BIN1 recovers tauopathy-induced long-term memory deficits in mice and interacts with Tau through Thr348 phosphorylation

Abstract

The bridging integrator 1 gene (BIN1) is a major genetic risk factor for Alzheimer’s disease (AD). In this report, we investigated how BIN1-dependent pathophysiological processes might be associated with Tau. We first generated a cohort of control and transgenic mice either overexpressing human MAPT (TgMAPT) or both human MAPT and BIN1 (TgMAPT;TgBIN1), which we followed-up from 3 to 15 months. In TgMAPT;TgBIN1 mice short-term memory deficits appeared earlier than in TgMAPT mice; however—unlike TgMAPT mice—TgMAPT;TgBIN1 mice did not exhibit any long-term or spatial memory deficits for at least 15 months. After killing the cohort at 18 months, immunohistochemistry revealed that BIN1 overexpression prevents both Tau mislocalization and somatic inclusion in the hippocampus, where an increase in BIN1–Tau interaction was also observed. We then sought mechanisms controlling the BIN1–Tau interaction. We developed a high-content screening approach to characterize modulators of the BIN1–Tau interaction in an agnostic way (1,126 compounds targeting multiple pathways), and we identified—among others—an inhibitor of calcineurin, a Ser/Thr phosphatase. We determined that calcineurin dephosphorylates BIN1 on a cyclin-dependent kinase phosphorylation site at T348, promoting the open conformation of the neuronal BIN1 isoform. Phosphorylation of this site increases the availability of the BIN1 SH3 domain for Tau interaction, as demonstrated by nuclear magnetic resonance experiments and in primary neurons. Finally, we observed that although the levels of the neuronal BIN1 isoform were unchanged in AD brains, phospho-BIN1(T348):BIN1 ratio was increased, suggesting a compensatory mechanism. In conclusion, our data support the idea that BIN1 modulates the AD risk through an intricate regulation of its interaction with Tau. Alteration in BIN1 expression or activity may disrupt this regulatory balance with Tau and have direct effects on learning and memory.Electronic supplementary materialThe online version of this article (10.1007/s00401-019-02017-9) contains supplementary material, which is available to authorized users.

High‐Content Screening for Protein‐Protein Interaction Modulators Using Proximity Ligation Assay in Primary Neurons

“…Exclusion of one of the primary antibodies or one of the PLA probes is sufficient to ensure the quality of the PLA reaction and assess the background PLA signal; however, the specificity and sensitivity of the PLA technique is best assessed by underexpressing one (or preferably each) of the target proteins. For example, we confirmed the specificity of BIN1‐tau PLA by underexpression of the neuronal isoform of BIN1 (via lentiviral transduction of the corresponding short hairpin RNA), which resulted in an ∼2‐fold decrease in PLA density (Sartori et al., ). It is recommended that quality‐control and optimization experiments be conducted using neurons cultured on glass coverslips, before moving to 384‐well plates.…”

Molecular and cellular mechanisms underlying the pathogenesis of Alzheimer’s disease

“…Although results with respect to whether BIN1 can affect AD pathogenesis remain controversial, it seems that BIN1 may affect AD risk by regulating tau pathology. BIN1 overexpression has been shown to reverse memory deficits in tau transgenic mice, and neuronal BIN1 expression is inversely correlated with pathological tau propagation [478,479]. However, deletion of BIN1 in microglia reduces tau secretion and spreading in PS19 tau transgenic mice, suggesting BIN1 may act differentially in neurons and microglia.…”

Yeast as a Model to Understand Actin-Mediated Cellular Functions in Mammals—Illustrated with Four Actin Cytoskeleton Proteins

“…The sites of interaction between Tau and BIN1 were mapped to the SH3 domain of BIN1 and the PRD domain of Tau, with phosphorylation in and around the PRD decreasing the binding to BIN1 SH3 in vitro and in vivo [289]. Moreover, phosphorylation of BIN1 at position T348 increases the availability of the SH3 domain for Tau binding, and in AD brains the level of phospho-T348 BIN1 was increased compared to BIN1 [290].…”