Unknown,Transcriptomics,Genomics,Proteomics

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Comparison of Genome-Wide Binding of MyoD in Normal Human Myogenic Cells and Rhabdomyosarcomas Identifies Regional and Local Suppression of Promyogenic Transcription Factors (expression profiling).

ABSTRACT: Rhabdomyosarcoma is a pediatric tumor of skeletal muscle that expresses the myogenic basic helix-loop-helix protein MyoD but fails to undergo terminal differentiation. Prior work has determined that DNA binding by MyoD occurs in the tumor cells, but myogenic targets fail to activate. Using MyoD chromatin immunoprecipitation coupled to high-throughput sequencing and gene expression analysis in both primary human muscle cells and RD rhabdomyosarcoma cells, we demonstrate that MyoD binds in a similar genome-wide pattern in both tumor and normal cells but binds poorly at a subset of myogenic genes that fail to activate in the tumor cells. Binding differences are found both across genomic regions and locally at specific sites that are associated with binding motifs for RUNX1, MEF2C, JDP2, and NFIC. These factors are expressed at lower levels in RD cells than muscle cells and rescue myogenesis when expressed in RD cells. MEF2C is located in a genomic region that exhibits poor MyoD binding in RD cells, whereas JDP2 exhibits local DNA hypermethylation in its promoter in both RD cells and primary tumor samples. These results demonstrate that regional and local silencing of differentiation factors contributes to the differentiation defect in rhabdomyosarcomas. ChIP-Seq profiling of MyoD in human myotube, myoblast and rhabdomyosarcoma cells

ORGANISM(S): Homo sapiens

SUBMITTER: Zizhen yao

PROVIDER: E-GEOD-50413 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background: Similar to replicating myoblasts, many rhabdomyosarcoma cells express the myogenic determination gene MyoD. In contrast to myoblasts, rhabdomyosarcoma cells do not make the transition from a regulative growth phase to terminal differentiation. Previously we demonstrated that the forced expression of MyoD with its E-protein dimerization partner was sufficient to induce differentiation and suppress multiple growth-promoting genes, suggesting that the dimer was targeting a switch that regulated the transition from growth to differentiation. Our data also suggested that a balance existed between various inhibitory transcription factors and MyoD activity that kept rhabdomyosarcomas trapped in a proliferative state. Methods: Potential myogenic co-factors identified by analysis of high-throughput sequencing of chromatin immunoprecipitation experiments in normal myogenic cells were tested for their ability to drive differentiation in rhabdomyosarcoma cell culture models, and their relation to MyoD activity determined through molecular biological experiments. Results: Modulation of the transcription factors RUNX1 and ZNF238, factors with poorly delineated roles in myogenic development, can induce differentiation in rhabdomyosarcoma cells and their activity is integrated, at least in part, through the activation of miR-206, which acts as a genetic switch to transition the cell from a proliferative growth phase to differentiation. The inhibitory transcription factor MSC also plays a role in controlling miR-206, appearing to function by occluding a binding site for MyoD in the miR-206 promoter. Conclusions: These findings suggest that nested feed-forward circuits that proceed from MyoD, to RUNX1, to ZNF238, and finally to miR-206 function in both rhabdomyosarcomas as well as normal myogenesis to control the decision point of proliferation versus differentiation. Total RNA samples were collected from human RD cells transduced with lentivirus carrying RUNX1, RP58 (ZNF238), miR-206 or GFP (three biological replicates each) and allowed to differentiate for 72 hours.

Project description:Background: Similar to replicating myoblasts, many rhabdomyosarcoma cells express the myogenic determination gene MyoD. In contrast to myoblasts, rhabdomyosarcoma cells do not make the transition from a regulative growth phase to terminal differentiation. Previously we demonstrated that the forced expression of MyoD with its E-protein dimerization partner was sufficient to induce differentiation and suppress multiple growth-promoting genes, suggesting that the dimer was targeting a switch that regulated the transition from growth to differentiation. Our data also suggested that a balance existed between various inhibitory transcription factors and MyoD activity that kept rhabdomyosarcomas trapped in a proliferative state. Methods: Potential myogenic co-factors identified by analysis of high-throughput sequencing of chromatin immunoprecipitation experiments in normal myogenic cells were tested for their ability to drive differentiation in rhabdomyosarcoma cell culture models, and their relation to MyoD activity determined through molecular biological experiments. Results: Modulation of the transcription factors RUNX1 and ZNF238, factors with poorly delineated roles in myogenic development, can induce differentiation in rhabdomyosarcoma cells and their activity is integrated, at least in part, through the activation of miR-206, which acts as a genetic switch to transition the cell from a proliferative growth phase to differentiation. The inhibitory transcription factor MSC also plays a role in controlling miR-206, appearing to function by occluding a binding site for MyoD in the miR-206 promoter. Conclusions: These findings suggest that nested feed-forward circuits that proceed from MyoD, to RUNX1, to ZNF238, and finally to miR-206 function in both rhabdomyosarcomas as well as normal myogenesis to control the decision point of proliferation versus differentiation. Two biologically independent sets of RD cells were transduced with either MD~E or empty vector pCLBabe retroviruses. After RNA extraction pairs of samples (MD~E versus pCLBabe) were hybridized to arrays, incorporating both dye-swap and technical replicates (i.e. 1 comparison x 2 dye-swaps x 2 biological replicates x 2 technical replicates = 8 arrays)

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Comparison of Genome-Wide Binding of MyoD in Normal Human Myogenic Cells and Rhabdomyosarcomas Identifies Regional and Local Suppression of Promyogenic Transcription Factors (expression profiling).

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