A peptide inhibitor of Tau-SH3 interactions ameliorates amyloid-β toxicity

Abstract

The microtubule-associated protein Tau is strongly implicated in Alzheimer's disease (AD) and aggregates into neurofibrillary tangles in AD. Genetic reduction of Tau is protective in several animal models of AD and cell culture models of amyloid-β (Aβ) toxicity, making it an exciting therapeutic target for treating AD. A variety of evidence indicates that Tau's interactions with Fyn kinase and other SH3 domain-containing proteins, which bind to PxxP motifs in Tau's proline-rich domain, may contribute to AD deficits and Aβ toxicity. Thus, we sought to determine if inhibiting Tau-SH3 interactions ameliorates Aβ toxicity. We developed a peptide inhibitor of Tau-SH3 interactions and a proximity ligation assay (PLA)-based target engagement assay. Then, we used membrane trafficking and neurite degeneration assays to determine if inhibiting Tau-SH3 interactions ameliorated Aβ oligomer (Aβo)-induced toxicity in primary hippocampal neurons from rats. We verified that Tau reduction ameliorated Aβo toxicity in neurons. Using PLA, we identified a peptide inhibitor that reduced Tau-SH3 interactions in HEK-293 cells and primary neurons. This peptide reduced Tau phosphorylation by Fyn without affecting Fyn's kinase activity state. In primary neurons, endogenous Tau-Fyn interaction was present primarily in neurites and was reduced by the peptide inhibitor, from which we inferred target engagement. Reducing Tau-SH3 interactions in neurons ameliorated Aβo toxicity by multiple outcome measures, namely Aβo-induced membrane trafficking abnormalities and neurite degeneration. Our results indicate that Tau-SH3 interactions are critical for Aβo toxicity and that inhibiting them is a promising therapeutic target for AD.

Fyn depletion ameliorates tauP301L-induced neuropathology

“…However, given the importance of Fyn in normal physiological processes, such therapy would be difficult, especially since dementia patients usually have reduced cognitive reserves. Thus, more specific therapies aimed at targeting either disease related processes involving Fyn or Fyn interaction partners may yield a more desirable therapeutic result; the recent report of a peptide inhibitor of the tau-Fyn interaction [ 65 ] is a first step in this direction. In closing, as Aβ oligomers had no role in these findings, Fyn alone has an important role in tauopathy.…”

“…In addition, pY18-tau also co-localized with activated Src family tyrosine kinases (SFK) in NFTs of FTDP-17 mouse brains [ 2 ]. In Aβ-mediated neurodegeneration, the importance of the tau-Fyn interaction has been supported by the finding that inhibition of the interaction ameliorated the toxic effects of Aβ oligomers [ 65 ].…”

Alzheimer’s disease risk gene BIN1 induces Tau-dependent network hyperexcitability

“…We then tested the hypothesis that Tau affects the BIN1–LVGCCβ1 interaction, using the BIN1–LVGCC-β1 PLA assay with and without pretreatment with Tau antisense oligonucleotide (ASO) ( Figure 5D ). We recently demonstrated that this ASO reduces Tau protein by about 50% under these conditions ( Rush et al, 2020 ). Tau reduction decreased BIN1–LVGCC-β1 interaction in primary hippocampal neurons, compared to neurons treated with a scrambled control ASO ( Figure 5E ), indicating that in cultured neurons the BIN1–LVGCC-β1 interaction is partially Tau-dependent.…”

Frontotemporal dementia mutant tau (P301L) locks Fyn in an open, active conformation conducive to nanoclustering

“…However, undesired effects such as memory deficits associated with the absence of Fyn (Grant et al, 1992) suggest that further investigations are required to achieve more desirable therapeutic results. The recent development of a cell-permeable peptide inhibitor of the Fyn-tau interaction yielded promising results, reducing the endogenous Fyn-tau interaction and tau phosphorylation (Rush et al, 2020). G9 monobodies have also been used, demonstrating efficiency in inhibiting Fyn-tau binding (Cochran et al, 2014).…”