ABSTRACT: BRG1 recruitment by transcription factors MITF and SOX10 defines a specific configuration of regulatory elements in the melanocyte lineage (RNA-seq)
Project description:BRG1 recruitment by transcription factors MITF and SOX10 defines a specific configuration of regulatory elements in the melanocyte lineage (RNA-seq)
Project description:Microphthalmia-associated transcription factor (MITF) is the master regulator of the melanocyte lineage. By tandem affinity purification and mass spectrometry, we present a comprehensive characterisation of the MITF interactome comprising multiple novel cofactors involved in transcription, DNA replication and repair and chromatin organisation, including a BRG1 chromatin remodelling complex comprising CHD7. BRG1 is essential for melanoma cell proliferation in vitro and for normal melanocyte development in vivo. MITF and SOX10 actively recruit BRG1 to a set of MITF-associated regulatory elements (MAREs) at active enhancers. MITF, SOX10 and YY1 bind between two BRG1-occupied nucleosomes thus defining both a combinatorial signature of transcription factors essential for the melanocyte lineage and a specific chromatin organisation of MAREs. Nevertheless, BRG1 silencing enhances MITF occupancy at MAREs showing that BRG1 acts to promote dynamic MITF interactions with chromatin. 8 samples corresponding to genomic occupancy profiling of MITF, SOX10, BRG1 after si-control, BRG1 after si-MITF and BRG1 after siSOX10; and their respective controls (MITF Input, SOX10 Input, GFP-siCTRL ChIPseq) in 501Mel cells.
Project description:Microphthalmia-associated transcription factor (MITF) is the master regulator of the melanocyte lineage. By tandem affinity purification and mass spectrometry, we present a comprehensive characterisation of the MITF interactome comprising multiple novel cofactors involved in transcription, DNA replication and repair and chromatin organisation, including a BRG1 chromatin remodelling complex comprising CHD7. BRG1 is essential for melanoma cell proliferation in vitro and for normal melanocyte development in vivo. MITF and SOX10 actively recruit BRG1 to a set of MITF-associated regulatory elements (MAREs) at active enhancers. MITF, SOX10 and YY1 bind between two BRG1-occupied nucleosomes thus defining both a combinatorial signature of transcription factors essential for the melanocyte lineage and a specific chromatin organisation of MAREs. Nevertheless, BRG1 silencing enhances MITF occupancy at MAREs showing that BRG1 acts to promote dynamic MITF interactions with chromatin. 19 samples corresponding to mRNA profiles of 501Mel and Hermes3A after MITF, BRG1 or control shRNA-mediated knockdown were generated by deep sequencing in triplicate (in duplicate for 501_shMITF and corresponding control 501_shSCR2), using HiSeq2500.
Project description:BRG1 recruitment by transcription factors MITF and SOX10 defines a specific configuration of regulatory elements in the melanocyte lineage
Project description:Microphthalmia-associated transcription factor (MITF) is the master regulator of the melanocyte lineage. By tandem affinity purification and mass spectrometry, we present a comprehensive characterisation of the MITF interactome comprising multiple novel cofactors involved in transcription, DNA replication and repair and chromatin organisation, including a BRG1 chromatin remodelling complex comprising CHD7. BRG1 is essential for melanoma cell proliferation in vitro and for normal melanocyte development in vivo. MITF and SOX10 actively recruit BRG1 to a set of MITF-associated regulatory elements (MAREs) at active enhancers. MITF, SOX10 and YY1 bind between two BRG1-occupied nucleosomes thus defining both a combinatorial signature of transcription factors essential for the melanocyte lineage and a specific chromatin organisation of MAREs. Nevertheless, BRG1 silencing enhances MITF occupancy at MAREs showing that BRG1 acts to promote dynamic MITF interactions with chromatin.
Project description:Microphthalmia-associated transcription factor (MITF) is the master regulator of the melanocyte lineage. By tandem affinity purification and mass spectrometry, we present a comprehensive characterisation of the MITF interactome comprising multiple novel cofactors involved in transcription, DNA replication and repair and chromatin organisation, including a BRG1 chromatin remodelling complex comprising CHD7. BRG1 is essential for melanoma cell proliferation in vitro and for normal melanocyte development in vivo. MITF and SOX10 actively recruit BRG1 to a set of MITF-associated regulatory elements (MAREs) at active enhancers. MITF, SOX10 and YY1 bind between two BRG1-occupied nucleosomes thus defining both a combinatorial signature of transcription factors essential for the melanocyte lineage and a specific chromatin organisation of MAREs. Nevertheless, BRG1 silencing enhances MITF occupancy at MAREs showing that BRG1 acts to promote dynamic MITF interactions with chromatin.
Project description:BRG1 recruitment by transcription factors MITF and SOX10 defines a specific configuration of regulatory elements in the melanocyte lineage (ChIP-seq)
Project description:Somatic oncogenic mutation of BRAF coupled with inactivation of PTEN constitute a frequent combination of genomic alterations driving development of human melanoma. Mice genetically engineered to conditionally express oncogenic BrafV600E and inactivate Pten in melanocytes following tamoxifen treatment rapidly develop melanoma. While early stage melanomas comprised melanin-pigmented Mitf and Dct-expressing cells, expression of these and other melanocyte identity genes was lost in later stage tumours that showed histological and molecular characteristics of de-differentiated neural crest type cells. Melanocyte identity genes displayed loss of active chromatin marks and RNA polymerase II and gain of heterochromatin marks indicating epigenetic reprogramming during tumour progression. Nevertheless, late stage tumour cells grown in culture re-expressed Mitf and melanocyte markers and Mitf together with Sox10 co-regulated a large number of genes essential for their growth. In this melanoma model, somatic inactivation that the catalytic Brg1 (Smarca4) subunit of the SWI/SNF complex and the scaffolding Bptf subunit of the NuRF delayed tumour formation and deregulated large and overlapping gene expression programs essential for normal tumour cell growth. Moreover, we show that Brg1 and Bptf co-regulated many genes together with Mitf and Sox10. Together these transcription factors and chromatin remodelling complexes orchestrate essential gene expression programs in mouse melanoma cells
Project description:We have used a mouse model where melanoma can be induced by Tamoxifen treatment that induces expression of oncogenic Braf and deletion of Pten in the melanocyte lineage using a Tyr::Cre-ER-T2 transgene to mediate recombination. Cells from these melanoma tumours were cultured in vitro and the effects of siRNA mediated silencing of transcription factors Mitf and Sox10 was performed and analysed by RNA-seq. We then crossed these mice with mice bearing floxed alleles of the genes encoding the chromatin remodelling factors Bptf and Brg1 (Smarca4). Tumour cells were grown in culture and Bptf or Brg1 inactivated by 4-OHT treatment. The effects on gene expression were assessed by RNA-seq.
Project description:We performed ChIP-Seq analysis of SOX10, histone H3 lysine 27 acetylation (H3K27ac) and H3K27 trimethylation (H3K27me3) in melanocytes to profile the genomic binding sites of SOX10 and the chromatin landscape. In parallel, we generated Sox10 haploinsufficient cell lines using gene knockout approaches and conducted microarray gene expression analysis to identify functional gene targets of SOX10 transcriptional regulation in melanocytes. We demonstrate that SOX10 predominantly engages “open” chromatin, binds to melanocyte enhancer elements and plays a central role in transcriptional activation and repression of functionally distinct classes of genes. Furthermore, we identified cis-regulatory sequence motifs of putative co-regulatory transcription factors that define SOX10-activated and SOX10-repressed target genes. Our results uncover novel mechanisms and roles of SOX10 in global transcriptional regulation of diverse regulatory pathways in the melanocyte lineage. ChIP-seq profiling of SOX10, H3K27ac, and H3K27me3 in the mouse melanocyte cell line melan-Ink4a-Arf-1 (melan-a).