Regulation of cranial neural crest cell fate by Irf6 and Twist1 interaction

Abstract

A wide variety of common craniofacial birth defects and pediatric cancers arise from errors in the development of cranial neural crest cells (CNCC) that give rise to craniofacial skeletal and peripheral nervous systems. Identification of the genetic and environmental factors that regulate cell fate of CNCCs is crucial for uncovering the causes behind craniofacial disorders. Our lab has identified a dual‐transcription factor pathway that regulates CNCCs during EMT and migration. Initially, we identified a causative mutation in a TWIST1 binding site within an Interferon Regulatory Factor 6 (IRF6) enhancer in a multi‐generational family affected with syndromic cleft lip and palate called Van der Woude syndrome. Our subsequent animal work has shown that Twist1 and Irf6 genetically interact during early craniofacial development, and that the compound heterozygotes exhibit craniofacial abnormalities. We recently demonstrated that Irf6 is required for neural tube and CNCC development and that it interacts with Twist1 during EMT and migration of CNCCs. We also showed that TWIST1 is highly phosphorylated in CNCCs and its phosphorylation is crucial for regulating Irf6 and potentially miR10 family members in CNCC‐derived craniofacial tissues. Our recent in‐vivo and neural tube explants using dual fluorescent cell tracing system showed that Twist1 conditional knockout (CKO) in CNCCs significantly reduced cell delamination and disrupted EMT. The detached Twist1 CKO in CNCCs retained their epithelial signatures and migrated as clusters of epithelial‐like cells over significantly shorter distances. Finally, Twist1 phospho‐incompetent mice for two serine residues were recently generated to determine their impact on TWIST1 activity. Our preliminary results showed that Twist1S68A/S68A phospho‐mutant mice have craniofacial bone defects and forebrain hemorrhage. Support or Funding Information UTHealth start‐up funds and a small grant from theRolanette and Berdon Lawrence Bone Disease Program of Texas