1
|
Rizvi M, Truong TK, Zhou J, Batta M, Moran ES, Pappas J, Chu ML, Caluseriu O, Evrony GD, Leslie EM, Cordat E. Biochemical characterization of two novel mutations in the human high-affinity choline transporter 1 identified in a patient with congenital myasthenic syndrome. Hum Mol Genet 2023; 32:1552-1564. [PMID: 36611016 DOI: 10.1093/hmg/ddac309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/21/2022] [Accepted: 12/22/2022] [Indexed: 01/09/2023] Open
Abstract
Congenital myasthenic syndrome (CMS) is a heterogeneous condition associated with 34 different genes, including SLC5A7, which encodes the high-affinity choline transporter 1 (CHT1). CHT1 is expressed in presynaptic neurons of the neuromuscular junction where it uses the inward sodium gradient to reuptake choline. Biallelic CHT1 mutations often lead to neonatal lethality, and less commonly to non-lethal motor weakness and developmental delays. Here, we report detailed biochemical characterization of two novel mutations in CHT1, p.I294T and p.D349N, which we identified in an 11-year-old patient with a history of neonatal respiratory distress, and subsequent hypotonia and global developmental delay. Heterologous expression of each CHT1 mutant in human embryonic kidney cells showed two different mechanisms of reduced protein function. The p.I294T CHT1 mutant transporter function was detectable, but its abundance and half-life were significantly reduced. In contrast, the p.D349N CHT1 mutant was abundantly expressed at the cell membrane, but transporter function was absent. The residual function of the p.I294T CHT1 mutant may explain the non-lethal form of CMS in this patient, and the divergent mechanisms of reduced CHT1 function that we identified may guide future functional studies of the CHT1 myasthenic syndrome. Based on these in vitro studies that provided a diagnosis, treatment with cholinesterase inhibitor together with physical and occupational therapy significantly improved the patient's strength and quality of life.
Collapse
Affiliation(s)
- Midhat Rizvi
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Tina K Truong
- Center for Human Genetics and Genomics, New York University Grossman School of Medicine, New York, NY, USA
| | - Janet Zhou
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Manav Batta
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Ellen S Moran
- Clinical Genetics, New York University Langone Orthopedic Hospital, New York, NY, USA
| | - John Pappas
- Division of Clinical Genetics, Department of Pediatrics, New York University Grossman School of Medicine, New York, NY, USA
| | - Mary Lynn Chu
- Department of Neurology, New York University School of Medicine, New York, NY, USA
| | - Oana Caluseriu
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Gilad D Evrony
- Center for Human Genetics and Genomics, New York University Grossman School of Medicine, New York, NY, USA
- Department of Pediatrics, Department of Neuroscience and Physiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Elaine M Leslie
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Emmanuelle Cordat
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| |
Collapse
|
2
|
Ojiakor O, Rylett R. Modulation of sodium-coupled choline transporter CHT function in health and disease. Neurochem Int 2020; 140:104810. [DOI: 10.1016/j.neuint.2020.104810] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 06/16/2020] [Accepted: 07/09/2020] [Indexed: 12/27/2022]
|
3
|
Impaired hippocampal and thalamic acetylcholine release in P301L tau-transgenic mice. Brain Res Bull 2019; 152:134-142. [DOI: 10.1016/j.brainresbull.2019.07.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 06/21/2019] [Accepted: 07/12/2019] [Indexed: 11/23/2022]
|
4
|
Banerjee M, Arutyunov D, Brandwein D, Janetzki-Flatt C, Kolski H, Hume S, Leonard NJ, Watt J, Lacson A, Baradi M, Leslie EM, Cordat E, Caluseriu O. The novel p.Ser263Phe mutation in the human high-affinity choline transporter 1 (CHT1/SLC5A7) causes a lethal form of fetal akinesia syndrome. Hum Mutat 2019; 40:1676-1683. [PMID: 31299140 DOI: 10.1002/humu.23828] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 05/04/2019] [Accepted: 05/27/2019] [Indexed: 11/07/2022]
Abstract
A subset of a larger and heterogeneous class of disorders, the congenital myasthenic syndromes (CMS) are caused by pathogenic variants in genes encoding proteins that support the integrity and function of the neuromuscular junction (NMJ). A central component of the NMJ is the sodium-dependent high-affinity choline transporter 1 (CHT1), a solute carrier protein (gene symbol SLC5A7), responsible for the reuptake of choline into nerve termini has recently been implicated as one of several autosomal recessive causes of CMS. We report the identification and functional characterization of a novel pathogenic variant in SLC5A7, c.788C>T (p.Ser263Phe) in an El Salvadorian family with a lethal form of a congenital myasthenic syndrome characterized by fetal akinesia. This study expands the clinical phenotype and insight into a form of fetal akinesia related to CHT1 defects and proposes a genotype-phenotype correlation for the lethal form of SLC5A7-related disorder with potential implications for genetic counseling.
Collapse
Affiliation(s)
- Mayukh Banerjee
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Denis Arutyunov
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Daniel Brandwein
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | | | - Hanna Kolski
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Stacey Hume
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
| | - Norma Jean Leonard
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada.,Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - James Watt
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Atilano Lacson
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Monica Baradi
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Elaine M Leslie
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada.,Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Emmanuelle Cordat
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Oana Caluseriu
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada.,Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| |
Collapse
|
5
|
Choudhary P, Armstrong EJ, Jorgensen CC, Piotrowski M, Barthmes M, Torella R, Johnston SE, Maruyama Y, Janiszewski JS, Storer RI, Skerratt SE, Benn CL. Discovery of Compounds that Positively Modulate the High Affinity Choline Transporter. Front Mol Neurosci 2017; 10:40. [PMID: 28289374 PMCID: PMC5326799 DOI: 10.3389/fnmol.2017.00040] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 02/03/2017] [Indexed: 01/09/2023] Open
Abstract
Cholinergic hypofunction is associated with decreased attention and cognitive deficits in the central nervous system in addition to compromised motor function. Consequently, stimulation of cholinergic neurotransmission is a rational therapeutic approach for the potential treatment of a variety of neurological conditions. High affinity choline uptake (HACU) into acetylcholine (ACh)-synthesizing neurons is critically mediated by the sodium- and pH-dependent high-affinity choline transporter (CHT, encoded by the SLC5A7 gene). This transporter is comparatively well-characterized but otherwise unexplored as a potential drug target. We therefore sought to identify small molecules that would enable testing of the hypothesis that positive modulation of CHT mediated transport would enhance activity-dependent cholinergic signaling. We utilized existing and novel screening techniques for their ability to reveal both positive and negative modulation of CHT using literature tools. A screening campaign was initiated with a bespoke compound library comprising both the Pfizer Chemogenomic Library (CGL) of 2,753 molecules designed specifically to help enable the elucidation of new mechanisms in phenotypic screens and 887 compounds from a virtual screening campaign to select molecules with field-based similarities to reported negative and positive allosteric modulators. We identified a number of previously unknown active and structurally distinct molecules that could be used as tools to further explore CHT biology or as a starting point for further medicinal chemistry.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Yuya Maruyama
- Central Research Laboratory, Kissei Pharmaceutical Co., Ltd. Nagano, Japan
| | | | - R Ian Storer
- Pfizer, Worldwide Medicinal Chemistry Cambridge, UK
| | | | | |
Collapse
|
6
|
Insulin Regulates the Activity of the High-Affinity Choline Transporter CHT. PLoS One 2015; 10:e0132934. [PMID: 26161852 PMCID: PMC4498808 DOI: 10.1371/journal.pone.0132934] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 06/21/2015] [Indexed: 12/22/2022] Open
Abstract
Studies in humans and animal models show that neuronal insulin resistance increases the risk of developing Alzheimer’s Disease (AD), and that insulin treatment may promote memory function. Cholinergic neurons play a critical role in cognitive and attentional processing and their dysfunction early in AD pathology may promote the progression of AD pathology. Synthesis and release of the neurotransmitter acetylcholine (ACh) is closely linked to the activity of the high-affinity choline transporter protein (CHT), but the impact of insulin receptor signaling and neuronal insulin resistance on these aspects of cholinergic function are unknown. In this study, we used differentiated SH-SY5Y cells stably-expressing CHT proteins to study the effect of insulin signaling on CHT activity and function. We find that choline uptake activity measured after acute addition of 20 nM insulin is significantly lower in cells that were grown for 24 h in media containing insulin compared to cells grown in the absence of insulin. This coincides with loss of ability to increase phospho-Protein Kinase B (PKB)/Akt levels in response to acute insulin stimulation in the chronic insulin-treated cells. Inhibition of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3-kinase) in cells significantly lowers phospho-PKB/Akt levels and decreases choline uptake activity. We show total internal reflection microscopy (TIRF) imaging of the dynamic movement of CHT proteins in live cells in response to depolarization and drug treatments. These data show that acute exposure of depolarized cells to insulin is coupled to transiently increased levels of CHT proteins at the cell surface, and that this is attenuated by chronic insulin exposure. Moreover, prolonged inhibition of PI3-kinase results in enhanced levels of CHT proteins at the cell surface by decreasing their rate of internalization.
Collapse
|
7
|
Ennis EA, Wright J, Retzlaff CL, McManus OB, Lin Z, Huang X, Wu M, Li M, Daniels JS, Lindsley CW, Hopkins CR, Blakely RD. Identification and characterization of ML352: a novel, noncompetitive inhibitor of the presynaptic choline transporter. ACS Chem Neurosci 2015; 6:417-27. [PMID: 25560927 PMCID: PMC4367188 DOI: 10.1021/cn5001809] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
![]()
The high-affinity choline transporter
(CHT) is the rate-limiting
determinant of acetylcholine (ACh) synthesis, yet the transporter
remains a largely undeveloped target for the detection and manipulation
of synaptic cholinergic signaling. To expand CHT pharmacology, we
pursued a high-throughput screen for novel CHT-targeted small molecules
based on the electrogenic properties of transporter-mediated choline
transport. In this effort, we identified five novel, structural classes
of CHT-specific inhibitors. Chemical diversification and functional
analysis of one of these classes identified ML352 as a high-affinity
(Ki = 92 nM) and selective CHT inhibitor.
At concentrations that fully antagonized CHT in transfected cells
and nerve terminal preparations, ML352 exhibited no inhibition of
acetylcholinesterase (AChE) or cholineacetyltransferase (ChAT) and
also lacked activity at dopamine, serotonin, and norepinephrine transporters,
as well as many receptors and ion channels. ML352 exhibited noncompetitive
choline uptake inhibition in intact cells and synaptosomes and reduced
the apparent density of hemicholinium-3 (HC-3) binding sites in membrane
assays, suggesting allosteric transporter interactions. Pharmacokinetic
studies revealed limited in vitro metabolism and
significant CNS penetration, with features predicting rapid clearance.
ML352 represents a novel, potent, and specific tool for the manipulation
of CHT, providing a possible platform for the development of cholinergic
imaging and therapeutic agents.
Collapse
Affiliation(s)
| | | | | | - Owen B. McManus
- Johns Hopkins University Ion Channel Center, Baltimore, Maryland 21205, United States
| | - Zhinong Lin
- Johns Hopkins University Ion Channel Center, Baltimore, Maryland 21205, United States
| | - Xiaofang Huang
- Johns Hopkins University Ion Channel Center, Baltimore, Maryland 21205, United States
| | - Meng Wu
- Johns Hopkins University Ion Channel Center, Baltimore, Maryland 21205, United States
| | - Min Li
- Johns Hopkins University Ion Channel Center, Baltimore, Maryland 21205, United States
| | | | | | | | | |
Collapse
|
8
|
Cuddy LK, Winick-Ng W, Rylett RJ. Regulation of the high-affinity choline transporter activity and trafficking by its association with cholesterol-rich lipid rafts. J Neurochem 2013; 128:725-40. [PMID: 24127780 DOI: 10.1111/jnc.12490] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 10/10/2013] [Accepted: 10/14/2013] [Indexed: 01/07/2023]
Abstract
The sodium-coupled, hemicholinium-3-sensitive, high-affinity choline transporter (CHT) is responsible for transport of choline into cholinergic nerve terminals from the synaptic cleft following acetylcholine release and hydrolysis. In this study, we address regulation of CHT function by plasma membrane cholesterol. We show for the first time that CHT is concentrated in cholesterol-rich lipid rafts in both SH-SY5Y cells and nerve terminals from mouse forebrain. Treatment of SH-SY5Y cells expressing rat CHT with filipin, methyl-β-cyclodextrin (MβC) or cholesterol oxidase significantly decreased choline uptake. In contrast, CHT activity was increased by addition of cholesterol to membranes using cholesterol-saturated MβC. Kinetic analysis of binding of [(3)H]hemicholinium-3 to CHT revealed that reducing membrane cholesterol with MβC decreased both the apparent binding affinity (KD) and maximum number of binding sites (Bmax ); this was confirmed by decreased plasma membrane CHT protein in lipid rafts in cell surface protein biotinylation assays. Finally, the loss of cell surface CHT associated with lipid raft disruption was not because of changes in CHT internalization. In summary, we provide evidence that CHT association with cholesterol-rich rafts is critical for transporter function and localization. Alterations in plasma membrane cholesterol cholinergic nerve terminals could diminish cholinergic transmission by reducing choline availability for acetylcholine synthesis. The sodium-coupled choline transporter CHT moves choline into cholinergic nerve terminals to serve as substrate for acetylcholine synthesis. We show for the first time that CHT is concentrated in cholesterol-rich lipid rafts, and decreasing membrane cholesterol significantly reduces both choline uptake activity and cell surface CHT protein levels. CHT association with cholesterol-rich rafts is critical for its function, and alterations in plasma membrane cholesterol could diminish cholinergic transmission by reducing choline availability for acetylcholine synthesis.
Collapse
Affiliation(s)
- Leah K Cuddy
- Molecular Brain Research Group, Robarts Research Institute, Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada
| | | | | |
Collapse
|
9
|
Mohr F, Zimmermann M, Klein J. Mice heterozygous for AChE are more sensitive to AChE inhibitors but do not respond to BuChE inhibition. Neuropharmacology 2013; 67:37-45. [DOI: 10.1016/j.neuropharm.2012.11.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 10/17/2012] [Accepted: 11/01/2012] [Indexed: 01/22/2023]
|
10
|
Staurosporine-induced apoptosis presents with unexpected cholinergic effects in a differentiated neuroblastoma cell line. Neurochem Int 2012; 61:1011-20. [DOI: 10.1016/j.neuint.2012.07.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 06/29/2012] [Accepted: 07/19/2012] [Indexed: 11/20/2022]
|
11
|
Peroxynitrite donor SIN-1 alters high-affinity choline transporter activity by modifying its intracellular trafficking. J Neurosci 2012; 32:5573-84. [PMID: 22514319 DOI: 10.1523/jneurosci.5235-11.2012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Sodium-coupled, high-affinity choline transporters (CHTs) are inhibited by 3-morpholinosydnonimine (SIN-1) [peroxynitrite (ONOO⁻) donor]; ONOO⁻ can be produced from nitric oxide and reactive oxygen species during neurodegeneration. SIN-1 rapidly increases CHT internalization from the cell surface, and this correlates with decreased choline uptake. This study addresses mechanisms by which SIN-1 inhibits CHT function in human neuronal SH-SY5Y cells. Thus, mutant L531A-CHT, which does not constitutively internalize into cells by a clathrin-mediated process, is resistant to SIN-1 effects. This suggests that CHT inhibition is not due to oxidative-nitrosative inactivation of the protein and that decreased levels of cell surface CHT in SIN-1-treated cells is related to alterations in its trafficking and subcellular disposition. Dominant-negative proteins AP180C and dynamin-K44A, which interfere with clathrin-mediated and dynamin-dependent endocytosis, respectively, attenuate CHT inhibition by SIN-1. CHT in both vehicle- and SIN-1-treated cells colocalizes with Rab7, Rab9, and Lamp-1 in late endosomes and lysosomes to a similar extent. Lysosome inhibitors increase choline uptake, suggesting that CHT proteins are normally degraded by lysosomes, and this is not altered by oxidative stress. Unexpectedly, inhibitors of proteasomes, but not lysosomes, attenuate SIN-1-mediated inhibition of choline uptake, indicating that proteasomal degradation plays a role in regulating CHT disposition in SIN-1-treated cells. SIN-1 treatment also enhances CHT ubiquitination. Thus, CHT inhibition in SIN-1-treated cells is mediated by proteasomal degradation, which differs from inhibitory mechanisms for some neurotransmitter transporters under similar conditions. Increased oxidative-nitrosative stress in the microenvironment of cholinergic nerve terminals would diminish cholinergic transmission by reducing choline availability for ACh synthesis.
Collapse
|
12
|
Samluk Ł, Czeredys M, Nałęcz KA. Regulation of amino acid/carnitine transporter B 0,+ (ATB 0,+) in astrocytes by protein kinase C: independent effects on raft and non-raft transporter subpopulations. J Neurochem 2010; 115:1386-97. [PMID: 20977479 DOI: 10.1111/j.1471-4159.2010.07040.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Neutral and basic amino acid transporter B(0,+) belongs to a Na,Cl-dependent superfamily of proteins transporting neurotransmitters, amino acids and osmolytes, known to be regulated by protein kinase C (PKC). The present study demonstrates an increased phosphorylation of B(0,+) on serine moiety after treatment of rat astrocytes with phorbol 12-myristate 13-acetate, a process correlated with an augmented activity of l-leucine transport and an enhanced presence of the transporter at the cell surface. After solubilization with Triton X-100 and sucrose gradient centrifugation, B(0,+) was detected in non-raft as well as in detergent-resistant raft fractions under control conditions, while phorbol 12-myristate 13-acetate treatment resulted in a complete disappearance of the transporter from the raft fraction. B(0,+) was observed to interact with caveolin-1 and flotillin-1 (reggie-2) proteins, the markers of detergent-resistant microdomains of plasma membrane. As verified in immunocytochemistry and immunoprecipitation experiments, modification of PKC activity did not affect these interactions. It is proposed that PKC reveals different effects on raft and non-raft subpopulations of B(0,+). Phorbol ester treatment results in trafficking of the transporter from the intracellular pool to non-raft microdomains and increased activity, while B(0,+) present in raft microdomains undergoes either internalization or is transferred laterally to non-raft domains.
Collapse
Affiliation(s)
- Łukasz Samluk
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Warsaw, Poland
| | | | | |
Collapse
|