MicroRNA Regulation of the Synaptic Plasticity-Related Gene Arc

Abstract

Expression of activity-regulated cytoskeleton associated protein (Arc) is crucial for diverse types of experience-dependent synaptic plasticity and long-term memory in mammals. However, the mechanisms governing Arc-specific translation are little understood. Here, we asked whether Arc translation is regulated by microRNAs. Bioinformatic analysis predicted numerous candidate miRNA binding sites within the Arc 3′-untranslated region (UTR). Transfection of the corresponding microRNAs in human embryonic kidney cells inhibited expression of an Arc 3′UTR luciferase reporter from between 10 to 70% across 16 microRNAs tested. Point mutation and deletion of the microRNA-binding seed-region for miR-34a, miR-326, and miR-19a partially or fully rescued reporter expression. In addition, expression of specific microRNA pairs synergistically modulated Arc reporter expression. In primary rat hippocampal neuronal cultures, ectopic expression of miR-34a, miR-193a, or miR-326, downregulated endogenous Arc protein expression in response to BDNF treatment. Conversely, treatment of neurons with cell-penetrating, peptide nucleic acid (PNA) inhibitors of miR-326 enhanced Arc mRNA expression. BDNF dramatically upregulated neuronal expression of Arc mRNA and miR-132, a known BDNF-induced miRNA, without affecting expression of Arc-targeting miRNAs. Developmentally, miR-132 was upregulated at day 10 in vitro whereas Arc-targeting miRNAs were downregulated. In the adult brain, LTP induction in the dentate gyrus triggered massive upregulation of Arc and upregulation of miR-132 without affecting levels of mature Arc-targeting miRNAs. Turning to examine miRNA localization, qPCR analysis of dentate gyrus synaptoneurosome and total lysates fractions demonstrated synaptic enrichment relative to small nucleolar RNA. In conclusion, we find that Arc is regulated by multiple miRNAs and modulated by specific miRNA pairs in vitro. Furthermore, we show that, in contrast to miR-132, steady state levels of Arc-targeting miRNAs do not change in response to activity-dependent expression of Arc in hippocampal neurons in vitro or during LTP in vivo.

MicroRNA-137 Controls AMPA-Receptor-Mediated Transmission and mGluR-Dependent LTD

“…Consistent with these notions, inducing LTP or LTD rapidly alters the levels of many different miRNAs in hippocampal neurons (Park and Tang, 2009;Wibrand et al, 2010). MiRNAs affect synaptic plasticity by directly targeting synaptic receptors or their downstream targets (Dutta et al, 2013;Fiore et al, 2014;Kocerha et al, 2009;Letellier et al, 2014;Saba et al, 2012;Schratt et al, 2006), including LTD proteins such as Arc and Map1b (Chen and Shen, 2013;Wibrand et al, 2012). These findings suggest that variation in miRNA expression affects synaptic protein levels and, consequently, synaptic plasticity by controlling the stability and translation of dendritically localized transcripts.…”

Epigenetics and ncRNAs in Brain Function and Disease: Mechanisms and Prospects for Therapy

“…Treatment with LNA antisense oligonucleotides decreased the levels of miR-21 in glioblastoma cell lines [132] and miR-219 in cortex [128,133]. Similarly, peptide nucleic acids (PNAs) delivered into neurons decreased miR-326 activity and caused an increase in expression of synaptic plasticity genes [134].…”

Consolidation and translation regulation: Figure 1.

“…miR-34a regulates, on the other hand, SIRT1 in the context of neuronal stem-cell differentiation (Aranha et al 2011). A recent study has identified miR-34a as one of three miRNAs that cooperates in regulation of the Arc 3 ′ UTR and which inhibits endogenous Arc protein expression in neurons (Wibrand et al 2012).…”