1
|
Ibarra-Gutiérrez MT, Serrano-García N, Orozco-Ibarra M. Rotenone-Induced Model of Parkinson's Disease: Beyond Mitochondrial Complex I Inhibition. Mol Neurobiol 2023; 60:1929-1948. [PMID: 36593435 DOI: 10.1007/s12035-022-03193-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 12/23/2022] [Indexed: 01/04/2023]
Abstract
Parkinson's disease (PD) is usually diagnosed through motor symptoms that make the patient incapable of carrying out daily activities; however, numerous non-motor symptoms include olfactory disturbances, constipation, depression, excessive daytime sleepiness, and rapid eye movement at sleep; they begin years before motor symptoms. Therefore, several experimental models have been studied to reproduce several PD functional and neurochemical characteristics; however, no model mimics all the PD motor and non-motor symptoms to date, which becomes a limitation for PD study. It has become increasingly relevant to find ways to study the disease from its slowly progressive nature. The experimental models most frequently used to reproduce PD are based on administering toxic chemical compounds, which aim to imitate dopamine deficiency. The most used toxic compounds to model PD have been 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 6-hydroxydopamine (6-OHDA), which inhibit the complex I of the electron transport chain but have some limitations. Another toxic compound that has drawn attention recently is rotenone, the classical inhibitor of mitochondrial complex I. Rotenone triggers the progressive death of dopaminergic neurons and α-synuclein inclusions formation in rats; also, rotenone induces microtubule destabilization. This review presents information about the experimental model of PD induced by rotenone, emphasizing its molecular characteristics beyond the inhibition of mitochondrial complex I.
Collapse
Affiliation(s)
- María Teresa Ibarra-Gutiérrez
- Laboratorio de Neurobiología Molecular y Celular, Instituto Nacional de Neurología y Neurocirugía, Av. Insurgentes Sur No. 3877 Col. La Fama, Tlalpan, C.P. 14269, Ciudad de Mexico, Mexico
| | - Norma Serrano-García
- Laboratorio de Neurobiología Molecular y Celular, Instituto Nacional de Neurología y Neurocirugía, Av. Insurgentes Sur No. 3877 Col. La Fama, Tlalpan, C.P. 14269, Ciudad de Mexico, Mexico
| | - Marisol Orozco-Ibarra
- Laboratorio de Neurobiología Molecular y Celular, Instituto Nacional de Neurología y Neurocirugía, Av. Insurgentes Sur No. 3877 Col. La Fama, Tlalpan, C.P. 14269, Ciudad de Mexico, Mexico.
| |
Collapse
|
2
|
Dubackic M, Liu Y, Kelley EG, Hetherington C, Haertlein M, Devos JM, Linse S, Sparr E, Olsson U. α-Synuclein Interaction with Lipid Bilayer Discs. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:10216-10224. [PMID: 35952001 PMCID: PMC9404543 DOI: 10.1021/acs.langmuir.2c01368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/18/2022] [Indexed: 06/15/2023]
Abstract
α-Synuclein (aSyn) is a 140 residue long protein present in presynaptic termini of nerve cells. The protein is associated with Parkinson's disease, in which case it has been found to self-assemble into long amyloid fibrils forming intracellular inclusions that are also rich in lipids. Furthermore, its synaptic function is proposed to involve interaction with lipid membranes, and hence, it is of interest to understand aSyn-lipid membrane interactions in detail. In this paper we report on the interaction of aSyn with model membranes in the form of lipid bilayer discs. Using a combination of cryogenic transmission electron microscopy and small-angle neutron scattering, we show that circular discs undergo a significant shape transition after the adsorption of aSyn. When aSyn self-assembles into fibrils, aSyn molecules desorb from the bilayer discs, allowing them to recover to their original shape. Interestingly, the desorption process has an all-or-none character, resulting in a binary coexistence of circular bilayer discs with no adsorbed aSyn and deformed bilayer discs having a maximum amount of adsorbed protein. The observed coexistence is consistent with the recent finding of cooperative aSyn adsorption to anionic lipid bilayers.
Collapse
Affiliation(s)
- Marija Dubackic
- Physical
Chemistry, Department of Chemistry, Lund
University, SE-22100 Lund, Sweden
| | - Yun Liu
- Center
for Neutron Research, National Institute
of Standards and Technology, Gaithersburg, Maryland 20878, United States
- Chemical
and Biomolecular Engineering Department, University of Delaware, Newark, Delaware 19716, United States
| | - Elizabeth G. Kelley
- Center
for Neutron Research, National Institute
of Standards and Technology, Gaithersburg, Maryland 20878, United States
| | - Crispin Hetherington
- National
Center for High Resolution Electron Microscopy, Centre for Analysis
and Synthesis, Chemistry Centre, Lund University, SE-22100 Lund, Sweden
| | | | | | - Sara Linse
- Biochemistry
and Structural Biology, Department of Chemistry, Lund University, SE-22100 Lund, Sweden
| | - Emma Sparr
- Physical
Chemistry, Department of Chemistry, Lund
University, SE-22100 Lund, Sweden
| | - Ulf Olsson
- Physical
Chemistry, Department of Chemistry, Lund
University, SE-22100 Lund, Sweden
| |
Collapse
|
3
|
Multiomics implicate gut microbiota in altered lipid and energy metabolism in Parkinson's disease. NPJ Parkinsons Dis 2022; 8:39. [PMID: 35411052 PMCID: PMC9001728 DOI: 10.1038/s41531-022-00300-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 03/04/2022] [Indexed: 12/19/2022] Open
Abstract
We aimed to investigate the link between serum metabolites, gut bacterial community composition, and clinical variables in Parkinson’s disease (PD) and healthy control subjects (HC). A total of 124 subjects were part of the study (63 PD patients and 61 HC subjects). 139 metabolite features were found to be predictive between the PD and Control groups. No associations were found between metabolite features and within-PD clinical variables. The results suggest alterations in serum metabolite profiles in PD, and the results of correlation analysis between metabolite features and microbiota suggest that several bacterial taxa are associated with altered lipid and energy metabolism in PD.
Collapse
|
4
|
Jadavi S, Canepa E, Diaspro A, Canale C, Relini A, Dante S. α-Synuclein interacts differently with membranes mimicking the inner and outer leaflets of neuronal membranes. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183814. [PMID: 34774499 DOI: 10.1016/j.bbamem.2021.183814] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/26/2021] [Accepted: 10/27/2021] [Indexed: 12/29/2022]
Abstract
The toxicity of α-synuclein (α-syn), the amyloidogenic protein responsible for Parkinson's disease, is likely related to its interaction with the asymmetric neuronal membrane. α-Syn exists as cytoplasmatic and as extracellular protein as well. To shed light on the different interactions occurring at the different α-syn localizations, we have here modelled the external and internal membrane leaflets of the neuronal membrane with two complex lipid mixtures, characterized by phase coexistence and with negative charge confined to either the ordered or the disordered phase, respectively. To this purpose, we selected a five-component (DOPC/SM/DOPE/DOPS/chol) and a four-component (DOPC/SM/GM1/chol) lipid mixtures, which contained the main membrane lipid constituents and exhibited a phase separation with formation of ordered domains. We have compared the action of α-syn in monomeric form and at different concentrations (1 nM, 40 nM, and 200 nM) with respect to lipid systems with different composition and shape by AFM, QCM-D, and vesicle leakage experiments. The experiments coherently showed a higher stability of the membranes composed by the internal leaflet mixture to the interaction with α-syn. Damage to membranes made of the external leaflet mixture was detected in a concentration-dependent manner. Interestingly, the membrane damage was related to the fluidity of the lipid domains and not to the presence of negatively charged lipids.
Collapse
Affiliation(s)
- Samira Jadavi
- Nanoscopy, CHT Erzelli, Istituto Italiano di Tecnologia, Via Enrico Melen 83, Building B, 16152 Genova, Italy; Department of Physics, University of Genova, Via Dodecaneso 33, 16146 Genova, Italy
| | - Ester Canepa
- Department of Physics, University of Genova, Via Dodecaneso 33, 16146 Genova, Italy
| | - Alberto Diaspro
- Nanoscopy, CHT Erzelli, Istituto Italiano di Tecnologia, Via Enrico Melen 83, Building B, 16152 Genova, Italy; Department of Physics, University of Genova, Via Dodecaneso 33, 16146 Genova, Italy
| | - Claudio Canale
- Department of Physics, University of Genova, Via Dodecaneso 33, 16146 Genova, Italy
| | - Annalisa Relini
- Department of Physics, University of Genova, Via Dodecaneso 33, 16146 Genova, Italy.
| | - Silvia Dante
- Materials Characterization Facility, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy.
| |
Collapse
|
5
|
Krzystek TJ, Banerjee R, Thurston L, Huang J, Swinter K, Rahman SN, Falzone TL, Gunawardena S. Differential mitochondrial roles for α-synuclein in DRP1-dependent fission and PINK1/Parkin-mediated oxidation. Cell Death Dis 2021; 12:796. [PMID: 34404758 PMCID: PMC8371151 DOI: 10.1038/s41419-021-04046-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 07/18/2021] [Accepted: 07/19/2021] [Indexed: 01/18/2023]
Abstract
Mitochondria are highly dynamic organelles with strict quality control processes that maintain cellular homeostasis. Within axons, coordinated cycles of fission-fusion mediated by dynamin related GTPase protein (DRP1) and mitofusins (MFN), together with regulated motility of healthy mitochondria anterogradely and damaged/oxidized mitochondria retrogradely, control mitochondrial shape, distribution and size. Disruption of this tight regulation has been linked to aberrant oxidative stress and mitochondrial dysfunction causing mitochondrial disease and neurodegeneration. Although pharmacological induction of Parkinson's disease (PD) in humans/animals with toxins or in mice overexpressing α-synuclein (α-syn) exhibited mitochondrial dysfunction and oxidative stress, mice lacking α-syn showed resistance to mitochondrial toxins; yet, how α-syn influences mitochondrial dynamics and turnover is unclear. Here, we isolate the mechanistic role of α-syn in mitochondrial homeostasis in vivo in a humanized Drosophila model of Parkinson's disease (PD). We show that excess α-syn causes fragmented mitochondria, which persists with either truncation of the C-terminus (α-syn1-120) or deletion of the NAC region (α-synΔNAC). Using in vivo oxidation reporters Mito-roGFP2-ORP1/GRX1 and MitoTimer, we found that α-syn-mediated fragments were oxidized/damaged, but α-syn1-120-induced fragments were healthy, suggesting that the C-terminus is required for oxidation. α-syn-mediated oxidized fragments showed biased retrograde motility, but α-syn1-120-mediated healthy fragments did not, demonstrating that the C-terminus likely mediates the retrograde motility of oxidized mitochondria. Depletion/inhibition or excess DRP1-rescued α-syn-mediated fragmentation, oxidation, and the biased retrograde motility, indicating that DRP1-mediated fragmentation is likely upstream of oxidation and motility changes. Further, excess PINK/Parkin, two PD-associated proteins that function to coordinate mitochondrial turnover via induction of selective mitophagy, rescued α-syn-mediated membrane depolarization, oxidation and cell death in a C-terminus-dependent manner, suggesting a functional interaction between α-syn and PINK/Parkin. Taken together, our findings identify distinct roles for α-syn in mitochondrial homeostasis, highlighting a previously unknown pathogenic pathway for the initiation of PD.
Collapse
Affiliation(s)
- Thomas J Krzystek
- Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, 14260, USA
| | - Rupkatha Banerjee
- Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, 14260, USA
| | - Layne Thurston
- Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, 14260, USA
| | - JianQiao Huang
- Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, 14260, USA
| | - Kelsey Swinter
- Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, 14260, USA
| | - Saad Navid Rahman
- Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, 14260, USA
| | - Tomas L Falzone
- Instituto de Biología Celular y Neurociencias IBCN (CONICET-UBA), Universidad De Buenos Aires, Buenos Aires, Argentina.,Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA), Partner Institute of the Max Planck Society, Buenos Aires, Argentina
| | - Shermali Gunawardena
- Department of Biological Sciences, The State University of New York at Buffalo, Buffalo, NY, 14260, USA.
| |
Collapse
|
6
|
Scheibe C, Karreman C, Schildknecht S, Leist M, Hauser K. Synuclein Family Members Prevent Membrane Damage by Counteracting α-Synuclein Aggregation. Biomolecules 2021; 11:biom11081067. [PMID: 34439733 DOI: 10.3390/biom11081067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 07/09/2021] [Accepted: 07/15/2021] [Indexed: 01/09/2023] Open
Abstract
The 140 amino acid protein α-synuclein (αS) is an intrinsically disordered protein (IDP) with various roles and locations in healthy neurons that plays a key role in Parkinson's disease (PD). Contact with biomembranes can lead to α-helical conformations, but can also act as s seeding event for aggregation and a predominant β-sheet conformation. In PD patients, αS is found to aggregate in various fibrillary structures, and the shift in aggregation and localization is associated with disease progression. Besides full-length αS, several related polypeptides are present in neurons. The role of many αS-related proteins in the aggregation of αS itself is not fully understood Two of these potential aggregation modifiers are the αS splicing variant αS Δexon3 (Δ3) and the paralog β-synuclein (βS). Here, polarized ATR-FTIR spectroscopy was used to study the membrane interaction of these proteins individually and in various combinations. The method allowed a continuous monitoring of both the lipid structure of biomimetic membranes and the aggregation state of αS and related proteins. The use of polarized light also revealed the orientation of secondary structure elements. While αS led to a destruction of the lipid membrane upon membrane-catalyzed aggregation, βS and Δ3 aggregated significantly less, and they did not harm the membrane. Moreover, the latter proteins reduced the membrane damage triggered by αS. There were no major differences in the membrane interaction for the different synuclein variants. In combination, these observations suggest that the formation of particular protein aggregates is the major driving force for αS-driven membrane damage. The misbalance of αS, βS, and Δ3 might therefore play a crucial role in neurodegenerative disease.
Collapse
Affiliation(s)
- Christian Scheibe
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | | | - Stefan Schildknecht
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
- Department of Life Sciences, Albstadt-Sigmaringen University of Applied Sciences, 72488 Sigmaringen, Germany
| | - Marcel Leist
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Karin Hauser
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| |
Collapse
|
7
|
Neurons and Glia Interplay in α-Synucleinopathies. Int J Mol Sci 2021; 22:ijms22094994. [PMID: 34066733 PMCID: PMC8125822 DOI: 10.3390/ijms22094994] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/29/2021] [Accepted: 05/04/2021] [Indexed: 11/16/2022] Open
Abstract
Accumulation of the neuronal presynaptic protein alpha-synuclein within proteinaceous inclusions represents the key histophathological hallmark of a spectrum of neurodegenerative disorders, referred to by the umbrella term a-synucleinopathies. Even though alpha-synuclein is expressed predominantly in neurons, pathological aggregates of the protein are also found in the glial cells of the brain. In Parkinson's disease and dementia with Lewy bodies, alpha-synuclein accumulates mainly in neurons forming the Lewy bodies and Lewy neurites, whereas in multiple system atrophy, the protein aggregates mostly in the glial cytoplasmic inclusions within oligodendrocytes. In addition, astrogliosis and microgliosis are found in the synucleinopathy brains, whereas both astrocytes and microglia internalize alpha-synuclein and contribute to the spread of pathology. The mechanisms underlying the pathological accumulation of alpha-synuclein in glial cells that under physiological conditions express low to non-detectable levels of the protein are an area of intense research. Undoubtedly, the presence of aggregated alpha-synuclein can disrupt glial function in general and can contribute to neurodegeneration through numerous pathways. Herein, we summarize the current knowledge on the role of alpha-synuclein in both neurons and glia, highlighting the contribution of the neuron-glia connectome in the disease initiation and progression, which may represent potential therapeutic target for a-synucleinopathies.
Collapse
|
8
|
McClain SM, Ojoawo AM, Lin W, Rienstra CM, Murphy CJ. Interaction of Alpha-Synuclein and Its Mutants with Rigid Lipid Vesicle Mimics of Varying Surface Curvature. ACS NANO 2020; 14:10153-10167. [PMID: 32672441 DOI: 10.1021/acsnano.0c03420] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Abnormal aggregation of alpha-synuclein (α-syn), an intrinsically disordered neuronal protein, is strongly implicated in the development of Parkinson's disease. Efforts to better understand α-syn's native function and its pathogenic role in neurodegeneration have revealed that the protein interacts with anionic lipid vesicles via adoption of an amphipathic α-helical structure; however, the ability of α-syn to remodel lipid membranes has made it difficult to decipher the role of vesicle surface curvature in protein binding behavior. In this study, sodium dodecyl sulfate (SDS)-coated gold nanoparticles (AuNPs), which mimic bilayer vesicle architecture, were synthesized in order to conduct a systematic investigation into the binding interaction of α-syn and two of its mutants (A30P and E46K) with rigid lipid vesicle mimics of defined surface curvature. By incorporating a rigid AuNP core (∼10-100 nm), the ability of α-syn to remodel the vesicle mimics was removed and their surface curvature could be fixed. Proteomics studies showed that, upon binding of free α-syn to the surface of SDS-AuNPs, the N-terminus of α-syn became less solvent accessible, whereas its C-terminus became more accessible. Interestingly, α-syn's non-amyloid-β component (NAC) region also exhibited increased solvent accessibility, suggesting that α-syn bound to rigid vesicle-like structures could possess heightened aggregation propensity and therefore pathogenicity. Additionally, both the A30P and E46K mutations were found to adopt distinct binding modes on the mimics' surface. In contrast with previous reports, similar binding affinities were observed for WT, A30P, and E46K α-syn toward SDS-AuNPs of all sizes, indicating the potential importance of vesicle deformability in determining α-syn binding behavior.
Collapse
Affiliation(s)
- Sophia M McClain
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Adedolapo M Ojoawo
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Wayne Lin
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Chad M Rienstra
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Carle-Illinois College of Medicine, University of Illinois at Urbana-Champaign, Champaign, Illinois 61820, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Catherine J Murphy
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| |
Collapse
|
9
|
A series of helical α-synuclein fibril polymorphs are populated in the presence of lipid vesicles. NPJ PARKINSONS DISEASE 2020; 6:17. [PMID: 32864427 PMCID: PMC7438318 DOI: 10.1038/s41531-020-00122-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 07/22/2020] [Indexed: 12/12/2022]
Abstract
α-Synuclein (αS) deposition is a defining characteristic of Parkinson’s disease (PD) pathology, and other synucleinopathies. αS aggregates in disease, leading to the generation of neuronal inclusions known as Lewy bodies. These accumulate in the cytoplasmic space of dopaminergic neurons in the substantia nigra pars compacta region of the brain, causing cell death, resulting in decreased dopamine levels, and ultimately PD symptoms. To date, a significant proportion of structural information has arisen from in vitro studies using recombinantly purified forms of the protein, often failing to acknowledge that αS is natively located in the presence of phospholipids, where it likely plays a direct role in regulating synaptic vesicle function and neurotransmission. Here we present a series of macromolecular αS assemblies not previously described that form in the presence of lipid vesicles. These fibrillar structures are striking in both their large size relative to those previously reported and by their varying helical content, from ribbons to wave-like helices of long pitch shortening to those more compact and bulkier. These studies provide the foundation for more detailed structural analysis, and may offer new possibilities to further define disease-relevant versions of the protein that are accessible to pharmacological intervention.
Collapse
|
10
|
Abstract
α-Synuclein is a neuronal protein with an ill-defined biological function that is central to Parkinson’s disease etiology. While considered to be involved in exocytosis, how α-synuclein facilitates synaptic vesicle fusion and release remains an open question. To address this, we investigated α-synuclein–lipid interactions at the plasma membrane through the technique of cellular unroofing, which uncovers an intact basal membrane. We conclusively show that α-synuclein is recruited to exocytic sites, preferring liquid-ordered lipid domains. Importantly, heterogeneous populations of α-synuclein conformers are revealed by measurements of fluorescence lifetime distributions, which are not adequately described by current models of α-synuclein structures. Membrane-bound α-synuclein is conformationally dynamic, exquisitely sensitive to lipid/protein composition, enabling the protein to carry out its function. Parkinson’s disease is associated with α-synuclein (α-syn), a cytosolic protein enriched in presynaptic terminals. The biological function of α-syn remains elusive; however, increasing evidence suggests that the protein is involved in the regulation of synaptic vesicle fusion, signifying the importance of α-syn–lipid interactions. We show that α-syn preferentially binds to GM1-rich, liquid-ordered lipid domains on cytoplasmic membranes by using unroofed cells, which encapsulates lipid complexity and cellular topology. Moreover, proteins (Rab3a, syntaxin-1A, and VAMP2) involved in exocytosis also localize with α-syn, supporting its proposed functional role in exocytosis. To investigate how these lipid/protein interactions influence α-syn at the residue level, α-syn was derivatized with an environmentally sensitive fluorophore (7-nitrobenz-2-oxa-1,3-diazol-4-yl [NBD]) at different N- and C-terminal sites. Measurements of NBD fluorescence lifetime distributions reveal that α-syn adopts a multitude of membrane-bound conformations, which were not recapitulated in simple micelle or vesicle models, indicating an exquisite sensitivity of the protein to the complex lipid environment. Interestingly, these data also suggest the participation of the C terminus in membrane localization, which is generally overlooked and thus emphasize the need to use cellularly derived and biologically relevant membranes for biophysical characterization. Collectively, our results demonstrate that α-syn is more conformationally dynamic at the membrane interface than previously appreciated, which may be important for both its physiological and pathological functions.
Collapse
|
11
|
Perera YR, Hill RA, Fitzkee NC. Protein Interactions with Nanoparticle Surfaces: Highlighting Solution NMR Techniques. Isr J Chem 2019; 59:962-979. [PMID: 34045771 PMCID: PMC8152826 DOI: 10.1002/ijch.201900080] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 09/02/2019] [Indexed: 12/14/2022]
Abstract
In the last decade, nanoparticles (NPs) have become a key tool in medicine and biotechnology as drug delivery systems, biosensors and diagnostic devices. The composition and surface chemistry of NPs vary based on the materials used: typically organic polymers, inorganic materials, or lipids. Nanoparticle classes can be further divided into sub-categories depending on the surface modification and functionalization. These surface properties matter when NPs are introduced into a physiological environment, as they will influence how nucleic acids, lipids, and proteins will interact with the NP surface. While small-molecule interactions are easily probed using NMR spectroscopy, studying protein-NP interactions using NMR introduces several challenges. For example, globular proteins may have a perturbed conformation when attached to a foreign surface, and the size of NP-protein conjugates can lead to excessive line broadening. Many of these challenges have been addressed, and NMR spectroscopy is becoming a mature technique for in situ analysis of NP binding behavior. It is therefore not surprising that NMR has been applied to NP systems and has been used to study biomolecules on NP surfaces. Important considerations include corona composition, protein behavior, and ligand architecture. These features are difficult to resolve using classical surface and material characterization strategies, and NMR provides a complementary avenue of characterization. In this review, we examine how solution NMR can be combined with other analytical techniques to investigate protein behavior on NP surfaces.
Collapse
Affiliation(s)
- Y Randika Perera
- Department of Chemistry, Mississippi State University, Mississippi State, MS 39762, USA
| | - Rebecca A Hill
- Department of Chemistry, Mississippi State University, Mississippi State, MS 39762, USA
| | - Nicholas C Fitzkee
- Department of Chemistry, Mississippi State University, Mississippi State, MS 39762, USA
| |
Collapse
|
12
|
Conformation change of α-synuclein(61-95) at the air-water interface and quantitative measurement of the tilt angle of the axis of its α-helix by multiple angle incidence resolution spectroscopy. Colloids Surf B Biointerfaces 2019; 183:110401. [DOI: 10.1016/j.colsurfb.2019.110401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 07/16/2019] [Accepted: 07/26/2019] [Indexed: 11/18/2022]
|
13
|
Mesa-Herrera F, Taoro-González L, Valdés-Baizabal C, Diaz M, Marín R. Lipid and Lipid Raft Alteration in Aging and Neurodegenerative Diseases: A Window for the Development of New Biomarkers. Int J Mol Sci 2019; 20:E3810. [PMID: 31382686 PMCID: PMC6696273 DOI: 10.3390/ijms20153810] [Citation(s) in RCA: 105] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/1970] [Revised: 07/23/2019] [Accepted: 07/24/2019] [Indexed: 12/13/2022] Open
Abstract
Lipids in the brain are major components playing structural functions as well as physiological roles in nerve cells, such as neural communication, neurogenesis, synaptic transmission, signal transduction, membrane compartmentalization, and regulation of gene expression. Determination of brain lipid composition may provide not only essential information about normal brain functioning, but also about changes with aging and diseases. Indeed, deregulations of specific lipid classes and lipid homeostasis have been demonstrated in neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). Furthermore, recent studies have shown that membrane microdomains, named lipid rafts, may change their composition in correlation with neuronal impairment. Lipid rafts are key factors for signaling processes for cellular responses. Lipid alteration in these signaling platforms may correlate with abnormal protein distribution and aggregation, toxic cell signaling, and other neuropathological events related with these diseases. This review highlights the manner lipid changes in lipid rafts may participate in the modulation of neuropathological events related to AD and PD. Understanding and characterizing these changes may contribute to the development of novel and specific diagnostic and prognostic biomarkers in routinely clinical practice.
Collapse
Affiliation(s)
- Fátima Mesa-Herrera
- Laboratory of Membrane Physiology and Biophysics, Department of Animal Biology, Edaphology and Geology
| | - Lucas Taoro-González
- Laboratory of Cellular Neurobiology, Department of Basic Medical Sciences, Section of Medicine, Faculty of Health Sciences, University of La Laguna, Sta. Cruz de Tenerife 38200, Spain
| | - Catalina Valdés-Baizabal
- Laboratory of Cellular Neurobiology, Department of Basic Medical Sciences, Section of Medicine, Faculty of Health Sciences, University of La Laguna, Sta. Cruz de Tenerife 38200, Spain
| | - Mario Diaz
- Laboratory of Membrane Physiology and Biophysics, Department of Animal Biology, Edaphology and Geology
- Associate Research Unit ULL-CSIC "Membrane Physiology and Biophysics in Neurodegenerative and Cancer Diseases", University of La Laguna, Sta. Cruz de Tenerife 38200, Spain
| | - Raquel Marín
- Laboratory of Cellular Neurobiology, Department of Basic Medical Sciences, Section of Medicine, Faculty of Health Sciences, University of La Laguna, Sta. Cruz de Tenerife 38200, Spain.
- Associate Research Unit ULL-CSIC "Membrane Physiology and Biophysics in Neurodegenerative and Cancer Diseases", University of La Laguna, Sta. Cruz de Tenerife 38200, Spain.
| |
Collapse
|
14
|
Alpha-Synuclein RNA Expression is Increased in Major Depression. Int J Mol Sci 2019; 20:ijms20082029. [PMID: 31027150 PMCID: PMC6515395 DOI: 10.3390/ijms20082029] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 04/18/2019] [Accepted: 04/20/2019] [Indexed: 01/08/2023] Open
Abstract
Alpha-synuclein (SNCA) is a small membrane protein that plays an important role in neuro-psychiatric diseases. It is best known for its abnormal subcellular aggregation in Lewy bodies that serves as a hallmark of Parkinson’s disease (PD). Due to the high comorbidity of PD with depression, we investigated the role of SNCA in patients suffering from major depressive disorder (MDD). SNCA mRNA expression levels were analyzed in peripheral blood cells of MDD patients and a healthy control group. SNCA mRNA expression was positively correlated with severity of depression as indicated by psychometric assessment. We found a significant increase in SNCA mRNA expression levels in severely depressed patients compared with controls. Thus, SNCA analysis could be a helpful target in the search for biomarkers of MDD.
Collapse
|
15
|
Abstract
α-Synuclein is an abundant neuronal protein which localizes predominantly to presynaptic terminals, and is strongly linked genetically and pathologically to Parkinson's disease and other neurodegenerative diseases. While the accumulation of α-synuclein in the form of misfolded oligomers and large aggregates defines multiple neurodegenerative diseases called "synucleinopathies", its cellular function has remained largely unclear, and is the subject of intense investigation. In this review, I focus on the structural characteristics of α-synuclein, its cellular and subcellular localization, and discuss how this relates to its function in neurons, in particular at the neuronal synapse.
Collapse
Affiliation(s)
- Jacqueline Burré
- Appel Institute for Alzheimer’s Disease Research, Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, New York, NY, USA
| |
Collapse
|
16
|
Bédard L, Lefèvre T, Morin-Michaud É, Auger M. Besides Fibrillization: Putative Role of the Peptide Fragment 71–82 on the Structural and Assembly Behavior of α-Synuclein. Biochemistry 2014; 53:6463-72. [DOI: 10.1021/bi5008707] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Laurie Bédard
- Department of Chemistry,
Regroupement Québécois de Recherche sur la Fonction,
la Structure et l’Ingénierie des Protéines (PROTEO),
Centre de Recherche sur les Matériaux Avancés (CERMA),
Centre Québécois sur les Matériaux Fonctionnels
(CQMF), Université Laval, Québec, Québec G1V 0A6, Canada
| | - Thierry Lefèvre
- Department of Chemistry,
Regroupement Québécois de Recherche sur la Fonction,
la Structure et l’Ingénierie des Protéines (PROTEO),
Centre de Recherche sur les Matériaux Avancés (CERMA),
Centre Québécois sur les Matériaux Fonctionnels
(CQMF), Université Laval, Québec, Québec G1V 0A6, Canada
| | - Émilie Morin-Michaud
- Department of Chemistry,
Regroupement Québécois de Recherche sur la Fonction,
la Structure et l’Ingénierie des Protéines (PROTEO),
Centre de Recherche sur les Matériaux Avancés (CERMA),
Centre Québécois sur les Matériaux Fonctionnels
(CQMF), Université Laval, Québec, Québec G1V 0A6, Canada
| | - Michèle Auger
- Department of Chemistry,
Regroupement Québécois de Recherche sur la Fonction,
la Structure et l’Ingénierie des Protéines (PROTEO),
Centre de Recherche sur les Matériaux Avancés (CERMA),
Centre Québécois sur les Matériaux Fonctionnels
(CQMF), Université Laval, Québec, Québec G1V 0A6, Canada
| |
Collapse
|
17
|
Exogenous α-synuclein decreases raft partitioning of Cav2.2 channels inducing dopamine release. J Neurosci 2014; 34:10603-15. [PMID: 25100594 DOI: 10.1523/jneurosci.0608-14.2014] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
α-Synuclein is thought to regulate neurotransmitter release through multiple interactions with presynaptic proteins, cytoskeletal elements, ion channels, and synaptic vesicles membrane. α-Synuclein is abundant in the presynaptic compartment, and its release from neurons and glia has been described as responsible for spreading of α-synuclein-derived pathology. α-Synuclein-dependent dysregulation of neurotransmitter release might occur via its action on surface-exposed calcium channels. Here, we provide electrophysiological and biochemical evidence to show that α-synuclein, applied to rat neurons in culture or striatal slices, selectively activates Cav2.2 channels, and said activation correlates with increased neurotransmitter release. Furthermore, in vivo perfusion of α-synuclein into the striatum also leads to acute dopamine release. We further demonstrate that α-synuclein reduces the amount of plasma membrane cholesterol and alters the partitioning of Cav2.2 channels, which move from raft to cholesterol-poor areas of the plasma membrane. We provide evidence for a novel mechanism through which α-synuclein acts from the extracellular milieu to modulate neurotransmitter release and propose a unifying hypothesis for the mechanism of α-synuclein action on multiple targets: the reorganization of plasma membrane microdomains.
Collapse
|
18
|
Jiang Z, de Messieres M, Lee JC. Membrane remodeling by α-synuclein and effects on amyloid formation. J Am Chem Soc 2013; 135:15970-3. [PMID: 24099487 PMCID: PMC3859146 DOI: 10.1021/ja405993r] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
α-Synuclein (α-Syn), an intrinsically disordered protein, is associated with Parkinson's disease. Though molecular pathogenic mechanisms are ill-defined, mounting evidence connects its amyloid forming and membrane binding propensities to disease etiology. Contrary to recent data suggesting that membrane remodeling by α-syn involves anionic phospholipids and helical structure, we discovered that the protein deforms vesicles with no net surface charge (phosphatidylcholine, PC) into tubules (average diameter ∼20 nm). No discernible secondary structural changes were detected by circular dichroism spectroscopy upon the addition of vesicles. Notably, membrane remodeling inhibits α-syn amyloid formation affecting both lag and growth phases. Using five single tryptophan variants and time-resolved fluorescence anisotropy measurements, we determined that α-syn influences bilayer structure with surprisingly weak interaction and no site specificity (partition constant, Kp ∼ 300 M(-1)). Vesicle deformation by α-syn under a variety of different lipid/protein conditions is characterized via transmission electron microscopy. As cellular membranes are enriched in PC lipids, these results support possible biological consequences for α-syn induced membrane remodeling related to both function and pathogenesis.
Collapse
Affiliation(s)
- Zhiping Jiang
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, United States
| | - Michel de Messieres
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, United States
| | - Jennifer C. Lee
- Laboratory of Molecular Biophysics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, United States
| |
Collapse
|
19
|
Solid-state ¹³C NMR reveals annealing of raft-like membranes containing cholesterol by the intrinsically disordered protein α-Synuclein. J Mol Biol 2013; 425:2973-87. [PMID: 23583776 DOI: 10.1016/j.jmb.2013.04.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Revised: 03/14/2013] [Accepted: 04/02/2013] [Indexed: 11/20/2022]
Abstract
Misfolding and aggregation of the intrinsically disordered protein α-Synuclein (αS) in Lewy body plaques are characteristic markers of late-stage Parkinson's disease. It is well established that membrane binding is initiated at the N-terminus of the protein and affects biasing of conformational ensembles of αS. However, little is understood about the effect of αS on the membrane lipid bilayer. One hypothesis is that intrinsically disordered αS alters the structural properties of the membrane, thereby stabilizing the bilayer against fusion. Here, we used two-dimensional (13)C separated local-field NMR to study interaction of the wild-type α-Synuclein (wt-αS) or its N-terminal (1-25) amino acid sequence (N-αS) with a cholesterol-enriched ternary membrane system. This lipid bilayer mimics cellular raft-like domains in the brain that are proposed to be involved in neuronal membrane fusion. The two-dimensional dipolar-recoupling pulse sequence DROSS (dipolar recoupling on-axis with scaling and shape preservation) was implemented to measure isotropic (13)C chemical shifts and (13)C-(1)H residual dipolar couplings under magic-angle spinning. Site-specific changes in NMR chemical shifts and segmental order parameters indicate that both wt-αS and N-αS bind to the membrane interface and change lipid packing within raft-like membranes. Mean-torque modeling of (13)C-(1)H NMR order parameters shows that αS induces a remarkable thinning of the bilayer (≈6Å), accompanied by an increase in phospholipid cross-sectional area (≈10Å(2)). This perturbation is characterized as membrane annealing and entails structural remodeling of the raft-like liquid-ordered phase. We propose this process is implicated in regulation of synaptic membrane fusion that may be altered by aggregation of αS in Parkinson's disease.
Collapse
|
20
|
Herbert AP, Riesen M, Bloxam L, Kosmidou E, Wareing BM, Johnson JR, Phelan MM, Pennington SR, Lian LY, Morgan A. NMR structure of Hsp12, a protein induced by and required for dietary restriction-induced lifespan extension in yeast. PLoS One 2012; 7:e41975. [PMID: 22848679 PMCID: PMC3407059 DOI: 10.1371/journal.pone.0041975] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2012] [Accepted: 06/26/2012] [Indexed: 11/19/2022] Open
Abstract
Dietary restriction (DR) extends lifespan in yeast, worms, flies and mammals, suggesting that it may act via conserved processes. However, the downstream mechanisms by which DR increases lifespan remain unclear. We used a gel based proteomic strategy to identify proteins whose expression was induced by DR in yeast and thus may correlate with longevity. One protein up-regulated by DR was Hsp12, a small heat shock protein induced by various manipulations known to retard ageing. Lifespan extension by growth on 0.5% glucose (DR) was abolished in an hsp12Δ strain, indicating that Hsp12 is essential for the longevity effect of DR. In contrast, deletion of HSP12 had no effect on growth under DR conditions or a variety of environmental stresses, indicating that the effect of Hsp12 on lifespan is not due to increased general stress resistance. Unlike other small heat shock proteins, recombinant Hsp12 displayed negligible in vitro molecular chaperone activity, suggesting that its cellular function does not involve preventing protein aggregation. NMR analysis indicated that Hsp12 is monomeric and intrinsically unfolded in solution, but switches to a 4-helical conformation upon binding to membrane-mimetic SDS micelles. The structure of micelle-bound Hsp12 reported here is consistent with its recently proposed function as a membrane-stabilising 'lipid chaperone'. Taken together, our data suggest that DR-induced Hsp12 expression contributes to lifespan extension, possibly via membrane alterations.
Collapse
Affiliation(s)
- Andrew P. Herbert
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
- NMR Centre for Structural Biology, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Michèle Riesen
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Leanne Bloxam
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Effie Kosmidou
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Brian M. Wareing
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - James R. Johnson
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Marie M. Phelan
- NMR Centre for Structural Biology, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Stephen R. Pennington
- University College Dublin Conway Institute of Biomedical and Biomolecular Research, University College Dublin, Dublin, Ireland
| | - Lu-Yun Lian
- NMR Centre for Structural Biology, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Alan Morgan
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| |
Collapse
|
21
|
Chu Y, Morfini GA, Langhamer LB, He Y, Brady ST, Kordower JH. Alterations in axonal transport motor proteins in sporadic and experimental Parkinson's disease. ACTA ACUST UNITED AC 2012; 135:2058-73. [PMID: 22719003 DOI: 10.1093/brain/aws133] [Citation(s) in RCA: 211] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The progressive loss of the nigrostriatal pathway is a distinguishing feature of Parkinson's disease. As terminal field loss seems to precede cell body loss, we tested whether alterations of axonal transport motor proteins would be early features in Parkinson's disease. There was a decline in axonal transport motor proteins in sporadic Parkinson's disease that preceded other well-known nigral cell-related pathology such as phenotypic downregulation of dopamine. Reductions in conventional kinesin levels precede the alterations in dopaminergic phenotypic markers (tyrosine hydroxylase) in the early stages of Parkinson's disease. This reduction was significantly greater in nigral neurons containing α-synuclein inclusions. Unlike conventional kinesin, reductions in the levels of the cytoplasmic dynein light chain Tctex type 3 subunit were only observed at late Parkinson's disease stages. Reductions in levels of conventional kinesin and cytoplasmic dynein subunits were recapitulated in a rat genetic Parkinson's disease model based on over-expression of human mutant α-synuclein (A30P). Together, our data suggest that α-synuclein aggregation is a key feature associated with reductions of axonal transport motor proteins in Parkinson's disease and support the hypothesis that dopaminergic neurodegeneration following a 'dying-back' pattern involving axonal transport disruption.
Collapse
Affiliation(s)
- Yaping Chu
- Department of Neurological Sciences, Rush University Medical Centre, 1735 West Harrison Street, Chicago, IL 60612, USA
| | | | | | | | | | | |
Collapse
|
22
|
Liu G, Aliaga L, Cai H. α-synuclein, LRRK2 and their interplay in Parkinson's disease. FUTURE NEUROLOGY 2012; 7:145-153. [PMID: 22563296 DOI: 10.2217/fnl.12.2] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Of the various genetic factors contributing to the pathogenesis of Parkinson's disease (PD), only mutations in α-synuclein (α-syn) and LRRK2 genes cause clinical and neuropathological phenotypes closely resembling the sporadic cases. Therefore, studying the pathophysiological functions of these two PD-related genes is particularly informative in understanding the underlying molecular pathogenic mechanism of the disease. PD-related missense and multiplication mutations in α-syn may cause both early- and late-onset PD, whereas various PD-related LRRK2 missense mutations may contribute to the more common late-onset PD. While intensive studies have been carried out to elucidate the pathogenic properties of PD-related mutant α-syn and LRRK2, our knowledge of their normal functions and their potential genetic interplay remains rudimental. In this review, we summarize the progress made regarding the pathophysiological functions of α-syn, LRRK2 and their interaction in PD, based on the available literature and our unpublished observations.
Collapse
Affiliation(s)
- Guoxiang Liu
- Transgenics Section, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | |
Collapse
|
23
|
Pfefferkorn CM, Jiang Z, Lee JC. Biophysics of α-synuclein membrane interactions. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1818:162-71. [PMID: 21819966 PMCID: PMC3249522 DOI: 10.1016/j.bbamem.2011.07.032] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 07/20/2011] [Accepted: 07/21/2011] [Indexed: 12/14/2022]
Abstract
Membrane proteins participate in nearly all cellular processes; however, because of experimental limitations, their characterization lags far behind that of soluble proteins. Peripheral membrane proteins are particularly challenging to study because of their inherent propensity to adopt multiple and/or transient conformations in solution and upon membrane association. In this review, we summarize useful biophysical techniques for the study of peripheral membrane proteins and their application in the characterization of the membrane interactions of the natively unfolded and Parkinson's disease (PD) related protein, α-synuclein (α-syn). We give particular focus to studies that have led to the current understanding of membrane-bound α-syn structure and the elucidation of specific membrane properties that affect α-syn-membrane binding. Finally, we discuss biophysical evidence supporting a key role for membranes and α-syn in PD pathogenesis. This article is part of a Special Issue entitled: Membrane protein structure and function.
Collapse
Affiliation(s)
- Candace M. Pfefferkorn
- Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Zhiping Jiang
- Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Jennifer C. Lee
- Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892
| |
Collapse
|
24
|
Abstract
AbstractGenetic, neuropathological and biochemical evidence implicates α-synuclein, a 140 amino acid presynaptic neuronal protein, in the pathogenesis of Parkinson’s disease and other neurodegenerative disorders. The aggregated protein inclusions mainly containing aberrant α-synuclein are widely accepted as morphological hallmarks of α-synucleinopathies, but their composition and location vary between disorders along with neuronal networks affected. α-Synuclein exists physiologically in both soluble and membran-bound states, in unstructured and α-helical conformations, respectively, while posttranslational modifications due to proteostatic deficits are involved in β-pleated aggregation resulting in formation of typical inclusions. The physiological function of α-synuclein and its role linked to neurodegeneration, however, are incompletely understood. Soluble oligomeric, not fully fibrillar α-synuclein is thought to be neurotoxic, main targets might be the synapse, axons and glia. The effects of aberrant α-synuclein include alterations of calcium homeostasis, mitochondrial dysfunction, oxidative and nitric injuries, cytoskeletal effects, and neuroinflammation. Proteasomal dysfunction might be a common mechanism in the pathogenesis of neuronal degeneration in α-synucleinopathies. However, how α-synuclein induces neurodegeneration remains elusive as its physiological function. Genome wide association studies demonstrated the important role for genetic variants of the SNCA gene encoding α-synuclein in the etiology of Parkinson’s disease, possibly through effects on oxidation, mitochondria, autophagy, and lysosomal function. The neuropathology of synucleinopathies and the role of α-synuclein as a potential biomarker are briefly summarized. Although animal models provided new insights into the pathogenesis of Parkinson disease and multiple system atrophy, most of them do not adequately reproduce the cardinal features of these disorders. Emerging evidence, in addition to synergistic interactions of α-synuclein with various pathogenic proteins, suggests that prionlike induction and seeding of α-synuclein could lead to the spread of the pathology and disease progression. Intervention in the early aggregation pathway, aberrant cellular effects, or secretion of α-synuclein might be targets for neuroprotection and disease-modifying therapy.
Collapse
|
25
|
Breydo L, Wu JW, Uversky VN. Α-synuclein misfolding and Parkinson's disease. Biochim Biophys Acta Mol Basis Dis 2011; 1822:261-85. [PMID: 22024360 DOI: 10.1016/j.bbadis.2011.10.002] [Citation(s) in RCA: 447] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 08/26/2011] [Accepted: 10/03/2011] [Indexed: 12/21/2022]
Abstract
Substantial evidence links α-synuclein, a small highly conserved presynaptic protein with unknown function, to both familial and sporadic Parkinson's disease (PD). α-Synuclein has been identified as the major component of Lewy bodies and Lewy neurites, the characteristic proteinaceous deposits that are the hallmarks of PD. α-Synuclein is a typical intrinsically disordered protein, but can adopt a number of different conformational states depending on conditions and cofactors. These include the helical membrane-bound form, a partially-folded state that is a key intermediate in aggregation and fibrillation, various oligomeric species, and fibrillar and amorphous aggregates. The molecular basis of PD appears to be tightly coupled to the aggregation of α-synuclein and the factors that affect its conformation. This review examines the different aggregation states of α-synuclein, the molecular mechanism of its aggregation, and the influence of environmental and genetic factors on this process.
Collapse
Affiliation(s)
- Leonid Breydo
- Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, FL 33612, USA
| | | | | |
Collapse
|
26
|
Ho GJ, Liang W, Waragai M, Sekiyama K, Masliah E, Hashimoto M. Bridging molecular genetics and biomarkers in lewy body and related disorders. Int J Alzheimers Dis 2011; 2011:842475. [PMID: 21760990 PMCID: PMC3132544 DOI: 10.4061/2011/842475] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Accepted: 04/20/2011] [Indexed: 12/16/2022] Open
Abstract
Recent advances have been made in defining the genetic and molecular basis of dementia with Lewy bodies (DLBs) and related neurodegenerative disorders such as Parkinson's disease (PD) and Parkinson's disease dementia (PDD) which comprise the spectrum of “Lewy body disorders” (LBDs). The genetic alterations and underlying disease mechanisms in the LBD overlap substantially, suggesting common disease mechanisms. As with the other neurodegenerative dementias, early diagnosis in LBD or even identification prior to symptom onset is key to developing effective therapeutic strategies, but this is dependent upon the development of robust, specific, and sensitive biomarkers as diagnostic tools and therapeutic endpoints. Recently identified mutations in the synucleins and other relevant genes in PD and DLB as well as related biomolecular pathways suggest candidate markers from biological fluids and imaging modalities that reflect the underlying disease mechanisms. In this context, several promising biomarkers for the LBD have already been identified and examined, while other intriguing possible candidates have recently emerged. Challenges remain in defining their correlation with pathological processes and their ability to detect DLB and related disorders, and perhaps a combined array of biomarkers may be needed to distinguish various LBDs.
Collapse
Affiliation(s)
- Gilbert J Ho
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093-0624, USA
| | | | | | | | | | | |
Collapse
|
27
|
NACP-Rep1 relates to Beck Depression Inventory scores in healthy humans. J Mol Neurosci 2011; 44:41-7. [PMID: 21271299 DOI: 10.1007/s12031-011-9493-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Accepted: 01/11/2011] [Indexed: 10/18/2022]
Abstract
Alpha-synuclein (SNCA) is associated with a range of psychiatric diseases including neurodegeneration, alcohol craving, and depression. It regulates cellular homeostasis by virtue of its ability to interfere in dopaminergic, serotonergic, and noradrenergic pathways. To date, it is unclear whether the previously described association between SNCA and depressive symptomatology is limited to females with eating disorders or whether it could be extended to include healthy individuals. We included 105 women and 108 men. Genetic data and mRNA expression analyses were drawn from peripheral blood and the severity of depressive symptoms was quantified by the Beck's Depression Inventory (BDI). We found a significant association between the NACP-Rep1 length polymorphism and the BDI score (p = 0.004). Moreover, there was a significant gender dimorphism regarding mRNA expression of SNCA (p = 0.011). Our analysis revealed no further association between the In4 polymorphism or between the mRNA expression of SNCA and the BDI score. Since this investigation was limited to healthy individuals, conclusions concerning depression according to ICD-10 or DSM-IV cannot be drawn. The reported results may contribute to a better understanding of the molecular mechanisms linked to depressive symptoms.
Collapse
|
28
|
Wang P, Jiang S, Cui Y, Yue Z, Su C, Sun J, Sheng S, Tian J. The n-terminal 5-MER peptide analogue P165 of amyloid precursor protein exerts protective effects on SH-SY5Y cells and rat hippocampus neuronal synapses. Neuroscience 2010; 173:169-78. [PMID: 21055450 DOI: 10.1016/j.neuroscience.2010.10.069] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 10/08/2010] [Accepted: 10/26/2010] [Indexed: 11/28/2022]
Abstract
The disturbance of the insulin-signaling pathway plays an important role in Alzheimer's disease. Resistance to insulin signaling renders neurons energy-deficient and vulnerable to oxidization or other metabolic insults and impairs synaptic plasticity. In search of neuroprotective drugs, we synthesized a peptide analogue, P165, an active domain of the soluble amyloid precursor protein, which is resistant to degradation and is suitable for oral administration in a clinical setting. Initially, we confirmed that P165 can protect cells from streptozotocin-caused damage and stimulate cell outgrowth using cultured SH-SY5Y cell lines treated with streptozotocin. P165 significantly reduced lactate dehydrogenase leakage from damaged cells, thereby rescuing cell energy production. Insulin signaling such as insulin receptor substrate-1 (IRS-1) and phosphoinositide 3-kinase (PI3K) proteins were upregulated to stimulate cell survival and growth. We proceeded to investigate the effect of P165 on streptozotocin-treated Alzheimer's disease (AD) rats. The data showed that P165 protected synaptic loss and dysfunction by increasing synaptophysin and PSD-95 (post synaptic density-95), while simultaneously decreasing α-synuclein expression. Moreover, animal behavior testing clearly showed that P165 increased rats' learning and memory activity. Overall, these results constitute evidence that peptide analogue 165 may protect synapse and improve learning and memory ability in AD.
Collapse
Affiliation(s)
- P Wang
- Key Laboratory of Chinese Internal Medicine (Beijing University of Chinese Medicine), Ministry of Education, Beijing 100700, People's Republic of China
| | | | | | | | | | | | | | | |
Collapse
|
29
|
Georgieva ER, Ramlall TF, Borbat PP, Freed JH, Eliezer D. The lipid-binding domain of wild type and mutant alpha-synuclein: compactness and interconversion between the broken and extended helix forms. J Biol Chem 2010; 285:28261-74. [PMID: 20592036 DOI: 10.1074/jbc.m110.157214] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Alpha-synuclein (alphaS) is linked to Parkinson disease through its deposition in an amyloid fibril form within Lewy Body deposits, and by the existence of three alphaS point mutations that lead to early onset autosomal dominant Parkinsonism. The normal function of alphaS is thought to be linked to the ability of the protein to bind to the surface of synaptic vesicles. Upon binding to vesicles, alphaS undergoes a structural reorganization from a dynamic and disordered ensemble to a conformation consisting of a long extended helix. In the presence of small spheroidal detergent micelles, however, this extended helix conformation can convert into a broken helix state, in which a region near the middle of the helix unwinds to form a linker between the two resulting separated helices. Membrane-bound conformations of alphaS likely mediate the function of the protein, but may also play a role in the aggregation and toxicity of the protein. Here we have undertaken a study of the effects of the three known PD-linked mutations on the detergent- and membrane-bound conformations of alphaS, as well as factors that govern the transition of the protein between the extended helix and broken helix states. Using pulsed dipolar ESR measurements of distances up to 8.7 nm, we show that all three PD-linked alphaS mutants retain the ability to transition from the broken helix to the extended helix conformation. In addition, we find that the ratio of protein to detergent, rather than just the absolute detergent concentration, determines whether the protein adopts the broken or extended helix conformation.
Collapse
Affiliation(s)
- Elka R Georgieva
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | | | | | | | | |
Collapse
|
30
|
Madine J, Hughes E, Doig AJ, Middleton DA. The effects of α-synuclein on phospholipid vesicle integrity: a study using31P NMR and electron microscopy. Mol Membr Biol 2009; 25:518-27. [DOI: 10.1080/09687680802467977] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
31
|
Pandey AP, Haque F, Rochet JC, Hovis JS. Clustering of alpha-synuclein on supported lipid bilayers: role of anionic lipid, protein, and divalent ion concentration. Biophys J 2009; 96:540-51. [PMID: 19167303 DOI: 10.1016/j.bpj.2008.10.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 10/09/2008] [Indexed: 10/21/2022] Open
Abstract
Alpha-synuclein is the major component of Lewy body inclusions found in the brains of patients with Parkinson's disease. Several studies indicate that alpha-synuclein binds to negatively charged phospholipid bilayers. We examined the binding of alpha-synuclein to membranes containing different amounts of negatively charged lipids using supported lipid bilayers, epifluorescence microscopy, fluorescence recovery after photobleaching, and bulk fluorescence techniques. The membranes contained phosphatidylcholine and phosphatidylglycerol. In the absence of protein, these lipids mix uniformly. Our results show that the propensity of alpha-synuclein to cluster on the membrane increases as the concentration of anionic lipid and/or protein increases. Regions on the lipid bilayer where alpha-synuclein is clustered are enriched in phosphatidylglycerol. We also observe divalent metal ions stimulate protein cluster formation, primarily by promoting lipid demixing. The importance of protein structure, lipid demixing, and divalent ions, as well as the physiological implications, will be discussed. Because membrane-bound alpha-synuclein assemblies may play a role in neurotoxicity, it is of interest to determine how membranes can be used to tune the propensity of alpha-synuclein to aggregate.
Collapse
Affiliation(s)
- Anjan P Pandey
- Department of Chemistry, Purdue University, West Lafayette, Indiana, USA
| | | | | | | |
Collapse
|
32
|
Jack ER, Madine J, Lian LY, Middleton DA. Membrane interactions of peptides representing the polybasic regions of three Rho GTPases are sensitive to the distribution of arginine and lysine residues. Mol Membr Biol 2008; 25:14-22. [PMID: 18097952 DOI: 10.1080/09687680701494007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Rho GTPases are a multifunctional family of proteins that are localized at cellular membranes via an isoprenyl group covalently linked to a C-terminal cysteine. Close to this primary site of membrane anchoring there is often found an additional polybasic region (PBR), which plays a secondary role in membrane binding and targeting of the complex. Here, peptides derived from the PBRs of the Rho family proteins Rac1 (K(183)KRKRK), TCL (K(198)KKKKR) and Cdc42 (P(182)KKSRR) were prepared with hexalysine (K(6)) and hexaarginine (R(6)) to study their interactions with multilamellar vesicles of phosphatidylglycerol (DOPG) and headgroup-deuterated dimyristoylphosphatidylcholine (DMPC-d(4)) using (2)H and (31)P NMR. The membranes retained their lamellar architecture after peptide binding, but the (2)H NMR line shapes for DMPC-d(4) indicated that the bound peptides altered the orientation of the choline headgroups, consistent with a change in membrane surface charge. Rac1 and TCL peptides appeared to affect the headgroup orientation similarly to K(6), although the perturbations were weaker and unlike those induced by the Cdc42 peptide and R(6). Magic-angle spinning (31)P NMR spectra of the membranes showed significant and selective broadening of the peak for DMPC after addition of the peptides, with R(6) and the Cdc42 peptide having the greatest effect. The selective broadening may be a consequence of the lipids separating into short-lived domains enriched in peptide-bound DOPG and peptide-free DMPC. These results illustrate that a complex relationship exists between the sequence of PBRs and their behaviour at membrane surfaces, which may have implications for the cellular functions and localization of Rho GTPases.
Collapse
Affiliation(s)
- Edward R Jack
- School of Biological Sciences, University of Liverpool, Liverpool, UK
| | | | | | | |
Collapse
|
33
|
Abstract
Aggregation and fibrillation of alpha-synuclein bound to membranes are believed to be involved in Parkinson's and other neurodegenerative diseases. On SDS micelles, the N-terminus of alpha-synuclein forms two curved helices linked by a short loop. However, its structure on lipid bilayers has not been experimentally resolved. Using MD simulations with an implicit membrane model we show here that, on a planar mixed membrane, the truncated alpha-synuclein (residues 1-95) forms a bent helix. Bending of the helix is not due to the protein sequence or membrane binding, but to collective motions of the long helix. The backbone of the helix is approximately 2.5 A above the membrane surface, with some residues partially inserted in the membrane core. The helix periodicity is 11/3 (11 residues complete three full turns) as opposed to 18/5 periodicity of an ideal alpha-helix, with hydrophobic residues towards the membrane, negatively charged residues towards the solvent and lysines on the polar/nonpolar interface. A series of threonines, which are characteristic for alpha-synuclein and perhaps a phosphorylation site, is also located at the hydrophobic/hydrophilic interface with their side chain often hydrogen bonded to the main-chain atom. The calculations show that the energy penalty for change in periodicity from the 18/5 to 11/3 on the anionic membrane is overcome by favorable solvation energy. The binding of truncated alpha-synuclein to membranes is weak. It prefers anionic membranes but it also binds marginally to a neutral membrane, via its C-terminus. Dimerization of helical monomers on the mixed membrane is energetically favorable. However, it slightly interferes with membrane binding. This might promote lateral diffusion of the protein on the membrane surface and facilitate assembly of oligomers that precede fibrillation.
Collapse
Affiliation(s)
- Maja Mihajlovic
- Department of Chemistry, City College of New York, CUNY, New York, New York 10031, USA
| | | |
Collapse
|
34
|
Beyer K. Mechanistic aspects of Parkinson's disease: alpha-synuclein and the biomembrane. Cell Biochem Biophys 2007; 47:285-99. [PMID: 17652776 DOI: 10.1007/s12013-007-0014-9] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 01/07/2023]
Abstract
AA key feature in Parkinson's disease is the deposition of Lewy bodies. The major protein component of these intracellular deposits is the 140-amino acid protein alpha-synuclein that is widely distributed throughout the brain. alpha-synuclein was identified in presynaptic terminals and in synaptosomal preparations. The protein is remarkable for its structural variability. It is almost unstructured as a monomer in aqueous solution. Self-aggregation leads to a variety of beta-structures, while membrane association may result in the formation of an amphipathic helical structure. The present article strives to give an overview of what is currently known on the interaction of alpha-synuclein with lipid membranes, including synthetic lipid bilayers, membraneous cell fractions, synaptic vesicles and intact cells. Manifestations of a functional relevance of the alpha-synuclein-lipid interaction will be discussed and the potential pathogenicity of oligomeric alpha-synuclein aggregates will be briefly reviewed.
Collapse
Affiliation(s)
- Klaus Beyer
- Laboratory of Alzheimer's and Parkinson's Disease Research, Department of Biochemistry, Ludwig Maximilian University, 80336 Munich, Germany.
| |
Collapse
|
35
|
Schmidt E, Seifert M, Baumeister R. Caenorhabditis elegans as a model system for Parkinson's disease. NEURODEGENER DIS 2007; 4:199-217. [PMID: 17596715 DOI: 10.1159/000101845] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Parkinson's disease (PD) is one of the most common age-related neurodegenerative diseases that is characterized by selective loss of dopaminergic neurons. Despite recent findings from mammalian model systems, molecular mechanisms of the pathophysiology are poorly understood. Given the high conservation of molecular pathways from invertebrates to mammalians, combined with technical advantages, such as high-throughput approaches, Caenorhabditis elegans represents a powerful system for the identification of factors involved in neurodegeneration. In this review we describe that C. elegans can be used to advance our understanding of the genetic mechanisms implicated in these disorders.
Collapse
Affiliation(s)
- Enrico Schmidt
- Bioinformatics and Molecular Genetics (Faculty of Biology), Center for Biochemistry, University of Freiburg, Freiburg, Germany
| | | | | |
Collapse
|
36
|
Kelly BA, Neil SJ, McKnight A, Santos JM, Sinnis P, Jack ER, Middleton DA, Dobson CB. Apolipoprotein E-derived antimicrobial peptide analogues with altered membrane affinity and increased potency and breadth of activity. FEBS J 2007; 274:4511-25. [PMID: 17681018 DOI: 10.1111/j.1742-4658.2007.05981.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Host-derived anti-infective proteins represent an important source of sequences for designing antimicrobial peptides (AMPs). However such sequences are often long and comprise diverse amino acids with uncertain contribution to biological effects. Previously, we identified a simple highly cationic peptide derivative of human apolipoprotein E (apoEdp) that inhibited a range of microorganisms. Here, we have dissected the protein chemistry underlying this activity. We report that basic residues and peptide length of around 18 residues were required for activity; however, the Leu residues can be substituted by several other residues without loss of activity and, when substituted with Phe or Trp, resulted in peptides with increased potency. These apoEdp-derived AMPs (apoE-AMPs) showed no cytotoxicity and minimal haemolytic activity, and were active against HIV and Plasmodium via an extracellular target. CXCR4 and CCR5 strains of HIV were inhibited though an early stage in viral infection upstream of fusion, and a lack of inhibition of vesicular stomatitis virus G protein pseudotyped HIV-1 suggested the anti-HIV activity was relatively selective. Inhibition of Plasmodium invasion of hepatocytes was observed without a direct action on Plasmodium integrity or attachment to cells. The Trp-substituted apoE-AMP adhered to mammalian cells irreversibly, explaining its increased potency; NMR experiments confirmed that the aromatic peptides also showed stronger perturbation of membrane lipids (relative to apoEdp). Our data highlight the contribution of specific amino acids to the activity of apoEdp (and also potentially unrelated AMPs) and suggest that apoE-AMPs may be useful as lead agents for preventing the early stages of HIV and Plasmodium cellular entry.
Collapse
Affiliation(s)
- Bridie A Kelly
- Faculty of Life Sciences, The Mill, The University of Manchester, UK
| | | | | | | | | | | | | | | |
Collapse
|
37
|
Monti B, Polazzi E, Batti L, Crochemore C, Virgili M, Contestabile A. Alpha-synuclein protects cerebellar granule neurons against 6-hydroxydopamine-induced death. J Neurochem 2007; 103:518-30. [PMID: 17635667 DOI: 10.1111/j.1471-4159.2007.04778.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The physiological role of alpha-synuclein, a protein found enriched in intraneuronal deposits characterizing Parkinson's disease, is debated. While its aggregation is usually considered linked to neuropathology, its normal function may be related to fundamental processes of synaptic transmission and plasticity. By using antisense oligonucleotide strategy, we report in this study that alpha-synuclein silencing in cultured cerebellar granule cells results in widespread death of these neurons, thus demonstrating an essential pro-survival role of the protein towards primary neurons. To study alpha-synuclein expression and processing in a Parkinson's disease model of neurotoxicity, we exposed differentiated cultures of cerebellar granule neurons to toxic concentrations of 6-hydroxydopamine (6-OHDA). This resulted in neuronal death accompanied by a decrease of the monomeric form of alpha-synuclein, which was due to both decreased synthesis of the protein and its increased mono-ubiquitination accompanied by nuclear translocation. The essential neuroprotective role of alpha-synuclein was confirmed by the fact that subchronic valproate treatment, which increases alpha-synuclein expression and prevents its nuclear translocation in cerebellar granule cells exposed to 6-OHDA, significantly protected these neurons from 6-OHDA insult. In agreement with the pro-survival role of alpha-synuclein in this model, subtoxic concentrations of alpha-synuclein antisense oligonucleotides, aggravated 6-OHDA toxicity towards granule neurons. Our results demonstrate that normal alpha-synuclein expression is essential for the viability of primary neurons and that its pro-survival role is abolished in 6-OHDA neurotoxic challenge. These results are relevant to more precisely define the role of alpha-synuclein in neuronal cells and to better understand its putative involvement in neurodegeneration.
Collapse
Affiliation(s)
- Barbara Monti
- Department of Biology, University of Bologna, Bologna, Italy
| | | | | | | | | | | |
Collapse
|
38
|
Abstract
Aggregation of alpha-synuclein, an abundant and conserved pre-synaptic brain protein, is implicated as a critical factor in several neurodegenerative diseases. These diseases, known as synucleinopathies, include Parkinson's disease, dementia with Lewy bodies (LBs), diffuse LB disease, the LB variant of Alzheimer's disease, multiple system atrophy, and neurodegeneration with brain iron accumulation type I. Although the precise nature of in vivoalpha-synuclein function remains elusive, considerable knowledge has been accumulated about its structural properties and conformational behavior. alpha-Synuclein is a typical natively unfolded protein. It is characterized by the lack of rigid, well-defined, 3-D structure and possesses remarkable conformational plasticity. The structure of this protein depends dramatically on its environment and it accommodates a number of unrelated conformations. This paper provides an overview of the biochemistry, biophysics, and neuropathology of alpha-synuclein aggregation.
Collapse
Affiliation(s)
- Vladimir N Uversky
- Department of Biochemistry and Molecular Biology, Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana, USA.
| |
Collapse
|