TLE EXPRESSION CORRELATES WITH MOUSE EMBRYONIC SEGMENTATION, NEUROGENESIS, AND EPITHELIAL DETERMINATION

The TLE proteins are the mammalian homologues of Groucho, a member of the Drosophila Notch signaling pathway. Notch signaling controls the d ifferentiation of a variety of tissues in invertebrates and vertebrate s. We are investigating the role of the TLE genes during mammalian dev elopment. We show that TLE I and TLE 3 are expressed during a number o f cell-determination events, including embryonic segmentation, central and peripheral neurogenesis, and epithelial differentiation. This exp ression pattern is in agreement with the involvement of Groucho in sim ilar fate choices in Drosophila and suggests that Groucho and TLE prot eins perform similar developmental roles. Our results also show that T LE genes are co-expressed during a variety of cell-fate choices with s everal vertebrate homologues of genes implicated in the Drosophila Not ch cascade, suggesting a role for the TLE proteins in mammalian Notch signaling.