Chromosome conformation capture-on-chip analysis of long-range cis interactions of the SOX9 promoter
ABSTRACT: Transcription factor SOX9 is essential for the differentiation of chondrocytes and the development of testes. Heterozygous point mutations and genomic deletions involving SOX9 lead to campomelic dysplasia (CD) often associated with sex reversal. Chromosomal rearrangements with breakpoints mapping up to 1.3 Mb up- and downstream to SOX9, and likely disrupting its distant cis-regulatory elements, have been described in patients with milder forms of CD. Performing chromosome conformation capture-on-chip (4C) analysis in Sertoli cells and lymphoblasts we identified several novel potentially cis-interacting regions both up- and downstream to SOX9, with some of them overlapping lncRNA genes preferentially expressed in testes. Custom designed 3x720K tiling microarrays covering 4 Mb region (chr17:68,117,161-72,122,560) flanking SOX9 gene of interest
Project description:Heterozygous point mutations or genomic deletions of NR0B1 in Xp21.2 result in congenital adrenal hypoplasia and hypogonadotropic hypogonadism, whereas the NR0B1 locus duplications in XY individuals lead to gonadal dysgenesis and a male-to-female dosage-sensitive sex reversal. We previously reported an ~ 257 kb deletion mapping 11 kb upstream to NR0B1 in a XY female with primary amenorrhea, small immature uterus, and gonadal dysgenesis pointing to an alteration of its regulatory region. To identify the potential regulatory elements of NR0B1, we have analyzed its 2 Mb flanking regions using chromosome conformation capture-on-chip (4C) in Sertoli cells and lymphoblasts. We confirm the involvement of the previously proposed regulatory region in the control of NR0B1 expression and describe several novel potential chromatin interactions within the NR0B1 locus that may be involved in sex differentiation. Custom designed 3x720K tiling microarrays covering 4 Mb region (chrX:28,082,100-32,087,100) flanking NR0B1 gene of interest
Project description:To determine if there is a physical interaction between the FOXF1 promoter and putative enhancer sequences ~250kb upstream of the promoter chromosome conformation capture-on-chip (4C) analysis was performed. An unanticipated and tremendous amount of the non-coding sequences of the human genome are transcribed. Long non-coding RNAs (lncRNAs) are non-protein coding transcripts longer than 200 nucleotides and their functions remain enigmatic. We demonstrate that deletions of lncRNA genes cause a lethal lung developmental disorder, Alveolar Capillary Dysplasia with Misalignment of Pulmonary Veins (ACD/MPV), with parent of origin effects. We identify non-coding overlapping deletions 250 kb upstream to FOXF1 in nine patients with ACD/MPV that arose de novo specifically on the maternally inherited chromosome and delete a fetal lung-specific EST, part of an lncRNA. These deletions define distant cis-regulatory region that harbors a differentially methylated CpG island, binds GLI2 depending on the methylation status of this CpG island, and physically interacts with and up-regulates the FOXF1 promoter, consistent with the absence of the fetal lung-transcribed lncRNA perturbing FOXF1 regulation. LncRNA-mediated chromatin interactions may be responsible for position effect phenomenon and potentially cause many disorders of human development. 4C analysis using 16q24.1 specific 3x720K arrays demonstrated physical interaction between the FOXF1 promoter and distant putative regulatory sequences, about 250 kb upstream in human pulomonary microvascular endothelial cells; 2 biological replicates performed; this chromatin looping was not detected in lymphoblasts that do not express FOXF1 and hence serve as a negative control.
Project description:Reuse of materials in DNA hybridization based methods has been known since the advent of Southern membranes. Array based comparative genomic hybridization is essentially Southern hybridization with multiple probes immobilized on a solid surface. We have shown that comparative genomic hybridization microarrays fabricated with maskless array synthesizer technology can be used up to four times with application of 1,3-dimethylurea as array-stripping agent. We reproducibly detected chromosomal aberrations, 0.6 to 22.4 Mb in size, in four hybridization rounds using regenerated microarray slides. We have also demonstrated that regenerated arrays can detect smaller alterations, 16 – 200 kbp, such as common copy number variants, as well as complex aberration profiles in tumor. Peripheral blood leukocyte DNA samples from 7 individuals with subchromosomal aberrations vs a pool of female DNA (Promega). The experiments were performed in quadruplicate on succesively regenerated microarrays. One dye swap was performed..
Project description:Epidermal Growth Factor Receptor (EGFR) gene amplification and mutations are the most common oncogenic events in Glioblastoma (GBM), but the mechanisms by which they promote aggressive tumor growth are not well understood. Here, through integrated epigenome and transcriptome analyses of cell lines, genotyped clinical samples and TCGA data, we show that EGFR mutations remodel the activated enhancer landscape of GBM, promoting tumorigenesis through a SOX9 and FOXG1-dependent transcriptional regulatory network in vitro and in vivo. The most common EGFR mutation, EGFRvIII, sensitizes GBM cells to the BET-bromodomain inhibitor JQ1 in a SOX9, FOXG1-dependent manner. These results identify the role of transcriptional/epigenetic remodeling in EGFR-dependent pathogenesis and suggest a mechanistic basis for epigenetic therapy. ChIP-Seq for H3K27ac, H3K4me1, and H3K4me3, and RNA-seq for Glioblastoma (GBM) cells and/or tissues with or without EGFRvIII mutation.
Project description:The immunoglobulin heavy-chain (Igh) locus undergoes large-scale contraction in pro-B cells, which facilitates VH-DJH recombination by juxtaposing distal VH genes next to the DJH- rearranged gene segment in the proximal Igh domain. By high-resolution mapping of long-range interactions, we now demonstrate that an array of local interaction domains establishes the three- dimensional structure of the extended Igh locus in lymphoid progenitors and thymocytes. In pro- B cells, these local domains engage in long-range interactions across the entire Igh locus, which depend on the transcription factors Pax5, YY1 and CTCF. The large VH gene cluster thereby undergoes flexible long-range interactions with the more rigidly structured 3’ proximal domain, which ensures that all VH genes can participate with similar probability in VH-DJH recombination to generate a diverse antibody repertoire. Notably, these long-range interactions appear to be an intrinsic feature of the VH gene cluster, as they are still generated upon mutation of the Eμ enhancer, IGCR1 insulator or 3’ regulatory region present in the 3’ proximal Igh domain. 4C sequencing from mutliple celltypes with multiple viewpoints; uneven number of replicates ChIP-Seq
Project description:Cancer cells frequently depend on chromatin regulatory activities to maintain a malignant phenotype. Here, we show that leukemia cells require the mammalian SWI/SNF chromatin remodeling complex for their survival and aberrant self-renewal potential. While Brg1, an ATPase subunit of SWI/SNF, is known to suppress tumor formation in several cancer types, we found that leukemia cells instead rely on Brg1 to support their oncogenic transcriptional program, which includes Myc as one of its key targets. To account for this context-specific function, we identify a cluster of lineage-specific enhancers located 1.7 megabases downstream of Myc that are occupied by SWI/SNF, as well as the BET protein Brd4. Brg1 is required at these distal elements to maintain transcription factor occupancy and for long-range chromatin looping interactions with the Myc promoter. Notably, these distal Myc enhancers coincide with a region that is focally amplified in 3% of acute myeloid leukemia. Together, these findings define a leukemia maintenance function for SWI/SNF that is linked to enhancer-mediated gene regulation, providing general insights into how cancer cells exploit transcriptional coactivators to maintain oncogenic gene expression programs Enhancer usually regulates its targets through physical contact/interaction. In order to study chromosome conformation of Myc locus and potential distal enhancer E1-E5 region in murine AML cells, we utilize the high resolution 4C-seq and analysis pipeline to search cis elements that physical interact with Myc and E1-E5 region through setting up two individual viewpoints in these two regions.
Project description:The Lhx2 transcription factor plays essential roles in morphogenesis and patterning of ectodermal derivatives, as well as in controlling stem cell activity. Lhx2 is expressed in the hair follicle (HF) buds, while in postnatal telogen HFs Lhx2+ cells reside in the stem cell-enriched epithelial compartments (bulge, secondary hair germ) and co-express selected stem cell markers (Sox9, Tcf4 and Lgr5). Lhx2+ cells represent the vast majority of cells in the bulge and secondary hair germ that proliferate in response to skin injury. This is functionally important, since the wound re-epithelialization is significantly retarded in heterozygous Lhx2 knockout (+/-) mice, while anagen onset in the HFs located closely to the wound is accelerated compared to wild-type mice. Cell proliferation in the bulge and the number of Sox9+ and Tcf4+ cells in the HFs closely adjacent to the wound in Lhx2+/- mice are decreased in comparison to wild-type controls, while expression of Lgr5 and cell proliferation in the secondary hair germ are increased. Furthermore, acceleration of wound-induced anagen development in Lhx2+/- mice is inhibited by administration of Lgr5 siRNA. In addition, Chip-on-chip/ChIP-qPCR and reporter assay analyses reveal Sox9, Tcf4 and Lgr5 as direct Lhx2 targets in keratinocytes. These data strongly suggest that Lhx2 positively regulates Sox9 and Tcf4 in the bulge cells and promotes wound re-epithelization, while it simultaneously negatively regulates Lgr5 in the secondary hair germ and inhibits HF cycling. Thus, Lhx2 operates as a regulator of epithelial stem cell activity during skin response to injury. Chromatin form primary mouse keratinocytes (PMK) was subjected to ChIP analysis with Lhx2 antibody; input and ChIP DNA were labelled with Cy3 and Cy5 respectivly and used form Nimblegen MM8 Mouse Promoter Array
Project description:Immunoglobulin class switch recombination (CSR) is initiated by the transcription-coupled recruitment of activation induced cytidine deaminase (AID) to immunoglobulin switch (S) regions. During CSR, the IgH locus undergoes dynamic three-dimensional structural changes in which promoters, enhancers and S regions are brought to close proximity. Nevertheless, little is known about the underlying mechanisms. Here we conditionally inactivated in B cells the Med1 subunit of mediator, a complex implicated in transcription initiation and long-range enhancer/promoter loop formation. We find that Med1-deficiency results in defective CSR, reduced acceptor switch region transcription and that this correlates with reduced long-range interactions between the acceptor switch regions and the Em enhancer, as determined by 4C-Seq. Our results implicate the mediator complex in the mechanism of CSR and are consistent with a model in which Med1 facilitates the transcriptional activation of switch regions and their long-range contacts with the IgH locus enhancers during CSR. 4C-seq data in resting and activated WT and Med1 mutant B cells. 4C bait was designed in the Eu enhancer of the Igh locus on chromosome 12. Primer sequences: 5’ TCTGTCCTAAAGGCTCTGAGA 3’ and 5’ GAACACAGAAGTATGTGTATGGA 3’.
Project description:The paralogous genes Nppa and Nppb are organized in an evolutionary conserved cluster and are a valuable model to study coregulation and regulatory landscape organization during heart development and disease. Here, we analyzed the chromatin conformation, epigenetic status and enhancer potential of sequences of the Nppa-Nppb cluster in vivo. Our data indicate that the regulatory landscape of the cluster is present within a 60 kbp domain centered around Nppb. Both promoters and several potential regulatory elements interact with each other in a similar manner in different tissues and developmental stages. The distribution of H3K27ac and the association of Pol2 across the locus changed during cardiac hypertrophy, revealing their potential involvement in stress-mediated gene regulation. In summary, the developmental regulation and stress-response of the Nppa-Nppb cluster involve the concerted action of multiple enhancers and epigenetic changes distributed across a structurally rigid regulatory domain. We have used 4C-seq on several viewpoints around the Nppa-Nppb gene cluster in the heart and liver samples to investigate the role of chromatin conformation on regulation of Nppa and Nppb expression during heart development and disease.
Project description:Upon recruitment to active enhancers and promoters, RNA polymerase II (Pol_II) generates short non-coding transcripts of unclear function. The mechanisms that control the length and the amount of ncRNAs generated by cis-regulatory elements are largely unknown. Here, we show that the adapter protein WDR82 and its associated complexes actively limit such non-coding transcription. WDR82 targets the SET1/COMPASS H3K4 methyltransferase and the nuclear Protein Phosphatase 1 (PP1) complexes to the initiating Pol_II. WDR82 and PP1 also interact with components of the transcriptional termination and RNA processing machineries. Depletion of WDR82, SET1 or the PP1 subunit required for its nuclear import caused distinct but overlapping transcription termination defects at highly expressed genes, active enhancers and promoters, thus enabling the increased synthesis of unusually long ncRNAs. These data indicate that transcription initiated from cis-regulatory elements is tightly coordinated with termination mechanisms that impose the synthesis of short RNAs. 4C-seq was performed on four different viewpoints (either at the 5' or the 3' of the Mpeg1 and Lgals3 genes, indicated as sx or dx, respectively) in BMDMs. Experiments were carried out in cells containing either a short hairpin targeting Wdr82 or a scrambled as a control.