Leg formation and regeneration

In contrast to higher vertebrates, orthopteran nymphs have remarkable regenerative capacity for regrowing complex morphological structures and organs. In this review, we summarize the molecular basis of tissue regeneration in the cricket Gryllus bimaculatus. In this species, the lost part of a leg can be regenerated epimorphically from blastema cells, a population of dedifferentiated proliferating cells. Blastema cell proliferation is regulated by JAK/STAT and Salvador/Warts/Hippo signaling pathways. The positional information for leg regrowth, which includes the recognition of amputated position and proper regeneration, is maintained by Dachsous/Fat signaling. The regrowth of lost leg segments is reconstructed through the expressions of genes in the hedgehog, wingless, decapentaplegic, and Egf signaling pathways and epigenetic modifiers E(z) and Utx. The insights obtained reveal the high level of conservation between insects and vertebrates, suggesting that Gryllus may be a suitable model for human regenerative medicine studies.