Evolutionary conservation of the chromatin modulator Polycomb in the jellyfish Podocoryne carnea

Abstract

Polycomb-group (PcG) proteins form chromatin-associated multimeric complexes, which are responsible for the maintenance of the transcriptionally repressive state of regulatory genes during development. We have isolated a Polycomb homologue of the hydrozoan Podocoryne carnea by a PCR-based approach. Our results demonstrate that structure and function of Polycomb-group proteins have been conserved in evolution from cnidarians to vertebrates since Podocoryne Polycomb interacts in yeast with mouse dinG/RING1B, an interaction partner of the mouse Polycomb homologue MPc3. Polycomb is expressed throughout the life cycle of Podocoryne. In situ hybridization reveals a differential expression pattern in proliferating and differentiating tissues of the developing medusa bud. In the transdifferentiation of activated isolated striated muscle of the medusa to smooth muscle and RFamide–positive nerve cells, Polycomb expression is strongly increased when differentiation into nerve cells occurs.