Hopwood N D, Gurdon J B
Cancer Research Campaign Molecular Embryology Group, Department of Zoology, Cambridge, UK.
Nature. 1990 Sep 13;347(6289):197-200. doi: 10.1038/347197a0.
The sequence-specific DNA-binding protein, MyoD, can activate muscle-specific gene expression in some cells in culture. Xenopus MyoD (XMyoD) transcription is activated as a consequence of mesoderm induction in the early myotomes, from which the axial musculature develops. XMyoD RNA accumulates about two hours before muscle-specific actin transcripts first appear, and so is expressed at the right time and in the right place to play a part in activating muscle-specific gene expression in normal development. To test this idea, we have expressed XMyoD ectopically in early Xenopus embryos. We find that injection of XMyoD RNA can strongly activate muscle genes in embryo cells normally destined to form ectoderm. Nevertheless, these cells fail to differentiate as muscle, suggesting that additional factors are required for complete and stable myogenesis.
序列特异性DNA结合蛋白MyoD能够在培养的某些细胞中激活肌肉特异性基因的表达。非洲爪蟾MyoD（XMyoD）转录是早期肌节中胚层诱导的结果，轴向肌肉组织由此发育而来。XMyoD RNA在肌肉特异性肌动蛋白转录本首次出现前约两小时积累，因此在正常发育过程中，它在正确的时间和位置表达，从而在激活肌肉特异性基因表达中发挥作用。为了验证这一想法，我们在非洲爪蟾早期胚胎中异位表达了XMyoD。我们发现，注射XMyoD RNA能够强烈激活正常情况下注定形成外胚层的胚胎细胞中的肌肉基因。然而，这些细胞无法分化为肌肉，这表明完全稳定的肌生成还需要其他因素。
