The long-term objectives of this proposal are to elucidate the role of epigenetic regulation of gene expression during mammalian orofacial development. Formation of the mammalian orofacial tissue is a multifaceted, synchronized developmental process involving cell migration, proliferation, differentiation, apoptosis, and synthesis of extracellular matrix. All these critical cellular processes are under the control of a variety of genes encoding growth and differentiation factors, signaling mediators, transcription factors and extracellular matrix proteins, whose expression is controlled, in turn, by epigenetically-modulated regulatory elements. Disruption of any one of these processes can lead to orofacial clefting. Emerging evidence strongly supports the importance of epigenetic mechanisms controlling the expression of key genes critical for orofacial ontogenesis. Recent studies from our lab have demonstrated that precise patterns of differential gene methylation and expression occur in embryonic orofacial tissue. Preliminary data revealed several epigenetically regulated genes which have documented critical roles in orofacial morphogenesis. We thus propose to test the hypothesis that regulation of differentially-expressed genes via differentially methylated regions, is essential for proper development of the embryonic orofacial region. Three hypothesis-driven specific aims will be pursued: 1) Differentially expressed genes encoding mRNAs are epigenetically regulated during orofacial development. 2) Differentially expressed and epigenetically regulated gene transcripts are essential for the regulation of specific biological processes as well as phenotypic outcomes associated with orofacial development, and 3) Selected differentially-expressed target genes are epigenetically regulated via differentially methylated regions during orofacial development.