Zhang J M, Chen L, Krause M, Fire A, Paterson B M
Laboratory of Biochemistry, NCI, National Institutes of Health, Bethesda, Maryland, 20892, USA.
Dev Biol. 1999 Apr 15;208(2):465-72. doi: 10.1006/dbio.1999.9218.
The formation of striated muscle in both vertebrates and invertebrates involves the activity of the MyoD family of basic-helix-loop-helix (bHLH) transcription factors. The high degree of evolutionary conservation of MyoD-related proteins, both in the sequence of their bHLH domains and in their general developmental expression patterns, suggests that these factors are also conserved at the level of function. We have addressed this directly using MyoD and E protein factors from vertebrates, Drosophila, and Caenorhabditis elegans. Various MyoD and E factor combinations were tested for their ability to interact in vitro and to function in vivo in the myogenic conversion of 10T12 mouse fibroblasts. We found that the ability of different homo- and heterodimers to bind DNA in vitro was an accurate measure of biological activity in vivo. A second assessment of conserved function comes from the ability of these factors to rescue a C. elegans hlh-1 (CeMyoD) null mutation. We found that both Drosophila and chicken MyoD-related factors were able to rescue a C. elegans CeMyoD loss-of-function mutation. These results demonstrate a remarkable degree of functional conservation of these myogenic factors despite differences in E-protein interactions.
脊椎动物和无脊椎动物横纹肌的形成都涉及碱性螺旋-环-螺旋（bHLH）转录因子的MyoD家族的活性。MyoD相关蛋白在其bHLH结构域序列及其一般发育表达模式方面具有高度的进化保守性，这表明这些因子在功能水平上也具有保守性。我们直接使用来自脊椎动物、果蝇和秀丽隐杆线虫的MyoD和E蛋白因子来解决这个问题。测试了各种MyoD和E因子组合在体外相互作用以及在10T12小鼠成纤维细胞的肌源性转化中在体内发挥功能的能力。我们发现不同的同二聚体和异二聚体在体外结合DNA的能力是体内生物活性的准确衡量指标。对保守功能的第二项评估来自这些因子挽救秀丽隐杆线虫hlh-1（CeMyoD）无效突变的能力。我们发现果蝇和鸡的MyoD相关因子都能够挽救秀丽隐杆线虫CeMyoD功能丧失突变。这些结果表明，尽管E蛋白相互作用存在差异，但这些肌源性因子在功能上具有显著程度的保守性。
