1
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Scott H, Novikov B, Ugur B, Allen B, Mertsalov I, Monagas-Valentin P, Koff M, Baas Robinson S, Aoki K, Veizaj R, Lefeber DJ, Tiemeyer M, Bellen H, Panin V. Glia-neuron coupling via a bipartite sialylation pathway promotes neural transmission and stress tolerance in Drosophila. eLife 2023; 12:e78280. [PMID: 36946697 PMCID: PMC10110239 DOI: 10.7554/elife.78280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 03/16/2023] [Indexed: 03/23/2023] Open
Abstract
Modification by sialylated glycans can affect protein functions, underlying mechanisms that control animal development and physiology. Sialylation relies on a dedicated pathway involving evolutionarily conserved enzymes, including CMP-sialic acid synthetase (CSAS) and sialyltransferase (SiaT) that mediate the activation of sialic acid and its transfer onto glycan termini, respectively. In Drosophila, CSAS and DSiaT genes function in the nervous system, affecting neural transmission and excitability. We found that these genes function in different cells: the function of CSAS is restricted to glia, while DSiaT functions in neurons. This partition of the sialylation pathway allows for regulation of neural functions via a glia-mediated control of neural sialylation. The sialylation genes were shown to be required for tolerance to heat and oxidative stress and for maintenance of the normal level of voltage-gated sodium channels. Our results uncovered a unique bipartite sialylation pathway that mediates glia-neuron coupling and regulates neural excitability and stress tolerance.
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Affiliation(s)
- Hilary Scott
- Department of Biochemistry and Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Boris Novikov
- Department of Biochemistry and Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Berrak Ugur
- Departments of Molecular and Human Genetics and Neuroscience, Baylor College of Medicine, and Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
| | - Brooke Allen
- Department of Biochemistry and Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Ilya Mertsalov
- Department of Biochemistry and Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Pedro Monagas-Valentin
- Department of Biochemistry and Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Melissa Koff
- Department of Biochemistry and Biophysics, Texas A&M UniversityCollege StationUnited States
| | - Sarah Baas Robinson
- Complex Carbohydrate Research Center, University of GeorgiaAthensUnited States
| | - Kazuhiro Aoki
- Complex Carbohydrate Research Center, University of GeorgiaAthensUnited States
| | - Raisa Veizaj
- Translational Metabolic Laboratory, Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical CenterNijmegenNetherlands
| | - Dirk J Lefeber
- Translational Metabolic Laboratory, Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical CenterNijmegenNetherlands
| | - Michael Tiemeyer
- Complex Carbohydrate Research Center, University of GeorgiaAthensUnited States
| | - Hugo Bellen
- Departments of Molecular and Human Genetics and Neuroscience, Baylor College of Medicine, and Jan and Dan Duncan Neurological Research Institute, Texas Children’s HospitalHoustonUnited States
| | - Vladislav Panin
- Department of Biochemistry and Biophysics, Texas A&M UniversityCollege StationUnited States
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2
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Nguyen NH, Brodsky JL. The cellular pathways that maintain the quality control and transport of diverse potassium channels. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194908. [PMID: 36638864 PMCID: PMC9908860 DOI: 10.1016/j.bbagrm.2023.194908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/20/2022] [Accepted: 01/03/2023] [Indexed: 01/12/2023]
Abstract
Potassium channels are multi-subunit transmembrane proteins that permit the selective passage of potassium and play fundamental roles in physiological processes, such as action potentials in the nervous system and organismal salt and water homeostasis, which is mediated by the kidney. Like all ion channels, newly translated potassium channels enter the endoplasmic reticulum (ER) and undergo the error-prone process of acquiring post-translational modifications, folding into their native conformations, assembling with other subunits, and trafficking through the secretory pathway to reach their final destinations, most commonly the plasma membrane. Disruptions in these processes can result in detrimental consequences, including various human diseases. Thus, multiple quality control checkpoints evolved to guide potassium channels through the secretory pathway and clear potentially toxic, aggregation-prone misfolded species. We will summarize current knowledge on the mechanisms underlying potassium channel quality control in the secretory pathway, highlight diseases associated with channel misfolding, and suggest potential therapeutic routes.
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Affiliation(s)
- Nga H Nguyen
- Department of Biological Sciences, University of Pittsburgh, A320 Langley Hall, Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, USA
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, A320 Langley Hall, Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, USA.
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3
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Abad-Rodríguez J, Brocca ME, Higuero AM. Glycans and Carbohydrate-Binding/Transforming Proteins in Axon Physiology. ADVANCES IN NEUROBIOLOGY 2023; 29:185-217. [PMID: 36255676 DOI: 10.1007/978-3-031-12390-0_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The mature nervous system relies on the polarized morphology of neurons for a directed flow of information. These highly polarized cells use their somatodendritic domain to receive and integrate input signals while the axon is responsible for the propagation and transmission of the output signal. However, the axon must perform different functions throughout development before being fully functional for the transmission of information in the form of electrical signals. During the development of the nervous system, axons perform environmental sensing functions, which allow them to navigate through other regions until a final target is reached. Some axons must also establish a regulated contact with other cells before reaching maturity, such as with myelinating glial cells in the case of myelinated axons. Mature axons must then acquire the structural and functional characteristics that allow them to perform their role as part of the information processing and transmitting unit that is the neuron. Finally, in the event of an injury to the nervous system, damaged axons must try to reacquire some of their immature characteristics in a regeneration attempt, which is mostly successful in the PNS but fails in the CNS. Throughout all these steps, glycans perform functions of the outermost importance. Glycans expressed by the axon, as well as by their surrounding environment and contacting cells, encode key information, which is fine-tuned by glycan modifying enzymes and decoded by glycan binding proteins so that the development, guidance, myelination, and electrical transmission functions can be reliably performed. In this chapter, we will provide illustrative examples of how glycans and their binding/transforming proteins code and decode instructive information necessary for fundamental processes in axon physiology.
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Affiliation(s)
- José Abad-Rodríguez
- Membrane Biology and Axonal Repair Laboratory, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain.
| | - María Elvira Brocca
- Membrane Biology and Axonal Repair Laboratory, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain
| | - Alonso Miguel Higuero
- Membrane Biology and Axonal Repair Laboratory, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain
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4
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Nilsson M, Lindström SH, Kaneko M, Wang K, Minguez-Viñas T, Angelini M, Steccanella F, Holder D, Ottolia M, Olcese R, Pantazis A. An epilepsy-associated K V1.2 charge-transfer-center mutation impairs K V1.2 and K V1.4 trafficking. Proc Natl Acad Sci U S A 2022; 119:e2113675119. [PMID: 35439054 PMCID: PMC9169947 DOI: 10.1073/pnas.2113675119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 02/25/2022] [Indexed: 12/19/2022] Open
Abstract
We report on a heterozygous KCNA2 variant in a child with epilepsy. KCNA2 encodes KV1.2 subunits, which form homotetrameric potassium channels and participate in heterotetrameric channel complexes with other KV1-family subunits, regulating neuronal excitability. The mutation causes substitution F233S at the KV1.2 charge transfer center of the voltage-sensing domain. Immunocytochemical trafficking assays showed that KV1.2(F233S) subunits are trafficking deficient and reduce the surface expression of wild-type KV1.2 and KV1.4: a dominant-negative phenotype extending beyond KCNA2, likely profoundly perturbing electrical signaling. Yet some KV1.2(F233S) trafficking was rescued by wild-type KV1.2 and KV1.4 subunits, likely in permissible heterotetrameric stoichiometries: electrophysiological studies utilizing applied transcriptomics and concatemer constructs support that up to one or two KV1.2(F233S) subunits can participate in trafficking-capable heterotetramers with wild-type KV1.2 or KV1.4, respectively, and that both early and late events along the biosynthesis and secretion pathway impair trafficking. These studies suggested that F233S causes a depolarizing shift of ∼48 mV on KV1.2 voltage dependence. Optical tracking of the KV1.2(F233S) voltage-sensing domain (rescued by wild-type KV1.2 or KV1.4) revealed that it operates with modestly perturbed voltage dependence and retains pore coupling, evidenced by off-charge immobilization. The equivalent mutation in the Shaker K+ channel (F290S) was reported to modestly affect trafficking and strongly affect function: an ∼80-mV depolarizing shift, disrupted voltage sensor activation and pore coupling. Our work exposes the multigenic, molecular etiology of a variant associated with epilepsy and reveals that charge-transfer-center disruption has different effects in KV1.2 and Shaker, the archetypes for potassium channel structure and function.
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Affiliation(s)
- Michelle Nilsson
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, 581 83 Linköping, Sweden
| | - Sarah H. Lindström
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, 581 83 Linköping, Sweden
| | - Maki Kaneko
- Center for Personalized Medicine, Children's Hospital Los Angeles, Los Angeles, CA 90027
- Division of Genomic Medicine, Department of Pathology, Children's Hospital Los Angeles, Los Angeles, CA 90027
| | - Kaiqian Wang
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, 581 83 Linköping, Sweden
| | - Teresa Minguez-Viñas
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, 581 83 Linköping, Sweden
| | - Marina Angelini
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Federica Steccanella
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Deborah Holder
- Comprehensive Epilepsy Program, Children's Hospital Los Angeles, Los Angeles, CA 90027
| | - Michela Ottolia
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- UCLA Cardiovascular Theme, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Riccardo Olcese
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- UCLA Cardiovascular Theme, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Antonios Pantazis
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, 581 83 Linköping, Sweden
- Wallenberg Center for Molecular Medicine, Linköping University, 581 83 Linköping, Sweden
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5
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Lin CH, Lin YC, Yang SB, Chen PC. Carbamazepine promotes surface expression of mutant Kir6.2-A28V ATP-sensitive potassium channels by modulating Golgi retention and autophagy. J Biol Chem 2022; 298:101904. [PMID: 35398096 PMCID: PMC9065613 DOI: 10.1016/j.jbc.2022.101904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 03/25/2022] [Accepted: 03/27/2022] [Indexed: 11/21/2022] Open
Abstract
Pancreatic β-cells express ATP-sensitive potassium (KATP) channels, consisting of octamer complexes containing four sulfonylurea receptor 1 (SUR1) and four Kir6.2 subunits. Loss of KATP channel function causes persistent hyperinsulinemic hypoglycemia of infancy (PHHI), a rare but debilitating condition if not treated. We previously showed that the sodium-channel blocker carbamazepine (Carb) corrects KATP channel surface expression defects induced by PHHI-causing mutations in SUR1. In this study, we show that Carb treatment can also ameliorate the trafficking deficits associated with a recently discovered PHHI-causing mutation in Kir6.2 (Kir6.2-A28V). In human embryonic kidney 293 or INS-1 cells expressing this mutant KATP channel (SUR1 and Kir6.2-A28V), biotinylation and immunostaining assays revealed that Carb can increase surface expression of the mutant KATP channels. We further examined the subcellular distributions of mutant KATP channels before and after Carb treatment; without Carb treatment, we found that mutant KATP channels were aberrantly accumulated in the Golgi apparatus. However, after Carb treatment, coimmunoprecipitation of mutant KATP channels and Golgi marker GM130 was diminished, and KATP staining was also reduced in lysosomes. Intriguingly, Carb treatment also simultaneously increased autophagic flux and p62 accumulation, suggesting that autophagy-dependent degradation of the mutant channel was not only stimulated but also interrupted. In summary, our data suggest that surface expression of Kir6.2-A28V KATP channels is rescued by Carb treatment via promotion of mutant KATP channel exit from the Golgi apparatus and reduction of autophagy-mediated protein degradation.
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6
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Govind AP, Jeyifous O, Russell TA, Yi Z, Weigel AV, Ramaprasad A, Newell L, Ramos W, Valbuena FM, Casler JC, Yan JZ, Glick BS, Swanson GT, Lippincott-Schwartz J, Green WN. Activity-dependent Golgi satellite formation in dendrites reshapes the neuronal surface glycoproteome. eLife 2021; 10:68910. [PMID: 34545811 PMCID: PMC8494481 DOI: 10.7554/elife.68910] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 09/20/2021] [Indexed: 11/13/2022] Open
Abstract
Activity-driven changes in the neuronal surface glycoproteome are known to occur with synapse formation, plasticity, and related diseases, but their mechanistic basis and significance are unclear. Here, we observed that N-glycans on surface glycoproteins of dendrites shift from immature to mature forms containing sialic acid in response to increased neuronal activation. In exploring the basis of these N-glycosylation alterations, we discovered that they result from the growth and proliferation of Golgi satellites scattered throughout the dendrite. Golgi satellites that formed during neuronal excitation were in close association with endoplasmic reticulum (ER) exit sites and early endosomes and contained glycosylation machinery without the Golgi structural protein, GM130. They functioned as distal glycosylation stations in dendrites, terminally modifying sugars either on newly synthesized glycoproteins passing through the secretory pathway or on surface glycoproteins taken up from the endocytic pathway. These activities led to major changes in the dendritic surface of excited neurons, impacting binding and uptake of lectins, as well as causing functional changes in neurotransmitter receptors such as nicotinic acetylcholine receptors. Neural activity thus boosts the activity of the dendrite’s satellite micro-secretory system by redistributing Golgi enzymes involved in glycan modifications into peripheral Golgi satellites. This remodeling of the neuronal surface has potential significance for synaptic plasticity, addiction, and disease.
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Affiliation(s)
- Anitha P Govind
- Department of Neurobiology, University of Chicago, Chicago, United States
| | - Okunola Jeyifous
- Department of Neurobiology, University of Chicago, Chicago, United States.,Marine Biological Laboratory, Woods Hole, United States
| | - Theron A Russell
- Department of Neurobiology, University of Chicago, Chicago, United States
| | - Zola Yi
- Department of Neurobiology, University of Chicago, Chicago, United States
| | - Aubrey V Weigel
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Abhijit Ramaprasad
- Department of Neurobiology, University of Chicago, Chicago, United States
| | - Luke Newell
- Department of Neurobiology, University of Chicago, Chicago, United States
| | - William Ramos
- Department of Neurobiology, University of Chicago, Chicago, United States
| | - Fernando M Valbuena
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, United States
| | - Jason C Casler
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, United States
| | - Jing-Zhi Yan
- Department of Pharmacology, Northwestern University, Feinberg School of Medicine, Chicago, United States
| | - Benjamin S Glick
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, United States
| | - Geoffrey T Swanson
- Department of Pharmacology, Northwestern University, Feinberg School of Medicine, Chicago, United States
| | | | - William N Green
- Department of Neurobiology, University of Chicago, Chicago, United States.,Marine Biological Laboratory, Woods Hole, United States
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7
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Okui M, Murakami T, Sun H, Ikeshita C, Kanamura N, Taruno A. Posttranslational regulation of CALHM1/3 channel: N-linked glycosylation and S-palmitoylation. FASEB J 2021; 35:e21527. [PMID: 33788965 DOI: 10.1096/fj.202002632r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 02/08/2021] [Accepted: 03/01/2021] [Indexed: 11/11/2022]
Abstract
Among calcium homeostasis modulator (CALHM) family members, CALHM1 and 3 together form a voltage-gated large-pore ion channel called CALHM1/3. CALHM1/3 plays an essential role in taste perception by mediating neurotransmitter release at channel synapses of taste bud cells. However, it is poorly understood how CALHM1/3 is regulated. Biochemical analyses of the two subunits following site-directed mutagenesis and pharmacological treatments established that both CALHM1 and 3 were N-glycosylated at single Asn residues in their second extracellular loops. Biochemical and electrophysiological studies revealed that N-glycan acquisition on CALHM1 and 3, respectively, controls the biosynthesis and gating kinetics of the CALHM1/3 channel. Furthermore, failure in subsequent remodeling of N-glycans decelerated the gating kinetics. Thus, the acquisition of N-glycans on both subunits and their remodeling differentially contribute to the functional expression of CALHM1/3. Meanwhile, metabolic labeling and acyl-biotin exchange assays combined with genetic modification demonstrated that CALHM3 was reversibly palmitoylated at three intracellular Cys residues. Screening of the DHHC protein acyltransferases identified DHHC3 and 15 as CALHM3 palmitoylating enzymes. The palmitoylation-deficient mutant CALHM3 showed a normal degradation rate and interaction with CALHM1. However, the same mutation markedly attenuated the channel activity but not surface localization of CALHM1/3, suggesting that CALHM3 palmitoylation is a critical determinant of CALHM1/3 activity but not its formation or forward trafficking. Overall, this study characterized N-glycosylation and S-palmitoylation of CALHM1/3 subunits and clarified their differential contributions to its functional expression, providing insights into the fine control of the CALHM1/3 channel and associated physiological processes.
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Affiliation(s)
- Motoki Okui
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Department of Dental Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Tatsuro Murakami
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Hongxin Sun
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Chiaki Ikeshita
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Narisato Kanamura
- Department of Dental Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Akiyuki Taruno
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Japan Science and Technology Agency, PRESTO, Kawaguchi, Japan
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8
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Wang X, Xiao Q, Zhu Y, Qi H, Qu D, Yao Y, Jia Y, Guo J, Cheng J, Ji Y, Li G, Tao J. Glycosylation of β1 subunit plays a pivotal role in the toxin sensitivity and activation of BK channels. J Venom Anim Toxins Incl Trop Dis 2021; 27:e20200182. [PMID: 34149831 PMCID: PMC8183112 DOI: 10.1590/1678-9199-jvatitd-2020-0182] [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] [Indexed: 11/22/2022] Open
Abstract
Background: The accessory β1 subunits, regulating the pharmacological and biophysical properties of BK channels, always undergo post-translational modifications, especially glycosylation. To date, it remains elusive whether the glycosylation contributes to the regulation of BK channels by β1 subunits. Methods: Herein, we combined the electrophysiological approach with molecular mutations and biochemical manipulation to investigate the function roles of N-glycosylation in β1 subunits. Results: The results show that deglycosylation of β1 subunits through double-site mutations (β1 N80A/N142A or β1 N80Q/N142Q) could significantly increase the inhibitory potency of iberiotoxin, a specific BK channel blocker. The deglycosylated channels also have a different sensitivity to martentoxin, another BK channel modulator with some remarkable effects as reported before. On the contrary to enhancing effects of martentoxin on glycosylated BK channels under the presence of cytoplasmic Ca2+, deglycosylated channels were not affected by the toxin. However, the deglycosylated channels were surprisingly inhibited by martentoxin under the absence of cytoplasmic Ca2+, while the glycosylated channels were not inhibited under this same condition. In addition, wild type BK (α+β1) channels treated with PNGase F also showed the same trend of pharmacological results to the mutants. Similar to this modulation of glycosylation on BK channel pharmacology, the deglycosylated forms of the channels were activated at a faster speed than the glycosylated ones. However, the V1/2 and slope were not changed by the glycosylation. Conclusion: The present study reveals that glycosylation is an indispensable determinant of the modulation of β1-subunit on BK channel pharmacology and its activation. The loss of glycosylation of β1 subunits could lead to the dysfunction of BK channel, resulting in a pathological state.
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Affiliation(s)
- Xiaoli Wang
- Institute of Biomembrane and Biopharmaceutics, Shanghai University, Shanghai, China
| | - Qian Xiao
- Department of Neurology and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yudan Zhu
- Department of Neurology and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Hong Qi
- Institute of Biomembrane and Biopharmaceutics, Shanghai University, Shanghai, China
| | - Dongxiao Qu
- Department of Neurology and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yu Yao
- Institute of Biomembrane and Biopharmaceutics, Shanghai University, Shanghai, China
| | - Yuxiang Jia
- Institute of Biomembrane and Biopharmaceutics, Shanghai University, Shanghai, China
| | - Jingkan Guo
- Institute of Biomembrane and Biopharmaceutics, Shanghai University, Shanghai, China.,Xinhua Translational Institute for Cancer Pain, Shanghai, China
| | - Jiwei Cheng
- Department of Neurology and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.,Putuo Clinical Medical School, Anhui Medical University, Shanghai, China
| | - Yonghua Ji
- Institute of Biomembrane and Biopharmaceutics, Shanghai University, Shanghai, China.,Xinhua Translational Institute for Cancer Pain, Shanghai, China
| | - Guoyi Li
- Department of Neurology and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.,Putuo Clinical Medical School, Anhui Medical University, Shanghai, China
| | - Jie Tao
- Department of Neurology and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.,Putuo Clinical Medical School, Anhui Medical University, Shanghai, China
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9
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Borgström A, Peinelt C, Stokłosa P. TRPM4 in Cancer-A New Potential Drug Target. Biomolecules 2021; 11:biom11020229. [PMID: 33562811 PMCID: PMC7914809 DOI: 10.3390/biom11020229] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/22/2021] [Accepted: 01/28/2021] [Indexed: 12/11/2022] Open
Abstract
Transient receptor potential melastatin 4 (TRPM4) is widely expressed in various organs and associated with cardiovascular and immune diseases. Lately, the interest in studies on TRPM4 in cancer has increased. Thus far, TRPM4 has been investigated in diffuse large B-cell lymphoma, prostate, colorectal, liver, breast, urinary bladder, cervical, and endometrial cancer. In several types of cancer TRPM4 is overexpressed and contributes to cancer hallmark functions such as increased proliferation and migration and cell cycle shift. Hence, TRPM4 is a potential prognostic cancer marker and a promising anticancer drug target candidate. Currently, the underlying mechanism by which TRPM4 contributes to cancer hallmark functions is under investigation. TRPM4 is a Ca2+-activated monovalent cation channel, and its ion conductivity can decrease intracellular Ca2+ signaling. Furthermore, TRPM4 can interact with different partner proteins. However, the lack of potent and specific TRPM4 inhibitors has delayed the investigations of TRPM4. In this review, we summarize the potential mechanisms of action and discuss new small molecule TRPM4 inhibitors, as well as the TRPM4 antibody, M4P. Additionally, we provide an overview of TRPM4 in human cancer and discuss TRPM4 as a diagnostic marker and anticancer drug target.
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10
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Capera J, Serrano-Novillo C, Navarro-Pérez M, Cassinelli S, Felipe A. The Potassium Channel Odyssey: Mechanisms of Traffic and Membrane Arrangement. Int J Mol Sci 2019; 20:ijms20030734. [PMID: 30744118 PMCID: PMC6386995 DOI: 10.3390/ijms20030734] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/06/2019] [Accepted: 02/08/2019] [Indexed: 12/29/2022] Open
Abstract
Ion channels are transmembrane proteins that conduct specific ions across biological membranes. Ion channels are present at the onset of many cellular processes, and their malfunction triggers severe pathologies. Potassium channels (KChs) share a highly conserved signature that is necessary to conduct K⁺ through the pore region. To be functional, KChs require an exquisite regulation of their subcellular location and abundance. A wide repertoire of signatures facilitates the proper targeting of the channel, fine-tuning the balance that determines traffic and location. These signature motifs can be part of the secondary or tertiary structure of the protein and are spread throughout the entire sequence. Furthermore, the association of the pore-forming subunits with different ancillary proteins forms functional complexes. These partners can modulate traffic and activity by adding their own signatures as well as by exposing or masking the existing ones. Post-translational modifications (PTMs) add a further dimension to traffic regulation. Therefore, the fate of a KCh is not fully dependent on a gene sequence but on the balance of many other factors regulating traffic. In this review, we assemble recent evidence contributing to our understanding of the spatial expression of KChs in mammalian cells. We compile specific signatures, PTMs, and associations that govern the destination of a functional channel.
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Affiliation(s)
- Jesusa Capera
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - Clara Serrano-Novillo
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - María Navarro-Pérez
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - Silvia Cassinelli
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - Antonio Felipe
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
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11
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Long-term 4-AP treatment facilitates functional expression of human Kv1.5 channel. Eur J Pharmacol 2019; 844:195-203. [PMID: 30552904 DOI: 10.1016/j.ejphar.2018.12.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 12/08/2018] [Accepted: 12/11/2018] [Indexed: 11/23/2022]
Abstract
The human Kv1.5 channel (hKv1.5) produces the ultrarapid delayed rectifier potassium current (IKur), which is important for determining the repolarization of action potential in the cardiac atrium. However, the expression of IKur is reduced in patients with chronic atrial fibrillation. 4-Aminopyridine (4-AP) can specifically suppress IKur, suggesting that it modifies hKv1.5 as a chaperone molecule. Herein, the effects of long-term 4-AP treatment on hKv1.5 protein expression and function were investigated in HEK cells. 4-AP treatment (24 h) improved hKv1.5 protein levels, promoted hKv1.5 glycosylation, and facilitated the hKv1.5 current in a time-dependent manner. Long-term 4-AP treatment also markedly enhanced hKv1.5 localization in the cell membrane, endoplasmic reticulum, and Golgi. Importantly, the Ile508 residue located in the hKv1.5 channel pore was found to be important for 4-AP inhibitory activity. These results provide insight into developing hKv1.5 channel blocker that can functionally rescue IKur in patients with chronic atrial fibrillation.
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Cao XJ, Oertel D. Genetic perturbations suggest a role of the resting potential in regulating the expression of the ion channels of the KCNA and HCN families in octopus cells of the ventral cochlear nucleus. Hear Res 2017; 345:57-68. [PMID: 28065805 DOI: 10.1016/j.heares.2017.01.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 01/02/2017] [Accepted: 01/03/2017] [Indexed: 10/20/2022]
Abstract
Low-voltage-activated K+ (gKL) and hyperpolarization-activated mixed cation conductances (gh) mediate currents, IKL and Ih, through channels of the Kv1 (KCNA) and HCN families respectively and give auditory neurons the temporal precision required for signaling information about the onset, fine structure, and time of arrival of sounds. Being partially activated at rest, gKL and gh contribute to the resting potential and shape responses to even small subthreshold synaptic currents. Resting gKL and gh also affect the coupling of somatic depolarization with the generation of action potentials. To learn how these important conductances are regulated we have investigated how genetic perturbations affect their expression in octopus cells of the ventral cochlear nucleus (VCN). We report five new findings: First, the magnitude of gh and gKL varied over more than two-fold between wild type strains of mice. Second, average resting potentials are not different in different strains of mice even in the face of large differences in average gKL and gh. Third, IKL has two components, one being α-dendrotoxin (α-DTX)-sensitive and partially inactivating and the other being α-DTX-insensitive, tetraethylammonium (TEA)-sensitive, and non-inactivating. Fourth, the loss of Kv1.1 results in diminution of the α-DTX-sensitive IKL, and compensatory increased expression of an α-DTX-insensitive, tetraethylammonium (TEA)-sensitive IKL. Fifth, Ih and IKL are balanced at the resting potential in all wild type and mutant octopus cells even when resting potentials vary in individual cells over nearly 10 mV, indicating that the resting potential influences the expression of gh and gKL. The independence of resting potentials on gKL and gh shows that gKL and gh do not, over days or weeks, determine the resting potential but rather that the resting potential plays a role in regulating the magnitude of either or both gKL and gh.
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Affiliation(s)
- Xiao-Jie Cao
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53705, USA
| | - Donata Oertel
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53705, USA.
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