Machinery and Developmental Role of Retinoic Acid Signaling in Echinoderms

Abstract

Although a recent genomic survey revealed its ancient evolutionary origin in the animal kingdom, retinoic acid (RA) signaling was previously thought to be unique to chordates. Echino-derms are of critical interest in researching the evolutionary history of RA signaling, as they repre-sent a basal group of deuterostomes. Furthermore, our previous works have suggested that echino-derms may possess the ancestral function of RA signaling for metamorphosis regulation. In this paper, to facilitate future studies of RA signaling in echinoderms, we provide an overview of RA machinery in echinoderms, identify its signaling components, and discuss its developmental role.