Evolutionary analysis and functional characterization of the forkhead transcription factor FoxG1

Includes bibliographical references (leaves 103-110).Forhead box G1 (FoxG1) is a winged-helix transcription factor that plays a crucial role in the development of the telecephalon, the most rostral region of the brain Here, FoxG1 acts as a transcriptional repressor and maintains the population of cortical progenitor cells by promoting their proliferation and inhibiting differrentiation. Vertebrate FoxG1 orthologs have highly conserved DNA-binding and corbosy-terminal domains that have functional roles. Conversely, no functional role has yet been assigned to the N-terminal domain which shows a high degree of variability across vertebrates, with a remarkable stretch of consecutive histidine, proline and glutamine (HPQ) residues in the mammalian orthologs. In this study it was tested whether differences in FoxG1 sequence amongst vertebrates might account for the increased cortex size of mammals compared to non-mammals. Furthermore, changes in the sub-cellular localization of FoxG1 in response to fibroblast growth factor 2 (FGF-2) were investigated in a neural precursor cell line