During craniofacial morphogenesis, neural crest cells migrate from the dorsal aspect of the cranial neural tube and infiltrate extensive regions of the developing head and neck, where they differentiate into a spectrum of cellular phenotypes. As they migrate, cranial neural crest cells invade extensive cell-free spaces, containing glycosaminoglycans, fibronectin, and collagen, as well as other glycoconjugates. Transplantation experiments have shown that this extracellular environment influences neural crest cell migration and differentiation. Experiments described in this proposal will examine the migration, division, and morphology of cranial neural crest cells in vitro on a host of glycoconjugate substrates, including glycosaminoglycans, fibronectin, and collagen. We will also examine cranial neural crest cell behavior on endogenously synthesized glycoconjugates and on """"""""feeder"""""""" layers of neural crest cells. These analyses will use time lapse cinematography as well as light and scanning electron microscopy. We will also determine whether cell surface glycosyltransferases participate in neural crest migration by binding to, and glycosylating substrate glycoconjugates. Experiments will use exogenously added sugar nucleotides, as well as endogenous sugar donors synthesized by neural crest cells. The glycosylated residue will be extracted and characterized from all glycoconjugate substrates. Specific glycosyltransferase inhibitors will test the instructive or incidental role of surface glycosyltransferases in cranial neural crest cell migration. The proposed experiments will shed light on a fundamental aspect of craniofacial morphogenesis.
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