Transcription profiling of human rhabdomyosarcoma cells expressing Myod and E-protein heterodimer and controls
Ontology highlight
ABSTRACT: Rhabdomyosarcomas (RMS) are characterized by expression of myogenic specification genes, such as MyoD and/or Myf5, as well as their bHLH partners for heterodimerization, the E-proteins. We have shown that expression of a forced heterodimer of MyoD with one of the E2A proteins, E12, leads to differentiation in a RMS cell culture model when exposed to low serum conditions. Experiment Overall Design: RD cells (a type of RMS) were retrovirally infected with either the MyoD~E heterodimer or an empty control vector, differentiated for 24 hours and then RNA collected.
Project description:Rhabdomyosarcomas (RMS) are characterized by expression of myogenic specification genes, such as MyoD and/or Myf5, as well as their bHLH partners for heterodimerization, the E-proteins. We have shown that expression of a forced heterodimer of MyoD with one of the E2A proteins, E12, leads to differentiation in a RMS cell culture model when exposed to low serum conditions. Keywords: RD expressing Myod~E heterodimers and controls
Project description:Rhabdomyosarcoma (RMS) is a frequent non-epithelial tumor of soft tissue that originates from a myogenic differentiation defect. Expression of SNAIL transcription factor is elevated in the alveolar subtype of RMS, characterized by a low myogenic differentiation status and high aggressiveness. SNAIL affects RMS metastasis by reorganization of actin cytoskeleton, regulation of ezrin expression and chemotaxis to HGF and SDF-1. The differentiation of human RMS diminishes SNAIL level. SNAIL silencing completely abolishes the growth of human RMS xenotransplants. SNAIL inhibits myogenic differentiation of RMS by binding to the MYF5 promoter, suppressing its expression, displacing MYOD from canonical to alternative E-box sequences and regulating myomiRs expression. SNAIL silencing allows the re-expression of MYF5 and canonical MYOD binding, promoting RMS cell myogenic differentiation. These novel results open potential avenues for the development of innovative therapeutic strategies based on SNAIL silencing.
Project description:Many pediatric malignancies are embryonal in nature, and one hypothesis for the origin of embryonal tumors is that they arise from a defect in differentiation, either by an inability to terminally differentiate or a reversion to a pluripotent state. There is emerging evidence that epigenetic regulation plays an important role in the transition from embryonic stem cell to a more committed cell fate, utilizing both de novo DNA methylation and poised M-bM-^@M-^XbivalentM-bM-^@M-^Y chromatin domains (H3K27me3 and H3K4me3) to abolish pluripotency and gain lineage- and cell-type-specific characteristics as a cell differentiates. Thus inappropriate epigenetic silencing by aberrant DNA methylation of bivalent genes required for differentiation could lead to the uncontrolled cell growth observed in cancer. Our broad hypothesis is that aberrant DNA methylation in cancer is targeted to a non-random subset of critical pathways used in normal development. This dysregulation of the normal epigenetic program used in development promotes cellular proliferation and provides a mechanism to block differentiation in pediatric cancers, such as rhabdomyosarcoma. Examination of DNA methylation in fourteen human rhabdomyosarcoma patient samples using RRBS. In addition, RRBS was used to examine DNA methylation in one human rhabdomyosarcoma cell line (RD) forced to terminally differentiate by expression of the forced heterodimer MyoD~E12 (MDE). Lastly, RRBS was used to examine DNA methylation changes during normal differentiation in one primary human normal myoblast cell line
Project description:In this work we compare the molecular functions of Myf5 and MyoD, two highly related bHLH transcription factors that regulate skeletal muscle specification and differentiation. We find MyoD and Myf5 bind the same sites genome-wide but have distinct functions: Myf5 induces histone acetylation without Pol II recruitment or robust gene activation, whereas MyoD induces histone acetylation, recruits PolII and robustly activates gene transcription. Chip-seq profiling of MyoD, Myf5, Histone H4 acetylation (H4Ac), and Pol II in MyoD-/-; Myf5-/- MEFs (M&M MEFs)
Project description: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
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)
Project description:In this work we compare the molecular functions of Myf5 and MyoD, two highly related bHLH transcription factors that regulate skeletal muscle specification and differentiation. We find MyoD and Myf5 bind the same sites genome-wide but have distinct functions: Myf5 induces histone acetylation without Pol II recruitment or robust gene activation, whereas MyoD induces histone acetylation, recruits PolII and robustly activates gene transcription. RNA-Seq profiling of MyoD and Myf5
Project description:In this work we compare the molecular functions of Myf5 and MyoD, two highly related bHLH transcription factors that regulate skeletal muscle specification and differentiation. We find MyoD and Myf5 bind the same sites genome-wide but have distinct functions: Myf5 induces histone acetylation without Pol II recruitment or robust gene activation, whereas MyoD induces histone acetylation, recruits PolII and robustly activates gene transcription.
Project description:In this work we compare the molecular functions of Myf5 and MyoD, two highly related bHLH transcription factors that regulate skeletal muscle specification and differentiation. We find MyoD and Myf5 bind the same sites genome-wide but have distinct functions: Myf5 induces histone acetylation without Pol II recruitment or robust gene activation, whereas MyoD induces histone acetylation, recruits PolII and robustly activates gene transcription.