Biemar, F., Baraldi, F., Devos, N., Holzschuh, J., Martial, J.A., Driever, W., and Peers, B. (2002) Analysis of meis genes expression in zebrafish suggests a role in the development of organs derived from the endoderm. Developmental Biology. 247(2):495.
Hox genes encode homeodomain-containing transcription factors that function to establish body organization along the anterior–posterior axis in arthropods and vertebrates. Members of the TALE superclass of homeodomain proteins (i.e., Pbx/Exd and Meis/Hth) have been shown to act as cofactors of Hox protein function. By forming dimeric and trimeric complexes with Hox proteins in vitro, these partners provide enhanced DNA-binding affinity and specificity to the otherwise not very fussy Hox monomers. Pdx-1, another homeodomain protein whose gene does not lie on the hox gene clusters, has also been shown to interact with Pbx/Exd and/or Meis/Hth cofactors. Pdx-1 is essential for pancreas development during embryogenesis and for pancreas-specific gene expression in adulthood. We showed previously that Pdx-1 synergizes with Pbx1a and Prep1 on the UE-A element of the somatostatin promoter. Using the zebrafish as a model, we are employing a combination of gain and loss of function approaches to address the possible role of such trimers in the patterning of the endoderm and/or the development of endodermally derived organs. We have identified several members of the meis/prep family in zebrafish and studied their expression pattern during the embryonic development. We show that meis3 is expressed specifically in a subset of endodermal cells during somitogenesis. Recent progress of our functional study will be presented.