Parkinson’s disease (PD) is a common neurodegenerative disorder characterized by motor and non-motor symptoms. The main features are the degeneration of dopaminergic neurons in the substantia nigra pars compacta and the presence of neuronal intracytoplasmic inclusions, known as Lewy Bodies. One of the major components of Lewy Bodies are α-Synuclein (α-Syn) fibrillar aggregates. α-Syn is an intrinsically disordered protein (IDP) of 140 amino acids. It is a presynaptic protein expressed in the nervous system and encoded by the gene SNCA. The most common mutations of the protein reside in the N-terminal domain and may alter the fibrillation process. In the mutant E46K, the negatively charged glutamic acid in position 46 is substituted by a positively charged lysine leading to a large increase in β-sheet structure formation with respect to the WT. The drugs currently in use act on the symptoms of PD but new therapeutic approaches aimed at preventing or curing the disease are under investigation. Targeting α-Syn at various stages of its synthesis and action is of great interest. For this purpose, plant polyphenols and catechols of natural and synthetic origin showed to be promising in interfering with α-Syn aggregation process. Indeed, many polyphenols beside having antioxidant properties and being able to scavenge free radicals and ROS, manifested their ability to inhibit the formation of amyloid fibrils involved in the development of PD. The data available on Oleuropein Aglycone (OleA), its derivatives and other natural molecules suggest the possibility of exploiting the anti-amyloidogenic properties of these compounds for the development of new therapeutic strategies against this neurodegenerative disease. The purpose of this project was to study the metabolite’s extracts of three Antarctica fungal species: T. versicolor, L. betulina and S. brinkmannii. These fungi are not yet characterized and may be the source of new polyphenol compounds. Therefore, the use of biochemical and biophysical techniques allowed to investigate the effects of the different fungal extracts on the aggregation pathway of E46K mutant. To overcome the lack of information on the mechanism of action and specificity of these polyphenolic compounds; part of this project was dedicated to elucidating the mechanism by which a polyphenolic aggregation inhibitor interacts with α-Syn. These studies were conducted using a in silico approach based on molecular dynamics (MD). In conclusion, it has been demonstrated that the fungal extracts contain substances able to influence the aggregative pathway of α-Syn. The bioinformatics’ analysis confirmed that the covalent interaction of a DOPET-derived compound causes a general alteration of the protein stability. The results obtained must be supported by further analysis directed to improving the knowledge on the metabolites contained in the fungal extracts and on the mechanism of action of the aggregation inhibitors.
La malattia di Parkinson (PD) è una comune patologia neurodegenerativa caratterizzata da sintomi di tipo motorio e non motorio. I segni tipici di questo morbo sono la degenerazione dei neuroni dopaminergici a livello della substantia nigra pars compacta e la presenza di inclusioni citoplasmatiche note come corpi di Lewy (LB). Tra i componenti dei corpi di Lewy ci sono aggregati fibrillari di α-Sinucleina (α-Syn). α-Syn è una proteina intrinsecamente disordinata composta da 140 amino acidi. È una proteina presinaptica espressa nel sistema nervoso e codificata dal gene SNCA. Le sue mutazioni più comuni hanno luogo nel dominio N-terminale e possono alterare il processo di fibrillazione. Nel mutante E46K, la sostituzione dell’acido glutammico con carica negativa in posizione 46 con la lisina carica positivamente causa un aumento nella formazione di struttura β rispetto al WT. I farmaci attualmente in uso agiscono solo sui sintomi del PD, ma è in corsa la ricerca di nuovi approcci terapeutici che mirano a prevenire o curare la malattia. Agire su α-Syn nella sua fase di sintesi o azione è di particolare interesse. A questo scopo, polifenoli di origine naturale e sintetica si sono dimostrati promettenti modulatori del processo aggregativo di α-Syn. Infatti, molti polifenoli oltre ad avere proprietà antiossidanti e legare i radicali liberi, hanno la capacità di inibire la formazione delle fibrille amiloidi coinvolte nello sviluppo della malattia di Parkinson. I dati disponibili su Oleuropeina Aglicone (OleA), i suoi derivati e altre molecole di origine naturale suggeriscono la possibilità di sfruttare le proprietà anti-amiloidogeniche di questi composti per lo sviluppo di nuovi farmaci contro questo disturbo neurodegenerativo. L’obiettivo di questo progetto è studiare gli estratti metabolici di tre specie di funghi antartici: T. versicolor, L. betulina and S. brinkmannii. Questi funghi non sono ancora stati caratterizzati e potrebbero essere fonte di nuovi polifenoli. Perciò, attraverso tecniche biochimiche e biofisiche sono stati analizzati gli effetti dei diversi estratti fungini sul processo di aggregazione del mutante E46K. Per superare la mancanza di informazioni sul meccanismo d’azione e la specificità di questi composti polifenolici, parte di questo progetto è stata dedicata a delucidare il meccanismo attraverso cui gli inibitori di aggregazione di natura polifenolica interagiscono con α-Syn. Questi studi sono stati condotti utilizzando un approccio in silico basato sulle dinamiche molecolari (MD). In conclusione, è stato dimostrato che gli estratti fungini contengono sostanze capaci di influenzare il processo aggregativo di α-Syn. Le analisi bioinformatiche hanno confermato che l’interazione covalente di un composto derivato da DOPET causa una alterazione generale della stabilità della proteina. I risultati ottenuti necessitano di essere supportati da ulteriori analisi, al fine di migliorare la conoscenza sui metaboliti presenti negli estratti di funghi antartici e sul meccanismo d’azione degli inibitori di aggregazione di α-Syn.
Targeting α-synuclein as possible approach to combat Parkinson's disease
INCIARDI, ILENIA
2021/2022
Abstract
Parkinson’s disease (PD) is a common neurodegenerative disorder characterized by motor and non-motor symptoms. The main features are the degeneration of dopaminergic neurons in the substantia nigra pars compacta and the presence of neuronal intracytoplasmic inclusions, known as Lewy Bodies. One of the major components of Lewy Bodies are α-Synuclein (α-Syn) fibrillar aggregates. α-Syn is an intrinsically disordered protein (IDP) of 140 amino acids. It is a presynaptic protein expressed in the nervous system and encoded by the gene SNCA. The most common mutations of the protein reside in the N-terminal domain and may alter the fibrillation process. In the mutant E46K, the negatively charged glutamic acid in position 46 is substituted by a positively charged lysine leading to a large increase in β-sheet structure formation with respect to the WT. The drugs currently in use act on the symptoms of PD but new therapeutic approaches aimed at preventing or curing the disease are under investigation. Targeting α-Syn at various stages of its synthesis and action is of great interest. For this purpose, plant polyphenols and catechols of natural and synthetic origin showed to be promising in interfering with α-Syn aggregation process. Indeed, many polyphenols beside having antioxidant properties and being able to scavenge free radicals and ROS, manifested their ability to inhibit the formation of amyloid fibrils involved in the development of PD. The data available on Oleuropein Aglycone (OleA), its derivatives and other natural molecules suggest the possibility of exploiting the anti-amyloidogenic properties of these compounds for the development of new therapeutic strategies against this neurodegenerative disease. The purpose of this project was to study the metabolite’s extracts of three Antarctica fungal species: T. versicolor, L. betulina and S. brinkmannii. These fungi are not yet characterized and may be the source of new polyphenol compounds. Therefore, the use of biochemical and biophysical techniques allowed to investigate the effects of the different fungal extracts on the aggregation pathway of E46K mutant. To overcome the lack of information on the mechanism of action and specificity of these polyphenolic compounds; part of this project was dedicated to elucidating the mechanism by which a polyphenolic aggregation inhibitor interacts with α-Syn. These studies were conducted using a in silico approach based on molecular dynamics (MD). In conclusion, it has been demonstrated that the fungal extracts contain substances able to influence the aggregative pathway of α-Syn. The bioinformatics’ analysis confirmed that the covalent interaction of a DOPET-derived compound causes a general alteration of the protein stability. The results obtained must be supported by further analysis directed to improving the knowledge on the metabolites contained in the fungal extracts and on the mechanism of action of the aggregation inhibitors.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/35922