Expression of Growth Factor Genes in the Body Wall of the Holothurian <i>Eupentacta fraudatrix</i> During Regenerative Processes

Research into regeneration in sea cucumbers makes a significant contribution to understanding the fundamental mechanisms of this process. However, these studies focus only on the regenerating organs-the intestine and aquapharyngeal bulb. The source of cells for regeneration remains out of sight. The cells of the body wall, under the influence of various activating molecules (growth factors), dedifferentiate, determine the direction of migration, and move toward the injury. Therefore, the aim of this study was to identify the most active growth factor genes in the body wall during the regenerative process in the sea cucumber Eupentacta fraudatrix. We searched for and identified genes of the TGF-β, FGF, Neurotrophin, VEGF families. The sea cucumber Eupentacta fraudatrix possesses a set of growth factor genes characteristic of all echinoderms, with the exception of three orthologs of gdf2 genes. A significant increase in the expression of gdf2, bmp2/4, neurotrophin, and wnt5 genes was detected in the body wall as early as the first day of the regenerative process. A second increase in growth factor gene expression occurred on day 7, during the onset of the proliferation and growth phase. The results of this study identify the most promising genes for further investigation of their role in the signal transduction that triggers regeneration.