LAUSR

between transcription factors and protein partners. For the BioID analysis, TWIST1 was fused to the BirA* biotin ligase that will biotinylate TWIST1 interacting proteins in the native condition and a cellular environment. The biotinylated proteins were then captured by streptavidin beads and processed for mass-spectrometry identification. Bioinformatics analysis of the proteomic data from three cell lines and cross comparison with public datasets revealed both known and potentially novel interacting partners of TWIST1. Followup network analysis of the TWIST1 interactome identified interaction hubs featuring transcription factors and chromatin modifiers. Mutations of many of these interacting partners are associated with human syndromes that share the phenotypic overlap with SaethreChotzen Syndrome (linked to TWIST1 mutations) in the craniofacial region. We further mapped the gene regulatory network of TWIST1 and its partners through the analysis of our transcriptome data on TWIST1 downstream genes in the craniofacial tissues, and our and public ChIP-seq datasets of TWIST1 and the interacting partner in other cell models. Currently we are generating, using the CRISPR technology, embryos from double heterozygote knock-out embryonic stem cells to assess the role of the TWIST1-protein complexes in craniofacial development.