Shimizu N, Shimada Y
Dev Biol. 1985 Oct;111(2):324-34. doi: 10.1016/0012-1606(85)90487-7.
Using monoclonal antibodies (McAbs) which can distinguish between breast- and leg-type troponin T (TnT), we studied the spatial distribution of TnT isoforms in adult chicken fast skeletal muscles. The breast (pectoralis major) and leg (iliotibialis posterior) muscles were composed predominantly of homogeneous fibers containing breast- and leg-type TnT, respectively. The posterior latissimus dorsi muscle was composed of heterogeneous fibers of at least two types, namely breast and leg types. In developing and regenerating fast muscles, only leg-type TnT was expressed at early stages, and later breast-type TnT appeared either transiently or permanently. This led ultimately to several distinct adult fast muscle breast/leg TnT isoform profiles. Since both types of TnT were synthesized in embryonic and regenerating muscles with nerves intact as well as in regenerating muscles with nerves resected, the switching on of their expression during fast muscle development appears to be independent of nerves. However, its full development ("fine tuning" of the protein isoform distribution within the fast fiber types) and the maintenance of the adult state are presumed to be dependent on the nerves, since, although regenerating fibers in denervated muscles could exhibit the early and then the later embryonic stainabilities, they again returned to the early embryonic state; further, the denervation of adult muscles caused the replacement of TnT isoform from the adult to the early embryonic state.
利用能够区分乳腺型和腿部型肌钙蛋白T（TnT）的单克隆抗体（McAbs），我们研究了成年鸡快速骨骼肌中TnT同工型的空间分布。胸肌（胸大肌）和腿部肌肉（胫后肌）主要分别由含有乳腺型和腿部型TnT的同质纤维组成。背阔肌后部由至少两种类型的异质纤维组成，即乳腺型和腿部型。在发育和再生的快速肌肉中，早期仅表达腿部型TnT，随后乳腺型TnT短暂或永久出现。这最终导致了几种不同的成年快速肌肉乳腺/腿部TnT同工型分布。由于两种类型的TnT在胚胎和神经完整的再生肌肉以及神经切除的再生肌肉中均有合成，因此在快速肌肉发育过程中它们表达的开启似乎与神经无关。然而，其充分发育（快速纤维类型内蛋白质同工型分布的“微调”）和成年状态的维持被认为依赖于神经，因为尽管去神经肌肉中的再生纤维可以表现出早期和随后的晚期胚胎染色特性，但它们又回到了早期胚胎状态；此外，成年肌肉去神经导致TnT同工型从成年状态转变为早期胚胎状态。
