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Parikh A, Krogman W, Walker J. The impact of volatile anesthetics and propofol on phosphatidylinositol 4,5-bisphosphate signaling. Arch Biochem Biophys 2024; 757:110045. [PMID: 38801966 DOI: 10.1016/j.abb.2024.110045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 04/29/2024] [Accepted: 05/24/2024] [Indexed: 05/29/2024]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PIP2), as well as other anionic phospholipids, play a pivotal role in various cellular processes, including ion channel regulation, receptor trafficking, and intracellular signaling pathways. The binding of volatile anesthetics and propofol to PIP2 leads to alterations in PIP2-mediated signaling causing modulation of ion channels such as ɣ-aminobutyric acid type A (GABAA) receptors, voltage-gated calcium channels, and potassium channels through various mechanisms. Additionally, the interaction between anionic phospholipids and G protein-coupled receptors plays a critical role in various anesthetic pathways, with these anesthetic-induced changes impacting PIP2 levels which cause cascading effects on receptor trafficking, including GABAA receptor internalization. This comprehensive review of various mechanisms of interaction provides insights into the intricate interplay between PIP2 signaling and anesthetic-induced changes, shedding light on the molecular mechanisms underlying anesthesia.
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Affiliation(s)
- Ayaan Parikh
- Wichita Collegiate School, Wichita, KS. 9115 E 13th St N, Wichita, KS, 67206, USA.
| | - William Krogman
- University of Kansas School of Medicine-Wichita, Wichita, KS, USA; Department of Anesthesiology, 929 N St Francis, Room 8079, Wichita, KS, 67214, USA
| | - James Walker
- University of Kansas School of Medicine-Wichita, Wichita, KS, USA; Department of Anesthesiology, 929 N St Francis, Room 8079, Wichita, KS, 67214, USA
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2
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Contreras E, Bhoi JD, Sonoda T, Birnbaumer L, Schmidt TM. Melanopsin activates divergent phototransduction pathways in intrinsically photosensitive retinal ganglion cell subtypes. eLife 2023; 12:e80749. [PMID: 37937828 PMCID: PMC10712949 DOI: 10.7554/elife.80749] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 11/06/2023] [Indexed: 11/09/2023] Open
Abstract
Melanopsin signaling within intrinsically photosensitive retinal ganglion cell (ipRGC) subtypes impacts a broad range of behaviors from circadian photoentrainment to conscious visual perception. Yet, how melanopsin phototransduction within M1-M6 ipRGC subtypes impacts cellular signaling to drive diverse behaviors is still largely unresolved. The identity of the phototransduction channels in each subtype is key to understanding this central question but has remained controversial. In this study, we resolve two opposing models of M4 phototransduction, demonstrating that hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are dispensable for this process and providing support for a pathway involving melanopsin-dependent potassium channel closure and canonical transient receptor potential (TRPC) channel opening. Surprisingly, we find that HCN channels are likewise dispensable for M2 phototransduction, contradicting the current model. We instead show that M2 phototransduction requires TRPC channels in conjunction with T-type voltage-gated calcium channels, identifying a novel melanopsin phototransduction target. Collectively, this work resolves key discrepancies in our understanding of ipRGC phototransduction pathways in multiple subtypes and adds to mounting evidence that ipRGC subtypes employ diverse phototransduction cascades to fine-tune cellular responses for downstream behaviors.
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Affiliation(s)
- Ely Contreras
- Department of Neurobiology, Northwestern UniversityEvanstonUnited States
- Northwestern University Interdisciplinary Biological Sciences Program, Northwestern UniversityEvanstonUnited States
| | - Jacob D Bhoi
- Department of Neurobiology, Northwestern UniversityEvanstonUnited States
- Northwestern University Interdepartmental Neuroscience Program, Northwestern UniversityChicagoUnited States
| | - Takuma Sonoda
- Department of Neurobiology, Northwestern UniversityEvanstonUnited States
- Northwestern University Interdepartmental Neuroscience Program, Northwestern UniversityChicagoUnited States
| | - Lutz Birnbaumer
- Laboratory of Signal Transduction, National Institute of Environmental Health SciencesDurhamUnited States
- Institute of Biomedical Research (BIOMED), Catholic University of ArgentinaBuenos AiresArgentina
| | - Tiffany M Schmidt
- Department of Neurobiology, Northwestern UniversityEvanstonUnited States
- Department of Ophthalmology, Feinberg School of MedicineChicagoUnited States
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3
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Lee H, Cho S, Kim MJ, Park YJ, Cho E, Jo YS, Kim YS, Lee JY, Thoudam T, Woo SH, Lee SI, Jeon J, Lee YS, Suh BC, Yoon JH, Go Y, Lee IK, Seo J. ApoE4-dependent lysosomal cholesterol accumulation impairs mitochondrial homeostasis and oxidative phosphorylation in human astrocytes. Cell Rep 2023; 42:113183. [PMID: 37777962 DOI: 10.1016/j.celrep.2023.113183] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 08/07/2023] [Accepted: 09/13/2023] [Indexed: 10/03/2023] Open
Abstract
Recent developments in genome sequencing have expanded the knowledge of genetic factors associated with late-onset Alzheimer's disease (AD). Among them, genetic variant ε4 of the APOE gene (APOE4) confers the greatest disease risk. Dysregulated glucose metabolism is an early pathological feature of AD. Using isogenic ApoE3 and ApoE4 astrocytes derived from human induced pluripotent stem cells, we find that ApoE4 increases glycolytic activity but impairs mitochondrial respiration in astrocytes. Ultrastructural and autophagy flux analyses show that ApoE4-induced cholesterol accumulation impairs lysosome-dependent removal of damaged mitochondria. Acute treatment with cholesterol-depleting agents restores autophagic activity, mitochondrial dynamics, and associated proteomes, and extended treatment rescues mitochondrial respiration in ApoE4 astrocytes. Taken together, our study provides a direct link between ApoE4-induced lysosomal cholesterol accumulation and abnormal oxidative phosphorylation.
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Affiliation(s)
- Hyein Lee
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science & Technology, Daegu 42988, South Korea
| | - Sukhee Cho
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science & Technology, Daegu 42988, South Korea
| | - Mi-Jin Kim
- Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu 41944, South Korea
| | - Yeo Jin Park
- Korean Medicine Life Science, University of Science and Technology, Daejeon 34054, South Korea; Korean Medicine-Application Center, Korea Institute of Oriental Medicine, Daegu 41062, South Korea
| | - Eunji Cho
- Neurodegenerative Disease Research Group, Korea Brain Research Institute, Daegu 41062, South Korea
| | - Yeon Suk Jo
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science & Technology, Daegu 42988, South Korea; Neurodegenerative Disease Research Group, Korea Brain Research Institute, Daegu 41062, South Korea
| | - Yong-Seok Kim
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science & Technology, Daegu 42988, South Korea
| | - Jung Yi Lee
- Leading-Edge Research Center for Drug Discovery and Development for Diabetes and Metabolic Disease, Kyungpook National University School of Medicine, Daegu 41944, South Korea
| | - Themis Thoudam
- Research Institute of Aging and Metabolism, Kyungpook National University School of Medicine, Daegu 41944, South Korea
| | - Seung-Hwa Woo
- Department of New Biology, Daegu Gyeongbuk Institute of Science & Technology, Daegu 42988, South Korea
| | - Se-In Lee
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science & Technology, Daegu 42988, South Korea
| | - Juyeong Jeon
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science & Technology, Daegu 42988, South Korea
| | - Young-Sam Lee
- Department of New Biology, Daegu Gyeongbuk Institute of Science & Technology, Daegu 42988, South Korea
| | - Byung-Chang Suh
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science & Technology, Daegu 42988, South Korea
| | - Jong Hyuk Yoon
- Neurodegenerative Disease Research Group, Korea Brain Research Institute, Daegu 41062, South Korea
| | - Younghoon Go
- Korean Medicine-Application Center, Korea Institute of Oriental Medicine, Daegu 41062, South Korea.
| | - In-Kyu Lee
- Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu 41944, South Korea; Leading-Edge Research Center for Drug Discovery and Development for Diabetes and Metabolic Disease, Kyungpook National University School of Medicine, Daegu 41944, South Korea; Research Institute of Aging and Metabolism, Kyungpook National University School of Medicine, Daegu 41944, South Korea.
| | - Jinsoo Seo
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science & Technology, Daegu 42988, South Korea.
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4
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Two-step structural changes in M3 muscarinic receptor activation rely on the coupled G q protein cycle. Nat Commun 2023; 14:1276. [PMID: 36882424 PMCID: PMC9992711 DOI: 10.1038/s41467-023-36911-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 02/23/2023] [Indexed: 03/09/2023] Open
Abstract
G protein-coupled receptors (GPCRs) regulate diverse intracellular signaling pathways through the activation of heterotrimeric G proteins. However, the effects of the sequential activation-deactivation cycle of G protein on the conformational changes of GPCRs remains unknown. By developing a Förster resonance energy transfer (FRET) tool for human M3 muscarinic receptor (hM3R), we find that a single-receptor FRET probe can display the consecutive structural conversion of a receptor by G protein cycle. Our results reveal that the G protein activation evokes a two-step change in the hM3R structure, including the fast step mediated by Gq protein binding and the subsequent slower step mediated by the physical separation of the Gαq and Gβγ subunits. We also find that the separated Gαq-GTP forms a stable complex with the ligand-activated hM3R and phospholipase Cβ. In sum, the present study uncovers the real-time conformational dynamics of innate hM3R during the downstream Gq protein cycle.
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5
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Park CG, Yu W, Suh BC. Molecular basis of the PIP2-dependent regulation of CaV2.2 channel and its modulation by CaV β subunits. eLife 2022; 11:69500. [DOI: 10.7554/elife.69500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 10/25/2022] [Indexed: 11/13/2022] Open
Abstract
High-voltage-activated Ca2+ (CaV) channels that adjust Ca2+ influx upon membrane depolarization are differentially regulated by phosphatidylinositol 4,5-bisphosphate (PIP2) in an auxiliary CaV β subunit-dependent manner. However, the molecular mechanism by which the β subunits control the PIP2 sensitivity of CaV channels remains unclear. By engineering various α1B and β constructs in tsA-201 cells, we reported that at least two PIP2-binding sites, including the polybasic residues at the C-terminal end of I–II loop and the binding pocket in S4II domain, exist in the CaV2.2 channels. Moreover, they were distinctly engaged in the regulation of channel gating depending on the coupled CaV β2 subunits. The membrane-anchored β subunit abolished the PIP2 interaction of the phospholipid-binding site in the I–II loop, leading to lower PIP2 sensitivity of CaV2.2 channels. By contrast, PIP2 interacted with the basic residues in the S4II domain of CaV2.2 channels regardless of β2 isotype. Our data demonstrated that the anchoring properties of CaV β2 subunits to the plasma membrane determine the biophysical states of CaV2.2 channels by regulating PIP2 coupling to the nonspecific phospholipid-binding site in the I–II loop.
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Affiliation(s)
- Cheon-Gyu Park
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST)
| | - Wookyung Yu
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST)
| | - Byung-Chang Suh
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST)
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6
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Zhao Z, Li S, Pan Y, Jiang P, Dong Y, Yang H, Wang X, Guan X, Zhou Z. Proteomics reveals gender differences in physiological characteristics of the gonads and tube feet of the sea cucumber, Apostichopus japonicus. J Proteomics 2022; 251:104396. [PMID: 34673268 DOI: 10.1016/j.jprot.2021.104396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 04/29/2021] [Accepted: 09/27/2021] [Indexed: 11/29/2022]
Abstract
The sea cucumber Apostichopus japonicus is an important aquaculture species in China because of its high nutritional and medicinal values. Gender, as a factor affecting the physiology of organisms, is always considered when improving the breeding efficiency of economically important animals. In the present study, protein expression profiles of the gonads and tube feet of male and female A. japonicus were investigated using a comparative proteomics approach. A set of 7499 proteins were identified, which covered a broad range of functions based on function annotations. A significant difference in protein expression profiles was observed between the gonads and tube feet of A. japonicus; gonads showed more apparent gender differences than tube feet. Moreover, the findings revealed that male A. japonicus had more specific functions and most of these functions were associated with energy consumption. Further analyses suggested that the regulation of ERK activity and the capacity of tyrosine production and virus immunity might be more powerful in male and female A. japonicus, respectively. Some candidate proteins were also recognized as potential targets for gender identification of A. japonicus. Overall, our study provides new insights into the understanding of molecular mechanisms underlying gender-based physiological differences in A. japonicus. SIGNIFICANCE: The current study aimed to reveal gender differences in the physiological characteristics of gonads and tube feet of the sea cucumber A. japonicus. To the best of our knowledge, this is the first proteomics study to analyze the differences in the protein expression profiles of external organs between male and female A. japonicus. The analysis revealed gender differences in the protein expression profiles of both gonads and tube feet of A. japonicus, and the gender differences in gonads were quite apparent. Moreover, according to the recognition of differentially expressed proteins and the enrichment analyses based on Kyoto Encyclopedia of Genes and Genomes, a draft view of how the physiological functions of A. japonicus were affected by gender was obtained. Male A. japonicus could have more specific functions related to energy consumption than females. The regulation of ERK activity and virus immunity might be more robust in male and female A. japonicus, respectively. Some candidate proteins were also recognized as potential targets for gender identification of A. japonicus. The findings presented here will improve the understanding of researchers about the molecular mechanisms underlying gender-based differences in A. japonicus and contribute to the meticulous breeding of A. japonicus.
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Affiliation(s)
- Zelong Zhao
- Liaoning Key Lab of Germplasm Improvement and Fine Seed Breeding of Marine Aquatic animals, Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning 116023, PR China
| | - Shilei Li
- Liaoning Key Lab of Germplasm Improvement and Fine Seed Breeding of Marine Aquatic animals, Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning 116023, PR China
| | - Yongjia Pan
- Liaoning Key Lab of Germplasm Improvement and Fine Seed Breeding of Marine Aquatic animals, Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning 116023, PR China
| | - Pingzhe Jiang
- Liaoning Key Lab of Germplasm Improvement and Fine Seed Breeding of Marine Aquatic animals, Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning 116023, PR China
| | - Ying Dong
- Liaoning Key Lab of Germplasm Improvement and Fine Seed Breeding of Marine Aquatic animals, Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning 116023, PR China
| | - Huihua Yang
- Liaoning Key Lab of Germplasm Improvement and Fine Seed Breeding of Marine Aquatic animals, Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning 116023, PR China
| | - Xuda Wang
- Liaoning Key Lab of Germplasm Improvement and Fine Seed Breeding of Marine Aquatic animals, Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning 116023, PR China
| | - Xiaoyan Guan
- Liaoning Key Lab of Germplasm Improvement and Fine Seed Breeding of Marine Aquatic animals, Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning 116023, PR China
| | - Zunchun Zhou
- Liaoning Key Lab of Germplasm Improvement and Fine Seed Breeding of Marine Aquatic animals, Liaoning Ocean and Fisheries Science Research Institute, Dalian, Liaoning 116023, PR China.
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7
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Dong Y, Gao Y, Xu S, Wang Y, Yu Z, Li Y, Li B, Yuan T, Yang B, Zhang XC, Jiang D, Huang Z, Zhao Y. Closed-state inactivation and pore-blocker modulation mechanisms of human Ca V2.2. Cell Rep 2021; 37:109931. [PMID: 34731621 DOI: 10.1016/j.celrep.2021.109931] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 09/13/2021] [Accepted: 10/11/2021] [Indexed: 11/19/2022] Open
Abstract
N-type voltage-gated calcium (CaV) channels mediate Ca2+ influx at presynaptic terminals in response to action potentials and play vital roles in synaptogenesis, release of neurotransmitters, and nociceptive transmission. Here, we elucidate a cryo-electron microscopy (cryo-EM) structure of the human CaV2.2 complex in apo, ziconotide-bound, and two CaV2.2-specific pore blockers-bound states. The second voltage-sensing domain (VSD) is captured in a resting-state conformation, trapped by a phosphatidylinositol 4,5-bisphosphate (PIP2) molecule, which is distinct from the other three VSDs of CaV2.2, as well as activated VSDs observed in previous structures of CaV channels. This structure reveals the molecular basis for the unique inactivation process of CaV2.2 channels, in which the intracellular gate formed by S6 helices is closed and a W-helix from the domain II-III linker stabilizes closed-state inactivation. The structures of this inactivated, drug-bound complex lay a solid foundation for developing new state-dependent blockers for treatment of chronic pain.
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Affiliation(s)
- Yanli Dong
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yiwei Gao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shuai Xu
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Yuhang Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhuoya Yu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yue Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bin Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tian Yuan
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Bei Yang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xuejun Cai Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Daohua Jiang
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
| | - Zhuo Huang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China; IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China.
| | - Yan Zhao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
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8
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Kim KW, Suh BC. Ethanol inhibits Kv7.2/7.3 channel open probability by reducing the PI(4,5)P2 sensitivity of Kv7.2 subunit. BMB Rep 2021. [PMID: 33408002 PMCID: PMC8249878 DOI: 10.5483/bmbrep.2021.54.6.231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Ethanol often causes critical health problems by altering the neuro-nal activities of the central and peripheral nerve systems. One of the cellular targets of ethanol is the plasma membrane proteins including ion channels and receptors. Recently, we reported that ethanol elevates membrane excitability in sympathetic neurons by inhibiting Kv7.2/7.3 channels in a cell type-specific manner. Even though our studies revealed that the inhibitory effects of ethanol on the Kv7.2/7.3 channel was diminished by the increase of plasma membrane phosphatidylinositol 4,5-bisphosphate (PI (4,5)P2), the molecular mechanism of ethanol on Kv7.2/7.3 channel inhibition remains unclear. By investigating the kinetics of Kv7.2/7.3 current in high K+ solution, we found that ethanol inhibited Kv7.2/7.3 channels through a mechanism distinct from that of tetraethylammonium (TEA) which enters into the pore and blocks the gate of the channels. Using a non-stationary noise analysis (NSNA), we demonstrated that the inhibitory effect of ethanol is the result of reduction of open probability (PO) of the Kv7.2/7.3 channel, but not of a single channel current (i) or channel number (N). Finally, ethanol selectively facilitated the kinetics of Kv7.2 current suppression by voltage-sensing phosphatase (VSP)-induced PI(4,5)P2 depletion, while it slowed down Kv7.2 current recovery from the VSP-induced inhibition. Together our results suggest that ethanol regulates neuronal activity through the reduction of open probability and PI(4,5)P2 sensitivity of Kv7.2/7.3 channels.
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Affiliation(s)
- Kwon-Woo Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Byung-Chang Suh
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
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9
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Chamberlain LH, Shipston MJ, Gould GW. Regulatory effects of protein S-acylation on insulin secretion and insulin action. Open Biol 2021; 11:210017. [PMID: 33784857 PMCID: PMC8061761 DOI: 10.1098/rsob.210017] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Post-translational modifications (PTMs) such as phosphorylation and ubiquitination are well-studied events with a recognized importance in all aspects of cellular function. By contrast, protein S-acylation, although a widespread PTM with important functions in most physiological systems, has received far less attention. Perturbations in S-acylation are linked to various disorders, including intellectual disability, cancer and diabetes, suggesting that this less-studied modification is likely to be of considerable biological importance. As an exemplar, in this review, we focus on the newly emerging links between S-acylation and the hormone insulin. Specifically, we examine how S-acylation regulates key components of the insulin secretion and insulin response pathways. The proteins discussed highlight the diverse array of proteins that are modified by S-acylation, including channels, transporters, receptors and trafficking proteins and also illustrate the diverse effects that S-acylation has on these proteins, from membrane binding and micro-localization to regulation of protein sorting and protein interactions.
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Affiliation(s)
- Luke H Chamberlain
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Michael J Shipston
- Centre for Discovery Brain Sciences, Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Gwyn W Gould
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
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10
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Ko W, Jung SR, Kim KW, Yeon JH, Park CG, Nam JH, Hille B, Suh BC. Allosteric modulation of alternatively spliced Ca 2+-activated Cl - channels TMEM16A by PI(4,5)P 2 and CaMKII. Proc Natl Acad Sci U S A 2020; 117:30787-30798. [PMID: 33199590 PMCID: PMC7720229 DOI: 10.1073/pnas.2014520117] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Transmembrane 16A (TMEM16A, anoctamin1), 1 of 10 TMEM16 family proteins, is a Cl- channel activated by intracellular Ca2+ and membrane voltage. This channel is also regulated by the membrane phospholipid phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. We find that two splice variants of TMEM16A show different sensitivity to endogenous PI(4,5)P2 degradation, where TMEM16A(ac) displays higher channel activity and more current inhibition by PI(4,5)P2 depletion than TMEM16A(a). These two channel isoforms differ in the alternative splicing of the c-segment (exon 13). The current amplitude and PI(4,5)P2 sensitivity of both TMEM16A(ac) and (a) are significantly strengthened by decreased free cytosolic ATP and by conditions that decrease phosphorylation by Ca2+/calmodulin-dependent protein kinase II (CaMKII). Noise analysis suggests that the augmentation of currents is due to a rise of single-channel current (i), but not of channel number (N) or open probability (PO). Mutagenesis points to arginine 486 in the first intracellular loop as a putative binding site for PI(4,5)P2, and to serine 673 in the third intracellular loop as a site for regulatory channel phosphorylation that modulates the action of PI(4,5)P2 In silico simulation suggests how phosphorylation of S673 allosterically and differently changes the structure of the distant PI(4,5)P2-binding site between channel splice variants with and without the c-segment exon. In sum, our study reveals the following: differential regulation of alternatively spliced TMEM16A(ac) and (a) by plasma membrane PI(4,5)P2, modification of these effects by channel phosphorylation, identification of the molecular sites, and mechanistic explanation by in silico simulation.
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Affiliation(s)
- Woori Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea
| | - Seung-Ryoung Jung
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Kwon-Woo Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea
| | - Jun-Hee Yeon
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea
| | - Cheon-Gyu Park
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea
| | - Joo Hyun Nam
- Department of Physiology, College of Medicine, Dongguk University, Gyeongju 38066, Republic of Korea
- Ion Channel Disease Research Center, College of Medicine, Dongguk University, Goyang, Gyeonggi-do 10326, Republic of Korea
| | - Bertil Hille
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Byung-Chang Suh
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea;
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11
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Castro H, Bermeo K, Arenas I, Garcia DE. Maintenance of Ca V2.2 channel-current by PIP 2 unveiled by neomycin in sympathetic neurons of the rat. Arch Biochem Biophys 2020; 682:108261. [PMID: 31923392 DOI: 10.1016/j.abb.2020.108261] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Revised: 12/13/2019] [Accepted: 01/06/2020] [Indexed: 02/01/2023]
Abstract
Membrane lipids are key determinants in the regulation of voltage-gated ion channels. Phosphatidylinositol 4,5-bisphosphate (PIP2), a native membrane phospholipid, has been involved in the maintenance of the current amplitude and in the voltage-independent regulation of voltage-gated calcium channels (VGCC). However, the nature of the PIP2 regulation on VGCC has not been fully elucidated. This work aimed to investigate whether the interacting PIP2 electrostatic charges may account for maintaining the current amplitude of CaV2.2 channels. Furthermore, we tested whether charge shielding of PIP2 mimics the voltage-independent inhibition induced by M1 muscarinic acetylcholine receptor (M1R) activation. Therefore, neomycin, a polycation that has been shown to block electrostatic interactions of PIP2, was intracellularly dialyzed in superior cervical ganglion (SCG) neurons of the rat. Consistently, neomycin time-dependently diminished the calcium current amplitude letting the channel exhibit the hallmarks of the voltage-independent regulation. These results support that interacting PIP2 charges not only underly the maintenance of the channel-current but also that charge screening of PIP2 by itself unveils the voltage-independent features of CaV2.2 channels in SCG neurons.
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Affiliation(s)
- Hector Castro
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70250, C.P. 04510, CdMx, México
| | - Karina Bermeo
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70250, C.P. 04510, CdMx, México
| | - Isabel Arenas
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70250, C.P. 04510, CdMx, México
| | - David E Garcia
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70250, C.P. 04510, CdMx, México.
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12
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Malloy CA, Somasundaram E, Omar A, Bhutto U, Medley M, Dzubuk N, Cooper RL. Pharmacological identification of cholinergic receptor subtypes: modulation of locomotion and neural circuit excitability in Drosophila larvae. Neuroscience 2019; 411:47-64. [DOI: 10.1016/j.neuroscience.2019.05.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 04/16/2019] [Accepted: 05/07/2019] [Indexed: 01/28/2023]
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Bielopolski N, Amin H, Apostolopoulou AA, Rozenfeld E, Lerner H, Huetteroth W, Lin AC, Parnas M. Inhibitory muscarinic acetylcholine receptors enhance aversive olfactory learning in adult Drosophila. eLife 2019; 8:48264. [PMID: 31215865 PMCID: PMC6641838 DOI: 10.7554/elife.48264] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 06/18/2019] [Indexed: 11/13/2022] Open
Abstract
Olfactory associative learning in Drosophila is mediated by synaptic plasticity between the Kenyon cells of the mushroom body and their output neurons. Both Kenyon cells and their inputs from projection neurons are cholinergic, yet little is known about the physiological function of muscarinic acetylcholine receptors in learning in adult flies. Here, we show that aversive olfactory learning in adult flies requires type A muscarinic acetylcholine receptors (mAChR-A), particularly in the gamma subtype of Kenyon cells. mAChR-A inhibits odor responses and is localized in Kenyon cell dendrites. Moreover, mAChR-A knockdown impairs the learning-associated depression of odor responses in a mushroom body output neuron. Our results suggest that mAChR-A function in Kenyon cell dendrites is required for synaptic plasticity between Kenyon cells and their output neurons.
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Affiliation(s)
- Noa Bielopolski
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Hoger Amin
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom
| | | | - Eyal Rozenfeld
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Hadas Lerner
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Wolf Huetteroth
- Institute for Biology, University of Leipzig, Leipzig, Germany
| | - Andrew C Lin
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom
| | - Moshe Parnas
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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Mallmann R, Ondacova K, Moravcikova L, Jurkovicova-Tarabova B, Pavlovicova M, Moravcik R, Lichvarova L, Kominkova V, Klugbauer N, Lacinova L. Four novel interaction partners demonstrate diverse modulatory effects on voltage-gated Ca V2.2 Ca 2+ channels. Pflugers Arch 2019; 471:861-874. [PMID: 30612149 DOI: 10.1007/s00424-018-02248-x] [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: 05/30/2018] [Revised: 12/14/2018] [Accepted: 12/18/2018] [Indexed: 12/11/2022]
Abstract
Voltage-gated Ca2+ channels are embedded in a network of protein interactions that are fundamental for channel function and modulation. Different strategies such as high-resolution quantitative MS analyses and yeast-two hybrid screens have been used to uncover these Ca2+ channel nanodomains. We applied the yeast split-ubiquitin system with its specific advantages to search for interaction partners of the CaV2.2 Ca2+ channel and identified four proteins: reticulon 1 (RTN1), member 1 of solute carrier family 38 (SLC38), prostaglandin D2 synthase (PTGDS) and transmembrane protein 223 (TMEM223). Interactions were verified using the yeast split-ubiquitin system and narrowed down to CaV2.2 domain IV. Colocalization studies using fluorescent constructs demonstrated defined regions of subcellular localization. Detailed electrophysiological studies revealed that coexpression of RTN1 modulated CaV2.2 channels only to a minor extent. SLC38 accelerated the cumulative current inactivation during a high-frequency train of brief depolarizing pulses. As neurons expressing CaV2.2 channels were exposed to high-frequency bursts under physiological conditions, observed regulation may have a negative modulatory effect on transmitter release. Coexpression of PTGDS significantly lowered the average current density and slowed the kinetics of cumulative current inactivation. Since the latter effect was not significant, it may only partly compensate the first one under physiological conditions. Expression of TMEM223 lowered the average current density, accelerated the kinetics of cumulative current inactivation and slowed the kinetics of recovery from inactivation. Therefore, TMEM223 and, to a lesser extent, PTGDS, may negatively modulate Ca2+ entry required for transmitter release and/or for dendritic plasticity under physiological conditions.
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Affiliation(s)
- Robert Mallmann
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Fakultät für Medizin, Albert-Ludwigs-Universität Freiburg, Albertstr. 25, 79104, Freiburg, Germany
| | - Katarina Ondacova
- Center of Bioscience, Institute for Molecular Physiology and Genetics, 84005, Bratislava, Slovakia
| | - Lucia Moravcikova
- Center of Bioscience, Institute for Molecular Physiology and Genetics, 84005, Bratislava, Slovakia
| | | | - Michaela Pavlovicova
- Center of Bioscience, Institute for Molecular Physiology and Genetics, 84005, Bratislava, Slovakia
| | - Roman Moravcik
- Center of Bioscience, Institute for Molecular Physiology and Genetics, 84005, Bratislava, Slovakia
| | - Lucia Lichvarova
- Center of Bioscience, Institute for Molecular Physiology and Genetics, 84005, Bratislava, Slovakia
| | - Viera Kominkova
- Center of Bioscience, Institute for Molecular Physiology and Genetics, 84005, Bratislava, Slovakia
| | - Norbert Klugbauer
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Fakultät für Medizin, Albert-Ludwigs-Universität Freiburg, Albertstr. 25, 79104, Freiburg, Germany
| | - Lubica Lacinova
- Center of Bioscience, Institute for Molecular Physiology and Genetics, 84005, Bratislava, Slovakia.
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Okamura Y, Kawanabe A, Kawai T. Voltage-Sensing Phosphatases: Biophysics, Physiology, and Molecular Engineering. Physiol Rev 2019; 98:2097-2131. [PMID: 30067160 DOI: 10.1152/physrev.00056.2017] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Voltage-sensing phosphatase (VSP) contains a voltage sensor domain (VSD) similar to that in voltage-gated ion channels, and a phosphoinositide phosphatase region similar to phosphatase and tensin homolog deleted on chromosome 10 (PTEN). The VSP gene is conserved from unicellular organisms to higher vertebrates. Membrane depolarization induces electrical driven conformational rearrangement in the VSD, which is translated into catalytic enzyme activity. Biophysical and structural characterization has revealed details of the mechanisms underlying the molecular functions of VSP. Coupling between the VSD and the enzyme is tight, such that enzyme activity is tuned in a graded fashion to the membrane voltage. Upon VSP activation, multiple species of phosphoinositides are simultaneously altered, and the profile of enzyme activity depends on the history of the membrane potential. VSPs have been the obvious candidate link between membrane potential and phosphoinositide regulation. However, patterns of voltage change regulating VSP in native cells remain largely unknown. This review addresses the current understanding of the biophysical biochemical properties of VSP and provides new insight into the proposed functions of VSP.
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Affiliation(s)
- Yasushi Okamura
- Department of Physiology, Laboratory of Integrative Physiology, Graduate School of Medicine, Osaka University , Osaka , Japan ; and Graduate School of Frontier Biosciences, Osaka University , Osaka , Japan
| | - Akira Kawanabe
- Department of Physiology, Laboratory of Integrative Physiology, Graduate School of Medicine, Osaka University , Osaka , Japan ; and Graduate School of Frontier Biosciences, Osaka University , Osaka , Japan
| | - Takafumi Kawai
- Department of Physiology, Laboratory of Integrative Physiology, Graduate School of Medicine, Osaka University , Osaka , Japan ; and Graduate School of Frontier Biosciences, Osaka University , Osaka , Japan
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Translocatable voltage-gated Ca 2+ channel β subunits in α1-β complexes reveal competitive replacement yet no spontaneous dissociation. Proc Natl Acad Sci U S A 2018; 115:E9934-E9943. [PMID: 30257950 DOI: 10.1073/pnas.1809762115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
β subunits of high voltage-gated Ca2+ (CaV) channels promote cell-surface expression of pore-forming α1 subunits and regulate channel gating through binding to the α-interaction domain (AID) in the first intracellular loop. We addressed the stability of CaV α1B-β interactions by rapamycin-translocatable CaV β subunits that allow drug-induced sequestration and uncoupling of the β subunit from CaV2.2 channel complexes in intact cells. Without CaV α1B/α2δ1, all modified β subunits, except membrane-tethered β2a and β2e, are in the cytosol and rapidly translocate upon rapamycin addition to anchors on target organelles: plasma membrane, mitochondria, or endoplasmic reticulum. In cells coexpressing CaV α1B/α2δ1 subunits, the translocatable β subunits colocalize at the plasma membrane with α1B and stay there after rapamycin application, indicating that interactions between α1B and bound β subunits are very stable. However, the interaction becomes dynamic when other competing β isoforms are coexpressed. Addition of rapamycin, then, switches channel gating and regulation by phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] lipid. Thus, expression of free β isoforms around the channel reveals a dynamic aspect to the α1B-β interaction. On the other hand, translocatable β subunits with AID-binding site mutations are easily dissociated from CaV α1B on the addition of rapamycin, decreasing current amplitude and PI(4,5)P2 sensitivity. Furthermore, the mutations slow CaV2.2 current inactivation and shift the voltage dependence of activation to more positive potentials. Mutated translocatable β subunits work similarly in CaV2.3 channels. In sum, the strong interaction of CaV α1B-β subunits can be overcome by other free β isoforms, permitting dynamic changes in channel properties in intact cells.
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18
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Park CG, Suh BC. The HOOK region of β subunits controls gating of voltage-gated Ca 2+ channels by electrostatically interacting with plasma membrane. Channels (Austin) 2017; 11:467-475. [PMID: 28569643 DOI: 10.1080/19336950.2017.1335841] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Recently, we showed that the HOOK region of the β2 subunit electrostatically interacts with the plasma membrane and regulates the current inactivation and phosphatidylinositol 4,5-bisphosphate (PIP2) sensitivity of voltage-gated Ca2+ (CaV) 2.2 channels. Here, we report that voltage-dependent gating and current density of the CaV2.2 channels are also regulated by the HOOK region of the β2 subunit. The HOOK region can be divided into 3 domains: S (polyserine), A (polyacidic), and B (polybasic). We found that the A domain shifted the voltage-dependent inactivation and activation of CaV2.2 channels to more hyperpolarized and depolarized voltages, respectively, whereas the B domain evoked these responses in the opposite directions. In addition, the A domain decreased the current density of the CaV2.2 channels, while the B domain increased it. Together, our data demonstrate that the flexible HOOK region of the β2 subunit plays an important role in determining the overall CaV channel gating properties.
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Affiliation(s)
- Cheon-Gyu Park
- a Department of Brain and Cognitive Sciences , DGIST , Daegu , South Korea
| | - Byung-Chang Suh
- a Department of Brain and Cognitive Sciences , DGIST , Daegu , South Korea
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19
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Park CG, Park Y, Suh BC. The HOOK region of voltage-gated Ca2+ channel β subunits senses and transmits PIP2 signals to the gate. J Gen Physiol 2017; 149:261-276. [PMID: 28087621 PMCID: PMC5299622 DOI: 10.1085/jgp.201611677] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 12/12/2016] [Accepted: 12/22/2016] [Indexed: 12/12/2022] Open
Abstract
The β subunit of voltage-gated Ca2+ (CaV) channels plays an important role in regulating gating of the α1 pore-forming subunit and its regulation by phosphatidylinositol 4,5-bisphosphate (PIP2). Subcellular localization of the CaV β subunit is critical for this effect; N-terminal-dependent membrane targeting of the β subunit slows inactivation and decreases PIP2 sensitivity. Here, we provide evidence that the HOOK region of the β subunit plays an important role in the regulation of CaV biophysics. Based on amino acid composition, we broadly divide the HOOK region into three domains: S (polyserine), A (polyacidic), and B (polybasic). We show that a β subunit containing only its A domain in the HOOK region increases inactivation kinetics and channel inhibition by PIP2 depletion, whereas a β subunit with only a B domain decreases these responses. When both the A and B domains are deleted, or when the entire HOOK region is deleted, the responses are elevated. Using a peptide-to-liposome binding assay and confocal microscopy, we find that the B domain of the HOOK region directly interacts with anionic phospholipids via polybasic and two hydrophobic Phe residues. The β2c-short subunit, which lacks an A domain and contains fewer basic amino acids and no Phe residues in the B domain, neither associates with phospholipids nor affects channel gating dynamically. Together, our data suggest that the flexible HOOK region of the β subunit acts as an important regulator of CaV channel gating via dynamic electrostatic and hydrophobic interaction with the plasma membrane.
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Affiliation(s)
- Cheon-Gyu Park
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Korea
| | - Yongsoo Park
- Izmir International Biomedicine and Genome Institute (iBG-izmir), Dokuz Eylul University, 35340 Balcova, Izmir, Turkey
| | - Byung-Chang Suh
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Korea
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Kim DI, Kweon HJ, Park Y, Jang DJ, Suh BC. Ca2+ controls gating of voltage-gated calcium channels by releasing the β2e subunit from the plasma membrane. Sci Signal 2016; 9:ra67. [PMID: 27382026 DOI: 10.1126/scisignal.aad7247] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Voltage-gated calcium (Cav) channels, which are regulated by membrane potential, cytosolic Ca(2+), phosphorylation, and membrane phospholipids, govern Ca(2+) entry into excitable cells. Cav channels contain a pore-forming α1 subunit, an auxiliary α2δ subunit, and a regulatory β subunit, each encoded by several genes in mammals. In addition to a domain that interacts with the α1 subunit, β2e and β2a also interact with the cytoplasmic face of the plasma membrane through an electrostatic interaction for β2e and posttranslational acylation for β2a. We found that an increase in cytosolic Ca(2+) promoted the release of β2e from the membrane without requiring substantial depletion of the anionic phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2) from the plasma membrane. Experiments with liposomes indicated that Ca(2+) disrupted the interaction of the β2e amino-terminal peptide with membranes containing PIP2 Ca(2+) binding to calmodulin (CaM) leads to CaM-mediated inactivation of Cav currents. Although Cav2.2 coexpressed with β2a required Ca(2+)-dependent activation of CaM for Ca(2+)-mediated reduction in channel activity, Cav2.2 coexpressed with β2e exhibited Ca(2+)-dependent inactivation of the channel even in the presence of Ca(2+)-insensitive CaM. Inducible depletion of PIP2 reduced Cav2.2 currents, and in cells coexpressing β2e, but not a form that lacks the polybasic region, increased intracellular Ca(2+) further reduced Cav2.2 currents. Many hormone- or neurotransmitter-activated receptors stimulate PIP2 hydrolysis and increase cytosolic Ca(2+); thus, our findings suggest that β2e may integrate such receptor-mediated signals to limit Cav activity.
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Affiliation(s)
- Dong-Il Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Hae-Jin Kweon
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea
| | - Yongsoo Park
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Deok-Jin Jang
- Department of Ecological Science, College of Ecology and Environment, Kyungpook National University, Kyungbuk 742-711, Korea
| | - Byung-Chang Suh
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea.
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Molecular Basis of the Membrane Interaction of the β2e Subunit of Voltage-Gated Ca(2+) Channels. Biophys J 2016; 109:922-35. [PMID: 26331250 DOI: 10.1016/j.bpj.2015.07.040] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 07/27/2015] [Accepted: 07/28/2015] [Indexed: 12/30/2022] Open
Abstract
The auxiliary β subunit plays an important role in the regulation of voltage-gated calcium (CaV) channels. Recently, it was revealed that β2e associates with the plasma membrane through an electrostatic interaction between N-terminal basic residues and anionic phospholipids. However, a molecular-level understanding of β-subunit membrane recruitment in structural detail has remained elusive. In this study, using a combination of site-directed mutagenesis, liposome-binding assays, and multiscale molecular-dynamics (MD) simulation, we developed a physical model of how the β2e subunit is recruited electrostatically to the plasma membrane. In a fluorescence resonance energy transfer assay with liposomes, binding of the N-terminal peptide (23 residues) to liposome was significantly increased in the presence of phosphatidylserine (PS) and phosphatidylinositol 4,5-bisphosphate (PIP2). A mutagenesis analysis suggested that two basic residues proximal to Met-1, Lys-2 (K2) and Trp-5 (W5), are more important for membrane binding of the β2e subunit than distal residues from the N-terminus. Our MD simulations revealed that a stretched binding mode of the N-terminus to PS is required for stable membrane attachment through polar and nonpolar interactions. This mode obtained from MD simulations is consistent with experimental results showing that K2A, W5A, and K2A/W5A mutants failed to be targeted to the plasma membrane. We also investigated the effects of a mutated β2e subunit on inactivation kinetics and regulation of CaV channels by PIP2. In experiments with voltage-sensing phosphatase (VSP), a double mutation in the N-terminus of β2e (K2A/W5A) increased the PIP2 sensitivity of CaV2.2 and CaV1.3 channels by ∼3-fold compared with wild-type β2e subunit. Together, our results suggest that membrane targeting of the β2e subunit is initiated from the nonspecific electrostatic insertion of N-terminal K2 and W5 residues into the membrane. The PS-β2e interaction observed here provides a molecular insight into general principles for protein binding to the plasma membrane, as well as the regulatory roles of phospholipids in transporters and ion channels.
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Phosphoinositide 5- and 3-phosphatase activities of a voltage-sensing phosphatase in living cells show identical voltage dependence. Proc Natl Acad Sci U S A 2016; 113:E3686-95. [PMID: 27222577 DOI: 10.1073/pnas.1606472113] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Voltage-sensing phosphatases (VSPs) are homologs of phosphatase and tensin homolog (PTEN), a phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2] and phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] 3-phosphatase. However, VSPs have a wider range of substrates, cleaving 3-phosphate from PI(3,4)P2 and probably PI(3,4,5)P3 as well as 5-phosphate from phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and PI(3,4,5)P3 in response to membrane depolarization. Recent proposals say these reactions have differing voltage dependence. Using Förster resonance energy transfer probes specific for different PIs in living cells with zebrafish VSP, we quantitate both voltage-dependent 5- and 3-phosphatase subreactions against endogenous substrates. These activities become apparent with different voltage thresholds, voltage sensitivities, and catalytic rates. As an analytical tool, we refine a kinetic model that includes the endogenous pools of phosphoinositides, endogenous phosphatase and kinase reactions connecting them, and four exogenous voltage-dependent 5- and 3-phosphatase subreactions of VSP. We show that apparent voltage threshold differences for seeing effects of the 5- and 3-phosphatase activities in cells are not due to different intrinsic voltage dependence of these reactions. Rather, the reactions have a common voltage dependence, and apparent differences arise only because each VSP subreaction has a different absolute catalytic rate that begins to surpass the respective endogenous enzyme activities at different voltages. For zebrafish VSP, our modeling revealed that 3-phosphatase activity against PI(3,4,5)P3 is 55-fold slower than 5-phosphatase activity against PI(4,5)P2; thus, PI(4,5)P2 generated more slowly from dephosphorylating PI(3,4,5)P3 might never accumulate. When 5-phosphatase activity was counteracted by coexpression of a phosphatidylinositol 4-phosphate 5-kinase, there was accumulation of PI(4,5)P2 in parallel to PI(3,4,5)P3 dephosphorylation, emphasizing that VSPs can cleave the 3-phosphate of PI(3,4,5)P3.
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Jeong JY, Kweon HJ, Suh BC. Dual Regulation of R-Type CaV2.3 Channels by M1 Muscarinic Receptors. Mol Cells 2016; 39:322-9. [PMID: 26923189 PMCID: PMC4844939 DOI: 10.14348/molcells.2016.2292] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 02/03/2016] [Accepted: 02/05/2016] [Indexed: 11/27/2022] Open
Abstract
Voltage-gated Ca(2+) (CaV) channels are dynamically modulated by G protein-coupled receptors (GPCR). The M1 muscarinic receptor stimulation is known to enhance CaV2.3 channel gating through the activation of protein kinase C (PKC). Here, we found that M1 receptors also inhibit CaV2.3 currents when the channels are fully activated by PKC. In whole-cell configuration, the application of phorbol 12-myristate 13-acetate (PMA), a PKC activator, potentiated CaV2.3 currents by ∼two-fold. After the PMA-induced potentiation, stimulation of M1 receptors decreased the CaV2.3 currents by 52 ± 8%. We examined whether the depletion of phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is responsible for the muscarinic suppression of CaV2.3 currents by using two methods: the Danio rerio voltage-sensing phosphatase (Dr-VSP) system and the rapamycin-induced translocatable pseudojanin (PJ) system. First, dephosphorylation of PI(4,5)P2 to phosphatidylinositol 4-phosphate (PI(4)P) by Dr-VSP significantly suppressed CaV2.3 currents, by 53 ± 3%. Next, dephosphorylation of both PI(4)P and PI(4,5)P2 to PI by PJ translocation further decreased the current by up to 66 ± 3%. The results suggest that CaV2.3 currents are modulated by the M1 receptor in a dual mode-that is, potentiation through the activation of PKC and suppression by the depletion of membrane PI(4,5)P2. Our results also suggest that there is rapid turnover between PI(4)P and PI(4,5)P2 in the plasma membrane.
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Affiliation(s)
- Jin-Young Jeong
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988,
Korea
| | - Hae-Jin Kweon
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988,
Korea
| | - Byung-Chang Suh
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988,
Korea
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24
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Kim DI, Suh BC. Differential interaction of β2e with phosphoinositides: A comparative study between β2e and MARCKS. Channels (Austin) 2015; 10:238-46. [PMID: 26650714 DOI: 10.1080/19336950.2015.1124311] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Voltage-gated calcium (CaV) channels are responsible for Ca(2+) influx in excitable cells. As one of the auxiliary subunits, the CaV β subunit plays a pivotal role in the membrane expression and receptor modulation of CaV channels. In particular, the subcellular localization of the β subunit is critical for determining the biophysical properties of CaV channels. Recently, we showed that the β2e isotype is tethered to the plasma membrane. Such a feature of β2e is due to the reversible electrostatic interaction with anionic membrane phospholipids. Here, we further explored the membrane interaction property of β2e by comparing it with that of myristoylated alanine-rich C kinase substrate (MARCKS). First, the charge neutralization of the inner leaf of the plasma membrane induced the translocation of both β2e and MARCKS to the cytosol, while the transient depletion of poly-phosphoinositides (poly-PIs) by translocatable pseudojanin (PJ) systems induced the cytosolic translocation of β2e but not MARCKS. Second, the activation of protein kinase C (PKC) induced the translocation of MARCKS but not β2e. We also found that after the cytosolic translocation of MARCKS by receptor activation, depletion of poly-PIs slowed the recovery of MARCKS to the plasma membrane. Together, our data demonstrate that both β2e and MARCKS bind to the membrane through electrostatic interaction but with different binding affinity, and thus, they are differentially regulated by enzymatic degradation of membrane PIs.
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Affiliation(s)
- Dong-Il Kim
- a Department of Brain and Cognitive Sciences, DGIST , Daegu , Korea
| | - Byung-Chang Suh
- a Department of Brain and Cognitive Sciences, DGIST , Daegu , Korea
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López Soto EJ, Agosti F, Cabral A, Mustafa ER, Damonte VM, Gandini MA, Rodríguez S, Castrogiovanni D, Felix R, Perelló M, Raingo J. Constitutive and ghrelin-dependent GHSR1a activation impairs CaV2.1 and CaV2.2 currents in hypothalamic neurons. ACTA ACUST UNITED AC 2015; 146:205-19. [PMID: 26283199 PMCID: PMC4555474 DOI: 10.1085/jgp.201511383] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 07/13/2015] [Indexed: 12/22/2022]
Abstract
Constitutive and ligand-dependent GHSR1a activity attenuates CaV2 current and hypothalamic GABA release through distinct mechanisms and signaling pathways. The growth hormone secretagogue receptor type 1a (GHSR1a) has the highest known constitutive activity of any G protein–coupled receptor (GPCR). GHSR1a mediates the action of the hormone ghrelin, and its activation increases transcriptional and electrical activity in hypothalamic neurons. Although GHSR1a is present at GABAergic presynaptic terminals, its effect on neurotransmitter release remains unclear. The activities of the voltage-gated calcium channels, CaV2.1 and CaV2.2, which mediate neurotransmitter release at presynaptic terminals, are modulated by many GPCRs. Here, we show that both constitutive and agonist-dependent GHSR1a activity elicit a strong impairment of CaV2.1 and CaV2.2 currents in rat and mouse hypothalamic neurons and in a heterologous expression system. Constitutive GHSR1a activity reduces CaV2 currents by a Gi/o-dependent mechanism that involves persistent reduction in channel density at the plasma membrane, whereas ghrelin-dependent GHSR1a inhibition is reversible and involves altered CaV2 gating via a Gq-dependent pathway. Thus, GHSR1a differentially inhibits CaV2 channels by Gi/o or Gq protein pathways depending on its mode of activation. Moreover, we present evidence suggesting that GHSR1a-mediated inhibition of CaV2 attenuates GABA release in hypothalamic neurons, a mechanism that could contribute to neuronal activation through the disinhibition of postsynaptic neurons.
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Affiliation(s)
- Eduardo Javier López Soto
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Francina Agosti
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Agustina Cabral
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Emilio Roman Mustafa
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Valentina Martínez Damonte
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Maria Alejandra Gandini
- Department of Cell Biology, Center for Research and Advanced Studies of the National Polytechnic Institute, 07000 México D.F., México
| | - Silvia Rodríguez
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Daniel Castrogiovanni
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Ricardo Felix
- Department of Cell Biology, Center for Research and Advanced Studies of the National Polytechnic Institute, 07000 México D.F., México
| | - Mario Perelló
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
| | - Jesica Raingo
- Laboratory of Electrophysiology and Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE), B1904CMA La Plata, Buenos Aires, Argentina
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Kim DI, Park Y, Jang DJ, Suh BC. Dynamic phospholipid interaction of β2e subunit regulates the gating of voltage-gated Ca2+ channels. ACTA ACUST UNITED AC 2015; 145:529-41. [PMID: 25964431 PMCID: PMC4442786 DOI: 10.1085/jgp.201411349] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 04/10/2015] [Indexed: 12/18/2022]
Abstract
Membrane targeting of the β2e subunit is dynamically regulated by M1 muscarinic receptor signaling to promote fast inactivation of CaV2.2. High voltage-activated Ca2+ (CaV) channels are protein complexes containing pore-forming α1 and auxiliary β and α2δ subunits. The subcellular localization and membrane interactions of the β subunits play a crucial role in regulating CaV channel inactivation and its lipid sensitivity. Here, we investigated the effects of membrane phosphoinositide (PI) turnover on CaV2.2 channel function. The β2 isoform β2e associates with the membrane through electrostatic and hydrophobic interactions. Using chimeric β subunits and liposome-binding assays, we determined that interaction between the N-terminal 23 amino acids of β2e and anionic phospholipids was sufficient for β2e membrane targeting. Binding of the β2e subunit N terminus to liposomes was significantly increased by inclusion of 1% phosphatidylinositol 4,5-bisphosphate (PIP2) in the liposomes, suggesting that, in addition to phosphatidylserine, PIs are responsible for β2e targeting to the plasma membrane. Membrane binding of the β2e subunit slowed CaV2.2 current inactivation. When membrane phosphatidylinositol 4-phosphate and PIP2 were depleted by rapamycin-induced translocation of pseudojanin to the membrane, however, channel opening was decreased and fast inactivation of CaV2.2(β2e) currents was enhanced. Activation of the M1 muscarinic receptor elicited transient and reversible translocation of β2e subunits from membrane to cytosol, but not that of β2a or β3, resulting in fast inactivation of CaV2.2 channels with β2e. These results suggest that membrane targeting of the β2e subunit, which is mediated by nonspecific electrostatic insertion, is dynamically regulated by receptor stimulation, and that the reversible association of β2e with membrane PIs results in functional changes in CaV channel gating. The phospholipid–protein interaction observed here provides structural insight into mechanisms of membrane–protein association and the role of phospholipids in ion channel regulation.
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Affiliation(s)
- Dong-Il Kim
- Department of Brain Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 711-873, Korea
| | - Yongsoo Park
- Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Deok-Jin Jang
- Department of Ecological Science, College of Ecology and Environment, Kyungpook National University, Kyungbuk 742-711, Korea
| | - Byung-Chang Suh
- Department of Brain Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 711-873, Korea
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