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Arc UTRs are not required for Arc induction. A, fluorescence signals of neurons expressing Arc- EYFP (without UTRs) and ECFP treated with vehicle or forskolin (Forsk) for 4 h. Exposure times for the Arc-EYFP signals were 1600 ms, 200 ms, and 8 s, respectively, whereas they were 400 ms for ECFP. Arc is enriched in the soma with lower levels in the dendrites. Forskolin treatment increased the expression of Arc protein both in the soma and dendrites in a punctate manner. Scale bars are 10, 10, and 5 m. B, quantification of yellow and cyan fluorescence signal from neurons expressing Arc-EYFP (without UTRs) and ECFP. Neurons were treated with forskolin for different time periods. Cultures were treated so that all cells were fixed at the same time. Arc expression peaks at 4 h. C, effect of agonists on yellow and cyan fluorescence signals in neurons co-expressing Arc-EYFP (lacking UTRs) and ECFP. All agonists (except 8-CPT) increased Arc expression while having only a minimal effect on ECFP. The profile was as follows: forskolin 8-Br-cAMP NMDA plus forskolin NMDA plus SKF-38393 NMDA SKF-38393. D, quantification of Arc-EYFP/ECFP ratio in cells pretreated with vehicle or 20 M H89 for 1 h followed by a 4-h treatment with agonists. H89 blocked the effect of all the agonists on Arc expression level.  

Arc UTRs are not required for Arc induction. A, fluorescence signals of neurons expressing Arc- EYFP (without UTRs) and ECFP treated with vehicle or forskolin (Forsk) for 4 h. Exposure times for the Arc-EYFP signals were 1600 ms, 200 ms, and 8 s, respectively, whereas they were 400 ms for ECFP. Arc is enriched in the soma with lower levels in the dendrites. Forskolin treatment increased the expression of Arc protein both in the soma and dendrites in a punctate manner. Scale bars are 10, 10, and 5 m. B, quantification of yellow and cyan fluorescence signal from neurons expressing Arc-EYFP (without UTRs) and ECFP. Neurons were treated with forskolin for different time periods. Cultures were treated so that all cells were fixed at the same time. Arc expression peaks at 4 h. C, effect of agonists on yellow and cyan fluorescence signals in neurons co-expressing Arc-EYFP (lacking UTRs) and ECFP. All agonists (except 8-CPT) increased Arc expression while having only a minimal effect on ECFP. The profile was as follows: forskolin 8-Br-cAMP NMDA plus forskolin NMDA plus SKF-38393 NMDA SKF-38393. D, quantification of Arc-EYFP/ECFP ratio in cells pretreated with vehicle or 20 M H89 for 1 h followed by a 4-h treatment with agonists. H89 blocked the effect of all the agonists on Arc expression level.  

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Arc/Arg3.1 is an immediate early gene whose expression is necessary for the late-phase of long-term potentiation (LTP) and memory consolidation. Whereas pathways regulating Arc transcription have been extensively investigated, less is known about the role of post-transcriptional mechanisms in Arc expression. Fluorescence microscopy experiments in c...

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Context 1
... of UTRs in the Arc mRNA. Experiments were performed with an Arc construct that lacked both the 5-and 3-UTRs. The 3-UTR of Arc has previously been shown to be impor- tant in dendritic targeting, although its role in Arc protein translation is unknown (28). A plasmid encoding Arc-EYFP without the UTRs was co-expressed with ECFP in cultured neurons (Fig. 3). Again, forskolin treatment caused Arc to be up-reg- ulated (notice the difference in exposure times), whereas its distri- bution became more punctuate in the soma and dendrites (Fig. ...
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... although its role in Arc protein translation is unknown (28). A plasmid encoding Arc-EYFP without the UTRs was co-expressed with ECFP in cultured neurons (Fig. 3). Again, forskolin treatment caused Arc to be up-reg- ulated (notice the difference in exposure times), whereas its distri- bution became more punctuate in the soma and dendrites (Fig. ...
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... cultures were stimu- lated with forskolin for different time periods over 24 h. Arc expres- sion ratios peaked at 4 h, with a 7.6- fold increase over unstimulated neurons (Fig. 3B). Transfected cul- tures were also stimulated with the PKA agonists (Fig. 3C). All the pre- viously used agonists increased Arc- EYFP expression, while having a marginal effect on ECFP. Arc expression ratios increased 8-fold for forskolin and 8-Br-cAMP, 4-fold for NMDA, 3.2-fold for SKF-38393, and additively 7.6-fold for NMDA plus ...
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... cultures were stimu- lated with forskolin for different time periods over 24 h. Arc expres- sion ratios peaked at 4 h, with a 7.6- fold increase over unstimulated neurons (Fig. 3B). Transfected cul- tures were also stimulated with the PKA agonists (Fig. 3C). All the pre- viously used agonists increased Arc- EYFP expression, while having a marginal effect on ECFP. Arc expression ratios increased 8-fold for forskolin and 8-Br-cAMP, 4-fold for NMDA, 3.2-fold for SKF-38393, and additively 7.6-fold for NMDA plus SKF-38393 stimulation. NMDA stimulation did not enhance the forskolin effect, ...
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... increased 8-fold for forskolin and 8-Br-cAMP, 4-fold for NMDA, 3.2-fold for SKF-38393, and additively 7.6-fold for NMDA plus SKF-38393 stimulation. NMDA stimulation did not enhance the forskolin effect, possibly because forskolin has already saturated the signaling pathway. Again, the PKA antagonist H89 blocked the effect of all agonists tested (Fig. 3D). The two main effectors of cAMP are PKA and Epac, an activator of the small G-protein Rap1. To investi- gate a possible involvement of Epac in the regulation of Arc expression, we used 8-CPT, a cAMP analogue that specifically activates Epac. 8-CPT was com- pletely ineffective, further verify- ing that cAMP acted specifically through ...
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... (Fig. 3D). The two main effectors of cAMP are PKA and Epac, an activator of the small G-protein Rap1. To investi- gate a possible involvement of Epac in the regulation of Arc expression, we used 8-CPT, a cAMP analogue that specifically activates Epac. 8-CPT was com- pletely ineffective, further verify- ing that cAMP acted specifically through PKA (Fig. 3C). These data show that Arc expression is regu- lated through the cAMP/PKA path- way in hippocampal neurons by a mechanism that does not require the UTRs of ...

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... Arc transcription can be regulated, among others, by NMDA receptors, second messengers, protein kinases, and transcription factors [18,48,63]. Additionally, Arc can be regulated post-transcriptionally by some of the same stimuli that modulate its transcrip-tion, meaning that Arc protein expression may increase without an enhancement in Arc mRNA levels [63]. ...
... Arc transcription can be regulated, among others, by NMDA receptors, second messengers, protein kinases, and transcription factors [18,48,63]. Additionally, Arc can be regulated post-transcriptionally by some of the same stimuli that modulate its transcrip-tion, meaning that Arc protein expression may increase without an enhancement in Arc mRNA levels [63]. The strong positive correlations between Arc mRNA and protein levels with those of GluN1 in both the DG and the BLA of control animals after the CPA test might indicate that the activation of NMDA receptors would stimulate Arc transcription and translation in these conditions. ...
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... Forskolin, an adenylyl cyclase activator, can 80 effectively increase the level of cAMP levels and directly activate transcription and translation that is 81 important for the expression and maintenance of protein synthesis-dependent late phase of LTP 82 (Otmakhov 2004). It has also been shown that the translational repression of the IEG Arc is alleviated by 83 application of forskolin, through activation of the cAMP-dependent protein kinase (PKA) pathway 84 (Bloomer 2008). This combination of pharmacological agents, namely 4-AP, bicuculline and forskolin, 85 has been used effectively to induce LTP in cultured hippocampal neurons in the study of Arc dynamics 86 (Wee 2014, Oey 2015, Leung 2019. ...
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