The transforming growth factors beta (TGFbetas) have been shown to play a critical role in the developing mammalian orofacial region. Studies in our laboratory have revealed fascinating glimpses of how TGFbeta may play a central role in integrating several important signaling cascades during craniofacial development. These insights form the basis for the pilot studies we currently propose. The myriad effects of TGFbeta support the idea that TGFbeta signaling from plasma membrane to the nucleus involves multiple pathways. Among the candidates for intracellular molecules that may act downstream of TGFbeta receptors are members of the mitogen activated protein kinase (MAPK) family. We also present sound rationale for, and propose to test the hypothesis that, a TGFbeta effect on MAPK may be due to the inhibition of a ser/threo phosphatase. In order to address the functional role that TGFbeta/MAPK signaling may play during palatal tissue differentiation we propose utilization of an antisense strategy as well as utilization of MAPK-specific inhibitors. Functional endpoints for analysis include palate medial edge epithelial (MEE) differentiation in organ culture and proliferation of murine embryonic palate mesenchymal (MEPM) cells in primary cell culture. The selection of these end points for analysis is based on the fact that they represent TGFbeta regulated biological processes integral to normal development of the embryonic palate. The current application thus proposes specific studies to test the following hypotheses: 1- Members of the MAP kinase family serve as downstream vehicles for TGFbeta signaling; 2- TGFbeta- induced palate medial edge epithelial differentiation and/or inhibition of mesenchymal cell proliferation may be mediated via down-regulation of the ERK/MAPK cascade.
