Meeting Abstract
Hox genes are a set of highly conserved homeobox transcription factors that pattern the anterior posterior axis in bilaterally symmetrical animals. This conserved developmental function is known as the “Hox code” and is important for axial patterning in all bilaterian lineages. Hox genes are also found in cnidarians, the sister group to the bilateria that includes corals, anemones and jellyfish. This distinction has made cnidarian model systems crucially important for the study of Hox gene evolution. To define the developmental function of the cnidarian Hox cluster, we have performed CRISPR Cas9 mediated knockouts of individual Hox genes in the model sea anemone, Nematostella vectensis. Functional analysis of F0 mutants indicates that Cnidarian Hox genes are required for the formation of both the primary and directive axes during early development. Three Hox genes, Anthox1, Anthox6 and Anthox6a, appear to be important for the formation of the primary axis and are asymmetrically expressed along this axis at early developmental stages. To investigate their functional role at this stage we are assessing changes in spatial and temporal gene expression of important asymmetrically expressed markers in knockout animals. Preliminary data suggests that Hox gene function along the primary axis is dependent on novel regulatory relationships with components of the Wnt signaling pathway, which has been proposed as the primary axial patterning mechanism in Cnidarians. Further, we have adopted a forward approach (CEL-SEQ) for identifying downstream targets of Cnidarian Hox genes at important developmental stages. We are working to develop a detailed understanding of the Hox gene repertoire in Cnidarians and hope that this study will provide new insights into Hox gene evolution and the origins of the Hox code.
