Project description:The basic helix-loop-helix transcription factor Twist1 has a well-documented role in mesenchymal populations of the developing embryo, such as endocardial cushion (ECC) mesenchymal cells and limb buds, and during cancer development and progression. Whether Twist1 regulates the same transcriptional targets in different cell types has yet to be investigated. Through chromatin immunoprecipitation followed by sequencing (Chip-seq) analysis, the cell type-specific genome-wide occupancy of Twist1 was investigated in ECCs, limb buds and mouse peripheral nerve sheath tumor (PNST) cells. Twist1 binds mainly in a cell type-specific manner, with very few common genomic regions occupied by Twist1 in different cell types. Genes associated with binding peaks in each cell type are related to known Twist1 cellular functions in ECCs, limb buds, and cancer cells. We found that cell type-specific binding of Twist1 may be influenced by histone modifications or co-factors. Binding regions were located in several Wnt pathway associated genes, supporting a link between Twist1 and Wnt signalling in ECCs, limb buds, and PNST cells. These data suggest that similar functions are regulated by Twist1 in ECCs, limb buds, and PNST cells in a cell type-specific manner, and provide insights into possible mechanisms utilized for cell type-specificity of Twist1 binding. We compare Twist1 genome occupancy in mouse embryonic day (E) 12.5 endocardial cushion mesenchymal cells, E10.5 forelimb buds, and a mouse peripheral nerve sheath tumor cell line.
Project description:The basic helix-loop-helix transcription factor Twist1 has a well-documented role in mesenchymal populations of the developing embryo, such as endocardial cushion (ECC) mesenchymal cells and limb buds, and during cancer development and progression. Whether Twist1 regulates the same transcriptional targets in different cell types has yet to be investigated. Through chromatin immunoprecipitation followed by sequencing (Chip-seq) analysis, the cell type-specific genome-wide occupancy of Twist1 was investigated in ECCs, limb buds and mouse peripheral nerve sheath tumor (PNST) cells. Twist1 binds mainly in a cell type-specific manner, with very few common genomic regions occupied by Twist1 in different cell types. Genes associated with binding peaks in each cell type are related to known Twist1 cellular functions in ECCs, limb buds, and cancer cells. We found that cell type-specific binding of Twist1 may be influenced by histone modifications or co-factors. Binding regions were located in several Wnt pathway associated genes, supporting a link between Twist1 and Wnt signalling in ECCs, limb buds, and PNST cells. These data suggest that similar functions are regulated by Twist1 in ECCs, limb buds, and PNST cells in a cell type-specific manner, and provide insights into possible mechanisms utilized for cell type-specificity of Twist1 binding.
Project description:Twist1, a basic helix-loop-helix transcription factor, is expressed in mesenchymal precursor populations during embryogenesis and in metastatic cancer cells. In the developing heart, Twist1 is highly expressed in endocardial cushion (ECC) valve mesenchymal cells and is down regulated during valve differentiation and remodeling. Previous studies demonstrated that Twist1 promotes cell proliferation, migration, and expression of primitive ECM molecules in ECC mesenchymal cells. Furthermore, Twist1 expression is induced in human pediatric and adult diseased heart valves. However, the Twist1 downstream target genes that mediate increased cell proliferation and migration during early heart valve development remain largely unknown. Candidate gene and global gene profiling approaches were used to identify direct transcriptional targets of Twist1 during heart valve development. Candidate target genes were analyzed for evolutionarily conserved regions (ECRs) containing E-box consensus sequences that are potential Twist1 binding sequences. ECRs containing conserved E-box sequences were identified for Twist1 responsive genes Tbx20, Cdh11, Sema3C, Rab39b, and Gadd45a. Twist1 binding to these sequences in vivo was determined by chromatin immunoprecipitation assays, and binding was detected in ECCs but not late stage remodeling valves. In addition identified Twist1 target genes are highly expressed in ECCs and have reduced expression during heart valve remodeling in vivo which is consistent with the expression pattern of Twist1. Together these analyses identify multiple new genes involved in cell proliferation and migration that are differentially expressed in the developing heart valves, are responsive to Twist1 transcriptional function, and contain Twist1 responsive regulatory sequences.
Project description:Twist1, a basic helix-loop-helix transcription factor, is expressed in mesenchymal precursor populations during embryogenesis and in metastatic cancer cells. In the developing heart, Twist1 is highly expressed in endocardial cushion (ECC) valve mesenchymal cells and is down regulated during valve differentiation and remodeling. Previous studies demonstrated that Twist1 promotes cell proliferation, migration, and expression of primitive ECM molecules in ECC mesenchymal cells. Furthermore, Twist1 expression is induced in human pediatric and adult diseased heart valves. However, the Twist1 downstream target genes that mediate increased cell proliferation and migration during early heart valve development remain largely unknown. Candidate gene and global gene profiling approaches were used to identify direct transcriptional targets of Twist1 during heart valve development. Candidate target genes were analyzed for evolutionarily conserved regions (ECRs) containing E-box consensus sequences that are potential Twist1 binding sequences. ECRs containing conserved E-box sequences were identified for Twist1 responsive genes Tbx20, Cdh11, Sema3C, Rab39b, and Gadd45a. Twist1 binding to these sequences in vivo was determined by chromatin immunoprecipitation assays, and binding was detected in ECCs but not late stage remodeling valves. In addition identified Twist1 target genes are highly expressed in ECCs and have reduced expression during heart valve remodeling in vivo which is consistent with the expression pattern of Twist1. Together these analyses identify multiple new genes involved in cell proliferation and migration that are differentially expressed in the developing heart valves, are responsive to Twist1 transcriptional function, and contain Twist1 responsive regulatory sequences. Murine MC3T3-E1 preosteoblast cells were treated with siScrambled control or siTwist1 to achieve knockdown of Twist1. Both siScr and siTwist1 were performed in triplicate. Isolated RNA was analyzed with Affymetrix muring MOE 430 2.0 gene chip microarray.
Project description:Heart valve formation initiates when endothelial cells of the heart transform into mesenchyme and populate the cardiac cushions. The transcription factor, SOX9, is highly expressed in the cardiac cushion mesenchyme, and is essential for heart valve development. Loss of Sox9 in mouse cardiac cushion mesenchyme alters cell proliferation, embryonic survival, and disrupts valve formation. Despite this important role, little is known regarding how SOX9 regulates heart valve formation or its transcriptional targets. Therefore, we mapped putative SOX9 binding sites by ChIP-Seq in embryonic day (E) 12.5 heart valves, a stage at which the valve mesenchyme is actively proliferating and initiating differentiation. Embryonic heart valves have been shown to express a high number of genes that are associated with chondrogenesis, including several extracellular matrix proteins and transcription factors that regulate chondrogenesis. Consequently, we compared regions of putative SOX9 DNA-binding between E12.5 heart valves and E12.5 limb buds. We identified context-dependent and contextâindependent SOX9 interacting regions throughout the genome. Analysis of context-independent SOX9 binding suggests an extensive role for SOX9 across tissues in regulating proliferation-associated genes including key components of the AP-1 complex. Integrative analysis of tissue-specific SOX9 interacting regions and gene expression profiles on Sox9-deficient heart valves demonstrated that SOX9 controls the expression of several transcription factors with previously identified roles in heart valve development, including Twist1, Sox4, Mecom/Evi1 and Pitx2. Together, our data identifies SOX9 coordinated transcriptional hierarchies that control cell proliferation and differentiation during valve formation. Examination of SOX9 binding sites in E12.5 atrioventricular canal (AVC) and E12.5 embryonic limb and mRNA expression profiling in E12.5 WT and Sox9 mutant AVCs, in duplicate.
Project description:Malignant peripheral nerve sheath tumor (MPNST) is an aggressive sarcoma. Comprehensive proteomic profiles of 23 MPNST tumor specimens were obtained using LC-MS/MS. Among 23 tumor specimens, 13 patients showed favorable prognosis and 10 did local recurrence/distant metastasis.