Synaptic activity-responsive element in the Arc / Arg3.1 promoter essential for synapse-to-nucleus signaling in activated neurons

Abstract

The neuronal immediate early gene Arc/Arg-3.1 is widely used as one of the most reliable molecular markers for intense synaptic activity in vivo. However, the cis-acting elements responsible for such stringent activity dependence have not been firmly identified. Here we combined luciferase reporter assays in cultured cortical neurons and comparative genome mapping to identify the critical synaptic activityresponsive elements (SARE) of the Arc/Arg-3.1 gene. A major SARE was found as a unique Ϸ100-bp element located at >5 kb upstream of the Arc/Arg-3.1 transcription initiation site in the mouse genome. This single element, when positioned immediately upstream of a minimal promoter, was necessary and sufficient to replicate crucial properties of endogenous Arc/Arg-3.1's transcriptional regulation, including rapid onset of transcription triggered by synaptic activity and low basal expression during synaptic inactivity. We identified the major determinants of SARE as a unique cluster of neuronal activitydependent cis-regulatory elements consisting of closely localized binding sites for CREB, MEF2, and SRF. Consistently, a SARE reporter could readily trace and mark an ensemble of cells that have experienced intense activity in the recent past in vivo. Taken together, our work uncovers a novel transcriptional mechanism by which a critical 100-bp element, SARE, mediates a predominant component of the synapse-to-nucleus signaling in ensembles of Arc/Arg-3.1-positive activated neurons.immediate-early genes ͉ MEF2 ͉ SRF ͉ calcium ͉ CREB

Class I Histone Deacetylase-mediated Repression of the Proximal Promoter of the Activity-regulated Cytoskeleton-associated Protein Gene Regulates Its Response to Brain-derived Neurotrophic Factor

“…Previous studies have established that the expression of Arc is activated by neuronal activity (1,2,4,5). Consistent with this finding, we found that the expression of Arc mRNA was also increased by the direct activation of NMDA receptor (NMDAR) with exogenously added NMDA (Fig.…”

“…9), although the distal enhancer, SARE, has previously been shown to play a crucial role in activity-dependent Arc expression (4). Arc/Ϫ7000 and Arc/SARE were activated by NMDAR activation, whereas Arc/Ϫ1679 was activated by BDNF or FGF2, but not by NMDA.…”

“…In neurons, Arc expression is regulated by various stimuli including not only neuronal activity, but also BDNF, cAMP, and PDGF (3)(4)(5)(6). Arc mRNA has been detected in cell bodies, dendrites, and spines after stimulation (7,8), and the Arc protein could be synthesized locally at dendritic spines (9,10).…”

“…Thus, Arc is a unique molecule involved in the control of synaptic plasticity (10,13,14). Kawashima et al (4) demonstrated that a distal enhancer, synaptic activity-responsive element (SARE), which contains binding sites for cAMP-response element (CRE)-binding protein (CREB), myocyte enhancer factor 2 (MEF2), and serum response factor (SRF), located Ϫ7 kbp upstream of the Arc transcription start site, was essential for activity-dependent transcriptional activation of Arc (4). In addition, Pintchovski et al (5) reported that a serum response element (SRE) located in SARE, and a Zeste-like element were also involved in the transcriptional activation of the Arc promoter.…”

Untangling the two-way signalling route from synapses to the nucleus, and from the nucleus back to the synapses

“…By carefully examining the promoter and the distal regulatory elements critical for activity-dependent neuronal expression, we were indeed able to identify a CRE half-site that functioned as a genuine CREBregulated locus, within the synaptic activity-responsive element (SARE), a distal enhancer region located at about 7-kb upstream of the Arc's transcription start site [54,55]. Strikingly, the SARE of the Arc gene consisted of a unique cluster of binding sites for CREB, MEF2 and SRF/TCF, each of which cooperatively contributed to converting synaptic inputs into a transcriptional output (figure 2b).…”