Hedgehog (Hh) proteins – membrane-associated signals involved in many developmental processes – can elicit signalling responses at considerable distances away from the cells that secrete them, and the transmembrane protein Dispatched (Disp) plays a key role in this journey. Tian and colleagues (p. 4021) now investigate the function of mammalian Disp1 during embryogenesis, and shed light on the mode of Disp action. Using mice with a hypomorphic Disp1 allele, the researchers found that Disp1 has a dose-dependent effect on the severity of Hh-dependent phenotypes, such as those affecting facial morphology, and ventral forebrain, telencephalon and neural tube patterning. Furthermore, as Disp1 levels are reduced, ventral cell identities in the neural tube are progressively lost, while increasing Hh levels restores ventral cell types. The researchers conclude that Disp1 regulates the levels of Hh protein available in the target tissue, and they discuss several possible mechanisms of Disp action during...

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