Project Summary Neurodegenerative diseases, especially Alzheimer’s Disease (AD) and Parkinson’s Disease (PD), affect millions of people globally and represent a US major healthcare burden. AD is the world’s most common cause of dementia, and is the sixth leading cause of death in the US. PD is motor disabling condition that advances to cognitive deficits. Currently there exist no effective therapies for AD or PD; even some of the drugs used to ameliorate symptoms, such as in PD, cause serious long-term side effects that may be worse than the disease itself. In AD and PD, accumulation of Amyloid-β (Aβ) or α-Synuclein (α-Syn) and their subsequent aggregation, cause neuronal toxicity, including neuroinflammation, synaptic deficits and neurodegeneration, leading to cognitive or motor deficits. In this application, we conceive an innovative genetic tool (named Autophagon, or AFN) to be developed as a gene therapy that helps target toxic Aβ or α-Syn species to autophagy, an important degradative pathway that is usually impaired in AD and PD. AFN will feature a synthetic gene fragment to help sequester Aβ or α-Syn aggregates and deliver them to the autophagic vesicles for clearance from the neurons. Using viral vectors, we will deliver AFN to cells or to mouse brain via specific stereotaxic injections. First, we will test AFN in vitro using 2D and 3D (brain organoid) neuronal cultures derived from iPSCs harboring APP/PSEN1 or α-Syn mutations that drive Aβ or α-Syn aggregation, respectively, and assess the ability of AFN to suppress aggregate formation and neuronal toxicity. Second, we will use mouse models of AD (with a genetic knock-in of human APP mutations that cause Aβ aggregation) and PD (expressing aggregation-prone mutant human α-Syn) to test the therapeutic potential of AFN and its ability to prevent aggregate formation, neurodegeneration, and cognitive or motor deficits in vivo. If successful, the proposed project will have a major impact on the neurodegenerative diseases field, by developing an effective potential gene therapy for AD and PD, and set the foundation for the next steps of preclinical and clinical testing of this suggested therapy. It may also provide a proof-of-concept for therapy development for other neurodegenerative disorders associated with protein aggregation.