An axial Hox code controls tissue segmentation and body patterning in <i>Nematostella vectensis</i>

Hox code in segmentation and patterning Hox genes encode conserved transcription factors that are best known for their role in governing anterior-posterior body patterning in diverse bilaterian animals. He et al. used a combination of CRISPR mutagenesis and short hairpin RNA–based gene knockdowns to interrogate Hox gene function in a cnidarian, the sea anemone Nematostella vectensis (see the Perspective by Arendt). Four homeobox-containing genes constitute a molecular network that coordinately controls the morphogenesis of radial endodermal segments and the patterning of tentacles. Thus, an ancient Hox code may have evolved to regulate both tissue segmentation and body patterning in the bilaterian-cnidarian common ancestor. Science , this issue p. 1377 ; see also p. 1310