Arc 3′ UTR Splicing Leads to Dual and Antagonistic Effects in Fine-Tuning Arc Expression Upon BDNF Signaling

Abstract

Activity-regulated cytoskeletal associated protein (Arc) is an immediate-early gene critically involved in synaptic plasticity and memory consolidation. Arc mRNA is rapidly induced by synaptic activation and a portion is locally translated in dendrites where it modulates synaptic strength. Being an activity-dependent effector of homeostatic balance, regulation of Arc is uniquely tuned to result in short-lived bursts of expression. Cis-Acting elements that control its transitory expression post-transcriptionally reside primarily in Arc mRNA 3′ UTR. These include two conserved introns which distinctively modulate Arc mRNA stability by targeting it for destruction via the nonsense mediated decay pathway. Here, we further investigated how splicing of the Arc mRNA 3′ UTR region contributes to modulate Arc expression in cultured neurons. Unexpectedly, upon induction with brain derived neurotrophic factor, translational efficiency of a luciferase reporter construct harboring Arc 3′ UTR is significantly upregulated and this effect is dependent on splicing of Arc introns. We find that, eIF2α dephosphorylation, mTOR, ERK, PKC, and PKA activity are key to this process. Additionally, CREB-dependent transcription is required to couple Arc 3′ UTR-splicing to its translational upregulation, suggesting the involvement of de novo transcribed trans-acting factors. Overall, splicing of Arc 3′ UTR exerts a dual and unique effect in fine-tuning Arc expression upon synaptic signaling: while inducing mRNA decay to limit the time window of Arc expression, it also elicits translation of the decaying mRNA. This antagonistic effect likely contributes to the achievement of a confined yet efficient burst of Arc protein expression, facilitating its role as an effector of synapse-specific plasticity.

Upf1 regulates neurite outgrowth and branching by transcriptional and post-transcriptional modulation of Arc

“…Arc has a long 3′UTR, consisting of 1670 nts, so we tried to reveal another possible role for Upf1 in the translation of Arc. Additionally, the Arc mRNA 3′UTR region was reported to contribute to the modulation of Arc expression upon BDNF treatment (Paolantoni et al, 2018). By in vitro binding assay, we first confirmed that Upf1 binds to the 3′UTR of Arc regardless of the EJC, which shows the possible effects of Upf1 on posttranscriptional regulation of Arc.…”

Nonsense-mediated RNA decay in the brain: emerging modulator of neural development and disease

“…1 and 2). The ability of these 2 introns to trigger NMD was recently directly shown in reporter experiments 85 . Second, Arc mRNA is bound by eIF4A3 81 .…”

“…Thus, the instability of the Arc mRNA, coupled with its rapid transcriptional induction, allows ARC protein to be strongly and transiently expressed in activated neurons. Of note, it was recently shown that ARC translation is stimulated by brain-derived neurotrophic factor through a RNA splicing- and 3’UTR-dependent mechanism 85 . This provides another level of regulation (also acting through the 3’UTR) that drives the unique expression pattern of ARC in neurons.…”

Deletion of Stk11 and Fos in mouse BLA projection neurons alters intrinsic excitability and impairs formation of long-term aversive memory

“…Opposing changes in STK11 protein and mRNA levels could reflect homeostatic control of this powerful signaling pathway. Translation-dependent feedback of some other proteins is known to reduce mRNA levels through nonsense-mediated decay ( Giorgi et al, 2007 ; Paolantoni et al, 2018 ) or other forms of mRNA degradation ( Lin et al, 2020 ; Shoshani and Cleveland, 2020 ). Complex feedback control involving changes in RNA export and stability has also been described for MAP kinase signaling ( Sugiura et al, 2003 ; Prieto-Ruiz et al, 2020 ), but whether this type of regulation exists for Stk11 and the AMP-related kinase pathway remains unknown.…”