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Liu Chung Ming C, Wang X, Gentile C. Protective role of acetylcholine and the cholinergic system in the injured heart. iScience 2024; 27:110726. [PMID: 39280620 PMCID: PMC11402255 DOI: 10.1016/j.isci.2024.110726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/18/2024] Open
Abstract
This review explores the roles of the cholinergic system in the heart, comprising the neuronal and non-neuronal cholinergic systems. Both systems are essential for maintaining cardiac homeostasis by regulating the release of acetylcholine (ACh). A reduction in ACh release is associated with the early onset of cardiovascular diseases (CVDs), and increasing evidence supports the protective roles of ACh against CVD. We address the challenges and limitations of current strategies to elevate ACh levels, including vagus nerve stimulation and pharmacological interventions such as cholinesterase inhibitors. Additionally, we introduce alternative strategies to increase ACh in the heart, such as stem cell therapy, gene therapy, microRNAs, and nanoparticle drug delivery methods. These findings offer new insights into advanced treatments for regenerating the injured human heart.
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Affiliation(s)
- Clara Liu Chung Ming
- School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney, NSW, Australia
- Cardiovascular Regeneration Group, Heart Research Institute, Newtown, NSW 2042, Australia
| | - Xiaowei Wang
- Department of Medicine, Monash University, Melbourne, VIC 3800, Australia
- Department of Cardiometabolic Health, University of Melbourne, Melbourne, VIC 3010, Australia
- Molecular Imaging and Theranostics Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia
| | - Carmine Gentile
- School of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Sydney, NSW, Australia
- Cardiovascular Regeneration Group, Heart Research Institute, Newtown, NSW 2042, Australia
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2
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Qiu Y, Gao Y, Huang B, Bai Q, Zhao Y. Transport mechanism of presynaptic high-affinity choline uptake by CHT1. Nat Struct Mol Biol 2024; 31:701-709. [PMID: 38589607 DOI: 10.1038/s41594-024-01259-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 01/19/2024] [Indexed: 04/10/2024]
Abstract
Choline is a vital nutrient and a precursor for the biosynthesis of essential metabolites, including acetylcholine (ACh), that play a central role in fetal development, especially in the brain. In cholinergic neurons, the high-affinity choline transporter (CHT1) provides an extraordinarily efficient reuptake mechanism to reutilize choline derived from intrasynaptical ACh hydrolysis and maintain ACh synthesis in the presynapse. Here, we determined structures of human CHT1 in three discrete states: the outward-facing state bound with the competitive inhibitor hemicholinium-3 (HC-3); the inward-facing occluded state bound with the substrate choline; and the inward-facing apo open state. Our structures and functional characterizations elucidate how the inhibitor and substrate are recognized. Moreover, our findings shed light on conformational changes when transitioning from an outward-facing to an inward-facing state and establish a framework for understanding the transport cycle, which relies on the stabilization of the outward-facing state by a short intracellular helix, IH1.
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Affiliation(s)
- Yunlong Qiu
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yiwei Gao
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Bo Huang
- Beijing StoneWise Technology Co Ltd., Beijing, China
| | - Qinru Bai
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yan Zhao
- Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.
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3
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Developmental nicotine exposure impairs memory and reduces acetylcholine levels in the hippocampus of mice. Brain Res Bull 2021; 176:1-7. [PMID: 34358612 DOI: 10.1016/j.brainresbull.2021.07.030] [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: 04/18/2021] [Revised: 06/15/2021] [Accepted: 07/30/2021] [Indexed: 12/22/2022]
Abstract
Nicotine is a strong psychoactive and addictive compound found in tobacco. Use of nicotine in the form of smoking, vaping or other less common methods during pregnancy has been shown to be related to poor health conditions, including cognitive problems, in babies and children. However, mechanisms of such cognitive deficits are not fully understood. In this study we analyzed hippocampus dependent cognitive deficits using a mouse model of developmental nicotine exposure. Pregnant dams were exposed to nicotine and experiments were performed in one month old offspring. Our results show that nicotine exposure did not affect locomotor behavior in mice. Hippocampus dependent working memory and object location memory were diminished in nicotine exposed mice. Furthermore, acetylcholine levels in the hippocampus of nicotine exposed mice were reduced along with reduced activity of acetylcholinesterase enzyme. Analysis of transcripts for proteins that are known to regulate acetylcholine levels revealed a decline in mRNA levels of high affinity choline transporters in the hippocampus of nicotine exposed mice but those of vesicular acetylcholine transporter, choline acetyltransferase, and α7-nicotinic acetylcholine receptors were not altered. These results suggest that developmental nicotine exposure impairs hippocampus dependent memory forms and this effect is likely mediated by altered cholinergic function.
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4
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Díaz I, Colmenárez-Raga AC, Pérez-González D, Carmona VG, Plaza Lopez I, Merchán MA. Effects of Multisession Anodal Electrical Stimulation of the Auditory Cortex on Temporary Noise-Induced Hearing Loss in the Rat. Front Neurosci 2021; 15:642047. [PMID: 34393701 PMCID: PMC8358804 DOI: 10.3389/fnins.2021.642047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 04/30/2021] [Indexed: 11/13/2022] Open
Abstract
The protective effect of the efferent system against acoustic trauma (AT) has been shown by several experimental approaches, including damage to one ear, sectioning of the olivocochlear bundle (OCB) in the floor of the IV ventricle, and knock-in mice overexpressing outer hair cell (OHC) cholinergic receptors, among others. Such effects have been related to changes in the regulation of the cholinergic efferent system and in cochlear amplification, which ultimately reverse upon protective hearing suppression. In addition to well-known circuits of the brainstem, the descending corticofugal pathway also regulates efferent neurons of the olivary complex. In this study, we applied our recently developed experimental paradigm of multiple sessions of electrical stimulation (ES) to activate the efferent system in combination with noise overstimulation. ABR thresholds increased 1 and 2 days after AT (8-16 kHz bandpass noise at 107 dB for 90 min) recovering at AT + 14 days. However, after multiple sessions of epidural anodal stimulation, no changes in thresholds were observed following AT. Although an inflammatory response was also observed 1 day after AT in both groups, the counts of reactive macrophages in both experimental conditions suggest decreased inflammation in the epidural stimulation group. Quantitative immunocytochemistry for choline acetyltransferase (ChAT) showed a significant decrease in the size and optical density of the efferent terminals 1 day after AT and a rebound at 14 days, suggesting depletion of the terminals followed by a long-term compensatory response. Such a synthesis recovery was significantly higher upon cortical stimulation. No significant correlation was found between ChAT optical density and size of the buttons in sham controls (SC) and ES/AT + 1day animals; however, significant negative correlations were shown in all other experimental conditions. Therefore, our comparative analysis suggests that cochleotopic cholinergic neurotransmission is also better preserved after multisession epidural stimulation.
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Affiliation(s)
| | | | | | | | | | - Miguel A. Merchán
- Instituto de Neurociencias de Castilla y León (INCYL), Universidad de Salamanca, Salamanca, Spain
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Targeting organophosphorus compounds poisoning by novel quinuclidine-3 oximes: development of butyrylcholinesterase-based bioscavengers. Arch Toxicol 2020; 94:3157-3171. [PMID: 32583098 DOI: 10.1007/s00204-020-02811-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 06/15/2020] [Indexed: 01/04/2023]
Abstract
A library of 14 mono-oxime quinuclidinium-based compounds with alkyl or benzyl substituent were synthesized and characterized in vitro as potential antidotes for organophosphorus compounds (OP) poisoning treatment. We evaluated their potency for reversible inhibition and reactivation of OP inhibited human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and evaluated interactions by molecular docking studies. The reactivation was notable for both AChE and BChE inhibited by VX, cyclosarin, sarin and paraoxon, if quinuclidinium compounds contained the benzyl group attached to the quinuclidinium moiety. Out of all 14, oxime Q8 [4-bromobenzyl-3-(hydroxyimino)quinuclidinium bromide] was singled out as having the highest determined overall reactivation rate of approximately 20,000 M-1 min-1 for cyclosarin-inhibited BChE. Furthermore, this oxime in combination with BChE exhibited a capability to act as a bioscavenger of cyclosarin, degrading within 2 h up to 100-fold excess of cyclosarin concentration over the enzyme. Molecular modeling revealed that the position of the cyclohexyl moiety conjugated with the active site serine of BChE directs the favorable positioning of the quinuclidinium ring and the bromophenyl moiety of Q8, which makes phosphonylated-serine easily accessible for the nucleophilic displacement by the oxime group of Q8. This result presents a novel scaffold for the development of new BChE-based bioscavengers. Furthermore, a cytotoxic effect was not observed for Q8, which also makes it promising for further in vivo reactivation studies.
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Hamid R, Hajirnis N, Kushwaha S, Saleem S, Kumar V, Mishra RK. Drosophila Choline transporter non-canonically regulates pupal eclosion and NMJ integrity through a neuronal subset of mushroom body. Dev Biol 2019; 446:80-93. [DOI: 10.1016/j.ydbio.2018.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 11/25/2018] [Accepted: 12/07/2018] [Indexed: 12/19/2022]
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Saw EL, Kakinuma Y, Fronius M, Katare R. The non-neuronal cholinergic system in the heart: A comprehensive review. J Mol Cell Cardiol 2018; 125:129-139. [PMID: 30343172 DOI: 10.1016/j.yjmcc.2018.10.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 09/24/2018] [Accepted: 10/14/2018] [Indexed: 01/01/2023]
Abstract
The autonomic influences on the heart have a ying-yang nature, albeit oversimplified, the interplay between the sympathetic and parasympathetic system (known as the cholinergic system) is often complex and remain poorly understood. Recently, the heart has been recognized to consist of neuronal and non-neuronal cholinergic system (NNCS). The existence of cardiac NNCS has been confirmed by the presence of cholinergic markers in the cardiomyocytes, which are crucial for synthesis (choline acetyltransferase, ChAT), storage (vesicular acetylcholine transporter, VAChT), reuptake of choline for synthesis (high-affinity choline transporter, CHT1) and degradation (acetylcholinesterase, AChE) of acetylcholine (ACh). The non-neuronal ACh released from cardiomyocytes is believed to locally regulate some of the key physiological functions of the heart, such as regulation of heart rate, offsetting hypertrophic signals, maintenance of action potential propagation as well as modulation of cardiac energy metabolism via the muscarinic ACh receptor in an auto/paracrine manner. Apart from this, several studies have also provided evidence for the beneficial role of ACh released from cardiomyocytes against cardiovascular diseases such as sympathetic hyperactivity-induced cardiac remodeling and dysfunction as well as myocardial infarction, confirming the important role of NNCS in disease prevention. In this review, we aim to provide a fundamental overview of cardiac NNCS, and information about its physiological role, regulatory factors as well as its cardioprotective effects. Finally, we propose the different approaches to target cardiac NNCS as an adjunctive treatment to specifically address the withdrawal of neuronal cholinergic system in cardiovascular disease such as heart failure.
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Affiliation(s)
- Eng Leng Saw
- Department of Physiology-HeartOtago, School of Biomedical Sciences, University of Otago, New Zealand
| | - Yoshihiko Kakinuma
- Department of Physiology (Bioregulatory Science), Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Martin Fronius
- Department of Physiology-HeartOtago, School of Biomedical Sciences, University of Otago, New Zealand.
| | - Rajesh Katare
- Department of Physiology-HeartOtago, School of Biomedical Sciences, University of Otago, New Zealand.
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8
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Cuddy LK, Seah C, Pasternak SH, Rylett RJ. Amino-Terminal β-Amyloid Antibody Blocks β-Amyloid-Mediated Inhibition of the High-Affinity Choline Transporter CHT. Front Mol Neurosci 2017; 10:361. [PMID: 29163036 PMCID: PMC5681948 DOI: 10.3389/fnmol.2017.00361] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 10/19/2017] [Indexed: 11/13/2022] Open
Abstract
Alzheimer's disease (AD) is a common age-related neurodegenerative disorder that is characterized by progressive cognitive decline. The deficits in cognition and attentional processing that are observed clinically in AD are linked to impaired function of cholinergic neurons that release the neurotransmitter acetylcholine (ACh). The high-affinity choline transporter (CHT) is present at the presynaptic cholinergic nerve terminal and is responsible for the reuptake of choline produced by hydrolysis of ACh following its release. Disruption of CHT function leads to decreased choline uptake and ACh synthesis, leading to impaired cholinergic neurotransmission. We report here that cell-derived β-amyloid peptides (Aβ) decrease choline uptake activity and cell surface CHT protein levels in SH-SY5Y neural cells. Moreover, we make the novel observation that the amount of CHT protein localizing to early endosomes and lysosomes is decreased significantly in cells that have been treated with cell culture medium that contains Aβ peptides released from neural cells. The Aβ-mediated loss of CHT proteins from lysosomes is prevented by blocking lysosomal degradation of CHT with the lysosome inhibitor bafilomycin A1 (BafA1). BafA1 also attenuated the Aβ-mediated decrease in CHT cell surface expression. Interestingly, however, lysosome inhibition did not block the effect of Aβ on CHT activity. Importantly, neutralizing Aβ using an anti-Aβ antibody directed at the N-terminal amino acids 1-16 of Aβ, but not by an antibody directed at the mid-region amino acids 22-35 of Aβ, attenuates the effect of Aβ on CHT activity and trafficking. This indicates that a specific N-terminal Aβ epitope, or specific conformation of soluble Aβ, may impair CHT activity. Therefore, Aβ immunotherapy may be a more effective therapeutic strategy for slowing the progression of cognitive decline in AD than therapies designed to promote CHT cell surface levels.
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Affiliation(s)
- Leah K Cuddy
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada.,Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Claudia Seah
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada
| | - Stephen H Pasternak
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada.,Department of Clinical Neurological Sciences, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
| | - R Jane Rylett
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
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Chinthu R, Anju T, Paulose C. Cholinergic receptor alterations in the cerebral cortex of spinal cord injured rat. Biochem Biophys Rep 2017; 10:46-51. [PMID: 29114569 PMCID: PMC5637237 DOI: 10.1016/j.bbrep.2017.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 02/09/2017] [Accepted: 02/15/2017] [Indexed: 11/15/2022] Open
Abstract
Many areas of the cerebral cortex process sensory information or coordinate motor output necessary for control of movement. Disturbances in cortical cholinergic system can affect locomotor coordination. Spinal cord injury causes severe motor impairment and disturbances in cholinergic signalling can aggravate the situation. Considering the impact of cortical cholinergic firing in locomotion, we focussed the study in understanding the cholinergic alterations in cerebral cortex during spinal cord injury. The gene expression of key enzymes in cholinergic pathway - acetylcholine esterase and choline acetyl transferase showed significant upregulation in the cerebral cortex of spinal cord injured group compared to control with the fold increase in expression of acetylcholine esterase prominently higher than cholineacetyl transferase. The decreased muscarinic receptor density and reduced immunostaining of muscarinic receptor subtypes along with down regulated gene expression of muscarinic M1 and M3 receptor subtypes accounts for dysfunction of metabotropic acetylcholine receptors in spinal cord injury group. Ionotropic acetylcholine receptor alterations were evident from the decreased gene expression of alpha 7 nicotinic receptors and reduced immunostaining of alpha 7 nicotinic receptors in confocal imaging. Our data pin points the disturbances in cortical cholinergic function due to spinal cord injury; which can augment the locomotor deficits. This can be taken into account while devising a proper therapeutic approach to manage spinal cord injury.
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Affiliation(s)
| | - T.R. Anju
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin 682022, Kerala, India
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Lindner M, Bell T, Iqbal S, Mullins PG, Christakou A. In vivo functional neurochemistry of human cortical cholinergic function during visuospatial attention. PLoS One 2017; 12:e0171338. [PMID: 28192451 PMCID: PMC5305251 DOI: 10.1371/journal.pone.0171338] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 01/19/2017] [Indexed: 11/24/2022] Open
Abstract
Cortical acetylcholine is involved in key cognitive processes such as visuospatial attention. Dysfunction in the cholinergic system has been described in a number of neuropsychiatric disorders. Levels of brain acetylcholine can be pharmacologically manipulated, but it is not possible to directly measure it in vivo in humans. However, key parts of its biochemical cascade in neural tissue, such as choline, can be measured using magnetic resonance spectroscopy (MRS). There is evidence that levels of choline may be an indirect but proportional measure of acetylcholine availability in brain tissue. In this study, we measured relative choline levels in the parietal cortex using functional (event-related) MRS (fMRS) during performance of a visuospatial attention task, with a modelling approach verified using simulated data. We describe a task-driven interaction effect on choline concentration, specifically driven by contralateral attention shifts. Our results suggest that choline MRS has the potential to serve as a proxy of brain acetylcholine function in humans.
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Affiliation(s)
- Michael Lindner
- Centre for Integrative Neuroscience and Neurodynamics, and School of Psychology and Clinical Language Sciences, University of Reading, Reading, United Kingdom
| | - Tiffany Bell
- Centre for Integrative Neuroscience and Neurodynamics, and School of Psychology and Clinical Language Sciences, University of Reading, Reading, United Kingdom
| | - Somya Iqbal
- Centre for Integrative Neuroscience and Neurodynamics, and School of Psychology and Clinical Language Sciences, University of Reading, Reading, United Kingdom
| | | | - Anastasia Christakou
- Centre for Integrative Neuroscience and Neurodynamics, and School of Psychology and Clinical Language Sciences, University of Reading, Reading, United Kingdom
- * E-mail:
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11
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Ferreira-Vieira TH, Guimaraes IM, Silva FR, Ribeiro FM. Alzheimer's disease: Targeting the Cholinergic System. Curr Neuropharmacol 2016; 14:101-15. [PMID: 26813123 PMCID: PMC4787279 DOI: 10.2174/1570159x13666150716165726] [Citation(s) in RCA: 878] [Impact Index Per Article: 109.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 07/01/2015] [Accepted: 07/14/2015] [Indexed: 12/16/2022] Open
Abstract
Acetylcholine (ACh) has a crucial role in the peripheral and central nervous
systems. The enzyme choline acetyltransferase (ChAT) is responsible for
synthesizing ACh from acetyl-CoA and choline in the cytoplasm and the vesicular
acetylcholine transporter (VAChT) uptakes the neurotransmitter into synaptic
vesicles. Following depolarization, ACh undergoes exocytosis reaching the
synaptic cleft, where it can bind its receptors, including muscarinic and
nicotinic receptors. ACh present at the synaptic cleft is promptly hydrolyzed by
the enzyme acetylcholinesterase (AChE), forming acetate and choline, which is
recycled into the presynaptic nerve terminal by the high-affinity choline
transporter (CHT1). Cholinergic neurons located in the basal forebrain,
including the neurons that form the nucleus basalis of Meynert, are severely
lost in Alzheimer’s disease (AD). AD is the most ordinary cause of dementia
affecting 25 million people worldwide. The hallmarks of the disease are the
accumulation of neurofibrillary tangles and amyloid plaques. However, there is
no real correlation between levels of cortical plaques and AD-related cognitive
impairment. Nevertheless, synaptic loss is the principal correlate of disease
progression and loss of cholinergic neurons contributes to memory and attention
deficits. Thus, drugs that act on the cholinergic system represent a promising
option to treat AD patients.
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Affiliation(s)
| | | | | | - Fabiola M Ribeiro
- Departamento de Bioquimica e Imunologia, Instituto de Ciencias Biologicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
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12
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Dobrovinskaya O, Valencia-Cruz G, Castro-Sánchez L, Bonales-Alatorre EO, Liñan-Rico L, Pottosin I. Cholinergic Machinery as Relevant Target in Acute Lymphoblastic T Leukemia. Front Pharmacol 2016; 7:290. [PMID: 27630569 PMCID: PMC5005329 DOI: 10.3389/fphar.2016.00290] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 08/18/2016] [Indexed: 12/17/2022] Open
Abstract
Various types of non-neuronal cells, including tumors, are able to produce acetylcholine (ACh), which acts as an autocrine/paracrine growth factor. T lymphocytes represent a key component of the non-neuronal cholinergic system. T cells-derived ACh is involved in a stimulation of their activation and proliferation, and acts as a regulator of immune response. The aim of the present work was to summarize the data about components of cholinergic machinery in T lymphocytes, with an emphasis on the comparison of healthy and leukemic T cells. Cell lines derived from acute lymphoblastic leukemias of T lineage (T-ALL) were found to produce a considerably higher amount of ACh than healthy T lymphocytes. Additionally, ACh produced by T-ALL is not efficiently hydrolyzed, because acetylcholinesterase (AChE) activity is drastically decreased in these cells. Up-regulation of muscarinic ACh receptors was also demonstrated at expression and functional level, whereas nicotinic ACh receptors seem to play a less important role and not form functional channels in cells derived from T-ALL. We hypothesized that ACh over-produced in T-ALL may act as an autocrine growth factor and play an important role in leukemic clonal expansion through shaping of intracellular Ca2+ signals. We suggest that cholinergic machinery may be attractive targets for new drugs against T-ALL. Specifically, testing of high affinity antagonists of muscarinic ACh receptors as well as antagomiRs, which interfere with miRNAs involved in the suppression of AChE expression, may be the first choice options.
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Affiliation(s)
- Oxana Dobrovinskaya
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima Colima, México
| | - Georgina Valencia-Cruz
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima Colima, México
| | - Luis Castro-Sánchez
- Centro Universitario de Investigaciones Biomédicas, Universidad de ColimaColima, México; Consejo Nacional de Ciencia y TecnologíaMéxico City, México
| | | | - Liliana Liñan-Rico
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima Colima, México
| | - Igor Pottosin
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima Colima, México
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13
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Lips KS, Pfeil U, Reiners K, Rimasch C, Kuchelmeister K, Braun-Dullaeus RC, Haberberger RV, Schmidt R, Kummer W. Expression of the High-affinity Choline Transporter CHT1 in Rat and Human Arteries. J Histochem Cytochem 2016; 51:1645-54. [PMID: 14623932 DOI: 10.1177/002215540305101208] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The arterial vascular wall contains a non-neuronal intrinsic cholinergic system. The rate-limiting step in acetylcholine (ACh) synthesis is choline uptake. A high-affinity choline transporter, CHT1, has recently been cloned from neural tissue and has been identified in epithelial cholinergic cells. Here we investigated its presence in rat and human arteries and in primary cell cultures of rat vascular cells (endothelial cells, smooth muscle cells, fibroblasts). CHT1-mRNA was detected in the arterial wall and in all isolated cell types by RT-PCR using five different CHT1-specific primer pairs. Antisera raised against amino acids 29-40 of the rat sequence labeled a single band (50 kD) in Western blots of rat aorta, and an additional higher molecular weight band appeared in the hippocampus. Immunohistochemistry demonstrated CHT1 immunoreactivity in endothelial and smooth muscle cells in situ and in all cultured cell types. A high-affinity [3H]-choline uptake mechanism sharing characteristics with neuronal high-affinity choline uptake, i.e., sensitivity to hemicholinium-3 and dependence on sodium, was demonstrated in rat thoracic aortic segments by microimager autoradiography. Expression of the high-affinity choline transporter CHT1 is a novel component of the intrinsic non-neuronal cholinergic system of the arterial vascular wall, predominantly in the intimal and medial layers.
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Affiliation(s)
- Katrin S Lips
- Institute for Anatomy and Cell Biology, Justus-Liebig-University Giessen, Giessen, Germany.
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14
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Cuddy LK, Seah C, Pasternak SH, Rylett RJ. Differential regulation of the high-affinity choline transporter by wild-type and Swedish mutant amyloid precursor protein. J Neurochem 2015; 134:769-82. [DOI: 10.1111/jnc.13167] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 04/30/2015] [Accepted: 05/06/2015] [Indexed: 01/18/2023]
Affiliation(s)
- Leah K. Cuddy
- Molecular Medicine Research Group; Robarts Research Institute; London Ontario Canada
- Department of Physiology and Pharmacology; University of Western Ontario; London Ontario Canada
| | - Claudia Seah
- Molecular Medicine Research Group; Robarts Research Institute; London Ontario Canada
| | - Stephen H. Pasternak
- Molecular Medicine Research Group; Robarts Research Institute; London Ontario Canada
- Department of Physiology and Pharmacology; University of Western Ontario; London Ontario Canada
- Department of Clinical Neurological Sciences; Schulich School of Medicine & Dentistry; University of Western Ontario; London Ontario Canada
| | - Rebecca Jane Rylett
- Molecular Medicine Research Group; Robarts Research Institute; London Ontario Canada
- Department of Physiology and Pharmacology; University of Western Ontario; London Ontario Canada
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15
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Roy A, Guatimosim S, Prado VF, Gros R, Prado MAM. Cholinergic activity as a new target in diseases of the heart. Mol Med 2015; 20:527-37. [PMID: 25222914 DOI: 10.2119/molmed.2014.00125] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 09/09/2014] [Indexed: 12/21/2022] Open
Abstract
The autonomic nervous system is an important modulator of cardiac signaling in both health and disease. In fact, the significance of altered parasympathetic tone in cardiac disease has recently come to the forefront. Both neuronal and nonneuronal cholinergic signaling likely play a physiological role, since modulating acetylcholine (ACh) signaling from neurons or cardiomyocytes appears to have significant consequences in both health and disease. Notably, many of these effects are solely due to changes in cholinergic signaling, without altered sympathetic drive, which is known to have significant adverse effects in disease states. As such, it is likely that enhanced ACh-mediated signaling not only has direct positive effects on cardiomyocytes, but it also offsets the negative effects of hyperadrenergic tone. In this review, we discuss recent studies that implicate ACh as a major regulator of cardiac remodeling and provide support for the notion that enhancing cholinergic signaling in human patients with cardiac disease can reduce morbidity and mortality. These recent results support the idea of developing large clinical trials of strategies to increase cholinergic tone, either by stimulating the vagus or by increased availability of Ach, in heart failure.
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Affiliation(s)
- Ashbeel Roy
- Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada
| | - Silvia Guatimosim
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Vania F Prado
- Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada.,Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada
| | - Robert Gros
- Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada.,Department of Medicine, University of Western Ontario, London, Ontario, Canada
| | - Marco A M Prado
- Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada.,Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada
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16
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Zimmermann M. Neuronal AChE splice variants and their non-hydrolytic functions: redefining a target of AChE inhibitors? Br J Pharmacol 2014; 170:953-67. [PMID: 23991627 DOI: 10.1111/bph.12359] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 08/04/2013] [Accepted: 08/12/2013] [Indexed: 12/11/2022] Open
Abstract
AChE enzymatic inhibition is a core focus of pharmacological intervention in Alzheimer's disease (AD). Yet, AChE has also been ascribed non-hydrolytic functions, which seem related to its appearance in various isoforms. Neuronal AChE presents as a tailed form (AChE-T) predominantly found on the neuronal synapse, and a facultatively expressed readthough form (AChE-R), which exerts short to medium-term protective effects. Notably, this latter form is also found in the periphery. While these non-hydrolytic functions of AChE are most controversially discussed, there is evidence for them being additional targets of AChE inhibitors. This review aims to provide clarification as to the role of these AChE splice variants and their interplay with other cholinergic parameters and their being targets of AChE inhibition: AChE-R is particularly involved in the mediation of (anti-)apoptotic events in cholinergic cells, involving adaptation of various cholinergic parameters and a time-dependent link to the expression of neuroprotective factors. The AChE-T C-terminus is central to AChE activity regulation, while isolated AChE-T C-terminal fragments mediate toxic effects via the α7 nicotinic acetylcholine receptor. There is direct evidence for roles of AChE-T and AChE-R in neurodegeneration and neuroprotection, with these roles involving AChE as a key modulator of the cholinergic system: in vivo data further encourages the use of AChE inhibitors in the treatment of neurodegenerative conditions such as AD since effects on both enzymatic activity and the enzyme's non-hydrolytic functions can be postulated. It also suggests that novel AChE inhibitors should enhance protective AChE-R, while avoiding the concomitant up-regulation of AChE-T.
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Affiliation(s)
- M Zimmermann
- Department of Pharmacology, School of Pharmacy, Goethe University Frankfurt, Frankfurt am Main, Germany
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17
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Abstract
This article summarizes molecular properties of the high-affinity choline transporter (CHT1) with reference to the historical background focusing studies performed in laboratories of the author. CHT1 is present on the presynaptic terminal of cholinergic neurons, and takes up choline which is the precursor of acetylcholine. The Na(+)-dependent uptake of choline by CHT1 is the rate-limiting step for synthesis of acetylcholine. CHT1 is the integral membrane protein with 13 transmembrane segments, belongs to the Na(+)/glucose co-transporter family (SLC5), and has 20-25% homology with members of this family. A single nucleotide polymorphism (SNP) for human CHT1 has been identified, which has a replacement from isoleucine to valine in the third transmembrane segment and shows the choline uptake activity of 50-60% as much as that of wild-type CHT1. The proportion of this SNP is high among Asians. Possible importance of choline diet for those with this SNP was discussed.
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Affiliation(s)
- Tatsuya Haga
- Tokyo University, 7-3-1 Hongo, Tokyo 113-8654, Japan
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18
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Rae CD. A Guide to the Metabolic Pathways and Function of Metabolites Observed in Human Brain 1H Magnetic Resonance Spectra. Neurochem Res 2013; 39:1-36. [PMID: 24258018 DOI: 10.1007/s11064-013-1199-5] [Citation(s) in RCA: 327] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 11/08/2013] [Accepted: 11/11/2013] [Indexed: 12/20/2022]
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19
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Li G, Klein J, Zimmermann M. Pathophysiological amyloid concentrations induce sustained upregulation of readthrough acetylcholinesterase mediating anti-apoptotic effects. Neuroscience 2013; 240:349-60. [PMID: 23485809 DOI: 10.1016/j.neuroscience.2013.02.040] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 02/07/2013] [Accepted: 02/08/2013] [Indexed: 12/31/2022]
Abstract
Cholinergically differentiated SH-SY5Y neuroblastoma cells were treated with a pathophysiologically relevant, low (300 nM), and a high (3 μM) dose of amyloid beta 1-42 (Abeta) or 42-1 (revAbeta). At early (1 and 4h) and late (24h) time points, the pro- and anti-apoptotic factors--caspase-3 and p53, and B-cell lymphoma 2 protein (Bcl-2), respectively--were assessed together with lactate dehydrogenase (LDH) release as measure of cell viability and ATP levels as marker of mitochondrial activity. The low peptide dose significantly increased Bcl-2 and, time-delayed, caspase-3 and ATP levels, but barely impacted on LDH release, while the high concentration remarkably depressed Bcl-2 levels, depleted ATP and led to increased LDH release. We also monitored acetylcholinesterase (AChE) enzymatic activity and splice variant levels (tailed and readthrough AChE; AChE-T and AChE-R), and assessed choline acetyltransferase (ChAT) and high-affinity choline uptake (HACU). The low Abeta concentration drastically upregulated AChE-R and increased both ChAT and HACU, while the high dose caused cholinergic toxicity. We believe this study offers the first insight into the highly concentration-dependent effects of Abeta on cholinergic dynamics. In particular, it highlights the rescuing role of AChE-R as being, together with mitochondrial activity, involved in cholinergic adaptation to low doses of Abeta.
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Affiliation(s)
- G Li
- Department of Pharmacology, School of Pharmacy, Biocentre N260, Max-von-Laue Straße 9, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
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20
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Romeo C, Raveendran AT, Sobha NM, Paulose CS. Cholinergic receptor alterations in the brain stem of spinal cord injured rats. Neurochem Res 2012. [PMID: 23184186 DOI: 10.1007/s11064-012-0931-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cholinergic receptors in upper motor neurons of brain stem control locomotion and coordination. Present study unravels cholinergic alterations in brain stem during spinal cord injury to understand signalling pathway changes which may be associated with spinal cord injury mediated motor deficits. We evaluated cholinergic function in brain stem by studying the expression of choline acetyl transferase and acetylcholine esterase. We quantified metabotropic muscarinic cholinergic receptors by receptor assays for total muscarinic, muscarinic M1 and M3 receptor subunits, gene expression studies using Real Time PCR and confocal imaging using FITC tagged secondary antibodies. The gene expression of ionotropic nicotinic cholinergic receptors and confocal imaging were also studied. The results from our study showed metabolic disturbance in cholinergic pathway as choline acetyl transferase is down regulated and acetylcholine esterase is up regulated in spinal cord injury group. The significant decrease in muscarinic receptors showed by decreased receptor number along with down regulated gene expression and confocal imaging accounts for dysfunction of metabotropic acetylcholine receptors in spinal cord injury group. Ionotropic acetylcholine receptor alterations were evident from the decreased gene expression of alpha 7 nicotinic acetylcholine receptors and confocal imaging. The motor coordination was analysed by Grid walk test which showed an increased foot slips in spinal cord injured rats. The significant reduction in brain stem cholinergic function might have intensified the motor dysfunction and locomotor disabilities.
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Affiliation(s)
- Chinthu Romeo
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Kochi 682 022, Kerala, India
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21
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Ruggiero A, Wright J, Ferguson SM, Lewis M, Emerson K, Iwamoto H, Ivy MT, Holmstrand EC, Ennis EA, Weaver CD, Blakely RD. Nonoisotopic assay for the presynaptic choline transporter reveals capacity for allosteric modulation of choline uptake. ACS Chem Neurosci 2012; 3:767-81. [PMID: 23077721 PMCID: PMC3474274 DOI: 10.1021/cn3000718] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Accepted: 07/09/2012] [Indexed: 11/29/2022] Open
Abstract
Current therapies to enhance CNS cholinergic function rely primarily on extracellular acetylcholinesterase (AChE) inhibition, a pharmacotherapeutic strategy that produces dose-limiting side effects. The Na(+)-dependent, high-affinity choline transporter (CHT) is an unexplored target for cholinergic medication development. Although functional at the plasma membrane, CHT at steady-state is localized to synaptic vesicles such that vesicular fusion can support a biosynthetic response to neuronal excitation. To identify allosteric potentiators of CHT activity, we mapped endocytic sequences in the C-terminus of human CHT, identifying transporter mutants that exhibit significantly increased transport function. A stable HEK-293 cell line was generated from one of these mutants (CHT LV-AA) and used to establish a high-throughput screen (HTS) compatible assay based on the electrogenic nature of the transporter. We established that the addition of choline to these cells, at concentrations appropriate for high-affinity choline transport at presynaptic terminals, generates a hemicholinium-3 (HC-3)-sensitive, membrane depolarization that can be used for the screening of CHT inhibitors and activators. Using this assay, we discovered that staurosporine increased CHT LV-AA choline uptake activity, an effect mediated by a decrease in choline K(M) with no change in V(max). As staurosporine did not change surface levels of CHT, nor inhibit HC-3 binding, we propose that its action is directly or indirectly allosteric in nature. Surprisingly, staurosporine reduced choline-induced membrane depolarization, suggesting that increased substrate coupling to ion gradients, arising at the expense of nonstoichiometric ion flow, accompanies a shift of CHT to a higher-affinity state. Our findings provide a new approach for the identification of CHT modulators that is compatible with high-throughput screening approaches and presents a novel model by which small molecules can enhance substrate flux through enhanced gradient coupling.
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Affiliation(s)
- Alicia
M. Ruggiero
- Center for Molecular
Neuroscience,
Department of Pharmacology, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232-8548, United
States
| | - Jane Wright
- Center for Molecular
Neuroscience,
Department of Pharmacology, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232-8548, United
States
| | - Shawn M. Ferguson
- Center for Molecular
Neuroscience,
Department of Pharmacology, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232-8548, United
States
| | - Michelle Lewis
- Vanderbilt Institute
of Chemical
Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-6304, United States
| | - Katie
S. Emerson
- Center for Molecular
Neuroscience,
Department of Pharmacology, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232-8548, United
States
| | - Hideki Iwamoto
- Center for Molecular
Neuroscience,
Department of Pharmacology, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232-8548, United
States
| | - Michael T. Ivy
- Department of Biological Sciences, Tennessee State University, Nashville, Tennessee 37209-1561,
United States
| | - Ericka C. Holmstrand
- Center for Molecular
Neuroscience,
Department of Pharmacology, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232-8548, United
States
| | - Elizabeth. A. Ennis
- Center for Molecular
Neuroscience,
Department of Pharmacology, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232-8548, United
States
| | - C. David Weaver
- Vanderbilt Institute
of Chemical
Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-6304, United States
- Department
of Pharmacology, Vanderbilt University School of Medicine, Nashville,
Tennessee 37232-6600, United States
| | - Randy D. Blakely
- Center for Molecular
Neuroscience,
Department of Pharmacology, Vanderbilt University School
of Medicine, Nashville, Tennessee 37232-8548, United
States
- Department of Psychiatry, Vanderbilt
University School of Medicine, Nashville,
Tennessee 37232-8548, United States
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22
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Gupta RC. Brain regional heterogeneity and toxicological mechanisms of organophosphates and carbamates. Toxicol Mech Methods 2012; 14:103-43. [PMID: 20021140 DOI: 10.1080/15376520490429175] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The brain is a well-organized, yet highly complex, organ in the mammalian system. Most investigators use the whole brain, instead of a selected brain region(s), for biochemical analytes as toxicological endpoints. As a result, the obtained data is often of limited value, since their significance is compromised due to a reduced effect, and the investigators often arrive at an erroneous conclusion(s). By now, a plethora of knowledge reveals the brain regional variability for various biochemical/neurochemical determinants. This review describes the importance of brain regional heterogeneity in relation to cholinergic and noncholinergic determinants with particular reference to organophosphate (OP) and carbamate pesticides and OP nerve agents.
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Affiliation(s)
- Ramesh C Gupta
- Murray State University, Breathitt Veterinary Center, Toxicology Department, Hopkinsville, Kentucky, USA
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23
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Yamada H, Imajoh-Ohmi S, Haga T. The high-affinity choline transporter CHT1 is regulated by the ubiquitin ligase Nedd4-2. ACTA ACUST UNITED AC 2012; 33:1-8. [PMID: 22361880 DOI: 10.2220/biomedres.33.1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The high-affinity choline transporter (CHT1), which is specifically expressed in cholinergic neurons, constitutes a rate-limiting step for acetylcholine synthesis. We have found that the exogenous ubiquitin ligase Nedd4-2 interacts with CHT1 expressed in HEK293 cells decreasing the amount of cell surface CHT1 by approximately 40%, and that small interfering RNA for endogenous Nedd4-2 enhances the choline uptake activity by CHT1 in HEK293 cells. These results indicate that Nedd4-2-mediated ubiquitination regulates the cell surface expression of CHT1 in cultured cells and suggest a possibility that treatments or drugs which inhibit the interaction between CHT1 and Nedd4-2 might be useful for diseases involving decrease in acetylcholine level such as Alzheimer's disease.
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Affiliation(s)
- Haruhiko Yamada
- Department of Life Science, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan
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24
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Abstract
Cholinergic neurons are endowed with a high-affinity choline uptake system for efficient synthesis of acetylcholine at the presynaptic terminals. The high-affinity choline transporter CHT1 is responsible for choline uptake, the rate-limiting step in acetylcholine synthesis. However, endogenous physiological factors that affect CHT1 expression or function and consequently regulate the acetylcholine synthesis rate are essentially unknown. Here we demonstrate that extracellular substrate decreases the cell-surface expression of CHT1 in rat brain synaptosomes, primary cultures from the basal forebrain, and mammalian cell lines transfected with CHT1. Extracellular choline rapidly decreases cell-surface CHT1 expression by accelerating its internalization, a process that is mediated by a dynamin-dependent endocytosis pathway in HEK293 cells. Specific inhibitor hemicholinium-3 decreases the constitutive internalization rate and thereby increases cell-surface CHT1 expression. We also demonstrate that the constitutive internalization of CHT1 depends on extracellular pH in cultured cells. Our results collectively suggest that the internalization of CHT1 is induced by extracellular substrate, providing a novel feedback mechanism for the regulation of acetylcholine synthesis at the cholinergic presynaptic terminals.
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25
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Batra V, Kislay B, Devasagayam TPA. Interaction between total body gamma-irradiation and choline deficiency triggers immediate modulation of choline and choline-containing moieties. Int J Radiat Biol 2011; 87:1196-207. [PMID: 21923302 DOI: 10.3109/09553002.2011.624153] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE The objective of this study was to examine the effect of 60Co-gamma (γ) radiation on acute phase modulation, if any, of choline and choline-containing moieties in choline-deficient subjects. Corresponding results could provide information that might be useful in the management of adverse effects of γ-radiation. MATERIALS AND METHODS Male Swiss mice maintained on a choline-sufficient diet (CSD) and choline-free diet (CFD) based on AIN-93M formula, were subjected to whole body γ-irradiation (2-6 Gy). Liver, serum and brain samples from each group were then tested for: (i) Alterations in choline and choline-containing moieties such as phosphatidylcholine (PC) and sphingomyeline (SM); and (ii) modulation of choline profile modulating enzymes such as phospholipase D (PLD) and total sphingomyelinase (t-SMase). Liver and brain samples were also subjected to histo-pathological examinations. RESULTS No significant changes were observed in folate, choline, choline-containing moieties and choline-modulating enzymes in choline-sufficient mice. In contrast, interaction between cytotoxic effects of γ-radiation and choline deficiency modulated choline and choline-containing moieties. Feeding CFD reduced hepatic concentrations of choline, PC and SM whereas PLD and t-SMase activities were significantly raised. The decrease in liver choline and choline-containing moieties was accompanied by an increase in blood choline concentration. Despite choline deficiency, the level of choline and acetylcholine synthesizing enzyme choline acetyltransfease (ChAT) significantly increased in the brain. CONCLUSIONS We propose that choline deprivation and γ-radiation interact to modulate choline reserves of hepatic tissue, which might release choline to blood. Our studies also clearly showed that interaction between choline deficiency and γ-radiation might substantially enhance liver adipogenesis.
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Affiliation(s)
- Vipen Batra
- Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, India.
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26
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Matsuo A, Bellier JP, Nishimura M, Yasuhara O, Saito N, Kimura H. Nuclear choline acetyltransferase activates transcription of a high-affinity choline transporter. J Biol Chem 2010; 286:5836-45. [PMID: 21163949 DOI: 10.1074/jbc.m110.147611] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Choline acetyltransferase (ChAT) synthesizes the neurotransmitter, acetylcholine, at cholinergic nerve terminals. ChAT contains nuclear localization signals and is also localized in the nuclei of neural and non-neuronal cells. Nuclear ChAT might have an as yet unidentified function, such as transcriptional regulation. In this study, we investigated the alteration of candidate gene transcription by ChAT. We chose high affinity choline transporter (CHT1) and vesicular acetylcholine transporter (VACHT) as candidate genes, which function together with ChAT in acetylcholine production. Using SH-SY5Y human neuroblastoma cells stably expressing wild-type human ChAT, we found that overexpressed ChAT enhanced transcription of the CHT1 gene but not the VACHT gene. In contrast, nuclear localization signal disrupted, and catalytically inactive mutant ChATs could not induce, CHT1 expression. Additionally, ChAT did not alter CHT1 expression in non-neuronal HEK293 cells. Our results suggest that ChAT activates the transcription of selected target genes in neuronal cells. Both enzymatic activity and nuclear translocation of ChAT are required for its transcriptional enhancement.
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Affiliation(s)
- Akinori Matsuo
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga 520-2192, Japan.
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27
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English BA, Appalsamy M, Diedrich A, Ruggiero AM, Lund D, Wright J, Keller NR, Louderback KM, Robertson D, Blakely RD. Tachycardia, reduced vagal capacity, and age-dependent ventricular dysfunction arising from diminished expression of the presynaptic choline transporter. Am J Physiol Heart Circ Physiol 2010; 299:H799-810. [PMID: 20601463 DOI: 10.1152/ajpheart.00170.2010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Healthy cardiovascular function relies on a balanced and responsive integration of noradrenergic and cholinergic innervation of the heart. High-affinity choline uptake by cholinergic terminals is pivotal for efficient ACh production and release. To date, the cardiovascular impact of diminished choline transporter (CHT) expression has not been directly examined, largely due to the transporter's inaccessibility in vivo. Here, we describe findings from cardiovascular experiments using transgenic mice that bear a CHT genetic deficiency. Whereas CHT knockout (CHT(-/-)) mice exhibit early postnatal lethality, CHT heterozygous (CHT(+/-)) mice survive, grow, and reproduce normally and exhibit normal spontaneous behaviors. However, the CHT(+/-) mouse heart displays significantly reduced levels of high-affinity choline uptake accompanied by significantly reduced levels of ACh. Telemeterized recordings of cardiovascular function in these mice revealed tachycardia and hypertension at rest. After treadmill exercise, CHT(+/-) mice exhibited slower heart rate recovery, consistent with a diminished cholinergic reserve, a contention validated through direct vagal nerve stimulation. Echocardiographic and histological experiments revealed an age-dependent decrease in fractional shortening, increased left ventricular dimensions, and increased ventricular fibrosis, consistent with ventricular dysfunction. These cardiovascular phenotypes of CHT(+/-) mice encourage an evaluation of humans bearing reduced CHT expression for their resiliency in maintaining proper heart function as well as risk for cardiovascular disease.
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Affiliation(s)
- Brett A English
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-8548, USA
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28
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Regulation of cortical acetylcholine release: insights from in vivo microdialysis studies. Behav Brain Res 2010; 221:527-36. [PMID: 20170686 DOI: 10.1016/j.bbr.2010.02.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Accepted: 02/10/2010] [Indexed: 01/12/2023]
Abstract
Acetylcholine release links the activity of presynaptic neurons with their postsynaptic targets and thus represents the intercellular correlate of cholinergic neurotransmission. Here, we review the regulation and functional significance of acetylcholine release in the mammalian cerebral cortex, with a particular emphasis on information derived from in vivo microdialysis studies over the past three decades. This information is integrated with anatomical and behavioral data to derive conclusions regarding the role of cortical cholinergic transmission in normal behavioral and how its dysregulation may contribute to cognitive correlates of several neuropsychiatric conditions. Some unresolved issues regarding the regulation and significance of cortical acetylcholine release and the promise of new methodology for advancing our knowledge in this area are also briefly discussed.
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29
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Fujii T, Masai M, Misawa H, Okuda T, Takada-Takatori Y, Moriwaki Y, Haga T, Kawashima K. Acetylcholine synthesis and release in NIH3T3 cells coexpressing the high-affinity choline transporter and choline acetyltransferase. J Neurosci Res 2010; 87:3024-32. [PMID: 19405101 DOI: 10.1002/jnr.22117] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Acetylcholine (ACh) is known to be a key neurotransmitter in the central and peripheral nervous systems, but it is also produced in a variety of non-neuronal tissues and cells, including lymphocytes, placenta, amniotic membrane, vascular endothelial cells, keratinocytes, and epithelial cells in the digestive and respiratory tracts. To investigate contribution made by the high-affinity choline transporter (CHT1) to ACh synthesis in both cholinergic neurons and nonneuronal cells, we transfected rat CHT1 cDNA into NIH3T3ChAT cells, a mouse fibroblast line expressing mouse choline acetyltransferase (ChAT), to establish the NIH3T3ChAT 112-1 cell line, which stably expresses both CHT1 and ChAT. NIH3T3ChAT 112-1 cells showed increased binding of the CHT1 inhibitor [(3)H]hemicholinium-3 (HC-3) and greater [(3)H]choline uptake and ACh synthesis than NIH3T3ChAT 103-1 cells, a CHT1-negative control cell line. HC-3 significantly inhibited ACh synthesis in NIH3T3ChAT 112-1 cells but did not affect synthesis in NIH3T3ChAT 103-1 cells. ACh synthesis in NIH3T3ChAT 112-1 cells was also reduced by amiloride, an inhibitor of organic cation transporters (OCTs) involved in low-affinity choline uptake, and by procaine and lidocaine, two local anesthetics that inhibit plasma membrane phospholipid metabolism. These results suggest that CHT1 plays a key role in ACh synthesis in NIH3T3ChAT 112-1 cells and that choline taken up by OCTs or derived from the plasma membrane is also utilized for ACh synthesis in both cholinergic neurons and nonneuronal cholinergic cells, such as lymphocytes.
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Affiliation(s)
- Takeshi Fujii
- Department of Pharmacology, Faculty of Pharmacy, Keio University, Tokyo, Japan. tfujii-dwc.doshisha.ac.jp
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30
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Cooke JP, Ghebremariam YT. Endothelial nicotinic acetylcholine receptors and angiogenesis. Trends Cardiovasc Med 2009; 18:247-53. [PMID: 19232953 DOI: 10.1016/j.tcm.2008.11.007] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Revised: 11/18/2008] [Accepted: 11/20/2008] [Indexed: 10/21/2022]
Abstract
Nicotinic acetylcholine receptors (nAChRs) were first described in non-excitable cells just more than a decade ago. The nAChRs on endothelial cells modulate key angiogenic processes, including endothelial cell survival, proliferation, and migration. The receptors may be stimulated by endogenous agonists such as acetylcholine, or exogenous chemicals such as nicotine, to activate physiologic angiogenesis (such as in wound healing) or pathologic angiogenesis (such as retinal neovascularization or tumor angiogenesis). The endothelial nAChRs may represent a target for therapeutic modulation of disorders characterized by insufficient or pathologic angiogenesis.
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Affiliation(s)
- John P Cooke
- Division of Cardiovascular Medicine, Stanford University, Stanford, CA 94305, USA.
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31
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Wang M, Wen H, Brehm P. Function of neuromuscular synapses in the zebrafish choline-acetyltransferase mutant bajan. J Neurophysiol 2008; 100:1995-2004. [PMID: 18684905 DOI: 10.1152/jn.90517.2008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have identified a zebrafish mutant line, bajan, in which compromised motility and fatigue result from a point mutation in the gene coding choline acetyltransferase (ChAT), the enzyme responsible for acetylcholine (ACh) synthesis. Although the mutation predicts loss of ChAT function, bajan inexplicably retains low levels of neuromuscular transmission. We exploited this residual activity and determined the consequences for synaptic function. The attenuated synaptic responses were a direct consequence of a decrease in both resting mean quantal size and quantal content. To replicate behavioral fatigue in swimming, motorneurons were stimulated at high frequencies. A prominent reduction in quantal content, reflecting vesicle depletion, was coincident with a small additional reduction in quantal size. In humans, defective ChAT leads to episodic apnea, a form of congenital myasthenic syndrome characterized by use-dependent fatigue. In contrast to bajan, however, afflicted individuals exhibit a normal resting quantal size and quantal content. The fatigue in humans results from a pronounced long-lasting drop in quantal size with little or no change in quantal content. These differences have important implications for interpreting fatigue as well as on understanding the impact of ACh availability on vesicle filling and recycling.
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Affiliation(s)
- Meng Wang
- Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, USA
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Bennett KM, Hoelting C, Martin CP, Stoll J. Estrogen effects on high-affinity choline uptake in primary cultures of rat basal forebrain. Neurochem Res 2008; 34:205-14. [PMID: 18483854 DOI: 10.1007/s11064-008-9746-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Accepted: 05/07/2008] [Indexed: 10/22/2022]
Abstract
Basal forebrain cholinergic neurons (BFCNs) degenerate in aging and Alzheimer's disease. It has been proposed that estrogen can affect the survival and function of BFCNs. This study characterized primary rat BFCN cultures and investigated the effect of estrogen on high-affinity choline uptake (HACU). BFCNs were identified by immunoreactivity to the vesicular acetylcholine transporter (VAChT) and represented up to 5% of total cells. HACU was measured in living BFCN cultures and differentiated from low-affinity choline uptake by hemicholinium-3 (HC-3) inhibition. A HC-3 concentration curve showed that 0.3 muM HC-3, but not higher concentrations that inhibit LACU, could distinguish the two transport activities. 17-beta-Estradiol treatment increased HACU in some culture preparations that contained non-neuronal cells. Elimination of dividing cells using antimitotic treatments resulted in a lack of estrogen effects on HACU. These results suggest that estrogen may have indirect effects on BFCNs that are mediated through non-neuronal cells.
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Affiliation(s)
- Katie M Bennett
- Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, School of Pharmacy, 1300 S Coulter, Amarillo, TX 79106, USA
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MKC-231, a choline uptake enhancer: (3) mode of action of MKC-231 in the enhancement of high-affinity choline uptake. J Neural Transm (Vienna) 2008; 115:1037-46. [DOI: 10.1007/s00702-008-0049-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Accepted: 03/28/2008] [Indexed: 10/22/2022]
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Ribeiro FM, Pinthong M, Black SAG, Gordon AC, Prado VF, Prado MAM, Rylett RJ, Ferguson SSG. Regulated recycling and plasma membrane recruitment of the high-affinity choline transporter. Eur J Neurosci 2008; 26:3437-48. [PMID: 18088276 DOI: 10.1111/j.1460-9568.2007.05967.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The high-affinity choline transporter (CHT1) is responsible for uptake of choline from the synaptic cleft and supplying choline for acetylcholine synthesis. CHT1 internalization by clathrin-coated vesicles is proposed to represent a mechanism by which high-affinity choline uptake can be modulated. We show here that internalized CHT1 is rapidly recycled back to the cell surface in both human embryonic kidney cells (HEK 293 cells) and SH-SY5Y neuroblastoma cells. This rapidly recycling pool of CHT1 comprises about 10% of total CHT1 protein. In the SH-SY5Y neuroblastoma cell line K(+)-depolarization promotes Ca(2+)-dependent increase in the rate of CHT1 recycling to the plasma membrane without affecting the rate of CHT1 internalization. K(+)-depolarization also increases the size of the pool of CHT1 protein that can be mobilized to the plasma membrane. Thus, the activity-dependent increase in plasma membrane CHT1 localization appears to be regulated by two mechanisms: (i) an increase in the rate of externalization of the intracellular CHT1 pool; and (ii) the recruitment of additional intracellular transporters to the recycling pool.
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Affiliation(s)
- Fabiola M Ribeiro
- Cell Biology Research Group, Robarts Research Institute London, Ontario, Canada
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35
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Mao C, Yuan X, Zhang H, Lv J, Guan J, Miao L, Chen L, Zhang Y, Zhang L, Xu Z. The effect of prenatal nicotine on mRNA of central cholinergic markers and hematological parameters in rat fetuses. Int J Dev Neurosci 2008; 26:467-75. [PMID: 18407449 DOI: 10.1016/j.ijdevneu.2008.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2007] [Revised: 02/24/2008] [Accepted: 02/25/2008] [Indexed: 11/28/2022] Open
Abstract
A number of studies have demonstrated the influence of nicotine on fetal development. This study determined the expression of choline acetyltransferase (ChAT), vesicular acetylcholine transporter (VAChT), and high-affinity choline transporter (CHT1) in the forebrain and hindbrain following chronic prenatal nicotine exposure in the rat fetus (maternal rats were subcutaneously injected with nicotine at different gestation periods). We also measured the effect of chronic nicotine exposure on fetal blood pO(2), pCO(2), pH, Na(+) and K(+) concentrations, as well as lactic acid levels. Maternal nicotine exposure during pregnancy was associated with a decrease in fetal pO(2) coupled with a significant increase in pCO(2) and lactic acid as well as restricted fetal growth. Additionally, maternal nicotine administration also reduced ChAT, VAChT, and CHT1 mRNA levels in the fetal brain. Nicotine-induced fetal hypoxic responses and reduced cholinergic marker expression in the brain were more severe when nicotine was started in early gestation. Our results provide new information about the effects of repeated exposure to nicotine in utero on the expression of central ChAT, VAChT, and CHT1 in the rat fetus. These results indicate that repeated hypoxic episodes or/and a direct effect of nicotine on the central cholinergic system during pregnancy may contribute to brain developmental problems in fetal origin.
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Affiliation(s)
- Caiping Mao
- Perinatal Biology Center, Soochow University School of Medicine, Suzhou, China
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36
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Choline availability and acetylcholine synthesis in the hippocampus of acetylcholinesterase-deficient mice. Neurochem Int 2007; 52:972-8. [PMID: 18023504 DOI: 10.1016/j.neuint.2007.10.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 10/08/2007] [Accepted: 10/10/2007] [Indexed: 11/21/2022]
Abstract
Mice deficient for acetylcholinesterase (AChE) have strongly increased extracellular levels of acetylcholine (ACh) in the dorsal hippocampus [Hartmann, J., Kiewert, C., Duysen, E.G., Lockridge, O., Greig, N.H., Klein, J., 2007. Excessive hippocampal acetylcholine levels in acetylcholinesterase-deficient mice are moderated by butyrylcholinesterase activity. J. Neurochem. 100, 1421-1429]. Using microdialysis, we found that increased ACh levels are accompanied by decreased levels of extracellular choline which were 1.60 microM in AChE-deficient mice and 4.36 microM in wild-type mice. Addition of choline (10 microM) to the perfusion fluid, while ineffective in wild-type animals, more than doubled extracellular ACh levels in AChE-deficient mice. High-affinity choline uptake (HACU), as measured ex vivo in corticohippocampal synaptosomes, was more than doubled in AChE-deficient mice. Inhibition of HACU by hemicholinium-3 (HC-3) in vivo reduced extracellular levels of ACh by 60% in wild-type mice but by more than 90% in AChE-deficient mice. Decreased ACh levels caused by infusion of HC-3 or tetrodotoxin (TTX) were accompanied by increased levels of free choline. Infusion of scopolamine (1 microM) caused a fivefold increase of ACh levels in wild-type animals but only a 50% increase in AChE-deficient mice. In conclusion, absence of AChE causes dynamic changes in the ratio of choline to ACh. High levels of extracellular ACh are accompanied by reduced levels of extracellular choline, and ACh release becomes strongly dependent on choline availability. Similar changes may take place in patients chronically exposed to AChE inhibitors.
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Silva VS, Nunes MA, Cordeiro JM, Calejo AI, Santos S, Neves P, Sykes A, Morgado F, Dunant Y, Gonçalves PP. Comparative effects of aluminum and ouabain on synaptosomal choline uptake, acetylcholine release and (Na+/K+)ATPase. Toxicology 2007; 236:158-77. [PMID: 17560001 DOI: 10.1016/j.tox.2007.04.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Revised: 03/16/2007] [Accepted: 04/10/2007] [Indexed: 11/25/2022]
Abstract
Closing the gap between adverse health effects of aluminum and its mechanisms of action still represents a huge challenge. Cholinergic dysfunction has been implicated in neuronal injury induced by aluminum. Previously reported data also indicate that in vivo and in vitro exposure to aluminum inhibits the mammalian (Na(+)/K(+))ATPase, an ubiquitous plasma membrane pump. This study was undertaken with the specific aim of determining whether in vitro exposure to AlCl(3) and ouabain, the foremost utilized selective inhibitor of (Na(+)/K(+))ATPase, induce similar functional modifications of cholinergic presynaptic nerve terminals, by comparing their effects on choline uptake, acetylcholine release and (Na(+)/K(+))ATPase activity, on subcellular fractions enriched in synaptic nerve endings isolated from rat brain, cuttlefish optic lobe and torpedo electric organ. Results obtained show that choline uptake by rat synaptosomes was inhibited by submillimolar AlCl(3), whereas the amount of choline taken up by synaptosomes isolated from cuttlefish and torpedo remained unchanged. Conversely, choline uptake was reduced by ouabain to a large extent in all synaptosomal preparations analyzed. In contrast to ouabain, which modified the K(+) depolarization evoked release of acetylcholine by rat, cuttlefish and torpedo synaptosomal fractions, AlCl(3) induced reduction of stimulated acetylcholine release was only observed when rat synaptosomes were challenged. Finally, it was observed that the aluminum effect on cuttlefish and torpedo synaptosomal (Na(+)/K(+))ATPase activity was slight when compared to its inhibitory action on mammalian (Na(+)/K(+))ATPase. In conclusion, inhibition of (Na(+)/K(+))ATPase by AlCl(3) and ouabain jeopardized the high-affinity (Na(+)-dependent, hemicholinium-3 sensitive) uptake of choline and the Ca(2+)-dependent, K(+) depolarization evoked release of acetylcholine by rat, cuttlefish and torpedo synaptosomal fractions. The effects of submillimolar AlCl(3) on choline uptake and acetylcholine release only resembled those of ouabain when rat synaptosomes were assayed. Therefore, important differences were found between the species regarding the cholinotoxic action of aluminum. The variability of (Na(+)/K(+))ATPase sensitivity to aluminum of cholinergic neurons might contribute to their differential susceptibility to this neurotoxic agent.
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Affiliation(s)
- Virgília S Silva
- CESAM, Departamento de Biologia, Universidade de Aveiro, 3810-193 Aveiro, Portugal
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38
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Iwamoto H, Blakely RD, De Felice LJ. Na+, Cl-, and pH dependence of the human choline transporter (hCHT) in Xenopus oocytes: the proton inactivation hypothesis of hCHT in synaptic vesicles. J Neurosci 2006; 26:9851-9. [PMID: 17005849 PMCID: PMC6674471 DOI: 10.1523/jneurosci.1862-06.2006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The recent cloning of the human choline transporter (hCHT) has allowed its expression in Xenopus laevis oocytes and the simultaneous measurement of choline transport and choline-induced current under voltage clamp. hCHT currents and choline transport are evident in cRNA-injected oocytes and significantly enhanced by the hCHT trafficking mutant L530A/V531A. The charge/choline ratio of hCHT varies from 10e/choline at -80 mV to 3e/choline at -20 mV, in contrast with the reported fixed stoichiometry of the Na+-coupled glucose transporter in the same gene family. Ion substitution shows that the choline uptake and choline-induced current are Na+ and Cl- dependent; however, the reversal potential of the induced current suggests a Na+-selective mechanism, consigning Cl- to a regulatory role rather than a coupled, cotransported-ion role. The hCHT-specific inhibitor hemicholinium-3 (HC-3) blocks choline uptake and choline-induced current; in addition, HC-3 alone reveals a constitutive, depolarizing leak current through hCHT. We show that external protons reduce hCHT current, transport, and binding with a similar pKa of 7.4, suggesting proton titration of residue(s) that support choline binding and transport. Given the localization of the choline transporter to synaptic vesicles, we propose that proton inactivation of hCHT prevents acetylcholine and proton leakage from the acidic interior of cholinergic synaptic vesicles. This mechanism would allow cholinergic, activity-triggered delivery of silent choline transporters to the plasma membrane, in which normal pH would reactivate the transporters for choline uptake and subsequent acetylcholine synthesis.
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Affiliation(s)
- Hideki Iwamoto
- Department of Pharmacology and Center for Molecular Neuroscience, Vanderbilt University School of Medicine, Nashville Tennessee 37232-8548
| | - Randy D. Blakely
- Department of Pharmacology and Center for Molecular Neuroscience, Vanderbilt University School of Medicine, Nashville Tennessee 37232-8548
| | - Louis J. De Felice
- Department of Pharmacology and Center for Molecular Neuroscience, Vanderbilt University School of Medicine, Nashville Tennessee 37232-8548
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Bazalakova MH, Blakely RD. The high-affinity choline transporter: a critical protein for sustaining cholinergic signaling as revealed in studies of genetically altered mice. Handb Exp Pharmacol 2006:525-44. [PMID: 16722248 DOI: 10.1007/3-540-29784-7_21] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In cholinergic neurons, the presynaptic choline transporter (CHT) mediates high-affinity choline uptake (HACU) as the rate-limiting step in acetylcholine (ACh) synthesis. It has previously been shown that HACU is increased by behaviorally and pharmacologically-induced activity of cholinergic neurons in vivo, but the molecular mechanisms of this change in CHT function and regulation have only recently begun to be elucidated. The recent cloning of CHT has led to the generation of new valuable tools, including specific anti-CHT antibodies and a CHT knockout mouse. These new reagents have allowed researchers to investigate the possibility of a presynaptic, CHT-mediated, molecular plasticity mechanism, regulated by and necessary for sustained in vivo cholinergic activity. Studies in various mouse models of cholinergic dysfunction, including acetylcholinesterase (AChE) transgenic and knockout mice, choline acetyltransferase (ChAT) heterozygote mice, muscarinic (mAChR) and nicotinic (mAChR) receptor knockout mice, as well as CHT knockout and heterozygote mice, have revealed new information about the role of CHT expression and regulation in response to long-term alterations in cholinergic neurotransmission. These mouse models highlight the capacity of CHT to provide for functional compensation in states of cholinergic dysfunction. A better understanding of modes of CHT regulation should allow for experimental manipulation of cholinergic signaling in vivo with potential utility in human disorders of known cholinergic dysfunction such as Alzheimer's disease, Parkinson's disease, schizophrenia, Huntington's disease, and dysautonomia.
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Affiliation(s)
- M H Bazalakova
- Vanderbilt School of Medicine, Suite 7140, MRB III, Nashville, TN 37232-8548, USA
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40
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Guseva M, Hopkins D, Pauly J. An autoradiographic analysis of rat brain nicotinic receptor plasticity following dietary choline modification. Pharmacol Biochem Behav 2006; 84:26-34. [PMID: 16753203 PMCID: PMC1976431 DOI: 10.1016/j.pbb.2006.04.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Revised: 04/04/2006] [Accepted: 04/19/2006] [Indexed: 11/18/2022]
Abstract
Choline is known to be involved with numerous physiological functions of the nervous system and also acts as a direct acting agonist of alpha7 nicotinic acetylcholine receptors (nAChRs). The purpose of this study was to conduct a brain region-specific evaluation of changes in nAChR subtype expression following dietary choline modification. In addition, we assessed changes in body weight, food/water intake, as well as changes in spatial learning (Morris Water Maze) in response to dietary choline modification. Male Sprague-Dawley rats were exposed to standard, choline supplemented or choline deficient diets for periods of 14 or 28 days. Choline supplemented animals gained significantly less weight over the course of the experiment, in spite of the fact that there were minimal differences in food consumption between the dietary regimens. Spatial memory did not differ between animals maintained on a standard rat diet, and the choline supplemented food. Brains of the animals kept on the diets for 14 and 28 days were used for quantitative autoradiographic analysis of nicotinic receptor subtypes using 125I-Bungarotoxin (alpha7) and 125I-Epibatidine (non-alpha7). There were no significant differences in nicotinic receptor binding or physiologic parameters measured between animals fed standard and choline deficient diets. However 2 weeks of dietary choline supplementation caused significant up-regulation of alpha7 receptors without significant effect on the density of non-alpha7 nAChRs. Increases in BTX binding predominantly occurred in cortical and hippocampal brain regions and ranged between 14 and 30% depending on the brain region. The results of our study suggest that choline acts as a selective agonist at alpha7 nicotinic cholinergic receptors in the rat central nervous system.
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41
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Lockman PR, Gaasch J, McAfee G, Abbruscato TJ, Van der Schyf CJ, Allen DD. Nicotine Exposure Does not Alter Plasma to Brain Choline Transfer. Neurochem Res 2006; 31:503-8. [PMID: 16758358 DOI: 10.1007/s11064-006-9047-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/10/2006] [Indexed: 12/15/2022]
Abstract
Acute and chronic nicotine exposure in rats is associated with an increase in brain acetylcholine (ACh) transmission. The acquisition of choline for neuronal ACh synthesis occurs primarily via two pathways; first, free choline is transported from the blood across the blood-brain barrier (BBB) and/or second, from synaptic choline generated by either hydrolysis of non-bound ACh or membrane phosphatidylcholine catabolism. To determine if nicotine-induced cholinergic demand is associated with increased choline transport rates into brain, we measured BBB choline transport in naïve and S-(-) nicotine exposed rats (acute and chronic, 4.5 mg/kg/d for 1, 14, 21 and 28 d; osmotic minipumps) using the in situ rat brain perfusion technique. No significant changes in choline uptake after acute or chronic nicotine exposure were observed in whole brain or cortex. Of considerable interest was a significant decrease in regional brain choline uptake measured in the hippocampus after chronic nicotine exposure (28 d). Our data suggest that the increased ACh transmission observed after nicotine exposure does not correlate with increased blood-to-brain transfer of choline. Considering these data and previous literature reports, we propose that the additional free choline required under conditions of nicotine exposure (for ACh synthesis) is primarily recruited from membrane phospholipid metabolism.
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Affiliation(s)
- Paul R Lockman
- Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, Amarillo, 79106-1712, USA.
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42
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Bergeron AL, Schrader A, Yang D, Osman AA, Simmons DD. The final stage of cholinergic differentiation occurs below inner hair cells during development of the rodent cochlea. J Assoc Res Otolaryngol 2006; 6:401-15. [PMID: 16228856 PMCID: PMC2504619 DOI: 10.1007/s10162-005-0018-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2005] [Accepted: 08/31/2005] [Indexed: 11/25/2022] Open
Abstract
To gain further insights into the cholinergic differentiation of presynaptic efferent terminals in the inner ear, we investigated the expression of the high-affinity choline transporter (ChT1) in comparison to other presynaptic and cholinergic markers. In the adult mammalian cochlea, cholinergic axons from medial olivocochlear (OC) neurons form axosomatic synapses with outer hair cells (OHCs), whereas axons from lateral OC neurons form axodendritic synapses on afferent fibers below inner hair cells (IHCs). Mouse brain and cochlea homogenates reveal at least two ChT1 isoforms: a nonglycosylated approximately 73 kDa protein and a glycosylated approximately 45 kDa protein. In mouse brain, ChT1 is preferentially expressed by neurons in periolivary regions of the superior olive consistent with the location of medial OC neurons. In the adult mouse cochlea, ChT1-positive terminals are located almost exclusively below OHCs consistent with a medial OC innervation. Between postnatal day 2 (P2) and P4, ChT1-positive terminals are below IHCs and occur after the expression of growth-associated protein 43, synapsin, and the vesicular acetylcholine transporter. By P15, ChT1-positive terminals are mostly on OHCs. Accounting for differences in gestational age, the developmental expression of ChT1 in the rat cochlea is similar to the mouse. However, in older rats ChT1-positive terminals are below IHCs and OHCs. In both rat and mouse, our observations indicate that the onset of ChT1 expression occurs after efferent terminals are below IHCs and express other presynaptic and cholinergic markers. In the mouse, but not in the rat, ChT1 may preferentially identify medial OC neurons.
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Affiliation(s)
- Adam L. Bergeron
- Department of Otolaryngology, Washington University School of Medicine, Box 8115, 660 South Euclid Ave., St. Louis, MO 63110 USA
- Program in Neuroscience, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - Angela Schrader
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - Dan Yang
- Department of Otolaryngology, Washington University School of Medicine, Box 8115, 660 South Euclid Ave., St. Louis, MO 63110 USA
| | - Abdullah A. Osman
- Department of Otolaryngology, Washington University School of Medicine, Box 8115, 660 South Euclid Ave., St. Louis, MO 63110 USA
| | - Dwayne D. Simmons
- Department of Otolaryngology, Washington University School of Medicine, Box 8115, 660 South Euclid Ave., St. Louis, MO 63110 USA
- Program in Neuroscience, Washington University School of Medicine, St. Louis, MO 63110 USA
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110 USA
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43
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Ribeiro FM, Black SAG, Prado VF, Rylett RJ, Ferguson SSG, Prado MAM. The "ins" and "outs" of the high-affinity choline transporter CHT1. J Neurochem 2006; 97:1-12. [PMID: 16524384 DOI: 10.1111/j.1471-4159.2006.03695.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Maintenance of acetylcholine (ACh) synthesis depends on the activity of the high-affinity choline transporter (CHT1), which is responsible for the reuptake of choline from the synaptic cleft into presynaptic neurons. In this review, we discuss the current understanding of mechanisms involved in the cellular trafficking of CHT1. CHT1 protein is mainly found in intracellular organelles, such as endosomal compartments and synaptic vesicles. The presence of CHT1 at the plasma membrane is limited by rapid endocytosis of the transporter in clathrin-coated pits in a mechanism dependent on a dileucine-like motif present in the carboxyl-terminal region of the transporter. The intracellular pool of CHT1 appears to constitute a reserve pool of transporters, important for maintenance of cholinergic neurotransmission. However, the physiological basis of the presence of CHT1 in intracellular organelles is not fully understood. Current knowledge about CHT1 indicates that stimulated and constitutive exocytosis, in addition to endocytosis, will have major consequences for regulating choline uptake. Future investigations of CHT1 trafficking should elucidate such regulatory mechanisms, which may aid in understanding the pathophysiology of diseases that affect cholinergic neurons, such as Alzheimer's disease.
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Affiliation(s)
- Fabiola M Ribeiro
- Departamento de Bioquímica-Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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44
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Ribeiro FM, Black SAG, Cregan SP, Prado VF, Prado MAM, Rylett RJ, Ferguson SSG. Constitutive high-affinity choline transporter endocytosis is determined by a carboxyl-terminal tail dileucine motif. J Neurochem 2005; 94:86-96. [PMID: 15953352 DOI: 10.1111/j.1471-4159.2005.03171.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Maintenance of acetylcholine synthesis depends on the effective functioning of a high-affinity sodium-dependent choline transporter (CHT1). Recent studies have shown that this transporter is predominantly localized inside the cell, unlike other neurotransmitter transporters, suggesting that the trafficking of CHT1 to and from the plasma membrane may play a crucial role in regulating choline uptake. Here we found that CHT1 is rapidly and constitutively internalized in clathrin-coated vesicles to Rab5-positive early endosomes. CHT1 internalization is controlled by an atypical carboxyl-terminal dileucine-like motif (L531, V532) which, upon replacement by alanine residues, blocks CHT1 internalization in both human embryonic kidney 293 cells and primary cortical neurons and results in both increased CHT1 cell surface expression and choline transport activity. Perturbation of clathrin-mediated endocytosis with dynamin-I K44A increases cell surface expression and transport activity to a similar extent as mutating the dileucine motif, suggesting that we have identified the motif responsible for constitutive CHT1 internalization. Based on the observation that the localization of CHT1 to the plasma membrane is transient, we propose that acetylcholine synthesis may be influenced by processes that lead to the attenuation of constitutive CHT1 endocytosis.
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Affiliation(s)
- Fabiola M Ribeiro
- Cell Biology Research Group, Robarts Research Institute, University of Western Ontario, London, Canada
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45
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Hossain MM, Suzuki T, Sato I, Takewaki T, Suzuki K, Kobayashi H. Neuromechanical effects of pyrethroids, allethrin, cyhalothrin and deltamethrin on the cholinergic processes in rat brain. Life Sci 2005; 77:795-807. [PMID: 15936353 DOI: 10.1016/j.lfs.2005.01.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Accepted: 01/05/2005] [Indexed: 11/28/2022]
Abstract
Our previous microdialysis study of freely moving rats demonstrated that 3 pyrethroids, allethrin (type I), cyhalothrin (type II) and deltamethrin (type II) differentially modulate acetylcholine (ACh) release in the hippocampus. To better understand the mechanisms of their modulatory effects and also other effects on the cholinergic system in the brain, the activities of ACh hydrolyzing enzyme acetylcholinesterase (AChE), ACh synthesizing enzyme choline acetyltransferase (ChAT) and ACh synthesizing rate-limiting step, high-affinity choline uptake (HACU) were examined in the present study. The pyrethroids studied had no effect on AChE activity in the cortex, hippocampus and striatum. These pyrethroids had no significant effect on ChAT in the cortex and hippocampus, but striatal ChAT was increased at higher dosage (60 mg/kg) by all three compounds. Lineweaver-Burk analysis of hippocampal HACU revealed that the pyrethroids did not alter the Michaelis-Menten constant (Km) value but caused alteration of maximal velocity (Vmax). Allethrin (60 mg/kg) and cyhalothrin (20 and 60 mg/kg) decreased while deltamethrin (60 mg/kg) increased the Vmax for HACU. In vitro study showed that at higher concentrations (> or = 10(-) (6) M) allethrin and cyhalothrin reduced the hippocampal HACU but deltamethrin increased it. These results suggest that mechanisms of ACh synthesis are involved in the modulatory effects of the pyrethroids on ACh release and other cholinergic activities.
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Affiliation(s)
- Muhammad Mubarak Hossain
- Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan.
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Traiffort E, Ruat M, O'Regan S, Meunier FM. Molecular characterization of the family of choline transporter-like proteins and their splice variants. J Neurochem 2005; 92:1116-25. [PMID: 15715662 DOI: 10.1111/j.1471-4159.2004.02962.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We show here that the choline transporter-like (CTL) family is more extensive than initially described with five genes in humans and complex alternative splicing. In adult rat tissues, CTL2-4 mRNAs are mainly detected in peripheral tissues, while CTL1 is widely expressed throughout the nervous system. During rat post-natal development, CTL1 is expressed in several subpopulations of neurones and in the white matter, where its spatio-temporal distribution profile recalls that of myelin basic protein, an oligodendrocyte marker. We identified two major rat splice variants of CTL1 (CTL1a and CTL1b) differing in their carboxy-terminal tails with both able to increase choline transport after transfection in neuroblastoma cells. In the developing brain, CTL1a is expressed in both neurones and oligodendroglial cells, whereas CTL1b is restricted to oligodendroglial cells. These findings suggest specific roles for CTL1 splice variants in both neuronal and oligodendrocyte physiology.
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Affiliation(s)
- E Traiffort
- Institut de Neurobiologie Alfred Fessard IFR 2118 CNRS, Laboratoire de Neurobiologie Cellulaire et Moléculaire, UPR 9040, Gif-sur-Yvette, France.
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Abstract
Cholinergic projections to the cortex and hippocampus mediate fundamental cognitive processes. The capacity of the high-affinity choline uptake transporter (CHT) to import choline from the extracellular space to presynaptic terminals is essential for normal acetylcholine synthesis and therefore cholinergic transmission. The CHT is highly regulated, and the cellular mechanisms that modulate its capacity show considerable plasticity. Recent evidence links changes in CHT capacity with the ability to perform tasks that tax attentional processes and capacities. Abnormal regulation of CHT capacity might contribute to the cognitive impairments that are associated with neurodegenerative and neuropsychiatric disorders. Therefore, the CHT might represent a productive target for the development of new pharmacological treatments for these conditions.
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Affiliation(s)
- Martin Sarter
- Department of Psychology, University of Michigan, 4032 East Hall, 525 East University Avenue, Ann Arbor, Michigan 48109, USA.
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Lecomte MJ, De Gois S, Guerci A, Ravassard P, Faucon Biguet N, Mallet J, Berrard S. Differential expression and regulation of the high-affinity choline transporter CHT1 and choline acetyltransferase in neurons of superior cervical ganglia. Mol Cell Neurosci 2005; 28:303-13. [PMID: 15691711 DOI: 10.1016/j.mcn.2004.09.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2004] [Revised: 09/17/2004] [Accepted: 09/22/2004] [Indexed: 11/21/2022] Open
Abstract
Previous studies revealed that leukemia inhibitory factor (LIF) and retinoic acid (RA) induce a noradrenergic to cholinergic switch in cultured sympathetic neurons of superior cervical ganglia (SCG) by up-regulating the coordinate expression of choline acetyltransferase (ChAT) and the vesicular acetylcholine transporter. Here, we examined the effect of both factors on high-affinity choline uptake (HACU) and on expression of the high-affinity choline transporter CHT1. We found that HACU and CHT1-mRNA levels are up-regulated by LIF and down-regulated by RA in these neurons. Thus, in contrast to LIF, RA differentially regulates the expression of the presynaptic cholinergic proteins. Moreover, we showed that untreated SCG neurons express HACU and CHT1-mRNAs at much higher levels than ChAT activity and transcripts. In intact SCG, CHT1-mRNAs are abundant and synthesized by the noradrenergic neurons themselves. This study provides the first example of CHT1 expression in neurons which do not use acetylcholine as neurotransmitter.
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Affiliation(s)
- Marie-José Lecomte
- Laboratoire de la Neurotransmission et des Processus Neurodégénératifs, CNRS, UMR 7091, Bâtiment CERVI, Hôpital de la Pitié-Salpêtrière, 83 boulevard de l'Hôpital, 75013 Paris, France
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49
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Abstract
Identification of the genes and gene products involved in the biosynthesis of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine has lagged behind that in many other fields because of difficulties encountered in purifying the respective proteins. Nevertheless, most of these genes have now been identified. In this review article, we have highlighted important new findings on the individual enzymes and the corresponding genes of phosphatidylcholine synthesis via its two major biosynthetic pathways: the CDP-choline pathway and the methylation pathway. We also review recent studies on phosphatidylethanolamine biosynthesis by two pathways: the CDP-ethanolamine pathway, which is active in the endoplasmic reticulum, and the phosphatidylserine decarboxylase pathway, which operates in mitochondria. Finally, the two base-exchange enzymes, phosphatidylserine synthase-1 and phosphatidylserine synthase-2, that synthesize phosphatidylserine in mammalian cells are also discussed.
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Affiliation(s)
- Jean E Vance
- Department of Medicine and CIHR Group on the Molecualr and Cell Biology of Lipids, University of Alberta, Edmonton, Canada.
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Vatury O, Barg J, Slotkin TA, Yanai J. Altered localization of choline transporter sites in the mouse hippocampus after prenatal heroin exposure. Brain Res Bull 2004; 63:25-32. [PMID: 15121236 DOI: 10.1016/j.brainresbull.2003.11.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2003] [Revised: 11/15/2003] [Accepted: 11/30/2003] [Indexed: 10/26/2022]
Abstract
Prenatal heroin exposure disrupts hippocampal cholinergic synaptic function and related behaviors. Biochemical studies indicate an increase in the number of presynaptic high-affinity choline transporter (HACT) sites, as assessed by [3H]hemicholinium-3 (HC-3) binding. The present study was designed to assess whether this effect involves global upregulation of the transporter, or whether disruption occurs with a specific tempero-spatial distribution. Pregnant mice were given 10mg/kg per day of heroin subcutaneously on gestational days (GD) 9-18. Autoradiographic distribution of HC-3 binding sites was evaluated in the hippocampus of the offspring at postnatal days 15, 25, and 53. These results, suggestive of hippocampal "miswiring," are likely to explain the net impairment of cholinergic synaptic function after prenatal heroin exposure, despite the simultaneous upregulation of both presynaptic cholinergic activity and postsynaptic receptors. Understanding the subregional selectivity of hippocampal defects can lead to the development of strategies that may potentially enable therapeutic interventions to offset or reverse the neurobehavioral defects.
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Affiliation(s)
- Ori Vatury
- The Ross Laboratory for Studies in Neural Birth Defects, Department of Anatomy and Cell Biology, The Hebrew University-Hadassah Medical School, Box 12272, 91120 Jerusalem, Israel
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