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Filippini F, Galli T. UNVEILING DEFECTS OF SECRETION MECHANISMS IN PARKINSON'S DISEASE. J Biol Chem 2024:107603. [PMID: 39059489 DOI: 10.1016/j.jbc.2024.107603] [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: 01/30/2024] [Revised: 07/11/2024] [Accepted: 07/15/2024] [Indexed: 07/28/2024] Open
Abstract
Neurodegenerative diseases are characterized by progressive dysfunction and loss of specific sets of neurons. While extensive research has focused on elucidating the genetic and epigenetic factors and molecular mechanisms underlying these disorders, emerging evidence highlights the critical role of secretion in the pathogenesis, possibly even onset, and progression of neurodegenerative diseases, suggesting the occurrence of non-cell-autonomous mechanisms. Secretion is a fundamental process that regulates intercellular communication, supports cellular homeostasis, and orchestrates various physiological functions in the body. Defective secretion can impair the release of neurotransmitters and other signaling molecules, disrupting synaptic transmission and compromising neuronal survival. It can also contribute to the accumulation, misfolding, and aggregation of disease-associated proteins, leading to neurotoxicity and neuronal dysfunction. In this review, we discuss the implications of defective secretion in the context of Parkinson's disease, emphasizing its role in protein aggregation, synaptic dysfunction, extracellular vesicle secretion and neuroinflammation. We propose a multiple-hit model whereby protein accumulation and secretory defects must be combined for the onset and progression of the disease.
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Affiliation(s)
- Francesca Filippini
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510; Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510
| | - Thierry Galli
- Université Paris Cité, Institute of Psychiatry and Neuroscience of Paris, INSERM U1266, Membrane Traffic in Healthy & Diseased Brain, 75014 Paris, France; GHU Paris Psychiatrie & Neurosciences, Paris, France.
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2
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Johnson DH, Kou OH, Bouzos N, Zeno WF. Protein-membrane interactions: sensing and generating curvature. Trends Biochem Sci 2024; 49:401-416. [PMID: 38508884 PMCID: PMC11069444 DOI: 10.1016/j.tibs.2024.02.005] [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: 09/23/2023] [Revised: 02/20/2024] [Accepted: 02/23/2024] [Indexed: 03/22/2024]
Abstract
Biological membranes are integral cellular structures that can be curved into various geometries. These curved structures are abundant in cells as they are essential for various physiological processes. However, curved membranes are inherently unstable, especially on nanometer length scales. To stabilize curved membranes, cells can utilize proteins that sense and generate membrane curvature. In this review, we summarize recent research that has advanced our understanding of interactions between proteins and curved membrane surfaces, as well as work that has expanded our ability to study curvature sensing and generation. Additionally, we look at specific examples of cellular processes that require membrane curvature, such as neurotransmission, clathrin-mediated endocytosis (CME), and organelle biogenesis.
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Affiliation(s)
- David H Johnson
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089, USA
| | - Orianna H Kou
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA
| | - Nicoletta Bouzos
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089, USA
| | - Wade F Zeno
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089, USA.
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3
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Di Bartolo AL, Caparotta M, Polo LM, Masone D. Myomerger Induces Membrane Hemifusion and Regulates Fusion Pore Expansion. Biochemistry 2024; 63:815-826. [PMID: 38349279 DOI: 10.1021/acs.biochem.3c00682] [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: 03/20/2024]
Abstract
Membrane fusion is a crucial mechanism in a wide variety of important events in cell biology from viral infection to exocytosis. However, despite many efforts and much progress, cell-cell fusion has remained elusive to our understanding. Along the life of the fusion pore, large conformational changes take place from the initial lipid bilayer bending, passing through the hemifusion intermediates, and ending with the formation of the first nascent fusion pore. In this sense, computer simulations are an ideal technique for describing such complex lipid remodeling at the molecular level. In this work, we studied the role played by the muscle-specific membrane protein Myomerger during the formation of the fusion pore. We have conducted μs length atomistic and coarse-grained molecular dynamics, together with free-energy calculations using ad hoc collective variables. Our results show that Myomerger favors the hemifusion diaphragm-stalk transition, reduces the nucleation-expansion energy difference, and promotes the formation of nonenlarging fusion pores.
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Affiliation(s)
- Ary Lautaro Di Bartolo
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo (UNCuyo), 5500 Mendoza, Argentina
| | - Marcelo Caparotta
- Quantum Theory Project, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Luis Mariano Polo
- Instituto de Histología y Embriología de Mendoza (IHEM)─Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo, 5500 Mendoza, Argentina
| | - Diego Masone
- Instituto de Histología y Embriología de Mendoza (IHEM)─Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo, 5500 Mendoza, Argentina
- Facultad de Ingeniería, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina
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4
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Runwal GM, Edwards RH. The role of α-synuclein in exocytosis. Exp Neurol 2024; 373:114668. [PMID: 38147972 DOI: 10.1016/j.expneurol.2023.114668] [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: 08/24/2023] [Revised: 11/28/2023] [Accepted: 12/19/2023] [Indexed: 12/28/2023]
Abstract
The pathogenesis of degeneration in Parkinson's disease (PD) remains poorly understood but multiple lines of evidence have converged on the presynaptic protein α-synuclein (αsyn). αSyn has been shown to regulate several cellular processes, however, its normal function remains poorly understood. In this review, we will specifically focus on its role in exocytosis.
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Affiliation(s)
- Gautam M Runwal
- Departments of Neurology and Physiology, UCSF School of Medicine, United States of America; Departments of Neurology and Physiology, UCSF School of Medicine, United States of America- Aligning Science Across Parkinson's Collaborative Research Network, Chevy Chase, MD 20815, United States of America
| | - Robert H Edwards
- Departments of Neurology and Physiology, UCSF School of Medicine, United States of America; Departments of Neurology and Physiology, UCSF School of Medicine, United States of America- Aligning Science Across Parkinson's Collaborative Research Network, Chevy Chase, MD 20815, United States of America.
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5
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Nordengen K, Morland C. From Synaptic Physiology to Synaptic Pathology: The Enigma of α-Synuclein. Int J Mol Sci 2024; 25:986. [PMID: 38256059 PMCID: PMC10815905 DOI: 10.3390/ijms25020986] [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: 11/30/2023] [Revised: 01/06/2024] [Accepted: 01/09/2024] [Indexed: 01/24/2024] Open
Abstract
Alpha-synuclein (α-syn) has gained significant attention due to its involvement in neurodegenerative diseases, particularly Parkinson's disease. However, its normal function in the human brain is equally fascinating. The α-syn protein is highly dynamic and can adapt to various conformational stages, which differ in their interaction with synaptic elements, their propensity to drive pathological aggregation, and their toxicity. This review will delve into the multifaceted role of α-syn in different types of synapses, shedding light on contributions to neurotransmission and overall brain function. We describe the physiological role of α-syn at central synapses, including the bidirectional interaction between α-syn and neurotransmitter systems.
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Affiliation(s)
- Kaja Nordengen
- Department of Neurology, Oslo University Hospital, 0424 Oslo, Norway
| | - Cecilie Morland
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, The Faculty of Mathematics and Natural Sciences, University of Oslo, 1068 Oslo, Norway
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6
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Smith AN, Joshi S, Chanzu H, Alfar HR, Prakhya KS, Whiteheart SW. α-Synuclein is the major platelet isoform but is dispensable for activation, secretion, and thrombosis. Platelets 2023; 34:2267147. [PMID: 37927048 PMCID: PMC10629845 DOI: 10.1080/09537104.2023.2267147] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 10/01/2023] [Indexed: 11/07/2023]
Abstract
Platelets play many roles in the vasculature ensuring proper hemostasis and maintaining integrity. These roles are facilitated, in part, by cargo molecules released from platelet granules via Soluble NSF Attachment Protein Receptor (SNARE) mediated membrane fusion, which is controlled by several protein-protein interactions. Chaperones have been characterized for t-SNAREs (i.e. Munc18b for Syntaxin-11), but none have been clearly identified for v-SNAREs. α-Synuclein has been proposed as a v-SNARE chaperone which may affect SNARE-complex assembly, fusion pore opening, and thus secretion. Despite its abundance and that it is the only isoform present, α-synuclein's role in platelet secretion is uncharacterized. In this study, immunofluorescence showed that α-synuclein was present on punctate structures that co-stained with markers for α-granules and lysosomes and in a cytoplasmic pool. We analyzed the phenotype of α-synuclein-/- mice and their platelets. Platelets from knockout mice had a mild, agonist-dependent secretion defect but aggregation and spreading in vitro were unaffected. Consistently, thrombosis/hemostasis were unaffected in the tail-bleeding, FeCl3 carotid injury and jugular vein puncture models. None of the platelet secretory machinery examined, e.g. the v-SNAREs, were affected by α-synuclein's loss. The results indicate that, despite its abundance, α-synuclein has only a limited role in platelet function and thrombosis.
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Affiliation(s)
- Alexis N. Smith
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY, USA
| | - Smita Joshi
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY, USA
| | - Harry Chanzu
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY, USA
- Present address: GenScript USA Inc., 860 Centennial Ave. Piscataway, NJ 08854, USA
| | - Hammodah R. Alfar
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY, USA
| | | | - Sidney W. Whiteheart
- Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY, USA
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7
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Ju JQ, Fissore RA, Sun SC. Editorial: Editors' showcase 2022: insights in molecular and cellular reproduction. Front Cell Dev Biol 2023; 11:1321358. [PMID: 38020921 PMCID: PMC10679668 DOI: 10.3389/fcell.2023.1321358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 11/03/2023] [Indexed: 12/01/2023] Open
Affiliation(s)
- Jia-Qian Ju
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Rafael A. Fissore
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, MA, United States
| | - Shao-Chen Sun
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
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8
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Buzzatto MV, Berberián MV, Di Bartolo AL, Masone D, Tomes CN. α-Synuclein is required for sperm exocytosis at a post-fusion stage. Front Cell Dev Biol 2023; 11:1125988. [PMID: 37287458 PMCID: PMC10242118 DOI: 10.3389/fcell.2023.1125988] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 05/09/2023] [Indexed: 06/09/2023] Open
Abstract
The sperm acrosome is a large dense-core granule whose contents are secreted by regulated exocytosis at fertilization through the opening of numerous fusion pores between the acrosomal and plasma membranes. In other cells, the nascent pore generated when the membrane surrounding a secretory vesicle fuses with the plasma membrane may have different fates. In sperm, pore dilation leads to the vesiculation and release of these membranes, together with the granule contents. α-Synuclein is a small cytosolic protein claimed to exhibit different roles in exocytic pathways in neurons and neuroendocrine cells. Here, we scrutinized its function in human sperm. Western blot revealed the presence of α-synuclein and indirect immunofluorescence its localization to the acrosomal domain of human sperm. Despite its small size, the protein was retained following permeabilization of the plasma membrane with streptolysin O. α-Synuclein was required for acrosomal release, as demonstrated by the inability of an inducer to elicit exocytosis when permeabilized human sperm were loaded with inhibitory antibodies to human α-synuclein. The antibodies halted calcium-induced secretion when introduced after the acrosome docked to the cell membrane. Two functional assays, fluorescence and transmission electron microscopies revealed that the stabilization of open fusion pores was responsible for the secretion blockage. Interestingly, synaptobrevin was insensitive to neurotoxin cleavage at this point, an indication of its engagement in cis SNARE complexes. The very existence of such complexes during AE reflects a new paradigm. Recombinant α-synuclein rescued the inhibitory effects of the anti-α-synuclein antibodies and of a chimeric Rab3A-22A protein that also inhibits AE after fusion pore opening. We applied restrained molecular dynamics simulations to compare the energy cost of expanding a nascent fusion pore between two model membranes and found it higher in the absence than in the presence of α-synuclein. Hence, our results suggest that α-synuclein is essential for expanding fusion pores.
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Affiliation(s)
- Micaela Vanina Buzzatto
- Instituto de Histología y Embriología de Mendoza (IHEM)-CONICET-Universidad Nacional de Cuyo, Mendoza, Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - María Victoria Berberián
- Instituto de Histología y Embriología de Mendoza (IHEM)-CONICET-Universidad Nacional de Cuyo, Mendoza, Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina
- Instituto de Ciencias Básicas (ICB)-CONICET-Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Ary Lautaro Di Bartolo
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Diego Masone
- Instituto de Histología y Embriología de Mendoza (IHEM)-CONICET-Universidad Nacional de Cuyo, Mendoza, Argentina
- Facultad de Ingeniería, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Claudia Nora Tomes
- Instituto de Histología y Embriología de Mendoza (IHEM)-CONICET-Universidad Nacional de Cuyo, Mendoza, Argentina
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina
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9
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Di Bartolo AL, Caparotta M, Masone D. Intrinsic Disorder in α-Synuclein Regulates the Exocytotic Fusion Pore Transition. ACS Chem Neurosci 2023. [PMID: 37192400 DOI: 10.1021/acschemneuro.3c00040] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2023] Open
Abstract
Today, it is widely accepted that intrinsic disorder is strongly related to the cell cycle, during mitosis, differentiation, and apoptosis. Of particular interest are hybrid proteins possessing both structured and unstructured domains that are critical in human health and disease, such as α-synuclein. In this work, we describe how α-synuclein interacts with the nascent fusion pore as it evolves toward expansion. We unveil the key role played by its intrinsically disordered region as a thermodynamic regulator of the nucleation-expansion energy barrier. By analyzing a truncated variant of α-synuclein that lacks the disordered region, we find that the landscape of protein interactions with PIP2 and POPS lipids is highly altered, ultimately increasing the energy cost for the fusion pore to transit from nucleation to expansion. We conclude that the intrinsically disordered region in full-length α-synuclein recognizes and allocates pivotal protein:lipid interactions during membrane remodeling in the first stages of the fusion pore.
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Affiliation(s)
- Ary Lautaro Di Bartolo
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo (UNCuyo), 5500 Mendoza, Argentina
| | - Marcelo Caparotta
- Quantum Theory Project, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Diego Masone
- Instituto de Histología y Embriología de Mendoza (IHEM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo (UNCuyo), 5500 Mendoza, Argentina
- Facultad de Ingeniería, Universidad Nacional de Cuyo (UNCuyo), 5500 Mendoza, Argentina
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10
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Yang Z, Yao Y, Zhou Y, Li X, Tang Y, Wei G. EGCG attenuates α-synuclein protofibril-membrane interactions and disrupts the protofibril. Int J Biol Macromol 2023; 230:123194. [PMID: 36623616 DOI: 10.1016/j.ijbiomac.2023.123194] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Revised: 12/15/2022] [Accepted: 01/04/2023] [Indexed: 01/09/2023]
Abstract
The fibrillary aggregates of α-synuclein (α-syn) are closely associated with the etiology of Parkinson's disease (PD). Mounting evidence shows that the interaction of α-syn with biological membranes is a culprit for its aggregation and cytotoxicity. While some small molecules can effectively inhibit α-syn fibrillization in solution, their potential roles in the presence of membrane are rarely studied. Among them, green tea extract epigallocatechin gallate (EGCG) is currently under active investigation. Herein, we investigated the effects of EGCG on α-syn protofibril (an intermediate of α-syn fibril formation) in the presence of a model membrane and on the interactions between α-syn protofibril and the membrane, as well as the underlying mechanisms, by performing microsecond all-atom molecular dynamics simulations. The results show that EGCG has destabilization effects on α-syn protofibril, albeit to a lesser extent than that in solution. Intriguingly, we find that EGCG forms overwhelming H-bonding and cation-π interactions with membrane and thus attenuates protofibril-membrane interactions. Moreover, the decreased protofibril-membrane interactions impede the membrane damage by α-syn protofibril and enable the membrane integrity. These findings provide atomistic understanding towards the attenuation of α-syn protofibril-induced cytotoxicity by EGCG in cellular environment, which is helpful for the development of EGCG-based therapeutic strategies against PD.
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Affiliation(s)
- Zhongyuan Yang
- State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Department of Physics, Fudan University, Shanghai 200438, People's Republic of China
| | - Yifei Yao
- State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Department of Physics, Fudan University, Shanghai 200438, People's Republic of China
| | - Yun Zhou
- State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Department of Physics, Fudan University, Shanghai 200438, People's Republic of China
| | - Xuhua Li
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China
| | - Yiming Tang
- State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Department of Physics, Fudan University, Shanghai 200438, People's Republic of China.
| | - Guanghong Wei
- State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Department of Physics, Fudan University, Shanghai 200438, People's Republic of China.
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11
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Sharma M, Burré J. α-Synuclein in synaptic function and dysfunction. Trends Neurosci 2023; 46:153-166. [PMID: 36567199 PMCID: PMC9877183 DOI: 10.1016/j.tins.2022.11.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 11/07/2022] [Accepted: 11/29/2022] [Indexed: 12/24/2022]
Abstract
α-Synuclein is a neuronal protein that is enriched in presynaptic terminals. Under physiological conditions, it binds to synaptic vesicle membranes and functions in neurotransmitter release, although the molecular details remain unclear, and it is controversial whether α-synuclein inhibits or facilitates neurotransmitter release. Pathologically, in synucleinopathies including Parkinson's disease (PD), α-synuclein forms aggregates that recruit monomeric α-synuclein and spread throughout the brain, which triggers neuronal dysfunction at molecular, cellular, and organ levels. Here, we present an overview of the effects of α-synuclein on SNARE-complex assembly, neurotransmitter release, and synaptic vesicle pool homeostasis, and discuss how the observed divergent effects of α-synuclein on neurotransmitter release can be reconciled. We also discuss how gain-of-function versus loss-of-function of α-synuclein may contribute to pathogenesis in synucleinopathies.
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Affiliation(s)
- Manu Sharma
- Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA.
| | - Jacqueline Burré
- Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA.
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12
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The Role of α-Synuclein in SNARE-mediated Synaptic Vesicle Fusion. J Mol Biol 2023; 435:167775. [PMID: 35931109 DOI: 10.1016/j.jmb.2022.167775] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 07/28/2022] [Accepted: 07/28/2022] [Indexed: 02/04/2023]
Abstract
Neuronal communication depends on exquisitely regulated membrane fusion between synaptic vesicles and presynaptic neurons, which results in neurotransmitter release in precisely timed patterns. Presynaptic dysfunctions are known to occur prior to the onset of neurodegenerative diseases, including Parkinson's disease. Synaptic accumulation of α-synuclein (α-Syn) oligomers has been implicated in the pathway leading to such outcomes. α-Syn oligomers exert aberrant effects on presynaptic fusion machinery through their interactions with synaptic vesicles and proteins. Here, we summarize in vitro bulk and single-vesicle assays for investigating the functions of α-Syn monomers and oligomers in synaptic vesicle fusion and then discuss the current understanding of the roles of α-Syn monomers and oligomers in synaptic vesicle fusion. Finally, we suggest a new therapeutic avenue specifically targeting the mechanisms of α-Syn oligomer toxicity rather than the oligomer itself.
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13
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Di Bartolo AL, Tomes CN, Mayorga LS, Masone D. Enhanced Expansion and Reduced Kiss-and-Run Events in Fusion Pores Steered by Synaptotagmin-1 C2B Domains. J Chem Theory Comput 2022; 18:4544-4554. [PMID: 35759758 DOI: 10.1021/acs.jctc.2c00424] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The fusion pore controls the release of exocytotic vesicle contents through a precise orchestration of lipids from the fusing membranes and proteins. There is a major lipid reorganization during the different stages in life of the fusion pore (membrane fusion, nucleation, and expansion) that can be scrutinized thermodynamically. In this work, using umbrella sampling simulations we describe the expansion of the fusion pore. We have calculated free energy profiles to drive a nascent, just nucleated, fusion pore to its expanded configuration. We have quantified the effects on the free energy of one and two Synaptotagmin-1 C2B domains in the cytosolic space. We show that C2B domains cumulatively reduce the cost for expansion, favoring the system to evolve toward full fusion. Finally, by conducting thousands of unbiased molecular dynamics simulations, we show that C2B domains significantly decrease the probability of kiss-and-run events.
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Affiliation(s)
- Ary Lautaro Di Bartolo
- Instituto de Histología y Embriología de Mendoza (IHEM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo (UNCuyo), 5500 Mendoza, Argentina.,Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo (UNCuyo), 5500 Mendoza, Argentina
| | - Claudia N Tomes
- Instituto de Histología y Embriología de Mendoza (IHEM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo (UNCuyo), 5500 Mendoza, Argentina.,Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo (UNCuyo), 5500 Mendoza, Argentina
| | - Luis S Mayorga
- Instituto de Histología y Embriología de Mendoza (IHEM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo (UNCuyo), 5500 Mendoza, Argentina.,Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo (UNCuyo), 5500 Mendoza, Argentina
| | - Diego Masone
- Instituto de Histología y Embriología de Mendoza (IHEM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo (UNCuyo), 5500 Mendoza, Argentina.,Facultad de Ingeniería, Universidad Nacional de Cuyo (UNCuyo), 5500 Mendoza, Argentina
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14
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Bonaccorsi di Patti MC, Angiulli E, Casini A, Vaccaro R, Cioni C, Toni M. Synuclein Analysis in Adult Xenopus laevis. Int J Mol Sci 2022; 23:ijms23116058. [PMID: 35682736 PMCID: PMC9181771 DOI: 10.3390/ijms23116058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 05/23/2022] [Accepted: 05/26/2022] [Indexed: 11/16/2022] Open
Abstract
The α-, β- and γ-synucleins are small soluble proteins expressed in the nervous system of mammals and evolutionary conserved in vertebrates. After being discovered in the cartilaginous fish Torpedo californica, synucleins have been sequenced in all vertebrates, showing differences in the number of genes and splicing isoforms in different taxa. Although α-, β- and γ-synucleins share high homology in the N-terminal sequence, suggesting their evolution from a common ancestor, the three isoforms also differ in molecular characteristics, expression levels and tissue distribution. Moreover, their functions have yet to be fully understood. Great scientific interest on synucleins mainly derives from the involvement of α-synuclein in human neurodegenerative diseases, collectively named synucleinopathies, which involve the accumulation of amyloidogenic α-synuclein inclusions in neurons and glia cells. Studies on synucleinopathies can take advantage of the development of new vertebrate models other than mammals. Moreover, synuclein expression in non-mammalian vertebrates contribute to clarify the physiological role of these proteins in the evolutionary perspective. In this paper, gene expression levels of α-, β- and γ-synucleins have been analysed in the main organs of adult Xenopus laevis by qRT-PCR. Moreover, recombinant α-, β- and γ-synucleins were produced to test the specificity of commercial antibodies against α-synuclein used in Western blot and immunohistochemistry. Finally, the secondary structure of Xenopus synucleins was evaluated by circular dichroism analysis. Results indicate Xenopus as a good model for studying synucleinopathies, and provide a useful background for future studies on synuclein functions and their evolution in vertebrates.
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Affiliation(s)
| | - Elisa Angiulli
- Department of Biology and Biotechnology “Charles Darwin”, Sapienza University, 00161 Rome, Italy; (E.A.); (C.C.)
| | - Arianna Casini
- Department of Anatomical, Histological, Forensic Medicine and Orthopedic Sciences, Sapienza University, 00161 Rome, Italy; (A.C.); (R.V.)
| | - Rosa Vaccaro
- Department of Anatomical, Histological, Forensic Medicine and Orthopedic Sciences, Sapienza University, 00161 Rome, Italy; (A.C.); (R.V.)
| | - Carla Cioni
- Department of Biology and Biotechnology “Charles Darwin”, Sapienza University, 00161 Rome, Italy; (E.A.); (C.C.)
| | - Mattia Toni
- Department of Biology and Biotechnology “Charles Darwin”, Sapienza University, 00161 Rome, Italy; (E.A.); (C.C.)
- Correspondence: (M.C.B.d.P.); (M.T.)
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15
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α-Synuclein at the Presynaptic Axon Terminal as a Double-Edged Sword. Biomolecules 2022; 12:biom12040507. [PMID: 35454096 PMCID: PMC9029495 DOI: 10.3390/biom12040507] [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: 02/23/2022] [Revised: 03/22/2022] [Accepted: 03/23/2022] [Indexed: 12/12/2022] Open
Abstract
α-synuclein (α-syn) is a presynaptic, lipid-binding protein strongly associated with the neuropathology observed in Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and Alzheimer’s Disease (AD). In normal physiology, α-syn plays a pivotal role in facilitating endocytosis and exocytosis. Interestingly, mutations and modifications of precise α-syn domains interfere with α-syn oligomerization and nucleation that negatively affect presynaptic vesicular dynamics, protein expressions, and mitochondrial profiles. Furthermore, the integration of the α-syn oligomers into the presynaptic membrane results in pore formations, ion influx, and excitotoxicity. Targeted therapies against specific domains of α-syn, including the use of small organic molecules, monoclonal antibodies, and synthetic peptides, are being screened and developed. However, the prospect of an effective α-syn targeted therapy is still plagued by low permeability across the blood–brain barrier (BBB), and poor entry into the presynaptic axon terminals. The present review proposes a modification of current strategies, which includes the use of novel encapsulation technology, such as lipid nanoparticles, to bypass the BBB and deliver such agents into the brain.
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16
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Pierson J, Shin YK. Stabilization of the SNARE Core by Complexin-1 Facilitates Fusion Pore Expansion. Front Mol Biosci 2022; 8:805000. [PMID: 34970598 PMCID: PMC8712692 DOI: 10.3389/fmolb.2021.805000] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 11/26/2021] [Indexed: 11/13/2022] Open
Abstract
In the neuron, neurotransmitter release is an essential function that must be both consistent and tightly regulated. The continuity of neurotransmitter release is dependent in large part on vesicle recycling. However, the protein factors that dictate the vesicle recycling pathway are elusive. Here, we use a single vesicle-to-supported bilayer fusion assay to investigate complexin-1 (cpx1)’s influence on SNARE-dependent fusion pore expansion. With total internal reflection (TIR) microscopy using a 10 kDa polymer fluorescence probe, we are able to detect the presence of large fusion pores. With cpx1, however, we observe a significant increase of the probability of the formation of large fusion pores. The domain deletion analysis reveals that the SNARE-binding core domain of cpx1 is mainly responsible for its ability to promote the fusion pore expansion. In addition, the results show that cpx1 helps the pore to expand larger, which results in faster release of the polymer probe. Thus, the results demonstrate a reciprocal relationship between event duration and the size of the fusion pore. Based on the data, a hypothetical mechanistic model can be deduced. In this mechanistic model, the cpx1 binding stabilizes the four-helix bundle structure of the SNARE core throughout the fusion pore expansion, whereby the highly curved bilayer within the fusion pore is stabilized by the SNARE pins.
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Affiliation(s)
- Josh Pierson
- Professor Yeon-Kyun Shin Lab, Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, United States
| | - Yeon-Kyun Shin
- Professor Yeon-Kyun Shin Lab, Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA, United States
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