Parkinson's Disease (PD), the second most frequent neurodegenerative disease is characterized by a loss of dopaminergic (DA) neurons in the substantia nigra (SN) and the formation of Lewy bodies containing α-synuclein (α-syn). Nowadays, the pathogenic mechanisms underlying PD are still misunderstood. They may involve a complex interaction between environmental and genetic factors. Among genetic factors, mutations of the α-syn gene such as the A53T mutation can accelerate its aggregation. Another gene involved is the one encoding Leucine-Rich Repeat Kinase 2 (LRRK2). Its G2019S mutation is the most frequent one leading to PD familial forms. Moreover, it has been suggested that α-syn and LRRK2 can act jointly in PD pathogenesis. This idea is supported by one of our previous in vivo study, using AAV as expression vectors, which has shown that LRRK2-G2019S potentiates the dopaminergic cell death induced by α-syn-A53T in the SN of rats. Furthermore, our team recently showed that LRRK2-G2019S induces a significant increase in the number of neurons expressing a pathological form of α-syn (phospho-Ser129) without inducing any cell loss in vitro. Thus, the aim of our project is to determine how α-syn and LRRK2 act together on neuronal stress. We particularly focus on autophagy since this process has been described to be altered in PD, and individually α-syn and LRRK2 have both been found to modulate autophagy. We use a model of rat primary neuronal culture infected with lentiviral to express the WT or mutant forms of α-syn and LRRK2. To induce autophagy in these cultures, we starve them in EBSS. We analyze the basal and induced-autophagic flux by treating them with BafilomycinA1. Analyzes are subsequently done by western blot (conversion of LC3-I to autophagosome-associated LC3-II and p62 expression) and immunofluorescence (expression and localization of LC3 and p62). We showed that α-syn can block neuronal basal autophagy flux. Now, we have to determine if LRRK2 modulate this blockade and what happens for the induced-autophagy flux. In conclusion, our objective is to find which autophagic step is impacted by α-syn and LRRK2 to identify new molecular targets and thereafter develop new therapeutic strategies for PD.