AbstractBackgroundFilamentous actin (F‐actin) is the major cytoskeleton protein present in dendritic spines and it is an essential element for defining dendritic spine structure. We have shown that synaptosomal F‐actin levels were significantly decreased in APP/PS1 mice as early as 1 month of age. Further, reduced form of F‐actin is diminished and glutathionylated F‐actin is significantly increased in synaptosomes of 1 month old APP/PS1 mice. Synaptic neurotransmission and synaptic plasticity are dependent on the dynamic regulation of the actin through actin‐interacting and actin‐modulating proteins. Recent studies highlight that F‐actin nanoarchitecture is susceptible to several key regulators such as reactive oxygen species, cofilin and drebrin that are present in the dendritic spines. Yet, how synaptosomal F‐actin organization is regulated remains poorly understood. To address this, we characterized actin interactome in synaptosomes prepared from wild type and APPSwe/PS1ΔE9 (APP/PS1) mice.MethodsWe utilized age matched wild type (WT) and APP/PS1 mice for our experiments. Synaptosomes and highly enriched F‐actin and G‐actin fractions from synaptosomes were isolated from WT and APP/PS1 mice. We performed immunoprecipitation using all these fractions with an anti‐actin polyclonal antibody and eluted in Laemmli sample buffer. The IP elutes were resolved using SDS‐PAGE gels, all proteins purified from gels, and analysed by LC‐MS/MS spectrometry.ResultsWe detected approximately 620 synaptic proteins in synaptosomes from both wild type and APP/PS1 mice at the age of six months. About 110 proteins were upregulated and 198 proteins down regulated in synaptosomes of APP/PS1 mice. We identified 69 proteins that were associated with F‐actin in WT mice while only 26 proteins interacted with F‐actin in APP/PS1 mice in synaptosomal F‐actin fraction. Further, we detected G‐actin‐interaction only with 10 proteins in WT and 15 proteins in APP/PS1 mice in synaptosomal G‐actin fraction. However, we were able to identify 401 proteins in WT and 444 proteins with F/G‐actin‐association in synaptosomes of APP/PS1 mice compared with WT mice.ConclusionsOur result defines a provisional synaptosomal actin interactome in mouse brain cortex of WT and APP/PS1 mice and identifies several critical regulator proteins that may be involved in the progression of AD pathogenesis.