Characterization of hsp genes in planarian stem cells

Planarians are a model system known for regenerative potential, body plasticity and continuous turnover of all differentiated cell types. These characteristics are based on the presence of pluripotent stem cells, called neoblasts. Damage or reduction in the number of neoblasts deeply affects planarian regeneration and survival. Heat shock proteins (HSPs) are known to perform essential cytoprotective functions in all organisms. To investigate the potential role of hsp-related genes on the dynamics of planarian stem cells, representative hsp-related genes were identified and characterized in normal conditions and after different stress stimuli. Our work revealed that two different hsp genes (Djhsp60 and Djmot) are constitutively expressed in neoblasts, suggesting that their products play important roles in cytoprotection of these cells. RNAi-based functional studies provide evidence of an involvement of Djhsp60 and Djmot in the adaptive response of planarian stem cells to stress and indicate that expression of these genes is critical for planarian survival.