Molecular Characterization of the Stress Response of the Holothurian Central Nervous System

Abstract

Injury to the central nervous system (CNS), in most vertebrate animals, results in permanent damage and lack of function, due to their limited regenerative capacities. In contrast, echinoderms can fully regenerate their radial nerve cord (RNC) following transection, with little or no scarring. Investigators have associated the regenerative capacity of some organisms with the stress response and inflammation produced by the injury. Here we explore the gene activation profile of the stressed holothurian CNS. To do this, we performed RNA sequencing on isolated RNC explants submitted to the stress of transection and enzyme dissection and compared them to explants kept in culture for 3 days following dissection. We describe stress-associated genes, including members of heat-shock families, ubiquitin-related pathways, transposons, and apoptosis that were differentially expressed. Surprisingly, the stress response does not induce apoptosis in this system. Other genes associated with stress in other animal models, such as hero proteins and those associated with the integrated stress response, were not found to be differentially expressed either. Our results provide a new viewpoint on the stress response in the nervous system of an organism with an amazing regenerative capacity. This is the first step to deciphering the molecular processes that allow echinoderms to undergo fully functional CNS regeneration while also providing a comparative view for students of the stress response in other organisms.