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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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Kristofikova Z, Ricny J, Soukup O, Korabecny J, Nepovimova E, Kuca K, Ripova D. Inhibitors of Acetylcholinesterase Derived from 7-Methoxytacrine and Their Effects on the Choline Transporter CHT1. Dement Geriatr Cogn Disord 2018; 43:45-58. [PMID: 27988521 DOI: 10.1159/000453256] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/08/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Reversible acetylcholinesterase inhibitors are used in Alzheimer disease therapy. However, tacrine and its derivatives have severe side effects. Derivatives of the tacrine analogue 7-methoxytacrine (MEOTA) are less toxic. METHODS We evaluated new derivatives of 7-MEOTA (2 homodimers linked by 2 C4-C5 chains and 5 N-alkylated C4-C8 side chain derivatives) in vitro, using the rat hippocampal choline transporter CHT1. RESULTS Some derivatives were effective inhibitors of rat acetylcholinesterase and comparable with 7-MEOTA. All derivatives were able to inhibit CHT1, probably via quaternary ammonium, and this interaction could be involved in the enhancement of their detrimental side effects and/or in the attenuation of their promising effects. Under conditions of disrupted lipid rafts, the unfavorable effects of some derivatives were weakened. Only tacrine was probably able to stereospecifically interact with the naturally occurring amyloid-β isoform and to simultaneously stimulate CHT1. Some derivatives, when coincubated with amyloid β, did not influence CHT1. All derivatives also increased the fluidity of the cortical membranes. CONCLUSION The N-alkylated derivative of 7-MEOTA bearing from C4 side chains appears to be the most promising compound and should be evaluated in future in vivo research.
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Affiliation(s)
- Zdenka Kristofikova
- Alzheimer Disease Center, National Institute of Mental Health, Klecany, Czech Republic
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Ray B, Bailey JA, Simon JR, Lahiri DK. High-affinity choline uptake (HACU) and choline acetyltransferase (ChAT) activity in neuronal cultures for mechanistic and drug discovery studies. ACTA ACUST UNITED AC 2013; Chapter 7:Unit 7.23. [PMID: 22752895 DOI: 10.1002/0471142301.ns0723s60] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Acetylcholine (ACh) is the neurotransmitter used by cholinergic neurons at the neuromuscular junction, in parasympathetic peripheral nerve terminals, and in important memory-related circuits in the brain, and takes part in other critical functions. ACh is synthesized from choline and acetyl coenzyme A by the enzyme choline acetyltransferase (ChAT). The formation of ACh in cholinergic nerve terminals requires the transport of choline into cells from the extracellular space and the activity of ChAT. High-affinity choline uptake (HACU) represents the majority of choline uptake into the nerve terminal and is the acutely regulated, rate-limiting step in ACh synthesis. HACU can be differentiated from nonspecific choline uptake by inhibition of the choline transporter with hemicholinium. Several methods have been described previously to measure HACU and ChAT activity simultaneously in synaptosomes, but a well-documented protocol for cultured cells is lacking. We describe a procedure for simultaneous measurement of HACU and ChAT in cultured cells by simple radionuclide-based techniques. Using this procedure, we have quantitatively determined HACU and ChAT activity in cholinergically differentiated human neuroblastoma (SK-N-SH) cells. These simple methods can be used for neurochemical and drug discovery studies relevant to several disorders, including Alzheimer's disease, myasthenia gravis, and cardiovascular disease.
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Affiliation(s)
- Balmiki Ray
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Electrochemical detection of acetylcholine and choline: application to the quantitative nonradiochemical evaluation of choline transport. Anal Bioanal Chem 2008; 392:651-62. [DOI: 10.1007/s00216-008-2307-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Accepted: 07/17/2008] [Indexed: 01/31/2023]
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Cai S, Mukherjee J, Viranga Tillekeratne LM, Hudson RA, Kirchhoff JR. Inhibition of choline transport by redox-active cholinomimetic bis-catechol reagents. Bioorg Med Chem 2007; 15:7042-7. [PMID: 17827016 PMCID: PMC2094012 DOI: 10.1016/j.bmc.2007.07.041] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Revised: 07/18/2007] [Accepted: 07/19/2007] [Indexed: 02/06/2023]
Abstract
Both N,N'-(2,3-dihydroxybenzyl)-N,N,N',N'-tetramethyl-1,6-hexanediamine dibromide (DTH, 6) and N,N'-(2,3-dihydroxybenzyl)-N,N,N',N'-tetramethyl-1,10-decanediamine dibromide (DTD, 7), which are symmetrical bis-catechol substituted hexamethonium and decamethonium analogues, respectively, were found to inhibit high-affinity choline transport in mouse brain synaptosomes. Inhibitory properties were evaluated using an extraordinarily sensitive capillary electrophoresis method employing electrochemical detection at an enzyme-modified microelectrode. Dose-response curves were generated for each inhibitor and IC(50) values were determined to be 76 microM for 6 and 21 microM for 7. Lineweaver-Burk analysis revealed that both molecules inhibit high-affinity choline uptake by a mixed inhibition mechanism. The K(I) values for 6 and 7 were determined to be 73+/-1 and 31+/-2 microM, respectively. The inhibition properties were further compared to a series of mono-catechol analogues, 3-[(trimethylammonio)methyl]catechol (1), N,N-dimethylepinephrine (4) and 6-hydroxy-N,N-dimethylepinephrine (5), as well as the well-characterized hemicholinium inhibitors, hemicholinium-15 (HC-15, 8) and hemicholinum-3 (HC-3, 9).
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Affiliation(s)
- Shuang Cai
- Department of Chemistry, College of Arts & Sciences, The University of Toledo, Toledo, Ohio 43606
| | - Jhindan Mukherjee
- Department of Chemistry, College of Arts & Sciences, The University of Toledo, Toledo, Ohio 43606
| | - L. M. Viranga Tillekeratne
- Department of Medicinal and Biological Chemistry, College of Pharmacy, The University of Toledo, Toledo, Ohio 43606
| | - Richard A. Hudson
- Department of Chemistry, College of Arts & Sciences, The University of Toledo, Toledo, Ohio 43606
- Department of Medicinal and Biological Chemistry, College of Pharmacy, The University of Toledo, Toledo, Ohio 43606
| | - Jon R. Kirchhoff
- Department of Chemistry, College of Arts & Sciences, The University of Toledo, Toledo, Ohio 43606
- Correspondence to: Jon R. Kirchhoff, Department of Chemistry, The University of Toledo, 2801 W. Bancroft St., Toledo, Ohio 43606, Phone: (419) 530-1515, Fax: (419) 530-4033,
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Kobayashi H, Suzuki T, Kasashima Y, Motegi A, Sato I, Matsusaka N, Ono N, Miura A, Saito F, Saito S. Effects of tri-, di- and monobutyltin on synaptic parameters of the cholinergic system in the cerebral cortex of mice. JAPANESE JOURNAL OF PHARMACOLOGY 1996; 72:317-24. [PMID: 9015740 DOI: 10.1254/jjp.72.317] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Triorganotin compounds like tributyltin have been reported to be biodegraded to diorganotin, monoorganotin and then inorganic tin in animals after they have been ingested. Effects of tributyltin, dibutyltin and monobutyltin on various cholinergic parameters that are involved in synaptic transmission in the mouse cerebral cortex were investigated in vitro. Tributyltin and dibutyltin, but not monobutyltin, inhibited the activity of choline acetyltransferase, both the high-affinity and low-affinity uptakes of choline into synaptosomes, and the binding of [3H]quinuclidinyl benzilate to muscarinic acetylcholine receptors. Tributyltin and dibutyltin, but not monobutyltin, had a slightly suppressive effect on the K(+)-induced release and synthesis of acetylcholine in slices of the cortex. All three butyltins at concentrations from 10(-6) to 10(-4) M had no effect on the activity of acetylcholinesterase. The extent of the inhibitory effects on the cholinergic parameters, apart from the activity of acetylcholinesterase, was slightly greater in the case of tributyltin than dibutyltin, in particularly at the highest concentration (10(-4) M) tested. Therefore, it is concluded that tributyltin metabolites inhibit various parameters of cholinergic activity with a potency ranking of tributyltin > dibutyltin > monobutyltin.
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Affiliation(s)
- H Kobayashi
- Department of Veterinary Pharmacology, Faculty of Agriculture, Iwate University, Morioka, Japan
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Cannon JG. Structure-activity aspects of hemicholinium-3 (HC-3) and its analogs and congeners. Med Res Rev 1994; 14:505-31. [PMID: 7815851 DOI: 10.1002/med.2610140503] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- J G Cannon
- Division of Medicinal and Natural Products Chemistry, College of Pharmacy, University of Iowa, Iowa City 52242
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Van Winkle LJ, Campione AL, Mann DF, Wasserlauf HG. The cation receptor subsite of the choline transporter in preimplantation mouse conceptuses resembles a cation receptor subsite of several amino acid transporters. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1146:38-44. [PMID: 8443225 DOI: 10.1016/0005-2736(93)90335-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Mediated choline transport in preimplantation mouse conceptuses was inhibited competitively by Na+ and other cationic osmolites. Uptake of choline by conceptuses was also inhibited relatively strongly by ethanolamine, hemicholinium-3, harmaline, harmalol and harmine. The Ki values for inhibition of choline transport by most of the latter inhibitors were of the same order of magnitude as the Km value for choline transport (approximately 100 microM). To our knowledge, we are the first to show that mediated 'Na(+)-independent' choline transport is, nevertheless, inhibited strongly by the Na(+)-site inhibitor, harmaline. Inhibitions by harmaline, Na+ and other cations have been used to draw a parallel between the substrate receptor sites of amino acid transport systems y+ and bo.+. We suggest that the latter parallel should be extended to include the Na(+)-independent mammalian choline transporter. In addition, the choline transport activity in conceptuses increased by more than 100-fold between the 2-cell and blastocyst stages of development. Mouse blastocysts probably utilize choline for the synthesis of membrane phospholipids during cellular differentiation and when they begin to grow about ten hours prior to implantation. Since we show here that mouse conceptuses develop the capacity to transport choline prior to the onset of growth, some of the choline utilized for growth could come from an exogenous source.
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Affiliation(s)
- L J Van Winkle
- Department of Biochemistry, Chicago College of Osteopathic Medicine, IL 60515
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Kobayashi H, Saito F, Yuyama A. Effects of organotins on the cholinergic system in the chicken brain in vitro. Toxicol In Vitro 1992; 6:337-43. [DOI: 10.1016/0887-2333(92)90023-k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/1991] [Revised: 01/23/1992] [Indexed: 11/30/2022]
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McMahon HT, Nicholls DG. The bioenergetics of neurotransmitter release. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1059:243-64. [PMID: 1680396 DOI: 10.1016/s0005-2728(05)80210-5] [Citation(s) in RCA: 95] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- H T McMahon
- Department of Biochemistry, University of Dundee, U.K
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11
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Sheff KY, Yorek MA, Long JP. Hemicholinium-3 derivatives A-4 and A-5 affect choline and acetylcholine metabolism. Eur J Pharmacol 1991; 206:105-12. [PMID: 2065716 DOI: 10.1016/0922-4106(91)90018-d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The neuroblastoma-glioma hybrid cell (NG108-15) has a sodium-dependent, high-affinity choline transport system with a Km of 16.0 +/- 3.4 microM and a Vmax of 214.5 +/- 27.7 pmol/min/mg protein. A-4, A-5 and HC-3 produce dose-dependent inhibition of high-affinity choline transport in NG108-15 cells. Following 24 h exposure to approximately the EC50 of each inhibitor, no significant decrease was found in total choline accumulation or in choline incorporation into phosphatidylcholine. However, when additional inhibitor was added during the 24 h incubation, significant decreases in choline accumulation were produced by A-4 and A-5. Following 24 h exposure to each compound, only A-4 was able to significantly affect free choline content. In contrast, each inhibitor was able to significantly decrease acetylcholine content following 24 h exposure. Possible reasons for consistent decreases in acetylcholine versus minimal changes in choline metabolism will be discussed.
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Affiliation(s)
- K Y Sheff
- Department of Pharmacology, College of Medicine, University of Iowa, Iowa City 52242
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12
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Chatterjee TK, Bhatnagar RK. Ca2(+)-dependent, ATP-induced conversion of the [3H]hemicholinium-3 binding sites from high- to low-affinity states in rat striatum: effect of protein kinase inhibitors on this affinity conversion and synaptosomal choline transport. J Neurochem 1990; 54:1500-8. [PMID: 2324736 DOI: 10.1111/j.1471-4159.1990.tb01197.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Tritium-labeled hemicholinium-3 ([3H]HC-3) was used to characterize the sodium-dependent high-affinity choline carrier sites in rat striatal preparations. In an earlier study, we had shown that [3H]HC-3 labels choline carrier sites with high and low affinities and had suggested that the low-affinity sites represent "functional" carrier sites. The objective of the present study was to examine the mechanisms involved in the regulation of the two affinity states of [3H]HC-3 binding. Here, we demonstrate that these two affinity states are totally interconvertible; addition of 0.1 mM ATP in the binding assay medium quantitatively converted all the binding sites to the low-affinity state, whereas addition of 1 mM beta,gamma-methylene 5'-ATP quantitatively converted all the binding sites to the high-affinity state. Preincubation of the tissue (for 15 min at 37 degrees C) before the binding assay also converted the binding sites to the high-affinity state, whereas supplementation of the assay medium with ATP (0.5 mM) again induced expression of the low-affinity state of the binding sites. This effect of ATP was found to be selective for this nucleotide. Neither ADP (1 mM) nor cyclic AMP could mimic such an effect. Other nucleotide triphosphates--CTP (0.5 mM) and GTP (0.5 mM)--also could not substitute for ATP. GTP, however, caused nearly a 35% reduction in the number of binding sites, accompanying a loss of the low-affinity component of binding. This effect of GTP was also shared by 5'-guanylylimidodiphosphate but not by GDP or cyclic GMP. This ATP-dependent low-affinity conversion of [3H]HC-3 binding sites requires divalent metal ions.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- T K Chatterjee
- Department of Pharmacology, College of Medicine, University of Iowa, Iowa City 52242
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