Identification of Novel Binding Partners for Transcription Factor Emx2.

The mammalian homolog of Drosophila empty spiracles 2 (Emx2) is a homeobox transcription factor that plays central roles in early development of the inner ear, pelvic and shoulder girdles, cerebral cortex, and urogenital organs. The role for Emx2 is best understood within the context of the development of the neocortical region of the cortex, where Emx2 is expressed in a high posterior-medial to low anterior-lateral gradient that regulates the partitioning of the neocortex into different functional fields that perform discrete computational tasks. Despite several lines of evidence demonstrating an Emx2 concentration-dependent mechanism for establishing functional areas within the developing neocortex, little is known about how Emx2 physically carries out this role. Although several binding partners for Emx2 have been identified (including Sp8, eIF4E, and Pbx1), no screens have been used to identify potential protein binding partners for this protein. We utilized a yeast two-hybrid screen using a library constructed from embryonic mouse cDNA in an attempt to identify novel binding partners for Emx2. This initial screen isolated two potential Emx2-binding partner proteins, Cnot6l and QkI-7. These novel Emx2-binding proteins are involved in multiple levels of mRNA metabolism that including splicing, mRNA export, translation, and destruction, thus making them interesting targets for further study.