Ventrolateral regionalization of Xenopus laevis mesoderm is characterized by the expression of α-smooth muscle actin

J. P. Saint-Jeannet, G. Levi, J. M. Girault, V. Koteliansky, J. P. Thiery

Research output: Contribution to journalArticlepeer-review


Mesodermal patterning in the amphibian embryo has been extensively studied in its dorsal aspects, whereas little is known regarding its ventrolateral regionalization due to a lack of specific molecular markers for derivatives of this type of mesoderm. Since smooth muscles (SM) are thought to arise from lateral plate mesoderm, we have analyzed the expression of an α-actin isoform specific for SM with regard to mesoderm patterning. Using an antibody directed against α-SM actin that recognized specifically this actin isoform in Xeiwpus, we have found that the expression of α-SM actin is restricted to visceral and vascular SM with a transient expression in the heart. The overall expression of the α-SM actin appears restricted to the ventral aspects of the differentiating embryo. α-SM actin expression appears to be activated following mesoderm induction in animal cap derivatives. Moreover, at the gastrula stage, SM precursor cells are regionalized since they will only differentiate from ventrolateral marginal zone explants. Using the animal cap assay, we have found that α-SM actin expression is specifically induced in treated animal cap with bFGF or a low concentration of XTC-MIF, which induce ventral structures, but not with a high concentration of XTC-MIF, which induces dorsal structures. Altogether, these results establish that α-SM actin is a reliable marker for ventrolateral mesoderm. We discuss the importance of this novel marker in studying mesoderm regionalization.

Original languageEnglish (US)
Pages (from-to)1165-1173
Number of pages9
Issue number4
StatePublished - Aug 1992


  • Actin
  • Amphibian
  • Growth factors
  • Induction
  • Mesoderm
  • Smooth muscle

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology


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