Modulating Alzheimer's Disease by mTORC1 inhibition to augment lysosomal activity

PROJECT SUMMARY/ABSTRACT: This proposal is in application for a Pathway to Independence Award for Dr. Travis Lear at the Aging Institute at the University of Pittsburgh. Dr. Lear has extensive experience in the molecular biology of ubiquitination in aging, inflammation, autophagy, and lysosome biology. This K99/R00 would be a crucial step for Dr. Lear as part of his career goal of reaching research independence. The focus of Dr. Lear’s future lab will be to study the mechanisms of protein degradation and lysosomal activity in neurodegeneration in pursuit of uncovering new therapeutic avenues. Under this K99/R00 award, Dr. Lear would have protected time for additional training in neurobiology techniques and aging biology, and for career development to facilitate a successful transition to research independence. This mentorship team of experts in aging, lysosomal, and neurobiology combined with the scientific environment at the Aging Institute will be ideal for Dr. Lear’s training. The scientific expertise training will entail 1) in vitro primary tissue culture skill, 2) study of iPSC development, differentiation, and gene-editing, 3) generation and phenotypic characterization of mouse models of neurodegeneration. Dr. Lear’s leadership training will focus on 1) integration to scientific community through networking, 2) enhancing his mentoring skills, 3) improving grantsmanship. Successful completion of the proposed research and training plan will provide the knowledge and experience necessary to progress toward Dr. Lear’s career goal of becoming an independent investigator studying neuronal aging and Alzheimer’s Disease (AD). To accomplish this, Dr. Lear proposes to study a new mechanism of proteolytic control of lysosomal activation to augment processing of pathogenic tau protein aggregates in models of AD. Specifically, Dr. Lear has elaborated a model in which a key mTORC1 inhibitor protein, KPTN, is potently controlled by the E3 ubiquitin ligase PDZRN3, which ubiquitinates and fates KPTN for degradation. Also, unbiased screening yielded a small molecule KPTN activator which increases KPTN protein level, inhibits mTORC1 activity, and increases lysosomal number and activity. Excitingly, pharmacological augmentation of KPTN reduces tau protein aggregation in vitro, which has therapeutic implications for the treatment of Alzheimer’s Disease. The net effect of KPTN augmentation would therefore aid in clearance of toxic protein aggregates by activation of autophagy. This leads to the central hypothesis that PDZRN3 control of KPTN affects neuronal lysosomal activity and that genetic or pharmacological activation of KPTN may be an avenue to reduce tau protein aggregates. Two aims will interrogate this hypothesis: (1) To examine the mechanism and biologic effect of the PDZRN3-KPTN axis on tau-aggregation in vitro with inducible pluripotent stem cell (iPSC) and primary cell models, and (2) to examine this mechanism and effect using genetic and pharmacological approaches in animal models of tau spreading. Dr. Lear will also pursue a structured training plan including formal course work, conferences, and hands-on training of new techniques, under the guidance of primary mentor Dr. Toren Finkel, and co-mentors Dr. Stacey Rizzo and Dr. Bill Chen.