Abstract
The retinoblastoma (RB) gene is a tumor suppressor gene that plays an important role in cell cycle arrest and in the terminal differentiation of skeletal myoblasts. Differentiation into muscle occurs in Xenopus embryo explants during mesoderm induction by fibroblast growth factor (FGF) or activin A. We examined expression of the RB gene product (pRB) during mesoderm induction in vivo and in vitro. We show that hypo- and hyper-phosphorylated forms of pRB are present during early development and that expression of both forms increases significantly during the blastula stage, concomitant with mesoderm induction. Further investigation revealed that pRB is enriched in the presumptive mesoderm of the blastula stage embryo. In animal cap explants induced by Xenopus bFGF (XbFGF), pRB expression levels increased approximately tenfold while no increase was observed in explants induced by activin. However, when explants were induced by XbFGF in the presence of sodium orthovanadate, a compound previously shown to synergize with FGF to produce more dorsal ”activin-like” inductions than FGF alone, only a slight increase in pRB expression was observed. Furthermore, upregulation of pRB during mesoderm induction in vitro displayed an inverse correlation with expression of XFKH1, a marker for notochord. These results suggest that pRB may be important for patterning along the dorsoventral axis.
Similar content being viewed by others
Author information
Authors and Affiliations
Additional information
Received: 22 February 1996 / Accepted: 20 September 1996
Rights and permissions
About this article
Cite this article
Greenland, J., Gillespie, L. Regulated expression of the retinoblastoma gene product by fibroblast growth factor but not by activin during mesoderm induction in Xenopus . Dev Gene Evol 206, 333–336 (1996). https://doi.org/10.1007/s004270050060
Issue Date:
DOI: https://doi.org/10.1007/s004270050060