Effect of small molecule activator of autophagy on insulin signaling, senescence, and neuropathology in mouse models of Alzheimer's disease - PROJECT SUMMARY Although Aduhelm and Leqembi were recently approved for treating Alzheimer's disease (AD) patients, the reversibility and long-term benefits to patients remain far from reality. Accumulating data suggest that insulin resistance and markers of senescence increase during normal aging and even more so in AD as reflected by colocalization of neurofibrillary tangles (NFTs) and senescence markers in the neurons of both AD patients and mouse models of AD. Also, the impaired autophagy-lysosome pathway (ALP) is known to accelerate senescence, and restoring ALP has been shown to reverse senescence. Therefore, ALP activators are predicted to be excellent drugs to ameliorate multiple pathologies of AD including senescence. Our recently published data suggest that TFEB, a master regulator of ALP, protein levels are reduced in AD brains, TFEB expression by genetic approach reduces lipofuscin, increases lysosome and mitochondria biogenesis, and improves cognition. Considering the enormous potential for TFEB activators, we developed a high-content screening assay and identified TPI-132 as a potent activator of TFEB and ALP. TPI-132 dose- dependently dephosphorylated TFEB, has relatively low toxicity, and rescues doxorubicin- and d-galactose- induced senescence in cell lines and primary neurons. However, TPI-132 has low brain penetration. We also found mTOR-independent and calcineurin-dependent mechanism of TPI-132 to dephosphorylate and activate TFEB. Interestingly, we found that TPI-132 administration in old 3xTg mouse model of AD rescued age- associated insulin resistance dose-dependently. More importantly, TPI-132 increased ADAM10/sAPPα levels in the mouse brain following chronic administration. Based on these data, we hypothesize that by modulating TFEB and autophagy activity, TPI-132 increases neuroprotection, mitigates insulin resistance and senescence thereby improving Alzheimer's pathology and cognition. Aim 1 is designed to hit to lead optimization to increase potency and brain permeability, by synthesizing six sets of new compounds with structural diversity. Two best compounds with increased TFEB activity, reduced toxicity, and improved brain penetration and solubility will be selected to test in Aim 2. In aim 2, the selected two analogs will be tested in primary neurons from AD mouse models and iPSC-derived neurons from AD patients on senescence, dendritic spines, and Aβ/tau pathology. In aim 3, TPI-132 and the two best analogs will be administered to 3xTg and PS19 mouse models of AD by i.p. injections at 2 ages, 11 and 17 months for one month. The compounds' effect on insulin tolerance, senescence, synapses, protein aggregates and ALP activity will be quantified and correlated with cognition and compound levels in the brain. TPI-132 is more promising than other reported TFEB activators because besides anti-senescence effects, it increases two powerful neuroprotective factors, ADAM10/sAPPα and thus can be further developed and tested in clinical trials in future studies as new class of drugs for AD.
