Project Grant F31AG104756

AUTOPHAGY LYSOSOME PATHWAY DYSFUNCTION IN NEURONS AND MICROGLIA IN 4R TAUOPATHIES - PROJECT SUMMARY 4R TAUOPATHIES ARE A CLASS OF NEURODEGENERATIVE DISEASES INCLUDING FRONTOTEMPORAL DEMENTIA, PROGRESSIVE SUPRANUCLEAR PALSY, AND CORTICOBASAL DEGENERATION WHICH ARE CHARACTERIZED BY NEURONAL DEATH, MICROGLIOSIS, AND AGGREGATION OF TAU PROTEIN ISOFORMS CONTAINING FOUR MICROTUBULE BINDING REPEATS (4R). 4R TAUOPATHIES ARE ASSOCIATED WITH INCREASED EXPRESSION OF THE 4R TAU ISOFORM (ENCODED BY THE MAPT GENE) RELATIVE TO THE 3R TAU ISOFORM, WHICH CAN OCCUR EITHER SPORADICALLY OR THROUGH SPLICING MUTATIONS SUCH AS MAPT IVS10+16. CURRENTLY, THE CELL AUTONOMOUS IMPACTS OF INCREASED 4R TAU IN NEURONS AND MICROGLIA AND SUBSEQUENT CONTRIBUTIONS TO PATHOLOGY REMAIN A CRITICAL KNOWLEDGE GAP, POSING A CRUCIAL OBSTACLE TO DEVELOPING EFFECTIVE TREATMENTS. NEURONS AND MICROGLIA RELY ON A FINELY TUNED AND FUNCTIONAL AUTOPHAGY LYSOSOME PATHWAY TO DELIVER MATERIAL TO THE LYSOSOME FOR DEGRADATION AND TO MAINTAIN A HEALTHY PROTEOME. THE GOAL OF THIS PROPOSAL IS TO DETERMINE WHETHER 4R TAU IS SUFFICIENT TO DISRUPT THE AUTOPHAGY LYSOSOME PATHWAY IN A MANNER THAT CONTRIBUTES TO DISEASE PATHOPHYSIOLOGY. THE CENTRAL HYPOTHESIS IS THAT 4R TAU IS SUFFICIENT TO DISRUPT THE AUTOPHAGY LYSOSOME PATHWAY IN NEURONS AND MICROGLIA IN A CELL-TYPE SPECIFIC MANNER AND THAT COMPOUNDS WHICH TARGET THIS PATHWAY CAN RESCUE TAU DEGRADATION. TO TEST THIS, THE WORK PROPOSED HERE WILL HARNESS INDUCED PLURIPOTENT STEM CELL (IPSC) TECHNOLOGY TO EVALUATE THE IMPACT OF MANIPULATING 4R TAU EXPRESSION USING GENETIC (PATIENT-DERIVED MAPT IVS10+16 IPSCS AND ISOGENIC MAPT WT CONTROLS) AND PHARMACOLOGIC (ANTISENSE OLIGONUCLEOTIDES THAT SHIFT MAPT SPLICING TOWARDS 4R (4R-ASO)) APPROACHES. AIMS 1 AND 2 WILL DETERMINE WHETHER INCREASED 4R TAU IS SUFFICIENT TO IMPAR THE AUTOPHAGY LYSOSOME PATHWAY AND TAU DEGRADATION CELL AUTONOMOUSLY IN IPSC-DERIVED NEURONS AND MICROGLIA, RESPECTIVELY. AIM 3 WILL EXAMINE THE THERAPEUTIC POTENTIAL OF COMPOUNDS WHICH TARGET THE AUTOPHAGY LYSOSOME PATHWAY IN NEURON-MICROGLIA CO- CULTURES. THE INVESTIGATOR, KYLIE SCHACHE, WILL GAIN ADVANCED TRAINING IN AUTOPHAGY, MICROGLIA BIOLOGY, STEM CELL MODELS, AND LIGHT MICROSCOPY IN SUPPORT OF THIS INNOVATIVE WORK. THE MENTORS SELECTED FOR THIS TRAINING, DR. CELESTE KARCH AND DR. DAVID KAST, PROVIDE COMPLEMENTARY EXPERTISE IN THESE TRAINING DOMAINS. COMPLETION OF THIS RESEARCH AND MENTORED TRAINING PLAN WILL REVEAL NOVEL MECHANISTIC INSIGHTS AND THERAPEUTIC APPROACHES FOR 4R TAUOPATHIES AND ESTABLISH A FOUNDATION FOR A CAREER AS AN INDEPENDENT RESEARCHER.