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Wu HF, Yu W, Saito-Diaz K, Huang CW, Carey J, Lefcort F, Hart GW, Liu HX, Zeltner N. Norepinephrine transporter defects lead to sympathetic hyperactivity in Familial Dysautonomia models. Nat Commun 2022; 13:7032. [PMID: 36396637 PMCID: PMC9671909 DOI: 10.1038/s41467-022-34811-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 11/08/2022] [Indexed: 11/19/2022] Open
Abstract
Familial dysautonomia (FD), a rare neurodevelopmental and neurodegenerative disorder affects the sympathetic and sensory nervous system. Although almost all patients harbor a mutation in ELP1, it remains unresolved exactly how function of sympathetic neurons (symNs) is affected; knowledge critical for understanding debilitating disease hallmarks, including cardiovascular instability or dysautonomic crises, that result from dysregulated sympathetic activity. Here, we employ the human pluripotent stem cell (hPSC) system to understand symN disease mechanisms and test candidate drugs. FD symNs are intrinsically hyperactive in vitro, in cardiomyocyte co-cultures, and in animal models. We report reduced norepinephrine transporter expression, decreased intracellular norepinephrine (NE), decreased NE re-uptake, and excessive extracellular NE in FD symNs. SymN hyperactivity is not a direct ELP1 mutation result, but may connect to NET via RAB proteins. We found that candidate drugs lowered hyperactivity independent of ELP1 modulation. Our findings may have implications for other symN disorders and may allow future drug testing and discovery.
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Affiliation(s)
- Hsueh-Fu Wu
- Center for Molecular Medicine, University of Georgia, Athens, GA, USA
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA
| | - Wenxin Yu
- Regenerative Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA, USA
| | - Kenyi Saito-Diaz
- Center for Molecular Medicine, University of Georgia, Athens, GA, USA
| | - Chia-Wei Huang
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
| | - Joseph Carey
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Frances Lefcort
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, USA
| | - Gerald W Hart
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
| | - Hong-Xiang Liu
- Regenerative Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA, USA
| | - Nadja Zeltner
- Center for Molecular Medicine, University of Georgia, Athens, GA, USA.
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA.
- Department of Cellular Biology, University of Georgia, Athens, GA, USA.
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2
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Silveirinha VC, Lin H, Tanifuji S, Mochida S, Cottrell GS, Cimarosti H, Stephens GJ. Ca V2.2 (N-type) voltage-gated calcium channels are activated by SUMOylation pathways. Cell Calcium 2021; 93:102326. [PMID: 33360835 DOI: 10.1016/j.ceca.2020.102326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 11/01/2020] [Accepted: 11/23/2020] [Indexed: 11/21/2022]
Abstract
SUMOylation is an important post-translational modification process involving covalent attachment of SUMO (Small Ubiquitin-like MOdifier) protein to target proteins. Here, we investigated the potential for SUMO-1 protein to modulate the function of the CaV2.2 (N-type) voltage-gated calcium channel (VGCC), a protein vital for presynaptic neurotransmitter release. Co-expression of SUMO-1, but not the conjugation-deficient mutant SUMO-1ΔGG, increased heterologously-expressed CaV2.2 Ca2+ current density, an effect potentiated by the conjugating enzyme Ubc9. Expression of sentrin-specific protease (SENP)-1 or Ubc9 alone, had no effect on recombinant CaV2.2 channels. Co-expression of SUMO-1 and Ubc9 caused an increase in whole-cell maximal conductance (Gmax) and a hyperpolarizing shift in the midpoint of activation (V1/2). Mutation of all five CaV2.2 lysine residues to arginine within the five highest probability (>65 %) SUMOylation consensus motifs (SCMs) (construct CaV2.2-Δ5KR), produced a loss-of-function mutant. Mutagenesis of selected individual lysine residues identified K394, but not K951, as a key residue for SUMO-1-mediated increase in CaV2.2 Ca2+ current density. In synaptically-coupled superior cervical ganglion (SCG) neurons, SUMO-1 protein was distributed throughout the cell body, axons and dendrites and presumptive presynaptic terminals, whilst SUMO-1ΔGG protein was largely confined to the cell body, in particular, the nucleus. SUMO-1 expression caused increases in paired excitatory postsynaptic potential (EPSP) ratio at short (20-120 ms) inter-stimuli intervals in comparison to SUMO-1ΔGG, consistent with an increase in residual presynaptic Ca2+ current and an increase in release probability of synaptic vesicles. Together, these data provide evidence for CaV2.2 VGCCs as novel targets for SUMOylation pathways.
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Affiliation(s)
- Vasco C Silveirinha
- School of Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AJ, UK
| | - Hong Lin
- School of Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AJ, UK
| | - Shota Tanifuji
- Dept of Physiology, Tokyo Medical University, Tokyo, Japan
| | - Sumiko Mochida
- Dept of Physiology, Tokyo Medical University, Tokyo, Japan
| | - Graeme S Cottrell
- School of Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AJ, UK
| | - Helena Cimarosti
- School of Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AJ, UK.
| | - Gary J Stephens
- School of Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AJ, UK.
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3
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Mochida S. Neurotransmitter Release Site Replenishment and Presynaptic Plasticity. Int J Mol Sci 2020; 22:ijms22010327. [PMID: 33396919 PMCID: PMC7794938 DOI: 10.3390/ijms22010327] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 12/23/2020] [Accepted: 12/27/2020] [Indexed: 12/19/2022] Open
Abstract
An action potential (AP) triggers neurotransmitter release from synaptic vesicles (SVs) docking to a specialized release site of presynaptic plasma membrane, the active zone (AZ). The AP simultaneously controls the release site replenishment with SV for sustainable synaptic transmission in response to incoming neuronal signals. Although many studies have suggested that the replenishment time is relatively slow, recent studies exploring high speed resolution have revealed SV dynamics with milliseconds timescale after an AP. Accurate regulation is conferred by proteins sensing Ca2+ entering through voltage-gated Ca2+ channels opened by an AP. This review summarizes how millisecond Ca2+ dynamics activate multiple protein cascades for control of the release site replenishment with release-ready SVs that underlie presynaptic short-term plasticity.
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Affiliation(s)
- Sumiko Mochida
- Department of Physiology, Tokyo Medical University, Tokyo 160-8402, Japan
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4
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Presynaptic Calcium Channels. Int J Mol Sci 2019; 20:ijms20092217. [PMID: 31064106 PMCID: PMC6539076 DOI: 10.3390/ijms20092217] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 04/22/2019] [Accepted: 04/26/2019] [Indexed: 12/27/2022] Open
Abstract
Presynaptic Ca2+ entry occurs through voltage-gated Ca2+ (CaV) channels which are activated by membrane depolarization. Depolarization accompanies neuronal firing and elevation of Ca2+ triggers neurotransmitter release from synaptic vesicles. For synchronization of efficient neurotransmitter release, synaptic vesicles are targeted by presynaptic Ca2+ channels forming a large signaling complex in the active zone. The presynaptic CaV2 channel gene family (comprising CaV2.1, CaV2.2, and CaV2.3 isoforms) encode the pore-forming α1 subunit. The cytoplasmic regions are responsible for channel modulation by interacting with regulatory proteins. This article overviews modulation of the activity of CaV2.1 and CaV2.2 channels in the control of synaptic strength and presynaptic plasticity.
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5
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Presynaptic calcium channels. Neurosci Res 2018; 127:33-44. [DOI: 10.1016/j.neures.2017.09.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 07/13/2017] [Accepted: 08/23/2017] [Indexed: 12/30/2022]
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6
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SAD-B Phosphorylation of CAST Controls Active Zone Vesicle Recycling for Synaptic Depression. Cell Rep 2017; 16:2901-2913. [PMID: 27626661 DOI: 10.1016/j.celrep.2016.08.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 06/28/2016] [Accepted: 08/05/2016] [Indexed: 12/25/2022] Open
Abstract
Short-term synaptic depression (STD) is a common form of activity-dependent plasticity observed widely in the nervous system. Few molecular pathways that control STD have been described, but the active zone (AZ) release apparatus provides a possible link between neuronal activity and plasticity. Here, we show that an AZ cytomatrix protein CAST and an AZ-associated protein kinase SAD-B coordinately regulate STD by controlling reloading of the AZ with release-ready synaptic vesicles. SAD-B phosphorylates the N-terminal serine (S45) of CAST, and S45 phosphorylation increases with higher firing rate. A phosphomimetic CAST (S45D) mimics CAST deletion, which enhances STD by delaying reloading of the readily releasable pool (RRP), resulting in a pool size decrease. A phosphonegative CAST (S45A) inhibits STD and accelerates RRP reloading. Our results suggest that the CAST/SAD-B reaction serves as a brake on synaptic transmission by temporal calibration of activity and synaptic depression via RRP size regulation.
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7
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Saur T, Cohen BM, Ma Q, Babb SM, Buttner EA, Yao WD. Acute and chronic effects of clozapine on cholinergic transmission in cultured mouse superior cervical ganglion neurons. J Neurogenet 2016; 30:297-305. [PMID: 27627024 PMCID: PMC6061957 DOI: 10.1080/01677063.2016.1229779] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 08/18/2016] [Accepted: 08/24/2016] [Indexed: 10/21/2022]
Abstract
Cholinergic dysfunction contributes to cognitive deficits in schizophrenia. The atypical antipsychotic clozapine improves cognition in patients with schizophrenia, possibly through modulation of the cholinergic system. However, little is known about specific underlying mechanisms. We investigated the acute and chronic effects of clozapine on cholinergic synaptic transmission in cultured superior cervical ganglion (SCG) neurons. Spontaneous excitatory postsynaptic currents (sEPSCs) were detected and were reversibly inhibited by the nicotinic receptor antagonist d-tubocurarine, confirming that the synaptic responses were primarily mediated by nicotinic receptors. Bath application of clozapine at therapeutic concentrations rapidly and reversely inhibited both the amplitude and frequency of sEPSCs in a concentration-dependent manner, without changing either rise or decay time, suggesting that clozapine effects have both presynaptic and postsynaptic origins. The acute effects of clozapine on sEPSCs were recapitulated by chronic treatment of SCG cultures with similar concentrations of clozapine, as clozapine treatment for 4 d reduced the frequency and amplitude of sEPSCs without affecting their kinetics. Cell survival analysis indicated that SCG neuron cell counts after chronic clozapine treatment were comparable to the control group. These results demonstrate that therapeutic concentrations of clozapine suppress nicotinic synaptic transmission in SCG cholinergic synapses, a simple in vitro preparation of cholinergic transmission.
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Affiliation(s)
- Taixiang Saur
- a McLean Hospital/Harvard Medical School , Belmont , MA , USA
| | - Bruce M Cohen
- a McLean Hospital/Harvard Medical School , Belmont , MA , USA
| | - Qi Ma
- b New England Primate Research Center, Harvard Medical School , Southborough , MA , USA
| | - Suzann M Babb
- a McLean Hospital/Harvard Medical School , Belmont , MA , USA
| | - Edgar A Buttner
- a McLean Hospital/Harvard Medical School , Belmont , MA , USA
| | - Wei-Dong Yao
- b New England Primate Research Center, Harvard Medical School , Southborough , MA , USA
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8
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Optimization of neuronal cultures from rat superior cervical ganglia for dual patch recording. Sci Rep 2015; 5:14455. [PMID: 26399440 PMCID: PMC4585864 DOI: 10.1038/srep14455] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 08/12/2015] [Indexed: 12/29/2022] Open
Abstract
Superior cervical ganglion neurons (SCGN) are often used to investigate neurotransmitter release mechanisms. In this study, we optimized the dissociation and culture conditions of rat SCGN cultures for dual patch clamp recordings. Two weeks in vitro are sufficient to achieve a significant CNTF-induced cholinergic switch and to develop mature and healthy neuronal profiles suited for detailed patch clamp analysis. One single pup provides sufficient material to prepare what was formerly obtained from 12 to 15 animals. The suitability of these cultures to study neurotransmitter release mechanisms was validated by presynaptically perturbing the interaction of the v-SNARE VAMP2 with the vesicular V-ATPase V0c subunit.
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9
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Neural activity selects myosin IIB and VI with a specific time window in distinct dynamin isoform-mediated synaptic vesicle reuse pathways. J Neurosci 2015; 35:8901-13. [PMID: 26063922 DOI: 10.1523/jneurosci.5028-14.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Presynaptic nerve terminals must maintain stable neurotransmissions via synaptic vesicle (SV) resupply despite encountering wide fluctuations in the number and frequency of incoming action potentials (APs). However, the molecular mechanism linking variation in neural activity to SV resupply is unknown. Myosins II and VI are actin-based cytoskeletal motors that drive dendritic actin dynamics and membrane transport, respectively, at brain synapses. Here we combined genetic knockdown or molecular dysfunction and direct physiological measurement of fast synaptic transmission from paired rat superior cervical ganglion neurons in culture to show that myosins IIB and VI work individually in SV reuse pathways, having distinct dependency and time constants with physiological AP frequency. Myosin VI resupplied the readily releasable pool (RRP) with slow kinetics independently of firing rates but acted quickly within 50 ms after AP. Under high-frequency AP firing, myosin IIB resupplied the RRP with fast kinetics in a slower time window of 200 ms. Knockdown of both myosin and dynamin isoforms by mixed siRNA microinjection revealed that myosin IIB-mediated SV resupply follows amphiphysin/dynamin-1-mediated endocytosis, while myosin VI-mediated SV resupply follows dynamin-3-mediated endocytosis. Collectively, our findings show how distinct myosin isoforms work as vesicle motors in appropriate SV reuse pathways associated with specific firing patterns.
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10
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Vogl C, Tanifuji S, Danis B, Daniels V, Foerch P, Wolff C, Whalley BJ, Mochida S, Stephens GJ. Synaptic vesicle glycoprotein 2A modulates vesicular release and calcium channel function at peripheral sympathetic synapses. Eur J Neurosci 2014; 41:398-409. [PMID: 25484265 DOI: 10.1111/ejn.12799] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 11/03/2014] [Accepted: 11/05/2014] [Indexed: 12/01/2022]
Abstract
Synaptic vesicle glycoprotein (SV)2A is a transmembrane protein found in secretory vesicles and is critical for Ca(2+) -dependent exocytosis in central neurons, although its mechanism of action remains uncertain. Previous studies have proposed, variously, a role of SV2 in the maintenance and formation of the readily releasable pool (RRP) or in the regulation of Ca(2+) responsiveness of primed vesicles. Such previous studies have typically used genetic approaches to ablate SV2 levels; here, we used a strategy involving small interference RNA (siRNA) injection to knockdown solely presynaptic SV2A levels in rat superior cervical ganglion (SCG) neuron synapses. Moreover, we investigated the effects of SV2A knockdown on voltage-dependent Ca(2+) channel (VDCC) function in SCG neurons. Thus, we extended the studies of SV2A mechanisms by investigating the effects on vesicular transmitter release and VDCC function in peripheral sympathetic neurons. We first demonstrated an siRNA-mediated SV2A knockdown. We showed that this SV2A knockdown markedly affected presynaptic function, causing an attenuated RRP size, increased paired-pulse depression and delayed RRP recovery after stimulus-dependent depletion. We further demonstrated that the SV2A-siRNA-mediated effects on vesicular release were accompanied by a reduction in VDCC current density in isolated SCG neurons. Together, our data showed that SV2A is required for correct transmitter release at sympathetic neurons. Mechanistically, we demonstrated that presynaptic SV2A: (i) acted to direct normal synaptic transmission by maintaining RRP size, (ii) had a facilitatory role in recovery from synaptic depression, and that (iii) SV2A deficits were associated with aberrant Ca(2+) current density, which may contribute to the secretory phenotype in sympathetic peripheral neurons.
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11
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Mori M, Tanifuji S, Mochida S. Kinetic organization of Ca2+ signals that regulate synaptic release efficacy in sympathetic neurons. Mol Pharmacol 2014; 86:297-305. [PMID: 24981043 DOI: 10.1124/mol.114.094029] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Calcium regulation of neurotransmitter release is essential for maintenance of synaptic transmission. However, the temporal and spatial organization of Ca(2+) dynamics that regulate synaptic vesicle (SV) release efficacy in sympathetic neurons is poorly understood. Here, we investigate the N-type Ca(2+) channel-mediated kinetic structure of Ca(2+) regulation of cholinergic transmission of sympathetic neurons. We measured the effect of Ca(2+) chelation with fast 1,2-bis(2-aminophenoxy) ethane-tetraacetic acid (BAPTA) and slow ethyleneglycol-tetraacetic acid (EGTA) buffers on exocytosis, synaptic depression, and recovery of the readily releasable vesicle pool (RRP), after both single action potential (AP) and repetitive APs. Surprisingly, postsynaptic potentials peaking at ~12 milliseconds after the AP was inhibited by both rapid and slow Ca(2+) buffers suggests that, in addition to the well known fast Ca(2+) signals at the active zone (AZ), slow Ca(2+) signals at the peak of Ca(2+) entry also contribute to paired-pulse or repetitive AP responses. Following a single AP, discrete Ca(2+) transient increase regulated synaptic depression in rapid (<30-millisecond) and slow (<120-millisecond) phases. In contrast, following prolonged AP trains, synaptic depression was reduced by a slow Ca(2+) signal regulation lasting >200 milliseconds. Finally, after an AP burst, recovery of the RRP was mediated by an AP-dependent rapid Ca(2+) signal, and the expansion of releasable SV number by an AP firing activity-dependent slow Ca(2+) signal. These data indicate that local Ca(2+) signals operating near Ca(2+) sources in the AZ are organized into discrete fast and slow temporal phases that remodel exocytosis and short-term plasticity to ensure long-term stability in acetylcholine release efficacy.
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Affiliation(s)
- Michinori Mori
- Department of Physiology, Tokyo Medical University, Tokyo, Japan
| | - Shota Tanifuji
- Department of Physiology, Tokyo Medical University, Tokyo, Japan
| | - Sumiko Mochida
- Department of Physiology, Tokyo Medical University, Tokyo, Japan
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12
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Abstract
Calcium is important in controlling nuclear gene expression through the activation of multiple signal-transduction pathways in neurons. Compared with other voltage-gated calcium channels, CaV1 channels demonstrate a considerable advantage in signalling to the nucleus. In this review, we summarize the recent progress in elucidating the mechanisms involved. CaV1 channels, already advantaged in their responsiveness to depolarization, trigger communication with the nucleus by attracting colocalized clusters of activated CaMKII (Ca2+/calmodulin-dependent protein kinase II). CaV2 channels lack this ability, but must work at a distance of >1 μm from the CaV1-CaMKII co-clusters, which hampers their relative efficiency for a given rise in bulk [Ca2+]i (intracellular [Ca2+]). Moreover, Ca2+ influx from CaV2 channels is preferentially buffered by the ER (endoplasmic reticulum) and mitochondria, further attenuating their effectiveness in signalling to the nucleus.
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13
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Bucci G, Mochida S, Stephens GJ. Inhibition of synaptic transmission and G protein modulation by synthetic CaV2.2 Ca²+ channel peptides. J Physiol 2011; 589:3085-101. [PMID: 21521766 PMCID: PMC3145926 DOI: 10.1113/jphysiol.2010.204735] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Accepted: 04/19/2011] [Indexed: 12/27/2022] Open
Abstract
Modulation of presynaptic voltage-dependent Ca2+ channels is a major means of controlling neurotransmitter release. The CaV2.2Ca2+ channel subunit contains several inhibitory interaction sites for Gβγ subunits, including the amino terminal (NT) and I-II loop. The NT and I-II loop have also been proposed to undergo a G protein-gated inhibitory interaction, whilst the NT itself has also been proposed to suppress CaV2 channel activity. Here, we investigate the effects of an amino terminal (CaV2.2[45-55]) 'NT peptide' and a I-II loop alpha interaction domain (CaV2.2[377-393]) 'AID peptide' on synaptic transmission, Ca2+ channel activity and G protein modulation in superior cervical ganglion neurones (SCGNs). Presynaptic injection of NT or AID peptide into SCGN synapses inhibited synaptic transmission and also attenuated noradrenaline-induced G protein modulation. In isolated SCGNs, NT and AID peptides reduced whole-cell Ca2+ current amplitude, modified voltage dependence of Ca2+ channel activation and attenuated noradrenaline-induced G protein modulation. Co-application of NT and AID peptide negated inhibitory actions. Together, these data favour direct peptide interaction with presynaptic Ca2+ channels, with effects on current amplitude and gating representing likely mechanisms responsible for inhibition of synaptic transmission. Mutations to residues reported as determinants of Ca2+ channel function within the NT peptide negated inhibitory effects on synaptic transmission, Ca2+ current amplitude and gating and G protein modulation. A mutation within the proposed QXXER motif for G protein modulation did not abolish inhibitory effects of the AID peptide. This study suggests that the CaV2.2 amino terminal and I-II loop contribute molecular determinants for Ca2+ channel function; the data favour a direct interaction of peptides with Ca2+ channels to inhibit synaptic transmission and attenuate G protein modulation.
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Affiliation(s)
- Giovanna Bucci
- School of Pharmacy, University of Reading, Whiteknights, Reading RG6 6AJ, UK
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14
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Mochida S. Ca/Calmodulin and presynaptic short-term plasticity. ISRN NEUROLOGY 2011; 2011:919043. [PMID: 22389834 PMCID: PMC3263560 DOI: 10.5402/2011/919043] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Accepted: 04/18/2011] [Indexed: 11/23/2022]
Abstract
Synaptic efficacy is remodeled by neuronal firing activity at the presynaptic terminal. Presynaptic activity-dependent changes in transmitter release induce postsynaptic plasticity, including morphological change in spine, gene transcription, and protein synthesis and trafficking. The presynaptic transmitter release is triggered and regulated by Ca2+, which enters through voltage-gated Ca2+ (CaV) channels and diffuses into the presynaptic terminal accompanying action potential firings. Residual Ca2+ is sensed by Ca2+-binding proteins, among other potential actions, it mediates time- and space-dependent synaptic facilitation and depression via effects on CaV2 channel gating and vesicle replenishment in the readily releasable pool (RRP). Calmodulin, a Ca2+-sensor protein with an EF-hand motif that binds Ca2+, interacts with CaV2 channels and autoreceptors in modulation of SNARE-mediated exocytosis.
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Affiliation(s)
- Sumiko Mochida
- Department of Physiology, Tokyo Medical University, 1-1 Shinjuku-6-chome, Shinjuku-ku, Tokyo 160-8402, Japan
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15
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Activity-dependent regulation of synaptic vesicle exocytosis and presynaptic short-term plasticity. Neurosci Res 2011; 70:16-23. [DOI: 10.1016/j.neures.2011.03.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Revised: 01/25/2011] [Accepted: 03/15/2011] [Indexed: 11/23/2022]
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16
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Yamamoto Y, Mochida S, Miyazaki N, Kawai K, Fujikura K, Kurooka T, Iwasaki K, Sakisaka T. Tomosyn inhibits synaptotagmin-1-mediated step of Ca2+-dependent neurotransmitter release through its N-terminal WD40 repeats. J Biol Chem 2010; 285:40943-55. [PMID: 20978127 DOI: 10.1074/jbc.m110.156893] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neurotransmitter release is triggered by Ca(2+) binding to a low affinity Ca(2+) sensor, mostly synaptotagmin-1, which catalyzes SNARE-mediated synaptic vesicle fusion. Tomosyn negatively regulates Ca(2+)-dependent neurotransmitter release by sequestering target SNAREs through the C-terminal VAMP-like domain. In addition to the C terminus, the N-terminal WD40 repeats of tomosyn also have potent inhibitory activity toward Ca(2+)-dependent neurotransmitter release, although the molecular mechanism underlying this effect remains elusive. Here, we show that through its N-terminal WD40 repeats tomosyn directly binds to synaptotagmin-1 in a Ca(2+)-dependent manner. The N-terminal WD40 repeats impaired the activities of synaptotagmin-1 to promote SNARE complex-mediated membrane fusion and to bend the lipid bilayers. Decreased acetylcholine release from N-terminal WD40 repeat-microinjected superior cervical ganglion neurons was relieved by microinjection of the cytoplasmic domain of synaptotagmin-1. These results indicate that, upon direct binding, the N-terminal WD40 repeats negatively regulate the synaptotagmin-1-mediated step of Ca(2+)-dependent neurotransmitter release. Furthermore, we show that synaptotagmin-1 binding enhances the target SNARE-sequestering activity of tomosyn. These results suggest that the interplay between tomosyn and synaptotagmin-1 underlies inhibitory control of Ca(2+)-dependent neurotransmitter release.
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Affiliation(s)
- Yasunori Yamamoto
- Division of Membrane Dynamics, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
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17
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Di Giovanni J, Boudkkazi S, Mochida S, Bialowas A, Samari N, Lévêque C, Youssouf F, Brechet A, Iborra C, Maulet Y, Moutot N, Debanne D, Seagar M, El Far O. V-ATPase Membrane Sector Associates with Synaptobrevin to Modulate Neurotransmitter Release. Neuron 2010; 67:268-79. [DOI: 10.1016/j.neuron.2010.06.024] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/22/2010] [Indexed: 10/19/2022]
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18
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Abstract
Newly synthesized synaptic proteins and mitochondria are transported along lengthy neuronal processes to assist in the proper assembly of developing synapses and activity-dependent remodeling of mature synapses. Neuronal transport is mediated by motor proteins that associate with their cargoes via adaptors and travel along the cytoskeleton within neuronal processes. Our previous studies in developing hippocampal neurons revealed that syntabulin acts as a KIF5B motor adaptor and mediates anterograde transport of presynaptic cargoes and mitochondria, presynaptic assembly, and activity-induced plasticity. Here, using cultured superior cervical ganglion neurons combined with manipulation of syntabulin expression or interference with its interaction with KIF5B, we uncover a crucial role for syntabulin in the maintenance of presynaptic function. Syntabulin loss-of-function delayed the appearance of synaptic activity in developing neurons and impaired synaptic transmission in mature neurons, including reduced basal activity, accelerated synaptic depression under high-frequency firing, slowed recovery rates after synaptic vesicle depletion, and impaired presynaptic short-term plasticity. These defects correlated with reduced mitochondrial distribution along neuronal processes and were rescued by the application of ATP within presynaptic neurons. These results suggest that syntabulin supports the axonal transport of mitochondria and concomitant ATP production at presynaptic terminals. ATP supply from locally stationed mitochondria is in turn necessary for the efficient mobilization of synaptic vesicles into the readily releasable pool. These findings emphasize the critical role of KIF5B-syntabulin-mediated axonal transport in the maintenance of presynaptic function and regulation of synaptic plasticity.
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Yamamoto Y, Mochida S, Kurooka T, Sakisaka T. Reciprocal intramolecular interactions of tomosyn control its inhibitory activity on SNARE complex formation. J Biol Chem 2009; 284:12480-90. [PMID: 19258327 DOI: 10.1074/jbc.m807182200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Neurotransmitter release from presynaptic nerve terminals is regulated by SNARE complex-mediated synaptic vesicle fusion. Tomosyn, a negative regulator of neurotransmitter release, which is composed of N-terminal WD40 repeats, a tail domain, and a C-terminal VAMP-like domain, is known to inhibit SNARE complex formation by sequestering target SNAREs (t-SNAREs) upon interaction of its C-terminal VAMP-like domain with t-SNAREs. However, it remains unclear how the inhibitory activity of tomosyn is regulated. Here we show that the tail domain functions as a regulator of the inhibitory activity of tomosyn through intramolecular interactions. The binding of the tail domain to the C-terminal VAMP-like domain interfered with the interaction of the C-terminal VAMP-like domain with t-SNAREs, and thereby repressed the inhibitory activity of tomosyn on the SNARE complex formation. The repressed inhibitory activity of tomosyn was restored by the binding of the tail domain to the N-terminal WD40 repeats. These results indicate that the probable conformational change of tomosyn mediated by the intramolecular interactions of the tail domain controls its inhibitory activity on the SNARE complex formation, leading to a regulated inhibition of neurotransmitter release.
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Affiliation(s)
- Yasunori Yamamoto
- Division of Membrane Dynamics, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
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Lu W, Ma H, Sheng ZH, Mochida S. Dynamin and Activity Regulate Synaptic Vesicle Recycling in Sympathetic Neurons. J Biol Chem 2009; 284:1930-7. [DOI: 10.1074/jbc.m803691200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Sakisaka T, Yamamoto Y, Mochida S, Nakamura M, Nishikawa K, Ishizaki H, Okamoto-Tanaka M, Miyoshi J, Fujiyoshi Y, Manabe T, Takai Y. Dual inhibition of SNARE complex formation by tomosyn ensures controlled neurotransmitter release. ACTA ACUST UNITED AC 2008; 183:323-37. [PMID: 18936251 PMCID: PMC2568027 DOI: 10.1083/jcb.200805150] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Neurotransmitter release from presynaptic nerve terminals is regulated by soluble NSF attachment protein receptor (SNARE) complex–mediated synaptic vesicle fusion. Tomosyn inhibits SNARE complex formation and neurotransmitter release by sequestering syntaxin-1 through its C-terminal vesicle-associated membrane protein (VAMP)–like domain (VLD). However, in tomosyn-deficient mice, the SNARE complex formation is unexpectedly decreased. In this study, we demonstrate that the N-terminal WD-40 repeat domain of tomosyn catalyzes the oligomerization of the SNARE complex. Microinjection of the tomosyn N-terminal WD-40 repeat domain into neurons prevented stimulated acetylcholine release. Thus, tomosyn inhibits neurotransmitter release by catalyzing oligomerization of the SNARE complex through the N-terminal WD-40 repeat domain in addition to the inhibitory activity of the C-terminal VLD.
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Affiliation(s)
- Toshiaki Sakisaka
- Division of Membrane Dynamics, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
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