Meighan-Mantha R L, Hausman R E, Tolan D R
Boston University, Department of Biology, Massachusetts 02215, USA.
Exp Cell Res. 1995 Sep;220(1):55-61. doi: 10.1006/excr.1995.1291.
Expression of several muscle-specific genes was monitored during chicken muscle development and myoblast differentiation in primary cultures. The individual patterns of expression for many muscle-specific genes are well documented in ovo and in other model systems of muscle development. However, comparison of aldolase A to other muscle-specific genes in one system has not been reported. Both sarcomeric and cytosolic genes important for the adult muscle fiber were examined in order to elucidate their timing of expression and its relationship to cell fusion. Steady-state mRNA expression was measured using RNase protection assays with cRNA probes generated from cDNA clones for muscle creatine kinase, fast skeletal troponin-T, embryonic myosin heavy chain, and aldolase A. Nonmuscle genes expressed largely in the embryo, aldolase C and beta-actin, were used as controls. The expression of all six genes revealed differences in temporal expression patterns between limb and axial muscle. The temporal expression patterns of all six genes were also monitored in primary myoblast cultures relative to myoblast fusion. In both axial and limb myoblast cultures most of the muscle-specific genes were expressed prior to fusion. During the differentiation of myoblasts to myotubes there was a biphasic pattern in the expression of the muscle-specific genes. The appearance of measurable mRNA was detected by 16 hr in culture, prior to appreciable fusion of the cells. During further differentiation the expression increased gradually and then more rapidly at 96 hr, once fusion was complete. Meanwhile, the nonmuscle embryonic gene expression declined only slightly. For one gene, aldolase A, expression was delayed relative to the other muscle-specific genes, both in the appearance of measurable mRNA and in the later rapid increase in mRNA.
在鸡肌肉发育以及原代培养的成肌细胞分化过程中，对几种肌肉特异性基因的表达进行了监测。许多肌肉特异性基因的个体表达模式在胚胎内以及其他肌肉发育模型系统中都有充分记录。然而，尚未有在一个系统中将醛缩酶A与其他肌肉特异性基因进行比较的报道。为了阐明它们的表达时间及其与细胞融合的关系，研究了对成年肌纤维重要的肌节和胞质基因。使用核糖核酸酶保护分析，通过从肌肉肌酸激酶、快肌型肌钙蛋白-T、胚胎肌球蛋白重链和醛缩酶A的cDNA克隆产生的cRNA探针来测量稳态mRNA表达。主要在胚胎中表达的非肌肉基因醛缩酶C和β-肌动蛋白用作对照。所有六个基因的表达显示肢体和轴肌之间在时间表达模式上存在差异。相对于成肌细胞融合，还在原代成肌细胞培养物中监测了所有六个基因的时间表达模式。在轴和成肌细胞培养物中，大多数肌肉特异性基因在融合之前就已表达。在成肌细胞向肌管分化过程中，肌肉特异性基因的表达呈双相模式。在培养16小时时，在细胞明显融合之前就检测到了可测量的mRNA的出现。在进一步分化过程中，表达逐渐增加，然后在96小时时，一旦融合完成，表达增加得更快。与此同时，非肌肉胚胎基因的表达仅略有下降。对于一个基因醛缩酶A，其表达相对于其他肌肉特异性基因有所延迟，无论是在可测量mRNA的出现方面，还是在随后mRNA的快速增加方面。
