Wound-induced expression and activation of WIG, a novel glycogen synthase kinase 3

Glycogen synthase kinase 3 (GSK-3) is involved in the regulation of several physiological processes, including glycogen metabolism, protein synthesis, transcription factor activity, and developmental control. Although GSK-3-l ike genes have been isolated from plants, no function for any of these kina ses has been defined. We report here that the alfalfa wound-induced gene (W IG, for (w) under bar ound-(i) under bar nduced (G) under bar SK-3), lencod ing a functional plant GSK-3-like kinase, is activated when the alfalfa lea ves are wounded. Although WIG transcripts are hardly detectable in mature l eaves, WIG mRNA accumulates rapidly after wounding. Using a peptide antibod y that specifically recognizes p53(WIG), we show that p53(WIG) kinase is ac tivated immediately after wounding. Wound-induced activation of p53(WIG) ki nase is a post-translational process, because the concentrations of p53(WIG ) protein do not change in intact and wounded leaves, and inhibition of tra nscription or translation does not block activation by wounding. However, i nactivation of p53(WIG) kinase, which usually occurs within 60 min after wo unding, is dependent on transcription and translation of one or more protei n factors. These data suggest that the WIG kinase is involved in wound sign aling in plants.