Alzheimer?s disease (AD) is an irreversible and progressive neurodegenerative disorder that currently affects an estimated 5.7 million individuals in the USA. This age onset disorder affects elderly individuals disproportionately. It is estimated that by 2050, the number of AD patients in the US will increase to ~14 million. In the absence of effective therapeutic interventions that can prevent or reverse AD pathologies, the disease is likely to impose a significant economic burden, estimated to be $234 billion (in addition to the $259 billion spent in the medical care of AD patients). Therefore, there is a dire need to identify pharmacologic agents that can prevent/reverse/slow-down AD progression. Recent advances in our understandings of Tau biology suggest that liquid-liquid phase separation (LLPS) plays crucial roles in both Tau physiology and pathology. For example, LLPS of Tau aids microtubule assembly and/or stabilizes pre-formed microtubule bundles (physiologic role of Tau LLPS). On the other hand, Tau condensates can initiate pathologic protein aggregation (role of LLPS in Tau pathology). Based on these observations and our preliminary data, here, we propose to develop and implement a screening pipeline that selectively targets pathologic liquid-to-solid transformation of Tau. For our screening program, we will employ state-of-the-art optical tweezer-based condensate fusion assay that provides a label- free method for characterizing condensate material state(s).
In Aim 1, we will identify pharmacologic compounds that prevent Tau condensate-derived protein aggregation without altering (or minimally perturbing) Tau?s physiologic condensation.
In Aim 2, we will validate these compounds? effectiveness using biochemical and cell biology methods. We posit that our proposed approach will be broadly applicable to many other physiologic protein condensates whose aggregations are linked to degenerative disorders.
Self-association of Tau is intricately associated with both Tau?s physiology (condensate-mediated microtubule assembly and/or stabilization) and pathology (condensate-derived protein aggregation). Here, we propose to develop a screening method that allows selective targeting of Tau aggregation without interfering with the protein?s physiologic condensation. We postulate that this screening method can be easily applied to other protein systems that undergo pathologic aggregation via liquid-liquid phase separation.