Role of MAP kinase in mesoderm induction and axial patterning during Xenopus development

C. LaBonne, B. Burke, M. Whitman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

157 Scopus citations


We have examined the role of MAP kinase during mesoderm induction and axial patterning in Xenopus embryos. MAP Kinase Phosphatase (MKP-1) was used to inactivate endogenous MAP kinase and was found to prevent the induction of early and late mesodermal markers by both FGF and activin. In whole embryos, MKP-1 was found to disrupt posterior axial patterning, generating a phenotype similar to that obtained with a dominant inhibitory FGF receptor. Overexpression of either constitutively active MAP kinase or constitutively active MAP kinase (MEK) was sufficient to induce Xbra expression, while only constitutively active MEK was able to significantly induce expression of muscle actin. When MAP kinase phosphorylation was used as a sensitive marker of FGF receptor activity in vivo, this activity was found to persist at a low and relatively uniform level throughout blastula stage embryos. The finding that a low level of MAP kinase phosphorylation exists in unstimulated animal caps and is absent in caps overexpressing a dominant inhibitory FGF receptor provides a basis for our previous observation that overexpression of this receptor inhibits activin induction. These results indicate that FGF-dependent MAP kinase activity plays a critical role in establishing the responsiveness of embryonic tissues to mesoderm inducers.

Original languageEnglish (US)
Pages (from-to)1475-1486
Number of pages12
Issue number5
StatePublished - Jan 1 1995


  • Activin
  • MAP kinase
  • Mesoderm induction
  • Signal transduction
  • Xenopus

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology


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