Djhsp60 Is Required for Planarian Regeneration and Homeostasis

Abstract

HSP60, a well-known mitochondrial chaperone, is essential for mitochondrial homeostasis. HSP60 deficiency causes dysfunction of the mitochondria and is lethal to animal survival. Here, we used freshwater planarian as a model system to investigate and uncover the roles of HSP60 in tissue regeneration and homeostasis. HSP60 protein is present in all types of cells in planarians, but it is relatively rich in stem cells and head neural cells. Knockdown of HSP60 by RNAi causes head regression and the loss of regenerating abilities, which is related to decrease in mitotic cells and inhibition of stem cell-related genes. RNAi- HSP60 disrupts the structure of the mitochondria and inhibits the mitochondrial-related genes, which mainly occur in intestinal tissues. RNAi- HSP60 also damages the integrity of intestinal tissues and downregulates intestine-expressed genes. More interestingly, RNAi- HSP60 upregulates the expression of the cathepsin L-like gene, which may be the reason for head regression and necrotic-like cell death. Taking these points together, we propose a model illustrating the relationship between neoblasts and intestinal cells, and also highlight the essential role of the intestinal system in planarian regeneration and tissue homeostasis.

Differentially expressed chaperone genes reveal a stress response required for unidirectional regeneration in the basal chordate Ciona

“…A similar result was obtained when apoptosis, which occurs on the proximal side of distal wounds [ 6 ], was suppressed by caspase inhibitors [ 7 ]. The role of the HSP70 chaperone system in progenitor cell migration and not stem cell proliferation has also been reported in planaria [ 48 ], and HSP70 and the HSP40 family member MRJ are known to regulate cell migration in tumor cells [ 49 ]. In Ciona , our results imply that the activation of stem cell proliferation may be independent of the HSP70 chaperone system expressed in the BS.…”