ASSESSING THE PATHOGENESIS OF MULTIPLE SYSTEM ATROPHY THROUGH CELLULAR MODELS

Multiple System Atrophy (MSA) is a severe adult-onset neurodegenerative disease, with an incidence of 0.6 per 100000 persons/year and a survival rate of 6-9 years from the onset. MSA is clinically characterized by parkinsonism, cerebellar ataxia, dysautonomia and pyramidal signs. Two subtypes of the disease can be distinguished, MSA-P and MSA-C, on the basis of the predominant symptomatology, parkinsonian or cerebellar respectively. From a neuropathological point of view, MSA is classified as an alpha-synucleinopathy. However, differently from Parkinson’s disease and Dementia with Lewy bodies, the main intracellular localization of alpha-synuclein aggregates in MSA is not the neuron, but the oligodendrocyte. An effective therapy is not available yet. The pathogenesis of the disease is almost completely unknown and the available models, mainly transgenic animals overexpressing human alpha-synuclein under the promoter of genes specifically expressed in oligodendrocytes, do not fully recapitulate the pathogenic mechanisms. The aim of the present project was the generation and study of new experimental models for the identification of the molecular mechanisms of the disease and new therapeutic targets. The study has taken advantage from the use of peripheral blood cells, fibroblasts’ primary cultures, iPSC-derived dopaminergic neurons and brain tissue and has focused on several topics, including autophagy, mitochondrial functioning and alpha-synuclein expression. The main findings in patients have been: an increase of mtDNA amount in peripheral blood cells and in brain tissue, selectively in the cerebellar subtype; an impairment of mitochondrial respiratory chain activity in fibroblasts and iPSC-derived neurons; an increase of mitochondrial mass and of complex II amount, an increased expression of mitochondria-related genes, an increase of the amount of many enzymes involved in the synthesis of Coenzyme Q10 in neurons; an impairment of the autophagic pathway in neurons; a reduced expression of neuronal markers in advanced stages of dopaminergic differentiation; hypomethylation of a CpG island located in alpha-synuclein intron 1. The generation and characterization of the iPSC-derived neuronal model is particularly remarkable because it represents the first comprehensive model of MSA based on this technique. In conclusion, this project has led to the identification of several defects in MSA cells and tissues, suggesting the impairment of specific molecular pathways and contributing to the understanding of the underlying pathogenic mechanisms. Furthermore, this study lays the foundations for several lines of investigation and the proposed model can also have remarkable therapeutic implications for the assessment of effectiveness and tolerability of new pharmacological compounds.