Hedgehog signals gut growth Available to Purchase

Vertebrate digestive tract development requires hedgehog (Hh) signalling, but the exact mechanisms by which Hh regulates gut development are not known. Andrew McMahon, Junhao Mao and colleagues now report, on p. 1721, that Hh signalling is required for the proliferation of mesenchymal progenitor cells in the developing mouse gut. By conditionally inactivating the expression of sonic hedgehog (Shh) and Indian hedgehog (Ihh) in the early gut endoderm, the authors observed a decrease in the size of the digestive tract and a reduction in the development of the mesenchyme compared with controls. Through a combination of in vivo and in vitro experiments, they showed that Hh proteins act as mitogens required for the proliferation of mesenchymal progenitors in the mouse embryo, including those progenitors that develop into gut smooth muscle cells. Based on their results, the researchers propose that a similar mechanism might be involved in postnatal gut homeostasis. In...