Proteomic analysis reveals differentially expressed proteins in the rat frontal cortex after methamphetamine treatment

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 (LH) and the striatum (ST). 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 LH by adeno-associated virus (AAV) delivery of an shRNA to Arylsulfatase B (N-acetylgalactosamine-4-sulfatase, ARSB) 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 vs. saline-treated mice, including MYPR, KCC2A, SYN2, TENR, CALX, ANXA7, HDGF, NCAN, 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.

A comprehensive study to delineate the role of an extracellular vesicle-associated microRNA-29a in chronic methamphetamine use disorder

Extracellular vesicles (EVs), which express a repertoire of cargo molecules (cf. proteins, microRNA, lipids, etc.), have been garnering a prominent role in the modulation of several cellular processes. Here, using both non-human primate and rodent model systems, we provide evidence that brain-derived EV (BDE) miRNA, miR-29a-3p (mir-29a), is significantly increased during chronic methamphetamine (MA) exposure. Further, miR-29a levels show significant increase both with drug-seeking and reinstatement in a rat MA self-administration model. We also show that EV-associated miR-29a is enriched in EV pool comprising of small EVs and exomeres and further plays a critical role in MA-induced inflammation and synaptodendritic damage. Furthermore, treatment with the anti-inflammatory drug ibudilast (AV411), which is known to reduce MA relapse, decreased the expression of miR-29a and subsequently attenuated inflammation and rescued synaptodendritic injury. Finally, using plasma from MUD subjects, we provide translational evidence that EV-miR29a could potentially serve as a biomarker to detect neuronal damage in humans diagnosed with MA use disorder (MUD). In summary, our work suggests that EV-associated miR-29a-3p plays a crucial role in MUD and might be used as a potential blood-based biomarker for detecting chronic inflammation and synaptic damage.

Proteomic and Metabolomic Characterization of Human Neurovascular Unit Cells in Response to Methamphetamine

The functional state of the neurovascular unit (NVU), composed of the blood-brain barrier and the perivasculature that forms a dynamic interface between the blood and the central nervous system (CNS), plays a central role in the control of brain homeostasis and is strongly affected by CNS drugs. Human primary brain microvascular endothelium, astrocyte, pericyte, and neural cell cultures are often used to study NVU barrier functions as well as drug transport and efficacy; however, the proteomic and metabolomic responses of these different cell types are not well characterized. Culturing each cell type separately, using deep coverage proteomic analysis and characterization of the secreted metabolome, as well as measurements of mitochondrial activity, the responses of these cells under baseline conditions and when exposed to the NVU-impairing stimulant methamphetamine (Meth) are analyzed. These studies define the previously unknown metabolic and proteomic profiles of human brain pericytes and lead to improved characterization of the phenotype of each of the NVU cell types as well as cell-specific metabolic and proteomic responses to Meth.

A Mutation in Hnrnph1 That Decreases Methamphetamine-Induced Reinforcement, Reward, and Dopamine Release and Increases Synaptosomal hnRNP H and Mitochondrial Proteins

Individual variation in the addiction liability of amphetamines has a heritable genetic component. We previously identified Hnrnph1 (heterogeneous nuclear ribonucleoprotein H1) as a quantitative trait gene underlying decreased methamphetamine-induced locomotor activity in mice. Here, we showed that mice (both females and males) with a heterozygous mutation in the first coding exon of Hnrnph1 (H1^+/-) showed reduced methamphetamine reinforcement and intake and dose-dependent changes in methamphetamine reward as measured via conditioned place preference. Furthermore, H1^+/- mice showed a robust decrease in methamphetamine-induced dopamine release in the NAc with no change in baseline extracellular dopamine, striatal whole-tissue dopamine, dopamine transporter protein, dopamine uptake, or striatal methamphetamine and amphetamine metabolite levels. Immunohistochemical and immunoblot staining of midbrain dopaminergic neurons and their forebrain projections for TH did not reveal any major changes in staining intensity, cell number, or forebrain puncta counts. Surprisingly, there was a twofold increase in hnRNP H protein in the striatal synaptosome of H1^+/- mice with no change in whole-tissue levels. To gain insight into the mechanisms linking increased synaptic hnRNP H with decreased methamphetamine-induced dopamine release and behaviors, synaptosomal proteomic analysis identified an increased baseline abundance of several mitochondrial complex I and V proteins that rapidly decreased at 30 min after methamphetamine administration in H1^+/- mice. In contrast, the much lower level of basal synaptosomal mitochondrial proteins in WT mice showed a rapid increase. We conclude that H1^+/- decreases methamphetamine-induced dopamine release, reward, and reinforcement and induces dynamic changes in basal and methamphetamine-induced synaptic mitochondrial function.SIGNIFICANCE STATEMENT Methamphetamine dependence is a significant public health concern with no FDA-approved treatment. We discovered a role for the RNA binding protein hnRNP H in methamphetamine reward and reinforcement. Hnrnph1 mutation also blunted methamphetamine-induced dopamine release in the NAc, a key neurochemical event contributing to methamphetamine addiction liability. Finally, Hnrnph1 mutants showed a marked increase in basal level of synaptosomal hnRNP H and mitochondrial proteins that decreased in response to methamphetamine, whereas WT mice showed a methamphetamine-induced increase in synaptosomal mitochondrial proteins. Thus, we identified a potential role for hnRNP H in basal and dynamic mitochondrial function that informs methamphetamine-induced cellular adaptations associated with reduced addiction liability.

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.

Proteomics Analysis of Dorsal Striatum Reveals Changes in Synaptosomal Proteins following Methamphetamine Self-Administration in Rats

Methamphetamine is a widely abused, highly addictive drug. Regulation of synaptic proteins within the brain’s reward pathway modulates addiction behaviours, the progression of drug addiction and long-term changes in brain structure and function that result from drug use. Therefore, using large scale proteomics studies we aim to identify global protein expression changes within the dorsal striatum, a key brain region involved in the modulation of addiction. We performed LC-MS/MS analyses on rat striatal synaptosomes following 30 days of methamphetamine self-administration (2 hours/day) and 14 days abstinence. We identified a total of 84 differentially-expressed proteins with known roles in neuroprotection, neuroplasticity, cell cytoskeleton, energy regulation and synaptic vesicles. We identify significant expression changes in stress-induced phosphoprotein and tubulin polymerisation-promoting protein, which have not previously been associated with addiction. In addition, we confirm the role of amphiphysin and phosphatidylethanolamine binding protein in addiction. This approach has provided new insight into the effects of methamphetamine self-administration on synaptic protein expression in a key brain region associated with addiction, showing a large set of differentially-expressed proteins that persist into abstinence. The mass spectrometry proteomics data are available via ProteomeXchange with identifier PXD001443.

Chronic methamphetamine treatment reduces the expression of synaptic plasticity genes and changes their DNA methylation status in the mouse brain

Methamphetamine (METH) is a highly addictive psychostimulant that may cause long-lasting synaptic dysfunction and abnormal gene expression. We aimed to explore the differential expression of synaptic plasticity genes in chronic METH-treated mouse brain. We used the RT(2) Profiler PCR Array and the real-time quantitative PCR to characterize differentially expressed synaptic plasticity genes in the frontal cortex and the hippocampus of chronic METH-treated mice compared with normal saline-treated mice. We further used pyrosequencing to assess DNA methylation changes in the CpG region of the five immediate early genes (IEGs) in chronic METH-treated mouse brain. We detected six downregulated genes in the frontal cortex and the hippocampus of chronic METH-treated mice, including five IEGs (Arc, Egr2, Fos, Klf10, and Nr4a1) and one neuronal receptor gene (Grm1), compared with normal saline-treated group, but only four genes (Arc, Egr2, Fos, and Nr4a1) were confirmed to be different. Furthermore, we found several CpG sites of the Arc and the Fos that had significant changes in DNA methylation status in the frontal cortex of chronic METH-treated mice, while the klf10 and the Nr4a1 that had significant changes in the hippocampus. Our results show that chronic administration of METH may lead to significant downregulation of the IEGs expression in both the frontal cortex and the hippocampus, which may partly account for the molecular mechanism of the action of METH. Furthermore, the changes in DNA methylation status of the IEGs in the brain indicate that an epigenetic mechanism-dependent transcriptional regulation may contribute to METH addiction, which warrants additional study.

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.

Methamphetamine-induced sensitization is associated with alterations to the proteome of the prefrontal cortex: implications for the maintenance of psychotic disorders

Repeat administration of psychostimulants, such as methamphetamine, produces a progressive increase in locomotor activity (behavioral sensitization) in rodents that is believed to represent the underlying neurochemical changes driving psychoses. Alterations to the prefrontal cortex (PFC) are suggested to mediate the etiology and maintenance of these behavioral changes. As such, the aim of the current study was to investigate changes to protein expression in the PFC in male rats sensitized to methamphetamine using quantitative label-free shotgun proteomics. A methamphetamine challenge resulted in a significant sensitized locomotor response in methamphetamine pretreated animals compared to saline controls. Proteomic analysis revealed 96 proteins that were differentially expressed in the PFC of methamphetamine treated rats, with 20% of these being previously implicated in the neurobiology of schizophrenia in the PFC. We identified multiple biological functions in the PFC that appear to be commonly altered across methamphetamine-induced sensitization and schizophrenia, and these include synaptic regulation, protein phosphatase signaling, mitochondrial function, and alterations to the inhibitory GABAergic network. These changes could inform how alterations to the PFC could underlie the cognitive and behavioral dysfunction commonly seen across psychoses and places such biological changes as potential mediators in the maintenance of psychosis vulnerability.

Dopamine down-regulation of protein L-isoaspartyl methyltransferase is dependent on reactive oxygen species in SH-SY5Y cells

Parkinson's disease (PD) is a chronic and progressive neurological disorder that is characterized by the loss of dopaminergic neurons in the substantia nigra. Dopamine, via the oxidative stress that it generates in the cytosol, could contribute to the selective loss of neurons observed in PD. Protein L-isoaspartyl methyltransferase (PIMT) is an enzyme that repairs L-isoaspartyl-containing proteins and possesses anti-apoptotic properties. PIMT expression has been shown to decrease with age. Together, these observations prompted us to investigate whether dopamine can regulate PIMT expression in SH-SY5Y neuroblastoma cells. Here, we report that dopamine down-regulated PIMT at both gene and protein levels. The same inhibition of PIMT protein level was caused by the electron transport chain inhibitor, rotenone, which was accompanied, in both cases, by an increase in cell death and reactive oxygen species (ROS) production. In fact, pre-treatment with the antioxidant N-acetyl cysteine blocked PIMT dopamine-associated down-regulation. PCMT1 promoter mapping experiments allowed the identification of two regions that showed different sensitivity to DA action. A first region localized between 61 and 94bp upstream of transcription start site was very sensitive to dopamine inhibition while a second region between 41 and 61bp appeared more resistant to dopamine inhibitory effect. The inhibition of PCMT1 promoter activity was mediated by dopamine-induced ROS since it was prevented by the hydroxyl radical scavenger N,N'-dimethylthiourea. Conversely, H2O2 inhibited in a dose-dependent manner the transcriptional activity of PCMT1 promoter. Therefore, our findings identified new molecular mechanisms, cytosolic dopamine and its resulting ROS, as inhibitors of PIMT expression. This suggests that ROS generated from cytosolic dopamine could reduce both the PCMT1 gene promoter activity and the PIMT protein level thus decreasing its capacity to repair proteins involved in apoptosis and could contribute to neuronal cell death observed in PD.

Comparative peptidomics analysis of neural adaptations in rats repeatedly exposed to amphetamine

Repeated exposure to amphetamine (AMPH) induces long-lasting behavioral changes, referred to as sensitization, that are accompanied by various neuroadaptations in the brain. To investigate the chemical changes that occur during behavioral sensitization, we applied a comparative proteomics approach to screen for neuropeptide changes in a rodent model of AMPH-induced sensitization. By measuring peptide profiles with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and comparing signal intensities using principal component analysis and variance statistics, subsets of peptides are found with significant differences in the dorsal striatum, nucleus accumbens, and medial prefrontal cortex of AMPH-sensitized male Sprague-Dawley rats. These biomarker peptides, identified in follow-up analyses using liquid chromatography and tandem mass spectrometry, suggest that behavioral sensitization to AMPH is associated with complex chemical adaptations that regulate energy/metabolism, neurotransmission, apoptosis, neuroprotection, and neuritogenesis, as well as cytoskeleton integrity and neuronal morphology. Our data contribute to a growing number of reports showing that in addition to the mesolimbic dopamine system, which is the best known signaling pathway involved with reinforcing the effect of psychostimulants, concomitant chemical changes in other pathways and in neuronal organization may play a part in the overall effect of chronic AMPH exposure on behavior.

Effects of maternal separation and methamphetamine exposure on protein expression in the nucleus accumbens shell and core

Early life adversity has been suggested to predispose an individual to later drug abuse. The core and shell sub-regions of the nucleus accumbens are differentially affected by both stressors and methamphetamine. This study aimed to characterize and quantify methamphetamine-induced protein expression in the shell and core of the nucleus accumbens in animals exposed to maternal separation during early development. Isobaric tagging (iTRAQ) which enables simultaneous identification and quantification of peptides with tandem mass spectrometry (MS/MS) was used. We found that maternal separation altered more proteins involved in structure and redox regulation in the shell than in the core of the nucleus accumbens, and that maternal separation and methamphetamine had differential effects on signaling proteins in the shell and core. Compared to maternal separation or methamphetamine alone, the maternal separation/methamphetamine combination altered more proteins involved in energy metabolism, redox regulatory processes and neurotrophic proteins. Methamphetamine treatment of rats subjected to maternal separation caused a reduction of cytoskeletal proteins in the shell and altered cytoskeletal, signaling, energy metabolism and redox proteins in the core. Comparison of maternal separation/methamphetamine to methamphetamine alone resulted in decreased cytoskeletal proteins in both the shell and core and increased neurotrophic proteins in the core. This study confirms that both early life stress and methamphetamine differentially affect the shell and core of the nucleus accumbens and demonstrates that the combination of early life adversity and later methamphetamine use results in more proteins being affected in the nucleus accumbens than either treatment alone.

Genes and pathways co-associated with the exposure to multiple drugs of abuse, including alcohol, amphetamine/methamphetamine, cocaine, marijuana, morphine, and/or nicotine: a review of proteomics analyses

Drug addiction is a chronic neuronal disease. In recent years, proteomics technology has been widely used to assess the protein expression in the brain tissues of both animals and humans exposed to addictive drugs. Through this approach, a large number of proteins potentially involved in the etiology of drug addictions have been identified, which provide a valuable resource to study protein function, biochemical pathways, and networks related to the molecular mechanisms underlying drug dependence. In this article, we summarize the recent application of proteomics to profiling protein expression patterns in animal or human brain tissues after the administration of alcohol, amphetamine/methamphetamine, cocaine, marijuana, morphine/heroin/butorphanol, or nicotine. From available reports, we compiled a list of 497 proteins associated with exposure to one or more addictive drugs, with 160 being related to exposure to at least two abused drugs. A number of biochemical pathways and biological processes appear to be enriched among these proteins, including synaptic transmission and signaling pathways related to neuronal functions. The data included in this work provide a summary and extension of the proteomics studies on drug addiction. Furthermore, the proteins and biological processes highlighted here may provide valuable insight into the cellular activities and biological processes in neurons in the development of drug addiction.

Repeated mirtazapine nullifies the maintenance of previously established methamphetamine-induced conditioned place preference in rats

The atypical antidepressant mirtazapine enhances monoaminergic transmission; thus, mirtazapine therapy may counter the hypo-activation of monoamine systems associated with withdrawal from methamphetamine abuse. Human addiction therapy will likely require chronic administration that is given after brain and behavioral maladaptations are established. To emulate this scenario in rats, we ascertained if acute or repeated mirtazapine treatments could antagonize previously established consequences of repeated methamphetamine. Methamphetamine-induced conditioned place preference (CPP) was used, wherein methamphetamine (1mg/kg, i.p.) was administered in a unique environmental context once-daily for three days interposed by saline injections in an alternate context. Subsequently, mirtazapine (5mg/kg, i.p.) was administered in the home cage either as 10 once-daily injections or a single injection. The expression of CPP was determined in drug-free rats three days after the last mirtazapine injection. Expression of methamphetamine-induced CPP was inhibited by 10 home cage administrations of mirtazapine but not by a single injection of mirtazapine. These findings reveal that mirtazapine can inhibit the maintenance of methamphetamine-induced CPP and that treatment duration and/or treatment timing contributes to this effect of mirtazapine.