UCSF

Primary cilia are ubiquitous microtubule-based organelles that coordinate multiple signaling pathways critical for craniofacial development including Hedgehog, Wnt, and PDGF. Ciliary dysfunction causes a range of human disorders, collectively referred to as ciliopathies, many of which display craniofacial defects such as cleft lip/palate, micrognathia, midface dysplasia, and craniosynostosis. This dissertation explores how defects in the transition zone complex- a ciliary gatekeeper- results in a narrowing or collapse of the midface utilizing transgenic and knockout mouse models. Developmental analysis uncovered that the first molecular defects occur in the prechordal plate, a central organizing center in the developing midface. These early prechordal plate defects were transmitted to the adjacent developing forebrain resulting in a massive increase in cell death and culminating in collapse of the midface. Surprisingly, we could fully rescue the midface defects in multiple transition zone mutants by decreasing Ptch1 gene dosage. These results have uncovered the molecular underpinnings underlying craniofacial dysmorphology in a group of poorly characterized ciliopathies and hold powerful clinical implications for future strategies aimed at treatment and prevention of these defects.