DEVELOPMENT OF MUSCLE-FIBER TYPES IN THE PRENATAL RAT HINDLIMB
DEVELOPMENT OF MUSCLE-FIBER TYPES IN THE PRENATAL RAT HINDLIMB
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DOI：
10.1016/0012-1606(90)90196-p
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发表时间：
1990-04-01
影响因子：
2.7
通讯作者：
THOMPSON, WJ
中科院分区：
文献类型：
--
作者：
CONDON, K;SILBERSTEIN, L;THOMPSON, WJ
采用免疫组化方法检测大鼠胚胎后肢肌纤维中肌球蛋白重链胚型、慢型和新生儿亚型的表达。虽然胚胎同种异构体在产前发育过程中存在于每一种纤维中，但到出生时，缓慢和新生儿同种异构体的表达在大多数情况下发生在单独的互补纤维群体中。慢速纤维和新生儿纤维的表达模式在单个肌肉中是高度定型的，反映了在成人中发现的慢速纤维和快纤维的分布。这种模式在肌形成的早期阶段不存在，但随着不同代纤维的加入逐渐展开。正如之前的研究者所指出的（如Narusawa et al. 1987， J. Cell Biol. 104, 447-459），所有最早的一代（原发性）肌纤维最初表达慢亚型，但其中一些原发性纤维后来失去了这种表达。在这项研究中，我们发现这些纤维中慢速肌凝蛋白的丢失伴随着新生儿肌凝蛋白的表达。这种异构体表达的转换发生在位于特定肌肉特定区域的所有初级纤维中。然而，在其他肌肉中，保留其缓慢表达的原纤维与转换为新生儿表达的原纤维广泛混合。后期生成的（次级）肌纤维，散布在初级纤维中，表达新生儿肌球蛋白，尽管其中一些固定位置的肌纤维后来从新生儿肌球蛋白表达转变为慢速肌球蛋白表达。许多观察到的肌球蛋白表达变化与轴突到达肢体或轴突侵入单个肌肉同时发生。因此，尽管纤维的出生日期和肌肉内位置都可以粗略地预测纤维的命运，但这两个因素都不足以解释大鼠后肢中纤维类型的最终模式。纤维多样化依赖于神经支配的可能性在随附的一篇论文中进行了测试。
Immunohistochemistry was used to examine the expression of embryonic, slow, and neonatal isoforms of myosin heavy chain in muscle fibers of the embryonic rat hindlimb. While the embryonic isoform is present in every fiber throughout prenatal development, by the time of birth the expression of the slow and neonatal isoforms occurs, for the most part, in separate, complementary populations of fibers. The pattern of slow and neonatal expression is highly stereotyped in individual muscles and mirrors the distribution of slow and fast fibers found in the adult. This pattern is not present at the early stages of myogenesis but unfolds gradually as different generations of fibers are added. As has been noted by previous investigators (e.g. Narusawa et al. 1987, J. Cell Biol. 104, 447-459), all of the earliest generation (primary) muscle fibers initially express the slow isoform but some of these primary fibers later lose this expression. In this study we show that loss of slow myosin in these fibers is accompanied by the expression of neonatal myosin. This switch in isoform expression occurs in all primary fibers located in specific regions of particular muscles. However, in other muscles primary fibers which retain their slow expression are extensively intermixed with those that switch to neonatal expression. Later generated (secondary) muscle fibers, which are interspersed among the primary fibers, express neonatal myosin, although a few of them in stereotyped locations later switch from neonatal to slow myosin expression. Many of the observed changes in myosin expression occur coincidentally with the arrival of axons in the limb or the invasion of axons into indivdual muscles. Thus, although both fiber birth date and intramuscular position are grossly predictive of fiber fate, neither factor is sufficient to account for the final pattern of fiber types seen in the rat hindlimb. The possibility that fiber diversification is dependent upon innervation is tested in an accompanying paper.