Limb regrowth takes two

Abstract

Salamanders can regenerate several of their organs, including amputated limbs. Analysis of a Mexican salamander shows that crosstalk between two signalling molecules regulates limb regeneration. See Letter p.407 Some features of salamander limb regeneration following amputation have puzzled developmental biologists for years. Although experimental grafting shows that juxtaposition of anterior and posterior limb, as well as innervation, are sufficient to induce the formation of a limb, the mechanism involved has been a mystery. Elly Tanaka and colleagues have now identified fibroblast growth factor 8 (FGF8) as a key anterior signal, acting in concert with posteriorly localized sonic hedgehog (SHH) signalling to drive non-regenerating tissue into forming a full limb.