Project description:De novo pathogenic variants in CHD2 are one of the most common causes of the neurodevelopmental disorders (NDDs) that include refractory epilepsy, intellectual disability and autism spectrum disorders. In addition, somatic CHD2 variants, acquired later in life, are highly recurrent in certain types of leukemias. For both types of conditions, loss-of-CHD2 function is the likely pathogenic mechanism, and most variants are truncations. However, there is also evidence that missense variants can disrupt or abrogate CHD2 function, leading to loss-of-function, though they are harder to interpret, and many are classified as variants of uncertain significance (VUS). VUS are one of the biggest challenges for human geneticists, and represent the biggest class of variants returned on clinical genetic test reports, in part because we have a poor understanding of how missense variants impact protein function. Our research addresses these challenges by developing a multiplex assay of variant effect (MAVE) to discriminate between pathogenic and benign missense variants. We leveraged the fact that CHD2 is a chromatin remodeler and thus affects gene expression, protein abundance and the DNA methylation landscape to attempt to develop high-throughput assays. We aimed to establish a CHD2 episignature using DNA methylation arrays from multiple pathogenic and benign variant HAP1 cell lines. While episignatures have been well-established in blood samples from individuals with CHD2 pathogenic variants, we were unable to establish a CHD2-related DNA methylation signature in HAP1s, either due to the cell line, or because episignatures are established during embryogenesis (or both).
Project description:De novo pathogenic variants in CHD2 are one of the most common causes of the neurodevelopmental disorders (NDDs) that include refractory epilepsy, intellectual disability and autism spectrum disorders. In addition, somatic CHD2 variants, acquired later in life, are highly recurrent in certain types of leukemias. For both types of conditions, loss-of-CHD2 function is the likely pathogenic mechanism, and most variants are truncations. However, there is also evidence that missense variants can disrupt or abrogate CHD2 function, leading to loss-of-function, though they are harder to interpret, and many are classified as variants of uncertain significance (VUS). VUS are one of the biggest challenges for human geneticists, and represent the biggest class of variants returned on clinical genetic test reports, in part because we have a poor understanding of how missense variants impact protein function. Our research addresses these challenges by developing a multiplex assay of variant effect (MAVE) to discriminate between pathogenic and benign missense variants. We leveraged the fact that CHD2 is a chromatin remodeler and thus affects gene expression, protein abundance and the DNA methylation landscape to attempt to develop high-throughput assays. We aimed to establish a CHD2 transcriptomic signature using mRNA sequencing from multiple pathogenic and benign variant HAP1 cell lines. While CHD2 is a well-known chromatin remodeler and is expressed at appreciable levels in these cells, we were unable to establish a CHD2-related transcriptomic signature in HAP1s, possibly due to the cell line choice as most manifestations in patients are neurological.
Project description:Background: Mutations in the chromatin remodelling protein CHD2 have been strongly associated with multiple neurodevelopmental disorders. However the precise function of CHD2 through neuronal development remains largely uncharacterized. Methods: We have used our protocol for generating cortical interneurons from human embryonic stem cells to study the role of CHD2 in brain development Results: This work found that CHD2 binding is largely associated with open and active chromatin Conclusions: As CHD2 plays distinct roles in several aspects of interneuron development, pathogenic CHD2 mutations have high potential to disrupt one or more of these events, contributing to NDDs.
Project description:Chromodomain Helicase DNA-binding Domain 2 (CHD2), as a chromatin remodeling factor, was shown to be involved in the regulation of gene expression in embryonic development, neurodevelopment and myelopoiesis. However, its role in male germ cell development has not been elucidated. Here, we confirmed that CHD2 is abundantly expressed throughout the male germ cells with the highest expression in the spermatocytes of meiosis I. By constructing a heterozygous gene knockout mouse model of Chd2 (Chd2+/-), we demonstrated that CHD2 haploinsufficiency resulted in testicular developmental delay and increased rate of abnormal sperm in mice. DNA damage repair, synapsis and cell proliferation during spermatogenesis are impaired in Chd2+/- mice. In vitro experiments in C18-4 and GC-1 spg cells showed that CHD2 knockdown inhibits spermatogonial self-renewal. Mechanically, CHD2 maintained the enrichment of H3K4me3 in Ccnb1 and Ccnd2 promoter consequently promoting the transcription of Ccnb1 and Ccnd2. In addition, by interacting with cleavage stimulation factor CSTF3, CHD2 binds Oct4, Plzf mRNA and upregulates the expression of OCT4 and PLZF by improving mRNA stability. This is the first time to reveal the role and mechanism of CHD2 in maintaining spermatogonial self-renewal by promoting chromatin activity and mRNA stability in spermatogenesis.
Project description:Sequence-based genetic testing identifies causative variants in ~50% of individuals with developmental and epileptic encephalopathies (DEEs). Aberrant changes in DNA methylation are implicated in various neurodevelopmental disorders but remain unstudied in DEEs. We interrogate the diagnostic utility of genome-wide DNA methylation array analysis on peripheral blood samples from 582 individuals with genetically unsolved DEEs. We identify rare differentially methylated regions (DMRs) and explanatory episignatures to uncover causative and candidate genetic etiologies in 12 individuals. Using long-read sequencing, we identify DNA variants underlying rare DMRs, including one balanced translocation, three CG-rich repeat expansions, and four copy number variants. We also identify pathogenic variants associated with episignatures. Finally, we refine the CHD2 episignature using an 850K methylation array and bisulfite sequencing to investigate potential insights into CHD2 pathophysiology. Our study demonstrates the diagnostic yield of genome-wide DNA methylation analysis to identify causal and candidate variants as 2% (12/582) for unsolved DEE cases.
Project description:Background: Mutations in the chromatin remodeller CHD2 have been strongly associated with multiple neurodevelopmental disorders. However the precise function of CHD2 through neuronal development remains largely uncharacterized. Methods: We have used our protocol for generating cortical interneurons from human embryonic stem cells to study the role of CHD2 in cortical interneuron development, by comparing wild type hMGE and hcINs with a model with CHD2 haploinsufficency Results: This work found that CHD2 controls the expresson of genes with rolls in cell-cell interaction in neuronal precursors and directly influences the exprssion of genes necessary for the production of post-mitotic cortical interneurons Conclusions: As CHD2 plays distinct roles in several aspects of interneuron development, pathogenic CHD2 mutations have high potential to disrupt one or more of these events, contributing to neurodevelopmental disorders
Project description:Integrative analysis of colorectal cancer (CRC) whole genomes and matched transcriptomes revealed that somatic promoter mutations are associated with increased Chromodomain helicase DNA-binding protein 2 (CHD2) levels. In both primary and metastatic CRC patients, elevated CHD2 levels are associated with worse prognosis and overall survival. We find that CHD2 increases promoter-transcription start site-chromatin accessibility and transcriptional upregulation of multiple oncogenes. In vitro, elevated CHD2 promoted CRC cell proliferation, migration and growth. In orthotopic xenografts, CHD2 promoted higher tumor burden and abdominal metastases, most prominently to the liver. FTD/TPI is an FDA approved chemotherapy for advanced chemo-refractory CRC. In orthotopic CRC models, FTD/TPI was highly effective in reducing metastases and prolonging survival for CHD2 high expressing CRCs. Thus, high CHD2 expression may be a potential CRC chemopredictive biomarker for FTD/TPI. Overall, these results provide new insights into the role of non-coding mutations and CHD2 levels to promote CRC growth and metastasis.
Project description:We demonstrate that chromodomain helicase DNA-binding domain 2 (Chd2) is required to maintain the differentiation potential of mouse ESCs. Chd2-depleted ESCs showed suppressed expression of developmentally regulated genes upon differentiation and subsequent differentiation defects without affecting gene expression in the undifferentiated state. Furthermore, chromatin immunoprecipitation followed by sequencing revealed alterations in a proportion of nucleosomes of developmentally regulated genes in Chd2-depleted ESCs to enhance histone variant H3.3 enrichment, leading to elevated trimethylation of histone H3 lysine 27.Chd2 is essential to prevent suppressive chromatin formation in developmentally regulated genes and determines subsequent effects on developmental processes in the undifferentiated state.
Project description:Chromodomain Helicase DNA-binding Domain 2 (CHD2), as a chromatin remodeling factor, was shown to be involved in the regulation of gene expression in embryonic development, neurodevelopment and myelopoiesis. However, its role in male germ cell development has not been elucidated. Here, we confirmed that CHD2 is abundantly expressed throughout the male germ cells with the highest expression in the spermatocytes of meiosis I. By constructing a heterozygous gene knockout mouse model of Chd2 (Chd2+/-), we demonstrated that CHD2 haploinsufficiency resulted in testicular developmental delay and increased rate of abnormal sperm in mice. DNA damage repair, synapsis and cell proliferation during spermatogenesis are impaired in Chd2+/- mice. In vitro experiments in C18-4 and GC-1 spg cells showed that CHD2 knockdown inhibits spermatogonial self-renewal. Mechanically, CHD2 maintained the enrichment of H3K4me3 in Ccnb1 and Ccnd2 promoter consequently promoting the transcription of Ccnb1 and Ccnd2. In addition, by interacting with cleavage stimulation factor CSTF3, CHD2 binds Oct4, Plzf mRNA and upregulates the expression of OCT4 and PLZF by improving mRNA stability. This is the first time to reveal the role and mechanism of CHD2 in maintaining spermatogonial self-renewal by promoting chromatin activity and mRNA stability in spermatogenesis.
Project description:Considerable evidence suggests loss of function mutations in the chromatin remodeler, CHD2, contribute to a broad spectrum of human neurodevelopmental disorders. However, it is unknown how CHD2 mutations lead to impaired brain function. Here we report mice with heterozygous mutations in Chd2 exhibit deficits in neuron proliferation and a shift in neuronal excitability that included divergent changes in excitatory and inhibitory synaptic function. Further in vivo experiments show Chd2+/- mice displayed aberrant cortical rhythmogenesis and severe deficits in long-term memory, consistent with phenotypes observed in humans. We identified broad, age-dependent transcriptional changes in Chd2+/- mice, including alterations in neurogenesis, synaptic transmission and disease-related genes. Deficits in interneuron density and memory caused by Chd2+/- were reproduced by Chd2 mutation restricted to a subset of inhibitory neurons and corrected by interneuron transplantation. Our results provide initial insight into how Chd2 haploinsufficiency leads to aberrant cortical network function and impaired memory.