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Memory consolidation of the spatial learning task required only one wave of protein degradation. (A) The behavioral procedure used for consolidation. (B) Mean latency (s) to find the platform during the training phase of the spatial water maze task. (C) Immediately or (D) 3 h after the last training session, the mice received injections of LAC or DMSO. (C and D) Number of annuli crossings during the 60-s probe trial. LAC injection in the CA3 region just after acquisition impaired spatial performances and had no effect if injections were performed at 3 h. *P < 0.05, **P < 0.01, ***P < 0.001 vs. target quadrant. ##P <0.01, target quadrant DMSO vs. LAC group.
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The formation of long-term memory requires protein synthesis, particularly during initial memory consolidation. This process also seems to be dependant upon protein degradation, particularly degradation by the ubiquitin-proteasome system. The aim of this study was to investigate the temporal requirement of protein synthesis and degradation during t...
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Context 1
... investigate the role of protein degradation during memory consolidation, animals were injected with LAC either immediately or 3 h after acquisition (Fig. 4A). A repeated-measures anova on latency to find the platform during training (Fig. 4B) Tukey post hoc comparisons revealed that control mice swam more often at the target annulus than at any of the other three equivalent annuli, while LAC-injected animals did not show any such quadrant preference. For the animals that were injected 3 h ...
Context 2
... investigate the role of protein degradation during memory consolidation, animals were injected with LAC either immediately or 3 h after acquisition (Fig. 4A). A repeated-measures anova on latency to find the platform during training (Fig. 4B) Tukey post hoc comparisons revealed that control mice swam more often at the target annulus than at any of the other three equivalent annuli, while LAC-injected animals did not show any such quadrant preference. For the animals that were injected 3 h post-acquisition, animals in both the control and LAC groups swam more often in the ...
Context 3
... that control mice swam more often at the target annulus than at any of the other three equivalent annuli, while LAC-injected animals did not show any such quadrant preference. For the animals that were injected 3 h post-acquisition, animals in both the control and LAC groups swam more often in the target annulus than in the other three annuli (Fig. 4D). Anova revealed that animals in both groups demonstrated a significant quadrant effect [F(3,64) = 20.801, P < 0.001], no treatment effect [F(1,64) = 0.125, P = 0.815], and no quadrant · treatment inter- action effect [F(3,64) = 0.569, P = 0.861]. These results demonstrate that performance was not impaired by LAC injected 3 h post- ...
Similar publications
Numerous studies have indicated that the consolidation of contextual fear memories supported by an aversive outcome like footshock requires de novo protein synthesis as well as protein degradation mediated by the ubiquitin-proteasome system (UPS). Context memory formed in the absence of an aversive stimulus by simple exposure to a novel environment...
Long-term memory formation depends on protein and mRNA synthesis that subserves synaptic reorganization. The removal of pre-existing inhibitory proteins by the ubiquitin-proteasome system (UPS) is proposed as a crucial step to support these modifications. The activation of the constitutive transcription factor nuclear factor kappaB (NF-kappaB) depe...
Citations
... Protein degradation by the proteasome mediates synaptic plasticity and memory processes. Inhibiting brain proteasome activity impairs synaptogenesis 3 , the maintenance of long-term potentiation 4 , and both the formation and extinction of memories in mice [5][6][7] . Evidence indicates that neuronal activity promotes calcium-calmodulin-dependent kinase IIα (CaMKIIα)-mediated recruitment and activity of proteasomes at synapses, and that this is necessary for long-lasting changes in synapse structure and strength [8][9][10] . ...
Background
The proteasome plays key roles in neuronal function by regulating protein turnover, quality control, and elimination of oxidized and misfolded proteins. Recent evidence indicates that proteasome activity is required for synaptic plasticity and memory, and may be altered in Alzheimer’s disease (AD).
Method
Here, we investigate proteasome function and localization at synapses in AD post‐mortem brain tissue and in experimental models of AD by using western blotting, immunocytochemistry and proteasome activity assay. We also evaluated core AD‐related features upon proteasome inhibition by using DCFDA measurement, phaloidin staining, SUnSET and mice memory tasks.
Result
We found a marked increase in ubiquitinylated proteins in post‐mortem AD hippocampi compared to controls. Using human ex vivo adult cortical tissue, primary neuronal cultures, isolated synaptosomes and in vivo experiments in mice, we show that amyloid‐b oligomers (AbOs) inhibit synaptic proteasome activity and trigger a reduction in synaptic proteasome content. We further show proteasome inhibition specifically in hippocampal synaptic fractions derived from APPswePS1DE9 mice. Treatment with the proteasome inhibitor, lactacystin, induces reactive oxygen species formation and loss of dendritic spines in hippocampal neurons, inhibits hippocampal mRNA translation, and causes memory impairment in mice.
Conclusion
These findings demonstrate that synaptic proteasome activity is inhibited in post‐mortem AD brain tissue and in experimental models of AD. Results further show that proteasome inhibition is associated with spine loss and memory impairment in mice, suggesting that proteasome inhibition may contribute to synaptic and memory deficits in AD.
... Protein degradation by the proteasome mediates synaptic plasticity and memory processes. Inhibiting brain proteasome activity impairs synaptogenesis 3 , the maintenance of long-term potentiation 4 , and both the formation and extinction of memories in mice [5][6][7] . Evidence indicates that neuronal activity promotes calcium-calmodulin-dependent kinase IIα (CaMKIIα)-mediated recruitment and activity of proteasomes at synapses, and that this is necessary for long-lasting changes in synapse structure and strength [8][9][10] . ...
The proteasome plays key roles in synaptic plasticity and memory by regulating protein turnover, quality control, and elimination of oxidized/misfolded proteins. Here, we investigate proteasome function and localization at synapses in Alzheimer's disease (AD) post-mortem brain tissue and in experimental models. We found a marked increase in ubiquitinylated proteins in post-mortem AD hippocampi compared to controls. Using several experimental models, we show that amyloid-β oligomers (AβOs) inhibit synaptic proteasome activity and trigger a reduction in synaptic proteasome content. We further show proteasome inhibition specifically in hippocampal synaptic fractions derived from APPswePS1ΔE9 mice. Reduced synaptic proteasome activity instigated by AβOs is corrected by treatment with rolipram, a phosphodiesterase-4 inhibitor, in mice. Results further show that dynein inhibition blocks AβO-induced reduction in dendritic proteasome content in hippocampal neurons. Finally, proteasome inhibition induces AD-like pathological features, including reactive oxygen species and dendritic spine loss in hippocampal neurons, inhibition of hippocampal mRNA translation, and memory impairment in mice. Results suggest that proteasome inhibition may contribute to synaptic and memory deficits in AD.
... However, no further studies, to date, have been done to determine the role of protein degradation in the female PFC during trace fear conditioning. Similarly, when the proteasome inhibitor lactacystin, a precursor to β-lac, was injected into the hippocampal region, male animals had impaired memory for the Morris water maze and inhibitory avoidance tasks (Artinian et al., 2008;Lopez-Salon et al., 2001), though again this has not been tested in females. Interestingly, proteasome inhibition in the insular cortex, but not the amygdala, prevented long-term memory consolidation for a conditioned taste aversion task in male rodents (Rodriguez-Ortiz et al., 2011). ...
... This has led to the widely accepted theory that protein degradation regulates the destabilization of memories following retrieval. However, it should be noted that some studies have reported impairments in memory following post-retrieval inhibition of proteasome function (Artinian et al., 2008). Furthermore, all of the studies on ubiquitin-proteasome signaling in reconsolidation, to date, have been done with only male rodents, leaving a number of questions about whether protein degradation also regulates the destabilization of memory in females. ...
Over 25 years ago, a seminal paper demonstrated that the ubiquitin-proteasome system (UPS) was involved in activity-dependent synaptic plasticity. Interest in this topic began to expand around 2008 following another seminal paper showing that UPS-mediated protein degradation controlled the "destabilization" of memories following retrieval, though we remained with only a basic understanding of how the UPS regulated activity- and learning-dependent synaptic plasticity. However, over the last 10 years there has been an explosion of papers on this topic that has significantly changed our understanding of how ubiquitin-proteasome signaling regulates synaptic plasticity and memory formation. Importantly, we now know that the UPS controls much more than protein degradation, is involved in plasticity underlying drugs of abuse and that there are significant sex differences in how ubiquitin-proteasome signaling is used for memory storage processes. Here, we aim to provide a critical 10-year update on the role of ubiquitin-proteasome signaling in synaptic plasticity and memory formation, including updated cellular models of how ubiquitin-proteasome activity could be regulating learning-dependent synaptic plasticity in the brain.
... In a similar test of spatial learning and memory, mice were trained in a Morris water maze and then received a proteasome inhibitor after the final trial. The drug reduced immediate crossing of the target location in mice, but not 3 h after the trial (Artinian et al., 2008). These data suggest that the proteasome is involved in the formation of spatial and contextual memory. ...
... Treatment with proteasome inhibitors appears to impair memory consolidation and retrieval. Surprisingly, it also appears to be required for memory extinction and proteasome impairment in animal models (Lopez-Salon et al., 2001;Artinian et al., 2008;Lee, 2008;Lee et al., 2008;Rodriguez-Ortiz et al., 2011;Felsenberg et al., 2012). ...
The proteasome is a large multi-subunit protease responsible for the degradation and removal of oxidized, misfolded, and polyubiquitinated proteins. The proteasome plays critical roles in nervous system processes. This includes maintenance of cellular homeostasis in neurons. It also includes roles in long-term potentiation via modulation of CREB signaling. The proteasome also possesses roles in promoting dendritic spine growth driven by proteasome localization to the dendritic spines in an NMDA/CaMKIIα dependent manner. Proteasome inhibition experiments in varied organisms has been shown to impact memory, consolidation, recollection and extinction. The proteasome has been further shown to impact circadian rhythm through modulation of a range of ‘clock’ genes, and glial function. Proteasome function is impaired as a consequence both of aging and neurodegenerative diseases. Many studies have demonstrated an impairment in 26S proteasome function in the brain and other tissues as a consequence of age, driven by a disassembly of 26S proteasome in favor of 20S proteasome. Some studies also show proteasome augmentation to correct age-related deficits. In amyotrophic lateral sclerosis Alzheimer’s, Parkinson’s and Huntington’s disease proteasome function is impaired through distinct mechanisms with impacts on disease susceptibility and progression. Age and neurodegenerative-related deficits in the function of the constitutive proteasome are often also accompanied by an increase in an alternative form of proteasome called the immunoproteasome. This article discusses the critical role of the proteasome in the nervous system. We then describe how proteasome dysfunction contributes to brain aging and neurodegenerative disease.
... To date, protein degradation is increased in several brain regions following behavioral training, including the amygdala, hippocampus, prefrontal cortex, and insular cortex (Lopez-Salon et al. 2001;Jarome et al. 2011;Reis et al. 2013;Orsi et al. 2019;Beamish et al. 2022). Additionally, inhibition of functional proteasome activity has been shown to impair the consolidation of memories for a wide variety of aversive and nonaversive tasks, including auditory and contextual fear conditioning, trace fear conditioning, inhibitory avoidance, Morris water maze, conditioned taste aversion, object recognition, and object location tasks (Lopez-Salon et al. 2001;Artinian et al. 2008;Lee et al. 2008;Choi et al. 2010;Jarome et al. 2011;Rodriguez-Ortiz et al. 2011;Reis et al. 2013;Figueiredo et al. 2015;Furini et al. 2015;Cullen et al. 2017;Devulapalli et al. 2019). Furthermore, this need for proteasome-dependent protein degradation is shared across sexes (Devulapalli et al. 2021), although this does vary based on the brain region examined . ...
Strong evidence has implicated proteasome-mediated protein degradation in the memory consolidation process. However, due to the use of pharmacological approaches, the cell type specificity of this remains unknown. Here, we used neuron-specific and novel astrocyte-specific CRISPR–dCas9–KRAB–MECP2 plasmids to inhibit protein degradation in a cell type-specific manner in the amygdala of male rats. We found that while inhibition of neuronal, but not astrocytic, protein degradation impaired performance during the training session, both resulted in impaired contextual fear memory retention. Together, these data provide the first evidence of a cell type-specific role for protein degradation in the memory consolidation process.
... Furthermore, neurobiological studies reveal that intracellular protein degradation mechanisms make the memory susceptible to a potential change, thus supporting this plastic aspect of the reconsolidation process [128][129][130][131][132][133][134]. Additionally, recent preclinical studies have shown that PNNs have a role in addiction memory neuroplasticity and are found in the human brain regions responsible for emotional processing, autobiographical memory, MEAMs, and the sensation of craving (Table 1) [118,119,135,136]. ...
... An experience is acquired (acquisition) and it becomes stronger over time (consolidation). When these memories are retrieved or recalled, they become labile, and this is related to specific intracellular protein degradation mechanisms-ubiquitin-proteasome system [128,130,131,133]. At this stage, memories are susceptible to being strengthened, weakened, or updated by pharmacological or non-pharmacological treatments for certain periods of time that are estimated from minutes to hours [13,133]. ...
... It has been suggested that the characteristics of autobiographical memories can be taken as a frame of reference to study addiction memories because they are both related to personal experiences that, in the case of addiction memories in humans, are related to the individual's history of drug use [146]. The recall of autobiographical memories is a labile process [125] and the reconsolidation stage depends on specific intracellular protein degradation mechanisms (the ubiquitin/proteasome-dependent protein degradation pathways) that make the memory susceptible to a possible modification [128][129][130][131][132][133][134]. Authors suggested that, at the reconsolidation stage, those memories can be strengthened, weakened, or updated by pharmacological or non-pharmacological treatments for a period of time that is estimated from minutes to hours [13,133]. ...
Recent findings indicate that Music Therapy (MT) and Music-Based Interventions (MBIs) may reduce craving symptoms in people with Substance Use Disorders (SUD). However, MT/MBIs can lead SUD clients to recall memories associated with their drug history and the corresponding strong emotions (addiction memories). Craving is a central component of SUD, possibly linked to relapse and triggered by several factors such as the recall of memories associated with the drug experience. Therefore, to address the topic of what elements can account for an improvement in craving symptoms after MT/MBIs, we conducted a narrative review that (1) describes the brain correlates of emotionally salient autobiographical memories evoked by music, (2) outlines neuroimaging and neurophysiological studies suggesting how the experience of craving may encompass the recall of emotionally filled moments, and (3) points out the role of perineuronal nets (PNNs) in addiction memory neuroplasticity. We highlight how autobiographical memory retrieval, music-evoked autobiographical memories, and craving share similar neural activations with PNNs which represent a causal element in the processing of addiction memory. We finally conclude by considering how the neuroplastic characteristics of addiction memory might represent the ground to update and/or recalibrate, within the therapy, the emotional content related to the recall.
... Moreover, the persistence of fear memory requires both eIF4E-eIF4G interaction and S6K1 activation. mTORC1 plays an essential role in reconsolidation of drug-related memories as shown in studies using conditioned place preference (Lin et al., 2014) or self-administration models (Barak et al., 2013;Zhang et al., 2021). However, whether eIF4E-eIF4G interactions and S6K1, two mTORC1 downstream targets, are involved in reconsolidation of cocaine contextual memories remains unknown. ...
... Arc has been implicated in synaptic plasticity (Plath et al., 2006;Rial Verde et al., 2006), memory consolidation (Plath et al., 2006;Ploski et al., 2008), and reconsolidation of Pavlovian fear memory (Maddox and Schafe, 2011;Chia and Otto, 2013). Arc is regulated by drug-related memories including alcohol (Barak et al., 2013), cocaine (Hearing et al., 2008a;Hearing et al., 2008b;Alaghband et al., 2014), and morphine (Lv et al., 2015). The expression of Arc mRNA can be used as a marker for neuronal plasticity. ...
... However, accumulating evidence suggests that memory reconsolidation process is more complicated than initially thought. A growing body of literature suggest that both protein degradation and synthesis are required for reconsolidation of spatial and fear memory (Artinian et al., 2008;Lee et al., 2008;Jarome et al., 2011). For example, inhibition of protein degradation with the inhibitor lactacystin immediately, but not 3 h, after memory reactivation impairs the reconsolidation of spatial memory (Artinian et al., 2008). ...
Mechanistic target of rapamycin (mTOR) C1 and its downstream effectors have been implicated in synaptic plasticity and memory. Our prior work demonstrated that reactivation of cocaine memory engages a signaling pathway consisting of Akt, glycogen synthase kinase-3β (GSK3β), and mTORC1. The present study sought to identify other components of mTORC1 signaling involved in the reconsolidation of cocaine contextual memory, including eukaryotic translation initiation factor 4E (eIF4E)-eIF4G interactions, p70 S6 kinase polypeptide 1 (p70S6K, S6K1) activity, and activity-regulated cytoskeleton ( Arc ) expression. Cocaine contextual memory was established in adult CD-1 mice using conditioned place preference. After cocaine place preference was established, mice were briefly re-exposed to the cocaine-paired context to reactivate the cocaine memory and brains examined. Western blot analysis showed that phosphorylation of the mTORC1 target, p70S6K, in nucleus accumbens and hippocampus was enhanced 60 min following reactivation of cocaine memories. Inhibition of mTORC1 with systemic administration of rapamycin or inhibition of p70S6K with systemic PF-4708671 after reactivation of cocaine contextual memory abolished the established cocaine place preference. Immunoprecipitation assays showed that reactivation of cocaine memory did not affect eIF4E–eIF4G interactions in nucleus accumbens or hippocampus. Levels of Arc mRNA were significantly elevated 60 and 120 min after cocaine memory reactivation and returned to baseline 24 h later. These findings demonstrate that mTORC1 and p70S6K are required for reconsolidation of cocaine contextual memory.
... Of these, learning-induced changes in UPS activity have been most extensively documented in response to contextual fear learning, which increases K48 polyubiquitination, Rpt6 phosphorylation, and 20S proteasome activity in the amygdala of male rats in a manner dependent on activation of NMDARs and CaMKII, but not PKA, activity (Jarome et al. 2011. Although proteasome activity is also required for the consolidation of spatial and object recognition memories in male rodents (Artinian et al. 2008;Choi et al. 2010;Figueiredo et al. 2015), it is unclear whether nonaversive tasks, such as object placement and object recognition, activate the same UPS signaling mechanisms and proteasome subunits as aversive learning tasks. ...
... Moreover, the mechanisms underlying the observed sex-, brain region-, and compartment-specific differences remain unclear at the present time, as is the relative importance of UPS activity in mediating object recognition and object placement memory consolidation in females and males. Although previous reports demonstrate that proteasome activity in the hippocampus is required for consolidation and reconsolidation of spatial and object recognition memories in male rodents (Artinian et al. 2008;Choi et al. 2010;Figueiredo et al. 2015), it is unknown whether females similarly require proteasome activity for the successful consolidation of object memories. Thus, future work should assess whether the observed brain region-and compartment-specific alterations in UPS activity have functional consequences for the formation of object memories in females. ...
The ubiquitin proteasome system (UPS) is a primary mechanism through which proteins are degraded in cells. UPS activity in the dorsal hippocampus (DH) is necessary for multiple types of memory, including object memory, in male rodents. However, sex differences in DH UPS activation after fear conditioning suggest that other forms of learning may also differentially regulate DH UPS activity in males and females. Here, we examined markers of UPS activity in the synaptic and cytoplasmic fractions of DH and medial prefrontal cortex (mPFC) tissue collected 1 h following object training. In males, training increased phosphorylation of proteasomal subunit Rpt6, 20S proteasome activity, and the amount of PSD-95 in the DH synaptic fraction, as well as proteasome activity in the mPFC synaptic fraction. In females, training did not affect measures of UPS or synaptic activity in the DH synaptic fraction or in either mPFC fraction but increased Rpt6 phosphorylation in the DH cytoplasmic fraction. Overall, training-induced UPS activity was greater in males than in females, greater in the DH than in the mPFC, and greater in synaptic fractions than in cytosol. These data suggest that object training drives sex-specific alterations in UPS activity across brain regions and subcellular compartments important for memory.
... In experiment 2, we used the same fear conditioning protocol, but this time SCH23390 was delivered through intrahippocampal infusion (0.5 µg/side, 0.35 µL/side); the control group received infusions of the same volume of saline. For this purpose, 2 wk prior to conditioning, we implanted guide cannulas aimed at CA1 (as described in Artinian et al. 2008). Infusion site locations were verified by infusing Chicago blue (2% in 0.5 M acetate) 3-5 d after the last behavioral session, which showed that all implanted mice had their infusions correctly centered in the hippocampus (n = 14 per group) (Fig. 1C). ...
Dopamine participates in encoding memories and could either encode rewarding/aversive value of unconditioned stimuli or act as a novelty signal triggering contextual learning. Here we show that intraperitoneal injection of the dopamine D1/5R antagonist SCH23390 impairs contextual fear conditioning and tone-shock association, while intrahippocampal injection only impairs contextual fear conditioning. By using the context pre-exposure facilitation effect test, we show that SCH23390 is able to block the encoding of the context during the pre-exposure phase. Thus, we provide additional evidence that dopamine is involved in encoding conjunctive representations of new contexts.
... Once one ubiquitin binds to a target protein, each subsequent ubiquitin then attaches to the one before it, forming a polyubiquitin chain that allows some, but not all, target substrates to be destroyed by the 26 S proteasome complex [6,7]. While initial studies focused on the role of ubiquitin-proteasome mediated protein degradation in activity-dependent synaptic plasticity, recent evidence has strongly implicated this process in memory formation in the brain [8][9][10][11][12][13][14][15][16][17][18]. Of note, we recently found that while both male and female rats need degradation-dependent and independent UPS signaling to regulate fear memory formation in the amygdala [19,20], they differ significantly in the protein targets of ubiquitin signaling following learning [21]. ...
Strong evidence has implicated ubiquitin signaling in the process of fear memory formation. While less abundant than ubiquitination, evidence suggests that protein SUMOylation may also be involved in fear memory formation in neurons. However, the importance of amygdala protein SUMOylation in fear memory formation has never been directly examined. Furthermore, while recent evidence indicates that males and females differ significantly in the requirement for ubiquitin signaling during fear memory formation, whether sex differences also exist in the importance of protein SUMOylation to this process remains unknown. Here we found that males and females differ in the requirement for protein SUMOylation in the amygdala during fear memory formation. Western blot analysis revealed that while females had higher resting levels of SUMOylation, both sexes showed global increases following fear conditioning. However, SUMOylation-specific proteomic analysis revealed that only females have increased targeting of individual proteins by SUMOylation following fear conditioning, some of which were heat shock proteins. This suggests that protein SUMOylation is more robustly engaged in the amygdala of females following fear conditioning. In vivo siRNA mediated knockdown of Ube2i, the coding gene for the essential E2 ligase for SUMOylation conjugation, in the amygdala impaired fear memory in males without any effect in females. Importantly, higher siRNA concentrations than what was needed to impair memory in males reduced Ube2i levels in the amygdala of females but resulted in an increase in SUMOylation levels, suggesting a compensatory effect in females that was not observed in males. Collectively, these data reveal a novel, sex-specific role for protein SUMOylation in the amygdala during fear memory formation and expand our understanding of how ubiquitin-like signaling regulates memory formation.
