Talk abstracts
Talk on Thursday 04:45-05:00pm submitted by Mia Ashriem
LRRK2-mediated vesicle exocytosis: A novel response to lysosomal damage in Parkinsons disease
Mia Ashriem (MCDB), Nuria Fernandez (Department of Neurology, The Neuroscience Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA.), Tsion Tegicho (Department of Neurology, The Neuroscience Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA.), Luis Bonet-Ponce
Abstract:
Parkinsons disease (PD) is characterized by dopaminergic neurodegeneration and intracellular protein aggregates. Lysosomal dysfunction is a hallmark of PD, with mutations in LRRK2, the most prevalent PD familial gene, linked to defects in the endolysosomal system. However, the precise cellular role of LRRK2 remains unclear. In previous work, we identified a novel lysosomal process termed Lysosomal Tubulation/Sorting driven by LRRK2 (LYTL). During LYTL, LRRK2 is recruited to damaged lysosomes, where it phosphorylates specific RAB GTPases, promoting the recruitment of effector proteins such as JIP4 and RILPL1. This drives the formation of dynamic membrane tubules that generate motile vesicles. However, the destination and cargo of these vesicles remain unknown.
Here, we used RILPL1 as a marker to track LYTL vesicles following lysosomal damage. Our data show that these vesicles traffic both within the cytoplasm and to the plasma membrane (PM). Using total internal reflection fluorescence microscopy, we detected RILPL1-positive vesicles at the PM. Their presence at the membrane was abolished by LRRK2 kinase inhibition, confirming their LRRK2 dependence. PM pull down assays revealed the presence of LYTL vesicles markers but not LRRK2. Quantitative analysis revealed preferential accumulation of RILPL1-positive vesicles at the PM compared to the cytosol. Furthermore, using the cell-impermeable dye Cy5 to detect fusion events, we observed frequent colocalization with RILPL1-positive vesicles, providing direct evidence of exocytosis. Together, these findings identify the PM as a primary destination for LYTL vesicles and provide the first mechanistic evidence for LRRK2-mediated vesicle exocytosis following lysosomal damage. Ongoing studies aim to define LYTL vesicle cargo using proteomics and to identify the molecular machinery governing vesicle fusion, providing further insight into LYTLs role in lysosomal damage responses and its potential contribution to PD pathogenesis.
Keywords: Lysosome, vesicle trafficking, Parkinsons disease