Experience-induced remodeling of the hippocampal post-synaptic proteome and phosphoproteome

Abstract

SummaryThe post synaptic density (PSD) of excitatory synapses contains a highly organized protein network with thousands of proteins and is key node in the regulation of synaptic plasticity. To gain new mechanistic insight into experience-induced changes in the PSD, we examined the global dynamics of the PSD proteome and phosphoproteome in mice following various treatments. Mice were trained using an inhibitory avoidance (IA) task and hippocampal PSD fractions were isolated for quantitative proteomic and phosphoproteomics analysis. We used a sequential enrichment strategy to explore the concurrent events of protein expression and phosphorylation in the hippocampal PSD following IA training (IA) or immediate shock (Shock). We identified more than 6,200 proteins and 3,000 phosphoproteins in the sequential strategy covering a total of 7,429 proteins. On the phosphoproteins we identified a total of 9,589 phosphosites. Strikingly, of the significantly IA-regulated proteins and phosphoproteins, a large fraction of the proteins displayed an overall decrease in phosphorylation level. Bioinformatic analysis of proteins and phosphoproteins that were regulated by IA were annotated for an involvement in regulation of glutamate receptor functionality, calcium signaling, and synaptic plasticity. We also identified synaptic kinases, phosphatases and their respective phosphosites regulated by IA training or immediate shock. Furthermore, we found that AMPA receptor surface expression was regulated by protein phosphatase, Mg2+/Mn2+ dependent 1H (Ppm1h). Together, these results unravel the dynamic remodeling of the PSD upon IA learning or immediate shock and serve as a resource for elucidating the synaptic proteome dynamics induced by experience-dependent plasticity.HighlightsThe proteome and phosphoproteome of mouse hippocampal PSD fractions were examined using quantitative phosphoproteomics and bioinformatics following inhibitory avoidance training or non-associative immediate shock.Approximately 6,200 proteins and 3,000 phosphoproteins were identified and quantified in the hippocampal PSD fractions.IA mediates widespread decreases in the abundance and phosphorylation of proteins in the hippocampal PSD fraction.Kinases, phosphatases and their phosphorylation status were dynamically and significantly regulated by IA and immediate shock.Functional validation shows that the protein phosphatase Ppm1h is linked to the regulation of synaptic plasticity in vitro and in vivo.In BriefQuantitative proteomics and phosphoproteomics combined with subcellular protein fractionation and bioinformatic analysis identifies a highly dynamic regulation of synaptic protein phosphorylation at the postsynaptic density following IA training and immediate shock.

Synaptic activity–dependent changes in the hippocampal palmitoylome

“…To better understand the molecular underpinnings of learning and memory, various experimental in vivo learning models have been used to study activity-mediated changes in the hippocampal proteome (22), synaptic proteome (23), and synaptosomal phosphoproteome (24). Contextual fear conditioning (cFC) is an experimental model for fear learning in which animals rapidly learn to associate a given environment with a single brief foot shock (25,26), allowing for experimental observations at distinct time points after the acquisition event.…”

Phosphorylation of PLPPR3 membrane proteins as signaling integrator at neuronal synapses

“…Adding further evidence, phosphoproteome studies consistently find PLPPR3 pS351 in synaptic fractions. 45,[55][56][57][58] Taken together, these data indicate that PLPPR3 is a synaptic protein. It is tempting to speculate that phosphorylation may be the regulatory switch between different PLPPR3 functions.…”