MicroRNA-9 and microRNA-326 regulate human dopamine D2 receptor expression, and the microRNA-mediated expression regulation is altered by a genetic variant

MicroRNA dysregulation in glutamate and dopamine pathways of schizophrenia: From molecular pathways to diagnostic and therapeutic approaches

Schizophrenia is a complex psychiatric disorder, and genetic and environmental factors have been implicated in its development. Dysregulated glutamatergic and dopaminergic transmission pathways are involved in schizophrenia development. Besides genetic mutations, epigenetic dysregulation has a considerable role in dysregulating molecular pathways involved in schizophrenia. MicroRNAs (miRNAs) are small, non-coding RNAs that target specific mRNAs and inhibit their translation into proteins. As epigenetic factors, miRNAs regulate many genes involved in glutamate and dopamine signaling pathways; thereby, their dysregulation can contribute to the development of schizophrenia. Secretion of specific miRNAs from damaged cells into body fluids can make them one of the ideal non-invasive biomarkers in the early diagnosis of schizophrenia. Also, understanding the molecular mechanisms of miRNAs in schizophrenia pathogenesis can pave the way for developing novel treatments for patients with schizophrenia. In this study, we reviewed the glutamatergic and dopaminergic pathophysiology and highlighted the role of miRNA dysregulation in schizophrenia development. Besides, we shed light on the significance of circulating miRNAs for schizophrenia diagnosis and the recent findings on the miRNA-based treatment for schizophrenia.

Identification of stress-induced epigenetic methylation onto dopamine D2 gene and neurological and behavioral consequences

The D2 dopamine receptor (DRD2) gene has garnered substantial attention as one of the most extensively studied genes across various neuropsychiatric disorders. Since its initial association with severe alcoholism in 1990, particularly through the identification of the DRD2 Taq A1 allele, numerous international investigations have been conducted to elucidate its role in different conditions. As of February 22, 2024, there are 5485 articles focusing on the DRD2 gene listed in PUBMED. There have been 120 meta-analyses with mixed results. In our opinion, the primary cause of negative reports regarding the association of various DRD2 gene polymorphisms is the inadequate screening of controls, not adequately eliminating many hidden reward deficiency syndrome behaviors. Moreover, pleiotropic effects of DRD2 variants have been identified in neuropsychologic, neurophysiologic, stress response, social stress defeat, maternal deprivation, and gambling disorder, with epigenetic DNA methylation and histone post-translational negative methylation identified as discussed in this article. There are 70 articles listed in PUBMED for DNA methylation and 20 articles listed for histone methylation as of October 19, 2022. For this commentary, we did not denote DNA and/or histone methylation; instead, we provided a brief summary based on behavioral effects. Based on the fact that Blum and Noble characterized the DRD2 Taq A1 allele as a generalized reward gene and not necessarily specific alcoholism, it now behooves the field to find ways to either use effector moieties to edit the neuroepigenetic insults or possibly harness the idea of potentially removing negative mRNA-reduced expression by inducing "dopamine homeostasis."

miR-9-5p deficiency contributes to schizophrenia

MicroRNA-9-5p (miR-9-5p) is highly expressed in the brain and has been implicated in the risk of schizophrenia. We compared the expression levels of miR-9-5p in schizophrenia cases and healthy controls and evaluated whether regulatory targets of miR-9-5p are enriched in schizophrenia genome-wide risk genes. Literature-based analysis was conducted to construct molecular pathways connecting miR-9-5p and schizophrenia. We found that the expression levels of miR-9-5p were down-regulated in the peripheral blood of schizophrenia patients compared with those in healthy controls. miR-9-5p can regulate 24 out of the 1136 genome-wide risk genes of schizophrenia, which was higher than by chance (hypergeometric test P = 4.09E-06). The literature-based analysis showed that quantitative genetic changes driven by miR-9 exert more inhibitory (the IL1B, ABCB1, FGFR1 genes) than promoting (the INS gene) effects on schizophrenia, suggesting that miR-9 may protect against schizophrenia. Our results suggest that miR-9-5p deficiency may contribute to the development of schizophrenia.

MicroRNAs as promising therapeutic agents: A perspective from acupuncture

MicroRNAs (miRNAs) are gaining recognition as potential therapeutic agents due to their small size, ability to target a wide range of genes, and significant role in disease progression. However, despite their promising potential, nearly half of the miRNA drugs developed for therapeutic purposes have been discontinued or put on hold, and none have advanced to phase III clinical trials. The development of miRNA therapeutics has faced obstacles such as difficulties in validating miRNA targets, conflicting evidence regarding competition and saturation effects, challenges in miRNA delivery, and determining appropriate dosages. These hurdles primarily arise from the intricate functional complexity of miRNAs. Acupuncture, a distinct, complementary therapy, offers a promising avenue to overcome these barriers, particularly by addressing the fundamental issue of preserving functional complexity through acupuncture regulatory networks. The acupuncture regulatory network consists of three main components: the acupoint network, the neuro-endocrine-immune (NEI) network, and the disease network. These networks represent the processes of information transformation, amplification, and conduction that occur during acupuncture. Notably, miRNAs serve as essential mediators and shared biological language within these interconnected networks. Harnessing the therapeutic potential of acupuncture-derived miRNAs can help reduce the time and economic resources required for miRNA drug development and alleviate the current developmental challenges miRNA therapeutics face. This review provides an interdisciplinary perspective by summarizing the interactions between miRNAs, their targets, and the three acupuncture regulatory networks mentioned earlier. The aim is to illuminate the challenges and opportunities in developing miRNA therapeutics. This review paper presents a comprehensive overview of miRNAs, their interactions with acupuncture regulatory networks, and their potential as therapeutic agents. By bridging the miRNA research and acupuncture fields, we aim to offer valuable insights into the obstacles and prospects of developing miRNA therapeutics.

MicroRNA schizophrenia: Etiology, biomarkers and therapeutic targets

The three sets of symptoms associated with schizophrenia-positive, negative, and cognitive-are burdensome and have serious effects on public health, which affects up to 1% of the population. It is now commonly believed that in addition to the traditional dopaminergic mesolimbic pathway, the etiology of schizophrenia also includes neuronal networks, such as glutamate, GABA, serotonin, BDNF, oxidative stress, inflammation and the immune system. Small noncoding RNA molecules called microRNAs (miRNAs) have come to light as possible participants in the pathophysiology of schizophrenia in recent years by having an impact on these systems. These small RNAs regulate the stability and translation of hundreds of target transcripts, which has an impact on the entire gene network. There may be improved approaches to treat and diagnose schizophrenia if it is understood how these changes in miRNAs alter the critical related signaling pathways that drive the development and progression of the illness.

MicroRNAs and Synaptic Plasticity: From Their Molecular Roles to Response to Therapy

Synaptic plasticity is the ability of synapses to weaken or strengthen over time, in response to changes in the activity of the neurons. It is orchestrated by a variety of genes, proteins, and external and internal factors, especially epigenetic factors. MicroRNAs (miRNAs) are well-acknowledged epigenetic modulators that regulate the translation and degradation of target genes in the nervous system. Increasing evidence has suggested that a number of miRNAs play important roles in modulating various aspects of synaptic plasticity. The deregulation of miRNAs could be associated with pathological alterations in synaptic plasticity, which could lead to different CNS-related diseases. Herein, we provide an update on the role of miRNAs in governing synaptic plasticity. In addition, we also summarize recent researches on the role of miRNAs in drug addiction, and their targets and mechanism of action. Understanding of the way in which miRNAs contribute to synaptic plasticity provides rational clues in establishing the novel biomarkers and new therapeutic strategies for the diagnosis and treatment of plasticity-related diseases and drug addiction.

The value of the MicroRNAs on alcoholic addicts: A meta-analytic review

INTRODUCTION

A growing body of evidence indicates that repeated alcohol exposure or withdrawal from alcohol can result in persistent molecular and cellular adaptations. One molecular adaptation that occurs is the regulation of gene expression, which is believed to lead to functional alterations that characterize addiction. MicroRNAs (miRs) have been recently identified as master regulators of gene expression through post-transcriptional regulation. The aim of this meta-analytic review was to evaluate the regulatory forms of miRs during alcoholism.

METHODS

We used several databases such as PubMed, Scopus, and Web of Science without limitations on publication time. All studies were analyzed by Comprehensive Meta-Analysis software.

RESULTS AND DISCUSSION

Six clinical papers with 243 alcoholic patients and 162 controls were included. In this study, 1680 articles were initially reviewed and eventually, six clinical studies were included in the meta-analysis. The results of the meta-analysis showed that according to the random model, the difference between the upregulation and downregulation of central addiction targets was statistically significant, indicating that most dopamine- or gamma-aminobutyric acid receptor subunit (GABA)-related miRs are upregulated in alcoholics (P: 0.00, CI: 0.149-0.439).

CONCLUSION

This study strongly suggests that dopamine- or GABA-related miRs were mostly upregulated in alcoholism. Our findings revealed that about 9% of miRs were downregulated in alcoholism, including miR-567, miR-126, miR-1, miR-432, and miR-153. To identify other or specific miRs as potential biomarkers in alcoholics, large-scale studies and more clinical work are required.

MicroRNAs in Dopamine Agonist-Resistant Prolactinoma

Dopamine agonists (DAs) are preferred for the treatment of prolactinomas and are usually very effective. Nonetheless, 20-30% of bromocriptine- and approximately 10% of cabergoline-treated individuals exhibit resistance to DAs. In addition, the mechanism underlying this phenomenon remains elusive. In this study, we summarize the major findings regarding the role of microRNAs (miRNAs) in the pathogenesis of DA-resistant prolactinoma (DARP). Currently available evidence suggests that miRNAs are usually dysregulated in DARP and that, although controversial, the dysregulated miRNAs target the transforming growth factor (TGF)-β, dopamine 2 receptor (D2R), or estradiol (E2)/estrogen receptor (ER) signaling pathways to mediate the therapeutic effect of DAs. These findings provide new incentives for research on innovative strategies for predicting patients' responsiveness to dopamine therapies and for developing treatment approaches. Unfortunately, recent studies tended to focus exclusively on the differential miRNA expression profiles between DARP and dopamine-sensitive prolactinoma, and no definitive consensus has been reached regarding the role of these miRNAs in the modulation mechanism. Therefore, current and future efforts should be directed toward the exploration of the mechanism underlying the dysregulation of miRNAs as well as of the target proteins that are affected by the dysregulated miRNAs. Furthermore, the modulation of the expression of dysregulated miRNAs, which target the D2R, TGF-β, or E2/ER signaling pathways, might be a promising alternative to treat patients with DARP and improve their prognosis.

Cell type-specific and cross-population polygenic risk score analyses of MIR137 gene pathway in schizophrenia

Cell type-specific pathway-based polygenic risk scores (PRSs) may better inform disease biology and improve the precision of PRS-based clinical prediction. For microRNA-137 (MIR137), a leading neuropsychiatric risk gene and a post-transcriptional master regulator, we conducted a cell type-specific gene set PRS analysis in both European and Han Chinese schizophrenia (SZ) samples. We found that the PRS of neuronal MIR137-target genes better explains SZ risk than PRS derived from MIR137-target genes in iPSC or from the reported gene sets showing MIR137-altered expression. Compared with the PRS derived from the whole genome or the target genes of TCF4, the PRS of neuronal MIR137-target genes explained a disproportionally larger (relative to SNP number) SZ risk in the European sample, but with a more modest advantage in the Han Chinese sample. Our study demonstrated a cell type-specific polygenic contribution of MIR137-target genes to SZ risk, highlighting the value of cell type-specific pathway-based PRS analysis for uncovering disease-relevant biological features.

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PRS of neural MIR137 target genes better explains schizophrenia (SZ) risk variance

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SZ risk and SNP heritability explained by MIR137 target genes is cell type-specific

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MIR137 target genes explain a disproportionally larger SZ risk than genomic control

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PRS of MIR137 target genes better explains SZ risk in Europeans than in Han Chinese

Role of microRNAs in the pathophysiology of addiction

Addiction is a chronic and relapsing brain disorder characterized by compulsive seeking despite adverse consequences. There are both heritable and epigenetic mechanisms underlying drug addiction. Emerging evidence suggests that non-coding RNAs (ncRNAs) such as microRNAs (miRNAs), long non-coding RNAs, and circular RNAs regulate synaptic plasticity and related behaviors caused by substances of abuse. These ncRNAs modify gene expression and may contribute to the behavioral phenotypes of addiction. Among the ncRNAs, the most widely researched and impactful are miRNAs. The goal in this systematic review is to provide a detailed account of recent research involving the role of miRNAs in addiction. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Small Molecule-RNA Interactions RNA in Disease and Development > RNA in Disease.

MicroRNAs in β-thalassemia

β-thalassemia is a lethal inherited disease resulting from β-globin gene mutations. Severe β-thalassemia requires regular blood transfusions. Other active interventions, including iron chelating, stem cell transplantation and gene therapy, have remarkably improved the quality of life and prolonged the survival of patients with transfusion-dependent β-thalassemia, but all with significant limitations and complications. MicroRNAs (miRNAs), encoded by a class of endogenous genes, are found to play important roles in regulating globin expression. Among the miRNAs of particular interest related to β-thalassemia, miR-15a/16-1, miR-486-3p, miR-26b, miR-199b-5p, miR-210, miR-34a, miR-138, miR-326, let-7, and miR-17/92 cluster elevate γ-globin expression, while miR-96, miR-146a, miR-223-3p, and miR-144 inhibit γ-globin expression. A couple of miRNAs, miR-144 and miR-150, repress α-globin expression, whereas miR-451 induces α-, β- and γ-globin expression. Single nucleotide polymorphism in miRNA genes or their targeted genes might also contribute to the abnormal expression of hemoglobin. Moreover, changes in the expression of miR-125b, miR-210, miR-451, and miR-609 reflect the severity of anemia and hemolysis in β-thalassemia patients. These results suggest that miRNAs are potential biomarkers for the diagnosis and prognosis of β-thalassemia, and miRNA-based therapeutic strategy might be used as a coordinated approach for effectively treating β-thalassemia.

MicroRNA-15a, microRNA-15b and microRNA-16 inhibit the human dopamine D1 receptor expression in four cell lines by targeting 3'UTR -12 bp to + 154 bp

Background: The abnormal expression Dopamine D1 receptor (DRD1) gives rise to the dysfunction of dopaminergic neurotransmitter and may be associated with the occurrence of schizophrenia. MicroRNAs (miRNAs) can regulate the DRD1 expression by binding 3'UTR and be involved in the post-transcriptional regulation.Methods: We first constructed the pmirGLO-recombined vectors of series of DRD1 gene 3'UTR-truncated fragments and performed the luciferase receptor assay to screen the underlying 3'UTR sequence targeted by miRNAs. Then, we predicted the potential miRNAs binding the target sequence and confirmed their effects using luciferase receptor assay after transfection of the miRNA mimics/inhibitors. We also examined the effects of the miRNA on the endogenous DRD1 expression.Results: We found that the DRD1 3'UTR ranging from -12 to +1135 bp was essential for the post-transcriptional regulation of miRNAs. The deletion of -12 to +154 bp fragment significantly increased the luciferase expression but not the mRNA expression. The miRNA-15a, miRNA-15b and miRNA 16 affected DRD1 expression in HEK293, U87, SK-N-SH and SH-SY5Y cell lines.Conclusion: The miRNA-15a, miRNA-15b and miRNA-16 inhibit the human dopamine D1 receptor expression by targeting 3'UTR -12 to +154 bp.HighlightsDRD1 3'UTR ranging from -12 to +1135 bp was essential for the post-transcriptional regulation of miRNAs.The deletion of -12 to +154 bp fragment significantly increased the luciferase expression but not the mRNA expression.The miRNA-15a, miRNA-15b and miRNA 16 affected DRD1 expression in different cell lines, respectively.

Noncoding RNAs and Midbrain DA Neurons: Novel Molecular Mechanisms and Therapeutic Targets in Health and Disease

Midbrain dopamine neurons have crucial functions in motor and emotional control and their degeneration leads to several neurological dysfunctions such as Parkinson's disease, addiction, depression, schizophrenia, and others. Despite advances in the understanding of specific altered proteins and coding genes, little is known about cumulative changes in the transcriptional landscape of noncoding genes in midbrain dopamine neurons. Noncoding RNAs-specifically microRNAs and long noncoding RNAs-are emerging as crucial post-transcriptional regulators of gene expression in the brain. The identification of noncoding RNA networks underlying all stages of dopamine neuron development and plasticity is an essential step to deeply understand their physiological role and also their involvement in the etiology of dopaminergic diseases. Here, we provide an update about noncoding RNAs involved in dopaminergic development and metabolism, and the related evidence of these biomolecules for applications in potential treatments for dopaminergic neurodegeneration.

Early Life Stress and the Onset of Obesity: Proof of MicroRNAs' Involvement Through Modulation of Serotonin and Dopamine Systems' Homeostasis

Healthy persons hold a very complex system for controlling energy homeostasis. The system functions on the interconnected way between the nutritional, endocrine, neural, and epigenetic regulation, which includes the microRNAs (miRNAs). Currently, it is well accepted that experiences of early life stress (ELS) carry modification of the central control of feeding behavior, one of the factors controlling energy homeostasis. Recently, studies give us a clue on the modulation of eating behavior, which is one of the main factors associated with the development of obesity. This clue connected the neural control through the serotonin (5HT) and dopamine (DA) systems with the fine regulation of miRNAs. The first pieces of evidence highlight the presence of the miR-16 in the regulation of the serotonin transporter (SERT) as well as the receptors 1a (5HT1A) and 2a (5HT2A). On the other hand, miR-504 is related to the dopamine receptor D2 (DRD2). As our knowledge advance, we expected to discover other important pathways for the regulation of the energy homeostasis. As both neurotransmission systems and miRNAs seem to be sensible to ELS, the aim of this review is to bring new insight about the involvement of miRNAs with a central role in the control of eating behavior focusing on the influences of ELS and regulation of neurotransmission systems.

Dopamine Receptor Subtypes, Physiology and Pharmacology: New Ligands and Concepts in Schizophrenia

Dopamine receptors are widely distributed within the brain where they play critical modulator roles on motor functions, motivation and drive, as well as cognition. The identification of five genes coding for different dopamine receptor subtypes, pharmacologically grouped as D1- (D1 and D5) or D2-like (D2S, D2L, D3, and D4) has allowed the demonstration of differential receptor function in specific neurocircuits. Recent observation on dopamine receptor signaling point at dopamine-glutamate-NMDA neurobiology as the most relevant in schizophrenia and for the development of new therapies. Progress in the chemistry of D1- and D2-like receptor ligands (agonists, antagonists, and partial agonists) has provided more selective compounds possibly able to target the dopamine receptors homo and heterodimers and address different schizophrenia symptoms. Moreover, an extensive evaluation of the functional effect of these agents on dopamine receptor coupling and intracellular signaling highlights important differences that could also result in highly differentiated clinical pharmacology. The review summarizes the recent advances in the field, addressing the relevance of emerging new targets in schizophrenia in particular in relation to the dopamine - glutamate NMDA systems interactions.

Investigation of Schizophrenia with Human Induced Pluripotent Stem Cells

Schizophrenia is a chronic and severe neuropsychiatric condition manifested by cognitive, emotional, affective, perceptual, and behavioral abnormalities. Despite decades of research, the biological substrates driving the signs and symptoms of the disorder remain elusive, thus hampering progress in the development of treatments aimed at disease etiologies. The recent emergence of human induced pluripotent stem cell (hiPSC)-based models has provided the field with a highly innovative approach to generate, study, and manipulate living neural tissue derived from patients, making possible the exploration of fundamental roles of genes and early-life stressors in disease-relevant cell types. Here, we begin with a brief overview of the clinical, epidemiological, and genetic aspects of the condition, with a focus on schizophrenia as a neurodevelopmental disorder. We then highlight relevant technical advancements in hiPSC models and assess novel findings attained using hiPSC-based approaches and their implications for disease biology and treatment innovation. We close with a critical appraisal of the developments necessary for both further expanding knowledge of schizophrenia and the translation of new insights into therapeutic innovations.

Phosphoinositide-3-kinase regulatory subunit 1 gene polymorphisms are associated with schizophrenia and bipolar disorder in the Han Chinese population

Schizophrenia (SCZ) and bipolar disorder (BD) are severe psychiatric disorders that share many genetic risk factors. This study aimed to investigate the association of phosphoinositide-3-kinase regulatory subunit1 (PIK3R1) gene rs3756668 and rs3730089 polymorphisms with SCZ and BD risks and determine the expression levels of PIK3R1. A total of 548 SCZ cases, 512 BD cases, and 598 healthy controls were included in this study. Single nucleotide polymorphisms (SNPs) were genotyped using the Sequenom MassARRAY platform, and quantitative reverse transcription polymerase chain reaction was conducted to examine the mRNA expression of PIK3R1. The genotypic distribution of rs3756668 in the BD group was significantly different from that in the healthy controls (P = 0.038). After adjustment for gender and age was made, rs3730089 was significantly associated with the risk of SCZ [AA/(AG + GG): OR = 2.25, P_adj = 0.040; AA/GG: OR = 2.27, P_adj = 0.038]. The SNP rs3756668 was associated with the susceptibility of BD (AA+GG/AG: OR = 0.73, P = 0.011) and the association remained after adjusting for gender and age. The mRNA level of PIK3R1 was significantly upregulated in patients with BD compared with that in the control group (P < 0.001). In terms of the diagnostic value of PIK3R1 for BD, the receiver operating characteristic curve analysis showed an area under the curve of 0.809 with 74.0% sensitivity and 73.9% specificity. PIK3R1 may be the shared susceptibility gene of SCZ and BD and may be a potential diagnostic biomarker for BD.

Identification of rare and common variants in BNIP3L: a schizophrenia susceptibility gene

BACKGROUND

Schizophrenia is a chronic and severe mental disorder, and it has been predicted to be highly polygenic. Common SNPs located in or near BNIP3L were found to be genome-wide significantly associated with schizophrenia in recent genome-wide association studies. The purpose of our study is to investigate potential causal variants in BNIP3L gene.

RESULTS

We performed targeted sequencing for all exons and un-translated regions of BNIP3L gene among 1806 patients with schizophrenia and 998 healthy controls of Han Chinese origin. Three rare nonsynonymous mutations, BNIP3L (NM_004331): c.52A>G, c.167G>A and c.313A>T, were identified in schizophrenia cases, and two of them were newly reported. The frequencies of these rare nonsynonymous mutations were significantly different between schizophrenia cases and healthy controls. For the common variants, rs147389989 achieved significance in both allelic and genotypic distributions with schizophrenia. Rs1042992 and rs17310286 were significantly associated with schizophrenia in meta-analyses using PGC, CLOZUK, and our new datasets in this study.

CONCLUSIONS

Our findings provided further evidence that BNIP3L gene is a susceptibility gene of schizophrenia and revealed functional and potential causal mutations in BNIP3L. However, more functional validations are suggested to better understand the role of BNIP3L in the etiology of schizophrenia.

Rare and common variants analysis of the EMB gene in patients with schizophrenia

BACKGROUND

Recent genome-wide association study showed rs10940346 locus near EMB gene was significantly associated with schizophrenia and suggested that EMB gene is one of the potentially causal genes for schizophrenia, but no causal variant has been identified. Our study aims to further verify EMB gene is a susceptibility gene for schizophrenia and to identify potentially causal variants in EMB gene that lead to schizophrenia.

METHODS

Targeted sequencing for the un-translated region and all exons of EMB gene was performed among 1803 patients with schizophrenia and 997 healthy controls recruited from Chinese Han population.

RESULTS

A total of 58 high-quality variants were identified in case and control groups. Seven of them are nonsynonymous rare variations, EMB: p.(Ala52Thr), p.(Glu66Gly), p.(Ser93Cys), p.(Ala118Val), p.(Ile131Met), p.(Gly163Arg) and p.(Arg238Tyr), but none of them reached statistical significance. Among them, p.(Ile131Met), p.(Gly163Arg) and p.(Arg238Tyr), were predicted to be deleterious variants. In addition, a common variant, rs3933097 located in 3'-UTR of EMB gene, achieved allelic and genotypic significance with schizophrenia (P_allele = 3.82 × 10^- 6, P_genotype = 3.18 × 10^- 5).

CONCLUSIONS

Our research first presented a comprehensive mutation spectrum of exons and un-translated region in EMB gene for schizophrenia and provided additional evidence of EMB gene being a susceptibility gene for schizophrenia. However, further functional validations are necessary to reveal its role in the etiology of schizophrenia.

Second-Generation Antipsychotics and Dysregulation of Glucose Metabolism: Beyond Weight Gain

Second-generation antipsychotics (SGAs) are the cornerstone of treatment for schizophrenia because of their high clinical efficacy. However, SGA treatment is associated with severe metabolic alterations and body weight gain, which can increase the risk of type 2 diabetes and cardiovascular disease, and greatly accelerate mortality. Several underlying mechanisms have been proposed for antipsychotic-induced weight gain (AIWG), but some studies suggest that metabolic changes in insulin-sensitive tissues can be triggered before the onset of AIWG. In this review, we give an outlook on current research about the metabolic disturbances provoked by SGAs, with a particular focus on whole-body glucose homeostasis disturbances induced independently of AIWG, lipid dysregulation or adipose tissue disturbances. Specifically, we discuss the mechanistic insights gleamed from cellular and preclinical animal studies that have reported on the impact of SGAs on insulin signaling, endogenous glucose production, glucose uptake and insulin secretion in the liver, skeletal muscle and the endocrine pancreas. Finally, we discuss some of the genetic and epigenetic changes that might explain the different susceptibilities of SGA-treated patients to the metabolic side-effects of antipsychotics.

The Role of MIR9-2 in Shared Susceptibility of Psychiatric Disorders during Childhood: A Population-Based Birth Cohort Study

BACKGROUND

It has been suggested that microRNAs (miRNAs; short non-protein-coding RNA molecules that mediate post-transcriptional regulation), including mir-9 and mir-34 families, are important for brain development. Current data suggest that mir-9 and mir-34 may have shared effects across psychiatric disorders. This study aims to explore the role of genetic polymorphisms in the MIR9-2 (rs4916723) and MIR34B/C (rs4938723) genes on the susceptibility of psychiatric disorders in children from the 2004 Pelotas Birth Cohort.

METHODS

Psychiatric disorders were assessed in 3585 individuals using Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV), criteria through the application of standard semi-structured interviews (using the Development and Well-Being Assessment, DAWBA) at the six-years-of-age follow-up. The outcome was defined as the presence of any mental disorder. We also considered two broad groups of internalizing and externalizing disorders to further investigate the role of these variants in mental health.

RESULTS

We observed an association between rs4916723 (MIR9-2) and the presence of any psychiatric disorder (odds ratios (OR) = 0.820; 95% CI = 0.7130-0.944; p = 0.006) and a suggestive effect on internalizing disorders (OR = 0.830; 95% CI = 0.698-0.987; p = 0.035). rs4938723 (MIR34B/C) was not associated with any evaluated outcome.

CONCLUSION

The study suggests that MIR9-2 may have an important role on a broad susceptibility for psychiatric disorders and may be important mainly for internalization problems.

Modulation of Neuro-Dopamine Homeostasis in Juvenile Female Atlantic Cod ( Gadus morhua) Exposed to Polycyclic Aromatic Hydrocarbons and Perfluoroalkyl Substances

The dopaminergic effect of PAH and PFAS mixtures, prepared according to environmentally relevant concentrations, has been studied in juvenile female Atlantic cod ( Gadus morhua). Benzo[a]pyrene, dibenzothiophene, fluorene, naphthalene, phenanthrene, and pyrene were used to prepare a PAH mixture, while PFNA, PFOA, PFOS, and PFTrA were used to prepare a PFAS mixture. Cod were injected intraperitoneally twice, with either a low (1×) or high (20×) dose of each compound mixture or their combinations. After 2 weeks of exposure, levels of plasma 17β-estradiol (E2) were significantly elevated in high PAH/high PFAS treated group. Brain dopamine/metabolite ratios (DOPAC/dopamine and HVA+DOPAC/dopamine) changed with E2 plasma levels, except for high PAH/low PFAS and low PAH/high PFAS treated groups. On the transcript levels, th mRNA inversely correlated with dopamine/metabolite ratios and gnrh2 mRNA levels. Respective decreases and increases of drd1 and drd2a after exposure to the high PAH dose were observed. Specifically, high PFAS exposure decreased both drds, leading to high plasma E2 concentrations. Other studied end points suggest that these compounds, at different doses and combinations, have different toxicity threshold and modes of action. These effects indicate potential alterations in the feedback signaling processes within the dopaminergic pathway by these contaminant mixtures.

hsa-miR-3177-5p and hsa-miR-3178 Inhibit 5-HT1A Expression by Binding the 3'-UTR Region in vitro

Abnormal expression of the 5-HT1A receptor, which is encoded by the HTR1A gene, leads to susceptibilities to neuropsychiatric disorders such as depression, anxiety, and schizophrenia. miRNAs regulate gene expression by recognizing the 3'-UTR region of mRNA. This study evaluated the miRNAs that might identify and subsequently determine the regulatory mechanism of HTR1A gene. Using the HEK-293, U87, SK-N-SH and SH-SY5Y cell lines, we determined the functional sequence of the 3'-UTR region of the HTR1A gene and predicted miRNA binding. Dual luciferase reporter assay and Western Blot were used to confirm the effect of miRNA mimics and inhibitors on endogenous 5-HT1A receptors. In all cell lines, gene expression of the -17 bp to +443 bp fragment containing the complete sequence of the 3'-UTR region was significantly decreased, although mRNA quantification was not different. The +375 bp to +443 bp sequence, which exhibited the most significant change in relative chemiluminescence intensity, was recognized by hsa-miR-3177-5p and hsa-miR-3178. In HEK-293 and U87 cells, hsa-miR-3177-5p significantly inhibited the 5-HT1A receptor expression, while a hsa-miR-3178 inhibitor up-regulated HTR1A gene expression in SK-N-SH and SH-SY5Y cells. By constructing the pmirGLO-vector with the mutated HTR1A gene, we further confirmed that hsa-miR-3177-5p recognized the HTR1A gene tgtacaca at +377 bp to +384 bp, and the +392 bp to +399 bp fragment cgcgccca was identified by hsa-miR-3178. hsa-miR-3177-5p and hsa-miR-3178 had significant inhibitory effects on expression of the HTR1A gene and 5-HT1A receptor and may directly participate in the development of neuropsychiatric diseases.

Rs7219 Regulates the Expression of GRB2 by Affecting miR-1288-Mediated Inhibition and Contributes to the Risk of Schizophrenia in the Chinese Han Population

In the present study, we examined a potential genetic association between the variant rs7219 within the 3'-UTR of GRB2 and the susceptibility to schizophrenia (SCZ) and bipolar disorder (BD) in the Chinese Han population. A genetic association study, including 548 SCZ patients, 512 BD patients, and 598 normal controls, was conducted in the Chinese Han population. Genotyping was performed through the Sequenom MassARRAY technology platform. The expression of GRB2 was detected using quantitative real-time polymerase chain reaction (qRT-PCR). A dual-luciferase reporter assay was performed to determine whether miR-1288 could bind to the 3'-UTR region of GRB2 containing rs7219. We found that rs7219 was significantly associated with the susceptibility to SCZ under different genetic models, including additive [OR (95% CI) = 1.24 (1.02-1.49), P = 0.027], dominant [OR (95% CI) = 1.31 (1.04-1.66), P = 0.025], and allelic models[OR (95% CI) = 1.24 (1.03-1.49), P = 0.027]. However, no significant associations were found between rs7219 and the risk for BD (all P > 0.05). Moreover, we observed that the expression of GRB2 significantly decreased in SCZ patients compared with the controls (P = 0.004). The dual-luciferase reporter assay showed that the minor allele C of rs7219 significantly decreased the luciferase activity by binding miR-1288 (P < 0.001). In summary, we are the first to reveal that rs7219 is significantly associated with the susceptibility to SCZ in the Chinese Han population. Moreover, the minor allele C of rs7219 is identified as a risk allele for SCZ because it generates a binding site for miR-1288, thereby resulting in decreased expression of GRB2 and ultimately increasing the risk of SCZ.

Are FXR Family Proteins Integrators of Dopamine Signaling and Glutamatergic Neurotransmission in Mental Illnesses?

Dopamine receptors and related signaling pathways have long been implicated in pathophysiology and treatment of mental illnesses, including schizophrenia and bipolar disorder. Dopamine signaling may impact neuronal activity by modulation of glutamate neurotransmission. Recent evidence indicates a direct and/or indirect involvement of fragile X-related family proteins (FXR) in the regulation and mediation of dopamine receptor functions. FXRs consists of fragile X mental retardation protein 1 (Fmr1/FMRP) and its autosomal homologs Fxr1 and Fxr2. These RNA-binding proteins are enriched in the brain. Loss of function mutation in human FMR1 is the major genetic contributor to Fragile X mental retardation syndrome. Therefore, the role of FXR proteins has mostly been studied in the context of autism spectrum disorders. However, recent genome-wide association studies have linked this family to schizophrenia, bipolar disorders, and mood regulation pointing toward a broader involvement in mental illnesses. FXR family proteins play an important role in the regulation of glutamate-mediated neuronal activity and plasticity. Here, we discuss the brain-specific functions of FXR family proteins by focusing on the regulation of dopamine receptor functions, ionotropic glutamate receptors-mediated synaptic plasticity and contribution to mental illnesses. Based on recent evidence, we propose that FXR proteins are potential integrators of dopamine signaling and ionotropic glutamate transmission.

Pharmacogenomics in Psychiatric Practice

Pharmacogenomic testing in psychiatry is becoming an established clinical procedure. Several vendors provide clinical interpretation of combinatorial pharmacogenomic testing of gene variants that have documented predictive implications regarding either pharmacologic response or adverse effects in depression and other psychiatric conditions. Such gene profiles have demonstrated improvements in outcome in depression, and reduction of cost of care of patients with inadequate clinical response. Additionally, several new gene variants are being studied to predict specific response in individuals. Many of these genes have demonstrated a role in the pathophysiology of depression or specific depressive symptoms. This article reviews the current state-of-the-art application of psychiatric pharmacogenomics.

Open Chromatin Profiling in hiPSC-Derived Neurons Prioritizes Functional Noncoding Psychiatric Risk Variants and Highlights Neurodevelopmental Loci

Most disease variants lie within noncoding genomic regions, making their functional interpretation challenging. Because chromatin openness strongly influences transcriptional activity, we hypothesized that cell-type-specific open chromatin regions (OCRs) might highlight disease-relevant noncoding sequences. To investigate, we mapped global OCRs in neurons differentiating from hiPSCs, a cellular model for studying neurodevelopmental disorders such as schizophrenia (SZ). We found that the OCRs are highly dynamic and can stratify GWAS-implicated SZ risk variants. Of the more than 3,500 SZ-associated variants analyzed, we prioritized ∼100 putatively functional ones located in neuronal OCRs, including rs1198588, at a leading risk locus flanking MIR137. Excitatory neurons derived from hiPSCs with CRISPR/Cas9-edited rs1198588 or a rare proximally located SZ risk variant showed altered MIR137 expression, dendrite arborization, and synapse maturation. Our study shows that noncoding disease variants in OCRs can affect neurodevelopment, and that analysis of open chromatin regions can help prioritize functionally relevant noncoding variants identified by GWAS.

Molecular Profiling of Human Induced Pluripotent Stem Cell-Derived Hypothalamic Neurones Provides Developmental Insights into Genetic Loci for Body Weight Regulation

Recent data suggest that common genetic risks for metabolic disorders such as obesity may be human-specific and exert effects via the central nervous system. To overcome the limitation of human tissue access for study, we have generated induced human pluripotent stem cell (hiPSC)-derived neuronal cultures that recapture many features of hypothalamic neurones within the arcuate nucleus. In the present study, we have comprehensively characterised this model across development, benchmarked these neurones to in vivo events, and demonstrate a link between obesity risk variants and hypothalamic development. The dynamic transcriptome across neuronal maturation was examined using microarray and RNA sequencing methods at nine time points. K-means clustering of the longitudinal data was conducted to identify co-regulation and microRNA control of biological processes. The transcriptomes were compared with those of 103 samples from 13 brain regions reported in the Genotype-Tissue Expression database (GTEx) using principal components analysis. Genes with proximity to body mass index (BMI)-associated genetic variants were mapped to the developmentally expressed genesets, and enrichment significance was assessed with Fisher's exact test. The human neuronal cultures have a transcriptional and physiological profile of neuropeptide Y/agouti-related peptide arcuate nucleus neurones. The neuronal transcriptomes were highly correlated with adult hypothalamus compared to any other brain region from the GTEx. Also, approximately 25% of the transcripts showed substantial changes in expression across neuronal development and potential co-regulation of biological processes that mirror neuronal development in vivo. These developmentally expressed genes were significantly enriched for genes in proximity to BMI-associated variants. We confirmed the utility of this in vitro human model for studying the development of key hypothalamic neurones involved in energy balance and show that genes at loci associated with body weight regulation may share a pattern of developmental regulation. These data support the need to investigate early development to elucidate the human-specific central nervous system pathophysiology underlying obesity susceptibility.

Genetic variation in the 3'-untranslated region of PAK1 influences schizophrenia susceptibility

The present study aimed to investigate the association of two polymorphisms (rs2844337 and rs11237200) in the P21 protein (cell division control protein 42/Rac)-activated kinase 1 gene with susceptibility to schizophrenia (SCZ) in Chinese Zhuang and Chinese Han populations. A total of 700 patients with SCZ and 700 healthy controls were recruited. Rs2844337 and rs11237200 polymorphisms were genotyped using Sequenom technology. A total of 591 patients completed the Positive and Negative Syndrome Scale (PANSS) assessment. Data were statistically analyzed using PLINK version 1.07 and SPSS version 17.0. In the Chinese Han population, the genotypic (P=0.038) and allelic (P=0.033) frequencies of the 3'-untranslated region (UTR) genetic variation of rs2844337 in patients were significantly decreased compared to that in controls; these frequencies were significantly associated with SCZ susceptibility in the additive model (P_adj=0.032) and in the recessive model (P_adj=0.031). Moreover, the TG haplotype constructed by rs2844337 and rs11237200 polymorphisms remained significantly associated with SCZ risk following adjustment for gender and age and applying a Bonferroni correction in the Chinese Han population (P_adj=0.003, P_BC=0.009). The adjacent 5'-UTR genetic variation of rs11237200 was significantly associated with the total score (P_adj=0.006), positive scale score (P_adj=0.014) and general psychopathology scale scores (P_adj=0.009) in the recessive model of the Chinese Han population. However, these polymorphisms were not significantly associated with SCZ susceptibility or the PANSS scores in the Chinese Zhuang population. In conclusion, variations in the PAK1 gene influenced the susceptibility and severity of the clinical symptoms of SCZ in the Chinese Han population investigated in the present study.

MicroRNAs in Neurocognitive Dysfunctions: New Molecular Targets for Pharmacological Treatments?

BACKGROUND

Neurodegenerative and cognitive disorders are multifactorial diseases (i.e., involving neurodevelopmental, genetic, age or environmental factors) characterized by an abnormal development that affects neuronal function and integrity. Recently, an increasing number of studies revealed that the dysregulation of microRNAs (miRNAs) may be involved in the etiology of cognitive disorders as Alzheimer, Parkinson, and Huntington's diseases, Schizophrenia and Autism spectrum disorders.

METHODS

From an extensive search in bibliographic databases of peer-reviewed research literature, we identified relevant published studies related to specific key words such as memory, cognition, neurodegenerative disorders, neurogenesis and miRNA. We then analysed, evaluated and summerized scientific evidences derived from these studies.

RESULTS

We first briefly summarize the basic molecular events involved in memory, a process inherent to cognitive disease, and then describe the role of miRNAs in neurodevelopment, synaptic plasticity and memory. Secondly, we provide an overview of the impact of miRNA dysregulation in the pathogenesis of different neurocognitive disorders, and lastly discuss the feasibility of miRNA-based therapeutics in the treatment of these disorders.

CONCLUSION

This review highlights the molecular basis of neurodegenerative and cognitive disorders by focusing on the impact of miRNAs dysregulation in these pathological phenotypes. Altogether, the published reports suggest that miRNAs-based therapy could be a viable therapeutic alternative to current treatment options in the future.

Genetic variation in the miR-708 gene and its binding targets in bipolar disorder

OBJECTIVE

rs12576775 was found to be associated with bipolar disorder (BD) in a genome-wide association study (GWAS). The GWAS signal implicates genes for the microRNAs miR-708 and miR-5579 and the first exon of the Odd Oz/ten-m homolog 4 gene (ODZ4). In the present study, miR-708, its surrounding region, and its targets were analyzed for potential BD-associated functional variants.

METHODS

The miR-708 gene and surrounding regions were screened for variation using high-resolution melting (HRM) analysis in 1099 cases of BD, followed by genotyping of rare variants in an enlarged sample of 2078 subjects with BD, 1303 subjects with schizophrenia, and 1355 healthy controls. Whole-genome sequencing data from 99 subjects with BD were analyzed for variation in potential miR-708 binding sites. The minor allele frequencies (MAFs) of these variants were compared with those reported in reference individuals.

RESULTS

Three variants detected by HRM were selected to be genotyped. rs754333774 was detected in three cases of BD, two cases of schizophrenia, and no controls. This variant is located 260 base pairs upstream from miR-708 and may play a role in controlling the expression of the miR. Four variants were identified in miR-708 targets binding sites. The MAFs of each of these variants were similar in BD and reference samples.

CONCLUSIONS

We report a single recurrent variant located near the miR-708 gene that may have a role in BD and schizophrenia susceptibility. These findings await replication in independent cohorts, as do functional analyses of the potential consequences of this variant.

Noncoding RNA Regulation of Dopamine Signaling in Diseases of the Central Nervous System

Dopaminergic neurotransmission mediates a majority of the vital central nervous system functions. Disruption of these synaptic events provokes a multitude of neurological pathologies, including Parkinson's, schizophrenia, depression, and addiction. Growing evidence supports a key role for noncoding RNA (ncRNA) regulation in the synapse. This review will discuss the role of both short and long ncRNAs in dopamine signaling, including bioinformatic examination of the pathways they target. Specifically, we focus on the contribution of ncRNAs to dopaminergic dysfunction in neurodegenerative as well as psychiatric disease.

Analyzing the Role of MicroRNAs in Schizophrenia in the Context of Common Genetic Risk Variants

IMPORTANCE

The recent implication of 108 genomic loci in schizophrenia marked a great advancement in our understanding of the disease. Against the background of its polygenic nature there is a necessity to identify how schizophrenia risk genes interplay. As regulators of gene expression, microRNAs (miRNAs) have repeatedly been implicated in schizophrenia etiology. It is therefore of interest to establish their role in the regulation of schizophrenia risk genes in disease-relevant biological processes.

OBJECTIVE

To examine the role of miRNAs in schizophrenia in the context of disease-associated genetic variation.

DESIGN, SETTING, AND PARTICIPANTS

The basis of this study was summary statistics from the largest schizophrenia genome-wide association study meta-analysis to date (83 550 individuals in a meta-analysis of 52 genome-wide association studies) completed in 2014 along with publicly available data for predicted miRNA targets. We examined whether schizophrenia risk genes were more likely to be regulated by miRNA. Further, we used gene set analyses to identify miRNAs that are regulators of schizophrenia risk genes.

MAIN OUTCOMES AND MEASURES

Results from association tests for miRNA targetomes and related analyses.

RESULTS

In line with previous studies, we found that similar to other complex traits, schizophrenia risk genes were more likely to be regulated by miRNAs (P < 2 × 10-16). Further, the gene set analyses revealed several miRNAs regulating schizophrenia risk genes, with the strongest enrichment for targets of miR-9-5p (P = .0056 for enrichment among the top 1% most-associated single-nucleotide polymorphisms, corrected for multiple testing). It is further of note that MIR9-2 is located in a genomic region showing strong evidence for association with schizophrenia (P = 7.1 × 10-8). The second and third strongest gene set signals were seen for the targets of miR-485-5p and miR-137, respectively.

CONCLUSIONS AND RELEVANCE

This study provides evidence for a role of miR-9-5p in the etiology of schizophrenia. Its implication is of particular interest as the functions of this neurodevelopmental miRNA tie in with established disease biology: it has a regulatory loop with the fragile X mental retardation homologue FXR1 and regulates dopamine D2 receptor density.

Altering the course of schizophrenia: progress and perspectives

Despite a lack of recent progress in the treatment of schizophrenia, our understanding of its genetic and environmental causes has considerably improved, and their relationship to aberrant patterns of neurodevelopment has become clearer. This raises the possibility that 'disease-modifying' strategies could alter the course to - and of - this debilitating disorder, rather than simply alleviating symptoms. A promising window for course-altering intervention is around the time of the first episode of psychosis, especially in young people at risk of transition to schizophrenia. Indeed, studies performed in both individuals at risk of developing schizophrenia and rodent models for schizophrenia suggest that pre-diagnostic pharmacotherapy and psychosocial or cognitive-behavioural interventions can delay or moderate the emergence of psychosis. Of particular interest are 'hybrid' strategies that both relieve presenting symptoms and reduce the risk of transition to schizophrenia or another psychiatric disorder. This Review aims to provide a broad-based consideration of the challenges and opportunities inherent in efforts to alter the course of schizophrenia.

Potential involvement of the interleukin-18 pathway in schizophrenia

OBJECTIVE

Accumulating evidence implicates inflammatory cytokines in the development of psychiatric disorders, including schizophrenia (SZ). IL-18 is one of cytokines that plays a crucial role in immune response and neurodevelopment. We aimed to investigate potential genetic alterations of the cytokine system underpinning SZ.

METHODS

We tested the association of genetic variants within the cytokine-cytokine receptor interaction (CCRI) pathway with SZ, using GWAS-derived data involving 768 adult SZ patients and 1348 controls, and replicated the association of IL18R1 rs1035130 with SZ in an independent sample of 1957 adult patients and 1509 controls. We compared expression levels of IL18, IL18R1 and IL18RAP in peripheral blood of a cohort of adolescent participants (<18 years), including 14 early-onset SZ patients and 13 healthy controls. Furthermore, we carried out a cis-eQTL (expression Quantitative Trait Loci) and a cis-mQTL (Methylation Quantitative Trait Loci) analysis for IL18R1 rs1035130.

RESULTS

In the discovery stage, we detected association signals within two IL18 pathway genes, IL18R1 and IL18RAP, with the most significant marker being IL18R1 rs1035130 (P = 1.84E-7, OR = 0.70). In the validation stage, we found rs1035130 was associated with SZ (P = 0.028, OR = 0.89). Expressions of IL18 and IL18R1 were altered in blood of SZ patients compared with 13 controls. Furthermore, cis-QTL analyses indicated that rs1035130 was associated with an eQTL and 5 mQTLs.

CONCLUSION

Our findings suggest the alteration of IL18 pathway may contribute to the psychopathology of SZ.

PINK1 Deficiency Decreases Expression Levels of mir-326, mir-330, and mir-3099 during Brain Development and Neural Stem Cell Differentiation

PTEN-induced putative kinase 1 (PINK1) is a Parkinson's disease (PD) gene. We examined miRNAs regulated by PINK1 during brain development and neural stem cell (NSC) differentiation, and found that lvels of miRNAs related to tumors and inflammation were different between 1-day-old-wild type (WT) and PINK1-knockout (KO) mouse brains. Notably, levels of miR-326, miR-330 and miR-3099, which are related to astroglioma, increased during brain development and NSC differentiation, and were significantly reduced in the absence of PINK1. Interestingly, in the presence of ciliary neurotrophic factor (CNTF), which pushes differentiation of NSCs into astrocytes, miR-326, miR-330, and miR-3099 levels in KO NSCs were also lower than those in WT NSCs. Furthermore, mimics of all three miRNAs increased expression of the astrocytic marker glial fibrillary acidic protein (GFAP) during differentiation of KO NSCs, but inhibitors of these miRNAs decreased GFAP expression in WT NSCs. Moreover, these miRNAs increased the translational efficacy of GFAP through the 3'-UTR of GFAP mRNA. Taken together, these results suggest that PINK1 deficiency reduce expression levels of miR-326, miR-330 and miR-3099, which may regulate GFAP expression during NSC differentiation and brain development.

A Dishful of a Troubled Mind: Induced Pluripotent Stem Cells in Psychiatric Research

Neuronal differentiation of induced pluripotent stem cells and direct reprogramming represent powerful methods for modeling the development of neurons in vitro. Moreover, this approach is also a means for comparing various cellular phenotypes between cell lines originating from healthy and diseased individuals or isogenic cell lines engineered to differ at only one or a few genomic loci. Despite methodological constraints and initial skepticism regarding this approach, the field is expanding at a fast pace. The improvements include the development of new differentiation protocols resulting in selected neuronal populations (e.g., dopaminergic, GABAergic, hippocampal, and cortical), the widespread use of genome editing methods, and single-cell techniques. A major challenge awaiting in vitro disease modeling is the integration of clinical data in the models, by selection of well characterized clinical populations. Ideally, these models will also demonstrate how different diagnostic categories share overlapping molecular disease mechanisms, but also have unique characteristics. In this review we evaluate studies with regard to the described developments, to demonstrate how differentiation of induced pluripotent stem cells and direct reprogramming can contribute to psychiatry.

Impact of recent innovations in the use of mass cytometry in support of drug development

Cytometry by time-of-flight (CyTOF) is a novel technology for the real-time analysis of single cells. CyTOF is a significant advance in fields including immunology, hematology, and oncology. It resolves multiple metal-conjugated probes per cell with minimal signal overlap, which maximizes the information obtained from each individual sample. CyTOF provides the ability to phenotypically and functionally profile cells from normal and diseased states. Single cell technologies enable researchers to measure the effects of a drug at the single cell level and better understand its mechanism of action. Here, we discuss novel instruments for the analysis of individual biological cells, the impact of recent innovations in support of drug development, and the important roles of CyTOF in drug profiling.

Transcriptome outlier analysis implicates schizophrenia susceptibility genes and enriches putatively functional rare genetic variants

We searched a gene expression dataset comprised of 634 schizophrenia (SZ) cases and 713 controls for expression outliers (i.e., extreme tails of the distribution of transcript expression values) with SZ cases overrepresented compared with controls. These outlier genes were enriched for brain expression and for genes known to be associated with neurodevelopmental disorders. SZ cases showed higher outlier burden (i.e., total outlier events per subject) than controls for genes within copy number variants (CNVs) associated with SZ or neurodevelopmental disorders. Outlier genes were enriched for CNVs and for rare putative regulatory variants, but this only explained a small proportion of the outlier subjects, highlighting the underlying presence of additional genetic and potentially, epigenetic mechanisms.

Polymorphisms Falling Within Putative miRNA Target Sites in the 3'UTR Region of SIRT2 and DRD2 Genes Are Correlated With Human Longevity

Many studies have suggested that individual differences in aging phenotypes may be associated to polymorphisms affecting gene regulation. As single-nucleotide polymorphisms (SNPs) in the 3'-untranslated regions (3'UTR) targeted by microRNAs (miRNAs) can alter the strength of miRNA binding (and, consequently, the regulation of target genes), we wondered whether these SNPs (known as miRSNPs) affect the individual chance to become long-lived. Thus, we estimated the effect of miRSNPs falling in the 3'-untranslated regions of 140 aging-related genes on the DNA/miRNA bond. The 24 miRSNPs with the highest difference of binding energy between the two alleles were then investigated for their association with longevity by case-control analysis. Two SNPs,SIRT2-rs45592833 G/T and DRD2-rs6276 A/G, provided a significant association with human longevity, also after correcting for multiple comparisons. For both SNPs, the minor allele was associated with a significantly decreased chance to became long-lived in an allele dose-dependent manner (p= 1.090 × 10(-6)and 1.964 × 10(-4)forSIRT2 and DRD2, respectively). The results indicate that the individual aging phenotype may be affected by the variability of specific miRNA targeted regions, as shown for SIRT2 and DRD2, and may suggest further studies to analyze the variability of gene expression regulation as a modulator of aging phenotypes.

Path from schizophrenia genomics to biology: gene regulation and perturbation in neurons derived from induced pluripotent stem cells and genome editing

Schizophrenia (SZ) is a devastating mental disorder afflicting 1% of the population. Recent genome-wide association studies (GWASs) of SZ have identified >100 risk loci. However, the causal variants/genes and the causal mechanisms remain largely unknown, which hinders the translation of GWAS findings into disease biology and drug targets. Most risk variants are noncoding, thus likely regulate gene expression. A major mechanism of transcriptional regulation is chromatin remodeling, and open chromatin is a versatile predictor of regulatory sequences. MicroRNA-mediated post-transcriptional regulation plays an important role in SZ pathogenesis. Neurons differentiated from patient-specific induced pluripotent stem cells (iPSCs) provide an experimental model to characterize the genetic perturbation of regulatory variants that are often specific to cell type and/or developmental stage. The emerging genome-editing technology enables the creation of isogenic iPSCs and neurons to efficiently characterize the effects of SZ-associated regulatory variants on SZ-relevant molecular and cellular phenotypes involving dopaminergic, glutamatergic, and GABAergic neurotransmissions. SZ GWAS findings equipped with the emerging functional genomics approaches provide an unprecedented opportunity for understanding new disease biology and identifying novel drug targets.

A rare functional noncoding variant at the GWAS-implicated MIR137/MIR2682 locus might confer risk to schizophrenia and bipolar disorder

Schizophrenia (SZ) genome-wide association studies (GWASs) have identified common risk variants in >100 susceptibility loci; however, the contribution of rare variants at these loci remains largely unexplored. One of the strongly associated loci spans MIR137 (miR137) and MIR2682 (miR2682), two microRNA genes important for neuronal function. We sequenced ∼6.9 kb MIR137/MIR2682 and upstream regulatory sequences in 2,610 SZ cases and 2,611 controls of European ancestry. We identified 133 rare variants with minor allele frequency (MAF) <0.5%. The rare variant burden in promoters and enhancers, but not insulators, was associated with SZ (p = 0.021 for MAF < 0.5%, p = 0.003 for MAF < 0.1%). A rare enhancer SNP, 1:g.98515539A>T, presented exclusively in 11 SZ cases (nominal p = 4.8 × 10(-4)). We further identified its risk allele T in 2 of 2,434 additional SZ cases, 11 of 4,339 bipolar (BP) cases, and 3 of 3,572 SZ/BP study controls and 1,688 population controls; yielding combined p values of 0.0007, 0.0013, and 0.0001 for SZ, BP, and SZ/BP, respectively. The risk allele T of 1:g.98515539A>T reduced enhancer activity of its flanking sequence by >50% in human neuroblastoma cells, predicting lower expression of MIR137/MIR2682. Both empirical and computational analyses showed weaker transcription factor (YY1) binding by the risk allele. Chromatin conformation capture (3C) assay further indicated that 1:g.98515539A>T influenced MIR137/MIR2682, but not the nearby DPYD or LOC729987. Our results suggest that rare noncoding risk variants are associated with SZ and BP at MIR137/MIR2682 locus, with risk alleles decreasing MIR137/MIR2682 expression.

Heterogeneity and individuality: microRNAs in mental disorders

MicroRNAs are about 22 nucleotide long single-stranded RNA molecules, negatively regulating gene expression of a single gene or a gene network. In neural tissues, they have been implicated in developmental and neuroplasticity-related processes, such as neurogenesis, differentiation, apoptosis and long-term potentiation. Their molecular mode of action is reminiscent of findings of genome-wide association studies in mental disorders, unable to attribute the risk of disease to a specific gene, but rather to multiple genes, gene-networks and gene-environment interaction. As such, microRNAs are an attractive target for research. Here, we review clinical studies conducted in humans on microRNAs in mental disorders with a particular focus on schizophrenia, bipolar disorder, major depressive disorder and anxiety disorders. The majority of clinical studies have focused on schizophrenia. The most robust finding has been reported for rs1625579 located in MIR137HG, which was associated with schizophrenia on a genome-wide level. Concerning bipolar disorder, major depression and anxiety disorders, promising results have been published, but only a considerably smaller number of clinical studies is available and genome-wide association studies did not suggest a direct link to microRNAs so far. Expression of microRNAs as biomarkers of mental disorders and treatment response is currently emerging with preliminary results. Larger-scaled genetic and functional studies along with translational research are needed to enhance our understanding of microRNAs in mental disorders. These studies will aid in disentangling the complex genetic nature of these disorders and possibly contribute to the development of novel, individualized diagnostic and therapeutic approaches.

MicroRNAs: Small molecules with big roles in neurodevelopment and diseases

MicroRNAs (miRNAs) are single-stranded, non-coding RNA molecules that play important roles in the development and functions of the brain. Extensive studies have revealed critical roles for miRNAs in brain development and function. Dysregulation or altered expression of miRNAs is associated with abnormal brain development and pathogenesis of neurodevelopmental diseases. This review serves to highlight the versatile roles of these small RNA molecules in normal brain development and their association with neurodevelopmental disorders, in particular, two closely related neuropsychiatric disorders of neurodevelopmental origin, schizophrenia and bipolar disorder.