Esler
- Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria 3004, Australia.
| | - Assam El-Osta
- Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria 3004, Australia; Department of Pathology, The University of Melbourne, Parkville, Victoria, Australia; Central Clinical School, Faculty of Medicine, Monash University, Victoria, Australia.
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Vuorenpää A, Jørgensen TN, Newman AH, Madsen KL, Scheinin M, Gether U. Differential Internalization Rates and Postendocytic Sorting of the Norepinephrine and Dopamine Transporters Are Controlled by Structural Elements in the N Termini. J Biol Chem 2016; 291:5634-5651. [PMID: 26786096 DOI: 10.1074/jbc.m115.702050] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Indexed: 11/06/2022] Open
Abstract
The norepinephrine transporter (NET) mediates reuptake of synaptically released norepinephrine in central and peripheral noradrenergic neurons. The molecular processes governing availability of NET in the plasma membrane are poorly understood. Here we use the fluorescent cocaine analogue JHC 1-64, as well as several other approaches, to investigate the trafficking itinerary of NET in live noradrenergic neurons. Confocal imaging revealed extensive constitutive internalization of JHC 1-64-labeled NET in the neuronal somata, proximal extensions and presynaptic boutons. Phorbol 12-myristate 13-acetate increased intracellular accumulation of JHC 1-64-labeled NET and caused a parallel reduction in uptake capacity. Internalized NET strongly colocalized with the "long loop" recycling marker Rab11, whereas less overlap was seen with the "short loop" recycling marker Rab4 and the late endosomal marker Rab7. Moreover, mitigating Rab11 function by overexpression of dominant negative Rab11 impaired NET function. Sorting of NET to the Rab11 recycling compartment was further supported by confocal imaging and reversible biotinylation experiments in transfected differentiated CATH.a cells. In contrast to NET, the dopamine transporter displayed markedly less constitutive internalization and limited sorting to the Rab11 recycling compartment in the differentiated CATH.a cells. Exchange of domains between the two homologous transporters revealed that this difference was determined by non-conserved structural elements in the intracellular N terminus. We conclude that NET displays a distinct trafficking itinerary characterized by continuous shuffling between the plasma membrane and the Rab11 recycling compartment and that the functional integrity of the Rab11 compartment is critical for maintaining proper presynaptic NET function.
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Affiliation(s)
- Anne Vuorenpää
- From the Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, Panum Institute 18.6, University of Copenhagen, DK-2200 Copenhagen, Denmark,; the Department of Pharmacology, Drug Development, and Therapeutics, University of Turku, Turku FI-20014, Finland,; the Unit of Clinical Pharmacology, Turku University Hospital, Turku FI-20520, Finland, and
| | - Trine N Jørgensen
- From the Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, Panum Institute 18.6, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Amy H Newman
- the Medicinal Chemistry Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224
| | - Kenneth L Madsen
- From the Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, Panum Institute 18.6, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Mika Scheinin
- the Department of Pharmacology, Drug Development, and Therapeutics, University of Turku, Turku FI-20014, Finland,; the Unit of Clinical Pharmacology, Turku University Hospital, Turku FI-20520, Finland, and
| | - Ulrik Gether
- From the Molecular Neuropharmacology and Genetics Laboratory, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, Panum Institute 18.6, University of Copenhagen, DK-2200 Copenhagen, Denmark,.
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Broos N, Loonstra R, van Mourik Y, Schetters D, Schoffelmeer ANM, Pattij T, De Vries TJ. Subchronic administration of atomoxetine causes an enduring reduction in context-induced relapse to cocaine seeking without affecting impulsive decision making. Addict Biol 2015; 20:714-23. [PMID: 25056833 DOI: 10.1111/adb.12168] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Previous work has established a robust relationship between impulsivity and addiction, and revealed that impulsive decision making predisposes the vulnerability to cocaine-seeking behavior in rats. An important next step is to assess whether elevated relapse vulnerability can be treated via the reduction of impulsive decision making. Therefore, this study explored whether subchronic atomoxetine treatment can reduce relapse vulnerability by reducing impulsive decision making. Rats were trained in the delayed reward task and were subjected to 3 weeks of cocaine self-administration. Following drug self-administration, animals were divided to different experimental groups and received the noradrenaline transporter inhibitor and attention-deficit/hyperactivity disorder drug atomoxetine or vehicle subchronically for 20 days. On days 1 and 10 after treatment cessation, a context-induced reinstatement test was performed. Throughout the entire experiment, changes in impulsive decision making were continuously monitored. Subchronic treatment with atomoxetine reduced context-induced reinstatement both 1 and 10 days after treatment cessation, only in animals receiving no extinction training. Interestingly, neither subchronic nor acute atomoxetine treatments affected impulsive decision making. Our data indicate that the enduring reduction in relapse sensitivity by atomoxetine occurred independent of a reduction in impulsive decision making. Nonetheless, repeated atomoxetine administration seems a promising pharmacotherapeutical strategy to prevent relapse to cocaine seeking in abstinent drug-dependent subjects.
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Affiliation(s)
- Nienke Broos
- Department of Anatomy and Neurosciences; Neuroscience Campus Amsterdam; VU University Medical Center; Amsterdam The Netherlands
| | - Rhianne Loonstra
- Department of Anatomy and Neurosciences; Neuroscience Campus Amsterdam; VU University Medical Center; Amsterdam The Netherlands
| | - Yvar van Mourik
- Department of Anatomy and Neurosciences; Neuroscience Campus Amsterdam; VU University Medical Center; Amsterdam The Netherlands
| | - Dustin Schetters
- Department of Anatomy and Neurosciences; Neuroscience Campus Amsterdam; VU University Medical Center; Amsterdam The Netherlands
| | - Anton N. M. Schoffelmeer
- Department of Anatomy and Neurosciences; Neuroscience Campus Amsterdam; VU University Medical Center; Amsterdam The Netherlands
| | - Tommy Pattij
- Department of Anatomy and Neurosciences; Neuroscience Campus Amsterdam; VU University Medical Center; Amsterdam The Netherlands
| | - Taco J. De Vries
- Department of Anatomy and Neurosciences; Neuroscience Campus Amsterdam; VU University Medical Center; Amsterdam The Netherlands
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Onaka Y, Shintani N, Nakazawa T, Haba R, Ago Y, Wang H, Kanoh T, Hayata-Takano A, Hirai H, Nagata KY, Nakamura M, Hashimoto R, Matsuda T, Waschek JA, Kasai A, Nagayasu K, Baba A, Hashimoto H. CRTH2, a prostaglandin D2 receptor, mediates depression-related behavior in mice. Behav Brain Res 2015; 284:131-7. [DOI: 10.1016/j.bbr.2015.02.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 01/27/2015] [Accepted: 02/01/2015] [Indexed: 12/11/2022]
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Mannangatti P, NarasimhaNaidu K, Damaj MI, Ramamoorthy S, Jayanthi LD. A Role for p38 Mitogen-activated Protein Kinase-mediated Threonine 30-dependent Norepinephrine Transporter Regulation in Cocaine Sensitization and Conditioned Place Preference. J Biol Chem 2015; 290:10814-27. [PMID: 25724654 DOI: 10.1074/jbc.m114.612192] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Indexed: 01/08/2023] Open
Abstract
The noradrenergic and p38 mitogen-activated protein kinase (p38 MAPK) systems are implicated in cocaine-elicited behaviors. Previously, we demonstrated a role for p38 MAPK-mediated norepinephrine transporter (NET) Thr(30) phosphorylation in cocaine-induced NET up-regulation (Mannangatti, P., Arapulisamy, O., Shippenberg, T. S., Ramamoorthy, S., and Jayanthi, L. D. (2011) J. Biol. Chem. 286, 20239-20250). The present study explored the functional interaction between p38 MAPK-mediated NET regulation and cocaine-induced behaviors. In vitro cocaine treatment of mouse prefrontal cortex synaptosomes resulted in enhanced NET function, surface expression, and phosphorylation. Pretreatment with PD169316, a p38 MAPK inhibitor, completely blocked cocaine-mediated NET up-regulation and phosphorylation. In mice, in vivo administration of p38 MAPK inhibitor SB203580 completely blocked cocaine-induced NET up-regulation and p38 MAPK activation in the prefrontal cortex and nucleus accumbens. When tested for cocaine-induced locomotor sensitization and conditioned place preference (CPP), mice receiving SB203580 on cocaine challenge day or on postconditioning test day exhibited significantly reduced cocaine sensitization and CPP. A transactivator of transcription (TAT) peptide strategy was utilized to test the involvement of the NET-Thr(30) motif. In vitro treatment of synaptosomes with TAT-NET-Thr(30) (wild-type peptide) completely blocked cocaine-mediated NET up-regulation and phosphorylation. In vivo administration of TAT-NET-Thr(30) peptide but not TAT-NET-T30A (mutant peptide) completely blocked cocaine-mediated NET up-regulation and phosphorylation. In the cocaine CPP paradigm, mice receiving TAT-NET-Thr(30) but not TAT-NET-T30A on postconditioning test day exhibited significantly reduced cocaine CPP. Following extinction, TAT-NET-Thr(30) when given prior to cocaine challenge significantly reduced reinstatement of cocaine CPP. These results demonstrate that the direct inhibition of p38 MAPK or the manipulation of NET-Thr(30) motif/phosphorylation via a TAT peptide strategy prevents cocaine-induced NET up-regulation, locomotor sensitization, and CPP, suggesting a role for Thr(30)-linked NET regulation in cocaine-elicited behaviors.
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Affiliation(s)
- Padmanabhan Mannangatti
- From the Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia 23298
| | | | - Mohamad Imad Damaj
- From the Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia 23298
| | - Sammanda Ramamoorthy
- From the Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia 23298
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Barbosa DJ, Capela JP, de Lourdes Bastos M, Carvalho F. In vitro models for neurotoxicology research. Toxicol Res (Camb) 2015; 4:801-842. [DOI: 10.1039/c4tx00043a] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023] Open
Abstract
The nervous system has a highly complex organization, including many cell types with multiple functions, with an intricate anatomy and unique structural and functional characteristics; the study of its (dys)functionality following exposure to xenobiotics, neurotoxicology, constitutes an important issue in neurosciences.
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Affiliation(s)
- Daniel José Barbosa
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
| | - João Paulo Capela
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
| | - Maria de Lourdes Bastos
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
| | - Félix Carvalho
- REQUIMTE (Rede de Química e Tecnologia)
- Laboratório de Toxicologia
- Departamento de Ciências Biológicas
- Faculdade de Farmácia
- Universidade do Porto
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Arapulisamy O, Mannangatti P, Jayanthi LD. Regulated norepinephrine transporter interaction with the neurokinin-1 receptor establishes transporter subcellular localization. J Biol Chem 2013; 288:28599-610. [PMID: 23979140 DOI: 10.1074/jbc.m113.472878] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neurokinin-1 receptor (NK1R) mediates down-regulation of human norepinephrine (NE) transporter (hNET) via protein kinase C (PKC). However, native NET regulation by NK1R and the mechanism by which NK1R targets NET among other potential effectors are unknown. Effect of NK1R activation on native NET regulation and NET/NK1R interaction were studied using rat brain synaptosomes expressing native NET and NK1R as well as human placental trophoblast (HTR) cells coexpressing WT-hNET or NK1R/PKC-resistant hNET-T258A,S259A double mutant (NET-DM) and hNK1R. The selective NK1R agonist, GR73632, and Substance-P (SP) inhibited NE transport and reduced plasma membrane expression of NET and NK1R. Pretreatment with the NK1R antagonist, EMEND (aprepitant) prevented these NK1R-mediated effects. Immunoprecipitation experiments showed that NET forms stable complexes with NK1R. In HTR cells, combined biotinylation and immunoprecipitation studies revealed plasma membrane localization of NET·NK1R complexes. Receptor activation resulted in the internalization of NET·NK1R complexes. Lipid raft and immunoprecipitation analyses revealed the presence of NET·NK1R complexes exclusively in non-raft membrane fractions under basal/unstimulated conditions. However, NK1R activation led to translocation of NET·NK1R complexes to raft-rich membrane fractions. Importantly, PKCα was found in association with raft-localized NET following SP treatment. Similar to WT-NET, PKC-resistant NET-DM was found in association with NK1R exclusively in non-raft fractions. However, SP treatment failed to translocate NET-DM·NK1R complexes from non-raft fractions to raft fractions. Collectively, these results suggest that NK1R forms physical complexes with NET and that the receptor-mediated Thr(258) + Ser(259) motif-dependent translocation of NET·NK1R complexes into raft-rich microdomains facilitates NET/NK1R interaction with PKCα to coordinate spatially restricted NET regulation.
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Affiliation(s)
- Obulakshmi Arapulisamy
- From the Department of Neurosciences, Division of Neuroscience Research, Medical University of South Carolina, Charleston, South Carolina 29425 and
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Annamalai B, Mannangatti P, Arapulisamy O, Shippenberg TS, Jayanthi LD, Ramamoorthy S. Tyrosine phosphorylation of the human serotonin transporter: a role in the transporter stability and function. Mol Pharmacol 2012; 81:73-85. [PMID: 21992875 PMCID: PMC3250108 DOI: 10.1124/mol.111.073171] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Accepted: 10/12/2011] [Indexed: 11/22/2022] Open
Abstract
The serotonin (5-HT) transporter (SERT) regulates serotoninergic neurotransmission by clearing 5-HT released into the synaptic space. Phosphorylation of SERT on serine and threonine mediates SERT regulation. Whether tyrosine phosphorylation regulates SERT is unknown. Here, we tested the hypothesis that tyrosine-phosphorylation of SERT regulates 5-HT transport. In support of this, alkali-resistant (32)P-labeled SERT was found in rat platelets, and Src-tyrosine kinase inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo [3,4,d]pyrimidine (PP2) decreased platelet SERT function and expression. In human placental trophoblast cells expressing SERT, PP2 reduced transporter function, expression, and stability. Although siRNA silencing of Src expression decreased SERT function and expression, coexpression of Src resulted in PP2-sensitive increases in SERT function and expression. PP2 treatment markedly decreased SERT protein stability. Compared with WT-SERT, SERT tyrosine mutants Y47F and Y142F exhibited reduced 5-HT transport despite their higher total and cell surface expression levels. Moreover, Src-coexpression increased total and cell surface expression of Y47F and Y142F SERT mutants without affecting their 5-HT transport capacity. It is noteworthy that Y47F and Y142F mutants exhibited higher protein stability compared with WT-SERT. However, similar to WT-SERT, PP2 treatment decreased the stability of Y47F and Y142F mutants. Furthermore, compared with WT-SERT, Y47F and Y142F mutants exhibited lower basal tyrosine phosphorylation and no further enhancement of tyrosine phosphorylation in response to Src coexpression. These results provide the first evidence that SERT tyrosine phosphorylation supports transporter protein stability and 5HT transport.
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Affiliation(s)
- Balasubramaniam Annamalai
- Department of Neurosciences, Division of Neuroscience Research, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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Ramamoorthy S, Shippenberg TS, Jayanthi LD. Regulation of monoamine transporters: Role of transporter phosphorylation. Pharmacol Ther 2011; 129:220-38. [PMID: 20951731 PMCID: PMC3031138 DOI: 10.1016/j.pharmthera.2010.09.009] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 09/24/2010] [Indexed: 10/18/2022]
Abstract
Presynaptic biogenic amine transporters mediate reuptake of released amines from the synapse, thus regulating serotonin, dopamine and norepinephrine neurotransmission. Medications utilized in the treatment of depression, attention deficit-hyperactivity disorder and other psychiatric disorders possess high affinity for amine transporters. In addition, amine transporters are targets for psychostimulants. Altered expression of biogenic amine transporters has long been implicated in several psychiatric and degenerative disorders. Therefore, appropriate regulation and maintenance of biogenic amine transporter activity is critical for the maintenance of normal amine homoeostasis. Accumulating evidence suggests that cellular protein kinases and phosphatases regulate amine transporter expression, activity, trafficking and degradation. Amine transporters are phosphoproteins that undergo dynamic control under the influence of various kinase and phosphatase activities. This review presents a brief overview of the role of amine transporter phosphorylation in the regulation of amine transport in the normal and diseased brain. Understanding the molecular mechanisms by which phosphorylation events affect amine transporter activity is essential for understanding the contribution of transporter phosphorylation to the regulation of monoamine neurotransmission and for identifying potential new targets for the treatment of various brain diseases.
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Affiliation(s)
- Sammanda Ramamoorthy
- Department of Neurosciences, Division of Neuroscience Research, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Toni S. Shippenberg
- Integrative Neuroscience Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, U.S. Department of Health and Human Services, Baltimore MD 21224, USA
| | - Lankupalle D. Jayanthi
- Department of Neurosciences, Division of Neuroscience Research, Medical University of South Carolina, Charleston, South Carolina 29425
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