Proteomic profile of differentially expressed proteins in the medial prefrontal cortex after repeated cocaine exposure

Comprehensive Glycomic and Proteomic Analysis of Mouse Striatum and Lateral Hypothalamus Following Repeated Exposures to Cocaine or Methamphetamine

Substance use disorder is a major concern, with few therapeutic options. Heparan sulfate (HS) and chondroitin sulfate (CS) interact with a plethora of growth factors and their receptors and have profound effects on cellular signaling. Thus, targeting these dynamic interactions might represent a potential novel therapeutic modality. In the present study, we performed mass spectrometry-based glycomic and proteomic analysis to understand the effects of cocaine and methamphetamine (METH) on HS, CS, and the proteome of two brain regions critically involved in drug addiction: the lateral hypothalamus and the striatum. We observed that cocaine and METH significantly alter HS and CS abundances as well as sulfate contents and composition. In particular, repeated METH or cocaine treatments reduced CS 4-O-sulfation and increased CS 6-O-sulfation. Since C4S and C6S exercise differential effects on axon growth, regeneration, and plasticity, these changes likely contribute to drug-induced neural plasticity in these brain regions. Notably, we observed that restoring these alterations by increasing CS 4-0 levels in the lateral hypothalamus by adeno-associated virus delivery of an shRNA to arylsulfatase B (N-acetylgalactosamine-4-sulfatase) ameliorated anxiety and prevented the expression of preference for cocaine in a novelty induced conditioned place preference test during cocaine withdrawal. Finally, proteomics analyses revealed a number of aberrant proteins in METH- and cocaine-treated versus saline-treated mice, including myelin proteolipid protein, calcium/calmodulin-dependent protein kinase type II subunit alpha, synapsin-2, tenascin-R, calnexin, annexin A7, hepatoma-derived growth factor, neurocan, and CSPG5, and oxidative phosphorylation among the top perturbed pathway. Taken together, these data support the role of HS, CS, and associated proteins in stimulants abuse and suggest that manipulation of HSPGs can represent a novel therapeutic strategy.

The ubiquitin-proteasome system and learning-dependent synaptic plasticity - A 10 year update

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.

The roles of ubiquitin-proteasome system and regulator of G protein signaling 4 in behavioral sensitization induced by a single morphine exposure

AIMS

Opioid addiction is a major public health issue, yet its underlying mechanism is still unknown. The aim of this study was to explore the roles of ubiquitin-proteasome system (UPS) and regulator of G protein signaling 4 (RGS4) in morphine-induced behavioral sensitization, a well-recognized animal model of opioid addiction.

METHODS

We explored the characteristics of RGS4 protein expression and polyubiquitination in the development of behavioral sensitization induced by a single morphine exposure in rats, and the effect of a selective proteasome inhibitor, lactacystin (LAC), on behavioral sensitization.

RESULTS

Polyubiquitination expression was increased in time-dependent and dose-related fashions during the development of behavioral sensitization, while RGS4 protein expression was not significantly changed during this phase. Stereotaxic administration of LAC into nucleus accumbens (NAc) core inhibited the establishment of behavioral sensitization.

CONCLUSION

UPS in NAc core is positively involved in behavioral sensitization induced by a single morphine exposure in rats. Polyubiquitination was observed during the development phase of behavioral sensitization, while RGS4 protein expression was not significantly changed, indicating that other members of RGS family might be substrate proteins in UPS-mediated behavioral sensitization.

Dynamic Expression Changes in the Transcriptome of the Prefrontal Cortex after Repeated Exposure to Cocaine in Mice

Prefrontal cortex (PFC)-dependent functions, such as executive function, explicit learning, and memory, are negatively affected in cocaine abusers and experimental animal models of cocaine treatment. However, its molecular mechanisms are less understood. In the present study, we performed transcriptome profiling of the dynamic changes in the PFC after repeated cocaine administration in mice. We found 463, 14, and 535 differentially expressed genes (DEGs) at 2 h, 24 h, and 7 days, respectively, after the withdrawal of chronic cocaine treatment. Time-series correlation analysis identified 5 clusters of statistically significant expression patterns. The expression levels of DEGs in Clusters 1 and 5 exhibited a gradual or fluctuant decrease, Cluster 2 exhibited an initial increase followed by a decrease or return to the baseline level, and Clusters 3 and 4 exhibited a fluctuant increase in the expression of DEGs. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that genes related to oxidative phosphorylation, ribosomes, and neurodegenerative disorder were enriched in Cluster 1; genes related to the mitogen activated protein kinase (MAPK), transforming growth factor (TGF)-β, insulin signaling, and circadian pathways were enriched in Cluster 2; genes related to plasticity-related pathways were enriched in Clusters 3 and 4; and genes related to the proteasome were enriched in Cluster 5. Our results suggest that maladaptive neural plasticity associated with psychostimulant dependence may be an ongoing degenerative process with dynamic changes in the gene network at different stages of withdrawal. Furthermore, it could be helpful to develop new therapeutic approaches according to different periods of abstinence.

The role of the ubiquitin proteasome system in the memory process

Quite intuitive is the notion that memory formation and consolidation is orchestrated by protein synthesis because of the synaptic plasticity necessary for those processes. Nevertheless, recent advances have begun accumulating evidences of a high requirement for protein degradation on the molecular mechanisms of the memory process in the mammalian brain. Because degradation determines protein half-life, degradation has been increasingly recognized as an important intracellular regulatory mechanism. The proteasome is the main player in the degradation of intracellular proteins. Proteasomal substrates are mainly degraded after a post-translational modification by a poly-ubiquitin chain. Latter process, namely poly-ubiquitination, is highly regulated at the step of the ubiquitin molecule transferring to the protein substrate mediated by a set of proteins whose genes represent almost 2% of the human genome. Understanding the role of polyubiquitin-mediated protein degradation has challenging researchers in many fields of investigation as a new source of targets for therapeutic intervention, e.g. E3 ligases that transfer ubiquitin moieties to the substrate. The goal of present work was to uncover mechanisms underlying memory processes regarding the role of the ubiquitin-proteasome system (UPS). For that purpose, preceded of a short review on UPS and memory processes a top-down systems biology approach was applied to establish central proteins involved in memory formation and consolidation highlighting their cross-talking with the UPS. According to that approach, the pattern of expression of several elements of the UPS were found overexpressed in regions of the brain involved in processing cortical inputs.

Cocaine and ethanol target 26S proteasome activity and gene expression in neuroblastoma cells

BACKGROUND

Ethanol and cocaine are widely abused drugs triggering long-lasting changes in neuronal circuits and synaptic transmission through the regulation of enzyme activity and gene expression. Compelling evidence indicates that the ubiquitin-proteasome system plays a role in the molecular changes induced by addictive substances, impacting on several mechanisms implicated in abuse. The goal of these studies was to evaluate the effects of cocaine or ethanol on proteasome activity in neuroblastoma cells. Moreover, the gene expression of specific subunits was assessed.

METHODS

Chymotrypsin-like activity was measured after 2 h, 24 h, and 48 h exposure to 5 μM cocaine or 40 mM ethanol. Proteasome subunit transcripts were evaluated by qPCR at the same time-points.

RESULTS

Treatments modified proteasome function in opposite directions, since cocaine increased and ethanol reduced chymotrypsin-like activity. Interestingly, we observed gene expression alterations induced by these drugs. In the core particle, the β1 and α5 subunits were mainly up-regulated by cocaine, whereas α6 transcripts were mostly decreased. β2 and β5 did not change. Similarly, ethanol exposure generally increased β1 and α5 mRNAs. Moreover, the β2 subunit was significantly up-regulated by ethanol only. The β5 and α6 subunits were not altered. In the regulatory particle, Rpt3 was increased by cocaine exposure, whereas it was reduced by ethanol. No significant Rpn9 alterations were observed.

CONCLUSIONS

These findings support the notion that addictive substances regulate proteasome function, contributing to the dysregulations related to drug abuse since the availability of adequate subunit amounts is necessary for proper complex assembly and function.

Roles of the ubiquitin proteasome system in the effects of drugs of abuse

Because of its ability to regulate the abundance of selected proteins the ubiquitin proteasome system (UPS) plays an important role in neuronal and synaptic plasticity. As a result various stages of learning and memory depend on UPS activity. Drug addiction, another phenomenon that relies on neuroplasticity, shares molecular substrates with memory processes. However, the necessity of proteasome-dependent protein degradation for the development of addiction has been poorly studied. Here we first review evidences from the literature that drugs of abuse regulate the expression and activity of the UPS system in the brain. We then provide a list of proteins which have been shown to be targeted to the proteasome following drug treatment and could thus be involved in neuronal adaptations underlying behaviors associated with drug use and abuse. Finally we describe the few studies that addressed the need for UPS-dependent protein degradation in animal models of addiction-related behaviors.

Alzheimer's and Parkinson's diseases: an environmental proteomic point of view

Alzheimer's and Parkinson's diseases are severe neurodegenerative conditions triggered by complex biochemical routes. Many groups are currently pursuing the search for valuable biomarkers to either perform early diagnostic or to follow the disease's progress. Several studies have reported relevant findings regarding environmental issues and the progression of such diseases. Here the etiology and mechanisms of these diseases are briefly reviewed. Approaches that might reveal candidate biomarkers and environmental stressors associated to the diseases were analyzed under a proteomic perspective. This article is part of a Special Issue entitled: Environmental and structural proteomics.

Biomarkers for the development of new medications for cocaine dependence

There has been significant progress in personalized drug development. In large part, this has taken place in the oncology field and been due to the ability of researchers/clinicians to discover and develop novel drug development tools (DDTs), such as biomarkers. In cancer treatment research, biomarkers have permitted a more accurate pathophysiological characterization of an individual patient, and have enabled practitioners to target mechanistically the right drug, to the right patient, at the right time. Similar to cancer, patients with substance use disorders (SUDs) present clinically with heterogeneous symptomatology and respond variably to therapeutic interventions. If comparable biomarkers could be identified and developed for SUDs, significant diagnostic and therapeutic advances could be made. In this review, we highlight current opportunities and difficulties pertaining to the identification and development of biomarkers for SUDs. We focus on cocaine dependence as an example. Putative diagnostic, pharmacodynamic (PD), and predictive biomarkers for cocaine dependence are discussed across a range of methodological approaches. A possible cocaine-dependent clinical outcome assessment (COA)--another type of defined DDT--is also discussed. At present, biomarkers for cocaine dependence are in their infancy. Much additional research will be needed to identify, validate, and qualify these putative tools prior to their potential use for medications development and/or application to clinical practice. However, with a large unmet medical need and an estimated market size of several hundred million dollars per year, if developed, biomarkers for cocaine dependence will hold tremendous value to both industry and public health.