This study aims to elucidate the mechanisms underlying Parkinson's disease (PD) by analyzing the effects of abnormalities in prosaposin (PSAP) and progranulin (PGRN) on the localization and activity of glucocerebrosidase (GCase), a lysosomal enzyme implicated in PD pathology. Using cell and mouse models, we will identify how changes in the functional network of PSAP and PGRN trigger PD pathology. Furthermore, we will explore compounds that can ameliorate these abnormalities and develop novel disease-modifying therapies for PD based on the findings.