Inhibition of Protein Kinase A Phenocopies Ectopic Expression ofhedgehogin the CNS of Wild-Type andcyclopsMutant Embryos

AbstractThe zebrafishhedgehog(hh) family memberstiggy-winkle hedgehog(twhh) andsonic hedgehog(shh) are involved in patterning the ventral CNS and proximal eye. Using a dominant negative protein kinase A regulatory subunit mutant, we show that these hh activities are mediated by protein kinase A. The effects of dominant negative protein kinase A onpax2expression appear to be cell nonautonomous, suggesting that cells can respond to regulation of hh signaling by modulating an additional cell–cell signaling pathway. We also investigate the potential involvement ofcyclopsin the hh signaling pathway and conclude that althoughcyclopsmutant cells can respond to hh signaling, neither hh nor dominant negative protein kinase A rescues the phenotypes associated withcyclops