Feasibility and relevance of examining lymphoblastoid cell lines to study role of microRNAs in autism

A Comparative Review of microRNA Expression Patterns in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by a wide spectrum of deficits in social interaction, communication, and behavior. There is a significant genetic component to ASD, yet no single gene variant accounts for >1% of incidence. Posttranscriptional mechanisms such as microRNAs (miRNAs) regulate gene expression without altering the genetic code. They are abundant in the developing brain and are dysregulated in children with ASD. Patterns of miRNA expression are altered in the brain, blood, saliva, and olfactory precursor cells of ASD subjects. The ability of miRNAs to regulate broad molecular pathways in response to environmental stimuli makes them an intriguing player in ASD, a disorder characterized by genetic predisposition with ill-defined environmental triggers. In addition, the availability and extracellular stability of miRNAs make them an ideal candidate for biomarker discovery. Here, we discuss 27 miRNAs with overlap across ASD studies, including 3 miRNAs identified in 3 or more studies (miR-23a, miR-146a, and miR-106b). Together, these 27 miRNAs have 1245 high-confidence mRNA targets, a significant number of which are expressed in the brain. Furthermore, these mRNA targets demonstrate over-representation of autism-related genes with enrichment of neurotrophic signaling molecules. Brain-derived neurotrophic factor, a molecule involved in hippocampal neurogenesis and altered in ASD, is targeted by 6 of the 27 miRNAs of interest. This neurotrophic pathway represents one intriguing mechanism by which perturbations in miRNA signaling might influence central nervous system development in children with ASD.

The Role of MicroRNAs in Cerebellar Development and Autism Spectrum Disorder During Embryogenesis

MicroRNAs (miRNAs) are a class of small non-coding RNA molecules with wide-ranging and subtle effects on protein production. Their activity during the development of the cerebellum provides a valuable exemplar of how non-coding molecules may assist the development and function of the central nervous system and drive neurodevelopmental disorders. Three distinct aspects of miRNA contribution to early cerebellar development will here be reviewed. Aspects are the establishment of the cerebellar anlage, the generation and maturation of at least two principal cell types of the developing cerebellar microcircuit, and the etiology and early progression of autism spectrum disorder. It will be argued here that the autism spectrum is an adept model to explore miRNA impact on the cognitive and affective processes that descend from the developing cerebellum.

Fluoxetine Increases the Expression of miR-572 and miR-663a in Human Neuroblastoma Cell Lines

Evidence suggests neuroprotective effects of fluoxetine, a selective serotonin reuptake inhibitor (SSRI), on the developed neurons in the adult brain. In contrast, the drug may be deleterious to immature or undifferentiated neural cells, although the mechanism is unclear. Recent investigations have suggested that microRNAs (miRNA) may be critical for effectiveness of psychotropic drugs including SSRI. We investigated whether fluoxetine could modulate expressions of neurologically relevant miRNAs in two neuroblastoma SK-N-SH and SH-SY5Y cell lines. Initial screening results revealed that three (miR-489, miR-572 and miR-663a) and four (miR-320a, miR-489, miR-572 and miR-663a) miRNAs were up-regulated in SK-N-SH cells and SH-SY5Y cells, respectively, after 24 hours treatment of fluoxetine (1–25 μM). Cell viability was reduced according to the dose of fluoxetine. The upregulation of miR-572 and miR-663a was consistent in both the SH-SY5Y and SK-N-SH cells, confirmed by a larger scale culture condition. Our data is the first in vitro evidence that fluoxetine could increase the expression of miRNAs in undifferentiated neural cells, and that putative target genes of those miRNAs have been shown to be involved in fundamental neurodevelopmental processes.

Phenotyping, Etiological Factors, and Biomarkers: Toward Precision Medicine in Autism Spectrum Disorders

Despite the progress made in understanding the biology of autism spectrum disorder (ASD), effective biological interventions for the core symptoms remain elusive. Because of the etiological heterogeneity of ASD, identification of a "one-size-fits-all" treatment approach will likely continue to be challenging. A meeting was convened at the University of Missouri and the Thompson Center to discuss strategies for stratifying patients with ASD for the purpose of moving toward precision medicine. The "white paper" presented here articulates the challenges involved and provides suggestions for future solutions.

MicroRNAs: Key Regulators in the Central Nervous System and Their Implication in Neurological Diseases

MicroRNAs (miRNAs) are a class of small, well-conserved noncoding RNAs that regulate gene expression post-transcriptionally. They have been demonstrated to regulate a lot of biological pathways and cellular functions. Many miRNAs are dynamically regulated during central nervous system (CNS) development and are spatially expressed in adult brain indicating their essential roles in neural development and function. In addition, accumulating evidence strongly suggests that dysfunction of miRNAs contributes to neurological diseases. These observations, together with their gene regulation property, implicated miRNAs to be the key regulators in the complex genetic network of the CNS. In this review, we first focus on the ways through which miRNAs exert the regulatory function and how miRNAs are regulated in the CNS. We then summarize recent findings that highlight the versatile roles of miRNAs in normal CNS physiology and their association with several types of neurological diseases. Subsequently we discuss the limitations of miRNAs research based on current studies as well as the potential therapeutic applications and challenges of miRNAs in neurological disorders. We endeavor to provide an updated description of the regulatory roles of miRNAs in normal CNS functions and pathogenesis of neurological diseases.

Salivary miRNA profiles identify children with autism spectrum disorder, correlate with adaptive behavior, and implicate ASD candidate genes involved in neurodevelopment

Background

Autism spectrum disorder (ASD) is a common neurodevelopmental disorder that lacks adequate screening tools, often delaying diagnosis and therapeutic interventions. Despite a substantial genetic component, no single gene variant accounts for >1 % of ASD incidence. Epigenetic mechanisms that include microRNAs (miRNAs) may contribute to the ASD phenotype by altering networks of neurodevelopmental genes. The extracellular availability of miRNAs allows for painless, noninvasive collection from biofluids. In this study, we investigated the potential for saliva-based miRNAs to serve as diagnostic screening tools and evaluated their potential functional importance.

Methods

Salivary miRNA was purified from 24 ASD subjects and 21 age- and gender-matched control subjects. The ASD group included individuals with mild ASD (DSM-5 criteria and Autism Diagnostic Observation Schedule) and no history of neurologic disorder, pre-term birth, or known chromosomal abnormality. All subjects completed a thorough neurodevelopmental assessment with the Vineland Adaptive Behavior Scales at the time of saliva collection. A total of 246 miRNAs were detected and quantified in at least half the samples by RNA-Seq and used to perform between-group comparisons with non-parametric testing, multivariate logistic regression and classification analyses, as well as Monte-Carlo Cross-Validation (MCCV). The top miRNAs were examined for correlations with measures of adaptive behavior. Functional enrichment analysis of the highest confidence mRNA targets of the top differentially expressed miRNAs was performed using the Database for Annotation, Visualization, and Integrated Discovery (DAVID), as well as the Simons Foundation Autism Database (AutDB) of ASD candidate genes.

Results

Fourteen miRNAs were differentially expressed in ASD subjects compared to controls (p <0.05; FDR <0.15) and showed more than 95 % accuracy at distinguishing subject groups in the best-fit logistic regression model. MCCV revealed an average ROC-AUC value of 0.92 across 100 simulations, further supporting the robustness of the findings. Most of the 14 miRNAs showed significant correlations with Vineland neurodevelopmental scores. Functional enrichment analysis detected significant over-representation of target gene clusters related to transcriptional activation, neuronal development, and AutDB genes.

Conclusion

Measurement of salivary miRNA in this pilot study of subjects with mild ASD demonstrated differential expression of 14 miRNAs that are expressed in the developing brain, impact mRNAs related to brain development, and correlate with neurodevelopmental measures of adaptive behavior. These miRNAs have high specificity and cross-validated utility as a potential screening tool for ASD.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-016-0586-x) contains supplementary material, which is available to authorized users.

Circulating microRNAs as a Novel Class of Potential Diagnostic Biomarkers in Neuropsychiatric Disorders

Neuropsychiatric diseases, such as schizophrenia, bipolar disorder (BD), major depressive disorder (MDD) and autism spectrum disorder (ASD), are a huge burden on society, impairing the health of those affected, as well as their ability to learn and work. Biomarkers that reflect the dysregulations linked to neuropsychiatric diseases may potentially assist the diagnosis of these disorders. Most of these biomarkers are found in the brain tissue, which is not easily accessible. This is the challenge for the search of novel biomarkers that are present in various body fluids, including serum or plasma. As a group of important endogenous small noncoding RNAs that regulate gene expression at post-transcriptional level, microRNAs (miRNAs) play a crucial role in many physiological and pathological processes. Previously, researchers discovered that miRNAs contribute to the neurodevelopment and maturation, including neurite outgrowth, dendritogenesis and dendritic spine formation. These developments underline the significance of miRNAs as potential biomarkers for diagnosing and prognosing central nervous system diseases. Accumulated evidence indicates that there are considerable differences between the cell-free miRNA expression profiles of healthy subjects and those of patients. Therefore, circulating miRNAs are likely to become a new class of noninvasive, sensitive biomarkers. Despite the fact that little is known about the origin and functions of circulating miRNAs, their essential roles in the clinical diagnosis and prognosis of neuropsychiatric diseases make them attractive biomarkers. In this review we cover the increasing amounts of dataset that have accumulated in the last years on the use of circulating miRNAs and their values as potential biomarkers in most areas of neuropsychiatric diseases.

E Proteins and ID Proteins: Helix-Loop-Helix Partners in Development and Disease

The basic Helix-Loop-Helix (bHLH) proteins represent a well-known class of transcriptional regulators. Many bHLH proteins act as heterodimers with members of a class of ubiquitous partners, the E proteins. A widely expressed class of inhibitory heterodimer partners-the Inhibitor of DNA-binding (ID) proteins-also exists. Genetic and molecular analyses in humans and in knockout mice implicate E proteins and ID proteins in a wide variety of diseases, belying the notion that they are non-specific partner proteins. Here, we explore relationships of E proteins and ID proteins to a variety of disease processes and highlight gaps in knowledge of disease mechanisms.

The balancing act of GABAergic synapse organizers

GABA (γ-aminobutyric acid) is the main neurotransmitter at inhibitory synapses in the mammalian brain. It is essential for maintaining the excitation and inhibition (E/I) ratio, whose imbalance underlies various brain diseases. Emerging information about inhibitory synapse organizers provides a novel molecular framework for understanding E/I balance at the synapse, circuit, and systems levels. This review highlights recent advances in deciphering these components of the inhibitory synapse and their roles in the development, transmission, and circuit properties of inhibitory synapses. We also discuss how their dysfunction may lead to a variety of brain disorders, suggesting new therapeutic strategies based on balancing the E/I ratio.

Profiling olfactory stem cells from living patients identifies miRNAs relevant for autism pathophysiology

Background

Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders caused by the interaction between genetic vulnerability and environmental factors. MicroRNAs (miRNAs) are key posttranscriptional regulators involved in multiple aspects of brain development and function. Previous studies have investigated miRNAs expression in ASD using non-neural cells like lymphoblastoid cell lines (LCL) or postmortem tissues. However, the relevance of LCLs is questionable in the context of a neurodevelopmental disorder, and the impact of the cause of death and/or post-death handling of tissue likely contributes to the variations observed between studies on brain samples.

Methods

miRNA profiling using TLDA high-throughput real-time qPCR was performed on miRNAs extracted from olfactory mucosal stem cells (OMSCs) biopsied from eight patients and six controls. This tissue is considered as a closer tissue to neural stem cells that could be sampled in living patients and was never investigated for such a purpose before. Real-time PCR was used to validate a set of differentially expressed miRNAs, and bioinformatics analysis determined common pathways and gene targets. Luciferase assays and real-time PCR analysis were used to evaluate the effect of miRNAs misregulation on the expression and translation of several autism-related transcripts. Viral vector-mediated expression was used to evaluate the impact of miRNAs deregulation on neuronal or glial cells functions.

Results

We identified a signature of four miRNAs (miR-146a, miR-221, miR-654-5p, and miR-656) commonly deregulated in ASD. This signature is conserved in primary skin fibroblasts and may allow discriminating between ASD and intellectual disability samples. Putative target genes of the differentially expressed miRNAs were enriched for pathways previously associated to ASD, and altered levels of neuronal transcripts targeted by miR-146a, miR-221, and miR-656 were observed in patients’ cells. In the mouse brain, miR-146a, and miR-221 display strong neuronal expression in regions important for high cognitive functions, and we demonstrated that reproducing abnormal miR-146a expression in mouse primary cell cultures leads to impaired neuronal dendritic arborization and increased astrocyte glutamate uptake capacities.

Conclusions

While independent replication experiments are needed to clarify whether these four miRNAS could serve as early biomarkers of ASD, these findings may have important diagnostic implications. They also provide mechanistic connection between miRNA dysregulation and ASD pathophysiology and may open up new opportunities for therapeutic.

Electronic supplementary material

The online version of this article (doi:10.1186/s13229-015-0064-6) contains supplementary material, which is available to authorized users.

Autism Spectrum Disorder - A Complex Genetic Disorder

Autism spectrum disorder is an entity that reflects a scientific consensus that several previously separated disorders are actually a single spectrum disorder with different levels of symptom severity in two core domains - deficits in social communication and interaction, and restricted repetitive behaviors. Autism spectrum disorder is diagnosed in all racial, ethnic and socioeconomic groups and because of its increased prevalence, reported worldwide through the last years, made it one of the most discussed child psychiatric disorders. In term of aetiology as several other complex diseases, Autism spectrum disorder is considered to have a strong genetic component.

Specific Regional and Age-Related Small Noncoding RNA Expression Patterns Within Superior Temporal Gyrus of Typical Human Brains Are Less Distinct in Autism Brains

Small noncoding RNAs play a critical role in regulating messenger RNA throughout brain development and when altered could have profound effects leading to disorders such as autism spectrum disorders (ASD). We assessed small noncoding RNAs, including microRNA and small nucleolar RNA, in superior temporal sulcus association cortex and primary auditory cortex in typical and ASD brains from early childhood to adulthood. Typical small noncoding RNA expression profiles were less distinct in ASD, both between regions and changes with age. Typical micro-RNA coexpression associations were absent in ASD brains. miR-132, miR-103, and miR-320 micro-RNAs were dysregulated in ASD and have previously been associated with autism spectrum disorders. These diminished region- and age-related micro-RNA expression profiles are in line with previously reported findings of attenuated messenger RNA and long noncoding RNA in ASD brain. This study demonstrates alterations in superior temporal sulcus in ASD, a region implicated in social impairment, and is the first to demonstrate molecular alterations in the primary auditory cortex.

Functional genomics of human brain development and implications for autism spectrum disorders

Transcription of the inherited DNA sequence into copies of messenger RNA is the most fundamental process by which the genome functions to guide development. Encoded sequence information, inherited epigenetic marks and environmental influences all converge at the level of mRNA gene expression to allow for cell-type-specific, tissue-specific, spatial and temporal patterns of expression. Thus, the transcriptome represents a complex interplay between inherited genomic structure, dynamic experiential demands and external signals. This property makes transcriptome studies uniquely positioned to provide insight into complex genetic-epigenetic-environmental processes such as human brain development, and disorders with non-Mendelian genetic etiologies such as autism spectrum disorders. In this review, we describe recent studies exploring the unique functional genomics profile of the human brain during neurodevelopment. We then highlight two emerging areas of research with great potential to increase our understanding of functional neurogenomics-non-coding RNA expression and gene interaction networks. Finally, we review previous functional genomics studies of autism spectrum disorder in this context, and discuss how investigations at the level of functional genomics are beginning to identify convergent molecular mechanisms underlying this genetically heterogeneous disorder.

Common and rare variants of microRNA genes in autism spectrum disorders

OBJECTIVES

MicroRNAs (miRNAs) are post-transcriptional regulators that have been shown to be involved in disease susceptibility. Here we explore the possible contribution of common and rare variants in miRNA genes in autism spectrum disorders (ASD).

METHODS

A total of 350 tag SNPs from 163 miRNA genes were genotyped in 636 ASD cases and 673 controls. A replication study was performed in a sample of 449 ASD cases and 415 controls. Additionally, rare variants in 701 miRNA genes of 41 ASD patients were examined using whole-exome sequencing.

RESULTS

The most significant association in the discovery sample was obtained for the miR-133b/miR-206 cluster (rs16882131, P = 0.00037). The replication study did not reach significance. However, the pooled analysis (1,085 cases and 1,088 controls) showed association with two miRNA clusters: miR-133b/miR-206 (rs16882131, permP = 0.037) and miR-17/miR-18a/miR-19a/miR-20a/miR-19b-1/miR92a-1 (rs6492538, permP = 0.019). Both miR-133b and miR-206 regulate the MET gene, previously associated with ASD. Rare variant analysis identified mutations in several miRNA genes, among them miR-541, a brain-specific miRNA that regulates SYN1, found mutated in ASD.

CONCLUSIONS

Although our results do not establish a clear role for miRNAs in ASD, we pinpointed a few candidate genes. Further exome and GWAS studies are warranted to get more insight into their potential contribution to the disorder.

MicroRNA and Posttranscriptional Dysregulation in Psychiatry

Psychiatric syndromes, including schizophrenia, mood disorders, and autism spectrum disorders, are characterized by a complex range of symptoms, including psychosis, depression, mania, and cognitive deficits. Although the mechanisms driving pathophysiology are complex and remain largely unknown, advances in the understanding of gene association and gene networks are providing significant clues to their etiology. In recent years, small noncoding RNA molecules known as microRNA (miRNA) have emerged as potential players in the pathophysiology of mental illness. These small RNAs regulate hundreds of target transcripts by modifying their stability and translation on a broad scale, influencing entire gene networks in the process. There is evidence to suggest that numerous miRNAs are dysregulated in postmortem neuropathology of neuropsychiatric disorders, and there is strong genetic support for association of miRNA genes and their targets with these conditions. This review presents the accumulated evidence linking miRNA dysregulation and dysfunction with schizophrenia, bipolar disorder, major depressive disorder, and autism spectrum disorders and the potential of miRNAs as biomarkers or therapeutics for these disorders. We further assess the functional roles of some outstanding miRNAs associated with these conditions and how they may be influencing the development of psychiatric symptoms.

Investigation of Gene Regulatory Networks Associated with Autism Spectrum Disorder Based on MiRNA Expression in China

Autism spectrum disorder (ASD) comprise a group of neurodevelopmental disorders characterized by deficits in social and communication capacities and repetitive behaviors. Increasing neuroscientific evidence indicates that the neuropathology of ASD is widespread and involves epigenetic regulation in the brain. Differentially expressed miRNAs in the peripheral blood from autism patients were identified by high-throughput miRNA microarray analyses. Five of these miRNAs were confirmed through quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis. A search for candidate target genes of the five confirmed miRNAs was performed through a Kyoto encyclopedia of genes and genomes (KEGG) biological pathways and Gene Ontology enrichment analysis of gene function to identify gene regulatory networks. To the best of our knowledge, this study provides the first global miRNA expression profile of ASD in China. The differentially expressed miR-34b may potentially explain the higher percentage of male ASD patients, and the aberrantly expressed miR-103a-3p may contribute to the abnormal ubiquitin-mediated proteolysis observed in ASD.

An update on the epigenetics of psychotic diseases and autism

The examination of potential roles of epigenetic alterations in the pathogenesis of psychotic diseases have become an essential alternative in recent years as genetic studies alone are yet to uncover major gene(s) for psychosis. Here, we describe the current state of knowledge from the gene-specific and genome-wide studies of postmortem brain and blood cells indicating that aberrant DNA methylation, histone modifications and dysregulation of micro-RNAs are linked to the pathogenesis of mental diseases. There is also strong evidence supporting that all classes of psychiatric drugs modulate diverse features of the epigenome. While comprehensive environmental and genetic/epigenetic studies are uncovering the origins, and the key genes/pathways affected in psychotic diseases, characterizing the epigenetic effects of psychiatric drugs may help to design novel therapies in psychiatry.

microRNA and Autism

Autism is a complex neurodevelopmental disorder characterized by deficiencies in social interaction and communication, and by repetitive and stereotyped behaviors. According to a recent report, the prevalence of this pervasive developmental disorder has risen to 1 in 88. This will have enormous public health implications in the future, and has necessitated the need to discover predictive biomarkers that could index for autism before the onset of symptoms. microRNAs (miRNAs) are small, noncoding RNAs that regulate gene expression at the posttranscriptional level. They have recently emerged as prominent epigenetic regulators of various cellular processes including neurodevelopment. They are abundantly present in the brain, and their dysfunction has been implicated in an array of neuropathological conditions including autism. miRNAs, previously known to be expressed only in cells and tissues, have also been detected in extracellular body fluids such as serum, plasma, saliva, and urine. Altered expression of cellular and circulating miRNAs have been observed in autistic individuals compared to healthy controls. miRNAs are now being considered as potential targets for the development of novel therapeutic strategies for autism.

Current Update on Synopsis of miRNA Dysregulation in Neurological Disorders

Aberrant expression of microRNAs (miRNAs) has been implicated in various neurological disorders (NDs) of the central nervous system such as Alzheimer disease, Parkinson's disease, Huntington disease, amyotrophic lateral sclerosis, schizophrenia and autism. If dysregulated miRNAs are identified in patients suffering from NDs, this may serve as a biomarker for the earlier diagnosis and monitoring of disease progression. Identifying the role of miRNAs in normal cellular processes and understanding how dysregulated miRNA expression is responsible for their neurological effects is also critical in the development of new therapeutic strategies for NDs. miRNAs hold great promise from a therapeutic point of view especially if it can be proved that a single miRNA has the ability to influence several target genes, making it possible for the researchers to potentially modify a whole disease phenotype by modulating a single miRNA molecule. Hence, better understanding of the mechanisms by which miRNA play a role in the pathogenesis of NDs may provide novel targets to scientists and researchers for innovative therapies.

Coding and noncoding expression patterns associated with rare obesity-related disorders: Prader-Willi and Alström syndromes

Obesity is accompanied by hyperphagia in several classical genetic obesity-related syndromes that are rare, including Prader-Willi syndrome (PWS) and Alström syndrome (ALMS). We compared coding and noncoding gene expression in adult males with PWS, ALMS, and nonsyndromic obesity relative to nonobese males using readily available lymphoblastoid cells to identify disease-specific molecular patterns and disturbed mechanisms in obesity. We found 231 genes upregulated in ALMS compared with nonobese males, but no genes were found to be upregulated in obese or PWS males and 124 genes were downregulated in ALMS. The metallothionein gene (MT1X) was significantly downregulated in ALMS, in common with obese males. Only the complex SNRPN locus was disturbed (downregulated) in PWS along with several downregulated small nucleolar RNAs (snoRNAs) in the 15q11-q13 region (SNORD116, SNORD109B, SNORD109A, SNORD107). Eleven upregulated and ten downregulated snoRNAs targeting multiple genes impacting rRNA processing, developmental pathways, and associated diseases were found in ALMS. Fifty-two miRNAs associated with multiple, overlapping gene expression disturbances were upregulated in ALMS, and four were shared with obese males but not PWS males. For example, seven passenger strand microRNAs (miRNAs) (miR-93*, miR-373*, miR-29b-2*, miR-30c-1*, miR27a*, miR27b*, and miR-149*) were disturbed in association with six separate downregulated target genes (CD68, FAM102A, MXI1, MYO1D, TP53INP1, and ZRANB1). Cell cycle (eg, PPP3CA), transcription (eg, POLE2), and development may be impacted by upregulated genes in ALMS, while downregulated genes were found to be involved with metabolic processes (eg, FABP3), immune responses (eg, IL32), and cell signaling (eg, IL1B). The high number of gene and noncoding RNA disturbances in ALMS contrast with observations in PWS and males with nonsyndromic obesity and may reflect the progressing multiorgan pathology of the ALMS disease process.

MicroRNAs in Schizophrenia: Implications for Synaptic Plasticity and Dopamine-Glutamate Interaction at the Postsynaptic Density. New Avenues for Antipsychotic Treatment Under a Theranostic Perspective

Despite dopamine-glutamate aberrant interaction that has long been considered a relevant landmark of psychosis pathophysiology, several aspects of these two neurotransmitters reciprocal interaction remain to be defined. The emerging role of postsynaptic density (PSD) proteins at glutamate synapse as a molecular "lego" making a functional hub where different signals converge may add a new piece of information to understand how dopamine-glutamate interaction may work with regard to schizophrenia pathophysiology and treatment. More recently, compelling evidence suggests a relevant role for microRNA (miRNA) as a new class of dopamine and glutamate modulators with regulatory functions in the reciprocal interaction of these two neurotransmitters. Here, we aimed at addressing the following issues: (i) Do miRNAs have a role in schizophrenia pathophysiology in the context of dopamine-glutamate aberrant interaction? (ii) If miRNAs are relevant for dopamine-glutamate interaction, at what level this modulation takes place? (iii) Finally, will this knowledge open the door to innovative diagnostic and therapeutic tools? The biogenesis of miRNAs and their role in synaptic plasticity with relevance to schizophrenia will be considered in the context of dopamine-glutamate interaction, with special focus on miRNA interaction with PSD elements. From this framework, implications both for biomarkers identification and potential innovative interventions will be considered.

MicroRNA-132, -134, and -138: a microRNA troika rules in neuronal dendrites

Dendritic mRNA transport and local translation in the postsynaptic compartment play an important role in synaptic plasticity, learning and memory. Local protein synthesis at the synapse has to be precisely orchestrated by a plethora of factors including RNA binding proteins as well as microRNAs, an extensive class of small non-coding RNAs. By binding to complementary sequences in target mRNAs, microRNAs fine-tune protein synthesis and thereby represent critical regulators of gene expression at the post-transcriptional level. Research over the last years identified an entire network of dendritic microRNAs that fulfills an essential role in synapse development and physiology. Recent studies provide evidence that these small regulatory molecules are highly regulated themselves, at the level of expression as well as function. The importance of microRNAs for correct function of the nervous system is reflected by an increasing number of studies linking dysregulation of microRNA pathways to neurological disorders. By focusing on three extensively studied examples (miR-132, miR-134, miR-138), this review will attempt to illustrate the complex regulatory roles of dendritic microRNAs at the synapse and their implications for pathological conditions.

Serum microRNA profiles in children with autism

Background

As regulators of gene expression, microRNAs (miRNAs) play a key role in the transcriptional networks of the developing human brain. Circulating miRNAs in the serum and plasma are remarkably stable and are suggested to have promise as noninvasive biomarkers for neurological and neurodevelopmental disorders. We examined the serum expression profiles of neurologically relevant miRNAs in autism spectrum disorder (ASD), a complex neurodevelopmental disorder characterized by multiple deficits in communication, social interaction and behavior.

Methods

Total RNA, including miRNA, was extracted from the serum samples of 55 individuals with ASD and 55 age- and sex-matched control subjects, and the mature miRNAs were selectively converted into cDNA. Initially, the expression of 125 mature miRNAs was compared between pooled control and ASD samples. The differential expression of 14 miRNAs was further validated by SYBR Green quantitative PCR of individual samples. Receiver-operating characteristic (ROC) analysis was used to evaluate the sensitivity and specificity of miRNAs. The target genes and pathways of miRNAs were predicted using DIANA mirPath software.

Results

Thirteen miRNAs were differentially expressed in ASD individuals compared to the controls. MiR-151a-3p, miR-181b-5p, miR-320a, miR-328, miR-433, miR-489, miR-572, and miR-663a were downregulated, while miR-101-3p, miR-106b-5p, miR-130a-3p, miR-195-5p, and miR-19b-3p were upregulated. Five miRNAs showed good predictive power for distinguishing individuals with ASD. The target genes of these miRNAs were enriched in several crucial neurological pathways.

Conclusions

This is the first study of serum miRNAs in ASD individuals. The results suggest that a set of serum miRNAs might serve as a possible noninvasive biomarker for ASD.

Mining the 3'UTR of autism-implicated genes for SNPs perturbing microRNA regulation

Autism spectrum disorder (ASD) refers to a group of childhood neurodevelopmental disorders with polygenic etiology. The expression of many genes implicated in ASD is tightly regulated by various factors including microRNAs (miRNAs), a class of noncoding RNAs ~22 nucleotides in length that function to suppress translation by pairing with 'miRNA recognition elements' (MREs) present in the 3'untranslated region (3'UTR) of target mRNAs. This emphasizes the role played by miRNAs in regulating neurogenesis, brain development and differentiation and hence any perturbations in this regulatory mechanism might affect these processes as well. Recently, single nucleotide polymorphisms (SNPs) present within 3'UTRs of mRNAs have been shown to modulate existing MREs or even create new MREs. Therefore, we hypothesized that SNPs perturbing miRNA-mediated gene regulation might lead to aberrant expression of autism-implicated genes, thus resulting in disease predisposition or pathogenesis in at least a subpopulation of ASD individuals. We developed a systematic computational pipeline that integrates data from well-established databases. By following a stringent selection criterion, we identified 9 MRE-modulating SNPs and another 12 MRE-creating SNPs in the 3'UTR of autism-implicated genes. These high-confidence candidate SNPs may play roles in ASD and hence would be valuable for further functional validation.

When less is more--microRNAs and psychiatric disorders

OBJECTIVE

MicroRNAs are small non-coding RNA molecules that regulate gene expression, including genes involved in neuronal function and plasticity that have relevance for brain function and mental health. We therefore performed a systematic review of miRNAs in general adult psychiatric disorders.

METHOD

Systematic searches in PubMed/MEDLINE and Web of Science were conducted to identify published clinical articles on microRNAs in general adult psychiatric disorders. We also reviewed references from included articles.

RESULTS

There is mounting evidence of microRNAs' regulatory roles in a number of central nervous system processes, including neurogenesis and synaptic plasticity. The majority of clinical studies of microRNAs in psychiatric disorders are in schizophrenia, where a number of specific microRNAs have been identified in separate studies. There is some evidence of marked downregulation of some microRNAs in affective disorders. Treatment with antidepressants appears to upregulate microRNA levels. There is currently little evidence from human studies in anxiety, addiction or other psychiatric disorders.

CONCLUSION

MicroRNA research in psychiatry is currently in a nascent period, but represents an emerging and exciting area, with the potential to clarify molecular mechanisms of disease and identify novel biomarkers and therapeutic agents.

Assessing the impact of copy number variants on miRNA genes in autism by Monte Carlo simulation

Autism Spectrum Disorders (ASDs) are childhood neurodevelopmental disorders with complex genetic origins. Previous studies have investigated the role of de novo Copy Number Variants (CNVs) and microRNAs as important but distinct etiological factors in ASD. We developed a novel computational procedure to assess the potential pathogenic role of microRNA genes overlapping de novo CNVs in ASD patients. Here we show that for chromosomes # 1, 2 and 22 the actual number of miRNA loci affected by de novo CNVs in patients was found significantly higher than that estimated by Monte Carlo simulation of random CNV events. Out of 24 miRNA genes over-represented in CNVs from these three chromosomes only hsa-mir-4436b-1 and hsa-mir-4436b-2 have not been detected in CNVs from non-autistic subjects as reported in the Database of Genomic Variants. Altogether the results reported in this study represent a first step towards a full understanding of how a dysregulated expression of the 24 miRNAs genes affect neurodevelopment in autism. We also propose that the procedure used in this study can be effectively applied to CNVs/miRNA genes association data in other genomic disorders beyond autism.

A direct molecular link between the autism candidate gene RORa and the schizophrenia candidate MIR137

Retinoic acid-related orphan receptor alpha gene (RORa) and the microRNA MIR137 have both recently been identified as novel candidate genes for neuropsychiatric disorders. RORa encodes a ligand-dependent orphan nuclear receptor that acts as a transcriptional regulator and miR-137 is a brain enriched small non-coding RNA that interacts with gene transcripts to control protein levels. Given the mounting evidence for RORa in autism spectrum disorders (ASD) and MIR137 in schizophrenia and ASD, we investigated if there was a functional biological relationship between these two genes. Herein, we demonstrate that miR-137 targets the 3'UTR of RORa in a site specific manner. We also provide further support for MIR137 as an autism candidate by showing that a large number of previously implicated autism genes are also putatively targeted by miR-137. This work supports the role of MIR137 as an ASD candidate and demonstrates a direct biological link between these previously unrelated autism candidate genes.

Horizons of psychiatric genetics and epigenetics: where are we and where are we heading?

Today multinational studies using genome-wide association scan (GWAS) for >1000,000 polymorphisms on >100,000 cases with major psychiatric diseases versus controls, combined with next-generation sequencing have found ~100 genetic polymorphisms associated with schizophrenia (SCZ), bipolar disorder (BD), autism, attention deficit and hyperactivity disorder (ADHD), etc. However, the effect size of each genetic mutation has been generally low (<1%), and altogether could portray a tiny fraction of these mental diseases. Furthermore, none of these polymorphisms was specific to disease phenotypes indicating that they are simply genetic risk factors rather than causal mutations. The lack of identification of the major gene(s) in huge genetic studies increased the tendency for reexamining the roles of environmental factors in psychiatric and other complex diseases. However, this time at cellular/molecular levels mediated by epigenetic mechanisms that are heritable, but reversible while interacting with the environment. Now, gene-specific or whole-genome epigenetic analyses have introduced hundreds of aberrant epigenetic marks in the blood or brain of individuals with psychiatric diseases that include aberrations in DNA methylation, histone modifications and microRNA expression. Interestingly, most of the current psychiatric drugs such as valproate, lithium, antidepressants, antipsychotics and even electroconvulsive therapy (ECT) modulate epigenetic codes. The existing data indicate that, the impacts of environment/nurture, including the uterine milieu and early-life events might be more significant than genetic/nature in most psychiatric diseases. The lack of significant results in large-scale genetic studies led to revise the bolded roles of genetics and now we are at the turning point of genomics for reconsidering environmental factors that through epigenetic mechanisms may impact the brain development/functions causing disease phenotypes.

Network signatures of cellular immortalization in human lymphoblastoid cell lines

Human lymphoblastoid cell line (LCL) has been used as an in vitro cell model in genetic and pharmacogenomic studies, as well as a good model for studying gene expression regulatory machinery using integrated genomic analyses. In this study, we aimed to identify biological networks of LCL immortalization from transcriptomic profiles of microRNAs and their target genes in LCLs. We first selected differentially expressed genes (DEGs) and microRNAs (DEmiRs) between early passage LCLs (eLCLs) and terminally differentiated late passage LCLs (tLCLs). The in silico and correlation analysis of these DEGs and DEmiRs revealed that 1098 DEG-DEmiR pairs were found to be positively (n=591 pairs) or negatively (n=507 pairs) correlated with each other. More than 41% of DEGs are possibly regulated by miRNAs in LCL immortalizations. The target DEGs of DEmiRs were enriched for cellular functions associated with apoptosis, immune response, cell death, JAK-STAT cascade and lymphocyte activation while non-miRNA target DEGs were over-represented for basic cell metabolisms. The target DEGs correlated negatively with miR-548a-3p and miR-219-5p were significantly associated with protein kinase cascade, and the lymphocyte proliferation and apoptosis, respectively. In addition, the miR-106a and miR-424 clusters located in the X chromosome were enriched in DEmiR-mRNA pairs for LCL immortalization. In this study, the integrated transcriptomic analysis of LCLs could identify functional networks of biologically active microRNAs and their target genes involved in LCL immortalization.

Neuregulin-1 alpha, the underestimated molecule: emerging new roles in normal brain function and the pathophysiology of schizophrenia?

We comment here, from a schizophrenia research perspective, on a recent paper of Ghahramani Seno et al., which clearly shows that the splice variant neuregulin-1 alpha is able to regulate multiple genes involved in phosphorylation, acetylation, and generation of splice variants.

Evaluation of single nucleotide polymorphisms in the miR-183-96-182 cluster in adulthood attention-deficit and hyperactivity disorder (ADHD) and substance use disorders (SUDs)

Attention deficit-hyperactivity disorder (ADHD) is a neuropsychiatric disorder characterized by inappropriate and impaired levels of hyperactivity, impulsivity and inattention. Around 75% of adults with ADHD show comorbidity with other psychiatric disorders such as disruptive behavior disorders or substance use disorders (SUDs). Recently, there has been growing interest in studying the role of microRNAs (miRNAs) in the susceptibility to complex disorders. Interestingly, converging evidence suggests that single nucleotide polymorphisms (SNPs) within miRNAs or miRNA target sites may modulate the miRNA-mediated regulation of gene expression through the alteration of the miRNA maturation, structure or expression pattern as well as the silencing mechanisms of target genes. Genetic studies and animal models support the involvement of the serotonin receptor (HTR1B) in ADHD. We evaluated the contribution of one SNP in the miR-96 target site at HTR1B and eight tagSNPs within the genomic region containing this miRNA in 695 adults with ADHD (266 and 396 subjects with and without comorbid SUD, respectively), 403 subjects with SUD without life-time diagnosis of ADHD and 485 sex-matched controls from Spain. Single and multiple marker analyses revealed association between two SNPs located at the 3' region of miR-96 (rs2402959 and rs6965643) and ADHD without SUD. Our results provide preliminary evidence for the contribution of two sequence variants at the miR-183-96-182 cluster to ADHD without comorbid SUD, and emphasize the need to take comorbidities into account in genetic studies to minimize the effect of heterogeneity and to clarify these complex phenotypes.

miRNA and miRNA target genes in copy number variations occurring in individuals with intellectual disability

Background

MicroRNAs (miRNAs) are a family of short, non-coding RNAs modulating expression of human protein coding genes (miRNA target genes). Their dysfunction is associated with many human diseases, including neurodevelopmental disorders. It has been recently shown that genomic copy number variations (CNVs) can cause aberrant expression of integral miRNAs and their target genes, and contribute to intellectual disability (ID).

Results

To better understand the CNV-miRNA relationship in ID, we investigated the prevalence and function of miRNAs and miRNA target genes in five groups of CNVs. Three groups of CNVs were from 213 probands with ID (24 de novo CNVs, 46 familial and 216 common CNVs), one group of CNVs was from a cohort of 32 cognitively normal subjects (67 CNVs) and one group of CNVs represented 40 ID related syndromic regions listed in DECIPHER (30 CNVs) which served as positive controls for CNVs causing or predisposing to ID. Our results show that 1). The number of miRNAs is significantly higher in de novo or DECIPHER CNVs than in familial or common CNV subgroups (P < 0.01). 2). miRNAs with brain related functions are more prevalent in de novo CNV groups compared to common CNV groups. 3). More miRNA target genes are found in de novo, familial and DECIPHER CNVs than in the common CNV subgroup (P < 0.05). 4). The MAPK signaling cascade is found to be enriched among the miRNA target genes from de novo and DECIPHER CNV subgroups.

Conclusions

Our findings reveal an increase in miRNA and miRNA target gene content in de novo versus common CNVs in subjects with ID. Their expression profile and participation in pathways support a possible role of miRNA copy number change in cognition and/or CNV-mediated developmental delay. Systematic analysis of expression/function of miRNAs in addition to coding genes integral to CNVs could uncover new causes of ID.

Protein tyrosine phosphatases PTPδ, PTPσ, and LAR: presynaptic hubs for synapse organization

Synapse development requires differentiation of presynaptic neurotransmitter release sites and postsynaptic receptive apparatus coordinated by synapse organizing proteins. In addition to the well-characterized neurexins, recent studies identified presynaptic type IIa receptor-type protein tyrosine phosphatases (RPTPs) as mediators of presynaptic differentiation and triggers of postsynaptic differentiation, thus extending the roles of RPTPs from axon outgrowth and guidance. Similarly to neurexins, RPTPs exist in multiple isoforms generated by alternative splicing that interact in a splice-selective code with diverse postsynaptic partners. The parallel RPTP and neurexin hub design facilitates synapse self-assembly through cooperation, pairs presynaptic similarity with postsynaptic diversity, and balances excitation with inhibition. Upon mutation of individual genes in neuropsychiatric disorders, imbalance of this synaptic organizing network may contribute to impaired cognitive function.

Increased gene expression of FOXP1 in patients with autism spectrum disorders

Background

Comparative gene expression profiling analysis is useful in discovering differentially expressed genes associated with various diseases, including mental disorders. Autism spectrum disorders (ASD) are a group of complex childhood-onset neurodevelopmental and genetic disorders characterized by deficits in language development and verbal communication, impaired reciprocal social interaction, and the presence of repetitive behaviors or restricted interests. The study aimed to identify novel genes associated with the pathogenesis of ASD.

Methods

We conducted comparative total gene expression profiling analysis of lymphoblastoid cell lines (LCL) between 16 male patients with ASD and 16 male control subjects to screen differentially expressed genes associated with ASD. We verified one of the differentially expressed genes, FOXP1, using real-time quantitative PCR (RT-qPCR) in a sample of 83 male patients and 83 male controls that included the initial 16 male patients and male controls, respectively.

Results

A total of 252 differentially expressed probe sets representing 202 genes were detected between the two groups, including 89 up- and 113 downregulated genes in the ASD group. RT-qPCR verified significant elevation of the FOXP1 gene transcript of LCL in a sample of 83 male patients (10.46 ± 11.34) compared with 83 male controls (5.17 ± 8.20, P = 0.001).

Conclusions

Comparative gene expression profiling analysis of LCL is useful in discovering novel genetic markers associated with ASD. Elevated gene expression of FOXP1 might contribute to the pathogenesis of ASD.

Clinical trial registration

Identifier: NCT00494754

AKAPs integrate genetic findings for autism spectrum disorders

Autism spectrum disorders (ASDs) are highly heritable, and six genome-wide association studies (GWASs) of ASDs have been published to date. In this study, we have integrated the findings from these GWASs with other genetic data to identify enriched genetic networks that are associated with ASDs. We conducted bioinformatics and systematic literature analyses of 200 top-ranked ASD candidate genes from five published GWASs. The sixth GWAS was used for replication and validation of our findings. Further corroborating evidence was obtained through rare genetic variant studies, that is, exome sequencing and copy number variation (CNV) studies, and/or other genetic evidence, including candidate gene association, microRNA and gene expression, gene function and genetic animal studies. We found three signaling networks regulating steroidogenesis, neurite outgrowth and (glutamatergic) synaptic function to be enriched in the data. Most genes from the five GWASs were also implicated--independent of gene size--in ASDs by at least one other line of genomic evidence. Importantly, A-kinase anchor proteins (AKAPs) functionally integrate signaling cascades within and between these networks. The three identified protein networks provide an important contribution to increasing our understanding of the molecular basis of ASDs. In addition, our results point towards the AKAPs as promising targets for developing novel ASD treatments.

Big effects of small RNAs: a review of microRNAs in anxiety

Epigenetic and regulatory elements provide an additional layer of complexity to the heterogeneity of anxiety disorders. MicroRNAs (miRNAs) are a class of small, noncoding RNAs that have recently drawn interest as epigenetic modulators of gene expression in psychiatric disorders. miRNAs elicit their effects by binding to target messenger RNAs (mRNAs) and hindering translation or accelerating degradation. Considering their role in neuronal differentiation and synaptic plasticity, miRNAs have opened up new investigative avenues in the aetiology and treatment of anxiety disorders. In this review, we provide a thorough analysis of miRNAs, their targets and their functions in the central nervous system (CNS), focusing on their role in anxiety disorders. The involvement of miRNAs in CNS functions (such as neurogenesis, neurite outgrowth, synaptogenesis and synaptic and neural plasticity) and their intricate regulatory role under stressful conditions strongly support their importance in the aetiology of anxiety disorders. Furthermore, miRNAs could provide new avenues for the development of therapeutic targets in anxiety disorders.

Molecular mechanisms of peripheral nerve regeneration: emerging roles of microRNAs

MicroRNAs are small non-coding RNAs that suppress gene expression through target mRNA degradation or translation repression. Recent studies suggest that miRNA plays an important role in multiple physiological and pathological processes in the nervous system. In this review article, we described what is currently known about the mechanisms in peripheral nerve regeneration on cellular and molecular levels. Recently, changes in microRNA expression profiles have been detected in different injury models, and emerging evidence strongly indicates that these changes promote neurons to survive by shifting their physiology from maintaining structure and supporting synaptic transmission towards a regenerative phenotype. We reviewed the putative mechanisms involved in miRNA mediated post-transcriptional regulation and pointed out several areas where future research is necessary to advance our understanding of how targeting miRNA machinery can be used as a therapeutic approach for treating nerve injuries.

The expanding genomic landscape of autism: discovering the 'forest' beyond the 'trees'

Autism spectrum disorders are neurodevelopmental disorders characterized by significant deficits in reciprocal social interactions, impaired communication and restricted, repetitive behaviors. As autism spectrum disorders are among the most heritable of neuropsychiatric disorders, much of autism research has focused on the search for genetic variants in protein-coding genes (i.e., the 'trees'). However, no single gene can account for more than 1% of the cases of autism spectrum disorders. Yet, genome-wide association studies have often identified statistically significant associations of genetic variations in regions of DNA that do not code for proteins (i.e., intergenic regions). There is increasing evidence that such noncoding regions are actively transcribed and may participate in the regulation of genes, including genes on different chromosomes. This article summarizes evidence that suggests that the research spotlight needs to be expanded to encompass far-reaching gene-regulatory mechanisms that include a variety of epigenetic modifications, as well as noncoding RNA (i.e., the 'forest'). Given that noncoding RNA represents over 90% of the transcripts in most cells, we may be observing just the 'tip of the iceberg' or the 'edge of the forest' in the genomic landscape of autism.

TCF4 (e2-2; ITF2): a schizophrenia-associated gene with pleiotropic effects on human disease

Common SNPs in the transcription factor 4 (TCF4; ITF2, E2-2, SEF-2) gene, which encodes a basic Helix-Loop-Helix (bHLH) transcription factor, are associated with schizophrenia, conferring a small increase in risk. Other common SNPs in the gene are associated with the common eye disorder Fuch's corneal dystrophy, while rare, mostly de novo inactivating mutations cause Pitt-Hopkins syndrome. In this review, we present a systematic bioinformatics and literature review of the genomics, biological function and interactome of TCF4 in the context of schizophrenia. The TCF4 gene is present in all vertebrates, and although protein length varies, there is high conservation of primary sequence, including the DNA binding domain. Humans have a unique leucine-rich nuclear export signal. There are two main isoforms (A and B), as well as complex splicing generating many possible N-terminal amino acid sequences. TCF4 is highly expressed in the brain, where plays a role in neurodevelopment, interacting with class II bHLH transcription factors Math1, HASH1, and neuroD2. The Ca(2+) sensor protein calmodulin interacts with the DNA binding domain of TCF4, inhibiting transcriptional activation. It is also the target of microRNAs, including mir137, which is implicated in schizophrenia. The schizophrenia-associated SNPs are in linkage disequilibrium with common variants within putative DNA regulatory elements, suggesting that regulation of expression may underlie association with schizophrenia. Combined gene co-expression analyses and curated protein-protein interaction data provide a network involving TCF4 and other putative schizophrenia susceptibility genes. These findings suggest new opportunities for understanding the molecular basis of schizophrenia and other mental disorders.

Characteristics and predictive value of blood transcriptome signature in males with autism spectrum disorders

Autism Spectrum Disorders (ASD) is a spectrum of highly heritable neurodevelopmental disorders in which known mutations contribute to disease risk in 20% of cases. Here, we report the results of the largest blood transcriptome study to date that aims to identify differences in 170 ASD cases and 115 age/sex-matched controls and to evaluate the utility of gene expression profiling as a tool to aid in the diagnosis of ASD. The differentially expressed genes were enriched for the neurotrophin signaling, long-term potentiation/depression, and notch signaling pathways. We developed a 55-gene prediction model, using a cross-validation strategy, on a sample cohort of 66 male ASD cases and 33 age-matched male controls (P1). Subsequently, 104 ASD cases and 82 controls were recruited and used as a validation set (P2). This 55-gene expression signature achieved 68% classification accuracy with the validation cohort (area under the receiver operating characteristic curve (AUC): 0.70 [95% confidence interval [CI]: 0.62–0.77]). Not surprisingly, our prediction model that was built and trained with male samples performed well for males (AUC 0.73, 95% CI 0.65–0.82), but not for female samples (AUC 0.51, 95% CI 0.36–0.67). The 55-gene signature also performed robustly when the prediction model was trained with P2 male samples to classify P1 samples (AUC 0.69, 95% CI 0.58–0.80). Our result suggests that the use of blood expression profiling for ASD detection may be feasible. Further study is required to determine the age at which such a test should be deployed, and what genetic characteristics of ASD can be identified.

Aberrant expression of long noncoding RNAs in autistic brain

The autism spectrum disorders (ASD) have a significant hereditary component, but the implicated genetic loci are heterogeneous and complex. Consequently, there is a gap in understanding how diverse genomic aberrations all result in one clinical ASD phenotype. Gene expression studies from autism brain tissue have demonstrated that aberrantly expressed protein-coding genes may converge onto common molecular pathways, potentially reconciling the strong heritability and shared clinical phenotypes with the genomic heterogeneity of the disorder. However, the regulation of gene expression is extremely complex and governed by many mechanisms, including noncoding RNAs. Yet no study in ASD brain tissue has assessed for changes in regulatory long noncoding RNAs (lncRNAs), which represent a large proportion of the human transcriptome, and actively modulate mRNA expression. To assess if aberrant expression of lncRNAs may play a role in the molecular pathogenesis of ASD, we profiled over 33,000 annotated lncRNAs and 30,000 mRNA transcripts from postmortem brain tissue of autistic and control prefrontal cortex and cerebellum by microarray. We detected over 200 differentially expressed lncRNAs in ASD, which were enriched for genomic regions containing genes related to neurodevelopment and psychiatric disease. Additionally, comparison of differences in expression of mRNAs between prefrontal cortex and cerebellum within individual donors showed ASD brains had more transcriptional homogeneity. Moreover, this was also true of the lncRNA transcriptome. Our results suggest that further investigation of lncRNA expression in autistic brain may further elucidate the molecular pathogenesis of this disorder.

Non-Coding RNAs Regulating Morphine Function: With Emphasis on the In vivo and In vitro Functions of miR-190

Non-coding RNAs (ncRNAs), especially microRNAs, are reported to be involved in a variety of biological processes, including several processes related to drug addiction. It has been suggested that the biological functions of opioids, one typical type of addictive drugs, are regulated by ncRNAs. In the current review, we examine a variety of mechanisms through which ncRNAs could regulate μ-opioid receptor (OPRM1) activities and thereby contribute to the development of opioid addiction. Using miR-23b as an example, we present the possible ways in which ncRNA-mediated regulation of OPRM1 expression could impact opioid addiction. Using miR-190 as an example, we demonstrate the critical roles played by ncRNAs in the signal cascade from receptor to systemic responses, including the possible modulation of adult neurogenesis and in vivo contextual memory. After discussing the possible targets of ncRNAs involved in the development of opioid addiction, we summarize the mechanisms underlying the interaction between ncRNAs and opioid addiction and present suggestions for further study.