The correct development and functioning of the spinal cord depends on the patterning, proliferation and differentiation of neural progenitor cell cohorts along the dorsoventral axis of the neural tube. But how are the numbers of these cells controlled? On p. , Stuart Wilson and colleagues demonstrate that the cadherin FatJ acts via the Hippo pathway to regulate the size of neural progenitor pools in the chick neural tube. Using a large-scale RNAi screen of all cadherin genes expressed in the neural tube, the researchers identified a role for FatJ in neural tube patterning. FatJ, they report, is expressed in intermediate regions of the neural tube, and a loss of FatJ leads to an increase in the size of the progenitor pool in this region. This effect is mediated via the Hippo pathway component Yap1. Thus, this first report of a large-scale RNAi screen in a whole vertebrate organism reveals an important role for FatJ in controlling the proliferation and differentiation of specific interneuron classes.
