Mesoderm induction in Xenopus laevis distinguishes between the various TGF-beta isoforms

Growth Factors. 1990;3(4):277-86. doi: 10.3109/08977199009003670.


Induction of mesoderm in ectodermal explants of Xenopus laevis blastula embryos had previously been shown to respond selectively to TGF-beta 2, with TGF-beta s 1 and 5 having no activity in this assay. As TGF-beta s 1, 2, and 3 are frequently coexpressed in tissues, we wished to examine the activity of TGF-beta 3 relative to that of TGF-beta s 1 and 2 in this assay as well as in other in vitro assays. We report here that when the activity of recombinant TGF-beta 3 is normalized to that of TGF-beta 1 in the assay for growth inhibition in CCL-64 cells, it is also equal to that of TGF-beta 1 in assays for stimulation of both anchorage-independent growth of rat NRK cells and chemotaxis of human monocytes. In contrast, in the assay for mesoderm induction, recombinant TGF-beta 3 is 10-fold more active than TGF-beta 2, inducing expression of muscle specific alpha-actin at concentrations as low as 1 ng/ml. These results suggest that more complex systems, in contrast to individual cell types, may respond selectively to the various TGF-beta isoforms and that there might be biological consequences of TGF-beta isoform switching in vivo.

MeSH terms

  • Animals
  • Base Sequence
  • Blastocyst / drug effects
  • Blastocyst / physiology*
  • Cell Division / drug effects
  • Embryo, Nonmammalian / physiology
  • Growth Substances / pharmacology
  • Mesoderm / drug effects
  • Mesoderm / physiology*
  • Molecular Sequence Data
  • Plasmids
  • Restriction Mapping
  • Structure-Activity Relationship
  • Transforming Growth Factor beta / genetics
  • Transforming Growth Factor beta / pharmacology*
  • Xenopus laevis


  • Growth Substances
  • Transforming Growth Factor beta