1
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Hendricks EL, Liebl FLW. The CHD family chromatin remodeling enzyme, Kismet, promotes both clathrin-mediated and activity-dependent bulk endocytosis. PLoS One 2024; 19:e0300255. [PMID: 38512854 PMCID: PMC10956772 DOI: 10.1371/journal.pone.0300255] [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: 07/18/2023] [Accepted: 02/23/2024] [Indexed: 03/23/2024] Open
Abstract
Chromodomain helicase DNA binding domain (CHD) proteins, including CHD7 and CHD8, remodel chromatin to enable transcriptional programs. Both proteins are important for proper neural development as heterozygous mutations in Chd7 and Chd8 are causative for CHARGE syndrome and correlated with autism spectrum disorders, respectively. Their roles in mature neurons are poorly understood despite influencing the expression of genes required for cell adhesion, neurotransmission, and synaptic plasticity. The Drosophila homolog of CHD7 and CHD8, Kismet (Kis), promotes neurotransmission, endocytosis, and larval locomotion. Endocytosis is essential in neurons for replenishing synaptic vesicles, maintaining protein localization, and preserving the size and composition of the presynaptic membrane. Several forms of endocytosis have been identified including clathrin-mediated endocytosis, which is coupled with neural activity and is the most prevalent form of synaptic endocytosis, and activity-dependent bulk endocytosis, which occurs during periods of intense stimulation. Kis modulates the expression of gene products involved in endocytosis including promoting shaggy/GSK3β expression while restricting PI3K92E. kis mutants electrophysiologically phenocopy a liquid facets mutant in response to paradigms that induce clathrin-mediated endocytosis and activity-dependent bulk endocytosis. Further, kis mutants do not show further reductions in endocytosis when activity-dependent bulk endocytosis or clathrin-mediated endocytosis are pharmacologically inhibited. We find that Kis is important in postsynaptic muscle for proper endocytosis but the ATPase domain of Kis is dispensable for endocytosis. Collectively, our data indicate that Kis promotes both clathrin-mediated endocytosis and activity-dependent bulk endocytosis possibly by promoting transcription of several endocytic genes and maintaining the size of the synaptic vesicle pool.
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Affiliation(s)
- Emily L. Hendricks
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, Illinois, United States of America
| | - Faith L. W. Liebl
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, Illinois, United States of America
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2
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Seidenthal M, Jánosi B, Rosenkranz N, Schuh N, Elvers N, Willoughby M, Zhao X, Gottschalk A. pOpsicle: An all-optical reporter system for synaptic vesicle recycling combining pH-sensitive fluorescent proteins with optogenetic manipulation of neuronal activity. Front Cell Neurosci 2023; 17:1120651. [PMID: 37066081 PMCID: PMC10102542 DOI: 10.3389/fncel.2023.1120651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Accepted: 03/15/2023] [Indexed: 04/03/2023] Open
Abstract
pH-sensitive fluorescent proteins are widely used to study synaptic vesicle (SV) fusion and recycling. When targeted to the lumen of SVs, fluorescence of these proteins is quenched by the acidic pH. Following SV fusion, they are exposed to extracellular neutral pH, resulting in a fluorescence increase. SV fusion, recycling and acidification can thus be tracked by tagging integral SV proteins with pH-sensitive proteins. Neurotransmission is generally activated by electrical stimulation, which is not feasible in small, intact animals. Previous in vivo approaches depended on distinct (sensory) stimuli, thus limiting the addressable neuron types. To overcome these limitations, we established an all-optical approach to stimulate and visualize SV fusion and recycling. We combined distinct pH-sensitive fluorescent proteins (inserted into the SV protein synaptogyrin) and light-gated channelrhodopsins (ChRs) for optical stimulation, overcoming optical crosstalk and thus enabling an all-optical approach. We generated two different variants of the pH-sensitive optogenetic reporter of vesicle recycling (pOpsicle) and tested them in cholinergic neurons of intact Caenorhabditis elegans nematodes. First, we combined the red fluorescent protein pHuji with the blue-light gated ChR2(H134R), and second, the green fluorescent pHluorin combined with the novel red-shifted ChR ChrimsonSA. In both cases, fluorescence increases were observed after optical stimulation. Increase and subsequent decline of fluorescence was affected by mutations of proteins involved in SV fusion and endocytosis. These results establish pOpsicle as a non-invasive, all-optical approach to investigate different steps of the SV cycle.
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Affiliation(s)
- Marius Seidenthal
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
- Institute of Biophysical Chemistry, Department of Biochemistry, Chemistry and Pharmacy, Goethe University, Frankfurt, Germany
| | - Barbara Jánosi
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
- Institute of Biophysical Chemistry, Department of Biochemistry, Chemistry and Pharmacy, Goethe University, Frankfurt, Germany
| | - Nils Rosenkranz
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
- Institute of Biophysical Chemistry, Department of Biochemistry, Chemistry and Pharmacy, Goethe University, Frankfurt, Germany
| | - Noah Schuh
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
- Institute of Biophysical Chemistry, Department of Biochemistry, Chemistry and Pharmacy, Goethe University, Frankfurt, Germany
| | - Nora Elvers
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
- Institute of Biophysical Chemistry, Department of Biochemistry, Chemistry and Pharmacy, Goethe University, Frankfurt, Germany
| | - Miles Willoughby
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
- Institute of Biophysical Chemistry, Department of Biochemistry, Chemistry and Pharmacy, Goethe University, Frankfurt, Germany
| | - Xinda Zhao
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
- Institute of Biophysical Chemistry, Department of Biochemistry, Chemistry and Pharmacy, Goethe University, Frankfurt, Germany
| | - Alexander Gottschalk
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt, Germany
- Institute of Biophysical Chemistry, Department of Biochemistry, Chemistry and Pharmacy, Goethe University, Frankfurt, Germany
- *Correspondence: Alexander Gottschalk,
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3
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Heuser JE. The Structural Basis of Long-Term Potentiation in Hippocampal Synapses, Revealed by Electron Microscopy Imaging of Lanthanum-Induced Synaptic Vesicle Recycling. Front Cell Neurosci 2022; 16:920360. [PMID: 35978856 PMCID: PMC9376242 DOI: 10.3389/fncel.2022.920360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 05/05/2022] [Indexed: 11/29/2022] Open
Abstract
Hippocampal neurons in dissociated cell cultures were exposed to the trivalent cation lanthanum for short periods (15–30 min) and prepared for electron microscopy (EM), to evaluate the stimulatory effects of this cation on synaptic ultrastructure. Not only were characteristic ultrastructural changes of exaggerated synaptic vesicle turnover seen within the presynapses of these cultures—including synaptic vesicle depletion and proliferation of vesicle-recycling structures—but the overall architecture of a large proportion of the synapses in the cultures was dramatically altered, due to large postsynaptic “bulges” or herniations into the presynapses. Moreover, in most cases, these postsynaptic herniations or protrusions produced by lanthanum were seen by EM to distort or break or “perforate” the so-called postsynaptic densities (PSDs) that harbor receptors and recognition molecules essential for synaptic function. These dramatic EM observations lead us to postulate that such PSD breakages or “perforations” could very possibly create essential substrates or “tags” for synaptic growth, simply by creating fragmented free edges around the PSDs, into which new receptors and recognition molecules could be recruited more easily, and thus, they could represent the physical substrate for the important synaptic growth process known as “long-term potentiation” (LTP). All of this was created simply in hippocampal dissociated cell cultures, and simply by pushing synaptic vesicle recycling way beyond its normal limits with the trivalent cation lanthanum, but we argued in this report that such fundamental changes in synaptic architecture—given that they can occur at all—could also occur at the extremes of normal neuronal activity, which are presumed to lead to learning and memory.
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Liang M, Liu H, Yin X, Gong L, Jie H, Wang L, Shi H, He J, Chen P, Lu J, Yin S, Yang J. NAD+ attenuates bilirubin-induced augmentation of voltage-gated calcium currents in neurons of the ventral cochlear nucleus. Neurosci Lett 2022; 784:136747. [PMID: 35724761 DOI: 10.1016/j.neulet.2022.136747] [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: 11/02/2021] [Revised: 04/26/2022] [Accepted: 06/15/2022] [Indexed: 11/30/2022]
Abstract
Nicotinamide adenine dinucleotide (NAD+) is a ubiquitous molecule with wide-ranging roles in several cell processes, such as regulation of calcium homeostasis and protection against cell injuries. However, the roles of NAD+ in neuroprotection is poorly understood. The main neurons in ventral cochlear nucleus (VCN) are highly susceptible to bilirubin-associated excitotoxicity. We investigated the effects of NAD+ on VCN neurons by whole cell patch-clamp recordings. We found that NAD+ effectively reverses and inhibits bilirubin-mediated enhancement of voltage-gated calcium (VGCC) currents in VCN neurons. Moreover, NAD+ itself did not affect VGCC currents. These results collectively suggest that NAD+ may be neuroprotective by attenuating Ca2+ influx to suppress bilirubin-induced intracellular Ca2+ overloads. Our research provides a basis for evaluation of NAD+ as a promising therapeutic target for bilirubin encephalopathy and excitotoxicity associated with other neurological disorders.
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Affiliation(s)
- Min Liang
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Hanwei Liu
- Department of Otorhinolaryngology, the Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Xinlu Yin
- Department of Otorhinolaryngology-Head and Neck Surgery, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Lina Gong
- Department of Otorhinolaryngology, the Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Huiqun Jie
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Luyang Wang
- Program in Neurosciences & Mental Health, SickKids Research Institute
| | - Haibo Shi
- Department of Otorhinolaryngology, the Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Jingchun He
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Penghui Chen
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Jingrong Lu
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Shankai Yin
- Department of Otorhinolaryngology, the Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Jun Yang
- Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
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5
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Laporte MH, Chi KI, Caudal LC, Zhao N, Schwarz Y, Rolland M, Martinez-Hernandez J, Martineau M, Chatellard C, Denarier E, Mercier V, Lemaître F, Blot B, Moutaux E, Cazorla M, Perrais D, Lanté F, Bruns D, Fraboulet S, Hemming FJ, Kirchhoff F, Sadoul R. Alix is required for activity-dependent bulk endocytosis at brain synapses. PLoS Biol 2022; 20:e3001659. [PMID: 35658004 PMCID: PMC9200306 DOI: 10.1371/journal.pbio.3001659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 06/15/2022] [Accepted: 05/04/2022] [Indexed: 12/04/2022] Open
Abstract
In chemical synapses undergoing high frequency stimulation, vesicle components can be retrieved from the plasma membrane via a clathrin-independent process called activity-dependent bulk endocytosis (ADBE). Alix (ALG-2-interacting protein X/PDCD6IP) is an adaptor protein binding to ESCRT and endophilin-A proteins which is required for clathrin-independent endocytosis in fibroblasts. Alix is expressed in neurons and concentrates at synapses during epileptic seizures. Here, we used cultured neurons to show that Alix is recruited to presynapses where it interacts with and concentrates endophilin-A during conditions triggering ADBE. Using Alix knockout (ko) neurons, we showed that this recruitment, which requires interaction with the calcium-binding protein ALG-2, is necessary for ADBE. We also found that presynaptic compartments of Alix ko hippocampi display subtle morphological defects compatible with flawed synaptic activity and plasticity detected electrophysiologically. Furthermore, mice lacking Alix in the forebrain undergo less seizures during kainate-induced status epilepticus and reduced propagation of the epileptiform activity. These results thus show that impairment of ADBE due to the lack of neuronal Alix leads to abnormal synaptic recovery during physiological or pathological repeated stimulations. The adaptor protein Alix (PDCD6IP) is necessary for membrane shaping underlying various biological processes including endocytosis. This study shows that Alix mediates activity-dependent bulk endocytosis and is required for correct synaptic physiology under normal and pathological conditions.
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Affiliation(s)
- Marine H. Laporte
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Department of Cell Biology, University of Geneva, Geneva, Switzerland
- * E-mail: (MHL); (FK); (RS)
| | - Kwang Il Chi
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Laura C. Caudal
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Na Zhao
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Yvonne Schwarz
- Molecular Neurophysiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Marta Rolland
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - José Martinez-Hernandez
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad Castilla-La Mancha, Albacete, Spain
| | - Magalie Martineau
- Interdisciplinary Institute for Neuroscience, University of Bordeaux-CNRS UMR 5297, Bordeaux, France
| | - Christine Chatellard
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Institut de Biologie Structurale, University Grenoble Alpes—CNRS-CEA UMR 5075, Grenoble, France
| | - Eric Denarier
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Vincent Mercier
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Department of Biochemistry, University of Geneva, Geneva, Switzerland
| | - Florent Lemaître
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Département des Neurosciences, Centre de Recherche du centre hospitalier de Montréal, Canada
| | - Béatrice Blot
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Eve Moutaux
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Maxime Cazorla
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Institut de Neuroscience la Timone, CNRS UMR7289, Marseille, France
| | - David Perrais
- Interdisciplinary Institute for Neuroscience, University of Bordeaux-CNRS UMR 5297, Bordeaux, France
| | - Fabien Lanté
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Dieter Bruns
- Molecular Neurophysiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Sandrine Fraboulet
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Institute for Advanced Biosciences, Univ. Grenoble Alpes—INSERM U1209—CNRS UMR 5309, Grenoble, France
| | - Fiona J. Hemming
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
- * E-mail: (MHL); (FK); (RS)
| | - Rémy Sadoul
- Grenoble Institute Neurosciences, University Grenoble Alpes—INSERM U1216—CEA, Grenoble, France
- Institut de Biologie Structurale, University Grenoble Alpes—CNRS-CEA UMR 5075, Grenoble, France
- * E-mail: (MHL); (FK); (RS)
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6
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FMRP Sustains Presynaptic Function via Control of Activity-Dependent Bulk Endocytosis. J Neurosci 2022; 42:1618-1628. [PMID: 34996816 PMCID: PMC8883869 DOI: 10.1523/jneurosci.0852-21.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 12/22/2021] [Accepted: 12/23/2021] [Indexed: 11/21/2022] Open
Abstract
Synaptic vesicle (SV) recycling is essential for the maintenance of neurotransmission, with a number of neurodevelopmental disorders linked to defects in this process. Fragile X syndrome (FXS) results from a loss of fragile X mental retardation protein (FMRP) encoded by the FMR1 gene. Hyperexcitability of neuronal circuits is a key feature of FXS, therefore we investigated whether SV recycling was affected by the absence of FMRP during increased neuronal activity. We revealed that primary neuronal cultures from male Fmr1 knock-out (KO) rats display a specific defect in activity-dependent bulk endocytosis (ADBE). ADBE is dominant during intense neuronal activity, and this defect resulted in an inability of Fmr1 KO neurons to sustain SV recycling during trains of high-frequency stimulation. Using a molecular replacement strategy, we also revealed that a human FMRP mutant that cannot bind BK channels failed to correct ADBE dysfunction in KO neurons, however this dysfunction was corrected by BK channel agonists. Therefore, FMRP performs a key role in sustaining neurotransmitter release via selective control of ADBE, suggesting intervention via this endocytosis mode may correct the hyperexcitability observed in FXS.SIGNIFICANCE STATEMENT Loss of fragile X mental retardation protein (FMRP) results in fragile X syndrome (FXS), however whether its loss has a direct role in neurotransmitter release remains a matter of debate. We demonstrate that neurons lacking FMRP display a specific defect in a mechanism that sustains neurotransmitter release during intense neuronal firing, called activity-dependent bulk endocytosis (ADBE). This discovery provides key insights into mechanisms of brain communication that occur because of loss of FMRP function. Importantly it also reveals ADBE as a potential therapeutic target to correct the circuit hyperexcitability observed in FXS.
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7
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Clathrin-mediated endocytosis cooperates with bulk endocytosis to generate vesicles. iScience 2022; 25:103809. [PMID: 35198874 PMCID: PMC8841809 DOI: 10.1016/j.isci.2022.103809] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 06/02/2021] [Accepted: 01/20/2022] [Indexed: 11/25/2022] Open
Abstract
Clathrin-mediated endocytosis, the most prominent endocytic mode, is thought to be generated primarily from relatively flat patches of the plasma membrane. By employing conventional and platinum replica electron microscopy and super-resolution STED microscopy in neuroendocrine chromaffin cells, we found that large Ω-shaped or dome-shaped plasma membrane invaginations, previously thought of as the precursor of bulk endocytosis, are primary sites for clathrin-coated pit generation after depolarization. Clathrin-coated pits are more densely packed at invaginations rather than flat membranes, suggesting that invaginations are preferred sites for clathrin-coated pit formation, likely because their positive curvature facilitates coated-pit formation. Thus, clathrin-mediated endocytosis closely collaborates with bulk endocytosis to enhance endocytic capacity in active secretory cells. This direct collaboration between two classically independent endocytic pathways is of broad importance given the central role of both clathrin-mediated endocytosis and bulk endocytosis in neurons, endocrine cells, immune cells, and many other cell types throughout the body. Bulk membrane invaginations are primary sites for clathrin-coated pit formation Invaginations are preferred over flat membrane for clathrin-coated pit formation Clathrin-coated vesicle formation from membrane invagination is suggested Clathrin-mediated and bulk endocytosis collaborate to enhance endocytic capacity
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8
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Luo JK, Melland H, Nithianantharajah J, Gordon SL. Postsynaptic Neuroligin-1 Mediates Presynaptic Endocytosis During Neuronal Activity. Front Mol Neurosci 2021; 14:744845. [PMID: 34690694 PMCID: PMC8531268 DOI: 10.3389/fnmol.2021.744845] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 09/15/2021] [Indexed: 01/31/2023] Open
Abstract
Fast, high-fidelity neurotransmission and synaptic efficacy requires tightly regulated coordination of pre- and postsynaptic compartments and alignment of presynaptic release sites with postsynaptic receptor nanodomains. Neuroligin-1 (Nlgn1) is a postsynaptic cell-adhesion protein exclusively localised to excitatory synapses that is crucial for coordinating the transsynaptic alignment of presynaptic release sites with postsynaptic AMPA receptors as well as postsynaptic transmission and plasticity. However, little is understood about whether the postsynaptic machinery can mediate the molecular architecture and activity of the presynaptic nerve terminal, and thus it remains unclear whether there are presynaptic contributions to Nlgn1-dependent control of signalling and plasticity. Here, we employed a presynaptic reporter of neurotransmitter release and synaptic vesicle dynamics, synaptophysin-pHluorin (sypHy), to directly assess the presynaptic impact of loss of Nlgn1. We show that lack of Nlgn1 had no effect on the size of the readily releasable or entire recycling pool of synaptic vesicles, nor did it impact exocytosis. However, we observed significant changes in the retrieval of synaptic vesicles by compensatory endocytosis, specifically during activity. Our data extends growing evidence that synaptic adhesion molecules critical for forming transsynaptic scaffolds are also important for regulating activity-induced endocytosis at the presynapse.
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Affiliation(s)
- Jiaqi Keith Luo
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Holly Melland
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia.,Melbourne Dementia Research Centre, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Jess Nithianantharajah
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Sarah L Gordon
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia.,Melbourne Dementia Research Centre, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
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9
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James OG, Selvaraj BT, Magnani D, Burr K, Connick P, Barton SK, Vasistha NA, Hampton DW, Story D, Smigiel R, Ploski R, Brophy PJ, Ffrench-Constant C, Lyons DA, Chandran S. iPSC-derived myelinoids to study myelin biology of humans. Dev Cell 2021; 56:1346-1358.e6. [PMID: 33945785 PMCID: PMC8098746 DOI: 10.1016/j.devcel.2021.04.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 01/20/2021] [Accepted: 04/06/2021] [Indexed: 01/03/2023]
Abstract
Myelination is essential for central nervous system (CNS) formation, health, and function. Emerging evidence of oligodendrocyte heterogeneity in health and disease and divergent CNS gene expression profiles between mice and humans supports the development of experimentally tractable human myelination systems. Here, we developed human iPSC-derived myelinating organoids ("myelinoids") and quantitative tools to study myelination from oligodendrogenesis through to compact myelin formation and myelinated axon organization. Using patient-derived cells, we modeled a monogenetic disease of myelinated axons (Nfasc155 deficiency), recapitulating impaired paranodal axo-glial junction formation. We also validated the use of myelinoids for pharmacological assessment of myelination-both at the level of individual oligodendrocytes and globally across whole myelinoids-and demonstrated reduced myelination in response to suppressed synaptic vesicle release. Our study provides a platform to investigate human myelin development, disease, and adaptive myelination.
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Affiliation(s)
- Owen G James
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK; Anne Rowling Regenerative Neurology Clinic, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Bhuvaneish T Selvaraj
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Dario Magnani
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Karen Burr
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Peter Connick
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Anne Rowling Regenerative Neurology Clinic, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Samantha K Barton
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK; Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia
| | - Navneet A Vasistha
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK; Biotech Research and Innovation Centre, Copenhagen N 2200, Denmark
| | - David W Hampton
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK
| | - David Story
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Robert Smigiel
- Department of Pediatrics and Rare Disorders, Wroclaw Medical University, Wrocław 51-618, Poland
| | - Rafal Ploski
- Department of Medical Genetics, Medical University of Warsaw, Warsaw 02-106, Poland
| | - Peter J Brophy
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
| | | | - David A Lyons
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Siddharthan Chandran
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh EH16 4SB, UK; Anne Rowling Regenerative Neurology Clinic, University of Edinburgh, Edinburgh EH16 4SB, UK; Centre for Brain Development and Repair, inStem, Bangalore 560065, India.
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10
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Morgan AJ, Davis LC, Galione A. Choreographing endo-lysosomal Ca 2+ throughout the life of a phagosome. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:119040. [PMID: 33872669 DOI: 10.1016/j.bbamcr.2021.119040] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 04/05/2021] [Accepted: 04/07/2021] [Indexed: 12/20/2022]
Abstract
The emergence of endo-lysosomes as ubiquitous Ca2+ stores with their unique cohort of channels has resulted in their being implicated in a growing number of processes in an ever-increasing number of cell types. The architectural and regulatory constraints of these acidic Ca2+ stores distinguishes them from other larger Ca2+ sources such as the ER and influx across the plasma membrane. In view of recent advances in the understanding of the modes of operation, we discuss phagocytosis as a template for how endo-lysosomal Ca2+ signals (generated via TPC and TRPML channels) can be integrated in multiple sophisticated ways into biological processes. Phagocytosis illustrates how different endo-lysosomal Ca2+ signals drive different phases of a process, and how these can be altered by disease or infection.
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Affiliation(s)
- Anthony J Morgan
- Department of Pharmacology, University of Oxford, Mansfield Park, Oxford OX1 3QT, UK.
| | - Lianne C Davis
- Department of Pharmacology, University of Oxford, Mansfield Park, Oxford OX1 3QT, UK
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Mansfield Park, Oxford OX1 3QT, UK.
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11
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Li TN, Chen YJ, Lu TY, Wang YT, Lin HC, Yao CK. A positive feedback loop between Flower and PI(4,5)P 2 at periactive zones controls bulk endocytosis in Drosophila. eLife 2020; 9:60125. [PMID: 33300871 PMCID: PMC7748424 DOI: 10.7554/elife.60125] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 12/09/2020] [Indexed: 01/01/2023] Open
Abstract
Synaptic vesicle (SV) endocytosis is coupled to exocytosis to maintain SV pool size and thus neurotransmitter release. Intense stimulation induces activity-dependent bulk endocytosis (ADBE) to recapture large quantities of SV constituents in large endosomes from which SVs reform. How these consecutive processes are spatiotemporally coordinated remains unknown. Here, we show that Flower Ca2+ channel-dependent phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) compartmentalization governs control of these processes in Drosophila. Strong stimuli trigger PI(4,5)P2 microdomain formation at periactive zones. Upon exocytosis, Flower translocates from SVs to periactive zones, where it increases PI(4,5)P2 levels via Ca2+ influxes. Remarkably, PI(4,5)P2 directly enhances Flower channel activity, thereby establishing a positive feedback loop for PI(4,5)P2 microdomain compartmentalization. PI(4,5)P2 microdomains drive ADBE and SV reformation from bulk endosomes. PI(4,5)P2 further retrieves Flower to bulk endosomes, terminating endocytosis. We propose that the interplay between Flower and PI(4,5)P2 is the crucial spatiotemporal cue that couples exocytosis to ADBE and subsequent SV reformation.
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Affiliation(s)
- Tsai-Ning Li
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Yu-Jung Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Ting-Yi Lu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - You-Tung Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Hsin-Chieh Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Chi-Kuang Yao
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.,Neuroscience Program of Academia Sinica, Academia Sinica, Taipei, Taiwan.,Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
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12
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Cheung G, Cousin MA. Synaptic vesicle generation from activity-dependent bulk endosomes requires a dephosphorylation-dependent dynamin-syndapin interaction. J Neurochem 2019; 151:570-583. [PMID: 31479508 PMCID: PMC6899846 DOI: 10.1111/jnc.14862] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 07/24/2019] [Accepted: 08/28/2019] [Indexed: 12/13/2022]
Abstract
Activity‐dependent bulk endocytosis generates synaptic vesicles (SVs) during intense neuronal activity via a two‐step process. First, bulk endosomes are formed direct from the plasma membrane from which SVs are then generated. SV generation from bulk endosomes requires the efflux of previously accumulated calcium and activation of the protein phosphatase calcineurin. However, it is still unknown how calcineurin mediates SV generation. We addressed this question using a series of acute interventions that decoupled the generation of SVs from bulk endosomes in rat primary neuronal culture. This was achieved by either disruption of protein–protein interactions via delivery of competitive peptides, or inhibition of enzyme activity by known inhibitors. SV generation was monitored using either a morphological horseradish peroxidase assay or an optical assay that monitors the replenishment of the reserve SV pool. We found that SV generation was inhibited by, (i) peptides that disrupt calcineurin interactions, (ii) an inhibitor of dynamin I GTPase activity and (iii) peptides that disrupt the phosphorylation‐dependent dynamin I–syndapin I interaction. Peptides that disrupted syndapin I interactions with eps15 homology domain‐containing proteins had no effect. This revealed that (i) calcineurin must be localized at bulk endosomes to mediate its effect, (ii) dynamin I GTPase activity is essential for SV fission and (iii) the calcineurin‐dependent interaction between dynamin I and syndapin I is essential for SV generation. We therefore propose that a calcineurin‐dependent dephosphorylation cascade that requires both dynamin I GTPase and syndapin I lipid‐deforming activity is essential for SV generation from bulk endosomes. ![]()
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Affiliation(s)
- Giselle Cheung
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK.,Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, UK
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13
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Activity-dependent bulk endocytosis proteome reveals a key presynaptic role for the monomeric GTPase Rab11. Proc Natl Acad Sci U S A 2018; 115:E10177-E10186. [PMID: 30301801 PMCID: PMC6205440 DOI: 10.1073/pnas.1809189115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The maintenance of neurotransmission by synaptic vesicle (SV) recycling is critical to brain function. The dominant SV recycling mode during intense activity is activity-dependent bulk endocytosis (ADBE), suggesting it will perform a pivotal role in neurotransmission. However, the role of ADBE is still undetermined, due to the absence of identified molecules specific for this process. The determination of the bulk endosome proteome (a key ADBE organelle) revealed that it has a unique molecular signature and identified a role for Rab11 in presynaptic function. This work provides the molecular inventory of ADBE, a resource that will be of significant value to researchers wishing to modulate neurotransmission during intense neuronal activity in both health and disease. Activity-dependent bulk endocytosis (ADBE) is the dominant mode of synaptic vesicle endocytosis during high-frequency stimulation, suggesting it should play key roles in neurotransmission during periods of intense neuronal activity. However, efforts in elucidating the physiological role of ADBE have been hampered by the lack of identified molecules which are unique to this endocytosis mode. To address this, we performed proteomic analysis on purified bulk endosomes, which are a key organelle in ADBE. Bulk endosomes were enriched via two independent approaches, a classical subcellular fractionation method and isolation via magnetic nanoparticles. There was a 77% overlap in proteins identified via the two protocols, and these molecules formed the ADBE core proteome. Bioinformatic analysis revealed a strong enrichment in cell adhesion and cytoskeletal and signaling molecules, in addition to expected synaptic and trafficking proteins. Network analysis identified Rab GTPases as a central hub within the ADBE proteome. Subsequent investigation of a subset of these Rabs revealed that Rab11 both facilitated ADBE and accelerated clathrin-mediated endocytosis. These findings suggest that the ADBE proteome will provide a rich resource for the future study of presynaptic function, and identify Rab11 as a regulator of presynaptic function.
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14
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Yao CK, Liu YT, Lee IC, Wang YT, Wu PY. A Ca2+ channel differentially regulates Clathrin-mediated and activity-dependent bulk endocytosis. PLoS Biol 2017; 15:e2000931. [PMID: 28414717 PMCID: PMC5393565 DOI: 10.1371/journal.pbio.2000931] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 03/21/2017] [Indexed: 11/19/2022] Open
Abstract
Clathrin-mediated endocytosis (CME) and activity-dependent bulk endocytosis (ADBE) are two predominant forms of synaptic vesicle (SV) endocytosis, elicited by moderate and strong stimuli, respectively. They are tightly coupled with exocytosis for sustained neurotransmission. However, the underlying mechanisms are ill defined. We previously reported that the Flower (Fwe) Ca2+ channel present in SVs is incorporated into the periactive zone upon SV fusion, where it triggers CME, thus coupling exocytosis to CME. Here, we show that Fwe also promotes ADBE. Intriguingly, the effects of Fwe on CME and ADBE depend on the strength of the stimulus. Upon mild stimulation, Fwe controls CME independently of Ca2+ channeling. However, upon strong stimulation, Fwe triggers a Ca2+ influx that initiates ADBE. Moreover, knockout of rodent fwe in cultured rat hippocampal neurons impairs but does not completely abolish CME, similar to the loss of Drosophila fwe at the neuromuscular junction, suggesting that Fwe plays a regulatory role in regulating CME across species. In addition, the function of Fwe in ADBE is conserved at mammalian central synapses. Hence, Fwe exerts different effects in response to different stimulus strengths to control two major modes of endocytosis.
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Affiliation(s)
- Chi-Kuang Yao
- Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei, Taiwan
- Neuroscience Program in Academia Sinica, Academia Sinica, Nankang, Taipei, Taiwan
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei, Taiwan
- * E-mail:
| | - Yu-Tzu Liu
- Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei, Taiwan
| | - I-Chi Lee
- Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei, Taiwan
| | - You-Tung Wang
- Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei, Taiwan
| | - Ping-Yen Wu
- Institute of Biological Chemistry, Academia Sinica, Nankang, Taipei, Taiwan
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