Unraveling the role of VPS13C in lysosomal homeostasis and interorganellar homeostasis using new cellular and in vivo models.

Dementia is one of the main afflictions of today’s society, with Dementia with Lewy Bodies (DLB) representing around 25% of all dementias, only second to Alzheimer’s Disease. DLB, together with Parkinson’s Disease (PD), comprise Lewy Body Diseases (LBD), a group of disorders characterized by the presence of Lewy bodies in the brain. However, the cause for the formation of Lewy bodies, as well as their exact role on the pathogenesis of LBD, is still unclear. Recently, mutations on the vacuolar protein sorting 13 homolog C (VPS13C) gene have been found on patients diagnosed with PD and DLB, highlighting this gene as a new crucial player in LBD. VPS13C localizes to late endosome/lysosome (LE/Lys)-endoplasmic reticulum (ER) and LE/Lys-lipid droplet (LD) contact sites where it likely functions in transferring lipids. As such, VPS13C is functionally involved in maintaining proper membrane homeostasis and interorganellar communication. For the past two years, the lab has developed a series of tools, including new VPS13C antibodies as well as KO and rescued cell lines, that are paving the way to uncovering VPS13C functions in lipid metabolism and lysosomal function. In this PhD, we focus will be on the use of iPSCs and in-vivo models to validate the data obtained on immortalized cell lines. iPSCs derived from patients lymphocytes carrying VPS13C mutations are already available in house. Firstly, CRISPR/Cas9 genome editing will be used to generate isogenic controls as well as VPS13C KO iPSCs. From thereon, neuronal progenitor cells will be derived that will serve as the basis to obtain human differentiated neurons. Through a collaboration with Prof. Baekelandt (KU Leuven), we have access to mouse and rat α-synuclein pathology models. Using short hairpin RNA, VPS13C will be knocked down in these models, while viral vectors encoding VPS13C mutants will be co-injected together with α-synuclein. Both cellular and in vivo models will be used to study the impact of VP13C dysfunction on endolysosomal transport regulation and interorganellar communication. This knowledge is needed to understand how VPS13C dysfunction leads to DLB/PD pathology including α-synuclein aggregation ultimately resulting in neuronal cell death in in-vivo models.