Novel role of β-arrestins in Tauopathy

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The major defining pathological hallmarks of Alzheimer’s disease (AD) are the accumulation of amyloid β (Aβ) and hyperphosphorylated tau. Multiple GPCRs (i.e, β2AR, GPR3, AT2R, CXCR2, & NMDARs) have been shown to play integral roles in AD pathogenesis. However, it is unclear as to how a diverse array of GPCRs all positively impinge on Aβ and tau pathogenesis as well as neurodegeneration in AD. Given that GPCRs share a common mechanism of action via β-arrestin scaffolding signaling complexes, the central hypothesis is that the actions of β-arrestins downstream of GPCRs directly impact AD pathogenesis. β-arrestins exist in three distinct states in cells; 1) free unbound, 2) GPCR-bound, and 3) microtubule-bound, each with different signaling capability. Previous studies have shown that β-arrestins are upregulated in AD brains and that β- arrestins promote Aβ pathogenesis. However, it is unknown whether and how β-arrestins pathogenically impinge on tauopathy and neurodegeneration in AD. Preliminary data indicate that β-arrestin oligomers promote tauopathy via 2 distinct mechanisms: 1) directly competing with tau for binding to microtubules (MT), thereby deregulating MT dynamics; 2) inhibiting tau clearance by deregulating the autophagy machinery. By utilizing molecular, cell biological, biochemical, electrophysiological, behavioral, viral, and histochemical tools, this proposal will 1) validate the role of β-arrestins in tauopathy in vivo, 2) validate the role of β-arrestins in tau/microtubule dynamics, and 3) investigate the role of β- arrestins in p62-mediated autophagy and tau turnover. This proposal will validate whether β- arrestins and their oligomeric status serve as promising therapeutic targets to mitigate tau pathogenesis.