Meeting Abstract
Gene regulatory networks (GRNs) consisting of functional linkages between regulatory genes and their cis-regulatory modules determine the development of animal body plans. Given the hierarchical nature of organ development that starts with the specification of a field of cells followed by the patterning of its morphological features and terminal differentiation, the GRNs regulating these processes are also hierarchical. Thus, subcircuits regulating early specification, referred to as “kernels” of the GRN have more pleiotropic effects and are evolutionarily constrained compared to subcircuits responsible for subsequent fine-scale patterning and terminal differentiation. Studies of heart development in bilaterians have led to the identification of an evolutionarily conserved hierarchical GRN, consisting of interconnections between upstream signaling pathways that direct cardiac cell fate, myogenic transcription factors and their downstream target genes. To better understand the evolutionary origins of the heart specification GRN, we looked at the regulation and function of components of the bilaterian heart GRN in the anthozoan cnidarian, Nematostella. Morpholino mediated knock down of NvBMP 2/4, a key upstream regulator of the bilaterian heart-field specification kernel, resulted in the down regulation of NvNkx2-like, NvHAND2 and NvGATA in developing gastrodermis, all components of the bilaterian heart GRN kernel. This indicates to the presence of an ancestral heart-field specification kernel in the endomesdoerm of the non-bilaterian Nematostella. Targeted functional experiments focused on these components and their downstream targets will provide a detailed understanding of the heart GRN kernel in Nematostella and the origins of heart development in metazoans.
