Identification of the novel activity-driven interaction between synaptotagmin 1 and presenilin 1 links calcium, synapse, and amyloid beta

Abstract

Background: Synaptic loss strongly correlates with memory deterioration. Local accumulation of amyloid β (Aβ) peptide, and neurotoxic Aβ42 in particular, due to abnormal neuronal activity may underlie synaptic dysfunction, neurodegeneration, and memory impairments. To gain an insight into molecular events underlying neuronal activity-regulated Aβ production at the synapse, we explored functional outcomes of the newly discovered calcium-dependent interaction between Alzheimer’s disease-associated presenilin 1 (PS1)/γ-secretase and synaptic vesicle proteins. Results: Mass spectrometry screen of mouse brain lysates identified synaptotagmin 1 (Syt1) as a novel synapse-specific PS1-binding partner that shows Ca2+-dependent PS1 binding profiles in vitro and in vivo. We found that Aβ level, and more critically, conformation of the PS1 and the Aβ42/40 ratio, are affected by Syt1 overexpression or knockdown, indicating that Syt1 and its interaction with PS1 might regulate Aβ production at the synapse. Moreover, β-secretase 1 (BACE1) stability, β- and γ-secretase activity, as well as intracellular compartmentalization of PS1 and BACE1, but not of amyloid precursor protein (APP), nicastrin (Nct), presenilin enhancer 2 (Pen-2), or synaptophysin (Syp) were altered in the absence of Syt1, suggesting a selective effect of Syt1 on PS1 and BACE1 trafficking. Conclusions: Our findings identify Syt1 as a novel Ca2+-sensitive PS1 modulator that could regulate synaptic Aβ, opening avenues for novel and selective synapse targeting therapeutic strategies. Electronic supplementary material The online version of this article (doi:10.1186/s12915-016-0248-3) contains supplementary material, which is available to authorized users.