CHD4 and SMYD1 repress common transcriptional programs in the developing heart.

Regulation of chromatin states is essential for proper temporal and spatial gene expression. Chromatin states are modulated by remodeling complexes composed of components that have enzymatic activities. CHD4 is the catalytic core of the nucleosome remodeling and deacetylase (NuRD) complex, which represses gene transcription. However, it remains to be determined how CHD4, a ubiquitous enzyme that remodels chromatin structure, functions in cardiomyocytes to maintain heart development. In particular, whether other proteins besides the NuRD components interact with CHD4 in the heart is controversial. Using quantitative proteomics, we identified that CHD4 interacts with SMYD1, a striated muscle-restricted histone methyltransferase that is essential for cardiomyocyte differentiation and cardiac morphogenesis. Comprehensive transcriptomic and chromatin accessibility studies of Smyd1 and Chd4 null embryonic mouse hearts revealed that SMYD1 and CHD4 repress a group of common genes and pathways involved in glycolysis, response to hypoxia, and angiogenesis. Our study reveals a mechanism by which CHD4 functions during heart development, and a previously uncharacterized mechanism regarding how SMYD1 represses cardiac transcription in the developing heart.

lncRNA LINC00941 modulates MTA2/NuRD occupancy to suppress premature human epidermal differentiation.

Numerous long non-coding RNAs (lncRNAs) were shown to have a functional impact on cellular processes such as human epidermal homeostasis. However, the mechanism of action for many lncRNAs remains unclear to date. Here, we report that lncRNA LINC00941 regulates keratinocyte differentiation on an epigenetic level through association with the NuRD complex, one of the major chromatin remodelers in cells. We find that LINC00941 interacts with NuRD-associated MTA2 and CHD4 in human primary keratinocytes. LINC00941 perturbation changes MTA2/NuRD occupancy at bivalent chromatin domains in close proximity to transcriptional regulator genes, including the EGR3 gene coding for a transcription factor regulating epidermal differentiation. Notably, LINC00941 depletion resulted in reduced NuRD occupancy at the EGR3 gene locus, increased EGR3 expression in human primary keratinocytes, and increased abundance of EGR3-regulated epidermal differentiation genes in cells and human organotypic epidermal tissues. Our results therefore indicate a role of LINC00941/NuRD in repressing EGR3 expression in non-differentiated keratinocytes, consequentially preventing premature differentiation of human epidermal tissues.

Identification and characterization of CHD4-associated eRNA as a novel modulator of fetal hemoglobin levels in ß-thalassemia.

Fetal-to-adult hemoglobin switching is controlled by programmed silencing of γ-globin while the re-activation of fetal hemoglobin (HbF) is an effective strategy for ameliorating the clinical severity of ß-thalassemia and sickle cell disease. The identification of enhancer RNAs (eRNAs) related to the fetal (α2γ2) to adult hemoglobin (α2ß2) switching remains incomplete. In this study, the transcriptomes of GYPA+ cells from six ß-thalassemia patients with extreme HbF levels were sequenced to identify differences in patterns of noncoding RNA expression. It is interesting that an enhancer upstream of CHD4, an HbF-related core subunit of the NuRD complex, was differentially transcribed. We found a significantly positive correlation of eRNA-CHD4 enhancer-gene interaction using the public database of FANTOM5. Specifically, the eRNA-CHD4 expression was found to be significantly higher in both CD34+ HSPCs and HUDEP-2 than those in K562 cells which commonly expressed high level of HbF, suggesting a correlation between eRNA and HbF expression. Furthermore, prediction of transcription binding sites of cis-eQTLs and the CHD4 genomic region revealed a putative interaction site between rs73264846 and ZNF410, a known transcription factor regulating HbF expression. Moreover, in-vitro validation showed that the inhibition of eRNA could reduce the expression of HBG expression in HUDEP-2 cells. Taken together, the findings of this study demonstrate that a distal enhancer contributes to stage-specific silencing of γ-globin genes through direct modulation of CHD4 expression and provide insights into the epigenetic mechanisms of NuRD-mediated hemoglobin switching.

Genomic transcription factor binding site selection is edited by the chromatin remodeling factor CHD4.

Biologically precise enhancer licensing by lineage-determining transcription factors enables activation of transcripts appropriate to biological demand and prevents deleterious gene activation. This essential process is challenged by the millions of matches to most transcription factor binding motifs present in many eukaryotic genomes, leading to questions about how transcription factors achieve the exquisite specificity required. The importance of chromatin remodeling factors to enhancer activation is highlighted by their frequent mutation in developmental disorders and in cancer. Here, we determine the roles of CHD4 in enhancer licensing and maintenance in breast cancer cells and during cellular reprogramming. In unchallenged basal breast cancer cells, CHD4 modulates chromatin accessibility. Its depletion leads to redistribution of transcription factors to previously unoccupied sites. During cellular reprogramming induced by the pioneer factor GATA3, CHD4 activity is necessary to prevent inappropriate chromatin opening. Mechanistically, CHD4 promotes nucleosome positioning over GATA3 binding motifs to compete with transcription factor-DNA interaction. We propose that CHD4 acts as a chromatin proof-reading enzyme that prevents unnecessary gene expression by editing chromatin binding activities of transcription factors.

The Chromatin Remodeler CHD4 Sustains Ewing Sarcoma Cell Survival by Controlling Global Chromatin Architecture.

Ewing sarcoma is an aggressive cancer with a defective response to DNA damage leading to an enhanced sensitivity to genotoxic agents. Mechanistically, Ewing sarcoma is driven by the fusion transcription factor EWS-FLI1, which reprograms the tumor cell epigenome. The nucleosome remodeling and deacetylase (NuRD) complex is an important regulator of chromatin function, controlling both gene expression and DNA damage repair, and has been associated with EWS-FLI1 activity. Here, a NuRD-focused CRISPR/Cas9 inactivation screen identified the helicase CHD4 as essential for Ewing sarcoma cell proliferation. CHD4 silencing induced tumor cell death by apoptosis and abolished colony formation. Although CHD4 and NuRD colocalized with EWS-FLI1 at enhancers and super-enhancers, CHD4 promoted Ewing sarcoma cell survival not by modulating EWS-FLI1 activity and its oncogenic gene expression program but by regulating chromatin structure. CHD4 depletion led to a global increase in DNA accessibility and induction of spontaneous DNA damage, resulting in an increased susceptibility to DNA-damaging agents. CHD4 loss delayed tumor growth in vivo, increased overall survival, and combination with PARP inhibition by olaparib treatment further suppressed tumor growth. Collectively, these findings highlight the NuRD subunit CHD4 as a therapeutic target in Ewing sarcoma that can potentiate the antitumor activity of genotoxic agents. SIGNIFICANCE: CRISPR/Cas9 screening in Ewing sarcoma identifies a dependency on CHD4, which is crucial for the maintenance of chromatin architecture to suppress DNA damage and a promising therapeutic target for DNA damage repair-deficient malignancies.

Inhibition of the chromatin remodeling factor NURF rescued sterility by a clinic variant of NuRD.

The nucleosome remodeling and deacetylase (NuRD) complex is essential for gene expression and cell fate determination, and missense mutations of NuRD caused neurodevelopmental diseases. However, the molecular pathogenesis of clinic NuRD variants is unknown. Here, we introduced a clinic CHD3 (L915F) variant into Caenorhabditis elegans homologue LET-418, impairing germline and vulva development and ultimately causing animal sterility. Our ATAC-seq and RNA-seq analyses revealed that this variant generated an abnormal open chromatin structure and disrupted the expression of developmental genes. Through genetic suppressor screens, we uncovered that intragenic mutations, likely renovating NuRD activity, restored animal viability. We also found that intergenic mutations in nucleosome remodeling factor NURF that counteracts NuRD rescued abnormal chromatin structure, gene expression, and animal sterility. We propose that two antagonistic chromatin-remodeling factors coordinate to establish the proper chromatin status and transcriptome and that inhibiting NURF may provide insights for treatment of NuRD mutation-related diseases.

A severe neurocognitive phenotype caused by biallelic CHD3 variants in two siblings.

CHD3 heterozygous variants are associated with Snijders Blok-Campeau syndrome (SBCS) which consists of intellectual disability (ID), macrocephaly, and dysmorphic facies. Most reported variants are missense or loss of function clustered within the ATPase/helicase domain of the protein. We report a severe neurocognitive phenotype caused by biallelic CHD3 variants in two siblings, each inherited from a mildly affected parent. Male and female siblings were referred to the Genetics Clinic due to severe ID and profound dysmorphism. The parents are first cousins of Iranian descent with borderline intellectual abilities. Exome sequencing was performed for the affected female and her parents. A single homozygous candidate variant in the CHD3 gene was detected in the proband: c.5384_5389dup. p.Arg1796_Phe1797insTrpArg, resulting in an in-frame insertion of 2 amino acids located outside the ATPase/helicase domain at the C-terminal region of CHD3-encoding residues. This variant is classified as likely pathogenic according to ACMG guidelines. The variant was detected in a heterozygous state in each parent. Both affected siblings were homozygous, while their unaffected brother did not carry the variant. Biallelic CHD3 variants cause a severe neurodevelopmental syndrome that is distinguishable from SBCS. We assume that the variant type (in-frame insertion) and location may enable CHD3 biallelic variants.

The Nucleosome Remodelling and Deacetylation complex coordinates the transcriptional response to lineage commitment in pluripotent cells.

As cells exit the pluripotent state and begin to commit to a specific lineage they must activate genes appropriate for that lineage while silencing genes associated with pluripotency and preventing activation of lineage-inappropriate genes. The Nucleosome Remodelling and Deacetylation (NuRD) complex is essential for pluripotent cells to successfully undergo lineage commitment. NuRD controls nucleosome density at regulatory sequences to facilitate transcriptional responses, and also has been shown to prevent unscheduled transcription (transcriptional noise) in undifferentiated pluripotent cells. How these activities combine to ensure cells engage a gene expression program suitable for successful lineage commitment has not been determined. Here, we show that NuRD is not required to silence all genes. Rather, it restricts expression of genes primed for activation upon exit from the pluripotent state, but maintains them in a transcriptionally permissive state in self-renewing conditions, which facilitates their subsequent activation upon exit from naïve pluripotency. We further show that NuRD coordinates gene expression changes, which acts to maintain a barrier between different stable states. Thus NuRD-mediated chromatin remodelling serves multiple functions, including reducing transcriptional noise, priming genes for activation and coordinating the transcriptional response to facilitate lineage commitment.

ß1 integrin signaling governs necroptosis via the chromatin-remodeling factor CHD4.

Fibrosis, characterized by sustained activation of myofibroblasts and excessive extracellular matrix (ECM) deposition, is known to be associated with chronic inflammation. Receptor-interacting protein kinase 3 (RIPK3), the central kinase of necroptosis signaling, is upregulated in fibrosis and contributes to tumor necrosis factor (TNF)-mediated inflammation. In bile-duct-ligation-induced liver fibrosis, we found that myofibroblasts are the major cell type expressing RIPK3. Genetic ablation of ß1 integrin, the major profibrotic ECM receptor in fibroblasts, not only abolished ECM fibrillogenesis but also blunted RIPK3 expression via a mechanism mediated by the chromatin-remodeling factor chromodomain helicase DNA-binding protein 4 (CHD4). While the function of CHD4 has been conventionally linked to the nucleosome-remodeling deacetylase (NuRD) and CHD4-ADNP-HP1(ChAHP) complexes, we found that CHD4 potently repressed a set of genes, including Ripk3, with high locus specificity but independent of either the NuRD or the ChAHP complex. Thus, our data uncover that ß1 integrin intrinsically links fibrotic signaling to RIPK3-driven inflammation via a novel mode of action of CHD4.

Snijders Blok-Campeau Syndrome: Description of 20 Additional Individuals with Variants in CHD3 and Literature Review.

Snijders Blok-Campeau syndrome (SNIBCPS, OMIM# 618205) is an extremely infrequent disease with only approximately 60 cases reported so far. SNIBCPS belongs to the group of neurodevelopmental disorders (NDDs). Clinical features of patients with SNIBCPS include global developmental delay, intellectual disability, speech and language difficulties and behavioral disorders like autism spectrum disorder. In addition, patients with SNIBCPS exhibit typical dysmorphic features including macrocephaly, hypertelorism, sparse eyebrows, broad forehead, prominent nose and pointed chin. The severity of the neurological effects as well as the presence of other features is variable among subjects. SNIBCPS is caused likely by pathogenic and pathogenic variants in CHD3 (Chromodomain Helicase DNA Binding Protein 3), which seems to be involved in chromatin remodeling by deacetylating histones. Here, we report 20 additional patients with clinical features compatible with SNIBCPS from 17 unrelated families with confirmed likely pathogenic/pathogenic variants in CHD3. Patients were analyzed by whole exome sequencing and segregation studies were performed by Sanger sequencing. Patients in this study showed different pathogenic variants affecting several functional domains of the protein. Additionally, none of the variants described here were reported in control population databases, and most computational predictors suggest that they are deleterious. The most common clinical features of the whole cohort of patients are global developmental delay (98%) and speech disorder/delay (92%). Other frequent features (51-74%) include intellectual disability, hypotonia, hypertelorism, abnormality of vision, macrocephaly and prominent forehead, among others. This study expands the number of individuals with confirmed SNIBCPS due to pathogenic or likely pathogenic variants in CHD3. Furthermore, we add evidence of the importance of the application of massive parallel sequencing for NDD patients for whom the clinical diagnosis might be challenging and where deep phenotyping is extremely useful to accurately manage and follow up the patients.

BCL11B and the NuRD complex cooperatively guard T-cell fate and inhibit OPA1-mediated mitochondrial fusion in T cells.

The nucleosome remodeling and histone deacetylase (NuRD) complex physically associates with BCL11B to regulate murine T-cell development. However, the function of NuRD complex in mature T cells remains unclear. Here, we characterize the fate and metabolism of human T cells in which key subunits of the NuRD complex or BCL11B are ablated. BCL11B and the NuRD complex bind to each other and repress natural killer (NK)-cell fate in T cells. In addition, T cells upregulate the NK cell-associated receptors and transcription factors, lyse NK-cell targets, and are reprogrammed into NK-like cells (ITNKs) upon deletion of MTA2, MBD2, CHD4, or BCL11B. ITNKs increase OPA1 expression and exhibit characteristically elongated mitochondria with augmented oxidative phosphorylation (OXPHOS) activity. OPA1-mediated elevated OXPHOS enhances cellular acetyl-CoA levels, thereby promoting the reprogramming efficiency and antitumor effects of ITNKs via regulating H3K27 acetylation at specific targets. In conclusion, our findings demonstrate that the NuRD complex and BCL11B cooperatively maintain T-cell fate directly by repressing NK cell-associated transcription and indirectly through a metabolic-epigenetic axis, providing strategies to improve the reprogramming efficiency and antitumor effects of ITNKs.

Analysis of the complex between MBD2 and the histone deacetylase core of NuRD reveals key interactions critical for gene silencing.

The nucleosome remodeling and deacetylase (NuRD) complex modifies nucleosome positioning and chromatin compaction to regulate gene expression. The methyl-CpG-binding domain proteins 2 and 3 (MBD2 and MBD3) play a critical role in complex formation; however, the molecular details of how they interact with other NuRD components have yet to be fully elucidated. We previously showed that an intrinsically disordered region (IDR) of MBD2 is necessary and sufficient to bind to the histone deacetylase core of NuRD. Building on that work, we have measured the inherent structural propensity of the MBD2-IDR using solvent and site-specific paramagnetic relaxation enhancement measurements. We then used the AlphaFold2 machine learning software to generate a model of the complex between MBD2 and the histone deacetylase core of NuRD. This model is remarkably consistent with our previous studies, including the current paramagnetic relaxation enhancement data. The latter suggests that the free MBD2-IDR samples conformations similar to the bound structure. We tested this model of the complex extensively by mutating key contact residues and measuring binding using an intracellular bioluminescent resonance energy transfer assay. Furthermore, we identified protein contacts that, when mutated, disrupted gene silencing by NuRD in a cell model of fetal hemoglobin regulation. Hence, this work provides insights into the formation of NuRD and highlights critical binding pockets that may be targeted to block gene silencing for therapy. Importantly, we show that AlphaFold2 can generate a credible model of a large complex that involves an IDR that folds upon binding.

Collateral lethality between HDAC1 and HDAC2 exploits cancer-specific NuRD complex vulnerabilities.

Transcriptional co-regulators have been widely pursued as targets for disrupting oncogenic gene regulatory programs. However, many proteins in this target class are universally essential for cell survival, which limits their therapeutic window. Here we unveil a genetic interaction between histone deacetylase 1 (HDAC1) and HDAC2, wherein each paralog is synthetically lethal with hemizygous deletion of the other. This collateral synthetic lethality is caused by recurrent chromosomal deletions that occur in diverse solid and hematological malignancies, including neuroblastoma and multiple myeloma. Using genetic disruption or dTAG-mediated degradation, we show that targeting HDAC2 suppresses the growth of HDAC1-deficient neuroblastoma in vitro and in vivo. Mechanistically, we find that targeted degradation of HDAC2 in these cells prompts the degradation of several members of the nucleosome remodeling and deacetylase (NuRD) complex, leading to diminished chromatin accessibility at HDAC2-NuRD-bound sites of the genome and impaired control of enhancer-associated transcription. Furthermore, we reveal that several of the degraded NuRD complex subunits are dependencies in neuroblastoma and multiple myeloma, providing motivation to develop paralog-selective HDAC1 or HDAC2 degraders that could leverage HDAC1/2 synthetic lethality to target NuRD vulnerabilities. Altogether, we identify HDAC1/2 collateral synthetic lethality as a potential therapeutic target and reveal an unexplored mechanism for targeting NuRD-associated cancer dependencies.

Dissecting the roles of MBD2 isoforms and domains in regulating NuRD complex function during cellular differentiation.

The Nucleosome Remodeling and Deacetylation (NuRD) complex is a crucial regulator of cellular differentiation. Two members of the Methyl-CpG-binding domain (MBD) protein family, MBD2 and MBD3, are known to be integral, but mutually exclusive subunits of the NuRD complex. Several MBD2 and MBD3 isoforms are present in mammalian cells, resulting in distinct MBD-NuRD complexes. Whether these different complexes serve distinct functional activities during differentiation is not fully explored. Based on the essential role of MBD3 in lineage commitment, we systematically investigated a diverse set of MBD2 and MBD3 variants for their potential to rescue the differentiation block observed for mouse embryonic stem cells (ESCs) lacking MBD3. While MBD3 is indeed crucial for ESC differentiation to neuronal cells, it functions independently of its MBD domain. We further identify that MBD2 isoforms can replace MBD3 during lineage commitment, however with different potential. Full-length MBD2a only partially rescues the differentiation block, while MBD2b, an isoform lacking an N-terminal GR-rich repeat, fully rescues the Mbd3 KO phenotype. In case of MBD2a, we further show that removing the methylated DNA binding capacity or the GR-rich repeat enables full redundancy to MBD3, highlighting the synergistic requirements for these domains in diversifying NuRD complex function.

The NuRD Complex in Neurodevelopment and Disease: A Case of Sliding Doors.

The Nucleosome Remodelling and Deacetylase (NuRD) complex represents one of the major chromatin remodelling complexes in mammalian cells, uniquely coupling the ability to "open" the chromatin by inducing nucleosome sliding with histone deacetylase activity. At the core of the NuRD complex are a family of ATPases named CHDs that utilise the energy produced by the hydrolysis of the ATP to induce chromatin structural changes. Recent studies have highlighted the prominent role played by the NuRD in regulating gene expression during brain development and in maintaining neuronal circuitry in the adult cerebellum. Importantly, components of the NuRD complex have been found to carry mutations that profoundly affect neurological and cognitive development in humans. Here, we discuss recent literature concerning the molecular structure of NuRD complexes and how the subunit composition and numerous permutations greatly determine their functions in the nervous system. We will also discuss the role of the CHD family members in an array of neurodevelopmental disorders. Special emphasis will be given to the mechanisms that regulate the NuRD complex composition and assembly in the cortex and how subtle mutations may result in profound defects of brain development and the adult nervous system.

Missense Mutation in Human CHD4 Causes Ventricular Noncompaction by Repressing ADAMTS1.

BACKGROUND: Left ventricular noncompaction (LVNC) is a prevalent cardiomyopathy associated with excessive trabeculation and thin compact myocardium. Patients with LVNC are vulnerable to cardiac dysfunction and at high risk of sudden death. Although sporadic and inherited mutations in cardiac genes are implicated in LVNC, understanding of the mechanisms responsible for human LVNC is limited. METHODS: We screened the complete exome sequence database of the Pediatrics Cardiac Genomics Consortium and identified a cohort with a de novo CHD4 (chromodomain helicase DNA-binding protein 4) proband, CHD4M202I, with congenital heart defects. We engineered a humanized mouse model of CHD4M202I (mouse CHD4M195I). Histological analysis, immunohistochemistry, flow cytometry, transmission electron microscopy, and echocardiography were used to analyze cardiac anatomy and function. Ex vivo culture, immunopurification coupled with mass spectrometry, transcriptional profiling, and chromatin immunoprecipitation were performed to deduce the mechanism of CHD4M195I-mediated ventricular wall defects. RESULTS: CHD4M195I/M195I mice developed biventricular hypertrabeculation and noncompaction and died at birth. Proliferation of cardiomyocytes was significantly increased in CHD4M195I hearts, and the excessive trabeculation was associated with accumulation of ECM (extracellular matrix) proteins and a reduction of ADAMTS1 (ADAM metallopeptidase with thrombospondin type 1 motif 1), an ECM protease. We rescued the hyperproliferation and hypertrabeculation defects in CHD4M195I hearts by administration of ADAMTS1. Mechanistically, the CHD4M195I protein showed augmented affinity to endocardial BRG1 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 4). This enhanced affinity resulted in the failure of derepression of Adamts1 transcription such that ADAMTS1-mediated trabeculation termination was impaired. CONCLUSIONS: Our study reveals how a single mutation in the chromatin remodeler CHD4, in mice or humans, modulates ventricular chamber maturation and that cardiac defects associated with the missense mutation CHD4M195I can be attenuated by the administration of ADAMTS1.

ZEB1 Is Regulated by K811 Acetylation to Promote Stability, NuRD Complex Interactions, EMT, and NSCLC Metastasis.

Epithelial-to-mesenchymal transition results in loss of specialized epithelial cell contacts and acquisition of mesenchymal invasive capacity. The transcription repressor zinc finger E-box-binding homeobox 1 (ZEB1) binds to E-boxes of gene promoter regions to suppress the expression of epithelial genes. ZEB1 has inconsistent molecular weights, which have been attributed to posttranslational modifications (PTM). We performed mass spectrometry and identified K811 acetylation as a novel PTM in ZEB1. To define the role of ZEB1 acetylation in regulating function, we generated ZEB1 acetyl-mimetic (K811Q) and acetyl-deficient (K811R) mutant-expressing non-small cell lung cancer cell lines (NSCLC). We demonstrate that the K811R ZEB1 (125 kDa) has a shorter protein half-life than wild-type (WT) ZEB1 and K811Q ZEB1 (∼225 kDa), suggesting that lack of ZEB1 acetylation in the lower molecular weight form affects protein stability. Further, the acetylated form of ZEB1 recruits the nucleosome remodeling and deacetylase (NuRD) complex to bind the promoter of its target genes mir200c-141 and SEMA3F. RNA-sequencing revealed that WT ZEB1 and K811Q ZEB1 downregulate the expression of epithelial genes to promote lung adenocarcinoma invasion and metastasis, whereas the K811R ZEB1 does not. Our findings establish that the K811 acetylation promotes ZEB1 protein stability, interaction with other protein complexes, and subsequent invasion/metastasis of lung adenocarcinoma via epithelial-to-mesenchymal transition. IMPLICATIONS: The molecular mechanisms by which ZEB1 is regulated by K811 acetylation to promote protein stability, NuRD complex and promoter interactions, and function are relevant to the development of treatment strategies to prevent and treat metastasis in patients with NSCLC.

Transcriptional derepression of CHD4/NuRD-regulated genes in the muscle of patients with dermatomyositis and anti-Mi2 autoantibodies.

OBJECTIVES: Myositis is a heterogeneous family of diseases including dermatomyositis (DM), immune-mediated necrotising myopathy (IMNM), antisynthetase syndrome (AS) and inclusion body myositis (IBM). Myositis-specific autoantibodies define different subtypes of myositis. For example, patients with anti-Mi2 autoantibodies targeting the chromodomain helicase DNA-binding protein 4 (CHD4)/NuRD complex (a transcriptional repressor) have more severe muscle disease than other DM patients. This study aimed to define the transcriptional profile of muscle biopsies from anti-Mi2-positive DM patients. METHODS: RNA sequencing was performed on muscle biopsies (n=171) from patients with anti-Mi2-positive DM (n=18), DM without anti-Mi2 autoantibodies (n=32), AS (n=18), IMNM (n=54) and IBM (n=16) as well as 33 normal muscle biopsies. Genes specifically upregulated in anti-Mi2-positive DM were identified. Muscle biopsies were stained for human immunoglobulin and protein products corresponding to genes specifically upregulated in anti-Mi2-positive muscle biopsies. RESULTS: A set of 135 genes, including SCRT1 and MADCAM1, was specifically overexpressed in anti-Mi2-positive DM muscle. This set was enriched for CHD4/NuRD-regulated genes and included genes that are not otherwise expressed in skeletal muscle. The expression levels of these genes correlated with anti-Mi2 autoantibody titres, markers of disease activity and with the other members of the gene set. In anti-Mi2-positive muscle biopsies, immunoglobulin was localised to the myonuclei, MAdCAM-1 protein was present in the cytoplasm of perifascicular fibres, and SCRT1 protein was localised to myofibre nuclei. CONCLUSIONS: Based on these findings, we hypothesise that anti-Mi2 autoantibodies could exert a pathogenic effect by entering damaged myofibres, inhibiting the CHD4/NuRD complex, and subsequently derepressing the unique set of genes defined in this study.

De novo variants in GATAD2A in individuals with a neurodevelopmental disorder: GATAD2A-related neurodevelopmental disorder.

GATA zinc finger domain containing 2A (GATAD2A) is a subunit of the nucleosome remodeling and deacetylase (NuRD) complex. NuRD is known to regulate gene expression during neural development and other processes. The NuRD complex modulates chromatin status through histone deacetylation and ATP-dependent chromatin remodeling activities. Several neurodevelopmental disorders (NDDs) have been previously linked to variants in other components of NuRD's chromatin remodeling subcomplex (NuRDopathies). We identified five individuals with features of an NDD that possessed de novo autosomal dominant variants in GATAD2A. Core features in affected individuals include global developmental delay, structural brain defects, and craniofacial dysmorphology. These GATAD2A variants are predicted to affect protein dosage and/or interactions with other NuRD chromatin remodeling subunits. We provide evidence that a GATAD2A missense variant disrupts interactions of GATAD2A with CHD3, CHD4, and CHD5. Our findings expand the list of NuRDopathies and provide evidence that GATAD2A variants are the genetic basis of a previously uncharacterized developmental disorder.

The NuRD complex cooperates with SALL4 to orchestrate reprogramming.

Cell fate decision involves rewiring of the genome, but remains poorly understood at the chromatin level. Here, we report that chromatin remodeling complex NuRD participates in closing open chromatin in the early phase of somatic reprogramming. Sall4, Jdp2, Glis1 and Esrrb can reprogram MEFs to iPSCs efficiently, but only Sall4 is indispensable capable of recruiting endogenous components of NuRD. Yet knocking down NuRD components only reduces reprogramming modestly, in contrast to disrupting the known Sall4-NuRD interaction by mutating or deleting the NuRD interacting motif at its N-terminus that renders Sall4 inept to reprogram. Remarkably, these defects can be partially rescured by grafting NuRD interacting motif onto Jdp2. Further analysis of chromatin accessibility dynamics demonstrates that the Sall4-NuRD axis plays a critical role in closing the open chromatin in the early phase of reprogramming. Among the chromatin loci closed by Sall4-NuRD encode genes resistant to reprogramming. These results identify a previously unrecognized role of NuRD in reprogramming, and may further illuminate chromatin closing as a critical step in cell fate control.