Project description:CHOPS syndrome is caused by germline gain-of-function mutations of AFF4. Cornelia de Lange syndrome is caused by germline mutations of cohesin loading factors or cohesin complex genes such as NIPBL, SMC1A, SMC3 and HDAC8. There are many overlapping clinical features exist between CHOPS syndrome and Cornelia de Lange syndrome. To identified commonly dysregulated genes in CHOPS syndrome and Cornelia de Lange syndrome, we perfomred side-by-side transcriptome comparison between CHOPS syndrome and Cornelia de Lange syndrome.
Project description:The cohesin protein complex is essential for the formation of topologically associating domains (TADs) and chromatin loops on interphase chromosomes. For the loading onto chromosomes, cohesin requires the cohesin loader complex formed by NIPBL and MAU2. Cohesin localizes at enhancers and gene promoters with NIPBL in mammalian cells and forms enhancer-promoter loops. Cornelia de Lange syndrome (CdLS) is a rare, genetically heterogeneous disorder affecting multiple organs and systems during development, caused by mutations in the cohesin loader NIPBL gene (> 60% of patients), as well as in genes encoding cohesin, a chromatin regulator, BRD4, and cohesin-related factors. We also reported CHOPS syndrome that phenotypically overlaps with CdLS and is caused by gene mutations of a super elongation complex (SEC) core component, AFF4. Although these syndromes are associated with transcriptional dysregulation, the underlying mechanism remains unclear. In this study, we provide the first comprehensive analysis of chromosome architectural changes caused by these mutations using cell lines derived from CdLS and CHOPS syndrome patients. In both patient cells, we found a decrease in cohesin, NIPBL, BRD4, and acetylation of lysine 27 on histone H3 (H3K27ac) in most enhancers with enhancer-promoter loop attenuation. In contrast, TADs were maintained in both patient cells. These findings reveal a shared molecular mechanism in these syndromes and highlight unexpected roles for cohesin, cohesin loaders, and the SEC in maintaining the enhancer complexes. These complexes are crucial for recruiting transcriptional regulators, sustaining active histone modifications, and facilitating enhancer-promoter looping.
Project description:The cohesin protein complex is essential for the formation of topologically associating domains (TADs) and chromatin loops on interphase chromosomes. For the loading onto chromosomes, cohesin requires the cohesin loader complex formed by NIPBL and MAU2. Cohesin localizes at enhancers and gene promoters with NIPBL in mammalian cells and forms enhancer-promoter loops. Cornelia de Lange syndrome (CdLS) is a rare, genetically heterogeneous disorder affecting multiple organs and systems during development, caused by mutations in the cohesin loader NIPBL gene (> 60% of patients), as well as in genes encoding cohesin, a chromatin regulator, BRD4, and cohesin-related factors. We also reported CHOPS syndrome that phenotypically overlaps with CdLS and is caused by gene mutations of a super elongation complex (SEC) core component, AFF4. Although these syndromes are associated with transcriptional dysregulation, the underlying mechanism remains unclear. In this study, we provide the first comprehensive analysis of chromosome architectural changes caused by these mutations using cell lines derived from CdLS and CHOPS syndrome patients. In both patient cells, we found a decrease in cohesin, NIPBL, BRD4, and acetylation of lysine 27 on histone H3 (H3K27ac) in most enhancers with enhancer-promoter loop attenuation. In contrast, TADs were maintained in both patient cells. These findings reveal a shared molecular mechanism in these syndromes and highlight unexpected roles for cohesin, cohesin loaders, and the SEC in maintaining the enhancer complexes. These complexes are crucial for recruiting transcriptional regulators, sustaining active histone modifications, and facilitating enhancer-promoter looping.
Project description:CHOPS syndrome is caused by germline gain-of-function mutations of AFF4. Cornelia de Lange syndrome is caused by germline mutations of cohesin loading factors or cohesin complex genes such as NIPBL, SMC1A, SMC3 and HDAC8. There are many overlapping clinical features exist between CHOPS syndrome and Cornelia de Lange syndrome. To identified commonly dysregulated genes in CHOPS syndrome and Cornelia de Lange syndrome, we perfomred side-by-side transcriptome comparison between CHOPS syndrome and Cornelia de Lange syndrome. In this transcriptome analysis, patient derived skin fibroblasts from two CHOPS syndrome probands, two Cornelia de Lange syndrome probands, and four age-gender-ethnicity matched healthy control subjects were used.The samples used for Human Gene 2.0 arrays are two CHOPs syndrome samples (CDL160 and CDL444), two Cornelia de Lange syndrome samples (CdL006: 7 year-old Caucasian female NIPBL 742_743delCT ;L248TfsX6 and CdL015: 10 year-old Caucasian male NIPBL 2969delG;G990DfsX2), and four age gender matched control samples (GM01652, GM01864, GM02036 and GM03348).
Project description:Cornelia de Lange Syndrome is a multisystem developmental disorder typically caused by mutations in the gene encoding the cohesin loader NIPBL. The associated phenotype is generally assumed to be the consequence of aberrant transcriptional regulation. Recently, we identified a residue substitution in BRD4 associated with a Cornelia de Lange-like Syndrome, that reduces BRD4 binding to acetylated histones. Here we show that, although this mutation reduces BRD4-enhancer interaction in mouse embryonic stem cells, it does not affect transcription. Rather it delays the cell cycle, increased DNA damage signalling, and perturbs regulation of DNA repair in mutant cells. This uncovers a new role for BRD4 in DNA repair pathway choice. Furthermore, we find evidence of a similar increase in DNA damage signalling in cells derived from NIPBL-deficient individuals, suggesting that defective DNA damage signalling and repair is also a feature of typical Cornelia de Lange Syndrome.
Project description:whole-genome aCGH analysis also showed us that the patient carried a 12.01-1M Mb deletion region at chromosome bands 9q31.1-q32 (105,190,105-117,195,154). The deleted region encompasses 22 genes including SMC2 Two-condition Samples, Cornelia de Lange Syndrome vs. Normal cells.
Project description:Cornelia de Lange syndrome (CdLS) is a complex multisystem developmental disorder caused by mutations in cohesin subunits and regulators. While the precise molecular mechanisms are not well defined, they point toward a global deregulation of the transcriptional gene expression program. Indeed, cohesin is associated with the boundaries of chromosome domains in addition to enhancers and promoters connecting the 3D genome organization with transcriptional control and gene expression. Here we show that connected gene communities, built with noncoding regulatory elements and genes physically interacting in the 3D chromosomal space, provide a molecular explanation for the pathoetiology of CdLS. Indeed, NIPBL and cohesin are important constituents of connected gene communities, both being centrally positioned at active noncoding regulatory elements. Interestingly, mutations in SMC1A and NIPBL lead to coordinated gene expression changes in connected communities. Our findings suggest a model where CdLS is explained by coordinated modulation of connected gene communities.
Project description:Heterozygous mutations in the cohesin regulator, NIPBL, or cohesin structural components SMC1A, and SMC3, result in Cornelia de Lange Syndrome (CdLS). Genome-wide transcription assessment has identified unique profiles of genes dysregulated in CdLS that correlate with different clinical presentations. Cohesin binding analysis demonstrates a preference for intergenic regions suggesting a cis-regulatory function mimicking that of an insulator. However, the binding sites are enriched within the promoter regions of the dysregulated genes and are significantly decreased in CdLS probands, indicating an alternative role of cohesin as a classic transcription factor. Keywords: ChIP-chip
Project description:We used SLIC-CAGE to map transcriptional start sites in cortical neurons from Cornelia de Lange Syndrome (CdLS) patients and control individuals. SLIC-CAGE was performed using nuclear RNA isolated from pre-frontal cortical grey matter. Usage of nuclear RNA allows enrichment of unstable RNAs, such as RNA originating from enhancer transcription. We characterised promoter-level gene expression in cortical neurons from CdLS patients and found deregulation of hundreds of genes enriched for neuronal functions.