Genetic analysis of the calcineurin pathway identifies members of the EGR gene family, specifically EGR3, as potential susceptibility candidates in schizophrenia

Altered Expression of Neuroplasticity-Related Genes in Alcohol Addiction and Treatment

Alcohol use disorder's complexity arises from genetic and environmental factors, with alcohol metabolism genes and neurotransmitter pathways being critical. This study aims to analyze synaptic plasticity gene expression changes in individuals with AUD in order to study their contribution to AUD development and to identify potential biomarkers of treatment response. RNA was extracted from whole peripheral blood (20 patients, 10 healthy controls), before and after treatment (Qiagen AllPrep RNA/DNA Mini Kit), and the gene expression of 84 genes related to neuroplasticity was studied using the RT2 Profiler for Human Synaptic Plasticity RT-PCR Array (PAHS-126ZA, Qiagen), comparing AUD patients to control and responders to non-responders. The potential prognostic/predictive biomarkers were searched using machine learning models. A total of 35 dysregulated genes were found in AUD patients. EPHB2, EGR, and AKT1 were increased, while TIMP1, NCAM1, and GRM2 were decreased. Responders showed distinct gene expression profiles at baseline. After treatment, the expression of 57 genes was normalized, while NCAM1, GRM2, and BDNF showed the most significant recovery. EGR4, INHBA, and NCAM1 emerged as potential biomarkers to predict treatment success. These results indicate that gene profiles in peripheral blood can serve as prognostic markers for the prognosis and treatment of AUD, although further validation is required.

The role and molecular mechanisms of the early growth response 3 gene in schizophrenia

Schizophrenia is a chronic, debilitating mental illness caused by both genetic and environmental factors. Genetic factors play a major role in schizophrenia development. Early growth response 3 (EGR3) is a member of the EGR family, which is associated with schizophrenia. Accumulating studies have investigated the relationship between EGR3 and schizophrenia. However, the role of EGR3 in schizophrenia pathogenesis remains unclear. In the present review, we focus on the progress of research related to the role of EGR3 in schizophrenia, including association studies between EGR3 and schizophrenia, abnormal gene expressional analysis of EGR3 in schizophrenia, biological function studies of EGR3 in schizophrenia, the molecular regulatory mechanism of EGR3 and schizophrenia susceptibility candidate genes, and possible role of EGR3 in the immune system function in schizophrenia. In summary, EGR3 is a schizophrenia risk candidate factor and has comprehensive regulatory roles in schizophrenia pathogenesis. Further studies investigating the molecular mechanisms of EGR3 in schizophrenia are warranted for understanding the pathophysiology of this disorder as well as the development of new therapeutic strategies for the treatment and control of this disorder.

Behavioral and transcriptional effects of repeated electroconvulsive seizures in the neonatal MK-801-treated rat model of schizophrenia

RATIONALE

Electroconvulsive therapy (ECT) is an effective treatment modality for schizophrenia. However, its antipsychotic-like mechanism remains unclear.

OBJECTIVES

To gain insight into the antipsychotic-like actions of ECT, this study investigated how repeated treatments of electroconvulsive seizure (ECS), an animal model for ECT, affect the behavioral and transcriptomic profile of a neurodevelopmental animal model of schizophrenia.

METHODS

Two injections of MK-801 or saline were administered to rats on postnatal day 7 (PN7), and either repeated ECS treatments (E10X) or sham shock was conducted daily from PN50 to PN59. Ultimately, the rats were divided into vehicle/sham (V/S), MK-801/sham (M/S), vehicle/ECS (V/E), and MK-801/ECS (M/E) groups. On PN59, prepulse inhibition and locomotor activity were tested. Prefrontal cortex transcriptomes were analyzed with mRNA sequencing and network and pathway analyses, and quantitative real-time polymerase chain reaction (qPCR) analyses were subsequently conducted.

RESULTS

Prepulse inhibition deficit was induced by MK-801 and normalized by E10X. In M/S vs. M/E model, Egr1, Mmp9, and S100a6 were identified as center genes, and interleukin-17 (IL-17), nuclear factor kappa B (NF-κB), and tumor necrosis factor (TNF) signaling pathways were identified as the three most relevant pathways. In the V/E vs. V/S model, mitophagy, NF-κB, and receptor for advanced glycation end products (RAGE) pathways were identified. qPCR analyses demonstrated that Igfbp6, Btf3, Cox6a2, and H2az1 were downregulated in M/S and upregulated in M/E.

CONCLUSIONS

E10X reverses the behavioral changes induced by MK-801 and produces transcriptional changes in inflammatory, insulin, and mitophagy pathways, which provide mechanistic insight into the antipsychotic-like mechanism of ECT.

EGR3 Polymorphism Is a Potential Susceptibility Factor of Schizophrenia Risk in a Chinese Population

Objective: The purpose of this study was to evaluate the association between the single nucleotide polymorphisms (SNPs) (EGR3 rs1996147; EGR4 rs3813226, rs6747506; ERBB3 rs2292238; and ERBB4 rs707284, rs7560730) and the risk of schizophrenia (SZ) in a Chinese population. Materials and Methods: We conducted a case-control study, including 248 patients with SZ and 236 healthy controls matched for age and sex. The Mass-array platform was used to detect all the genotypes of the SNPs. Results: The results revealed that the EGR3 rs1996147 AA genotype was associated with borderline decreased SZ risk (AA vs. GG: adjusted OR = 0.43, 95% CI: 0.18-1.02, p = 0.06). However, no significant correlation was found between the other SNPs and overall SZ risk. Subgroup analysis also failed to show any significant association between all SNPs and the risk of SZ. Conclusion: In summary, this study revealed that the EGR3 rs1996147 AA genotype was associated with a borderline risk for SZ.

A comprehensive update on genetic inheritance, epigenetic factors, associated pathology, and recent therapeutic intervention by gene therapy in schizophrenia

Schizophrenia is a severe psychological disorder in which reality is interpreted abnormally by the patient. The symptoms of the disease include delusions and hallucinations, associated with extremely disordered behavior and thinking, which may affect the daily lives of the patients. Advancements in technology have led to understanding the dynamics of the disease and the identification of the underlying causes. Multiple investigations prove that it is regulated genetically, and epigenetically, and is affected by environmental factors. The molecular and neural pathways linked to the regulation of schizophrenia have been extensively studied. Over 180 Schizophrenic risk loci have now been recognized due to several genome-wide association studies (GWAS). It has been observed that multiple transcription factors (TF) binding-disrupting single nucleotide polymorphisms (SNPs) have been related to gene expression responsible for the disease in cerebral complexes. Copy number variation, SNP defects, and epigenetic changes in chromosomes may cause overexpression or underexpression of certain genes responsible for the disease. Nowadays, gene therapy is being implemented for its treatment as several of these genetic defects have been identified. Scientists are trying to use viral vectors, miRNA, siRNA, and CRISPR technology. In addition, nanotechnology is also being applied to target such genes. The primary aim of such targeting was to either delete or silence such hyperactive genes or induce certain genes that inhibit the expression of these genes. There are challenges in delivering the gene/DNA to the site of action in the brain, and scientists are working to resolve the same. The present article describes the basics regarding the disease, its causes and factors responsible, and the gene therapy solutions available to treat this disease.

Streptolysin S induces pronounced calcium-ion influx-dependent expression of immediate early genes encoding transcription factors

Anginosus group streptococci (AGS) are opportunistic human pathogens of the oral cavity. The β-hemolytic subgroup of Streptococcus anginosus subsp. anginosus secretes streptolysin S (SLS) and exhibits not only hemolytic activity but also cytotoxicity toward cultured human cell lines. However, the detailed mechanism of action of SLS and the cellular responses of host cells have not yet been fully clarified. To determine the pathogenic potential of SLS-producing β-hemolytic S. anginosus subsp. anginosus, the SLS-dependent response induced in the human oral squamous cell carcinoma HSC-2 cells was investigated to determine the pathogenic potential of SLS-producing β-hemolytic S. anginosus subsp. anginosus. This study revealed that the Ca2+ influx and the expression of immediate early genes (IEGs) encoding transcription factors such as early growth responses (EGRs) and activator protein-1 (AP-1) were greatly increased in HSC-2 cells incubated with the culture supernatant of SLS-producing β-hemolytic S. anginosus subsp. anginosus. Moreover, this SLS-dependent increase in expression was significantly suppressed by Ca2+ chelation, except for jun. These results suggest that SLS caused Ca2+ influx into the cells following greatly enhanced expression of IEG-encoding transcription factors. The results of this study may help in understanding the pathogenicity of SLS-producing AGS.

Acute psilocybin increased cortical activities in rats

Psilocybin, a naturally occurring hallucinogenic component of magic mushrooms, has significant psychoactive effects in both humans and rodents. But the underlying mechanisms are not fully understood. Blood-oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is a useful tool in many preclinical and clinical trials to investigate psilocybin-induced changes of brain activity and functional connectivity (FC) due to its noninvasive nature and widespread availability. However, fMRI effects of psilocybin on rats have not been carefully investigated. This study aimed to explore how psilocybin affects resting-state brain activity and FC, through a combination of BOLD fMRI and immunofluorescence (IF) of EGR1, an immediate early gene (IEG) closely related to depressive symptoms. Ten minutes after psilocybin hydrochloride injection (2.0 mg/kg, i.p.), positive brain activities were observed in the frontal, temporal, and parietal cortex (including the cingulate cortex and retrosplenial cortex), hippocampus, and striatum. And a region-of-interest (ROI) -wise FC analysis matrix suggested increased interconnectivity of several regions, such as the cingulate cortex, dorsal striatum, prelimbic, and limbic regions. Further seed-based analyses revealed increased FC of cingulate cortex within the cortical and striatal areas. Consistently, acute psilocybin increased the EGR1 level throughout the brain, indicating a consistent activation thought the cortical and striatal areas. In conclusion, the psilocybin-induced hyperactive state of rats is congruent to that of humans, and may be responsible for its pharmacological effects.

Serial electroconvulsive Seizure alters dendritic complexity and promotes cellular proliferation in the mouse dentate gyrus; a role for Egr3

BACKGROUND

Despite being one of the safest, most effective treatments for severe mood disorders, the therapeutic mechanisms of electroconvulsive therapy remain unknown. Electroconvulsive seizure (ECS) induces rapid, high-level expression of immediate early genes (IEGs) and brain-derived neurotrophic factor (BDNF), in addition to stimulation of neurogenesis and dendritic remodeling of dentate gyrus (DG) neurons. We have previously shown that this upregulation of BDNF fails to occur in the hippocampus of mice lacking the IEG Egr3. Since BDNF influences neurogenesis and dendritic remodeling, we hypothesized that Egr3-/- mice will exhibit deficits in neurogenesis and dendritic remodeling in response to ECS.

OBJECTIVE

To test this hypothesis, we examined dendritic remodeling and cellular proliferation in the DG of Egr3-/- and wild-type mice following repeated ECS.

METHODS

Mice received 10 daily ECSs. Dendritic morphology was examined in Golgi-Cox-stained tissue and cellular proliferation was analyzed through bromodeoxyuridine (BrdU) immunohistochemistry and confocal imaging.

RESULTS

Serial ECS in mice results in dendritic remodeling, increased spine density, and cellular proliferation in the DG. Loss of Egr3 alters the dendritic remodeling induced by serial ECS but does not change the number of dendritic spines or cellular proliferation consequences of ECS.

CONCLUSION

Egr3 influences the dendritic remodeling induced by ECS but is not required for ECS-induced proliferation of hippocampal DG cells.

Relating enhancer genetic variation across mammals to complex phenotypes using machine learning

Protein-coding differences between species often fail to explain phenotypic diversity, suggesting the involvement of genomic elements that regulate gene expression such as enhancers. Identifying associations between enhancers and phenotypes is challenging because enhancer activity can be tissue-dependent and functionally conserved despite low sequence conservation. We developed the Tissue-Aware Conservation Inference Toolkit (TACIT) to associate candidate enhancers with species' phenotypes using predictions from machine learning models trained on specific tissues. Applying TACIT to associate motor cortex and parvalbumin-positive interneuron enhancers with neurological phenotypes revealed dozens of enhancer-phenotype associations, including brain size-associated enhancers that interact with genes implicated in microcephaly or macrocephaly. TACIT provides a foundation for identifying enhancers associated with the evolution of any convergently evolved phenotype in any large group of species with aligned genomes.

Forebrain-specific conditional calcineurin deficiency induces dentate gyrus immaturity and hyper-dopaminergic signaling in mice

Calcineurin (Cn), a phosphatase important for synaptic plasticity and neuronal development, has been implicated in the etiology and pathophysiology of neuropsychiatric disorders, including schizophrenia, intellectual disability, autism spectrum disorders, epilepsy, and Alzheimer's disease. Forebrain-specific conditional Cn knockout mice have been known to exhibit multiple behavioral phenotypes related to these disorders. In this study, we investigated whether Cn mutant mice show pseudo-immaturity of the dentate gyrus (iDG) in the hippocampus, which we have proposed as an endophenotype shared by these disorders. Expression of calbindin and GluA1, typical markers for mature DG granule cells (GCs), was decreased and that of doublecortin, calretinin, phospho-CREB, and dopamine D1 receptor (Drd1), markers for immature GC, was increased in Cn mutants. Phosphorylation of cAMP-dependent protein kinase (PKA) substrates (GluA1, ERK2, DARPP-32, PDE4) was increased and showed higher sensitivity to SKF81297, a Drd1-like agonist, in Cn mutants than in controls. While cAMP/PKA signaling is increased in the iDG of Cn mutants, chronic treatment with rolipram, a selective PDE4 inhibitor that increases intracellular cAMP, ameliorated the iDG phenotype significantly and nesting behavior deficits with nominal significance. Chronic rolipram administration also decreased the phosphorylation of CREB, but not the other four PKA substrates examined, in Cn mutants. These results suggest that Cn deficiency induces pseudo-immaturity of GCs and that cAMP signaling increases to compensate for this maturation abnormality. This study further supports the idea that iDG is an endophenotype shared by certain neuropsychiatric disorders.

EGR3 regulates opioid-related nociception and motivation in male rats

Chronic pain can be a debilitating condition, leading to profound changes in nearly every aspect of life. However, the reliance on opioids such as oxycodone for pain management is thought to initiate dependence and addiction liability. The neurobiological intersection at which opioids relieve pain and possibly transition to addiction is poorly understood. Using RNA sequencing pathway analysis in rats with complete Freund's adjuvant (CFA)-induced chronic inflammation, we found that the transcriptional signatures in the medial prefrontal cortex (mPFC; a brain region where pain and reward signals integrate) elicited by CFA in combination with oxycodone differed from those elicited by CFA or oxycodone alone. However, the expression of Egr3 was augmented in all animals receiving oxycodone. Furthermore, virus-mediated overexpression of EGR3 in the mPFC increased mechanical pain relief but not the affective aspect of pain in animals receiving oxycodone, whereas pharmacological inhibition of EGR3 via NFAT attenuated mechanical pain relief. Egr3 overexpression also increased the motivation to obtain oxycodone infusions in a progressive ratio test without altering the acquisition or maintenance of oxycodone self-administration. Taken together, these data suggest that EGR3 in the mPFC is at the intersection of nociceptive and addictive-like behaviors.

Highly sensitive single-cell chromatin accessibility assay and transcriptome coassay with METATAC

The thriving field of single-cell genomics allows researchers to dissect the complexity and heterogeneity of tissues at single-cell resolution at large scale, involving transcriptome and epigenome. However, single-cell chromatin accessibility profiling methods exhibit low sensitivity. Here, we increased accessible chromatin detection sensitivity in single cells with METATAC, a single-cell ATAC-seq technique, with the help of META amplification strategy and other biochemical modifications. METATAC reached the highest accessible chromatin region detection efficiency compared with existing techniques, allowing more accurate cis-regulatory element coaccessibility measurement and allele-specific chromatin accessibility analysis in complex tissue samples. In combination with a high-resolution single-cell RNA sequencing assay, we further developed a high-sensitivity joint single-cell ATAC–RNA strategy, which helps us to better resolve gene regulatory programs.

Recent advances in single-cell assay for transposase accessible chromatin using sequencing (scATAC-seq) and its coassays have transformed the field of single-cell epigenomics and transcriptomics. However, the low detection efficiency of current methods has limited our understanding of the true complexity of chromatin accessibility and its relationship with gene expression in single cells. Here, we report a high-sensitivity scATAC-seq method, termed multiplexed end-tagging amplification of transposase accessible chromatin (METATAC), which detects a large number of accessible sites per cell and is compatible with automation. Our high detectability and statistical framework allowed precise linking of enhancers to promoters without merging single cells. We systematically investigated allele-specific accessibility in the mouse cerebral cortex, revealing allele-specific accessibility of promotors of certain imprinted genes but biallelic accessibility of their enhancers. Finally, we combined METATAC with our high-sensitivity single-cell RNA sequencing (scRNA-seq) method, multiple annealing and looping based amplification cycles for digital transcriptomics (MALBAC-DT), to develop a joint ATAC–RNA assay, termed METATAC and MALBAC-DT coassay by sequencing (M2C-seq). M2C-seq achieved significant improvements for both ATAC and RNA compared with previous methods, with consistent performance across cell lines and early mouse embryos.

Identification of activity-induced Egr3-dependent genes reveals genes associated with DNA damage response and schizophrenia

Bioinformatics and network studies have identified the immediate early gene transcription factor early growth response 3 (EGR3) as a master regulator of genes differentially expressed in the brains of patients with neuropsychiatric illnesses ranging from schizophrenia and bipolar disorder to Alzheimer's disease. However, few studies have identified and validated Egr3-dependent genes in the mammalian brain. We have previously shown that Egr3 is required for stress-responsive behavior, memory, and hippocampal long-term depression in mice. To identify Egr3-dependent genes that may regulate these processes, we conducted an expression microarray on hippocampi from wildtype (WT) and Egr3-/- mice following electroconvulsive seizure (ECS), a stimulus that induces maximal expression of immediate early genes including Egr3. We identified 69 genes that were differentially expressed between WT and Egr3-/- mice one hour following ECS. Bioinformatic analyses showed that many of these are altered in, or associated with, schizophrenia, including Mef2c and Calb2. Enrichr pathway analysis revealed the GADD45 (growth arrest and DNA-damage-inducible) family (Gadd45b, Gadd45g) as a leading group of differentially expressed genes. Together with differentially expressed genes in the AP-1 transcription factor family genes (Fos, Fosb), and the centromere organization protein Cenpa, these results revealed that Egr3 is required for activity-dependent expression of genes involved in the DNA damage response. Our findings show that EGR3 is critical for the expression of genes that are mis-expressed in schizophrenia and reveal a novel requirement for EGR3 in the expression of genes involved in activity-induced DNA damage response.

Targeting histone demethylase LSD1 for treatment of deficits in autism mouse models

Large-scale genetic studies have revealed that the most prominent genes disrupted in autism are chromatin regulators mediating histone methylation/demethylation, suggesting the central role of epigenetic dysfunction in this disorder. Here, we show that histone lysine 4 dimethylation (H3K4me2), a histone mark linked to gene activation, is significantly decreased in the prefrontal cortex (PFC) of autistic human patients and mutant mice with the deficiency of top-ranking autism risk factor Shank3 or Cul3. A brief treatment of the autism models with highly potent and selective inhibitors of the H3K4me2 demethylase LSD1 (KDM1A) leads to the robust rescue of core symptoms of autism, including social deficits and repetitive behaviors. Concomitantly, LSD1 inhibition restores NMDA receptor function in PFC and AMPA receptor-mediated currents in striatum of Shank3-deficient mice. Genome-wide RNAseq and ChIPseq reveal that treatment of Shank3-deficient mice with the LSD1 inhibitor restores the expression and H3K4me2 occupancy of downregulated genes enriched in synaptic signaling and developmental processes. The immediate early gene tightly linked to neuronal plasticity, Egr1, is on the top list of rescued genes. The diminished transcription of Egr1 is recapitulated in PFC of autistic human patients. Overexpression of Egr1 in PFC of Shank3-deficient mice ameliorates social preference deficits. These results have for the first time revealed an important role of H3K4me2 abnormality in ASD pathophysiology, and the therapeutic potential of targeting H3K4me2 demethylase LSD1 or the downstream molecule Egr1 for ASD.

Elevation of EGR1/zif268, a Neural Activity Marker, in the Auditory Cortex of Patients with Schizophrenia and its Animal Model

The family of epidermal growth factor (EGF) including neuregulin-1 are implicated in the neuropathology of schizophrenia. We established a rat model of schizophrenia by exposing perinatal rats to EGF and reported that the auditory pathophysiological traits of this model such as prepulse inhibition, auditory steady-state response, and mismatch negativity are relevant to those of schizophrenia. We assessed the activation status of the auditory cortex in this model, as well as that in patients with schizophrenia, by monitoring the three neural activity-induced proteins: EGR1 (zif268), c-fos, and Arc. Among the activity markers, protein levels of EGR1 were significantly higher at the adult stage in EGF model rats than those in control rats. The group difference was observed despite an EGF model rat and a control rat being housed together, ruling out the contribution of rat vocalization effects. These changes in EGR1 levels were seen to be specific to the auditory cortex of this model. The increase in EGR1 levels were detectable at the juvenile stage and continued until old ages but displayed a peak immediately after puberty, whereas c-fos and Arc levels were nearly indistinguishable between groups at all ages with an exception of Arc decrease at the juvenile stage. A similar increase in EGR1 levels was observed in the postmortem superior temporal cortex of patients with schizophrenia. The commonality of the EGR1 increase indicates that the EGR1 elevation in the auditory cortex might be one of the molecular signatures of this animal model and schizophrenia associating with hallucination.

Fading memories in aging and neurodegeneration: Is p75 neurotrophin receptor a culprit?

Aging and age-related neurodegenerative diseases have become one of the major concerns in modern times as cognitive abilities tend to decline when we get older. It is well known that the main cause of this age-related cognitive deficit is due to aberrant changes in cellular, molecular circuitry and signaling pathways underlying synaptic plasticity and neuronal connections. The p75 neurotrophin receptor (p75^NTR) is one of the important mediators regulating the fate of the neurons in the nervous system. Its importance in neuronal apoptosis is well documented. However, the mechanisms involving the regulation of p75^NTR in synaptic plasticity and cognitive function remain obscure, although cognitive impairment has been associated with a higher expression of p75^NTR in neurons. In this review, we discuss the current understanding of how neurons are influenced by p75^NTR function to maintain normal neuronal synaptic strength and connectivity, particularly to support learning and memory in the hippocampus. We then discuss the age-associated alterations in neurophysiological mechanisms of synaptic plasticity and cognitive function. Furthermore, we also describe current evidence that has begun to elucidate how p75^NTR regulates synaptic changes in aging and age-related neurodegenerative diseases, focusing on the hippocampus. Elucidating the role that p75^NTR signaling plays in regulating synaptic plasticity will contribute to a better understanding of cognitive processes and pathological conditions. This will in turn provide novel approaches to improve therapies for the treatment of neurological diseases in which p75^NTR dysfunction has been demonstrated.

Egr1 Is Necessary for Forebrain Dopaminergic Signaling during Social Behavior

Finding the link between behaviors and their regulatory molecular pathways is a major obstacle in treating neuropsychiatric disorders. The immediate early gene (IEG) EGR1 is implicated in the etiology of neuropsychiatric disorders, and is linked to gene pathways associated with social behavior. Despite extensive knowledge of EGR1 gene regulation at the molecular level, it remains unclear how EGR1 deficits might affect the social component of these disorders. Here, we examined the social behavior of zebrafish with a mutation in the homologous gene egr1 Mutant fish exhibited reduced social approach and orienting, whereas other sensorimotor behaviors were unaffected. On a molecular level, expression of the dopaminergic biosynthetic enzyme, tyrosine hydroxylase (TH), was strongly decreased in TH-positive neurons of the anterior parvocellular preoptic nucleus. These neurons are connected with basal forebrain (BF) neurons associated with social behavior. Chemogenetic ablation of around 30% of TH-positive neurons in this preoptic region reduced social attraction to a similar extent as the egr1 mutation. These results demonstrate the requirement of Egr1 and dopamine signaling during social interactions, and identify novel circuitry underlying this behavior.

Acute sleep deprivation upregulates serotonin 2A receptors in the frontal cortex of mice via the immediate early gene Egr3

Serotonin 2A receptors (5-HT_2ARs) mediate the hallucinogenic effects of psychedelic drugs and are a key target of the leading class of medications used to treat psychotic disorders. These findings suggest that dysfunction of 5-HT_2ARs may contribute to the symptoms of schizophrenia, a mental illness characterized by perceptual and cognitive disturbances. Indeed, numerous studies have found that 5-HT_2ARs are reduced in the brains of individuals with schizophrenia. However, the mechanisms that regulate 5-HT_2AR expression remain poorly understood. Here, we show that a physiologic environmental stimulus, sleep deprivation, significantly upregulates 5-HT_2AR levels in the mouse frontal cortex in as little as 6-8 h (for mRNA and protein, respectively). This induction requires the activity-dependent immediate early gene transcription factor early growth response 3 (Egr3) as it does not occur in Egr3 deficient (-/-) mice. Using chromatin immunoprecipitation, we show that EGR3 protein binds to the promoter of Htr2a, the gene that encodes the 5-HT_2AR, in the frontal cortex in vivo, and drives expression of in vitro reporter constructs via two EGR3 binding sites in the Htr2a promoter. These results suggest that EGR3 directly regulates Htr2a expression, and 5-HT_2AR levels, in the frontal cortex in response to physiologic stimuli. Analysis of publicly available post-mortem gene expression data revealed that both EGR3 and HTR2A mRNA are reduced in the prefrontal cortex of schizophrenia patients compared to controls. Together these findings suggest a mechanism by which environmental stimuli alter levels of a brain receptor that may mediate the symptoms, and treatment, of mental illness.

Identification of key long non-coding RNA-associated competing endogenous RNA axes in Brodmann Area 10 brain region of schizophrenia patients

Schizophrenia (SCZ) is a serious mental condition with an unknown cause. According to the reports, Brodmann Area 10 (BA10) is linked to the pathology and cortical dysfunction of SCZ, which demonstrates a number of replicated findings related to research on SCZ and the dysfunction in tasks requiring cognitive control in particular. Genetics' role in the pathophysiology of SCZ is still unclear. Therefore, it may be helpful to understand the effects of these changes on the onset and progression of SCZ to find novel mechanisms involved in the regulation of gene transcription. In order to determine the molecular regulatory mechanisms affecting the SCZ, the long non-coding RNA (lncRNA)-associated competing endogenous RNAs (ceRNAs) axes in the BA10 area were determined using a bioinformatics approach in the present work. A microarray dataset (GSE17612) consisted of brain post-mortem tissues of the BA10 area from SCZ patients and matched healthy subjects was downloaded from the Gene Expression Omnibus (GEO) database. This dataset included probes for both lncRNAs and mRNAs. Using the R software's limma package, the differentially expressed lncRNAs (DElncRNAs) and mRNAs (DEmRNAs) were found. The RNA interactions were also discovered using the DIANA-LncBase and miRTarBase databases. In the ceRNA network, positive correlations between DEmRNAs and DElncRNAs were evaluated using the Pearson correlation coefficient. Finally, lncRNA-associated ceRNA axes were built by using the co-expression and DElncRNA-miRNA-DEmRNA connections. We identified the DElncRNA-miRNA-DEmRNA axes, which included two key lncRNAs (PEG3-AS1, MIR570HG), seven key miRNAs (hsa-miR-124-3p, hsa-miR-17-5p, hsa-miR-181a-5p, hsa-miR-191-5p, hsa-miR-26a-5p, hsa-miR-29a-3p, hsa-miR-29b-3p), and eight key mRNAs (EGR1, ETV1, DUSP6, PLOD2, CD93, SERPINB9, ANGPTL4, TGFB2). Furthermore, DEmRNAs were found to be enriched in the "AGE-RAGE signaling pathway in diabetic complications", "Amoebiasis", "Transcriptional misregulation in cancer", "Human T-cell leukemia virus 1 infection", and "MAPK signaling pathway". This study offers research targets for examining significant molecular pathways connected to the pathogenesis of SCZ, even though the function of these ceRNA axes still needs to be investigated.

Decreased Lamin B1 Levels Affect Gene Positioning and Expression in Postmitotic Neurons

Gene expression programs and concomitant chromatin regulation change dramatically during the maturation of postmitotic neurons. Subnuclear positioning of gene loci is relevant to transcriptional regulation. However, little is known about subnuclear genome positioning in neuronal maturation. Using cultured murine hippocampal neurons, we found genomic locus 14qD2 to be enriched with genes that are upregulated during neuronal maturation. Reportedly, the locus is homologous to human 8p21.3, which has been extensively studied in neuropsychiatry and neurodegenerative diseases. Mapping of the 14qD2 locus in the nucleus revealed that it was relocated from the nuclear periphery to the interior. Moreover, we found a concomitant decrease in lamin B1 expression. Overexpression of lamin B1 in neurons using a lentiviral vector prevented the relocation of the 14qD2 locus and repressed the transcription of the Egr3 gene on this locus. Taken together, our results suggest that reduced lamin B1 expression during the maturation of neurons is important for appropriate subnuclear positioning of the genome and transcriptional programs.

Cooperation of LIM domain-binding 2 (LDB2) with EGR in the pathogenesis of schizophrenia

Genomic defects with large effect size can help elucidate unknown pathologic architecture of mental disorders. We previously reported on a patient with schizophrenia and a balanced translocation between chromosomes 4 and 13 and found that the breakpoint within chromosome 4 is located near the LDB2 gene. We show here that Ldb2 knockout (KO) mice displayed multiple deficits relevant to mental disorders. In particular, Ldb2 KO mice exhibited deficits in the fear-conditioning paradigm. Analysis of the amygdala suggested that dysregulation of synaptic activities controlled by the immediate early gene Arc is involved in the phenotypes. We show that LDB2 forms protein complexes with known transcription factors. Consistently, ChIP-seq analyses indicated that LDB2 binds to > 10,000 genomic sites in human neurospheres. We found that many of those sites, including the promoter region of ARC, are occupied by EGR transcription factors. Our previous study showed an association of the EGR family genes with schizophrenia. Collectively, the findings suggest that dysregulation in the gene expression controlled by the LDB2-EGR axis underlies a pathogenesis of subset of mental disorders.

Egr2 induction in spiny projection neurons of the ventrolateral striatum contributes to cocaine place preference in mice

Drug addiction develops due to brain-wide plasticity within neuronal ensembles, mediated by dynamic gene expression. Though the most common approach to identify such ensembles relies on immediate early gene expression, little is known of how the activity of these genes is linked to modified behavior observed following repeated drug exposure. To address this gap, we present a broad-to-specific approach, beginning with a comprehensive investigation of brain-wide cocaine-driven gene expression, through the description of dynamic spatial patterns of gene induction in subregions of the striatum, and finally address functionality of region-specific gene induction in the development of cocaine preference. Our findings reveal differential cell-type specific dynamic transcriptional recruitment patterns within two subdomains of the dorsal striatum following repeated cocaine exposure. Furthermore, we demonstrate that induction of the IEG Egr2 in the ventrolateral striatum, as well as the cells within which it is expressed, are required for the development of cocaine seeking.

The human brain is ever changing, constantly rewiring itself in response to new experiences, knowledge or information from the environment. Addictive drugs such as cocaine can hijack the genetic mechanisms responsible for this plasticity, creating dangerous, obsessive drug-seeking and consuming behaviors.

Cocaine-induced plasticity is difficult to apprehend, however, as brain regions or even cell populations can react differently to the compound. For instance, sub-regions in the striatum – the brain area that responds to rewards and helps to plan movement – show distinct responses during progressive exposure to cocaine. And while researchers know that the drug immediately changes how neurons switch certain genes on and off, it is still unclear how these genetic modifications later affect behavior.

Mukherjee, Gonzales et al. explored these questions at different scales, first focusing on how progressive cocaine exposure changed the way various gene programs were activated across the entire brain. This revealed that programs in the striatum were the most affected by the drug.

Examining this region more closely showed that cocaine switches on genes in specific ‘spiny projection’ neuron populations, depending on where these cells are located and the drug history of the mouse. Finally, Mukherjee, Gonzales et al. used genetically modified mice to piece together cocaine exposure, genetic changes and modifications in behavior. These experiments revealed that the drive to seek cocaine depended on activation of the Egr2 gene in populations of spiny projection neurons in a specific sub-region of the striatum. The gene, which codes for a protein that regulates how genes are switched on and off, was itself strongly activated by cocaine intake.

Cocaine addiction can have devastating consequences for individuals. Grasping how this drug alters the brain could pave the way for new treatments, while also providing information on the basic mechanisms underlying brain plasticity.

Regional brain network and behavioral alterations in EGR3 gene transfected rat model of schizophrenia

Schizophrenia is a severe psychiatric disease while its etiology and effective treatment are not completely clear. A rat model of schizophrenia was previously established by transfecting EGR3 gene into the hippocampus of rats. This study aimed to investigate the behavioral and cerebral alterations of the schizophrenic model rats and the risperidone effects. Twenty-six rats were divided into 3 groups: schizophrenia model group (E group), risperidone treatment group (T group), and healthy control group (H group). Morris water maze and open field test were used as behavioral tests, resting-state functional magnetic resonance imaging (fMRI) was performed after EGR3 gene transfection and risperidone therapy. Graph analyses were used for examining cerebral alterations of the rats. Behavioral tests demonstrated reduced spatial working memory and exploring unfamiliar space ability in schizophrenic model rats. Graph analyses revealed reduced regional architectures in the olfactory bulb, nucleus accumbens, and pineal gland in group E compared to group H (p < 0.05), while group T showed increased regional architecture in pineal gland compared to group E (p < 0.05). Besides, the regional architectures in the olfactory bulb, nucleus accumbens were lower in group T than group H, while the hippocampus showed increased regional architecture in group T compared to group H (p < 0.05). Schizophrenia induced several regional alterations in the cerebrum while risperidone can reverse part of these alterations. This study lends support for future research on the pathology of schizophrenia and provides new insights on the role of risperidone in schizophrenia.

8p21.3 deletions are rare causes of non-syndromic autism spectrum disorder

A de novo 0.95 Mb 8p21.3 deletion had been identified in an individual with non-syndromic autism spectrum disorder (ASD) through high-resolution copy number variant analysis. Subsequent screening of in-house and publicly available databases resulted in the identification of six additional individuals with 8p21.3 deletions. Through case-based reasoning, we conclude that 8p21.3 deletions are rare causes of non-syndromic neurodevelopmental and neuropsychiatric disorders. Based on literature data, we highlight six genes within the region of minimal overlap as potential ASD genes or genes for neuropsychiatric disorders: DMTN, EGR3, FGF17, LGI3, PHYHIP, and PPP3CC.

Schizophrenia risk candidate EGR3 is a novel transcriptional regulator of RELN and regulates neurite outgrowth via the Reelin signal pathway in vitro

Schizophrenia is a severe psychiatric disorder with a strong hereditary component that affects approximately 1% of the world's population. The disease is most likely caused by the altered expression of a number of genes that function at the level of biological pathways or gene networks. Transcription factors (TF) are indispensable regulators of gene expression. EGR3 is a TF associated with schizophrenia. In the current study, DNA microarray and ingenuity pathway analyses (IPA) demonstrated that EGR3 regulates Reelin signaling pathway in SH-SY5Y cells. ChIP and luciferase reporter studies confirmed that EGR3 directly binds to the promoter region of RELN thereby activating RELN expression. The expression of both EGR3 and RELN was decreased during neuronal differentiation induced by retinoic acid (RA) in SH-SY5Y cells, and EGR3 over-expression reduced neurite outgrowth which could be partially reversed by the knockdown of RELN. The expression levels of EGR3 and RELN in peripheral blood of subjects with schizophrenia were found to be down-regulated (compared with healthy controls), and were positively correlated. Furthermore, data mining from public databases revealed that the expression levels of EGR3 and RELN were presented a positive correlation in post-mortem brain tissue of subjects with schizophrenia. Taken together, this study suggests that EGR3 is a novel TF of the RELN gene and regulates neurite outgrowth via the Reelin signaling pathway. Our findings contribute to the understanding of the regulatory role of EGR3 in the pathophysiology and molecular mechanisms of schizophrenia, and potentially to the development of new therapies and diagnostic biomarkers for the disorder.

Early Growth Response Gene Upregulation in Epstein-Barr Virus (EBV)-Associated Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a chronic multisystem disease exhibiting a variety of symptoms and affecting multiple systems. Psychological stress and virus infection are important. Virus infection may trigger the onset, and psychological stress may reactivate latent viruses, for example, Epstein-Barr virus (EBV). It has recently been reported that EBV induced gene 2 (EBI2) was upregulated in blood in a subset of ME/CFS patients. The purpose of this study was to determine whether the pattern of expression of early growth response (EGR) genes, important in EBV infection and which have also been found to be upregulated in blood of ME/CFS patients, paralleled that of EBI2. EGR gene upregulation was found to be closely associated with that of EBI2 in ME/CFS, providing further evidence in support of ongoing EBV reactivation in a subset of ME/CFS patients. EGR1, EGR2, and EGR3 are part of the cellular immediate early gene response and are important in EBV transcription, reactivation, and B lymphocyte transformation. EGR1 is a regulator of immune function, and is important in vascular homeostasis, psychological stress, connective tissue disease, mitochondrial function, all of which are relevant to ME/CFS. EGR2 and EGR3 are negative regulators of T lymphocytes and are important in systemic autoimmunity.

Lipid Pathology of the Corpus Callosum in Schizophrenia and the Potential Role of Abnormal Gene Regulatory Networks with Reduced Microglial Marker Expression

Structural changes in the corpus callosum have been reported in schizophrenia; however, the underlying molecular mechanism remains unclear. As the corpus callosum is high in lipid content, we analyzed the lipid contents of the corpora callosa from 15 patients with schizophrenia and 15 age- and sex-matched controls using liquid chromatography coupled to tandem mass spectrometry and identified lipid combinations associated with schizophrenia. Real-time quantitative polymerase chain reaction analyses using extended samples (schizophrenia, n = 95; control, n = 91) showed low expression levels of lipid metabolism-related genes and their potential upstream transcription factors in schizophrenia. Subsequent pathway analysis identified a gene regulatory network where nuclear factor of activated T cells 2 (NFATC2) is placed most upstream. We also observed low gene expression levels of microglial markers, inflammatory cytokines, and colony-stimulating factor 1 receptor (CSF1R), which is known to regulate the density of microglia, in the corpus callosum in schizophrenia. The interactions between CSF1R and several genes in the presently identified gene network originating from NFATC2 have been reported. Collectively, this study provides evidence regarding lipid abnormalities in the corpora callosa of patients with schizophrenia and proposes the potential role of impaired “NFATC2-relevant gene network-microglial axis” as its underlying mechanism.

Multi-Scale Understanding of NMDA Receptor Function in Schizophrenia

Schizophrenia is a chronic and disabling psychiatric disorder characterized by disturbances of thought, cognition, and behavior. Despite massive research efforts to date, the etiology and pathophysiology of schizophrenia remain largely unknown. The difficulty of brain research is largely a result of complex interactions between contributory factors at different scales: susceptible gene variants (molecular scale), synaptopathies (synaptic, dendritic, and cell scales), and alterations in neuronal circuits (circuit scale), which together result in behavioral manifestations (individual scale). It is likely that each scale affects the others, from the microscale to the mesoscale to the macroscale, and vice versa. Thus, to consider the intricate complexity of schizophrenia across multiple layers, we introduce a multi-scale, hierarchical view of the nature of this disorder, focusing especially on N-methyl-D-aspartate-type glutamate receptors (NMDARs). The reason for placing emphasis on NMDAR is its clinical relevance to schizophrenia, as well as its diverse functions in neurons, including the robust supralinear synaptic integration provided by N-methyl-D-aspartate-type glutamate (NMDA) spikes and the Ca²⁺ permeability of the NMDAR, which facilitates synaptic plasticity via various calcium-dependent proteins. Here, we review recent evidence implicating NMDARs in the pathophysiology of schizophrenia from the multi-scale perspective. We also discuss recent advances from optical techniques, which provide a powerful tool for uncovering the mechanisms of NMDAR synaptic pathology and their relationships, with subsequent behavioral manifestations.

Are Circadian Disturbances a Core Pathophysiological Component of Schizophrenia?

Schizophrenia is a multifactorial disorder caused by a combination of genetic variations and exposure to environmental insults. Sleep and circadian rhythm disturbances are a prominent and ubiquitous feature of many psychiatric disorders, including schizophrenia. There is growing interest in uncovering the mechanistic link between schizophrenia and circadian rhythms, which may directly affect disorder outcomes. In this review, we explore the interaction between schizophrenia and circadian rhythms from 2 complementary angles. First, we review evidence that sleep and circadian rhythm disturbances constitute a fundamental component of schizophrenia, as supported by both human studies and animal models with genetic mutations related to schizophrenia. Second, we discuss the idea that circadian rhythm disruption interacts with existing risk factors for schizophrenia to promote schizophrenia-relevant behavioral and neurobiological abnormalities. Understanding the mechanistic link between schizophrenia and circadian rhythms will have implications for mitigating risk to the disorder and informing the development of circadian-based therapies.

Peripheral Blood Leukocyte RNA-Seq Identifies a Set of Genes Related to Abnormal Psychomotor Behavior Characteristics in Patients with Schizophrenia

BACKGROUND Schizophrenia is a multigene disease with a complex etiology and different clinical manifestations. It is of great significance to understand the etiology and pathogenesis of schizophrenia patients from different clinical dimensions and to interpret the potential molecular changes of schizophrenia patients from different clinical dimensions. MATERIAL AND METHODS RNA-Seq was performed on peripheral blood leukocytes of 50 patients with schizophrenia and 50 healthy controls. Phenotypic information of patients with schizophrenia was collected during blood sampling. Differentially expressed genes (DEGs) were screened by the edgeR package of R software. To better analyze the correlation between DEG expression values, explore the potential association between differential genes and clinical dimensions of schizophrenia, and identify hub genes, we constructed a DEG co-expression network using weighted gene co-expression network analysis (WGCNA). RESULTS We provide the transcription profiles of peripheral blood leukocytes in patients with schizophrenia and found a gene module (including 89 genes) closely related to the clinical dimension of abnormal psychomotor behavior in schizophrenia. CONCLUSIONS The findings enhance our understanding of the biological processes of schizophrenia, enabling us to identify specific clinical dimensions of genes for diagnosis and prognostic markers and possibly for targeted therapy.

Transcriptome analysis of fibroblasts from schizophrenia patients reveals differential expression of schizophrenia-related genes

Schizophrenia is a complex neurodevelopmental disorder with high rate of morbidity and mortality. While the heritability rate is high, the precise etiology is still unknown. Although schizophrenia is a central nervous system disorder, studies using peripheral tissues have also been established to search for patient specific biomarkers and to increase understanding of schizophrenia etiology. Among all peripheral tissues, fibroblasts stand out as they are easy to obtain and culture. Furthermore, they keep genetic stability for long period and exhibit molecular similarities to cells from nervous system. Using a unique set of fibroblast samples from a genetically isolated population in northern Sweden, we performed whole transcriptome sequencing to compare differentially expressed genes in seven controls and nine patients. We found differential fibroblast expression between cases and controls for 48 genes, including eight genes previously implicated in schizophrenia or schizophrenia related pathways; HGF, PRRT2, EGR1, EGR3, C11orf87, TLR3, PLEKHH2 and PIK3CD. Weighted gene correlation network analysis identified three differentially co-expressed networks of genes significantly-associated with schizophrenia. All three modules were significantly suppressed in patients compared to control, with one module highly enriched in genes involved in synaptic plasticity, behavior and synaptic transmission. In conclusion, our results support the use of fibroblasts for identification of differentially expressed genes in schizophrenia and highlight dysregulation of synaptic networks as an important mechanism in schizophrenia.

Influence of EGR3 Transfection on Imaging and Behavior in Rats and Therapeutic Effect of Risperidone in Schizophrenia Model

Schizophrenia is a type of neurodevelopmental psychiatric disorder. However, to date, scientists have not discovered the etiology and effective treatment of this condition. We injected the early growth response gene (EGR3) into the bilateral hippocampus to build a schizophrenia rat model. Behavioral phenotyping and resting-state functional magnetic resonance imaging (rs-fMRI) were used to analyze the behavioral and cerebral alterations in the schizophrenia rat model. The efficacy of risperidone therapy was also evaluated. We divided 34 rats into four groups: schizophrenia model group (E group), sham-operation group (FE group), healthy control group (H group), and risperidone therapy group (T group). Open field test and Morris water maze were conducted as behavioral experiments. Next, we performed rs-fMRI after four weeks of EGR3 transfection and risperidone treatment and analyzed imaging data using regional homogeneity (ReHo), the amplitude of low-frequency fluctuations (ALFF), and functional connectivity (FC). We examined the difference in behavioral and neural activation among the four groups and considered the correlations between behavior and imaging results. EGR3 gene transfection decreased the total moved distance in the open field test and the duration in the Q5 zone of the Morris water maze. Risperidone treatment reversed the trend and improved the performance of rats in these behavioral tests. Schizophrenia induced several neural alterations in ALFF and ReHo metrics of the rat brain, and risperidone could partly reverse these alterations. The results suggest that similar research is required for schizophrenia and that risperidone may be a novel treatment for dysregulated neural activation in schizophrenia.

Gene Regulatory Network of Dorsolateral Prefrontal Cortex: a Master Regulator Analysis of Major Psychiatric Disorders

Despite the strong genetic component of psychiatric disorders, traditional genetic studies have failed to find individual genes of large effect size. Thus, alternative methods, using bioinformatics, have been proposed to solve these biological puzzles. Of these, here we employ systems biology-based approaches to identify potential master regulators (MRs) of bipolar disorder (BD), schizophrenia (SZ), and major depressive disorder (MDD), their association with biological processes and their capacity to differentiate disorders' phenotypes. High-throughput gene expression data was used to reconstruct standard human dorsolateral prefrontal cortex regulatory transcriptional network, which was then queried for regulatory units and MRs associated with the psychiatric disorders of interest. Furthermore, the activity status (active or repressed) of MR candidates was obtained and used in cluster analysis to characterize disease phenotypes. Finally, we explored the biological processes modulated by the MRs using functional enrichment analysis. Thirty-one, thirty-four, and fifteen MR candidates were identified in BD, SZ, and MDD, respectively. The activity state of these MRs grouped the illnesses in three clusters: MDD only, mostly BD, and a third one with BD and SZ. While BD and SZ share several biological processes related to ion transport and homeostasis, synapse, and immune function, SZ showed peculiar enrichment of processes related to cytoskeleton and neuronal structure. Meanwhile, MDD presented mostly processes related to glial development and fatty acid metabolism. Our findings suggest notable differences in functional enrichment between MDD and BD/SZ. Furthermore, similarities between BD and SZ may impose particular challenges in attempts to discriminate these pathologies based solely on their transcriptional profiles. Nevertheless, we believe that systems-oriented approaches are promising strategies to unravel the pathophysiology peculiarities underlying mental illnesses and reveal therapeutic targets.

Functional analyses and effect of DNA methylation on the EGR1 gene in patients with schizophrenia

EGR1, involved in the regulation of synaptic plasticity, learning, and memory, is considered a candidate gene for schizophrenia. We resequenced the exonic regions of EGR1 in 516 patients with schizophrenia and conducted a reporter gene assay. We found two mutations including a rare mutation (c.-8C>T, rs561524195) and one common SNP (c.308-42C>T, rs11743810). The reporter gene assay showed c.-8C>T mutant did not affect promoter activity. Gene expression analyses showed that the average EGR1 mRNA and protein levels in lymphoblastoid cell lines of schizophrenia in male, but not female, were significantly higher than those in controls. We conducted in vitro DNA methylation reaction, luciferase activity assay, and pyrosequencing to assess DNA methylation of EGR1 expression underlying the pathophysiology of schizophrenia. DNA methylation of the EGR1 promoter region attenuated reporter activity, suggesting that DNA methylation regulates EGR1 expression. There were no statistically significant differences in DNA methylation levels of 17 CpG sites at the EGR1 promoter region between 64 patients with schizophrenia compared with 64 controls. These results suggest that the exonic mutations in EGR1 and DNA methylation regulating EGR1 expression might not be associated with schizophrenia. However, the gender-specific association of elevated EGR1 expression might be involved in the pathophysiology of schizophrenia.

PET neuroimaging reveals histone deacetylase dysregulation in schizophrenia

BACKGROUND

Patients with schizophrenia (SCZ) experience chronic cognitive deficits. Histone deacetylases (HDACs) are enzymes that regulate cognitive circuitry; however, the role of HDACs in cognitive disorders, including SCZ, remains unknown in humans. We previously determined that HDAC2 mRNA levels were lower in dorsolateral prefrontal cortex (DLPFC) tissue from donors with SCZ compared with controls. Here we investigated the relationship between in vivo HDAC expression and cognitive impairment in patients with SCZ and matched healthy controls using [11C]Martinostat positron emission tomography (PET).

METHODS

In a case-control study, relative [11C]Martinostat uptake was compared between 14 patients with SCZ or schizoaffective disorder (SCZ/SAD) and 17 controls using hypothesis-driven region-of-interest analysis and unbiased whole brain voxel-wise approaches. Clinical measures, including the MATRICS consensus cognitive battery, were administered.

RESULTS

Relative HDAC expression was lower in the DLPFC of patients with SCZ/SAD compared with controls, and HDAC expression positively correlated with cognitive performance scores across groups. Patients with SCZ/SAD also showed lower relative HDAC expression in the dorsomedial prefrontal cortex and orbitofrontal gyrus, and higher relative HDAC expression in the cerebral white matter, pons, and cerebellum compared with controls.

CONCLUSIONS

These findings provide in vivo evidence of HDAC dysregulation in patients with SCZ and suggest that altered HDAC expression may impact cognitive function in humans.

FUNDING

National Institute of Mental Health (NIMH), Brain and Behavior Foundation, Massachusetts General Hospital (MGH), Athinoula A. Martinos Center for Biomedical Imaging, National Institute of Biomedical Imaging and Bioengineering (NIBIB), NIH Shared Instrumentation Grant Program.

Influence of Schizophrenia-Associated Gene Egr3 on Sleep Behavior and Circadian Rhythms in Mice

Up to 80% of people meeting DSM-IV definitions for schizophrenia will exhibit difficulties with sleep, along with a breakdown in circadian entrainment and rhythmicity. The changes to the sleep and circadian systems in this population are thought to be interdependent, as evidenced by the frequent use of the combined term "sleep and circadian rhythm disruption" or "SCRD" to describe their occurrence. To understand links between sleep and circadian problems in the schizophrenia population, we analyzed the duration and rhythmicity of sleep behavior in mice lacking function of the immediate early gene early growth response 3 ( Egr3). EGR3 has been associated with schizophrenia risk in humans, and Egr3-deficient (-/-) mice display various features of schizophrenia that are responsive to antipsychotic treatment. While Egr3-/- mice slept less than their wildtype (WT) littermates, they showed no evidence of circadian disorganization; in fact, circadian rhythms of activity were more robust in these mice compared with WT, as measured by time series analysis and the relative amplitude index of Van Someren's suite of non-parametric circadian rhythm analyses. Differences in circadian robustness were maintained when the animals were transferred to several weeks of housing under constant darkness or constant light. Together, our results suggest that Egr3-/- mice retain control over the circadian timekeeping of sleep and wake, while showing impaired sleep. The findings are compatible with those from a surprising array of mouse models of schizophrenia and raise the possibility that SCRD may be 2 separate disorders in the schizophrenia population requiring different treatment strategies.

State-Dependent Modulation of Visual Evoked Potentials in a Rodent Genetic Model of Electroencephalographic Instability

Despite normal sleep timing and duration, Egr3-deficient (Egr3^−/−) mice exhibit electroencephalographic (EEG) characteristics of reduced arousal, including elevated slow wave (1–4 Hz) activity during wakefulness. Here we show that these mice exhibit state-dependent instability in the EEG. Intermittent surges in EEG power were found in Egr3^−/− mice during wakefulness and rapid eye movement sleep, most prominently in the beta (15–35 Hz) range compared to wild type (Egr3^+/+) mice. Such surges did not coincide with sleep onset, as the surges were not associated with cessation of electromyographic tone. Cortical processing of sensory information by visual evoked responses (VEP) were found to vary as a function of vigilance state, being of higher magnitude during slow wave sleep (SWS) than wakefulness and rapid eye movement sleep. VEP responses were significantly larger during quiet wakefulness than active wakefulness, in both Egr3^−/− mice and Egr3^+/+ mice. EEG synchronization in the beta range, previously linked to the accumulation of sleep need over time, predicted VEP magnitude. Egr3^−/− mice not only displayed elevated beta activity, but in quiet wake, this elevated beta activity coincides with an elevated evoked response similar to that of animals in SWS. These data confirm that (a) VEPs vary as a function of vigilance state, and (b) beta activity in the EEG is a predictor of state-dependent modulation of visual information processing. The phenotype of Egr3^−/− mice indicates that Egr3 is a genetic regulator of these phenomena.

Neurobiology and consequences of social isolation stress in animal model-A comprehensive review

The brain is a vital organ, susceptible to alterations under genetic influences and environmental experiences. Social isolation (SI) acts as a stressor which results in alterations in reactivity to stress, social behavior, function of neurochemical and neuroendocrine system, physiological, anatomical and behavioral changes in both animal and humans. During early stages of life, acute or chronic SIS has been proposed to show signs and symptoms of psychiatric and neurological disorders such as anxiety, depression, schizophrenia, epilepsy and memory loss. Exposure to social isolation stress induces a variety of endocrinological changes including the activation of hypothalamic-pituitary-adrenal (HPA) axis, culminating in the release of glucocorticoids (GCs), release of catecholamines, activation of the sympatho-adrenomedullary system, release of Oxytocin and vasopressin. In several regions of the central nervous system (CNS), SIS alters the level of neurotransmitter such as dopamine, serotonin, gamma aminobutyric acid (GABA), glutamate, nitrergic system and adrenaline as well as leads to alteration in receptor sensitivity of N-methyl-D-aspartate (NMDA) and opioid system. A change in the function of oxidative and nitrosative stress (O&NS) mediated mitochondrial dysfunction, inflammatory factors, neurotrophins and neurotrophicfactors (NTFs), early growth response transcription factor genes (Egr) and C-Fos expression are also involved as a pathophysiological consequences of SIS which induce neurological and psychiatric disorders.

The Immediate Early Gene Egr3 Is Required for Hippocampal Induction of Bdnf by Electroconvulsive Stimulation

Early growth response 3 (Egr3) is an immediate early gene (IEG) that is regulated downstream of a cascade of genes associated with risk for psychiatric disorders, and dysfunction of Egr3 itself has been implicated in schizophrenia, bipolar disorder, and depression. As an activity-dependent transcription factor, EGR3 is poised to regulate the neuronal expression of target genes in response to environmental events. In the current study, we sought to identify a downstream target of EGR3 with the goal of further elucidating genes in this biological pathway relevant for psychiatric illness risk. We used electroconvulsive stimulation (ECS) to induce high-level expression of IEGs in the brain, and conducted expression microarray to identify genes differentially regulated in the hippocampus of Egr3-deficient (-/-) mice compared to their wildtype (WT) littermates. Our results replicated previous work showing that ECS induces high-level expression of the brain-derived neurotrophic factor (Bdnf) in the hippocampus of WT mice. However, we found that this induction is absent in Egr3-/- mice. Quantitative real-time PCR (qRT-PCR) validated the microarray results (performed in males) and replicated the findings in two separate cohorts of female mice. Follow-up studies of activity-dependent Bdnf exons demonstrated that ECS-induced expression of both exons IV and VI requires Egr3. In situ hybridization demonstrated high-level cellular expression of Bdnf in the hippocampal dentate gyrus following ECS in WT, but not Egr3-/-, mice. Bdnf promoter analysis revealed eight putative EGR3 binding sites in the Bdnf promoter, suggesting a mechanism through which EGR3 may directly regulate Bdnf gene expression. These findings do not appear to result from a defect in the development of hippocampal neurons in Egr3-/- mice, as cell counts in tissue sections stained with anti-NeuN antibodies, a neuron-specific marker, did not differ between Egr3-/- and WT mice. In addition, Sholl analysis and counts of dendritic spines in golgi-stained hippocampal sections revealed no difference in dendritic morphology or synaptic spine density in Egr3-/-, compared to WT, mice. These findings indicate that Egr3 is required for ECS-induced expression of Bdnf in the hippocampus and suggest that Bdnf may be a downstream gene in our previously identified biologically pathway for psychiatric illness susceptibility.

Immediate Early Genes, Memory and Psychiatric Disorders: Focus on c-Fos, Egr1 and Arc

Many psychiatric disorders, despite their specific characteristics, share deficits in the cognitive domain including executive functions, emotional control and memory. However, memory deficits have been in many cases undervalued compared with other characteristics. The expression of Immediate Early Genes (IEGs) such as, c-fos, Egr1 and arc are selectively and promptly upregulated in learning and memory among neuronal subpopulations in regions associated with these processes. Changes in expression in these genes have been observed in recognition, working and fear related memories across the brain. Despite the enormous amount of data supporting changes in their expression during learning and memory and the importance of those cognitive processes in psychiatric conditions, there are very few studies analyzing the direct implication of the IEGs in mental illnesses. In this review, we discuss the role of some of the most relevant IEGs in relation with memory processes affected in psychiatric conditions.

Immediate Early Genes Anchor a Biological Pathway of Proteins Required for Memory Formation, Long-Term Depression and Risk for Schizophrenia

While the causes of myriad medical and infectious illnesses have been identified, the etiologies of neuropsychiatric illnesses remain elusive. This is due to two major obstacles. First, the risk for neuropsychiatric disorders, such as schizophrenia, is determined by both genetic and environmental factors. Second, numerous genes influence susceptibility for these illnesses. Genome-wide association studies have identified at least 108 genomic loci for schizophrenia, and more are expected to be published shortly. In addition, numerous biological processes contribute to the neuropathology underlying schizophrenia. These include immune dysfunction, synaptic and myelination deficits, vascular abnormalities, growth factor disruption, and N-methyl-D-aspartate receptor (NMDAR) hypofunction. However, the field of psychiatric genetics lacks a unifying model to explain how environment may interact with numerous genes to influence these various biological processes and cause schizophrenia. Here we describe a biological cascade of proteins that are activated in response to environmental stimuli such as stress, a schizophrenia risk factor. The central proteins in this pathway are critical mediators of memory formation and a particular form of hippocampal synaptic plasticity, long-term depression (LTD). Each of these proteins is also implicated in schizophrenia risk. In fact, the pathway includes four genes that map to the 108 loci associated with schizophrenia: GRIN2A, nuclear factor of activated T-cells (NFATc3), early growth response 1 (EGR1) and NGFI-A Binding Protein 2 (NAB2); each of which contains the "Index single nucleotide polymorphism (SNP)" (most SNP) at its respective locus. Environmental stimuli activate this biological pathway in neurons, resulting in induction of EGR immediate early genes: EGR1, EGR3 and NAB2. We hypothesize that dysfunction in any of the genes in this pathway disrupts the normal activation of Egrs in response to stress. This may result in insufficient electrophysiologic, immunologic, and neuroprotective, processes that these genes normally mediate. Continued adverse environmental experiences, over time, may thereby result in neuropathology that gives rise to the symptoms of schizophrenia. By combining multiple genes associated with schizophrenia susceptibility, in a functional cascade triggered by neuronal activity, the proposed biological pathway provides an explanation for both the polygenic and environmental influences that determine the complex etiology of this mental illness.

Calcineurin knockout mice show a selective loss of small spines

Calcineurin is required for long-term depression and activity-dependent spine shrinkage, and calcineurin mutations have been identified in patients with schizophrenia. Moreover, mice with conditional knockout of calcineurin B (CNB-KO) exhibit behavioral abnormalities suggestive of schizophrenia. Changes in the dendritic spines of these mice, however, have not been investigated. We therefore examined the dendritic spines of CNB-KO mice, and observed a significant reduction in small spines and an increase in large spines in the prefrontal and visual cortices. The effect of CNB-KO on the spine sizes was relatively moderate, possibly due to the presence of spontaneous fluctuations (dynamics) in the dendritic spines themselves. Thus, CNB-KO mice showed a spine phenotype similar to those recently reported in patients with schizophrenia.

EGR3 Immediate Early Gene and the Brain-Derived Neurotrophic Factor in Bipolar Disorder

Bipolar disorder (BD) is a severe psychiatric illness with a consistent genetic influence, involving complex interactions between numerous genes and environmental factors. Immediate early genes (IEGs) are activated in the brain in response to environmental stimuli, such as stress. The potential to translate environmental stimuli into long-term changes in brain has led to increased interest in a potential role for these genes influencing risk for psychiatric disorders. Our recent finding using network-based approach has shown that the regulatory unit of early growth response gene 3 (EGR3) of IEGs family was robustly repressed in postmortem prefrontal cortex of BD patients. As a central transcription factor, EGR3 regulates an array of target genes that mediate critical neurobiological processes such as synaptic plasticity, memory and cognition. Considering that EGR3 expression is induced by brain-derived neurotrophic factor (BDNF) that has been consistently related to BD pathophysiology, we suggest a link between BDNF and EGR3 and their potential role in BD. A growing body of data from our group and others has shown that peripheral BDNF levels are reduced during mood episodes and also with illness progression. In this same vein, BDNF has been proposed as an important growth factor in the impaired cellular resilience related to BD. Taken together with the fact that EGR3 regulates the expression of the neurotrophin receptor p75NTR and may also indirectly induce BDNF expression, here we propose a feed-forward gene regulatory network involving EGR3 and BDNF and its potential role in BD.

Comparative Analysis of Gene Expression Profiles Involved in Calcium Signaling Pathways Using the NLVH Animal Model of Schizophrenia

In this study, we evaluated the expression profile changes of genes that intervene in the calcium signaling pathway, in young and adult Wistar rats, using the animal model of neonatal lesion in ventral hippocampus (NLVH) (a recognized animal model for schizophrenia) and compared to the group of control animals (Sham). Through microarray technology, gene expression profiles were obtained from the three brain areas (nucleus accumbens, prefrontal cortex, and hippocampus) of young male Wistar rats (45 days) and adults (90 days) whether or not subjected to NLVH. The calcium signaling pathway reported a greater number of differentially expressed genes with z-score two values, > 2 (over-expression) and < - 2 (under-expression), in the three evaluated areas. The comparative analyses of this approach were performed in juvenile and adult rats with ventral hippocampal lesion in neonate rats (NLVH). NLVH influenced change expressions in various genes involved in Ca²⁺ homeostasis, including Cacna1d, Atp2a2, Adcy2, Ppp3cb, and Ptk2b. The expression of Adcy2, Ppp3cb, and Ptk2b genes changed in both age groups; therefore, the study of gene expression profiles between juvenile and adult rats may help to understand the molecular mechanisms of schizophrenia.

Microarray gene-expression study in fibroblast and lymphoblastoid cell lines from antipsychotic-naïve first-episode schizophrenia patients

Schizophrenia (SZ) is a chronic psychiatric disorder whose onset of symptoms occurs in late adolescence and early adulthood. The etiology is complex and involves important gene-environment interactions. Microarray gene-expression studies on SZ have identified alterations in several biological processes. The heterogeneity in the results can be attributed to the use of different sample types and other important confounding factors including age, illness chronicity and antipsychotic exposure. The aim of the present microarray study was to analyze, for the first time to our knowledge, differences in gene expression profiles in 18 fibroblast (FCLs) and 14 lymphoblastoid cell lines (LCLs) from antipsychotic-naïve first-episode schizophrenia (FES) patients and healthy controls. We used an analytical approach based on protein-protein interaction network construction and functional annotation analysis to identify the biological processes that are altered in SZ. Significant differences in the expression of 32 genes were found when LCLs were assessed. The network and gene set enrichment approach revealed the involvement of similar biological processes in FCLs and LCLs, including apoptosis and related biological terms such as cell cycle, autophagy, cytoskeleton organization and response to stress and stimulus. Metabolism and other processes, including signal transduction, kinase activity and phosphorylation, were also identified. These results were replicated in two independent cohorts using the same analytical approach. This provides more evidence for altered apoptotic processes in antipsychotic-naïve FES patients and other important biological functions such as cytoskeleton organization and metabolism. The convergent results obtained in both peripheral cell models support their usefulness for transcriptome studies on SZ.

Adaptive and Behavioral Changes in Kynurenine 3-Monooxygenase Knockout Mice: Relevance to Psychotic Disorders

BACKGROUND

Kynurenine 3-monooxygenase converts kynurenine to 3-hydroxykynurenine, and its inhibition shunts the kynurenine pathway-which is implicated as dysfunctional in various psychiatric disorders-toward enhanced synthesis of kynurenic acid, an antagonist of both α7 nicotinic acetylcholine and N-methyl-D-aspartate receptors. Possibly as a result of reduced kynurenine 3-monooxygenase activity, elevated central nervous system levels of kynurenic acid have been found in patients with psychotic disorders, including schizophrenia.

METHODS

In the present study, we investigated adaptive-and possibly regulatory-changes in mice with a targeted deletion of Kmo (Kmo^-/-) and characterized the kynurenine 3-monooxygenase-deficient mice using six behavioral assays relevant for the study of schizophrenia.

RESULTS

Genome-wide differential gene expression analyses in the cerebral cortex and cerebellum of these mice identified a network of schizophrenia- and psychosis-related genes, with more pronounced alterations in cerebellar tissue. Kynurenic acid levels were also increased in these brain regions in Kmo^-/- mice, with significantly higher levels in the cerebellum than in the cerebrum. Kmo^-/- mice exhibited impairments in contextual memory and spent less time than did controls interacting with an unfamiliar mouse in a social interaction paradigm. The mutant animals displayed increased anxiety-like behavior in the elevated plus maze and in a light/dark box. After a D-amphetamine challenge (5 mg/kg, intraperitoneal), Kmo^-/- mice showed potentiated horizontal activity in the open field paradigm.

CONCLUSIONS

Taken together, these results demonstrate that the elimination of Kmo in mice is associated with multiple gene and functional alterations that appear to duplicate aspects of the psychopathology of several neuropsychiatric disorders.

Post-mortem molecular profiling of three psychiatric disorders

BACKGROUND

Psychiatric disorders are multigenic diseases with complex etiology that contribute significantly to human morbidity and mortality. Although clinically distinct, several disorders share many symptoms, suggesting common underlying molecular changes exist that may implicate important regulators of pathogenesis and provide new therapeutic targets.

METHODS

We performed RNA sequencing on tissue from the anterior cingulate cortex, dorsolateral prefrontal cortex, and nucleus accumbens from three groups of 24 patients each diagnosed with schizophrenia, bipolar disorder, or major depressive disorder, and from 24 control subjects. We identified differentially expressed genes and validated the results in an independent cohort. Anterior cingulate cortex samples were also subjected to metabolomic analysis. ChIP-seq data were used to characterize binding of the transcription factor EGR1.

RESULTS

We compared molecular signatures across the three brain regions and disorders in the transcriptomes of post-mortem human brain samples. The most significant disease-related differences were in the anterior cingulate cortex of schizophrenia samples compared to controls. Transcriptional changes were assessed in an independent cohort, revealing the transcription factor EGR1 as significantly down-regulated in both cohorts and as a potential regulator of broader transcription changes observed in schizophrenia patients. Additionally, broad down-regulation of genes specific to neurons and concordant up-regulation of genes specific to astrocytes was observed in schizophrenia and bipolar disorder patients relative to controls. Metabolomic profiling identified disruption of GABA levels in schizophrenia patients.

CONCLUSIONS

We provide a comprehensive post-mortem transcriptome profile of three psychiatric disorders across three brain regions. We highlight a high-confidence set of independently validated genes differentially expressed between schizophrenia and control patients in the anterior cingulate cortex and integrate transcriptional changes with untargeted metabolite profiling.

DNA methylation analysis of the EGR3 gene in patients of schizophrenia

DNA methylation has been implicated in the pathogenesis of schizophrenia. EGR3 is considered as a potential candidate gene for schizophrenia. We conducted in vitro DNA methylation reaction, Lucia luciferase activity assay, and pyrosequencing assay to assess the DNA methylation of the EGR3 expression underlying the pathophysiology of schizophrenia. We found that DNA methylation of the putative EGR3 regulatory regions attenuated Lucia luciferase activity. There was no difference in the DNA methylation pattern of EGR3 between in 50 schizophrenic patients and 47 controls. Our data suggest that DNA methylation regulated the expression of EGR3 might not be associated with schizophrenia.

Sansoninto, a traditional herbal medicine, ameliorates behavioral abnormalities and down-regulation of early growth response-1 expression in mice exposed to social isolation stress

Social isolation (SI) mice exhibit behavioral abnormalities such as impairments of sociability- and attention-like behaviors, offering an animal model of neurodevelopmental disorders such as attention-deficit/hyperactivity disorder (ADHD). This study aimed to identify the effects of Sansoninto (SST; 酸棗仁湯 suān zǎo rén tāng) on the psychiatric symptoms related to ADHD using SI mice. Four-week-old mice were socially isolated during the experimental period, and SST administration (800 or 2400 mg/kg, p.o.) was started at 2 weeks after starting SI. SST ameliorated SI-induced impairments of sociability- and attention-like behaviors in a dose-dependent manner, and tended to ameliorate contextual- and auditory-dependent fear memory deficit. Moreover, the expression level of Egr-1 was down-regulated by SI stress, and was restored by a high dose of SST. These findings suggest that SST is useful for improvement of psychiatric disorders such as ADHD.

The Role of Early Growth Response 1 (EGR1) in Brain Plasticity and Neuropsychiatric Disorders

It is now clearly established that complex interactions between genes and environment are involved in multiple aspects of neuropsychiatric disorders, from determining an individual's vulnerability to onset, to influencing its response to therapeutic intervention. In this perspective, it appears crucial to better understand how the organism reacts to environmental stimuli and provide a coordinated and adapted response. In the central nervous system, neuronal plasticity and neurotransmission are among the major processes integrating such complex interactions between genes and environmental stimuli. In particular, immediate early genes (IEGs) are critical components of these interactions as they provide the molecular framework for a rapid and dynamic response to neuronal activity while opening the possibility for a lasting and sustained adaptation through regulation of the expression of a wide range of genes. As a result, IEGs have been tightly associated with neuronal activity as well as a variety of higher order processes within the central nervous system such as learning, memory and sensitivity to reward. The immediate early gene and transcription factor early growth response 1 (EGR1) has thus been revealed as a major mediator and regulator of synaptic plasticity and neuronal activity in both physiological and pathological conditions. In this review article, we will focus on the role of EGR1 in the central nervous system. First, we will summarize the different factors influencing its activity. Then, we will analyze the amount of data, including genome-wide, that has emerged in the recent years describing the wide variety of genes, pathways and biological functions regulated directly or indirectly by EGR1. We will thus be able to gain better insights into the mechanisms underlying EGR1's functions in physiological neuronal activity. Finally, we will discuss and illustrate the role of EGR1 in pathological states with a particular interest in cognitive functions and neuropsychiatric disorders.