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Stephens AD, Villegas AF, Chung CW, Vanderpoorten O, Pinotsi D, Mela I, Ward E, McCoy TM, Cubitt R, Routh AF, Kaminski CF, Kaminski Schierle GS. α-Synuclein fibril and synaptic vesicle interactions lead to vesicle destruction and increased lipid-associated fibril uptake into iPSC-derived neurons. Commun Biol 2023; 6:526. [PMID: 37188797 PMCID: PMC10185682 DOI: 10.1038/s42003-023-04884-1] [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: 11/26/2022] [Accepted: 04/27/2023] [Indexed: 05/17/2023] Open
Abstract
Monomeric alpha-synuclein (aSyn) is a well characterised protein that importantly binds to lipids. aSyn monomers assemble into amyloid fibrils which are localised to lipids and organelles in insoluble structures found in Parkinson's disease patient's brains. Previous work to address pathological aSyn-lipid interactions has focused on using synthetic lipid membranes, which lack the complexity of physiological lipid membranes. Here, we use physiological membranes in the form of synaptic vesicles (SV) isolated from rodent brain to demonstrate that lipid-associated aSyn fibrils are more easily taken up into iPSC-derived cortical i3Neurons. Lipid-associated aSyn fibril characterisation reveals that SV lipids are an integrated part of the fibrils and while their fibril morphology differs from aSyn fibrils alone, the core fibril structure remains the same, suggesting the lipids lead to the increase in fibril uptake. Furthermore, SV enhance the aggregation rate of aSyn, yet increasing the SV:aSyn ratio causes a reduction in aggregation propensity. We finally show that aSyn fibrils disintegrate SV, whereas aSyn monomers cause clustering of SV using small angle neutron scattering and high-resolution imaging. Disease burden on neurons may be impacted by an increased uptake of lipid-associated aSyn which could enhance stress and pathology, which in turn may have fatal consequences for neurons.
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Affiliation(s)
- Amberley D Stephens
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK.
| | - Ana Fernandez Villegas
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Chyi Wei Chung
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
- Department of Physics, Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK
| | - Oliver Vanderpoorten
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
- Department of Physics and Technology, UiT The Arctic University of Norway, Tromsø, Norway
| | - Dorothea Pinotsi
- Scientific Center for Optical and Electron Microscopy, ETH Zürich, Zürich, Switzerland
| | - Ioanna Mela
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Edward Ward
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Thomas M McCoy
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | | | - Alexander F Routh
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
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Montalbo RCK, Tu HL. Micropatterning of functional lipid bilayer assays for quantitative bioanalysis. BIOMICROFLUIDICS 2023; 17:031302. [PMID: 37179590 PMCID: PMC10171888 DOI: 10.1063/5.0145997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 04/24/2023] [Indexed: 05/15/2023]
Abstract
Interactions of the cell with its environment are mediated by the cell membrane and membrane-localized molecules. Supported lipid bilayers have enabled the recapitulation of the basic properties of cell membranes and have been broadly used to further our understanding of cellular behavior. Coupled with micropatterning techniques, lipid bilayer platforms have allowed for high throughput assays capable of performing quantitative analysis at a high spatiotemporal resolution. Here, an overview of the current methods of the lipid membrane patterning is presented. The fabrication and pattern characteristics are briefly described to present an idea of the quality and notable features of the methods, their utilizations for quantitative bioanalysis, as well as to highlight possible directions for the advanced micropatterning lipid membrane assays.
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Heo P, Culver JA, Miao J, Pincet F, Mariappan M. The Get1/2 insertase forms a channel to mediate the insertion of tail-anchored proteins into the ER. Cell Rep 2023; 42:111921. [PMID: 36640319 PMCID: PMC9932932 DOI: 10.1016/j.celrep.2022.111921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 11/07/2022] [Accepted: 12/13/2022] [Indexed: 12/29/2022] Open
Abstract
Tail-anchored (TA) proteins contain a single C-terminal transmembrane domain (TMD) that is captured by the cytosolic Get3 in yeast (TRC40 in humans). Get3 delivers TA proteins to the Get1/2 complex for insertion into the endoplasmic reticulum (ER) membrane. How Get1/2 mediates insertion of TMDs of TA proteins into the membrane is poorly understood. Using bulk fluorescence and microfluidics assays, we show that Get1/2 forms an aqueous channel in reconstituted bilayers. We estimate the channel diameter to be ∼2.5 nm wide, corresponding to the circumference of two Get1/2 complexes. We find that the Get3 binding can seal the Get1/2 channel, which dynamically opens and closes. Our mutation analysis further shows that the Get1/2 channel activity is required to release TA proteins from Get3 for insertion into the membrane. Hence, we propose that the Get1/2 channel functions as an insertase for insertion of TMDs and as a translocase for translocation of C-terminal hydrophilic segments.
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Affiliation(s)
- Paul Heo
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France; Institute of Psychiatry and Neuroscience of Paris, INSERM U1266, 75014 Paris, France.
| | - Jacob A. Culver
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA,Nanobiology Institute, Yale University West Campus, West Haven, CT 06516, USA
| | - Jennifer Miao
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA,Nanobiology Institute, Yale University West Campus, West Haven, CT 06516, USA
| | - Frederic Pincet
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France.
| | - Malaiyalam Mariappan
- Department of Cell Biology, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Nanobiology Institute, Yale University West Campus, West Haven, CT 06516, USA.
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Yoo G, An HJ, Yeou S, Lee NK. α-Synuclein Disrupts Vesicle Fusion by Two Mutant-Specific Mechanisms. Mol Cells 2022; 45:806-819. [PMID: 36380732 PMCID: PMC9676983 DOI: 10.14348/molcells.2022.0102] [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: 06/23/2022] [Revised: 07/26/2022] [Accepted: 07/28/2022] [Indexed: 11/17/2022] Open
Abstract
Synaptic accumulation of α-synuclein (α-Syn) oligomers and their interactions with VAMP2 have been reported to be the basis of synaptic dysfunction in Parkinson's disease (PD). α-Syn mutants associated with familial PD have also been known to be capable of interacting with VAMP2, but the exact mechanisms resulting from those interactions to eventual synaptic dysfunction are still unclear. Here, we investigate the effect of α-Syn mutant oligomers comprising A30P, E46K, and A53T on VAMP2-embedded vesicles. Specifically, A30P and A53T oligomers cluster vesicles in the presence of VAMP2, which is a shared mechanism with wild type α-Syn oligomers induced by dopamine. On the other hand, E46K oligomers reduce the membrane mobility of the planar bilayers, as revealed by single-particle tracking, and permeabilize the membranes in the presence of VAMP2. In the absence of VAMP2 interactions, E46K oligomers enlarge vesicles by fusing with one another. Our results clearly demonstrate that α-Syn mutant oligomers have aberrant effects on VAMP2-embedded vesicles and the disruption types are distinct depending on the mutant types. This work may provide one of the possible clues to explain the α-Syn mutant-type dependent pathological heterogeneity of familial PD.
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Affiliation(s)
- Gyeongji Yoo
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Hyeong Jeon An
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Sanghun Yeou
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Nam Ki Lee
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
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Durell SR, Guy HR. The amyloid concentric β-barrel hypothesis: Models of synuclein oligomers, annular protofibrils, lipoproteins, and transmembrane channels. Proteins 2022; 90:512-542. [PMID: 34570382 PMCID: PMC8988847 DOI: 10.1002/prot.26249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 09/13/2021] [Indexed: 02/03/2023]
Abstract
Amyloid beta (Aβ of Alzheimer's disease) and α-synuclein (α-Syn of Parkinson's disease) form large fibrils. Evidence is increasing however that much smaller oligomers are more toxic and that these oligomers can form transmembrane ion channels. We have proposed previously that Aβ42 oligomers, annular protofibrils, and ion channels adopt concentric β-barrel molecular structures. Here we extend that hypothesis to the superfamily of α, β, and γ-synucleins. Our models of numerous synuclein oligomers, annular protofibrils, tubular protofibrils, lipoproteins, and ion channels were developed to be consistent with sizes, shapes, molecular weights, and secondary structures of assemblies as determined by electron microscopy and other studies. The models have the following features: (1) all subunits have identical structures and interactions; (2) they are consistent with conventional β-barrel theory; (3) the distance between walls of adjacent β-barrels is between 0.6 and 1.2 nm; (4) hydrogen bonds, salt bridges, interactions among aromatic side-chains, burial and tight packing of hydrophobic side-chains, and aqueous solvent exposure of hydrophilic side-chains are relatively optimal; and (5) residues that are identical among distantly related homologous proteins cluster in the interior of most oligomers whereas residues that are hypervariable are exposed on protein surfaces. Atomic scale models of some assemblies were developed.
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Affiliation(s)
- Stewart R Durell
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - H Robert Guy
- Amyloid Research Consultants (ARC), Cochiti Lake, New Mexico, USA
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Abstract
Using our recently designed microfluidic setup, we investigated the early stage of SNAREpin-induced fusion. We discovered the existence of subsecond transient fusion pores with a well-defined subnanometer size that occur when one or two SNAREpins are mediating vesicle fusion. In contrast, when vesicle fusion is mediated by three SNAREpins, the fusion pore reaches a diameter larger than 1.5 nm and expands spontaneously and indefinitely. These results quantitatively explain the need for a complex machinery to ensure a submillisecond neurotransmitter release after the arrival of the action potential during synaptic transmission. Vesicle fusion with a target membrane is a key event in cellular trafficking and ensures cargo transport within the cell and between cells. The formation of a protein complex, called SNAREpin, provides the energy necessary for the fusion process. In a three-dimensional microfluidic chip, we monitored the fusion of small vesicles with a suspended asymmetric lipid bilayer. Adding ion channels into the vesicles, our setup allows the observation of a single fusion event by electrophysiology with 10-μs precision. Intriguingly, we identified that small transient fusion pores of discrete sizes reversibly opened with a characteristic lifetime of ∼350 ms. The distribution of their apparent diameters displayed two peaks, at 0.4 ± 0.1 nm and 0.8 ± 0.2 nm. Varying the number of SNAREpins, we demonstrated that the first peak corresponds to fusion pores induced by a single SNAREpin and the second peak is associated with pores involving two SNAREpins acting simultaneously. The pore size fluctuations provide a direct estimate of the energy landscape of the pore. By extrapolation, the energy landscape for three SNAREpins does not exhibit any thermally significant energy barrier, showing that pores larger than 1.5 nm are spontaneously produced by three or more SNAREpins acting simultaneously, and expand indefinitely. Our results quantitatively explain why one SNAREpin is sufficient to open a fusion pore and more than three SNAREpins are required for cargo release. Finally, they also explain why a machinery that synchronizes three SNAREpins, or more, is mandatory to ensure fast neurotransmitter release during synaptic transmission.
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Musteikytė G, Jayaram AK, Xu CK, Vendruscolo M, Krainer G, Knowles TPJ. Interactions of α-synuclein oligomers with lipid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1863:183536. [PMID: 33373595 DOI: 10.1016/j.bbamem.2020.183536] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 12/10/2020] [Accepted: 12/13/2020] [Indexed: 12/24/2022]
Abstract
Parkinson's disease is an increasingly prevalent and currently incurable neurodegenerative disorder. At the molecular level, this disease is characterized by the formation of aberrant intracellular protein deposits known as Lewy bodies. Oligomeric forms of the protein α-synuclein (αS), which are believed to be both intermediates and by-products of Lewy body formation, are considered to be the main pathogenic species. Interactions of such oligomers with lipid membranes are increasingly emerging as a major molecular pathway underpinning their toxicity. Here we review recent progress in our understanding of the interactions of αS oligomers with lipid membranes. We highlight key structural and biophysical features of αS oligomers, the effects of these features on αS oligomer membrane binding properties, and resultant implications for understanding the etiology of Parkinson's disease. We discuss mechanistic modes of αS oligomer-lipid membrane interactions and the effects of environmental factors to such modes. Finally, we provide an overview of the current understanding of the main molecular determinants of αS oligomer toxicity in vivo.
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Affiliation(s)
- Greta Musteikytė
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Akhila K Jayaram
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom; Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Catherine K Xu
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Michele Vendruscolo
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Georg Krainer
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.
| | - Tuomas P J Knowles
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom; Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, United Kingdom.
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