Cell signaling and transcription factor genes expressed during whole body regeneration in a colonial chordate

To elucidate mechanisms underlying this phenomenon, a subtracted EST library for early WBR stages was previously assembled, revealing 76 putative genes belonging to major signaling pathways, including Notch/Delta, JAK/STAT, protein kinases, nuclear receptors, Ras oncogene family members, G-Protein coupled receptor (GPCR) and transforming growth factor beta (TGF-β) signaling. RT-PCR on selected transcripts documented specific up-regulation in only regenerating fragments, pointing to a broad activation of these signaling pathways at onset of WBR. The followed-up expression pattern of seven representative transcripts from JAK/STAT signaling (Bl-STAT), the Ras oncogene family (Bl-Rap1A, Bl-Rab-33), the protein kinase family (Bl-Mnk), Bl-Cnot, Bl-Slit and Bl-Bax inhibitor, revealed systemic and site specific activations during WBR in a sub-population of circulatory cells.WBR in the non-vertebrate chordate Botrylloides leachi is a multifaceted phenomenon, presided by a complex array of cell signaling and transcription factors. Above results, provide a first insight into the whole genome molecular machinery of this unique regeneration process, and reveal the broad participation of cell signaling and transcription factors in the process. While regeneration involves the participation of specific cell populations, WBR signals are systemically expressed at the organism level.Whereas most animal phyla share the capability to repair damaged tissues and some organs, whole body reconstitution from small fragments is a rare event in deuterostomes and is mostly confined to protostomes like sponges [1], cnidarians [2] and flatworms [3]. An exception is the dramatic botryllid ascidians phenomenon of whole-body regeneration (WBR) from minute vasculature fragments [4-8], best studied in B. leachi. As the capacity for wide-range regeneration is limited in chordates [9], WBR may be used as a model system for studying the restricted regeneration ability and the basic mechanisms underlying