Increased lysosome exocytosis in SH-SY5Y cells overexpressing the P5-ATPase ATP13A2

MARIELA S. FERREIRA-GOMES; HUGO PEDRO ADAMO; DÉBORA E. RINALDI; LUCIANA R. MAZZITELLI; ALEJANDRA LUCÍA MARCOS; GERARDO R. CORRADI; FELICITAS DE TEZANOS PINTO

Congreso; Reunión anual de sociedades de Biociencias; 2019

SAIC

The P-type ion pumps are membrane transporters energized by ATP-hydrolysis which are classified into five subfamilies termed P1-P5. The substrate transported by P5-ATPases is still unknown. ATP13A1-ATP13A5 genes that belong to this group have been identified in humans. Mutations of the ATP13A2 gene were associated with neurodegenerative diseases like Parkinson?s Disease, Neuronal Ceroid Llipofuscinosis (CNL12), hereditary spastic paraplegia (SPG78) and amyotrophic lateral sclerosis. ATP13A2 is localized in lysosomes and late endosomes. Dysfunction of this protein diminishes the lysosomal degradation, the autophagic flux and the exosome externalization. Lysosomal exocytosis (Ly-exocytosis) is now arising as a potential therapeutic target in diseases characterized by the accumulation of undigested material. We have shown that ATP13A2 expression modifies the lipid homeostasis in a way that seems to switch the endo-lysosomal system towards endo-lysosome secretion. By measuring the activity of the lysosomal enzyme -hexosaminidase in the culture medium, we found that SH-SY5Y cells stably expressing the ATP13A2 (SH-SY5Y-ATP13A2) have an increased Ly-exocytosis. As this process is upregulated by increasing lysosomal Ca2+ levels, we evaluated the Ca2+ kinetics by following the fluorimetric measurement of the calcium sensor Fura-2 AM in preloaded SH-SY5Y cells. We found that SH-SY5Y-ATP13A2 cells are able to diminish the cytoplasmic calcium content more efficiently than control cells overexpressing an inactive ATP13A2 pump. Considering that Ly-exocytosis is dependent upon cytoskeleton dynamic, we evaluated the cytoskeleton structure by fluorescence microscopy. Preliminary results show that SH-SY5Y-ATP13A2 have a more prominent cortical actin cytoskeleton distribution than control cells. Altogether these results suggest that ATP13A2 overexpression may be favoring Ly-exocytosis in SH-SY5Y cells.