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Stowers Institute
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Craniofacial Development
Understanding the mechanisms that control head and facial development is an important problem, as one-third of all human congenital birth defects exhibit craniofacial abnormalities. Neural crest cells are a migratory cell population born early during embryonic development, which ultimately generates much of the bone, cartilage, connective tissue, and peripheral nervous system of the head and face. Craniofacial abnormalities are therefore largely attributed to defects in the formation, proliferation, migration and differentiation of neural crest cells. Classical models for craniofacial development suggested that the cell fate and genetic identity of the neural crest is programmed prior to its migration from the neural tube.
Recently, however, we demonstrated that cranial neural crest cells in mouse embryos are plastic and their development can be influenced by the tissues they interact with during migration. Thus, congenital craniofacial malformations can arise either through intrinsic or extrinsic defects in neural crest development. In the lab, we are currently investigating whether intrinsic neural crest cell defects are responsible for Treacher Collins Syndrome craniofacial abnormalities.
We have also undertaken gene discovery approaches (ENU mutagenesis and microarray) to identify new genes involved in craniofacial development and neurogenesis and we are focusing in particular on the interactions between the cranial mesoderm and neural crest.
Treacher Collins Syndrome
Treacher Collins Syndrome (OMIM number 154500) is an autosomal dominant craniofacial disorder that occurs as the result of mutations in the TCOF1 gene, which encodes the nucleolar protein Treacle 1. With an incidence of one in 50,000 Treacher Collins Syndrome is characterized by numerous developmental anomalies such as small jaws, cleft palate and middle and external ear defects. The majority of the facial structures affected in Treacher Collins Syndrome are derived either in part or in their entirety from cranial neural crest cells. We are currently investigating the role of Tcof1 in neural crest cell development as a mechanism for understanding the origins of this particular birth defect as well as possible avenues for prevention and repair.
ENU Mutagenesis
Mutagenesis of mice with the chemical mutagen, ethylnitrosourea (ENU) is an efficient technique for generating and identifying mouse models that mimic specific human disease processes. In the lab we have undertaken a small scale ENU mutagenesis screen aimed at identifying novel genes involved in craniofacial development. We are currently characterizing 10 recessive mutations which exhibit holoprosencephaly, brain and open neural tube defects, cleft palate and hypoplastic branchial arch and limb development. Possible gene candidates have been identified in the retinoid and sonic hedgehog signaling pathways.
Cranial Mesoderm
The cranial mesoderm predominantly generates the vasculature and musculature in the head but also forms part of bony skull vault and base of the skull. Previously, we demonstrated that the cranial mesoderm can influence neural crest cell migration and patterning. From a microarray screen we have identified a large number of mesoderm specific genes that may play key roles in craniofacial development. In particular we are examining the roles played by members of the Vefg, Igf and Fox gene families in regulating the interactions between cranial mesoderm and neural crest cells.
Academic Appointment: Assistant Professor, Department of Anatomy & Cell Biology, The University of Kansas School of Medicine |
