Project description:The transcriptional activator MyoD serves as a master controller of myogenesis. Often in partnership with Mef2, MyoD binds to the promoters of hundreds of muscle genes in proliferating myoblasts, yet activates these targets only upon receiving cues that launch differentiation. What regulates this off/on switch of MyoD function has been incompletely understood, although known to reflect the action of chromatin modifiers. Here, we identify KAP1/TRIM28 as a key regulator of MyoD function. In myoblasts, KAP1 is present with MyoD and Mef2 at many muscle genes, where it acts as a scaffold to recruit not only co-activators such as p300 and LSD1, but also co-repressors such as G9a and HDAC1, with promoter silencing as net outcome. Upon differentiation, MSK1-mediated phosphorylation of KAP1 releases the co-repressors from the scaffold, unleashing transcriptional activation by MyoD/Mef2 and their positive cofactors. Thus, our results reveal KAP1 as a previously unappreciated interpreter of cell signaling, which modulates the ability of MyoD to drive myogenesis. Transcriptome profiling of control and Kap1KD in C2C12 during proliferation or at 48hours differentiation stage
Project description:The transcriptional activator MyoD serves as a master controller of myogenesis. Often in partnership with Mef2, MyoD binds to the promoters of hundreds of muscle genes in proliferating myoblasts, yet activates these targets only upon receiving cues that launch differentiation. What regulates this off/on switch of MyoD function has been incompletely understood, although known to reflect the action of chromatin modifiers. Here, we identify KAP1/TRIM28 as a key regulator of MyoD function. In myoblasts, KAP1 is present with MyoD and Mef2 at many muscle genes, where it acts as a scaffold to recruit not only co-activators such as p300 and LSD1, but also co-repressors such as G9a and HDAC1, with promoter silencing as net outcome. Upon differentiation, MSK1-mediated phosphorylation of KAP1 releases the co-repressors from the scaffold, unleashing transcriptional activation by MyoD/Mef2 and their positive cofactors. Thus, our results reveal KAP1 as a previously unappreciated interpreter of cell signaling, which modulates the ability of MyoD to drive myogenesis. Kap1 and H3K9me3 ChIPseq in proliferating C2C12 cells
Project description:The transcriptional activator MyoD serves as a master controller of myogenesis. Often in partnership with Mef2, MyoD binds to the promoters of hundreds of muscle genes in proliferating myoblasts, yet activates these targets only upon receiving cues that launch differentiation. What regulates this off/on switch of MyoD function has been incompletely understood, although known to reflect the action of chromatin modifiers. Here, we identify KAP1/TRIM28 as a key regulator of MyoD function. In myoblasts, KAP1 is present with MyoD and Mef2 at many muscle genes, where it acts as a scaffold to recruit not only co-activators such as p300 and LSD1, but also co-repressors such as G9a and HDAC1, with promoter silencing as net outcome. Upon differentiation, MSK1-mediated phosphorylation of KAP1 releases the co-repressors from the scaffold, unleashing transcriptional activation by MyoD/Mef2 and their positive cofactors. Thus, our results reveal KAP1 as a previously unappreciated interpreter of cell signaling, which modulates the ability of MyoD to drive myogenesis.
Project description:The transcriptional activator MyoD serves as a master controller of myogenesis. Often in partnership with Mef2, MyoD binds to the promoters of hundreds of muscle genes in proliferating myoblasts, yet activates these targets only upon receiving cues that launch differentiation. What regulates this off/on switch of MyoD function has been incompletely understood, although known to reflect the action of chromatin modifiers. Here, we identify KAP1/TRIM28 as a key regulator of MyoD function. In myoblasts, KAP1 is present with MyoD and Mef2 at many muscle genes, where it acts as a scaffold to recruit not only co-activators such as p300 and LSD1, but also co-repressors such as G9a and HDAC1, with promoter silencing as net outcome. Upon differentiation, MSK1-mediated phosphorylation of KAP1 releases the co-repressors from the scaffold, unleashing transcriptional activation by MyoD/Mef2 and their positive cofactors. Thus, our results reveal KAP1 as a previously unappreciated interpreter of cell signaling, which modulates the ability of MyoD to drive myogenesis.
Project description:In skeletal myogenesis, the transcription factor MyoD activates distinct transcriptional programs in progenitors compared to terminally differentiated cells. Using ChIP-seq and gene expression analyses, we show that in primary myoblasts, Snail-HDAC1/2 repressive complex bind and exclude MyoD from its targets. Notably, Snail binds E-box motifs that are G/C-rich in their central dinucleotides, and such sites are almost exclusively associated with genes expressed during differentiation. By contrast, Snail does not bind the A/T-rich E-boxes associated with MyoD targets in myoblasts. Thus, Snai1-HDAC1/2 prevents MyoD occupancy on differentiation-specific regulatory elements and the change from Snail- to MyoD-binding often results in enhancer switching during differentiation. Furthermore, we show that a regulatory network involving Myogenic Regulatory Factors (MRFs), Snail/2, miR-30a and miR-206 acts as a molecular switch that controls entry into myogenic differentiation. Together, these results reveal a regulatory paradigm that directs distinct gene expression programs in progenitors versus terminally differentiated cells. Genome wide binding sites of various transcription factors and chromatin modifiers in muscle cells
Project description:The transcription factor MyoD can coax na?e fibroblasts or otherwise committed cells to adopt the skeletal muscle phenotype by activating the muscle gene expression program. Activation of muscle gene expression occurs in quantal steps with not all the target genes of MyoD being activated at the same time. Some genes are induced in the initial phases, others at later stages despite the fact that MyoD is present throughout the differentiation process. MyoD is post-translationally modified by phosphorylation, ubiquitination, and acetylation. Here, we have employed a model system in which MyoD and its non-acetylatable version were inducibly expressed in mouse embryonic fibroblasts derived from mice to investigate how MyoD acetylation may contribute to differential gene activation. Experiment Overall Design: Mouse embryos fibroblasts (MEFs) obtained from MyoD-/-/Myf5-/- animals will be transduced with retroviruses expressing an estrogen receptor hormone binding domain fused to either mouse MyoD wild type (ER-MyoD wt) or MyoD bearing three point mutations at lysine residues 99, 102, and 104 that render it no longer acetylatable ( ER-MyoD RRR). A retrovirus without the ER-MyoD insert was also employed as negative control.</p> Aim 2. We will compare genome-wide expression profiling of MEFs transduced with either ER-MyoD wt or ER-MyoD RRR cultured in the presence of a medium that promotes skeletal muscle differentiation (DM) supplemented with beta-estradiol for 0, 6, 12, and 24 hours, respectively.
Project description:In skeletal myogenesis, the transcription factor MyoD activates distinct transcriptional programs in progenitors compared to terminally differentiated cells. Using ChIP-seq and gene expression analyses, we show that in primary myoblasts, Snail-HDAC1/2 repressive complex bind and exclude MyoD from its targets. Notably, Snail binds E-box motifs that are G/C-rich in their central dinucleotides, and such sites are almost exclusively associated with genes expressed during differentiation. By contrast, Snail does not bind the A/T-rich E-boxes associated with MyoD targets in myoblasts. Thus, Snai1-HDAC1/2 prevents MyoD occupancy on differentiation-specific regulatory elements and the change from Snail- to MyoD-binding often results in enhancer switching during differentiation. Furthermore, we show that a regulatory network involving Myogenic Regulatory Factors (MRFs), Snail/2, miR-30a and miR-206 acts as a molecular switch that controls entry into myogenic differentiation. Together, these results reveal a regulatory paradigm that directs distinct gene expression programs in progenitors versus terminally differentiated cells. This data set contains 3 replicates of a myotube growth time series (0h, 2d, 5d). The data was RMA normalized per replicate set.
Project description:In skeletal myogenesis, the transcription factor MyoD, activates distinct transcriptional programs in progenitors compared to terminally differentiated cells. Using ChIP-seq and gene expression analyses, we show that in primary myoblasts, Snai1/2-HDAC1/2 repressive complex bind and exclude MyoD from its targets. Notably, Snail binds E-box motifs that are G/C-rich in their central dinucleotides, and such sites are almost exclusively associated with genes expressed during differentiation. By contrast, Snai1/2 does not bind the A/T-rich E-boxes associated with MyoD targets in myoblasts. Thus, Snai1/2-HDAC1/2 prevents MyoD occupancy on differentiation-specific regulatory elements and the change from Snail1/2- to MyoD-binding often results in enhancer switching during differentiation. Furthermore, we show that a regulatory network involving Myogenic Regulatory Factors (MRFs), Snail/2, miR-30a and miR-206 acts as a molecular switch that controls entry into myogenic differentiation. Together, these results reveal a regulatory paradigm that directs distinct gene expression programs in progenitors versus terminally differentiated cells. In vivo depletion of transcription factor with siRNA followed by whole transcriptome analysis (RNA-seq) to identify target genes.