A genetic variant that disrupts MET transcription is associated with autism

Epigenetic Insights into Autism Spectrum Disorder: DNA Methylation Levels of NR3C1, ASCL1, and FOXO3 in Korean Autism Spectrum Disorder Sibling Pairs

Objective

Previous research on autism spectrum disorder (ASD) in Koreans has primarily focused on genetic diversity because of its high heritability. However, the emerging recognition of transgenerational epigenetic changes has recently shifted research attention towards epigenetic perspectives.

Methods

This study investigated the DNA methylation patterns of the promoter regions of candidate genes such as NR3C1, ASCL1, and FOXO3 in blood samples from ASD probands and their unaffected siblings. The analysis included 54 families (ASD proband group: 54; unaffected biological sibling group: 63). The diagnostic process involved screening the probands and their siblings for ASD based on the Diagnostic and Statistical Manual of Mental Disorders 5th edition. Intelligence, social ability, and medical history were thoroughly assessed using various scales and questionnaires. Genomic DNA from blood samples was analyzed using a methylation-sensitive quantitative polymerase chain reaction to examine the DNA methylation status of candidate genes.

Results

Methylation levels in candidate gene promoter regions differed significantly between the proband and sibling groups for all candidate genes. Correlation analysis between the proband and sibling groups revealed strong and significant correlations in NR3C1 and ASCL1 methylation. Additionally, in the analysis of the relationship between DNA and ASD phenotypes, FOXO3 methylation correlated with social quotient in probands, and ASCL1 methylation was associated with nonverbal communication, and daily living skills as measured by the Korean Vineland Adaptive Behavior Scale. Notably, ASCL1 methylation was significantly associated with parental age at pregnancy.

Conclusion

This study proposes DNA methylation of NR3C1, ASCL1, and FOXO3 in peripheral blood samples is a potential epigenetic biomarker of ASD.

Single-molecule imaging and molecular dynamics simulations reveal early activation of the MET receptor in cells

Embedding of cell-surface receptors into a membrane defines their dynamics but also complicates experimental characterization of their signaling complexes. The hepatocyte growth factor receptor MET is a receptor tyrosine kinase involved in cellular processes such as proliferation, migration, and survival. It is also targeted by the pathogen Listeria monocytogenes, whose invasion protein, internalin B (InlB), binds to MET, forming a signaling dimer that triggers pathogen internalization. Here we use an integrative structural biology approach, combining molecular dynamics simulations and single-molecule Förster resonance energy transfer (smFRET) in cells, to investigate the early stages of MET activation. Our simulations show that InlB binding stabilizes MET in a conformation that promotes dimer formation. smFRET reveals that the in situ dimer structure closely resembles one of two previously published crystal structures, though with key differences. This study refines our understanding of MET activation and provides a methodological framework for studying other plasma membrane receptors.

Developmental and molecular contributions to contextual fear memory emergence in mice

Cognitive impairment is a common phenotype of neurodevelopmental disorders, but how these deficits arise remains elusive. Determining the onset of discrete cognitive capabilities facilitates studies in probing mechanisms underlying their emergence. The present study analyzed the emergence of contextual fear memory persistence (7-day memory retention) and remote memory (30-day memory retention). There was a rapid transition from postnatal day (P) 20 to P21, in which memory persistence emerged in C57Bl/6 J male and female mice. Remote memory was present at P23, but expression was not robust compared to pubertal and adult mice. Previous studies reported that following deletion of the MET receptor tyrosine kinase (MET), there are fear memory deficits in adult mice and the timing of critical period plasticity is altered in the developing visual cortex, positioning MET as a regulator for onset of contextual fear memory. Sustaining Met past the normal window of peak cortical expression or deleting Met, however, did not alter the timing of emergence of persistence or remote memory capabilities during development. Fear memory in young adults, however, was disrupted. Remarkably, compared to homecage controls, the number of FOS-expressing infragranular neurons in medial prefrontal cortex (mPFC) did not increase from contextual memory formation recall of fear conditioning at P35 but exhibited enhanced activation at P90 in male and female mice. Additionally, MET-expressing neurons were preferentially recruited at P90 compared to P35 during fear memory expression. The studies demonstrate a developmental profile of contextual fear memory capabilities. Further, developmental disruption of Met leads to a delayed functional deficit that arises in young adulthood, correlated with an increase of mPFC neuron activation during fear memory recall.

Discovery of a novel cytokine signature for the diagnosis of autism spectrum disorder in young Arab children in Qatar

Background

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder characterized by impaired social interaction and communication and the occurrence of stereotyped and repetitive behaviors. Several studies have reported altered cytokine profiles in ASD and hence may serve as potential diagnostic biomarkers of the disorder. This study aims to identify diagnostic biomarkers for ASD in a well-defined study cohort in Qatar.

Methods

We measured the protein levels of 45 cytokines in the plasma samples of age- and gender-matched children (2-4 years) with ASD (n = 100) and controls (n = 60) using a Luminex multiplex assay. We compared the differences in the levels of these cytokines between the two study groups and then fitted the significantly altered cytokines into a logistic regression model to examine their diagnostic potential for ASD.

Results

We found elevated levels of IFN-γ, FGF-2, IL-1RA, and IL-13 and reduced levels of eotaxin, HGF, IL-1 alpha, IL-22, IL-9, MCP-1, SCF, SDF-1 alpha, VEGFA, and IP-10 in the plasma of children with ASD compared to controls. Furthermore, we observed that elevated levels of IFN-γ (odds ratio (OR) = 1.823; 95% (confidence interval) CI = 1.206, 2.755; p = 0.004) and FGF-2 (OR = 2.528; 95% CI = 1.457, 4.385; p < 0.001) were significantly associated with increased odds of ASD, whereas reduced levels of eotaxin (OR = 0.350; 95% CI = 0.160, 0.765; p = 0.008) and HGF (OR = 0.220; 95% CI = 0.070, 0.696; p = 0.010) were significantly associated with lower odds of ASD relative to controls. The combination of these four cytokines revealed an area under the curve (ROC-AUC) of 0.829 (95% CI = 0.767, 0.891; p < 0.001), which demonstrates the diagnostic accuracy of the four-cytokine signature.

Conclusions

Our results identified a panel of cytokines that could discriminate between children with ASD and controls in Qatar. In addition, our findings support the predominance of a Th1 immune phenotype in ASD children and emphasize the need to validate these results in larger populations.

Developmental and molecular contributions to contextual fear memory emergence in mice

Cognitive impairment is a common phenotype of neurodevelopmental disorders, but how these deficits arise remains elusive. Determining the onset of discrete cognitive capabilities facilitates studies in probing mechanisms underlying their emergence. The present study analyzed the emergence of contextual fear memory persistence (7-day memory retention) and remote memory (30-day memory retention). There was a rapid transition from postnatal day (P) 20 to P21, in which memory persistence emerged in C57Bl/6J male and female mice. Remote memory was present at P23, but expression was not robust compared to pubertal and adult mice. Previous studies reported that following deletion of the MET receptor tyrosine kinase (MET), there are fear memory deficits in adult mice and the timing of critical period plasticity is altered in the developing visual cortex, positioning MET as a regulator for onset of contextual fear memory. Sustaining Met past the normal window of peak cortical expression or deleting Met, however, did not alter the timing of emergence of persistence or remote memory capabilities during development. Fear memory in young adults, however, was disrupted. Remarkably, compared to homecage controls, the number of FOS-expressing infragranular neurons in medial prefrontal cortex (mPFC) did not increase from contextual memory formation recall of fear conditioning at P35 but exhibited enhanced activation at P90 in male and female mice. Additionally, MET-expressing neurons were preferentially recruited at P90 compared to P35 during fear memory expression. The studies demonstrate a developmental profile of contextual fear memory capabilities. Further, developmental disruption of Met leads to a delayed functional deficit that arises in young adulthood, correlated with an increase of mPFC neuron activation during fear memory recall.

Ex vivo exposure to polybrominated diphenyl ether (PBDE) selectively affects the immune response in autistic children

Children on the autism spectrum have been shown to have immune dysregulation that often correlates with behavioral deficits. The role of the post-natal environment in this dysregulation is an area of active investigation. We examined the association between plasma levels of polybrominated diphenyl ether (PBDE) and immune cell function in age-matched autistic children and non-autistic controls. Plasma from children on the autism spectrum (n = 38) and typically developing controls (TD; n = 60) were analyzed for 14 major PBDE congeners. Cytokine/chemokine production was measured in peripheral blood mononuclear cell (PBMC) supernatants with and without ex vivo BDE-49 exposure. Total plasma concentration (∑PBDE14) and individual congener levels were also correlated with T cell function. ∑PBDE14 did not differ between diagnostic groups but correlated with reduced immune function in children on the autism spectrum. In autistic children, IL-2 and IFN-γ production was reduced in association with several individual BDE congeners, especially BDE-49 (p = 0.001). Furthermore, when PBMCs were exposed ex vivo to BDE-49, cells from autistic children produced elevated levels of IL-6, TNF-α, IL-1β, MIP-1α and MCP-1 (p < 0.05). Therefore, despite similar plasma levels of PBDE, these data suggest that PBMC function was differentially impacted in the context of several PBDE congeners in autistic children relative to TD children where increased body burden of PBDE significantly correlated with a suppressed immune response in autistic children but not TD controls. Further, acute ex vivo exposure of PBMCs to BDE-49 stimulates an elevated cytokine response in AU cases versus a depressed response in TD controls. These data suggest that exposure to the toxicant BDE-49 differentially impacts immune cell function in autistic children relative to TD children providing evidence for an underlying association between susceptibility to PBDE exposure and immune anomalies in children on the autism spectrum.

Neuroimaging genetics approaches to identify new biomarkers for the early diagnosis of autism spectrum disorder

Autism-spectrum disorders (ASDs) are developmental disabilities that manifest in early childhood and are characterized by qualitative abnormalities in social behaviors, communication skills, and restrictive or repetitive behaviors. To explore the neurobiological mechanisms in ASD, extensive research has been done to identify potential diagnostic biomarkers through a neuroimaging genetics approach. Neuroimaging genetics helps to identify ASD-risk genes that contribute to structural and functional variations in brain circuitry and validate biological changes by elucidating the mechanisms and pathways that confer genetic risk. Integrating artificial intelligence models with neuroimaging data lays the groundwork for accurate diagnosis and facilitates the identification of early diagnostic biomarkers for ASD. This review discusses the significance of neuroimaging genetics approaches to gaining a better understanding of the perturbed neurochemical system and molecular pathways in ASD and how these approaches can detect structural, functional, and metabolic changes and lead to the discovery of novel biomarkers for the early diagnosis of ASD.

A human leukocyte antigen imputation study uncovers possible genetic interplay between gut inflammatory processes and autism spectrum disorders

Autism spectrum disorders (ASD) are neurodevelopmental conditions that are for subsets of individuals, underpinned by dysregulated immune processes, including inflammation, autoimmunity, and dysbiosis. Consequently, the major histocompatibility complex (MHC)-hosted human leukocyte antigen (HLA) has been implicated in ASD risk, although seldom investigated. By utilizing a GWAS performed by the EU-AIMS consortium (LEAP cohort), we compared HLA and MHC genetic variants, single nucleotide polymorphisms (SNP), and haplotypes in ASD individuals, versus typically developing controls. We uncovered six SNPs, namely rs9268528, rs9268542, rs9268556, rs14004, rs9268557, and rs8084 that crossed the Bonferroni threshold, which form the underpinnings of 3 independent genetic pathways/blocks that differentially associate with ASD. Block 1 (rs9268528-G, rs9268542-G, rs9268556-C, and rs14004-A) afforded protection against ASD development, whilst the two remaining blocks, namely rs9268557-T, and rs8084-A, associated with heightened risk. rs8084 and rs14004 mapped to the HLA-DRA gene, whilst the four other SNPs located in the BTNL2 locus. Different combinations amongst BTNL2 SNPs and HLA amino acid variants or classical alleles were found either to afford protection from or contribute to ASD risk, indicating a genetic interplay between BTNL2 and HLA. Interestingly, the detected variants had transcriptional and/or quantitative traits loci implications. As BTNL2 modulates gastrointestinal homeostasis and the identified HLA alleles regulate the gastrointestinal tract in celiac disease, it is proposed that the data on ASD risk may be linked to genetically regulated gut inflammatory processes. These findings might have implications for the prevention and treatment of ASD, via the targeting of gut-related processes.

Structural neuroimaging phenotypes and associated molecular and genomic underpinnings in autism: a review

Autism has been associated with differences in the developmental trajectories of multiple neuroanatomical features, including cortical thickness, surface area, cortical volume, measures of gyrification, and the gray-white matter tissue contrast. These neuroimaging features have been proposed as intermediate phenotypes on the gradient from genomic variation to behavioral symptoms. Hence, examining what these proxy markers represent, i.e., disentangling their associated molecular and genomic underpinnings, could provide crucial insights into the etiology and pathophysiology of autism. In line with this, an increasing number of studies are exploring the association between neuroanatomical, cellular/molecular, and (epi)genetic variation in autism, both indirectly and directly in vivo and across age. In this review, we aim to summarize the existing literature in autism (and neurotypicals) to chart a putative pathway from (i) imaging-derived neuroanatomical cortical phenotypes to (ii) underlying (neuropathological) biological processes, and (iii) associated genomic variation.

A potent and selective CXCR2 antagonist improves neuroimmune dysregulation through the inhibition of NF-κB and notch inflammatory signaling in the BTBR mouse model of autism

Autism comprises a broad range of neurodevelopmental disorders characterized by social communication deficits and repetitive and stereotyped behaviors. Chemokine receptor CXCR2 is expressed on neurons and is upregulated in neurological disorders. BTBR T+ Itpr3tf/J (BTBR) mice, a model for autism that shows the core features of ASD. Here, we studied the anti-inflammatory effect of a potent and selective CXCR2 antagonist SB332235 in the BTBR mice. The CXCR2 antagonist represents a promising therapeutic agent for several neuroinflammatory disorders. In this study, we investigated the effects of SB332235 administration on NF-κB-, Notch-1-, Notch-3-, GM-CSF-, MCP-1-, IL-6-, and IL-2- and TGF-β1-expressing CD40+ cells in BTBR and C57BL/6 (C57) mice in the spleen cells by flow cytometry. We further assessed the effect of SB332235 treatment on NF-κB, Notch-1, GM-CSF, MCP-1, IL-6, and IL-2 mRNA expression levels in the brain tissue by RT-PCR. We also explored the effect of SB332235 administration on NF-κB, GM-CSF, IL-6, and TGF-β1 protein expression levels in the brain tissue by western blotting. The SB332235-treated BTBR mice significantly decreases in CD40 + NF-κB+, CD40 + Notch-1+, CD40 + Notch-3+, CD40 + GM-CSF+, CD40 + MCP-1+, CD40 + IL-6+, and CD40 + IL-2+, and increases in CD40 + TGF-β1+ in the spleen cells. Our results further demonstrated that BTBR mice treated with SB332235 effectively decreased NF-κB, Notch-1, GM-CSF, MCP-1, IL-6, and IL-2, increasing TGF-β1 mRNA and protein expression levels in the brain tissue. In conclusion, these results indicate that SB332235 elicits an anti-inflammatory response by downregulating the inflammatory mediators and NF-κB/Notch inflammatory signaling in BTBR mice. This could represent a promising novel therapeutic target for autism treatment.

How cells sense and integrate information from different sources

Cell signaling is a fundamental cellular process that enables cells to sense and respond to information in their surroundings. At the molecular level, signaling is primarily carried out by transmembrane protein receptors that can initiate complex downstream signal transduction cascades to alter cellular behavior. In the human body, different cells can be exposed to a wide variety of environmental conditions, and cells express diverse classes of receptors capable of sensing and integrating different signals. Furthermore, different receptors and signaling pathways can crosstalk with each other to calibrate the cellular response. Crosstalk occurs through multiple mechanisms at different levels of signaling pathways. In this review, we discuss how cells sense and integrate different chemical, mechanical, and spatial signals as well as the mechanisms of crosstalk between pathways. To illustrate these concepts, we use a few well-studied signaling pathways, including receptor tyrosine kinases and integrin receptors. Finally, we discuss the implications of dysregulated cellular sensing on driving diseases such as cancer. This article is categorized under: Cancer > Molecular and Cellular Physiology Metabolic Diseases > Molecular and Cellular Physiology.

MACC1 promotes pancreatic cancer metastasis by interacting with the EMT regulator SNAI1

Metastasis is the dominant cause of cancer-related mortality. Metastasis-associated with colon cancer protein 1 (MACC1) has been proven to play a critical role in cancer metastasis. However, the prometastatic role of MACC1 in regulating the pancreatic cancer (PC) metastatic phenotype remains elusive. Here, we report that MACC1 is highly expressed in The Cancer Genome Atlas (TCGA) and tissue microarray (TMA) and identified as a good indicator for poor prognosis. Overexpression or knockdown of MACC1 in PC cells correspondingly promoted or inhibited pancreatic cancer cell migration and invasion in a MET proto-oncogene receptor tyrosine kinase (MET)-independent manner. Notably, knockdown of MACC1 in PC cells markedly decreased the liver metastatic lesions in a liver metastasis model. Mechanistically, MACC1 binds to the epithelial-mesenchymal transition (EMT) regulator snail family transcriptional repressor 1 (SNAI1) to drive EMT via upregulating the transcriptional activity of SNAI1, leading to the transactivation of fibronectin 1 (FN1) and the trans-repression of cadherin 1 (CDH1). Collectively, our results unveil a new mechanism by which MACC1 drives pancreatic cancer cell metastasis and suggest that the MACC1-SNAI1 complex-mediated mesenchymal transition may be a therapeutic target in pancreatic cancer.

Evidence of susceptibility to autism risks associated with early life ambient air pollution: A systematic review

BACKGROUND

Many studies have found associations between early life air pollution exposure and subsequent onset of autism spectrum disorder (ASD). However, characteristics that affect susceptibility remain unclear.

OBJECTIVE

This systematic review examined epidemiologic studies on the modifying roles of social, child, genetic and maternal characteristics in associations between prenatal and early postnatal air pollution exposure and ASD.

METHODS

A systematic literature search in PubMed and Embase was conducted. Studies that examined modifiers of the association between air pollution and ASD were included.

RESULTS

A total of 19 publications examined modifiers of the associations between early life air pollution exposures and ASD. In general, estimates of effects on risk of ASD in boys were larger than in girls (based on 11 studies). Results from studies of effects of family education (2 studies) and neighborhood deprivation (2 studies) on air pollution-ASD associations were inconsistent. Limited data (1 study) suggest pregnant women with insufficient folic acid intake might be more susceptible to ambient particulate matter less than 2.5 μm (PM2.5) and 10 μm (PM10) in aerodynamic diameter, and to nitrogen dioxide (NO2). Children of mothers with gestational diabetes had increased risk of ozone-associated ASD (1 study). Two genetic studies reported that copy number variations may amplify the effect of ozone, and MET rs1858830 CC genotype may augment effects of PM and near-roadway pollutants on ASD.

CONCLUSIONS

Child's sex, maternal nutrition or diabetes, socioeconomic factors, and child risk genotypes were reported to modify the effect of early-life air pollutants on ASD risk in the epidemiologic literature. However, the sparsity of studies on comparable modifying hypotheses precludes conclusive findings. Further research is needed to identify susceptible populations and potential targets for preventive intervention.

Genetics of glutamate and its receptors in autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental impairment characterized by deficits in social interaction skills, impaired communication, and repetitive and restricted behaviors that are thought to be due to altered neurotransmission processes. The amino acid glutamate is an essential excitatory neurotransmitter in the human brain that regulates cognitive functions such as learning and memory, which are usually impaired in ASD. Over the last several years, increasing evidence from genetics, neuroimaging, protein expression, and animal model studies supporting the notion of altered glutamate metabolism has heightened the interest in evaluating glutamatergic dysfunction in ASD. Numerous pharmacological, behavioral, and imaging studies have demonstrated the imbalance in excitatory and inhibitory neurotransmitters, thus revealing the involvement of the glutamatergic system in ASD pathology. Here, we review the effects of genetic alterations on glutamate and its receptors in ASD and the role of non-invasive imaging modalities in detecting these changes. We also highlight the potential therapeutic targets associated with impaired glutamatergic pathways.

The Cerebellar Involvement in Autism Spectrum Disorders: From the Social Brain to Mouse Models

Autism spectrum disorders (ASD) are pervasive neurodevelopmental disorders that include a variety of forms and clinical phenotypes. This heterogeneity complicates the clinical and experimental approaches to ASD etiology and pathophysiology. To date, a unifying theory of these diseases is still missing. Nevertheless, the intense work of researchers and clinicians in the last decades has identified some ASD hallmarks and the primary brain areas involved. Not surprisingly, the areas that are part of the so-called “social brain”, and those strictly connected to them, were found to be crucial, such as the prefrontal cortex, amygdala, hippocampus, limbic system, and dopaminergic pathways. With the recent acknowledgment of the cerebellar contribution to cognitive functions and the social brain, its involvement in ASD has become unmistakable, though its extent is still to be elucidated. In most cases, significant advances were made possible by recent technological developments in structural/functional assessment of the human brain and by using mouse models of ASD. Mouse models are an invaluable tool to get insights into the molecular and cellular counterparts of the disease, acting on the specific genetic background generating ASD-like phenotype. Given the multifaceted nature of ASD and related studies, it is often difficult to navigate the literature and limit the huge content to specific questions. This review fulfills the need for an organized, clear, and state-of-the-art perspective on cerebellar involvement in ASD, from its connections to the social brain areas (which are the primary sites of ASD impairments) to the use of monogenic mouse models.

Immune Dysregulation in Autism Spectrum Disorder: What Do We Know about It?

Autism spectrum disorder (ASD) is a group of complex multifactorial neurodevelopmental disorders characterized by a wide and variable set of neuropsychiatric symptoms, including deficits in social communication, narrow and restricted interests, and repetitive behavior. The immune hypothesis is considered to be a major factor contributing to autism pathogenesis, as well as a way to explain the differences of the clinical phenotypes and comorbidities influencing disease course and severity. Evidence highlights a link between immune dysfunction and behavioral traits in autism from several types of evidence found in both cerebrospinal fluid and peripheral blood and their utility to identify autistic subgroups with specific immunophenotypes; underlying behavioral symptoms are also shown. This review summarizes current insights into immune dysfunction in ASD, with particular reference to the impact of immunological factors related to the maternal influence of autism development; comorbidities influencing autism disease course and severity; and others factors with particular relevance, including obesity. Finally, we described main elements of similarities between immunopathology overlapping neurodevelopmental and neurodegenerative disorders, taking as examples autism and Parkinson Disease, respectively.

Identification of Chromosomal Regions Linked to Autism-Spectrum Disorders: A Meta-Analysis of Genome-Wide Linkage Scans

Background: Autism spectrum disorder (ASD) is a clinically and genetically heterogeneous group of pervasive neurodevelopmental disorders with a strong hereditary component. Although, genome-wide linkage scans (GWLS) and association studies (GWAS) have previously identified hundreds of ASD risk gene loci, the results remain inconclusive. Method: We performed a heterogeneity-based genome search meta-analysis (HEGESMA) of 15 genome scans of autism and ASD. Results: For strictly defined autism, data were analyzed across six separate genome scans. Region 7q22-q34 reached statistical significance in both weighted and unweighted analyses, with evidence of significantly low between-scan heterogeneity. For ASDs (data from 12 separate scans), chromosomal regions 5p15.33-5p15.1 and 15q22.32-15q26.1 reached significance in both weighted and unweighted analyses but did not reach significance for either low or high heterogeneity. Region 1q23.2-1q31.1 was significant in unweighted analyses with low between-scan heterogeneity. Finally, region 8p21.1-8q13.2 reached significant linkage peak in all our meta-analyses. When we combined all available genome scans (15), the same results were produced. Conclusions: This meta-analysis suggests that these regions should be further investigated for autism susceptibility genes, with the caveat that autism spectrum disorders have different linkage signals across genome scans, possibly because of the high genetic heterogeneity of the disease.

Gene expression associated with human brain activations in facial expression recognition

Previous studies identified some genetic loci of emotion, but few focused on human emotion-related gene expression. In this study, the facial expression recognition (FER) task-based high-resolution fMRI data of 203 subjects in the Human Connectome Project (HCP) and expression data of the six healthy human postmortem brain tissues in the Allen Human Brain Atlas (AHBA) were used to conduct a transcriptome-neuroimaging spatial association analysis. Finally, 371 genes were identified to be significantly associated with FER-related brain activations. Enrichment analyses revealed that FER-related genes were mainly expressed in the brain, especially neurons, and might be related to cell junction organization, synaptic functions, and nervous system development regulation, indicating that FER was a complex polygenetic biological process involving multiple pathways. Moreover, these genes exhibited higher enrichment for psychiatric diseases with heavy emotion impairments. This study provided new insight into understanding the FER-related biological mechanisms and might be helpful to explore treatment methods for emotion-related psychiatric disorders.

A Multi-Target and Multi-Channel Mechanism of Action for Jiawei Yinhuo Tang in the Treatment of Social Communication Disorders in Autism: Network Pharmacology and Molecular Docking Studies

BACKGROUND

Autism spectrum disorder (ASD) is a highly heterogeneous neurodevelopmental disorder with complex pathogenesis. Currently, the pathogenesis of ASD is not fully understood. Moreover, current treatments do not effectively alleviate the primary symptoms of ASD social disorder (SCDA). Jiawei Yinhuo Tang (JWYHT) is an improved version of the classic prescription Yinhuo Tang. Although this medication has been shown to improve social behavior in ASD patients, the mechanism by which it works remains unknown.

METHODS

In this study, network pharmacology bioinformatics analysis was used to identify the key targets, biological functions, and signal pathways of JWYHT in SCDA. Then, molecular docking and molecular dynamic simulation were used to validate the activity and stability of the active ingredient and the target protein during the binding process.

RESULTS

The analysis identified 157 key targets and 9 core targets of JWYHT (including proto-oncogene (FOS), caspase 3 (CASP3), mitogen-activated protein kinase-3 (MAPK3), interleukin-6 (IL6), mitogen-activated protein kinase-1 (MAPK1), tumor necrosis factor (TNF), mitogen-activated protein kinase-8 (MAPK8), AKT serine/threonine kinase 1 (AKT1), and 5-hydroxytryptamine receptor 1B (5HT1B)) in SCDA. In addition, the Kyoto Encyclopedia of Gene and Genome results, as well as the staggering network analyses, revealed 20 biological processes and 20 signal pathways targeted by JWYHT in SCDA. Finally, molecular docking analysis was used to determine the binding activity of the main active components of JWYHT to the key targets. The binding activity and stability of methyl arachidonate and MAPK8 were demonstrated using molecular dynamics simulation.

CONCLUSION

This study demonstrates that JWYHT regulates neuronal development, synaptic transmission, intestinal and cerebral inflammatory response, and other processes in SCDA.

Pleiotropic effects of BDNF on the cerebellum and hippocampus: Implications for neurodevelopmental disorders

Brain-derived neurotrophic factor (BDNF) is one of the most studied neurotrophins in the mammalian brain, essential not only to the development of the central nervous system but also to synaptic plasticity. BDNF is present in various brain areas, but highest levels of expression are seen in the cerebellum and hippocampus. After birth, BDNF acts in the cerebellum as a mitogenic and chemotactic factor, stimulating the cerebellar granule cell precursors to proliferate, migrate and maturate, while in the hippocampus BDNF plays a fundamental role in synaptic transmission and plasticity, representing a key regulator for the long-term potentiation, learning and memory. Furthermore, the expression of BDNF is highly regulated and changes of its expression are associated with both physiological and pathological conditions. The purpose of this review is to provide an overview of the current state of knowledge on the BDNF biology and its neurotrophic role in the proper development and functioning of neurons and synapses in two important brain areas of postnatal neurogenesis, the cerebellum and hippocampus. Dysregulation of BDNF expression and signaling, resulting in alterations in neuronal maturation and plasticity in both systems, is a common hallmark of several neurodevelopmental diseases, such as autism spectrum disorder, suggesting that neuronal malfunction present in these disorders is the result of excessive or reduced of BDNF support. We believe that the more the relevance of the pathophysiological actions of BDNF, and its downstream signals, in early postnatal development will be highlighted, the more likely it is that new neuroprotective therapeutic strategies will be identified in the treatment of various neurodevelopmental disorders.

Plasma metabolomics of autism spectrum disorder and influence of shared components in proband families

Prevalence of autism spectrum disorder (ASD) has been increasing in the United States in the past decades. The exact mechanisms remain enigmatic, and diagnosis of the disease still relies primarily on assessment of behavior. We first used a case-control design (75 idiopathic cases and 29 controls, enrolled at Boston Children's Hospital from 2007-2012) to identify plasma biomarkers of ASD through a metabolome-wide association study approach. Then we leveraged a family-based design (31 families) to investigate the influence of shared genetic and environmental components on the autism-associated features. Using untargeted high-resolution mass spectrometry metabolomics platforms, we detected 19 184 features. Of these, 191 were associated with ASD (false discovery rate < 0.05). We putatively annotated 30 features that had an odds ratio (OR) between <0.01 and 5.84. An identified endogenous metabolite, O-phosphotyrosine, was associated with an extremely low autism odds (OR 0.17; 95% confidence interval 0.06-0.39). We also found that glutathione metabolism was associated with ASD (P = 0.048). Correlations of the significant features between proband and parents were low (median = 0.09). Of the 30 annotated features, the median correlations within families (proband-parents) were -0.15 and 0.24 for the endogenous and exogenous metabolites, respectively. We hypothesize that, without feature identification, family-based correlation analysis of autism-associated features can be an alternative way to assist the prioritization of potentially diagnostic features. A panel of ASD diagnostic metabolic markers with high specificity could be derived upon further studies.

Disrupted Timing of MET Signaling Derails the Developmental Maturation of Cortical Circuits and Leads to Altered Behavior in Mice

The molecular regulation of the temporal dynamics of circuit maturation is a key contributor to the emergence of normal structure-function relations. Developmental control of cortical MET receptor tyrosine kinase, expressed early postnatally in subpopulations of excitatory neurons, has a pronounced impact on the timing of glutamatergic synapse maturation and critical period plasticity. Here, we show that using a controllable overexpression (cto-Met) transgenic mouse, extending the duration of MET signaling after endogenous Met is switched off leads to altered molecular constitution of synaptic proteins, persistent activation of small GTPases Cdc42 and Rac1, and sustained inhibitory phosphorylation of cofilin. These molecular changes are accompanied by an increase in the density of immature dendritic spines, impaired cortical circuit maturation of prefrontal cortex layer 5 projection neurons, and altered laminar excitatory connectivity. Two photon in vivo imaging of dendritic spines reveals that cto-Met enhances de novo spine formation while inhibiting spine elimination. Extending MET signaling for two weeks in developing cortical circuits leads to pronounced repetitive activity and impaired social interactions in adult mice. Collectively, our data revealed that temporally controlled MET signaling as a critical mechanism for controlling cortical circuit development and emergence of normal behavior.

Molecular networks of the FOXP2 transcription factor in the brain

The discovery of the FOXP2 transcription factor, and its implication in a rare severe human speech and language disorder, has led to two decades of empirical studies focused on uncovering its roles in the brain using a range of in vitro and in vivo methods. Here, we discuss what we have learned about the regulation of FOXP2, its downstream effectors, and its modes of action as a transcription factor in brain development and function, providing an integrated overview of what is currently known about the critical molecular networks.

Time-delimited signaling of MET receptor tyrosine kinase regulates cortical circuit development and critical period plasticity

Normal development of cortical circuits, including experience-dependent cortical maturation and plasticity, requires precise temporal regulation of gene expression and molecular signaling. Such regulation, and the concomitant impact on plasticity and critical periods, is hypothesized to be disrupted in neurodevelopmental disorders. A protein that may serve such a function is the MET receptor tyrosine kinase, which is tightly regulated developmentally in rodents and primates, and exhibits reduced cortical expression in autism spectrum disorder and Rett Syndrome. We found that the peak of MET expression in developing mouse cortex coincides with the heightened period of synaptogenesis, but is precipitously downregulated prior to extensive synapse pruning and certain peak periods of cortical plasticity. These results reflect a potential on-off regulatory synaptic mechanism for specific glutamatergic cortical circuits in which MET is enriched. In order to address the functional significance of the 'off' component of the proposed mechanism, we created a controllable transgenic mouse line that sustains cortical MET signaling. Continued MET expression in cortical excitatory neurons disrupted synaptic protein profiles, altered neuronal morphology, and impaired visual cortex circuit maturation and connectivity. Remarkably, sustained MET signaling eliminates monocular deprivation-induced ocular dominance plasticity during the normal cortical critical period; while ablating MET signaling leads to early closure of critical period plasticity. The results demonstrate a novel mechanism in which temporal regulation of a pleiotropic signaling protein underlies cortical circuit maturation and timing of cortical critical period, features that may be disrupted in neurodevelopmental disorders.

HGF and MET: From Brain Development to Neurological Disorders

Hepatocyte growth factor (HGF) and its tyrosine kinase receptor, encoded by the MET cellular proto-oncogene, are expressed in the nervous system from pre-natal development to adult life, where they are involved in neuronal growth and survival. In this review, we highlight, beyond the neurotrophic action, novel roles of HGF-MET in synaptogenesis during post-natal brain development and the connection between deregulation of MET expression and developmental disorders such as autism spectrum disorder (ASD). On the pharmacology side, HGF-induced MET activation exerts beneficial neuroprotective effects also in adulthood, specifically in neurodegenerative disease, and in preclinical models of cerebral ischemia, spinal cord injuries, and neurological pathologies, such as Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). HGF is a key factor preventing neuronal death and promoting survival through pro-angiogenic, anti-inflammatory, and immune-modulatory mechanisms. Recent evidence suggests that HGF acts on neural stem cells to enhance neuroregeneration. The possible therapeutic application of HGF and HGF mimetics for the treatment of neurological disorders is discussed.

Interneuron development and dysfunction

Understanding excitation and inhibition balance in the brain begins with the tale of two basic types of neurons, glutamatergic projection neurons and GABAergic interneurons. The diversity of cortical interneurons is contributed by multiple origins in the ventral forebrain, various tangential migration routes, and complicated regulations of intrinsic factors, extrinsic signals, and activities. Abnormalities of interneuron development lead to dysfunction of interneurons and inhibitory circuits, which are highly associated with neurodevelopmental disorders including schizophrenia, autism spectrum disorders, and intellectual disability. In this review, we mainly discuss recent findings on the development of cortical interneuron and on neurodevelopmental disorders related to interneuron dysfunction.

The interplay between gut microbiota and autism spectrum disorders: A focus on immunological pathways

Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders characterized by impairments in social and cognitive activities, stereotypical and repetitive behaviors and restricted areas of interest. A remarkable proportion of ASD patients represent immune dysregulation as well as gastrointestinal complications. Hence, a novel concept has recently emerged, addressing the possible intercommunication between the brain, the immune system, the gut and its commensals. Here, we provide an overview of how gut microbes and their metabolites are associated with neurobehavioral features of ASD through various immunologic mechanisms. Moreover, we discuss the potential therapeutic options that could modify these features.

5-Aminoisoquinolinone, a PARP-1 Inhibitor, Ameliorates Immune Abnormalities through Upregulation of Anti-Inflammatory and Downregulation of Inflammatory Parameters in T Cells of BTBR Mouse Model of Autism

Autism spectrum disorder (ASD) covers a range of neurodevelopmental disorders involving impairments in communication and repetitive and stereotyped patterns of behavior and reciprocal social interaction. 5-Aminoisoquinolinone (5-AIQ), a PARP-1 inhibitor, has neuroprotective and anti-inflammatory effects. We investigated the influence of 5-AIQ-treatment in BTBR T+ Itpr3tf/J (BTBR) mice as an autism model and used flow cytometry to assess the effect of 5-AIQ on FOXP3, Helios, GATA3, IL-9, IL-10 and IL-17A production by CXCR6+ and CD4+ T cells in the spleen. We also confirmed the effect of 5-AIQ treatment on expression of FOXP3, Helios, GATA3, IL-17A, IL-10, and IL-9 mRNA and protein expression levels in the brain tissue by quantitative PCR and western blotting. Our results demonstrated that 5-AIQ-treated BTBR mice had significantly increased numbers of CXCR6+FOXP3+, CXCR6+IL-10+, and CXCR6+Helios+ cells and decreased numbers of CD4+GATA3+, CD4+IL-9+, and CD4+IL-17A+ cells as compared with those in untreated BTBR mice. Our results further demonstrated that treatment with 5-AIQ in BTBR mice increased expression for FOXP3, IL-10, and Helios, and decreased expression for GATA3, IL-17A, and IL-9 mRNA. Our findings support the hypotheses that 5-AIQ has promising novel therapeutic effects on neuroimmune dysfunction in autism and is associated with modulation of Treg and Th17 cells.

Conditional knockout of MET receptor tyrosine kinase in cortical excitatory neurons leads to enhanced learning and memory in young adult mice but early cognitive decline in older adult mice

Human genetic studies established MET gene as a risk factor for autism spectrum disorders. We have previously shown that signaling mediated by MET receptor tyrosine kinase, expressed in early postnatal developing forebrain circuits, controls glutamatergic neuron morphological development, synapse maturation, and cortical critical period plasticity. Here we investigated how MET signaling affects synaptic plasticity, learning and memory behavior, and whether these effects are age-dependent. We found that in young adult (postnatal 2-3 months) Met conditional knockout (Met^fx/fx:emx1^cre, cKO) mice, the hippocampus exhibits elevated plasticity, measured by increased magnitude of long-term potentiation (LTP) and depression (LTD) in hippocampal slices. Surprisingly, in older adult cKO mice (10-12 months), LTP and LTD magnitudes were diminished. We further conducted a battery of behavioral tests to assess learning and memory function in cKO mice and littermate controls. Consistent with age-dependent LTP/LTD findings, we observed enhanced spatial memory learning in 2-3 months old young adult mice, assessed by hippocampus-dependent Morris water maze test, but impaired spatial learning in 10-12 months mice. Contextual and cued learning were further assessed using a Pavlovian fear conditioning test, which also revealed enhanced associative fear acquisition and extinction in young adult mice, but impaired fear learning in older adult mice. Lastly, young cKO mice also exhibited enhanced motor learning. Our results suggest that a shift in the window of synaptic plasticity and an age-dependent early cognitive decline may be novel circuit pathophysiology for a well-established autism genetic risk factor.

Prednisolone as Adjunctive Treatment to Risperidone in Children With Regressive Type of Autism Spectrum Disorder: A Randomized, Placebo-Controlled Trial

OBJECTIVES

This study aimed to evaluate efficacy and safety of prednisolone as an adjunctive treatment to risperidone, in children with regressive autism spectrum disorder (ASD).

METHODS

The current 12-week, randomized, single-blinded, placebo-controlled trial recruited 37 patients with regressive ASD. The participants were allocated to receive either 1 mg/kg per day prednisolone or matched placebo in addition to risperidone. The Aberrant Behavior Checklist-Community Edition (ABC-C) scale and Childhood Autism Rating Scale (CARS) were used to measure behavioral outcomes at weeks 0, 4, 8, and 12 of the study course. The primary outcome was the change in ABC-irritability subscale score, whereas the secondary outcomes were the change in scores of other ABC-C subscales, in CARS score, and in the level of inflammatory biomarkers.

RESULTS

Twenty-six patients completed the 12 weeks of study period. Repeated-measures analysis demonstrated significant effect for time-treatment interaction in the CARS (F (1, 2.23) = 13.22, P < 0.001), as well as 4 subscales of the ABC-C including: irritability (F (1, 2.12) = 3.84, P = 0.026), hyperactivity (F (1, 2.09) = 3.56, P = 0.039), lethargy (F (1, 2.18) = 31.50, P < 0.001), and stereotypy (F (1, 1.89) = 4.04, P = 0.026). However, no significant time-treatment interaction was identified for inappropriate speech subscale (F (1, 2.03) = 1.71, P = 0.191). In addition, inflammatory biomarkers were significantly decreased after 3 months of prednisolone add-on. No significant adverse event was detected during the trial.

CONCLUSIONS

Prednisolone, as an add-on to risperidone, could remarkably improve core features in children with regressive ASD.

Developmental exposure to diesel exhaust upregulates transcription factor expression, decreases hippocampal neurogenesis, and alters cortical lamina organization: relevance to neurodevelopmental disorders

Background

Exposure to traffic-related air pollution (TRAP) during development and/or in adulthood has been associated in many human studies with both neurodevelopmental and neurodegenerative diseases, such as autism spectrum disorder (ASD) and Alzheimer’s disease (AD) or Parkinson’s disease (PD).

Methods

In the present study, C57BL/6 J mice were exposed to environmentally relevant levels (250+/−50 μg/m³) of diesel exhaust (DE) or filtered air (FA) during development (E0 to PND21). The expression of several transcription factors relevant for CNS development was assessed on PND3. To address possible mechanistic underpinnings of previously observed behavioral effects of DE exposure, adult neurogenesis in the hippocampus and laminar organization of neurons in the somatosensory cortex were analyzed on PND60. Results were analyzed separately for male and female mice.

Results

Developmental DE exposure caused a male-specific upregulation of Pax6, Tbr1, Tbr2, Sp1, and Creb1 on PND3. In contrast, in both males and females, Tbr2⁺ intermediate progenitor cells in the PND60 hippocampal dentate gyrus were decreased, as an indication of reduced adult neurogenesis. In the somatosensory region of the cerebral cortex, laminar distribution of Trb1, calbindin, and parvalbumin (but not of Ctip2 or Cux1) was altered by developmental DE exposure.

Conclusions

These results provide additional evidence to previous findings indicating the ability of developmental DE exposure to cause biochemical/molecular and behavioral alterations that may be involved in neurodevelopmental disorders such as ASD.

Autism-specific maternal autoantibodies produce behavioral abnormalities in an endogenous antigen-driven mouse model of autism

Immune dysregulation has been noted consistently in individuals with autism spectrum disorder (ASD) and their families, including the presence of autoantibodies reactive to fetal brain proteins in nearly a quarter of mothers of children with ASD versus <1% in mothers of typically developing children. Our lab recently identified the peptide epitope sequences on seven antigenic proteins targeted by these maternal autoantibodies. Through immunization with these peptide epitopes, we have successfully created an endogenous, antigen-driven mouse model that ensures a constant exposure to the salient autoantibodies throughout gestation in C57BL/6J mice. This exposure more naturally mimics what is observed in mothers of children with ASD. Male and female offspring were tested using a comprehensive sequence of behavioral assays, as well as measures of health and development highly relevant to ASD. We found that MAR-ASD male and female offspring had significant alterations in development and social interactions during dyadic play. Although 3-chambered social approach was not significantly different, fewer social interactions with an estrous female were noted in the adult male MAR-ASD animals, as well as reduced vocalizations emitted in response to social cues with robust repetitive self-grooming behaviors relative to saline treated controls. The generation of MAR-ASD-specific epitope autoantibodies in female mice prior to breeding created a model that demonstrates for the first time that ASD-specific antigen-induced maternal autoantibodies produced alterations in a constellation of ASD-relevant behaviors.

Development, phenotypes of immune cells in BTBR T+Itpr3tf/J mice

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition that is characterized by a lack of social interaction, decreased verbal and non-verbal communication skills, and stereotyped repetitive behavior. There is strong evidence that a dysregulated immune response may influence neurodevelopment and thus may have a role in the development of ASD. This study focuses on the characterization of immune cell phenotypes in the BTBR T⁺Itpr3^tf/J (BTBR) mouse strain, a widely used animal model for autism research. Our study demonstrated that BTBR mice have a different immune profile compared to C57BL/6J (B6) mice, which do not display ASD-like characteristics. Thymic cells of BTBR mice have more single positive (SP) CD4⁺ and CD8⁺ T cells and fewer double positive (DP) T cells than B6 mice. The development of T cells is increased in BTBR mice with regard to the double negative (DN4) population being much higher in BTBR mice. The spleens and blood of BTBR mice also have more T helper type 1 (Th1), T helper type 2 (Th2) and T regulatory (Treg) cells compared to B6 mice. Aire expression in the thymus and spleen of BTBR mice compared to B6 mice was equivalent and lower, respectively. The mature natural killer (NK) innate immune cell population in blood and spleen is lower in BTBR than B6 mice; NK cell development is blocked prior to the double positive (DN) CD11b⁺CD27⁺ stage in BTBR mice. Since BTBR mice have more CD4⁺ T cells and elevated numbers of Th1 (T-bet⁺) and Th2 (GATA3⁺) cells, their low defense against pathogen may be explained by the lower number of NK cells and the significantly lower Th1 to Th2 ratio. The elevated number of plasma cells and autoantibodies of BTBR mice may be due to less presence and function of splenic AIRE.

7q31.2q31.31 deletion downstream of FOXP2 segregating in a family with speech and language disorder

Chromosomal 7q31 deletions have been described in individuals with variable neurodevelopmental phenotypes including speech and language impairment. These copy number variants usually encompass FOXP2, haploinsufficiency of which represents a widely acknowledged cause for specific speech and language disorders. By chromosomal microarray analysis we identified a 4.7 Mb microdeletion at 7q31.2q31.31 downstream of FOXP2 in three family members presenting with variable speech, language and neurodevelopmental phenotypes. The index individual showed delayed speech development with impaired speech production, reduced language comprehension, and additionally learning difficulties, microcephaly, and attention deficit. His younger sister had delayed speech development with impaired speech production and partially reduced language comprehension. Their mother had attended a school for children with speech and language deficiencies and presented with impaired articulation. The deletion had occurred de novo in the mother, includes 15 protein-coding genes and is located in close proximity to the 3' end of FOXP2. Though a novel locus at 7q31.2q31.31 associated with mild neurodevelopmental and more prominent speech and language impairment is possible, the close phenotypic overlap with FOXP2-associated speech and language disorder rather suggests a positional effect on FOXP2 expression and function.

Cerebellar Dysfunction, Cerebro-cerebellar Connectivity and Autism Spectrum Disorders

The cerebellum has long been conceptualized to control motor learning and motor coordination. However, increasing evidence suggests its roles in cognition and emotion behaviors. In particular, the cerebellum has been recognized as one of key brain regions affected in autism spectrum disorder (ASD). To better understand the contribution of the cerebellum in ASD pathogenesis, we here discuss recent behavioral, genetic, and molecular studies from the human and mouse models. In addition, we raise several questions that need to be investigated in future studies from the point view of cerebellar dysfunction, cerebro-cerebellar connectivity and ASD.

Developmental Connectivity and Molecular Phenotypes of Unique Cortical Projection Neurons that Express a Synapse-Associated Receptor Tyrosine Kinase

The complex circuitry and cell-type diversity of the cerebral cortex are required for its high-level functions. The mechanisms underlying the diversification of cortical neurons during prenatal development have received substantial attention, but understanding of neuronal heterogeneity is more limited during later periods of cortical circuit maturation. To address this knowledge gap, connectivity analysis and molecular phenotyping of cortical neuron subtypes that express the developing synapse-enriched MET receptor tyrosine kinase were performed. Experiments used a MetGFP transgenic mouse line, combined with coexpression analysis of class-specific molecular markers and retrograde connectivity mapping. The results reveal that MET is expressed by a minor subset of subcerebral and a larger number of intratelencephalic projection neurons. Remarkably, MET is excluded from most layer 6 corticothalamic neurons. These findings are particularly relevant for understanding the maturation of discrete cortical circuits, given converging evidence that MET influences dendritic elaboration and glutamatergic synapse maturation. The data suggest that classically defined cortical projection classes can be further subdivided based on molecular characteristics that likely influence synaptic maturation and circuit wiring. Additionally, given that MET is classified as a high confidence autism risk gene, the data suggest that projection neuron subpopulations may be differentially vulnerable to disorder-associated genetic variation.

Hominin-specific regulatory elements selectively emerged in oligodendrocytes and are disrupted in autism patients

Speciation is associated with substantial rewiring of the regulatory circuitry underlying the expression of genes. Determining which changes are relevant and underlie the emergence of the human brain or its unique susceptibility to neural disease has been challenging. Here we annotate changes to gene regulatory elements (GREs) at cell type resolution in the brains of multiple primate species spanning most of primate evolution. We identify a unique set of regulatory elements that emerged in hominins prior to the separation of humans and chimpanzees. We demonstrate that these hominin gains perferentially affect oligodendrocyte function postnatally and are preferentially affected in the brains of autism patients. This preference is also observed for human-specific GREs suggesting this system is under continued selective pressure. Our data provide a roadmap of regulatory rewiring across primate evolution providing insight into the genomic changes that underlie the emergence of the brain and its susceptibility to neural disease.

The understanding of the changes regulating gene expression relevant for the emergence of the human brain and its susceptibility to disease is limited. Here, the authors identified a set of regulatory elements that evolved in hominins affecting oligodendrocyte function, and link these to autism.

Gene Expression Correlates of the Cortical Network Underlying Sentence Processing

A pivotal question in modern neuroscience is which genes regulate brain circuits that underlie cognitive functions. However, the field is still in its infancy. Here we report an integrated investigation of the high-level language network (i.e., sentence-processing network) in the human cerebral cortex, combining regional gene expression profiles, task fMRI, large-scale neuroimaging meta-analysis, and resting-state functional network approaches. We revealed reliable gene expression-functional network correlations using three different network definition strategies, and identified a consensus set of genes related to connectivity within the sentence-processing network. The genes involved showed enrichment for neural development and actin-related functions, as well as association signals with autism, which can involve disrupted language functioning. Our findings help elucidate the molecular basis of the brain's infrastructure for language. The integrative approach described here will be useful for studying other complex cognitive traits.

Modeling Inflammation on Neurodevelopmental Disorders Using Pluripotent Stem Cells

Neurodevelopmental disorders (ND) are characterized by an impairment of the nervous system during its development, with a wide variety of phenotypes based on genetic or environmental cues. There are currently several disorders grouped under ND including intellectual disabilities (ID), attention-deficit hyperactivity disorder (ADHD), and autism spectrum disorders (ASD). Although NDs can have multiple culprits with varied diagnostics, several NDs present an inflammatory component. Taking advantage of induced pluripotent stem cells (iPSC), several disorders were modeled in a dish complementing in vivo data from rodent models or clinical data. Monogenic syndromes displaying ND are more feasible to be modeled using iPSCs also due to the ability to recruit patients and clinical data available. Some of these genetic disorders are Fragile X Syndrome (FXS), Rett Syndrome (RTT), and Down Syndrome (DS). Environmental NDs can be caused by maternal immune activation (MIA), such as the infection with Zika virus during pregnancy known to cause neural damage to the fetus. Our goal in this chapter is to review the advances of using stem cell research in NDs, focusing on the role of neuroinflammation on ASD and environmental NDs studies.

Longitudinal DNA methylation changes at MET may alter HGF/c-MET signalling in adolescents at risk for depression

Unrecognized depression during adolescence can result in adult suicidal behaviour. The aim of this study was to identify, replicate and characterize DNA methylation (DNAm) shifts in depression aetiology, using a longitudinal, multi-tissue (blood and brain) and multi-layered (genetics, epigenetics, transcriptomics) approach. We measured genome-wide blood DNAm data at baseline and one-year follow-up, and imputed genetic variants, in 59 healthy adolescents comprising the discovery cohort. Depression and suicidal symptoms were determined using the Development and Well-Being Assessment (DAWBA) depression band, Montgomery-Åsberg Depression Rating Scale-Self (MADRS-S) and SUicide Assessment Scale (SUAS). DNAm levels at follow-up were regressed against depression scores, adjusting for sex, age and the DNAm residuals at baseline. Higher methylation levels of 5% and 13% at cg24627299 within the MET gene were associated with higher depression scores (p_raw<1e-4) and susceptibility for suicidal symptoms (p_adj.<0.005). The nearby rs39748 was discovered to be a methylation and expression quantitative trait locus in blood cells. mRNA levels of hepatocyte growth factor (HGF) expression, known to strongly interact with MET, were inversely associated with methylation levels at cg24627299, in an independent cohort of 1180 CD14+ samples. In an open-access dataset of brain tissue, lower methylation at cg24627299 was found in 45 adults diagnosed with major depressive disorder compared with matched controls (p_adj.<0.05). Furthermore, lower MET expression was identified in the hippocampus of depressed individuals compared with controls in a fourth, independent cohort. Our findings reveal methylation changes at MET in the pathology of depression, possibly involved in downregulation of HGF/c-MET signalling the hippocampal region.

Dysfunction of the corticostriatal pathway in autism spectrum disorders

The corticostriatal pathway that carries sensory, motor, and limbic information to the striatum plays a critical role in motor control, action selection, and reward. Dysfunction of this pathway is associated with many neurological and psychiatric disorders. Corticostriatal synapses have unique features in their cortical origins and striatal targets. In this review, we first describe axonal growth and synaptogenesis in the corticostriatal pathway during development, and then summarize the current understanding of the molecular bases of synaptic transmission and plasticity at mature corticostriatal synapses. Genes associated with autism spectrum disorder (ASD) have been implicated in axonal growth abnormalities, imbalance of the synaptic excitation/inhibition ratio, and altered long-term synaptic plasticity in the corticostriatal pathway. Here, we review a number of ASD-associated high-confidence genes, including FMR1, KMT2A, GRIN2B, SCN2A, NLGN1, NLGN3, MET, CNTNAP2, FOXP2, TSHZ3, SHANK3, PTEN, CHD8, MECP2, DYRK1A, RELN, FOXP1, SYNGAP1, and NRXN, and discuss their relevance to proper corticostriatal function.

Control of cortical synapse development and plasticity by MET receptor tyrosine kinase, a genetic risk factor for autism

The key developmental milestone events of the human brain, such as neurogenesis, synapse formation, maturation, and plasticity, are determined by a myriad of molecular signaling events, including those mediated by a number of receptor tyrosine kinases (RTKs) and their cognate ligands. Aberrant or mistimed brain development and plasticity can lead to maladaptive changes, such as dysregulated synaptic connectivity and breakdown of circuit functions necessary for cognition and adaptive behaviors, which are hypothesized pathophysiologies of many neurodevelopmental and neuropsychiatric disorders. Here we review recent literature that supports autism spectrum disorder as a likely result of aberrant synapse development due to mistimed maturation and plasticity. We focus on MET RTK, a prominent genetic risk factor for autism, and discuss how a pleiotropic molecular signaling system engaged by MET exemplifies a genetic program that controls cortical circuit development and plasticity by modulating the anatomical and functional connectivity of cortical circuits, thus conferring genetic risk for neurodevelopmental disorders.

Association of genes with phenotype in autism spectrum disorder

Autism spectrum disorder (ASD) is a genetic heterogeneous neurodevelopmental disorder that is characterized by impairments in social interaction and speech development and is accompanied by stereotypical behaviors such as body rocking, hand flapping, spinning objects, sniffing and restricted behaviors. The considerable significance of the genetics associated with autism has led to the identification of many risk genes for ASD used for the probing of ASD specificity and shared cognitive features over the past few decades. Identification of ASD risk genes helps to unravel various genetic variants and signaling pathways which are involved in ASD. This review highlights the role of ASD risk genes in gene transcription and translation regulation processes, as well as neuronal activity modulation, synaptic plasticity, disrupted key biological signaling pathways, and the novel candidate genes that play a significant role in the pathophysiology of ASD. The current emphasis on autism spectrum disorders has generated new opportunities in the field of neuroscience, and further advancements in the identification of different biomarkers, risk genes, and genetic pathways can help in the early diagnosis and development of new clinical and pharmacological treatments for ASD.

Differences in Cognition and Behaviour in Multiplex and Simplex Autism: Does Prior Experience Raising a Child with Autism Matter?

Previous research has found multiplex (MPX) children have an advantage in cognition compared to simplex (SPX) children. However, MPX parent's previous experience with older diagnosed siblings has not been considered. We used a large database sample to investigate the MPX advantage and contribution of birth order. Children from the Autism Genetic Resource Exchange (AGRE) were stratified into first- (MPX¹, n  = 152) and second-affected MPX (MPX², n  = 143), SPX (n  = 111), and only-child SPX (SPX^OC, n  = 23) groups. Both MPX groups had higher cognitive scores compared to SPX groups, with no differences between MPX¹ and MPX² groups. No differences were found for autism symptoms or adaptive behaviour. These results suggest parent experience due to birth order is an unlikely contributor to the MPX cognitive advantage.

Beyond the brain: A multi-system inflammatory subtype of autism spectrum disorder

An immune-mediated subtype of autism spectrum disorder (ASD) has long been hypothesized. This article reviews evidence from family history studies of autoimmunity, immunogenetics, maternal immune activation, neuroinflammation, and systemic inflammation, which suggests immune dysfunction in ASD. Individuals with ASD have higher rates of co-morbid medical illness than the general population. Major medical co-morbidities associated with ASD are discussed by body system. Mechanisms by which FDA-approved and emerging treatments for ASD act upon the immune system are then reviewed. We conclude by proposing the hypothesis of an immune-mediated subtype of ASD which is characterized by systemic, multi-organ inflammation or immune dysregulation with shared mechanisms that drive both the behavioral and physical illnesses associated with ASD. Although gaps in evidence supporting this hypothesis remain, benefits of this conceptualization include framing future research questions that will help define a clinically meaningful subset of patients and focusing clinical interactions on early detection and treatment of high-risk medical illnesses as well as interfering behavioral signs and symptoms across the lifespan.

Placental and Fetal Effects of Onartuzumab, a Met/HGF Signaling Antagonist, When Administered to Pregnant Cynomolgus Monkeys

Onartuzumab is an engineered single arm, monovalent monoclonal antibody that targets the MET receptor and prevents hepatocyte growth factor (HGF) signaling. Knockout mice have clearly demonstrated that HGF/MET signaling is developmentally critical. A pre- and postnatal development study (enhanced design) was conducted in cynomolgus monkeys to evaluate the potential developmental consequences following onartuzumab administration. Control or onartuzumab, at loading/maintenance doses of 75/50 mg/kg (low) or 100/100 mg/kg (high), was administered intravenously once weekly to 12 confirmed pregnant female cynomolgus monkeys per group from gestation day (GD) 20 through GD 174. Onartuzumab administration resulted in decreased gestation length, decreased birth weight, and increased fetal and perinatal mortality. A GD147 C-section was conducted for a subset of Control and High Dose monkeys, and identified placental infarcts with hemorrhage in the chorionic plate, chorionic villus and/or decidual plate. These findings were limited to placentas from onartuzumab-treated animals. In addition, decreased cellularity of the hepatocytes with dilated hepatic sinusoids was inconsistently observed in the liver of a few fetal or infant monkeys that died in the perinatal period. Surviving offspring had some evidence of developmental delay compared with controls, but no overt teratogenicity. Overall, effects on the perinatal fetuses were consistent with those reported in knockout mice, but not as severe. Onartuzumab concentrations were low or below the level of detection in most offspring, with cord blood concentrations only 1%-2% of maternal levels on GD 147. Malperfusion secondary to onartuzumab-induced placental injury could explain the adverse pregnancy outcomes, fetal growth restriction and relatively low fetal exposures.

Gender Differences During Toddlerhood in Autism Spectrum Disorder: A Prospective Community-Based Longitudinal Follow-Up Study

Relatively few studies have examined gender differences in infants and toddlers, and most focus on clinically referred samples or high-risk infant cohorts. The current study aimed to examine gender differences in early autism manifestations and cognitive development in a community-ascertained sample. In total, 46 males and 21 females with ASD were seen at approximately 24 and 48 months of age. No significant gender differences were observed on overall cognitive ability, verbal skills, non-verbal skills, overall autism severity, or restricted repetitive behaviours. However, females were found to exhibit more social communication impairments than males. These findings may indicate that female toddlers with less severe or different, social communication impairments may be more likely to be missed during routine surveillance during toddlerhood.

Activation of neuronal genes via LINE-1 elements upon global DNA demethylation in human neural progenitors

DNA methylation contributes to the maintenance of genomic integrity in somatic cells, in part through the silencing of transposable elements. In this study, we use CRISPR-Cas9 technology to delete DNMT1, the DNA methyltransferase key for DNA methylation maintenance, in human neural progenitor cells (hNPCs). We observe that inactivation of DNMT1 in hNPCs results in viable, proliferating cells despite a global loss of DNA CpG-methylation. DNA demethylation leads to specific transcriptional activation and chromatin remodeling of evolutionarily young, hominoid-specific LINE-1 elements (L1s), while older L1s and other classes of transposable elements remain silent. The activated L1s act as alternative promoters for many protein-coding genes involved in neuronal functions, revealing a hominoid-specific L1-based transcriptional network controlled by DNA methylation that influences neuronal protein-coding genes. Our results provide mechanistic insight into the role of DNA methylation in silencing transposable elements in somatic human cells, as well as further implicating L1s in human brain development and disease.

DNA methylation plays an important role in silencing transposable elements. Here the authors find that loss of DNMT1 and DNA methylation leads to transcriptional activation and chromatin remodelling of evolutionarily young—hominoid-specific —LINE-1 elements which then act as alternative promoters for neuronal genes.