Real-Time Imaging Reveals Properties of Glutamate-Induced Arc/Arg 3.1 Translation in Neuronal Dendrites

Abstract

Summary The immediate early gene Arc (also Arg3.1) produces rapid changes in synaptic properties that are linked to de novo translation. Here we develop a novel translation reporter that exploits the rapid maturation and “flash” kinetics of Gaussia luciferase (Gluc) to visualize Arc translation. Following glutamate stimulation, discrete Arc-Gluc bioluminescent flashes representing sites of de novo translation are detected within 15 s at distributed sites in dendrites, but not spines. Flashes are episodic, lasting ∼20 s, and may be unitary or repeated at ~minute intervals at the same sites. Analysis of flash amplitudes suggests they represent the quantal product of one or more polyribosomes, while inter-flash intervals appear random, suggesting they arise from a stochastic process. Surprisingly, glutamate-induced translation is dependent on Arc open reading frame. Combined observations support a model in which stalled ribosomes are reactivated to rapidly generate Arc protein.

Emotional Modulation of Learning and Memory: Pharmacological Implications

“…These findings suggest that dendritically localized synaptic plasticity-related mRNAs like Arc are markers of where synaptic plasticity is occurring and that BLA activation is a regulator of when it occurs. Na et al (2016) recently found that glutamate induced rapid translation of ARC in hippocampal dendrites and that reactivation of stalled polyribosomes mediated this effect. Figure 3 provides a schematic diagram for how the BLA influences ARC expression in regions, such as the hippocampus, important for processing declarative memory information.…”

The Growing Toolbox for Protein Synthesis Studies

“…Alternatively, synthetic reporters harboring the rapidly maturing Gaussia luciferase (Gluc) can be used to monitor protein synthesis in real time with sub-cellular resolution [17]. Gluc requires only the substrate coelenterazine (CTZ), and no other cofactors ( e.g.…”

“…In general, these techniques do rely on the delivery of chemical reagents, and in many cases require fixation before measurement as well. Nonetheless, they can reveal the variations in translatability among cell populations [7,12,13] and animal tissue [12], and of local translation [9] such as in the dendrites of neurons [10,14–17]. …”

Homeostatic scaling is driven by a translation-dependent degradation axis that recruits miRISC remodeling

“…Hebbian plasticity paradigms triggers homeostatic scaling in neurons as a compensatory mechanism (Vitureira & Goda, 2013); these two opposing forms of plasticity must involve a combination of overlapping and distinct molecular players. Our data demonstrates the requirement of a rapamycin-sensitive, MOV10 degradation-dependent Arc translation in homeostatic scaling that is distinct from the rapamycin-insensitive dendritic translation of Arc ocurring during Hebbian plasticity (Na et al, 2016). We speculate that homeostatic and Hebbian plasticity engages distinct signalling pathways that converge at miRISC remodelling.…”