The broad objective of this application is to understand the tissue transitions that underlie the embryonic development of the anterior eye, including the role that these transformations play in eye pathologies as well as in normal morphogenesis. The objectives of the present proposal are to decipher the molecular mechanisms that underlie transformation of epithelium to mesenchyme (EMT) and mesenchyme to epithelium (MET) and to explain the physiological mechanism used by the meesenchymal cell to invade and migrate through the matrix. Epithelium is the primitive tissue type, residing on top of extracellular matrix (ECM) as a continuous sheet of adherent cells. Creation of the mesenchymal cell adds complexity to body form, permitting the ECM between epithelia to be inhabited by inwandering cells that diversify ECM composition and migrate great distances, e.g., from neural tube to the cornea of the eye in the case of neural creast. However, inappropriate transformation of epithelium to mesenchyme in the adult can bring about abnormal ECM deposition, as in anterior capsular cataract, and devastating ECM invasion, as in malignant metastasis.
The Specific aims are to study: (1) cellular mechanisms of corneal and uveal mesenchymal cell migration into and through ECM, using the new confocal microscope to view living cells labeled with sophistcated cytoskeletal probes; we believe ours is the first study to address motility mechanisms in malignant choroid melanoma cells and that new insights will be gained about motility in metastasis; (2) molecular mechanisms of the transformation of lens to mesenchyme induced by suspension in collagen gel; this study focuses on the role of signal tranduction initiated by the protoncogene, c-src and the master mesenchymal genes thus activated in the induction of EMT; (3) induction of MET in corneal fibroblasts and choroid meanoma cells; the fibroblasts and malignant melanoma """"""""mesenchyme"""""""" will be transfected with genes for E-cadherin and/or N-Cadherin. MET inducing agents (e.g., Wnt-1 protein) are added in some cases. The results of this study could nominate cadherin-induced MET as a possible way of inhibiting uveal metastasis in vivo.
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