Expression And Function Analysis Of DjRhoA Gene From Planarian Dujesia Japonica

The Rho-family proteins make up a major branch of the Ras superfamily of small GTPases, and the RhoA is one of the best known'classical'members of Rho-family, RhoA function as molecular switch, cycling between active GTP-bound and inactive GDP-bound states to mediate intracellular signal transduction pathways in response to extracellular stimuli. Numerous studies have revealed RhoA performed essential functions in a variety of biological processes, including cytoskeletal regulation, cell cycle progression and gene transcription. Planarians are an ideal model system to study in vivo the dynamics of adult pluripotent stem cells and all aspects of regeneration. However, our knowledge of the factors involved in maintenance and regulation of neoblasts is sparse. To investigate the certain function of RhoA in planarian Dugesia japonica, experimental techniques whole-mount in situ hybridization (WISH), immunohistochemistry and RNA interference (RNAi) were applied.WISH showed during embryonic development DjRhoA was expressed in embryonic pharynx, germ band, the pioneer nerve cells, and it was expressed in blastmas during regeneration. DjRhoA dsRNA-mediated knockdown resulted in a severe proliferative failure of the neoblasts and ectopic formation of the brain. These results suggested that DjRhoA was required for nervous system maintenance and planarian stem cell proliferation.Together our results suggest that DjRhoA is required in stem cell progeny as they form the regenerative blastema and is required for the maintenance of the central nervous system. Further studies are needed to unravel the molecular pathways involved in these processes.