Project description:The TEAD (1-4) transcription factors comprise the conserved TEA/ATTS DNA binding domain recognising the MCAT element in the promoters of muscle-specific genes. Despite extensive genetic analysis, the function of TEAD factors in muscle differentiation has proved elusive due to redundancy amongst the family members. Expression of the TEA/ATTS DNA binding domain that acts a dominant negative repressor of TEAD factors in C2C12 myoblasts inhibits their differentiation, while selective shRNA knockdown of TEAD4 results in abnormal differentiation characterised by the formation of shortened myotubes. Chromatin immunoprecipitation coupled to array hybridisation (ChIP-chip) shows that TEAD4 occupies 867 promoters including those of myogenic miRNAs. We show that TEAD factors cooperate with MYOD1 to directly induce Myogenin, CDKN1A and Caveolin 3 expression to promote myoblast differentiation and fusion. RNA-seq identifies a novel set of TEAD4 target genes encoding muscle structural and regulatory proteins and those required for the unfolded protein response. In contrast, TEAD4 represses expression of the growth factor CTGF and Cyclin D1 to promote differentiation. Together these results show that TEAD factor activity is essential for C2C12 cell differentiation and define a novel and nonredundant role for TEAD4 in regulating the unfolded protein response. C2C12 cells were infected with retrotiviral vector expressing Flag-HA-Tagged TEAD4 or with empty control vector and selected in the continouos presence of puromycin. Infected cell populations were then differentiated for 5 days in DMEM medium with 2% horse serum and fixed in 0.4% formaldehyde.
Project description:Defining the function of TEAD transcription factors in myogenic differentiation has proved elusive due to overlapping expression and functional redundancy. Here, we show that siRNA silencing of either Tead1, Tead2 or Tead4 did not effect differentiation of primary myoblasts (PMs) while their simultaneous knockdown strongly impaired differentiation. In contrast in C2C12 cells, silencing of Tead1 or Tead4 impaired differentiation showing a differential requirement for these factors in PMs and C2C12 cells that involved both differential regulation of their expression and intracellular localisation. Through integration of Tead1 and Tead4 ChIP-seq with chromatin modifications, we identify active enhancers associated with genes activated during C2C12 cell differentiation that are bound by combinations of Tead4, Myod1 or Myog and show a signature of frequently co-occuring motifs. We show that distinct but overlapping sets of genes are deregulated by Tead silencing in C2C12 cells and PMs therefore describing for the first time in a comprehensive manner the specific and redundant regulatory roles of Tead factors in myogenic differentiation. We also performed ChIP-seq from mouse muscle in vivo identifying a set of highly transcribed muscle cell-identity genes and revealing that Tead4 binds a distinct repertoire of sites in C2C12 cells and muscle.
Project description:Defining the function of TEAD transcription factors in myogenic differentiation has proved elusive due to overlapping expression and functional redundancy. Here, we show that siRNA silencing of either Tead1, Tead2 or Tead4 did not effect differentiation of primary myoblasts (PMs) while their simultaneous knockdown strongly impaired differentiation. In contrast in C2C12 cells, silencing of Tead1 or Tead4 impaired differentiation showing a differential requirement for these factors in PMs and C2C12 cells that involved both differential regulation of their expression and intracellular localisation. Through integration of Tead1 and Tead4 ChIP-seq with chromatin modifications, we identify active enhancers associated with genes activated during C2C12 cell differentiation that are bound by combinations of Tead4, Myod1 or Myog and show a signature of frequently co-occuring motifs. We show that distinct but overlapping sets of genes are deregulated by Tead silencing in C2C12 cells and PMs therefore describing for the first time in a comprehensive manner the specific and redundant regulatory roles of Tead factors in myogenic differentiation. We also performed ChIP-seq from mouse muscle in vivo identifying a set of highly transcribed muscle cell-identity genes and revealing that Tead4 binds a distinct repertoire of sites in C2C12 cells and muscle.