Mesoderm induction and gene expression by activin A (=EDF)

摘要近年来，转化生长因子β（TGF-β）家族蛋白质的中胚层诱导作用已被广泛研究。为了阐明这些蛋白质的功能，对猪红细胞毒素A和激活素A（红细胞分化因子; EDF）进行了检测。用激活素A处理外植体导致中胚层衍生物如间充质、脊索、血细胞和肌肉的分化，但白蛋白A的作用要小得多。用抗肌球蛋白的多克隆抗体进行分析，证实了激活素A诱导的尼氏分化。通过间接免疫荧光分析，在激活素A处理的外植体中观察到肌肉块的分化，而在阿糖胞苷A处理的外植体和对照外植体中没有观察到分化。这些发现证实了这种TGF-β家族的蛋白质具有中胚层诱导能力。激活素A是转化生长因子β超家族的一员，最近已经被证实具有诱导中胚层分化的能力。 关于我们 在分离的早期非洲爪蟾动物帽细胞上具有有效的中胚层诱导活性。我们通过使用Friend白血病细胞的红系分化试验测量了爪蟾卵提取物的激活素活性。结果表明，激活素同源物，确实，包含在非洲爪蟾的未受精卵和囊胚在相当大的量。当通过反相HPLC分级分离时，该活性在与人激活素A相同的保留时间洗脱。此外，含有红系分化因子活性的组分对爪蟾动物帽细胞具有中胚层诱导活性。当与卵泡抑素（一种激活素结合蛋白）共孵育时，这种牵引的中胚层诱导活性被抑制。这些结果表明，内源激活素可能是一种天然的中胚层诱导因子，在爪蟾胚胎发生中起作用，中胚层的诱导是两栖动物早期发育的重要过程。在最近的研究中，激活素已成为天然中胚层诱导因子的有效候选者。在本研究中，我们证明了卵泡抑素，一种从猪卵巢中纯化的激活素结合蛋白，抑制重组人激活素A（rh激活素A）的中胚层诱导活性。其与crysthroid分化因子（EDF）相同。有效抑制激活素所需的卵泡抑素的量是激活素的三倍以上（w：w）。卵泡抑素还抑制从鸡胚中纯化的植物化因子的中胚层诱导活性，表明植物化因子与激活素密切相关。少

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 … More 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