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Jackson MB, Chiang CW, Cheng J. Fusion pore flux controls the rise-times of quantal synaptic responses. J Gen Physiol 2024; 156:e202313484. [PMID: 38860965 PMCID: PMC11167452 DOI: 10.1085/jgp.202313484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 03/18/2024] [Accepted: 05/27/2024] [Indexed: 06/12/2024] Open
Abstract
The release of neurotransmitter from a single synaptic vesicle generates a quantal response, which at excitatory synapses in voltage-clamped neurons is referred to as a miniature excitatory postsynaptic current (mEPSC). We analyzed mEPSCs in cultured mouse hippocampal neurons and in HEK cells expressing postsynaptic proteins enabling them to receive synaptic inputs from cocultured neurons. mEPSC amplitudes and rise-times varied widely within and between cells. In neurons, mEPSCs with larger amplitudes had longer rise-times, and this correlation was stronger in neurons with longer mean rise-times. In HEK cells, this correlation was weak and unclear. Standard mechanisms thought to govern mEPSCs cannot account for these results. We therefore developed models to simulate mEPSCs and assess their dependence on different factors. Modeling indicated that longer diffusion times for transmitters released by larger vesicles to reach more distal receptors cannot account for the correlation between rise-time and amplitude. By contrast, incorporating the vesicle size dependence of fusion pore expulsion time recapitulated experimental results well. Larger vesicles produce mEPSCs with larger amplitudes and also take more time to lose their content. Thus, fusion pore flux directly contributes to mEPSC rise-time. Variations in fusion pores account for differences among neurons, between neurons and HEK cells, and the correlation between rise-time and the slope of rise-time versus amplitude plots. Plots of mEPSC amplitude versus rise-time are sensitive to otherwise inaccessible properties of a synapse and offer investigators a means of assessing the role of fusion pores in synaptic release.
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Affiliation(s)
- Meyer B. Jackson
- Department of Neuroscience, University of Wisconsin—Madison, Madison, WI, USA
| | - Chung-Wei Chiang
- Department of Neuroscience, University of Wisconsin—Madison, Madison, WI, USA
| | - Jinbo Cheng
- Department of Neuroscience, University of Wisconsin—Madison, Madison, WI, USA
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Cho W, Jung M, Yoon SH, Jeon J, Oh MA, Kim JY, Park M, Kang CM, Chung TD. On-Site Formation of Functional Dopaminergic Presynaptic Terminals on Neuroligin-2-Modified Gold-Coated Microspheres. ACS APPLIED MATERIALS & INTERFACES 2024; 16:3082-3092. [PMID: 38206769 DOI: 10.1021/acsami.3c13829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
Advancements in neural interface technologies have enabled the direct connection of neurons and electronics, facilitating chemical communication between neural systems and external devices. One promising approach is a synaptogenesis-involving method, which offers an opportunity for synaptic signaling between these systems. Janus synapses, one type of synaptic interface utilizing synaptic cell adhesion molecules for interface construction, possess unique features that enable the determination of location, direction of signal flow, and types of neurotransmitters involved, promoting directional and multifaceted communication. This study presents the first successful establishment of a Janus synapse between dopaminergic (DA) neurons and abiotic substrates by using a neuroligin-2 (NLG2)-mediated synapse-inducing method. NLG2 immobilized on gold-coated microspheres can induce synaptogenesis upon contact with spatially isolated DA axons. The induced DA Janus synapses exhibit stable synaptic activities comparable to that of native synapses over time, suggesting their suitability for application in neural interfaces. By calling for DA presynaptic organizations, the NLG2-immobilized abiotic substrate is a promising tool for the on-site detection of synaptic dopamine release.
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Affiliation(s)
- Wonkyung Cho
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Minji Jung
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Sun-Heui Yoon
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Joohee Jeon
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Min-Ah Oh
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Ji Yong Kim
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Minjung Park
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Chung Mu Kang
- Advanced Institutes of Convergence Technology, Suwon-si 16229, Gyeonggi-do, Republic of Korea
| | - Taek Dong Chung
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
- Advanced Institutes of Convergence Technology, Suwon-si 16229, Gyeonggi-do, Republic of Korea
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Kuanyshbek A, Wang M, Andersson Å, Tuifua M, Palmer EE, Sachdev RK, Mu TW, Vetter I, Keramidas A. Anti-seizure mechanisms of midazolam and valproate at the β2(L51M) variant of the GABA A receptor. Neuropharmacology 2022; 221:109295. [PMID: 36257447 PMCID: PMC9981329 DOI: 10.1016/j.neuropharm.2022.109295] [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: 02/13/2022] [Revised: 10/07/2022] [Accepted: 10/11/2022] [Indexed: 11/05/2022]
Abstract
Genetic sequencing is identifying an expanding number of variants of GABAA receptors associated with human epilepsies. We identified a new de novo variant of the β2 subunit (β2L51M) of the inhibitory GABAA receptor associated with seizures. Our analysis determined the pathogenicity of the variant and the effects of anti-seizure medications. Our data demonstrates that the variant reduced cell surface trafficking and peak GABA-gated currents. Synaptic currents mediated by variant-containing receptors decayed faster than wild-type and single receptor currents showed that the variant shortened the duration of receptor activity by decreasing receptor open times. We tested the effects of the anti-seizure medications, midazolam, carbamazepine and valproate and found that all three enhance variant receptor surface expression. Additionally, midazolam restored receptor function by increasing single receptor active periods and synaptic current decay times towards wild-type levels. By contrast, valproate increased synaptic peak currents, event frequency and promoted synaptic bursting. Our study identifies a new disease-causing variant to the GABAA receptor, profiles its pathogenic effects and demonstrates how anti-seizure drugs correct its functional deficits.
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Affiliation(s)
- Alibek Kuanyshbek
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Meng Wang
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Åsa Andersson
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Marie Tuifua
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Elizabeth E Palmer
- Sydney Children's Hospital Network, Randwick Sydney Australia and School of Women's and Children's Health, UNSW Medicine, The University of New South Wales, Sydney, NSW, Australia
| | - Rani K Sachdev
- Sydney Children's Hospital Network, Randwick Sydney Australia and School of Women's and Children's Health, UNSW Medicine, The University of New South Wales, Sydney, NSW, Australia
| | - Ting-Wei Mu
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Irina Vetter
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia; School of Pharmacy, The University of Queensland, Woolloongabba, Queensland, 4102, Australia
| | - Angelo Keramidas
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia.
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Fu L, Yu B, Li Z, Liu Z. The therapeutic potential of ultra-short-acting β-receptor antagonists in perioperative analgesic: Evidence from preclinical and clinical studies. Front Pharmacol 2022; 13:914710. [PMID: 36304145 PMCID: PMC9592752 DOI: 10.3389/fphar.2022.914710] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 09/20/2022] [Indexed: 12/04/2022] Open
Abstract
Perioperative multimodal analgesia can reduce the side effects of a high concentration of opioids, improving the comfort of the patient. However, insufficient analgesia of this model has prompted researchers to explore new adjuvant analgesics. Recently, an increasing number of studies have found a low-grade analgesic effect in the clinical application of ultra-short-acting β-adrenergic receptor antagonists, which are conventionally used as pharmacologic agents in the cardiovascular system. The mechanism by which ultra-short-acting β-antagonists exert antinociceptive effects has not been clarified yet. In this review, we intend to address its potential reasons from the side of neurotransmitters, inflammatory cytokines, and signaling pathways, providing theoretical proof for the application of β-adrenergic receptor antagonists in analgesia.
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Affiliation(s)
- Linbin Fu
- Department of Anesthesiology, Shenzhen Second People’s Hospital (Shenzhen Institute of Translational Medicine), The First Affiliated Hospital of Shenzhen University, Shenzhen, China
| | - Buwei Yu
- Department of Anesthesiology, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zheng Li
- Department of Anesthesiology, Shenzhen Second People’s Hospital (Shenzhen Institute of Translational Medicine), The First Affiliated Hospital of Shenzhen University, Shenzhen, China
- *Correspondence: Zheng Li, ; Zhiheng Liu,
| | - Zhiheng Liu
- Department of Anesthesiology, Shenzhen Second People’s Hospital (Shenzhen Institute of Translational Medicine), The First Affiliated Hospital of Shenzhen University, Shenzhen, China
- *Correspondence: Zheng Li, ; Zhiheng Liu,
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Short B. Dissecting neurotransmission with artificial synapses. J Gen Physiol 2021; 153:211979. [PMID: 33847732 PMCID: PMC8047795 DOI: 10.1085/jgp.202112930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
JGP study demonstrates how recordings from neuron–HEK cell cocultures provide a clearer picture of the factors involved in synaptic transmission.
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