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Wernert F, Moparthi SB, Pelletier F, Lainé J, Simons E, Moulay G, Rueda F, Jullien N, Benkhelifa-Ziyyat S, Papandréou MJ, Leterrier C, Vassilopoulos S. The actin-spectrin submembrane scaffold restricts endocytosis along proximal axons. Science 2024; 385:eado2032. [PMID: 39172837 DOI: 10.1126/science.ado2032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 06/24/2024] [Indexed: 08/24/2024]
Abstract
Clathrin-mediated endocytosis has characteristic features in neuronal dendrites and presynapses, but how membrane proteins are internalized along the axon shaft remains unclear. We focused on clathrin-coated structures and endocytosis along the axon initial segment (AIS) and their relationship to the periodic actin-spectrin scaffold that lines the axonal plasma membrane. A combination of super-resolution microscopy and platinum-replica electron microscopy on cultured neurons revealed that AIS clathrin-coated pits form within "clearings", circular areas devoid of actin-spectrin mesh. Actin-spectrin scaffold disorganization increased clathrin-coated pit formation. Cargo uptake and live-cell imaging showed that AIS clathrin-coated pits are particularly stable. Neuronal plasticity-inducing stimulation triggered internalization of the clathrin-coated pits through polymerization of branched actin around them. Thus, spectrin and actin regulate clathrin-coated pit formation and scission to control endocytosis at the AIS.
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Affiliation(s)
- Florian Wernert
- Aix Marseille Université, CNRS, INP UMR7051, NeuroCyto, 13005 Marseille, France
| | - Satish Babu Moparthi
- Sorbonne Université, INSERM, Institute of Myology, Centre of Research in Myology, UMRS 974, Paris, France
| | - Florence Pelletier
- Aix Marseille Université, CNRS, INP UMR7051, NeuroCyto, 13005 Marseille, France
| | - Jeanne Lainé
- Sorbonne Université, Department of Physiology, Faculty of Medicine Pitié-Salpêtrière, Paris, France
| | - Eline Simons
- Aix Marseille Université, CNRS, INP UMR7051, NeuroCyto, 13005 Marseille, France
| | - Gilles Moulay
- Sorbonne Université, INSERM, Institute of Myology, Centre of Research in Myology, UMRS 974, Paris, France
| | - Fanny Rueda
- Aix Marseille Université, CNRS, INP UMR7051, NeuroCyto, 13005 Marseille, France
| | - Nicolas Jullien
- Aix Marseille Université, CNRS, INP UMR7051, NeuroCyto, 13005 Marseille, France
| | - Sofia Benkhelifa-Ziyyat
- Sorbonne Université, INSERM, Institute of Myology, Centre of Research in Myology, UMRS 974, Paris, France
| | | | | | - Stéphane Vassilopoulos
- Sorbonne Université, INSERM, Institute of Myology, Centre of Research in Myology, UMRS 974, Paris, France
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2
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Griffin H, Hanson J, Phelan KD, Baldini G. MC4R Localizes at Excitatory Postsynaptic and Peri-Postsynaptic Sites of Hypothalamic Neurons in Primary Culture. Cells 2024; 13:1235. [PMID: 39120267 PMCID: PMC11311852 DOI: 10.3390/cells13151235] [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: 04/28/2024] [Revised: 07/13/2024] [Accepted: 07/18/2024] [Indexed: 08/10/2024] Open
Abstract
The melanocortin-4 receptor (MC4R) is a G protein-coupled receptor (GPCR) that is expressed in several brain locations encompassing the hypothalamus and the brainstem, where the receptor controls several body functions, including metabolism. In a well-defined pathway to decrease appetite, hypothalamic proopiomelanocortin (POMC) neurons localized in the arcuate nucleus (Arc) project to MC4R neurons in the paraventricular nuclei (PVN) to release the natural MC4R agonist α-melanocyte-stimulating hormone (α-MSH). Arc neurons also project excitatory glutamatergic fibers to the MC4R neurons in the PVN for a fast synaptic transmission to regulate a satiety pathway potentiated by α-MSH. By using super-resolution microscopy, we found that in hypothalamic neurons in a primary culture, postsynaptic density protein 95 (PSD95) colocalizes with GluN1, a subunit of the ionotropic N-methyl-D-aspartate receptor (NMDAR). Thus, hypothalamic neurons form excitatory postsynaptic specializations. To study the MC4R distribution at these sites, tagged HA-MC4R under the synapsin promoter was expressed in neurons by adeno-associated virus (AAV) gene transduction. HA-MC4R immunofluorescence peaked at the center and in proximity to the PSD95- and NMDAR-expressing sites. These data provide morphological evidence that MC4R localizes together with glutamate receptors at postsynaptic and peri-postsynaptic sites.
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Affiliation(s)
- Haven Griffin
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (H.G.); (J.H.)
| | - Jude Hanson
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (H.G.); (J.H.)
| | - Kevin D. Phelan
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA;
| | - Giulia Baldini
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (H.G.); (J.H.)
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3
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Gupta S, Tielemans A, Guevara CA, Huntley GW, Benson DL. Parkinson's-linked LRRK2-G2019S derails AMPAR trafficking, mobility, and composition in striatum with cell-type and subunit specificity. Proc Natl Acad Sci U S A 2024; 121:e2317833121. [PMID: 38968112 PMCID: PMC11252801 DOI: 10.1073/pnas.2317833121] [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: 10/22/2023] [Accepted: 05/27/2024] [Indexed: 07/07/2024] Open
Abstract
Parkinson's disease (PD) is a multifactorial disease that affects multiple brain systems and circuits. While defined by motor symptoms caused by degeneration of brainstem dopamine neurons, debilitating non-motor abnormalities in fronto-striatal-based cognitive function are common, appear early, and are initially independent of dopamine. Young adult mice expressing the PD-associated G2019S missense mutation in Lrrk2 also exhibit deficits in fronto-striatal-based cognitive tasks. In mice and humans, cognitive functions require dynamic adjustments in glutamatergic synapse strength through cell-surface trafficking of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type glutamate receptors (AMPARs), but it is unknown how LRRK2 mutation impacts dynamic features of AMPAR trafficking in striatal projection neurons (SPNs). Here, we used Lrrk2G2019S knockin mice to show that surface AMPAR subunit stoichiometry is altered biochemically and functionally in mutant SPNs in dorsomedial striatum to favor the incorporation of GluA1 over GluA2. GluA1-containing AMPARs were resistant to internalization from the cell surface, leaving an excessive accumulation of GluA1 on the surface within and outside synapses. This negatively impacted trafficking dynamics that normally support synapse strengthening, as GluA1-containing AMPARs failed to increase at synapses in response to a potentiating stimulus and showed significantly reduced surface mobility. Surface GluA2-containing AMPARs were expressed at normal levels in synapses, indicating subunit-selective impairment. Abnormal surface accumulation of GluA1 was independent of PKA activity and was limited to D1R SPNs. Since LRRK2 mutation is thought to be part of a common PD pathogenic pathway, our data suggest that sustained, striatal cell-type specific changes in AMPAR composition and trafficking contribute to cognitive or other impairments associated with PD.
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Affiliation(s)
- Swati Gupta
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | - Alexander Tielemans
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | - Christopher A. Guevara
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | - George W. Huntley
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | - Deanna L. Benson
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY10029
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4
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Sun C. Single-Molecule-Resolution Approaches in Synaptic Biology. J Phys Chem B 2024; 128:3061-3068. [PMID: 38513216 DOI: 10.1021/acs.jpcb.3c08026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
Synapses between neurons are the primary loci for information transfer and storage in the brain. An individual neuron, alone, can make over 10000 synaptic contacts. It is, however, not easy to investigate what goes on locally within a synapse because many synaptic compartments are only a few hundred nanometers wide in size─close to the diffraction limit of light. To observe the biomolecular machinery and processes within synapses, in situ single-molecule techniques are emerging as powerful tools. Guided by important biological questions, this Perspective will highlight recent advances in using these techniques to obtain in situ measurements of synaptic molecules in three aspects: the cell-biological machinery within synapses, the synaptic architecture, and the synaptic neurotransmitter receptors. These advances showcase the increasing importance of single-molecule-resolution techniques for accessing subcellular biophysical and biomolecular information related to the brain.
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Affiliation(s)
- Chao Sun
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, 8000 Aarhus C, Denmark
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5
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Zhang P, Li J, Li W, Qiao S, Ou Y, Yuan X. Synaptic endocytosis in adult adipose stromal cell-derived neurons. Brain Res 2024; 1827:148746. [PMID: 38184164 DOI: 10.1016/j.brainres.2023.148746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 12/24/2023] [Accepted: 12/30/2023] [Indexed: 01/08/2024]
Abstract
Synapses are essential for facilitating the transmission of information between neurons and for executing neurophysiological processes. Following the exocytosis of neurotransmitters, the synaptic vesicle may quickly undergo endocytosis to preserve the structural integrity of the synapse. When converting adipose-derived stromal cells (ADSCs) into neurons, the ADSCs have already demonstrated comparable morphology, structure, and electrophysiological characteristics to neurons. Nevertheless, there is currently no published study on the endocytotic function of neurons that are produced from ADSCs. This study aimed to examine synaptic endocytosis in neurons derived from ADSCs by qualitatively and quantitatively analyzing the presence of Ap-2, Clathrin, Endophilin, Dynamin, and Hsc70, which are the key proteins involved in clathrin-mediated endocytosis (CME), as well as by using FM1-43 and cadmium selenide quantum dots (CdSe QDs). Additionally, single-cell RNA sequencing (scRNA-seq) was used to look at the levels of both neuronal markers and markers related to CME at the same time. The results of this study provide evidence that synapses in neurons produced from ADSCs have a role in endocytosis, mainly through the CME route.
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Affiliation(s)
- Pingshu Zhang
- Department of Neurology, Kailuan General Hospital, North China University of Science and Technology, Tangshan, China; Neurobiology Key Laboratory of HeBei, Tangshan, China
| | - Jing Li
- Radiology Department of Tangshan Maternal and Child Health Hospital, Tangshan City, Hebei Province, China
| | - Wen Li
- Department of Neurology, Kailuan General Hospital, North China University of Science and Technology, Tangshan, China; Neurobiology Key Laboratory of HeBei, Tangshan, China
| | - Sijia Qiao
- Department of Neurology, Kailuan General Hospital, North China University of Science and Technology, Tangshan, China; Neurobiology Key Laboratory of HeBei, Tangshan, China
| | - Ya Ou
- Department of Neurology, Kailuan General Hospital, North China University of Science and Technology, Tangshan, China; Neurobiology Key Laboratory of HeBei, Tangshan, China
| | - Xiaodong Yuan
- Department of Neurology, Kailuan General Hospital, North China University of Science and Technology, Tangshan, China; Neurobiology Key Laboratory of HeBei, Tangshan, China.
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6
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Nicolaou K, Mulder BM. A probabilistic algorithm for optimising the steady-state diffusional flux into a partially absorbing body. Sci Rep 2023; 13:22815. [PMID: 38129494 PMCID: PMC10739912 DOI: 10.1038/s41598-023-49566-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 12/09/2023] [Indexed: 12/23/2023] Open
Abstract
Cells in an aqueous environment absorb diffusing nutrient molecules through nanoscale protein channels in their outer membranes. Assuming that there are constraints on the number of such channels a cell can produce, we ask the question: given a nondepleting source of nutrients, what is the optimal distribution of these channels over the cell surface? We coarse-grain this problem, phrasing it as a diffusion problem with position-dependent Robin boundary conditions on the surface. The aim is to maximize the steady-state total flux through the partially absorbing surface under an integral constraint on the local reactivities. We develop an algorithm to tackle this problem that uses the stored and processed results of a particle-based simulation with reflective boundary conditions to a posteriori estimate absorption flux at essentially negligible additional computational cost. We validate the algorithm against a few cases for which analytical or semi-analytical results are available. We apply it to two examples: a spherical cell in the presence of a point source and a spheroidal cell with an isotropic source at infinity. In the former case, there is a significant gain relative to the homogeneous case, while in the latter case the gain is only [Formula: see text].
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Affiliation(s)
- Kyriacos Nicolaou
- Institute AMOLF, Science Park 104, 1098XG, Amsterdam, The Netherlands
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Bela M Mulder
- Institute AMOLF, Science Park 104, 1098XG, Amsterdam, The Netherlands.
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands.
- Institute for Theoretical Physics, Utrecht University, Utrecht, The Netherlands.
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7
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Gupta S, Guevara CA, Tielemans A, Huntley GW, Benson DL. Parkinson's-linked LRRK2-G2019S derails AMPAR trafficking, mobility and composition in striatum with cell-type and subunit specificity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.13.562231. [PMID: 37905106 PMCID: PMC10614818 DOI: 10.1101/2023.10.13.562231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Parkinson's (PD) is a multi-factorial disease that affects multiple brain systems and circuits. While defined by motor symptoms caused by degeneration of brainstem dopamine neurons, debilitating non-motor abnormalities in fronto-striatal based cognitive function are common, appear early and are initially independent of dopamine. Young adult mice expressing the PD-associated G2019S missense mutation in Lrrk2 also exhibit deficits in fronto-striatal-based cognitive tasks. In mice and humans, cognitive functions require dynamic adjustments in glutamatergic synapse strength through cell-surface trafficking of AMPA-type glutamate receptors (AMPARs), but it is unknown how LRRK2 mutation impacts dynamic features of AMPAR trafficking in striatal projection neurons (SPNs). Here, we used Lrrk2 G2019S knockin mice to show that surface AMPAR subunit stoichiometry is altered biochemically and functionally in mutant SPNs to favor incorporation of GluA1 over GluA2. GluA1-containing AMPARs were resistant to internalization from the cell surface, leaving an excessive accumulation of GluA1 on the surface within and outside synapses. This negatively impacted trafficking dynamics that normally support synapse strengthening, as GluA1-containing AMPARs failed to increase at synapses in response to a potentiating stimulus and showed significantly reduced surface mobility. Surface GluA2-containing AMPARs were expressed at normal levels in synapses, indicating subunit-selective impairment. Abnormal surface accumulation of GluA1 was independent of PKA activity and was limited to D 1 R SPNs. Since LRRK2 mutation is thought to be part of a common PD pathogenic pathway, our data suggest that sustained, striatal cell-type specific changes in AMPAR composition and trafficking contribute to cognitive or other impairments associated with PD. SIGNIFICANCE STATEMENT Mutations in LRRK2 are common genetic risks for PD. Lrrk2 G2019S mice fail to exhibit long-term potentiation at corticostriatal synapses and show significant deficits in frontal-striatal based cognitive tasks. While LRRK2 has been implicated generally in protein trafficking, whether G2019S derails AMPAR trafficking at synapses on striatal neurons (SPNs) is unknown. We show that surface GluA1-AMPARs fail to internalize and instead accumulate excessively within and outside synapses. This effect is selective to D 1 R SPNs and negatively impacts synapse strengthening as GluA1-AMPARs fail to increase at the surface in response to potentiation and show limited surface mobility. Thus, LRRK2-G2019S narrows the effective range of plasticity mechanisms, supporting the idea that cognitive symptoms reflect an imbalance in AMPAR trafficking mechanisms within cell-type specific projections.
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8
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Fréal A, Jamann N, Ten Bos J, Jansen J, Petersen N, Ligthart T, Hoogenraad CC, Kole MH. Sodium channel endocytosis drives axon initial segment plasticity. SCIENCE ADVANCES 2023; 9:eadf3885. [PMID: 37713493 PMCID: PMC10881073 DOI: 10.1126/sciadv.adf3885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 08/15/2023] [Indexed: 09/17/2023]
Abstract
Activity-dependent plasticity of the axon initial segment (AIS) endows neurons with the ability to adapt action potential output to changes in network activity. Action potential initiation at the AIS highly depends on the clustering of voltage-gated sodium channels, but the molecular mechanisms regulating their plasticity remain largely unknown. Here, we developed genetic tools to label endogenous sodium channels and their scaffolding protein, to reveal their nanoscale organization and longitudinally image AIS plasticity in hippocampal neurons in slices and primary cultures. We find that N-methyl-d-aspartate receptor activation causes both long-term synaptic depression and rapid internalization of AIS sodium channels within minutes. The clathrin-mediated endocytosis of sodium channels at the distal AIS increases the threshold for action potential generation. These data reveal a fundamental mechanism for rapid activity-dependent AIS reorganization and suggests that plasticity of intrinsic excitability shares conserved features with synaptic plasticity.
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Affiliation(s)
- Amélie Fréal
- Axonal Signaling Group, Netherlands Institute for Neurosciences (NIN), Royal Netherlands Academy for Arts and Sciences (KNAW), Amsterdam, Netherlands
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Nora Jamann
- Axonal Signaling Group, Netherlands Institute for Neurosciences (NIN), Royal Netherlands Academy for Arts and Sciences (KNAW), Amsterdam, Netherlands
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Jolijn Ten Bos
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Jacqueline Jansen
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Naomi Petersen
- Axonal Signaling Group, Netherlands Institute for Neurosciences (NIN), Royal Netherlands Academy for Arts and Sciences (KNAW), Amsterdam, Netherlands
| | - Thijmen Ligthart
- Axonal Signaling Group, Netherlands Institute for Neurosciences (NIN), Royal Netherlands Academy for Arts and Sciences (KNAW), Amsterdam, Netherlands
| | - Casper C. Hoogenraad
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
- Department of Neuroscience, Genentech Inc, South San Francisco, CA, USA
| | - Maarten H. P. Kole
- Axonal Signaling Group, Netherlands Institute for Neurosciences (NIN), Royal Netherlands Academy for Arts and Sciences (KNAW), Amsterdam, Netherlands
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
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9
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mGluR5 is transiently confined in perisynaptic nanodomains to shape synaptic function. Nat Commun 2023; 14:244. [PMID: 36646691 PMCID: PMC9842668 DOI: 10.1038/s41467-022-35680-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 12/19/2022] [Indexed: 01/18/2023] Open
Abstract
The unique perisynaptic distribution of postsynaptic metabotropic glutamate receptors (mGluRs) at excitatory synapses is predicted to directly shape synaptic function, but mechanistic insight into how this distribution is regulated and impacts synaptic signaling is lacking. We used live-cell and super-resolution imaging approaches, and developed molecular tools to resolve and acutely manipulate the dynamic nanoscale distribution of mGluR5. Here we show that mGluR5 is dynamically organized in perisynaptic nanodomains that localize close to, but not in the synapse. The C-terminal domain of mGluR5 critically controlled perisynaptic confinement and prevented synaptic entry. We developed an inducible interaction system to overcome synaptic exclusion of mGluR5 and investigate the impact on synaptic function. We found that mGluR5 recruitment to the synapse acutely increased synaptic calcium responses. Altogether, we propose that transient confinement of mGluR5 in perisynaptic nanodomains allows flexible modulation of synaptic function.
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10
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Mougios N, Opazo F, Rizzoli SO, Reshetniak S. Trafficking proteins show limited differences in mobility across different postsynaptic spines. iScience 2023; 26:105971. [PMID: 36718370 PMCID: PMC9883188 DOI: 10.1016/j.isci.2023.105971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 11/24/2022] [Accepted: 01/10/2023] [Indexed: 01/14/2023] Open
Abstract
The function of the postsynaptic compartment is based on the presence and activity of postsynaptic receptors, whose dynamics are controlled by numerous scaffolding, signaling and trafficking proteins. Although the receptors and the scaffolding proteins have received substantial attention, the trafficking proteins have not been investigated extensively. Their mobility rates are unknown, and it is unclear how the postsynaptic environment affects their dynamics. To address this, we analyzed several trafficking proteins (α-synuclein, amphiphysin, calmodulin, doc2a, dynamin, and endophilin), estimating their movement rates in the dendritic shaft, as well as in morphologically distinct "mushroom" and "stubby" postsynapse types. The diffusion parameters were surprisingly similar across dendritic compartments, and a few differences between proteins became evident only in the presence of a synapse neck. We conclude that the movement of trafficking proteins is not strongly affected by the postsynaptic compartment, in stark contrast to the presynapse, which regulates strongly the movement of such proteins.
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Affiliation(s)
- Nikolaos Mougios
- Institute of Neuro- and Sensory Physiology, University Medical Center Göttingen, 37073 Göttingen, Germany,Center for Biostructural Imaging of Neurodegeneration (BIN), University of Göttingen Medical Center, 37075 Göttingen, Germany
| | - Felipe Opazo
- Institute of Neuro- and Sensory Physiology, University Medical Center Göttingen, 37073 Göttingen, Germany,Center for Biostructural Imaging of Neurodegeneration (BIN), University of Göttingen Medical Center, 37075 Göttingen, Germany,NanoTag Biotechnologies GmbH, Göttingen, Germany
| | - Silvio O. Rizzoli
- Institute of Neuro- and Sensory Physiology, University Medical Center Göttingen, 37073 Göttingen, Germany,Center for Biostructural Imaging of Neurodegeneration (BIN), University of Göttingen Medical Center, 37075 Göttingen, Germany,Corresponding author
| | - Sofiia Reshetniak
- Institute of Neuro- and Sensory Physiology, University Medical Center Göttingen, 37073 Göttingen, Germany,Corresponding author
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11
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van Leeuwen W, Nguyen DTM, Grond R, Veenendaal T, Rabouille C, Farías GG. Stress-induced phase separation of ERES components into Sec bodies precedes ER exit inhibition in mammalian cells. J Cell Sci 2022; 135:jcs260294. [PMID: 36325988 PMCID: PMC10112967 DOI: 10.1242/jcs.260294] [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: 05/30/2022] [Accepted: 10/27/2022] [Indexed: 11/06/2022] Open
Abstract
Phase separation of components of ER exit sites (ERES) into membraneless compartments, the Sec bodies, occurs in Drosophila cells upon exposure to specific cellular stressors, namely, salt stress and amino acid starvation, and their formation is linked to the early secretory pathway inhibition. Here, we show Sec bodies also form in secretory mammalian cells upon the same stress. These reversible and membraneless structures are positive for ERES components, including both Sec16A and Sec16B isoforms and COPII subunits. We find that Sec16A, but not Sec16B, is a driver for Sec body formation, and that the coalescence of ERES components into Sec bodies occurs by fusion. Finally, we show that the stress-induced coalescence of ERES components into Sec bodies precedes ER exit inhibition, leading to their progressive depletion from ERES that become non-functional. Stress relief causes an immediate dissolution of Sec bodies and the concomitant restoration of ER exit. We propose that the dynamic conversion between ERES and Sec body assembly, driven by Sec16A, regulates protein exit from the ER during stress and upon stress relief in mammalian cells, thus providing a conserved pro-survival mechanism in response to stress.
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Affiliation(s)
- Wessel van Leeuwen
- Hubrecht Institute of the KNAW & UMC Utrecht, Utrecht 3584 CT, The Netherlands
| | - Dan T. M. Nguyen
- Cell Biology, Neurobiology and Biophysics. Department of Biology, Faculty of Science, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Rianne Grond
- Hubrecht Institute of the KNAW & UMC Utrecht, Utrecht 3584 CT, The Netherlands
| | - Tineke Veenendaal
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht 3584 CX, The Netherlands
| | - Catherine Rabouille
- Hubrecht Institute of the KNAW & UMC Utrecht, Utrecht 3584 CT, The Netherlands
- Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht 3584 CX, The Netherlands
- Department of Biomedical Sciences in Cells and Systems, UMC Groningen, Groningen 9713 AV, The Netherlands
| | - Ginny G. Farías
- Cell Biology, Neurobiology and Biophysics. Department of Biology, Faculty of Science, Utrecht University, Utrecht 3584 CH, The Netherlands
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