|Budget Amount *help
¥1,500,000 (Direct Cost : ¥1,500,000)
Fiscal Year 1991 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1990 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Summary. Recently the mesoderm-inducinig effects of the transforming growth factor beta (TGF-beta)family, of proteins have been widely examined. In an attaint to elucidate the functions of these proteins, porcine inhibin A and activin A(erythroid differentiation factor ; EDF)were examined. Treatment of explants with activin A led to differentiation of mesodermal derivatives such as mesenchyme, notochord, blood cells and muscle, but inhibin A had a much lesser effect. The niesodernial differentiation induced by activin A was also comfirmed by analyses using a polyclonal antibody against muscle myosin. By indirect immufluorescence analysis, the differentiation of muscle blocks was observed in the activin-Atreated explants, whereas no differentiation was observed in inhibin-A-treated and control explants. These findings confirm that this protein of the TGF-beta family, has mesoderm-inducing ability.
Activin A, a member of the transforming growth factor beta superremily, has recently been f
ound to have potent mesoderm-inducing activity on isolated early Xenopus animal-cap cells. We measured the activin activity of the Xenopus egg extract by using an erythroid-differentiating test with Friend leukemia cells. The results showed that an activin homologue is, indeed, contained in unfertilized eggs and blastulae of Xenopus laevis in a considerable amount. This activity was eluted at the same retention time as human activin A when fraction2ted by reversed-phase HPLC. Furthermore, the fraction containing erythroid-differentiating factor activity had mesoderm-inducing activity on Xenopus animal-cap cells. The mesoderm-inducing activity of this traction was suppressed when coincubated with follistatin, an activin-binding protein. These results suggest that an endogenous activin may be a natural mesoderm-inducing factor acting In Xenopus embryogenesis.
The induction of mesoderm is an important process in early amphibian development. In recent studies, activin has become an effective candidate for a natural mesoderm-inducing factor. In the present study, we show that follistatin, an activin-binding protcin puriFied from porcine ovary, inhibits the mesoderm-inducing activity of recombinant human activin A(rh activin A). which is identical to the crythroid differentiation factor(EDF). The quantity of follistatin required for effective suppression of activin was more than three-fold that of activin(w : w). Follistatin also inhibited the mesoderminducing activity of the vegetalizing factor purified from chick embryos, suggesting that the vegetalizing factor is closely related to activin. Less