BIN1 Interacts with Tau Fragments to Inhibit TrkB Signaling Endosome Recycling in a Mouse Model of Alzheimer's Disease.

Deficits in BDNF/TrkB receptor signaling lead to increased asparagine endopeptidase activity, which cleaves Tau at the N368 residue to promote Tau hyperphosphorylation and aggregation, thereby contributing to neuronal dysfunction in Alzheimer's disease (AD). However, whether Tau N368 inhibits the BDNF/TrkB signaling pathway remains poorly understood. Previous studies have shown that the internalization of the BDNF/TrkB complex, which leads to signaling endosomes, is necessary for coordinating neuronal survival and synaptic plasticity. Here, we demonstrate that Bridging Integrator 1 (BIN1) interacts with the Tau fragment N368 in P301S and Tau N368-Tg mouse brains, inhibiting BDNF/TrkB signaling by obstructing their early-endosome recycling. Overexpression of BIN1 in the hippocampus of Tau N368-Tg mice partially rescues BDNF/TrkB endosome transport and alleviates pathological and behavioral defects. Our findings suggest that dysfunction of the early-endosome pathway mediated by the Tau N368-BIN1 interaction impairs BDNF signaling, contributing to AD-associated pathological and behavioral dysfunction.