Oxidative and nitrative alpha‐synuclein modifications and proteostatic stress: implications for disease mechanisms and interventions in synucleinopathies |
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| Authors: | Stefan Schildknecht Hanne R. Gerding Christiaan Karreman Malte Drescher Hilal A. Lashuel Tiago F. Outeiro Donato A. Di Monte Marcel Leist |
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| Affiliation: | 1. Department of Biology, Doerenkamp‐Zbinden Chair for In vitro Toxicology and Biomedicine, University of Konstanz, , Konstanz, Germany;2. Department of Chemistry, Konstanz Research School Chemical Biology and Zukunftskolleg, University of Konstanz, , Konstanz, Germany;3. Laboratory of Molecular and Chemical Biology of Neurodegeneration, Ecole Polytechnique Federale, , Lausanne, Switzerland;4. Department of Neurodegeneration and Restorative Research, University Medical Center G?ttingen, , G?ttingen, Germany;5. German Center for Neurodegenerative Diseases (DZNE), , Bonn, Germany |
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| Abstract: | Alpha‐synuclein (ASYN) is a major constituent of the typical protein aggregates observed in several neurodegenerative diseases that are collectively referred to as synucleinopathies. A causal involvement of ASYN in the initiation and progression of neurological diseases is suggested by observations indicating that single‐point (e.g., A30P, A53T) or multiplication mutations of the gene encoding for ASYN cause early onset forms of Parkinson's disease (PD). The relative regional specificity of ASYN pathology is still a riddle that cannot be simply explained by its expression pattern. Also, transgenic over‐expression of ASYN in mice does not recapitulate the typical dopaminergic neuronal death observed in PD. Thus, additional factors must contribute to ASYN‐related toxicity. For instance, synucleinopathies are usually associated with inflammation and elevated levels of oxidative stress in affected brain areas. In turn, these conditions favor oxidative modifications of ASYN. Among these modifications, nitration of tyrosine residues, formation of covalent ASYN dimers, as well as methionine sulfoxidations are prominent examples that are observed in post‐mortem PD brain sections. Oxidative modifications can affect ASYN aggregation, as well as its binding to biological membranes. This would affect neurotransmitter recycling, mitochondrial function and dynamics (fission/fusion), ASYN's degradation within a cell and, possibly, the transfer of modified ASYN to adjacent cells. Here, we propose a model on how covalent modifications of ASYN link energy stress, altered proteostasis, and oxidative stress, three major pathogenic processes involved in PD progression. Moreover, we hypothesize that ASYN may act physiologically as a catalytically regenerated scavenger of oxidants in healthy cells, thus performing an important protective role prior to the onset of disease or during aging. |
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| Keywords: | aggregation alpha‐synuclein dopamine nitric oxide parkinson's disease peroxynitrite |
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