TWIST1 direct targets during embryonic stem cell differentiation

Twist1 encodes a basic helix-loop-helix (bHLH) transcription factor and is a key regulator of craniofacial development. Mutations of TWIST1 gene in human are associated with Saethre-Chotzen syndrome (SCS), a developmental disorder characterized by facial and skull malformations, which are phenocopied by Twist1-null heterozygous mice. Mechanisms that dictate the tissue-specificity of Twist1 in regulating distinct transcriptional targets in different craniofacial cell types remain to be determined. Our work using mass-spectrometry and co-expression analysis in cell lines and embryonic head tissues has revealed that the most prevalent forms of TWIST1 were homodimers and heterodimers with E-proteins (TCF3,TCF4 and TCF12). RNA-seq analysis of embryoid bodies expressing tethered TWIST-E-protein dimers, and ChIP-seq profiling of TWIST1 genome-wide binding sites revealed mechanisms of TWIST1 functional regulation. This study highlighted the pleiotropic roles of TWIST1 dimers in development and revealed a potential molecular mechanism underpinning Twist1-related developmental defects of craniofacial tissues. Refer to individual Series