Dynamic Arc SUMOylation and Selective Interaction with F-Actin-Binding Protein Drebrin A in LTP Consolidation In Vivo

Abstract

Activity-regulatedcytoskeleton-associated protein (Arc) protein is implicated as a master regulator of long-term forms of synaptic plasticity and memory formation, but the mechanisms controlling Arc protein function are little known. Post-translation modification by small ubiquitin-like modifier (SUMO) proteins has emerged as a major mechanism for regulating protein-protein interactions and function. We first show in cell lines that ectopically expressed Arc undergoes mono-SUMOylation. The covalent addition of a single SUMO1 protein was confirmed by in vitro SUMOylation of immunoprecipitated Arc. To explore regulation of endogenous Arc during synaptic plasticity, we induced long-term potentiation (LTP) in the dentate gyrus of live anesthetized rats. Using coimmunoprecipitation of native proteins, we show that Arc synthesized during the maintenance phase of LTP undergoes dynamic mono-SUMO1-ylation. Levels of unmodified Arc increase in multiple subcellular fractions (cytosol, membrane, nuclear and cytoskeletal), whereas enhanced Arc SUMOylation was specific to the synaptoneurosomal and the cytoskeletal fractions. Dentate gyrus LTP consolidation requires a period of sustained Arc synthesis driven by brain-derived neurotrophic factor (BDNF) signaling. Local infusion of the BDNF scavenger, TrkB-Fc, during LTP maintenance resulted in rapid reversion of LTP, inhibition of Arc synthesis and loss of enhanced Arc SUMO1ylation. Furthermore, coimmunoprecipitation analysis showed that SUMO1-ylated Arc forms a complex with the F-actin-binding protein drebrin A, a major regulator of cytoskeletal dynamics in dendritic spines. Although Arc also interacted with dynamin 2, calcium/calmodulindependentprotein kinase II-beta (CaMKIIβ), and postsynaptic density protein-95 (PSD-95), these complexes lacked SUMOylated Arc. The results support a model in which newly synthesized Arc is SUMOylated and targeted for actin cytoskeletal regulation during in vivo LTP.

Arc Regulates Transcription of Genes for Plasticity, Excitability and Alzheimer’s Disease

“…Here, Arc controls the removal of AMPA receptors by endocytosis, allowing it to regulate synaptic efficacy 14,17 . Synaptic Arc also associates with the synaptic scaffolding protein PSD-95/Dlg4, which complexes with the tyrosine kinase FYN [186][187][188] , allowing it to regulate brain-derived neurotrophic factor (BDNF) signalling through tyrosine receptor kinase B (TrkB), a major pathway for synapse maturation, plasticity and neurodevelopmental disorders 189 . Activation of FYN could also mediate the secretion of TNF 190 (Fig.…”

Gq-mediated calcium dynamics and membrane tension modulate neurite plasticity

“…We expected that transfection of the cells with drebrin would strongly impede neurite retraction in the presence of carbachol because drebrin is known to bind assembled actin filaments (F-actin) and stabilize them (41,45,46). Low amounts of actin allowed a sustained linear decrease (Fig.…”

Molecular determinants of Arc oligomerization and formation of virus-like capsids

“…Loss of function studies support a role for Arc in long-term potentiation (LTP) and long-term depression (LTD) of synaptic transmission and homeostatic synaptic scaling. These diverse responses are mediated by distinct Arc protein-protein interaction complexes in the postsynaptic dendritic compartment and the neuronal nucleus (Chowdhury et al, 2006;DaSilva et al, 2016;Korb et al, 2013;Nair et al, 2017;Okuno et al, 2012;Zhang et al, 2015). Thus, convergent lines of evidence support a role for Arc as a signaling hub protein and cell-autonomous organizer of synaptic plasticity .…”

“…The mechanisms that dictate Arc function at the molecular level are poorly understood. Posttranslational modification of Arc by SUMOylation (Craig et al, 2012;Nair et al, 2017) and ERKcatalyzed phosphorylation are implicated in the regulation of protein-protein interactions and subcellular localization, while Arc turnover is regulated by ubiquitination, acetylation, as well as GSK-catalyzed phosphorylation (Gozdz et al, 2017;Greer et al, 2010;Lalonde et al, 2017;Mabb et al, 2014;Wall et al, 2018). In addition, biochemical studies show that recombinant Arc protein is capable of reversible self-association (Byers et al, 2015;Myrum et al, 2015).…”