Characterization of gli2/2b genes in zebrafish hindbrain development

Abstract

Gli are key mediators of Hedgehog signaling on regulating neurodevelopment in vertebrates. Previously, zebrafish Gli2 was characterized playing minor role in neurodevelopment, in contrast to the major role of mouse Gli2. In this study, second zebrafish gli2 (gli2b) was identified. Late regulation of gli2b expression depends on Hh and Notch signaling. Comparative analysis of the function of Gli2/Gli2b demonstrates their major roles as the Hedgehog-dependent activators for ventral neurodifferentiation, and the Hh-independent repressors for maintenance of dorsal neural progenitors. This study also demonstrates the joint activities of Gli2/Gli2b for several neural cell types and axonal guidance. Further, this study indicates that Gli2 dominant repressor of yot-/- doesnot interfere with all spectra of Gli2b functions, especially in rhomomere 4. In summary, this study helps to explain the functional differences of Gli2 between zebrafish and mice, and illustrate unknown developmental roles of Gli2 useful for the studies in other animals including human.