Gap junctions allow communication between neighbouring cells by providing channels through which ions and small molecules can pass. In invertebrates,the junctions are built up of innexins, which are analogous to vertebrate connexins and are required for efficient electrical signal transmission. Michael Hoch and co-workers have examined the importance of gap junctions during Drosophila development by generating flies that lack innexin 2(see p. 1859). They find that the mutants display a feeding defect caused by failure of epithelial cells to migrate correctly during formation of an organ called the proventriculus. This process is part of the regionalization of the foregut tube controlled by Wingless and Hedgehog - secreted signalling molecules that direct a variety of developmental processes. The authors show genetically that Wingless regulates expression of innexin 2 in proventricular cells and demonstrate that the Wingless pathway stimulates innexin 2 expression in tissue culture. They conclude that regulation of innexin...

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