The regulation of rapamycin in planarian Dugesia japonica Ichikawa & Kawakatsu, 1964 regeneration according to TOR signaling pathway

The freshwater planarian mostly lives in the upper reaches of springs and rivers. Generally, it is realized as a suitable warning indicator of environmental toxicants. The freshwater planarian Dugesia japonica has a powerful regenerative capability and can regenerate a new individual including a complete central nervous system in one week. Rapamycin is an inhibitor of mammalian TORC1 (target of rapamycin complex-1) and used in the treatment of some diseases like cancer, cardiovascular and neurological diseases. However, the roles of rapamycin in the regulation of planarian regeneration remain to be elucidated. In present study, freshwater planarians D. japonica were firstly treated with 1 μM rapamycin for 18 h exposures and the expression patterns of Djtor was analyzed by the whole-mount in situ hybridization (WISH). Our results indicated rapamycin could strongly inhibit Djtor expression in planarian D. japonica and cause asymmetric blastemas and neuronal defects in planarians. Furthermore, knockdown of Djtor gene in planarians using RNA interference resulted in the suppression of downstream autophagy genes. These findings suggested that rapamycin might regulate freshwater planarian regeneration via Djtor signaling pathway. •Rapamycin can enter the environment with human excretion when it is overdosed or overtaken, polluting our soil and water.•The planarian Dugesia japonica is considered as an emerging animal model for toxicology studies.•Rapamycin can strongly inhibit Djtor expression; caused asymmetric blastemas and neuronal defects in D. japonica regeneration.•Knockdown of Djtor gene in D. japonica resulted in the suppression of downstream autophagy genes.•Rapamycin might regulate freshwater planarian regeneration via Djtor signaling pathway.