Striatal-enriched Tyrosine Protein Phosphatase (STEP) in the Mechanisms of Depressive Disorders

On Associations between Fear-Induced Aggression, Bdnf Transcripts, and Serotonin Receptors in the Brains of Norway Rats: An Influence of Antiaggressive Drug TC-2153

The Bdnf (brain-derived neurotrophic factor) gene contains eight regulatory exons (I-VIII) alternatively spliced to the protein-coding exon IX. Only exons I, II, IV, and VI are relatively well studied. The BDNF system and brain serotonergic system are tightly interconnected and associated with aggression. The benzopentathiepine TC-2153 affects both systems and exerts antiaggressive action. Our aim was to evaluate the effects of TC-2153 on the Bdnf exons I-IX's expressions and serotonin receptors' mRNA levels in the brain of rats featuring high aggression toward humans (aggressive) or its absence (tame). Aggressive and tame adult male rats were treated once with vehicle or 10 or 20 mg/kg of TC-2153. mRNA was quantified in the cortex, hippocampus, hypothalamus, and midbrain with real-time PCR. Selective breeding for high aggression or its absence affected the serotonin receptors' and Bdnf exons' transcripts differentially, depending on the genotype (strain) and brain region. TC-2153 had comprehensive effects on the Bdnf exons' expressions. The main trend was downregulation in the hypothalamus and midbrain. TC-2153 increased 5-HT_1B receptor hypothalamusc mRNA expression. For the first time, an influence of TC-2153 on the expressions of Bdnf regulatory exons and the 5-HT_1B receptor was shown, as was an association between Bdnf regulatory exons and fear-induced aggression involving genetic predisposition.

Transcriptomic Studies of Antidepressant Action in Rodent Models of Depression: A First Meta-Analysis

Antidepressants (ADs) are, for now, the best everyday treatment we have for moderate to severe major depressive episodes (MDEs). ADs are among the most prescribed drugs in the Western Hemisphere; however, the trial-and-error prescription strategy and side-effects leave a lot to be desired. More than 60% of patients suffering from major depression fail to respond to the first AD they are prescribed. For those who respond, full response is only observed after several weeks of treatment. In addition, there are no biomarkers that could help with therapeutic decisions; meanwhile, this is already true in cancer and other fields of medicine. For years, many investigators have been working to decipher the underlying mechanisms of AD response. Here, we provide the first systematic review of animal models. We thoroughly searched all the studies involving rodents, profiling transcriptomic alterations consecutive to AD treatment in naïve animals or in animals subjected to stress-induced models of depression. We have been confronted by an important heterogeneity regarding the drugs and the experimental settings. Thus, we perform a meta-analysis of the AD signature of fluoxetine (FLX) in the hippocampus, the most studied target. Among genes and pathways consistently modulated across species, we identify both old players of AD action and novel transcriptional biomarker candidates that warrant further investigation. We discuss the most prominent transcripts (immediate early genes and activity-dependent synaptic plasticity pathways). We also stress the need for systematic studies of AD action in animal models that span across sex, peripheral and central tissues, and pharmacological classes.

Fbxo45-mediated NP-STEP46 degradation via K6-linked ubiquitination sustains ERK activity in lung cancer

Lung cancer is one of the most threatening malignant tumors to human health. Epidermal growth factor receptor (EGFR)‐targeted therapy is a common and essential means for the clinical treatment of lung cancer. However, drug resistance has always affected the therapeutic effect and survival rate in non‐small cell lung cancer (NSCLC). Tumor heterogeneity is a significant reason, yielding various drug resistance mechanisms, such as EGFR‐dependent or ‐independent extracellular signal‐regulated kinase 1 and/or 2 (ERK1/2) activation in NSCLC. To examine whether this aberrant activation of ERK1/2 is related to the loss of function of its specific phosphatase, a series of in vitro and in vivo assays were performed. We found that F‐box/SPRY domain‐containing protein 1 (Fbxo45) induces ubiquitination of NP‐STEP₄₆, an active form of striatal‐enriched protein tyrosine phosphatase, with a K6‐linked poly‐ubiquitin chain. This ubiquitination led to proteasome degradation in the nucleus, which then sustains the aberrant level of phosphorylated‐ERK (pERK) and promotes tumor growth of NSCLC. Fbxo45 silencing can significantly inhibit cell proliferation and tumor growth. Moreover, NSCLC cells with silenced Fbxo45 showed great sensitivity to the EGFR tyrosine kinase inhibitor (TKI) afatinib. Here, we first report this critical pERK maintenance mechanism, which might be independent of the upstream kinase activity in NSCLC. We propose that inhibiting Fbxo45 may combat the issue of drug resistance in NSCLC patients, especially combining with EGFR‐TKI therapy.

Ambiguous Effects of Prolonged Dietary Supplementation with a Striatal-Enriched Protein Tyrosine Phosphatase Inhibitor, TC-2153, on a Rat Model of Sporadic Alzheimer’s Disease

Abstract

Alzheimer’s disease (AD) is the most common type of dementia and is currently incurable. After unsuccessful attempts to create drugs targeting the amyloid-β pathway, a search for alternative approaches and treatments targeting nonamyloid AD pathologies is currently underway. One of them is inhibition of striatal-enriched protein tyrosine phosphatase (STEP) activity, which is increased in the prefrontal cortex of AD patients. Here we examined effects of prolonged treatment of OXYS rats which mimic key signs of sporadic AD with a STEP inhibitor, TC-2153, on the progression of signs of AD. TC-2153 had an ambiguous effect on the behavior of the animals: it significantly reduced the already low locomotor and exploratory activities and enhanced anxiety-related behavior in OXYS rats but improved their long-term memory in the Morris water maze. Moreover, TC-2153 had no effect on the accumulation of the amyloid-β protein and on the STEP61 protein level; the latter in the cortex and hippocampus did not differ between OXYS rats and control Wistar rats. These results suggest that the effects of prolonged treatment with TC-2153 may be mediated by mechanisms not related to STEP. In particular, TC-2153 can act as a potential hydrogen sulfide donor and thus substantially affect redox homeostasis.

PTPN5 promotes follicle-stimulating hormone secretion through regulating intracellular calcium homeostasis

Protein tyrosine phosphatase non-receptor type 5 (PTPN5), also called striatal-enriched protein tyrosine phosphatase (STEP), is highly expressed in neurons of the basal ganglia, hippocampus, cortex, and related structures, also in the pituitary. Gonadotropins are the key regulator of the reproduction in mammals. In this study, PTPN5 is detected to express in murine pituitary in a developmental manner. Moreover, the expression of PTPN5 in the pituitary is heavily reduced after ovary removal. Follicle-stimulating hormone (FSH) secretion in gonadotropes is regulated by PTPN5 via binding GnRH to GnRH-R. Two parallel signaling pathways, Gs-protein kinase A (PKA)-PTPN5 and Gq-phospholipases C (PLC)-p38 MAPK-PTPN5, cooperatively regulate GnRH-induced FSH secretion. We also show that influx of Ca²⁺ activates the Ca²⁺ -dependent phosphatase calcineurin, leading to the phosphorylation and activation of PTPN5. The intracellular release of Ca²⁺ is reduced via TC2153. In conclusion, blocking or knocking out of PTPN5 reduces the release of FSH in whole pituitary. Mechanically, PTPN5 regulates gonadotropes' function through regulating intracellular calcium homeostasis.

Long Noncoding RNA Expression Profiles of Rat Extrasynaptic and Synaptic Neurons Expressing the N-methyl-D-Aspartate Receptor Revealed by Microarray Analysis

PURPOSE

To study the 24-hour expression of long noncoding RNAs (lncRNAs) in synaptic and extrasynaptic neurons expressing N-methyl-D-aspartate receptor (NMDAR), and normal neuronal cultures, via microarray analysis.

MATERIALS AND METHODS

Cortical neurons from embryonic (day E18) Sprague-Dawley rats were used for primary neuronal culture. NMDAR activation was blocked and the cells were then incubated for 6 hours. Total RNA was extracted, quantified, and analyzed for purity and integrity. Double-stranded cDNA was synthesized, followed by quantile normalization, quantitative polymerase chain reaction validation, and data analysis. The interactions between transcription factors and lncRNAs were analyzed by Pearson correlation.

RESULTS

The lncRNA profiles were obtained after synaptic and extrasynaptic NMDAR activation of rat cortical neuron cultures for 24 hours. In total, 251 lncRNAs were consistently upregulated, and 335 were downregulated, after extrasynaptic NMDAR activation compared with normal neurons. After synaptic NMDAR activation, only 9 lncRNAs were upregulated and 2 were downregulated.

CONCLUSIONS

Differential expression of lncRNAs after synaptic and extrasynaptic NMDAR activation suggests that lncRNAs may be responsible for extrasynaptic NMDAR-induced neurodegeneration.

The Implication of STEP in Synaptic Plasticity and Cognitive Impairments in Alzheimer's Disease and Other Neurological Disorders

STriatal-Enriched protein tyrosine Phosphatase (STEP) is a tyrosine phosphatase that has been implicated in Alzheimer’s disease (AD), the most common form of dementia, and many other neurological diseases. The protein level and activity of STEP have been found to be elevated in most of these disorders, and specifically in AD as a result of dysregulation of different pathways including PP2B/DARPP32/PP1, PKA as well as impairments of both proteasomal and lysosomal systems. The upregulation in STEP leads to increased binding to, and dephosphorylation of, its substrates which are mainly found to be synaptic plasticity and thus learning and memory related proteins. These proteins include kinases like Fyn, Pyk2, ERK1/2 and both NMDA and AMPA receptor subunits GluN2B and GluA2. The dephosphorylation of these molecules results in inactivation of these kinases and internalization of NMDA and AMPA receptor complexes leading to synapse loss and cognitive impairments. In this study, we aim to review STEP regulation and its implications in AD as well as other neurological disorders and then summarize data on targeting STEP as therapeutic strategy in these diseases.

Genetic underpinnings of affective temperaments: a pilot GWAS investigation identifies a new genome-wide significant SNP for anxious temperament in ADGRB3 gene

Although recently a large-sample GWASs identified significant loci in the background of depression, the heterogeneity of the depressive phenotype and the lack of accurate phenotyping hinders applicability of findings. We carried out a pilot GWAS with in-depth phenotyping of affective temperaments, considered as subclinical manifestations and high-risk states for affective disorders, in a general population sample of European origin. Affective temperaments were measured by TEMPS-A. SNP-level association was assessed by linear regression models, assuming an additive genetic effect, using PLINK1.9. Gender, age, the first ten principal components (PCs) and the other four temperaments were included in the regression models as covariates. SNP-level relevances (p-values) were aggregated to gene level using the PEGASUS method¹. In SNP-based tests, a Bonferroni-corrected significance threshold of p ≤ 5.0 × 10^-8 and a suggestive significance threshold of p ≤ 1.0 × 10^-5, whereas in gene-based tests a Bonferroni-corrected significance of 2.0 × 10^-6 and a suggestive significance of p ≤ 4.0 × 10^-4 was established. To explore known functional effects of the most significant SNPs, FUMA v1.3.5 was used. We identified 1 significant and 21 suggestively significant SNPs in ADGRB3, expressed in the brain, for anxious temperament. Several other brain-relevant SNPs and genes emerged at suggestive significance for the other temperaments. Functional analyses reflecting effect on gene expression and participation in chromatin interactions also pointed to several genes expressed in the brain with potentially relevant phenotypes regulated by our top SNPs. Our findings need to be tested in larger GWA studies and candidate gene analyses in well-phenotyped samples in relation to affective disorders and related phenotypes.

Insight into the Role of the STriatal-Enriched Protein Tyrosine Phosphatase (STEP) in A2A Receptor-Mediated Effects in the Central Nervous System

The STriatal-Enriched protein tyrosine phosphatase STEP is a brain-specific tyrosine phosphatase that plays a pivotal role in the mechanisms of learning and memory, and it has been demonstrated to be involved in several neuropsychiatric diseases. Recently, we found a functional interaction between STEP and adenosine A_2A receptor (A_2AR), a subtype of the adenosine receptor family widely expressed in the central nervous system, where it regulates motor behavior and cognition, and plays a role in cell survival and neurodegeneration. Specifically, we demonstrated the involvement of STEP in A_2AR-mediated cocaine effects in the striatum and, more recently, we found that in the rat striatum and hippocampus, as well as in a neuroblastoma cell line, the overexpression of the A_2AR, or its stimulation, results in an increase in STEP activity. In the present article we will discuss the functional implication of this interaction, trying to examine the possible mechanisms involved in this relation between STEP and A_2ARs.

Acute Administration of Imipramine and Citalopram Increases Activity of Striatal-Enriched Tyrosine Protein Phosphatase (STEP) in Brain of Zebrafish Danio rerio

Effects of acute treatment with antidepressant drugs, imipramine and citalopram, on behavior and activity of striatal-enriched tyrosine protein phosphatase (STEP) in the whole brain of zebrafish Danio rerio were studied. Mature zebrafish were exposed for 3 h to water (control) or to solutions of 0.25, 0.5, or 1 mg/liter of imipramine or citalopram, and then their behavior was studied in novel tank test. STEP activity was assayed in the brain of animals by the difference between the rates of transformation of p-nitrophenyl phosphate to 4-nitrophenol in the absence or presence of a selective STEP inhibitor. In novel tank test, imipramine and citalopram reduced locomotor activity and increased freezing time; at this, imipramine increased the total time spent in top of the tank. Citalopram (all concentrations) and imipramine (0.5 and 1 mg/liter) increased STEP activity in zebrafish brain.

Aging-related modifications to G protein-coupled receptor signaling diversity

Aging is a highly complex molecular process, affecting nearly all tissue systems in humans and is the highest risk factor in developing neurodegenerative disorders such as Alzheimer's and Parkinson's disease, cardiovascular disease and Type 2 diabetes mellitus. The intense complexity of the aging process creates an incentive to develop more specific drugs that attenuate or even reverse some of the features of premature aging. As our current pharmacopeia is dominated by therapeutics that target members of the G protein-coupled receptor (GPCR) superfamily it may be prudent to search for effective anti-aging therapeutics in this fertile domain. Since the first demonstration of GPCR-based β-arrestin signaling, it has become clear that an enhanced appreciation of GPCR signaling diversity may facilitate the creation of therapeutics with selective signaling activities. Such 'biased' ligand signaling profiles can be effectively investigated using both standard molecular biological techniques as well as high-dimensionality data analyses. Through a more nuanced appreciation of the quantitative nature across the multiple dimensions of signaling bias that drugs possess, researchers may be able to further refine the efficacy of GPCR modulators to impact the complex aberrations that constitute the aging process. Identifying novel effector profiles could expand the effective pharmacopeia and assist in the design of precision medicines. This review discusses potential non-G protein effectors, and specifically their potential therapeutic suitability in aging and age-related disorders.

Alterations of STEP46 and STEP61 Expression in the Rat Retina with Age and AMD-Like Retinopathy Development

Tyrosine phosphatase STEP (striatal-enriched tyrosine protein phosphatase) is a brain-specific protein phosphatase and is involved in the pathogenesis of many neurodegenerative diseases. Here, we examined the impact of STEP on the development of age-related macular degeneration (AMD)-like pathology in senescence-accelerated OXYS rats. Using OXYS and Wistar rats (control), we for the first time demonstrated age-dependent changes in Ptpn5 mRNA expression, STEP46 and STEP61 protein levels, and their phosphatase activity in the retina. The increases in STEP protein levels and the decrease of total and STEP phosphatase activities in the retina (as compared with Wistar rats) preceded the manifestation of clinical signs of AMD in OXYS rats (age 20 days). There were no differences in these retinal parameters between 13-month-old Wistar rats and OXYS rats with pronounced signs of AMD. Inhibition of STEP with TC-2153 during progressive AMD-like retinopathy (from 9 to 13 months of age) reduced the thickness of the retinal inner nuclear layer, as evidenced by a decreased amount of parvalbumin-positive amacrine neurons. Prolonged treatment with TC-2153 had no effect on Ptpn5 mRNA expression, STEP46 and STEP61 protein levels, and their phosphatase activity in the OXYS retina. Thus, TC-2153 may negatively affect the retina through mechanisms unrelated to STEP.

Effects of Acute and Chronic Treatment of Novel Psychotropic Drug, 8- (Trifluoromethyl)-1, 2, 3, 4, 5-benzopentathiepin-6-amine Hydrochloride (TC-2153), on the Behavior of Zebrafish (Danio Rerio): A Comparison with Fluoxetine

Background:

Striatal-enriched Tyrosine Phosphatase (STEP) plays a key role in the mechanisms of neuronal signaling and is a potential molecular target for new generation of psychotropic drugs. STEP inhibitor, 8-(trifluoromethyl-1,2,3,4,5-benzopentathiepin-6-amine hydrochloride (TC-2153), shows anxiolytic effect on mice. Zebrafish (Danio rerio) is a suitable model for the study of anxiety pharmacology.

Objective:

The objective of this study is to investigate the effects of acute and chronic TC-2153 treatment on zebrafish anxiety-related behavior.

Methods:

The effects of acute (0.125 and 0.25 mg/l, 3 h) and chronic (0.125 mg/l, 14 days) administration of TC-2153 on locomotion and anxiety-related behavior (time spent near the bottom and mean distance from the bottom) of adult zebrafish in the Novel Tank (NT) test were compared with those of the same doses of fluoxetine chosen as a positive control.

Results:

Acute treatment with 0.125 mg/l and 0.25 mg/l of TC-2153 or fluoxetine decreased time spent near the bottom, increased time spent near the surface and increased mean distance from the bottom of tank. Chronic treatment with 0.125 mg/l of TC-2153 reduced only time spent near the tank bottom without any effect on time spent near the surface and mean distance from the bottom, while chronic administration of 0.125 mg/l of fluoxetine altered these three indices of anxiety.

Conclusion:

Both acute and chronic TC-2153 produces anxiety-like effect indicating STEP involved in the mechanism of anxiety-related behavior in zebrafish. At the same time, chronic treatment with TC-2153 reduced locomotor activity. Zebrafish is a promising laboratory object to study the role of STEP in the nervous system.

Signal Transduction Pathways of Acupuncture for Treating Some Nervous System Diseases

In this article, we review signal transduction pathways through which acupuncture treats nervous system diseases. We electronically searched the databases, including PubMed, MEDLINE, clinical Key, the Cochrane Library, and the China National Knowledge Infrastructure from their inception to December 2018 using the following MeSH headings and keywords alone or in varied combination: acupuncture, molecular, signal transduction, genetic, cerebral ischemic injury, cerebral hemorrhagic injury, stroke, epilepsy, seizure, depression, Alzheimer's disease, dementia, vascular dementia, and Parkinson's disease. Acupuncture treats nervous system diseases by increasing the brain-derived neurotrophic factor level and involves multiple signal pathways, including p38 MAPKs, Raf/MAPK/ERK 1/2, TLR4/ERK, PI3K/AKT, AC/cAMP/PKA, ASK1-JNK/p38, and downstream CREB, JNK, m-TOR, NF-κB, and Bcl-2/Bax balance. Acupuncture affects synaptic plasticity, causes an increase in neurotrophic factors, and results in neuroprotection, cell proliferation, antiapoptosis, antioxidant activity, anti-inflammation, and maintenance of the blood-brain barrier.

The susceptibility to chronic social defeat stress is related to low hippocampal extrasynaptic NMDA receptor function

N-methyl-D-aspartate receptors (NMDARs) have been highly implicated in the pathogenesis and treatment of depression. While NMDARs can be found inside and outside glutamate synapses, it remains unclear if NMDARs at synaptic (sNMDAR) and extrasynaptic locations (exNMDAR) play different roles in the formation of depression-related behaviors. Using chronic social defeat stress (CSDS), an animal model for anxiety- and depression-related behaviors, we found that mice susceptible to CSDS exhibited low hippocampal exNMDAR function. Raising exNMDAR function by enhancing the release of glutamate from astrocytic cystine-glutamate antiporters or targeting extrasynaptic receptors with agonist-coated gold nanoparticles that cannot enter the synaptic cleft prevented social avoidance behavior in stressed mice. Interestingly, ketamine, which is a fast-acting antidepressant, exhibited stronger blockade to sNMDARs than to exNMDARs. These findings suggest that the susceptibility and resilience of mice toward CSDS is related to low and high exNMDAR function in the hippocampus, respectively. Enhancing exNMDAR function could be a novel treatment approach for mood and anxiety disorders.

Distinguishing and phenotype monitoring of traumatic brain injury and post-concussion syndrome including chronic migraine in serum of Iraq and Afghanistan war veterans

Traumatic Brain Injury (TBI) and persistent post-concussion syndrome (PCS) including chronic migraine (CM) are major health issues for civilians and the military. It is important to understand underlying biochemical mechanisms of these conditions, and be able to monitor them in an accurate and minimally invasive manner. This study describes the initial use of a novel serum analytical platform to help distinguish TBI patients, including those with post-traumatic headache (PTH), and to help identify phenotypes at play in these disorders. The hypothesis is that physiological responses to disease states like TBI and PTH and related bodily stresses are reflected in biomolecules in the blood in disease-specific manner. Leave one out (serum sample) cross validations (LOOCV) and sample randomizations were utilized to distinguished serum samples from the following TBI patient groups: TBI +PTSD + CM + severe depression (TBI "most affected" group) vs healthy controls, TBI "most affected" vs TBI, TBI vs controls, TBI + CM vs controls, and TBI + CM vs TBI. Inter-group discriminatory p values were ≤ 10-10, and sample group randomizations resulted in p non-significant values. Peptide/protein identifications of discriminatory mass peaks from the TBI "most affected" vs controls and from the TBI plus vs TBI minus CM groups yielded information of the cellular/molecular effects of these disorders (immune responses, amyloidosis/Alzheimer's disease/dementia, neuronal development). More specific biochemical disease effects appear to involve blood brain barrier, depression, migraine headache, autoimmunity, and autophagy pathways. This study demonstrated the ability for the first time of a novel, accurate, biomarker platform to monitor these conditions in serum, and help identify biochemical relationships leading to better understanding of these disorders and to potential therapeutic approaches.

Inhibitor of Striatal-Enriched Protein Tyrosine Phosphatase, 8-(Trifluoromethyl)-1,2,3,4,5-Benzopentathiepin-6-Amine hydrochloride (TC-2153), Produces Antidepressant-Like Effect and Decreases Functional Activity and Protein Level of 5-HT2A Receptor in the Brain

The serotoninergic 5-HT_2A receptor is involved in the mechanism of depression and antidepressant drugs action. Earlier we showed that striatal-enriched protein tyrosine phosphatase (STEP) inhibitor - 8-(trifluoromethyl)-1,2,3,4,5-benzopentathiepin-6-amine hydrochloride (TC-2153) affects both the brain serotoninergic system and the brain-derived neurotropic factor that are known to be involved in the psychopathology of depression. In the present study we investigated the effects of chronic TC-2153 administration on behavior in the standard battery of tests as well as the effects of acute and chronic TC-2153 treatment on the brain 5-HT_2A receptors in mice. We obtained a prominent antidepressant-like effect of chronic TC-2153 treatment in the forced swim test without any adverse side effects on locomotor activity, anxiety, exploration, motor skill and obsessive-compulsive-like behavior. Moreover, both acute and chronic TC-2153 administration inhibited the functional activity of 5-HT_2A receptors estimated by the number of 2,5-dimethoxy-4-iodoamphetamine (DOI, agonist of 5-HT_2A receptors)-induced head-twitches. TC-2153 treatment also attenuated the DOI-induced c-fos expression in cortical and hippocampal neurons and reduced the 5-HT_2A receptor protein level in the hippocampus and frontal cortex, but not in the striatum. Taken together, our combined data demonstrate that the antidepressant effect of STEP inhibitor TC-2153 could be mediated by its inhibitory properties towards the 5-HT_2A receptor-mediated signaling.