Polycomb group (PcG) chromatin proteins regulate homeotic genes in both animals and plants. In Drosophila and vertebrates, PcG proteins form complexes and maintain early patterns of Hox gene repression, ensuring fidelity of developmental patterning. PcG proteins in C. elegans form a complex and mediate transcriptional silencing in the germline, but no role for the C. elegans PcG homologs in somatic Hox gene regulation has been demonstrated. Surprisingly, we find that the PcG homologs MES-2 [E(Z)] and MES-6 (ESC), along with MES-3, a protein without known homologs, do repress Hox expression in C. elegans. mes mutations cause anteroposterior transformations and disrupt Hox-dependent neuroblast migration. Thus, as in Drosophila, vertebrates, and plants, C. elegans PcG proteins regulate key developmental patterning genes to establish positional identity.
Bibliographical noteFunding Information:
We thank Julie Ahringer, Scott Emmons, Rik Korswagen, and Susan Strome for strains and reagents and Vivian Bardwell, Weiru Chang, Kara Thoemke, Susan Strome, and members of the Strome lab for critical reading of the manuscript. We thank Susan Strome, Jeffrey Simon, and members of the Zarkower lab and the University of Minnesota Center for Developmental Biology for many helpful discussions and Scott Emmons for sharing results prior to publication. Some strains used in this work were provided by the C. elegans Genetics Center, which is funded by the NIH-NCRR. J.M.R. is supported by a University of Minnesota Graduate School Fellowship. This work was supported by a grant from the NIH (GM53099) to D.Z.