PUCKERED ENCODES A PHOSPHATASE THAT MEDIATES A FEEDBACK LOOP REGULATING JNK ACTIVITY DURING DORSAL CLOSURE IN DROSOPHILA

The activation of MAPKs is controlled by the balance between MAPK kina se and MAPK phosphatase activities. The latter is mediated by a subset of phosphatases with dual specificity (VH-1 family). Here, we describ e a new member of this family encoded by the puckered gene of Drosophi la. Mutations in this gene lead to cytoskeletal defects that result in a failure in dorsal closure related to those associated with mutation s in basket, the Drosophila INK homolog. We show that puckered mutatio ns result in the hyperactivation of DJNK, and that overexpression of p uc mimics basket mutant phenotypes. We also show that puckered express ion is itself a consequence of the activity of the JNK pathway and tha t during dorsal closure, JNK signaling has a dual role: to activate an effector, encoded by decapentaplegic, and an element of negative feed back regulation encoded by puckered.