Deletion of the autism-related gene Chd8 alters activity-dependent transcriptional responses in mouse postmitotic neurons

Chromatin regulation of neuronal activity-dependent gene programs in circuit formation and plasticity

Neuronal activity-dependent transcription is crucial for the development and plasticity of neuronal circuits. At the chromatin level, the induction of neuronal activity-regulated genes is orchestrated through various mechanisms, including the deposition of histone modifications at regulatory elements, the binding of transcriptional activators and repressors, chromatin remodeling, and the control of 3D genome architecture. Here, we review our current understanding of how chromatin mechanisms regulate temporally distinct transcriptional waves following neuronal stimulation and allow neurons to mount cell type-specific and stimulus-specific transcriptional responses. We also highlight a specific epigenetic mechanism in developing neurons that maintains immediate early genes (IEGs) in an inactive though poised state, while simultaneously preparing them for rapid activation in response to sensory stimulation. We discuss how chromatin regulation mechanisms play a crucial role in controlling activity-regulated gene expression, enabling the implementation of precise gene expression programs during different stages of neural circuit development and plasticity.

Neural connections and molecular mechanisms underlying motor skill deficits in genetic models of autism spectrum disorders

Autism spectrum disorders (ASDs) comprise a broad category of neurodevelopmental disorders that include repetitive behaviors and difficulties in social interactions. Notably, individuals with ASDs exhibit significant impairments in motor skills even prior to the manifestation of other core symptoms. These skills are crucial for daily activities, such as communication, imitation, and exploration, and hold significant importance for individuals with ASDs. This review seeks to offer new insights into the understanding of motor skill impairments by delineating the pathological mechanisms underlying motor skill learning impairments associated with gene mutations in Fmr1, Chd8, Shank3, BTBR, 16p11.2, and Mecp2, predominantly drawing from well-characterized genetic mouse model studies and proposing potential targets for future therapeutic interventions. We further discuss the underlying pathogenic abnormalities associated with the development of specific brain regions within the cerebellum and cerebrum, as well as disruptions in the structure and function of critical neuronal connectivity pathways. Additional research utilizing epidemiological data, clinical observations, and animal research methodologies is warranted to enhance our understanding of the effect of motor skill learning on the growth, development, and social integration of children. Ultimately, our review suggests potential targets for future therapeutic interventions.

Genetic and epigenetic regulation of Treg cell fitness by autism-related chromatin remodeler CHD8

BACKGROUND

Chromatin remodeler chromodomain helicase DNA-binding protein 8 (CHD8) defines a subtype of autism that is associated with immune disorders. It remains unknown whether CHD8 plays a cell-intrinsic role in immune cells such as regulatory T cells (Tregs) that maintain immune tolerance through suppressing CD4+ and CD8+ effector T cells.

METHODS

Treg-specific conditional CHD8-deficient mice were generated by crossing Chd8Flox/Flox mice with Foxp3YFP-cre transgenic mice. Effects of CHD8 deficiency were investigated using hematoxylin and eosin (H&E) staining, flow cytometry, and multi-omics, including RNA-sequencing (RNA-seq), assay for transposase-accessible chromatin sequencing (ATAC-seq), and chromatin immunoprecipitation sequencing (CHIP-seq).

RESULTS

We found that Treg-specific CHD8 deletion led to early, fatal inflammation owing to increased CD4+ and CD8+ effector T cells. CHD8 deletion did not alter Treg homeostasis but increased their functional plasticity with elevated expression of effector T cell cytokines. CHIP-seq of Tregs uncovered that CHD8 binding genes were enriched in phosphatidylinositol-3 kinase (PI3K)-protein kinase B (Akt)-mammalian target of rapamycin (mTOR) signaling and several other pathways. RNA-seq and ATAC-seq revealed that CHD8 deletion upregulated a number of pathways, notably mammalian target of rapamycin complex 1 (mTORC1) signaling and its mediated glycolysis that have been reported to promote Treg plasticity. Integrating RNA-seq data with CHIP-seq and ATAC-seq data identified a number of CHD8 target genes whose expression depends on CHD8 direct binding-mediated chromatin remodeling.

CONCLUSIONS

Our findings suggest that CHD8 plays an important role in maintaining Treg fitness through genetic and epigenetic mechanisms to control autoimmunity, which may have important implications in immune changes in autism.

Oligogenic risk score for Gilles de la Tourette syndrome reveals a genetic continuum of tic disorders

Gilles de la Tourette syndrome (GTS) and other tic disorders (TDs) have a substantial genetic component with their heritability estimated at between 60 and 80%. Here we propose an oligogenic risk score of TDs using whole-genome sequencing (WGS) data from a group of Polish GTS patients, their families, and control samples (n = 278). In this study, we first reviewed the literature to obtain a preliminary list of 84 GTS/TD candidate genes. From this list, 10 final risk score genes were selected based on single-gene burden tests (SKAT p < 0.05) between unrelated GTS cases (n = 37) and synthetic control samples based on a database of local allele frequencies. These 10 genes were CHADL, DRD2, MAOA, PCDH10, HTR2A, SLITRK5, SORCS3, KCNQ5, CDH9, and CHD8. Variants in and in the vicinity (± 20 kbp) of the ten risk genes (n = 7654) with a median minor allele frequency in the non-Finnish European population of 0.02 were integrated into an additive classifier. This risk score was then applied to healthy and GTS-affected individuals from 23 families and 100 unrelated healthy samples from the Polish population (AUC-ROC = 0.62, p = 0.02). Application of the algorithm to a group of patients with other tic disorders revealed a continuous increase of the oligogenic score with healthy individuals with the lowest mean, then patients with other tic disorders, then GTS patients, and finally with severe GTS cases with the highest oligogenic score. We have further compared our WGS results with the summary statistics of the Psychiatric Genomics Consortium genome-wide association study (PGC GWAS) of TDs and found no signal overlap except for the CHADL gene locus. Polygenic risk scores from common variants of GTS GWAS show no difference between patient and control groups, except for the comparison between patients with non-GTS TDs and patients with severe GTS. Overall, we leveraged WGS data to construct a GTS/TD risk score based on variants that may cooperatively contribute to the aetiology of these disorders. This study provides evidence that typical and severe adult GTS as well as other tic disorders may exist on a single spectrum in terms of their genetic background.

The Deficiency of the ASD-Related Gene CHD8 Disrupts Behavioral Patterns and Inhibits Hippocampal Neurogenesis in Mice

Chromodomain helicase DNA-binding 8 (CHD8) is a gene that poses a high risk for autism spectrum disorder (ASD) and neurological development delay. Nevertheless, the impact of CHD8 haploinsufficiency on both hippocampus neurogenesis and behavior remains uncertain. Here, we performed behavioral assessments on male and female CHD8 heterozygous mice. The study discovered that both male and female CHD8 heterozygous mice displayed an impairment in preference for social novelty. Concurrently, CHD8 heterozygous mice exhibited anxiety-like behavior. However, its cognitive capacity for learning and memory is within the expected range. Furthermore, we discovered a reduction in the number of both immature and mature new neurons in mice with CHD8 heterozygous, resulting in an impeded neurogenesis process in the hippocampus. Taken together, our findings indicate that CHD8 plays a crucial role in the regulation of hippocampal neurogenesis, and further suggest that ASD-like behaviors observed in CHD8 heterozygous mice may be associated with disruptions in hippocampal neurogenesis.

Dynamic convergence of autism disorder risk genes across neurodevelopment

Over a hundred risk genes underlie risk for autism spectrum disorder (ASD) but the extent to which they converge on shared downstream targets to increase ASD risk is unknown. To test the hypothesis that cellular context impacts the nature of convergence, here we apply a pooled CRISPR approach to target 29 ASD loss-of-function genes in human induced pluripotent stem cell (hiPSC)-derived neural progenitor cells, glutamatergic neurons, and GABAergic neurons. Two distinct approaches (gene-level and network-level analyses) demonstrate that convergence is greatest in mature glutamatergic neurons. Convergent effects are dynamic, varying in strength, composition, and biological role between cell types, increasing with functional similarity of the ASD genes examined, and driven by cell-type-specific gene co-expression patterns. Stratification of ASD genes yield targeted drug predictions capable of reversing gene-specific convergent signatures in human cells and ASD-related behaviors in zebrafish. Altogether, convergent networks downstream of ASD risk genes represent novel points of individualized therapeutic intervention.

Neurodevelopmental functions of CHD8: new insights and questions

Heterozygous, de novo, loss-of-function variants of the CHD8 gene are associated with a high penetrance of autism and other neurodevelopmental phenotypes. Identifying the neurodevelopmental functions of high-confidence autism risk genes like CHD8 may improve our understanding of the neurodevelopmental mechanisms that underlie autism spectrum disorders. Over the last decade, a complex picture of pleiotropic CHD8 functions and mechanisms of action has emerged. Multiple brain and non-brain cell types and progenitors appear to be affected by CHD8 haploinsufficiency. Behavioural, cellular and synaptic phenotypes are dependent on the nature of the gene mutation and are modified by sex and genetic background. Here, I review some of the CHD8-interacting proteins and molecular mechanisms identified to date, as well as the impacts of CHD8 deficiency on cellular processes relevant to neurodevelopment. I endeavour to highlight some of the critical questions that still require careful and concerted attention over the next decade to bring us closer to the goal of understanding the salient mechanisms whereby CHD8 deficiency causes neurodevelopmental disorders.

A bibliometric analysis of autism spectrum disorder signaling pathways research in the past decade

Background

This study employs bibliometric methods to comprehensively understand the fundamental structure of research about Autism Spectrum Disorder (ASD) Signaling Pathways by examining key indicators such as nations, institutions, journals, authors, and keywords.

Methodology

We utilized the WoScc database to retrieve literature relevant to ASD Signaling Pathways published between 2013 and 2023. Through visual analysis and tools like CiteSpace and VosViewer, we explored nations, institutions, journals, authors, and keywords, thereby constructing relevant networks.

Results

26 The study encompasses 1,396 articles, revealing a consistent increase in publications. The United States, China, and Germany are leading nations in this literature. Regarding research institutions, the University of California system and Eric Klann have garnered significant attention due to their substantial contributions to the field of ASD Signaling Pathways. Most relevant research is published in the journal "Molecular Autism." Research interests are concentrated across various themes, including "elevating neuronal β-catenin levels," "Tunisian children," "Fmr1 knockout (KO) mice," "de novo mutations," "autistic children," "local translation," "propionic acid-induced mouse models," "neurosystems," "glucose metabolism," and "neuronal migration." Future research may emphasize exploring aspects such as gut microbiota, genes, stress, maternal immune activation, memory, and neurodevelopmental disorders of ASD.

Conclusion

This study, through bibliometric analysis of key indicators such as nations, institutions, journals, authors, and keywords, provides a comprehensive overview of the current state of research on ASD Signaling Pathways. These investigations predominantly focus on molecular mechanisms, animal model studies, population-based research, and the structure and function of neurosystems. Future research directions are also clearly proposed. First, in-depth research on the genes and neurodevelopmental disorders associated with ASD will continue to reveal the genetic basis and provide support for precise treatments. At the same time, attention to the gut microbiota will help explore its association with ASD, which may provide clues for new treatments. In addition, the relationship between stress and ASD will become the focus of research to understand better the emotional and behavioral characteristics of ASD patients in stressful situations. Maternal immune activation will also be further studied to explore how environmental factors influence the risk and development of ASD. Finally, a deeper understanding of the cognitive functions of patients with ASD, especially memory and learning, will help develop individualized treatment strategies to improve patients' quality of life. These directions will work together and are expected to provide a more comprehensive understanding of Signaling Pathways research in ASD and provide new ideas and opportunities for future intervention and treatment.