Expression of p53 Homologue in Early Blastema and Its Role in Regeneration of Planarian Dugesia japonica

To study the expression pattern and function of the planarian Dugesia japonica p53 homologue(Djp53),whole-mount in situ hybridization(WISH) with digoxigenin-labeled RNA probes and RT-PCR were used.The results showed that Djp53 was strongly expressed in the blastema at 1,3,5 days during regeneration after amputation with a peak level at day 3.Reduced expression was detected throughout the parenchyma of intact adult and regenerated tissues at day 7 and 10,with a spatial localization to the stem cells.When Djp53 was silenced by RNAi,significantly decreased expression was observed in intact planarians.Djp53 depleted planarians failed the normal regeneration and exerted a rough eye phenotype at day 15 after amputation.Our results suggested that Djp53 was essential for planarian regeneration and effected blastema formation at early stages,as well as in regulating neoblasts migration,proliferation and differentiation,which were required for stem cell maintenance at late stages of regeneration or adult development of planrian.