scholarly journals Dendritic Integration Dysfunction in Neurodevelopmental Disorders

2021 ◽  
pp. 1-21
Author(s):  
Andrew D. Nelson ◽  
Kevin J. Bender

Neurodevelopmental disorders (NDDs) that affect cognition, social interaction, and learning, including autism spectrum disorder (ASD) and intellectual disability (ID), have a strong genetic component. Our current understanding of risk genes highlights two main groups of dysfunction: those in genes that act as chromatin modifiers and those in genes that encode for proteins localized at or near synapses. Understanding how dysfunction in these genes contributes to phenotypes observed in ASD and ID remains a major question in neuroscience. In this review, we highlight emerging evidence suggesting that dysfunction in dendrites – regions of neurons that receive synaptic input – may be key to understanding features of neuronal processing affected in these disorders. Dendritic integration plays a fundamental role in sensory processing, cognition, and conscious perception, processes hypothesized to be impaired in NDDs. Many high-confidence ASD genes function within dendrites where they control synaptic integration and dendritic excitability. Further, increasing evidence demonstrates that several ASD/ID genes, including chromatin modifiers and transcription factors, regulate the expression or scaffolding of dendritic ion channels, receptors, and synaptic proteins. Therefore, we discuss how dysfunction of subsets of NDD-associated genes in dendrites leads to defects in dendritic integration and excitability and may be one core phenotype in ASD and ID.

2021 ◽  
Author(s):  
Angela G. Maggio ◽  
Henry T. Shu ◽  
Benjamin I. Laufer ◽  
Hyeyeon Hwang ◽  
Chongfeng Bi ◽  
...  

AbstractBackgroundAlthough autism spectrum disorder (ASD) is among the most heritable of neurodevelopmental disorders, the rapidly rising prevalence of ASD suggests that environmental factors may interact with genetic risk for ASD. Environmental factors may impact both gene expression and phenotypes in ASD through epigenetic modifications that, in turn, could lead to intergenerational effects influencing risk for ASDs. Endocrine disrupting compounds (EDCs), such as the long-lived organochlorines, are of particular interest with respect to risk for autism because of their ability to interfere with sex hormones that have been implicated in the regulation of RORA, a dysregulated gene in ASD that is a master regulator of many other ASD risk genes.ObjectivesThe specific aims of this study are to: 1) investigate whether high versus low exposures to the persistent organochlorine 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) are associated with differentially methylated regions (DMRs) in sperm from a Faroese cohort whose natural diet of pilot whale meat and blubber exposes them to higher than average levels of organic pollutants; 2) determine if genes associated with DDE DMRs are enriched for ASD risk genes; 3) identify pathways and functions over-represented among genes associated with DMRs.MethodsWhole genome bisulfite sequencing (WGBS) was used to identify genome-wide DMRs in sperm from individuals divided by high and low exposure levels. Gene ontology and pathway analyses were used to determine enrichment in functional relationships to ASD.ResultsGenes in DMRs not only could discriminate between high and low exposures to DDE, but also were enriched in autism risk genes. Gene ontology and pathway analyses of these genes show significant enrichment for neurodevelopmental processes frequently impacted by ASD.ConclusionResults of this study show that elevated exposure to certain organochlorines is associated with genome-wide DNA methylation patterns in sperm affecting genes involved in neurological functions and developmental disorders, including ASD.


2022 ◽  
Author(s):  
Samuel Thudium ◽  
Katherine C Palozola ◽  
Eloise L'Her ◽  
Erica Korb

Epigenetic regulation plays a critical role in many neurodevelopmental disorders, including Autism Spectrum Disorder (ASD). In particular, many such disorders are the result of mutations in genes that encode chromatin modifying proteins. However, while these disorders share many features, it is unclear whether they also share gene expression disruptions resulting from the aberrant regulation of chromatin. We examined 5 chromatin modifiers that are all linked to ASD despite their different roles in regulating chromatin. Specifically, we depleted Ash1L, Chd8, Crebbp, Ehmt1, and Nsd1 in parallel in a highly controlled neuronal culture system. We then identified sets of shared genes, or transcriptional signatures, that are differentially expressed following loss of multiple ASD-linked chromatin modifiers. We examined the functions of genes within the transcriptional signatures and found an enrichment in many neurotransmitter transport genes and activity-dependent genes. In addition, these genes are enriched for specific chromatin features such as bivalent domains that allow for highly dynamic regulation of gene expression. The downregulated transcriptional signature is also observed within multiple mouse models of neurodevelopmental disorders that result in ASD, but not those only associated with intellectual disability. Finally, the downregulated transcriptional signature can distinguish between neurons generated from iPSCs derived from healthy donors and idiopathic ASD patients through RNA-deconvolution, demonstrating that this gene set is relevant to the human disorder. This work identifies a transcriptional signature that is found within many neurodevelopmental syndromes, helping to elucidate the link between epigenetic regulation and the underlying cellular mechanisms that result in ASD.


2020 ◽  
Author(s):  
Elliott Rees ◽  
Hugo Creeth ◽  
Hai-Gwo Hwu ◽  
Wei Chen ◽  
Ming Tsuang ◽  
...  

Abstract Genes enriched for rare disruptive coding variants in schizophrenia overlap those in which disruptive mutations are associated with neurodevelopmental disorders (NDDs), particularly autism spectrum disorders and intellectual disability. However, it is unclear whether this implicates the same specific variants, or even variants with the same functional effects on shared risk genes. Here, we show that de novo mutations in schizophrenia are generally of the same functional category as those that confer risk for NDDs, and that the specific de novo mutations in NDDs are enriched in schizophrenia. These findings indicate that, in part, NDDs and schizophrenia have shared molecular aetiology, and therefore likely overlapping pathophysiology. We also observe pleiotropic effects for variants known to be pathogenic for several syndromic developmental disorders, suggesting that schizophrenia should be included among the phenotypes associated with these mutations. Collectively, our findings support the hypothesis that at least some forms of schizophrenia lie within a continuum of neurodevelopmental disorders.


2018 ◽  
Author(s):  
Daniel M. Fass ◽  
Michael C. Lewis ◽  
Rushdy Ahmad ◽  
Matthew J. Szucs ◽  
Qiangge Zhang ◽  
...  

AbstractDespite tremendous effort, the molecular and cellular basis of cognitive deficits in schizophrenia remain poorly understood. Recent progress in elucidating the genetic architecture of schizophrenia has highlighted the association of multiple loci and rare variants that may impact susceptibility. One key example, given their potential etiopathogenic and therapeutic relevance, is a set of genes that encode proteins that regulate excitatory glutamatergic synapses in brain. A critical next step is to delineate specifically how such genetic variation impacts synaptic plasticity and to determine if and how the encoded proteins interact biochemically with one another to control cognitive function in a convergent manner. Towards this goal, here we study the roles of GPCR-kinase interacting protein 1 (GIT1), a synaptic scaffolding and signaling protein with damaging coding variants found in schizophrenia patients, as well as copy number variants found in patients with neurodevelopmental disorders. We generated conditional neural-selective GIT1 knockout mice and find that these mice have deficits in fear conditioning learning and spatial memory. Using global quantitative phospho-proteomics, we revealed that GIT1 deletion in brain perturbs specific networks of GIT1-interacting synaptic proteins. Importantly, several schizophrenia and neurodevelopmental disorder risk genes are present within these networks. We propose that GIT1 regulates the phosphorylation of a network of synaptic proteins and other critical regulators of neuroplasticity, and that perturbation of these networks may contribute to cognitive deficits observed in schizophrenia and neurodevelopmental disorders.


2020 ◽  
Author(s):  
Elliott Rees ◽  
Hugo D. J. Creeth ◽  
Hai-Gwo Hwu ◽  
Wei J. Chen ◽  
Ming Tsuang ◽  
...  

AbstractGenes enriched for rare disruptive coding variants in schizophrenia overlap those in which disruptive mutations are associated with neurodevelopmental disorders (NDDs), particularly autism spectrum disorders and intellectual disability. However, it is unclear whether this implicates the same specific variants, or even variants with the same functional effects on shared risk genes. Here, we show that de novo mutations in schizophrenia are generally of the same functional category as those that confer risk for NDDs, and that the specific de novo mutations in NDDs are enriched in schizophrenia. These findings indicate that, in part, NDDs and schizophrenia have shared molecular aetiology, and therefore likely overlapping pathophysiology. We also observe pleiotropic effects for variants known to be pathogenic for several syndromic developmental disorders, suggesting that schizophrenia should be included among the phenotypes associated with these mutations. Collectively, our findings support the hypothesis that at least some forms of schizophrenia lie within a continuum of neurodevelopmental disorders.


2016 ◽  
Author(s):  
Tarjinder Singh ◽  
James T. R. Walters ◽  
Mandy Johnstone ◽  
David Curtis ◽  
Jaana Suvisaari ◽  
...  

AbstractBy meta-analyzing rare coding variants in whole-exome sequences of 4,264 schizophrenia cases and 9,343 controls, de novo mutations in 1,077 trios, and array-based copy number variant calls from 6,882 cases and 11,255 controls, we show that individuals with schizophrenia carry a significant burden of rare damaging variants in a subset of 3,230 “highly constrained” genes previously identified as having near-complete depletion of protein truncating variants. Furthermore, rare variant enrichment analyses demonstrate that this burden is concentrated in known autism spectrum disorder risk genes, genes diagnostic of severe developmental disorders, and the autism-implicated sets of promoter targets of CHD8, and mRNA targets of FMRP. We further show that schizophrenia patients with intellectual disability have a greater enrichment of rare damaging variants in highly constrained genes and developmental disorder genes, but that a weaker but significant enrichment exists throughout the larger schizophrenia population. Combined, our results demonstrate that schizophrenia risk loci of large effect across a range of variant types implicate a common set of genes shared with broader neurodevelopmental disorders, suggesting a path forward in identifying additional risk genes in psychiatric disorders and further supporting a neurodevelopmental etiology to the pathogenesis of schizophrenia.


2021 ◽  
Author(s):  
Greta Pintacuda ◽  
Yu-Han H Hsu ◽  
Kalliopi Tsafou ◽  
Ka Wan Li ◽  
Jacqueline M Martin ◽  
...  

Sequencing studies of autism spectrum disorders (ASDs) have identified numerous risk genes with enriched expression in the human brain, but it is still unclear how these genes converge into cell type-specific networks and how their encoded proteins mechanistically contribute to ASDs. To address this question, we performed brain cell type-specific interaction proteomics to build a protein-protein interaction network for 13 ASD risk genes in human excitatory neurons derived from iPS cells. The network contains many (>90%) reproducible interactions not reported in the literature and is enriched for transcriptionally perturbed genes observed in layer 2/3 cortical neurons of ASD patients, indicating that it can be explored for ASD-relevant biological discovery. We leveraged the network dataset to show that the brain-specific isoform of ANK2 is important for its interactions with synaptic proteins and characterized a PTEN-AKAP8L interaction that influences neuronal growth through the mTOR pathway. The IGF2BP1-3 complex emerges as a point of convergence in the network, and we showed that this complex is involved in a transcriptional circuit concentrating both common and rare variant risk of ASDs. Finally, we found the network itself enriched for ASD rare variant risk, indicating that it can complement genetic datasets for prioritizing additional risk genes. Our findings establish brain cell type-specific interactomes as an organizing framework to facilitate interpretation of genetic and transcriptomic data in ASDs and illustrate how both individual and convergent interactions lead to biological insights into the disease.


2020 ◽  
Author(s):  
Ilayda Beyreli ◽  
Oguzhan Karakahya ◽  
A. Ercument Cicek

AbstractAutism Spectrum Disorder (ASD) and Intellectual Disability (ID) are comorbid neurodevelopmental disorders with complex genetic architectures. Despite large-scale sequencing studies only a fraction of the risk genes were identified for both. Here, we present a novel network-based gene risk prioritization algorithm named DeepND that performs cross-disorder analysis to improve prediction power by exploiting the comorbidity of ASD and ID via multitask learning. Our model leverages information from gene co-expression networks that model human brain development using graph convolutional neural networks and learns which spatio-temporal neurovelopmental windows are important for disorder etiologies. We show that our approach substantially improves the state-of-the-art prediction power in both single-disorder and cross-disorder settings. DeepND identifies mediodorsal thalamus and cerebral cortex brain region and infancy to childhood period as the highest neurodevelopmental risk window for both ASD and ID. We observe that both disorders are enriched in transcription regulators. Despite tight regulatory links in between ASD risk genes, such is lacking across ASD and ID risk genes or within ID risk genes. Finally, we investigate frequent ASD and ID associated copy number variation regions and confident false findings to suggest several novel susceptibility gene candidates. DeepND can be generalized to analyze any combinations of comorbid disorders and is released at http://github.com/ciceklab/deepnd.


2020 ◽  
Author(s):  
Laurie John Hannigan ◽  
Ragna Bugge Askeland ◽  
Helga Ask ◽  
Martin Tesli ◽  
Elizabeth Corfield ◽  
...  

BackgroundEarly developmental milestones, such as the age at first walking or talking, are associated with later diagnoses of neurodevelopmental disorders, but the relationship to genetic risk for neurodevelopmental disorders are unknown. Here, we investigate associations between genetic liability to autism spectrum disorder (autism), attention deficit hyperactivity disorder (ADHD), and schizophrenia and attainment of early-life language and motor development milestones.MethodsWe use data from a genotyped sub-set (N = 15 205) of children in the Norwegian Mother, Father and Child Cohort Study (MoBa). In this sample, we calculate polygenic scores for autism; ADHD and schizophrenia and predict maternal reports of children’s age at first walking and talking, motor delays at 18 months, language delays at 3 years, and a generalized measure of concerns about development. We use linear and probit regression models in a multi-group framework to test for sex differences.ResultsADHD polygenic scores predicted earlier walking age in both males and females (β=-0.037, pFDR=0.001), and earlier first use of sentences (β=-0.087, pFDR=0.032) but delayed language development at 3 years in females only (β=0.194, pFDR=0.001). Additionally, we found evidence that autism polygenic scores were associated with later walking (β=0.027, pFDR=0.024) and motor delays at 18 months (β = 0.065, pFDR=0.028). Schizophrenia polygenic scores were associated with a measure of general concerns about development at 3 years in females only (β=0.132, pFDR=0.024).ConclusionsGenetic liabilities for neurodevelopmental disorders show some specific associations with measures of early motor and language development in the general population, including the age at which children first walk and talk. Associations are generally small and occasionally in unexpected directions. Sex differences are evident in some instances, but clear patterns across different polygenic scores and outcomes are hard to discern. These findings suggest that genetic susceptibility for neurodevelopmental disorders is manifested in the timing of developmental milestones in infancy.


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