Wiping the cellular slate clean

A dose of the JNK kinase can reset chromatin states and turn leg into wing, according to Nara Lee, Renato Paro (University of Heidelberg, Germany), and colleagues. The pathway may help cells to become reprogrammable when they find themselves in areas of injury or developmental transition.JNK has for some time been known to turn on during wound healing, and Polycomb group (PcG) proteins are known to maintain cell fates by clamping down on chromatin. But the two have never been united in one experimental design.

The Heidelberg team took a look at the two processes in fly imaginal discs—the embryonic tissues that will eventually turn into adult structures such as legs. A fraction of the leg imaginal discs are known to transdetermine—or change to a wing cell fate—when they are transplanted and wounded. In the new experiments,...