Manipulations of PKA in chick limb development reveal roles in digit patterning including a positive role in Sonic Hedgehog signaling

Eva Tiecke, Roisin Turner, Juan Jose Sanz-Ezquerro, Anne Warner, Cheryll Tickle

    Research output: Contribution to journalArticlepeer-review

    28 Citations (Scopus)


    Sonic Hedgehog (Shh) signaling by the polarizing region, at the posterior of the vertebrate limb bud, is pivotal in determining digit number and identity. Shh establishes a gradient of the bifunctional transcriptional effector, Gli3, with high levels of full-length activator (Gli3A) in the posterior bud, where digits form, and high levels of shorter repressor (Gli3R) in the anterior. Repressor formation depends on protein kinase A (PKA), but in Drosophila, PKA also plays a role in activator function. Increasing PKA levels in chick limb development using Forskolin had no effect on posterior polarizing activity but weak polarizing activity, based on ligand-independent Shh signaling, was induced in anterior limb bud cells resulting in extra digits. Manipulating PKA activity levels directly with a retrovirus expressing activated PKA induced extra digits similar to those induced by Forskolin treatment suggesting that PKA may have a previously unrecognized positive role in Shh signaling in vertebrate limbs. Expressing dominant negative PKA also induced extra, sometimes multiple digits, from anterior limb bud demonstrating the negative role in Shh signaling. PKA levels in the limb bud are high posteriorly and low anteriorly, suggesting that PKA activity may influence the outcome of Shh signaling in normal development.
    Original languageEnglish
    Pages (from-to)312-324
    Number of pages13
    JournalDevelopmental Biology
    Issue number1
    Publication statusPublished - 2007


    • Animals
    • Blotting, Western
    • Body Patterning
    • Chick Embryo
    • Colforsin
    • Cyclic AMP-Dependent Protein Kinases
    • DNA Primers
    • Forelimb
    • Gene Expression Regulation, Developmental
    • Hedgehog Proteins
    • In Situ Hybridization
    • Reverse Transcriptase Polymerase Chain Reaction
    • Signal Transduction


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