Croop J, Toyama Y, Dlugosz A A, Holtzer H
Proc Natl Acad Sci U S A. 1980 Sep;77(9):5273-7. doi: 10.1073/pnas.77.9.5273.
Phorbol 12-myristate 13-acetate (PMA) has a prompt and selective catabolic effect on striated myofibrils in postmitotic myotubes. Fluorescein-labeled antibodies against light meromyosin were used to follow the effects of PMA on the muscle-specific myosin in myofibrils. The response of actin filaments was monitored by decoration with heavy meromyosin. The response of the two types of 10-nm filaments in myotubes was followed by fluorescein- and rhodamine-labeled antibodies to the fibroblastic and muscle-specific filament proteins, respectively. Within 2-3 days, PMA induced dismantling of virtually every striated myofibril in every myotube in the culture. These myotubes bound little or no anti-light meromyosin, and tests to detect the alpha-actin filaments of the myofibrils with heavy meromyosin were negative. In contrast, the nonmuscle actin in the subsarcolemmal microfilaments persisted in PMA-treated myotubes and was decorated with heavy meromyosin. The sarcoplasmic reticulum, mitochondria, and Golgi bodies appeared normal. Myotubes depleted of myofibrils by PMA displayed large numbers of muscle-specific 10-nm filaments. This preferential degradation of the myosin and actin of the myofibrils were reversible. These myotubes formed a normal complement of myofibrils 24-48 hr after removal of PMA. When, after 3 days in PMA, the cultures were treated for an additional 3-8 days, a transitory subpopulation of PMA-resistant myotubes appeared.
佛波醇12 -肉豆蔻酸酯13 -乙酸酯（PMA）对有丝分裂后肌管中的横纹肌肌原纤维具有迅速且选择性的分解代谢作用。使用针对轻酶解肌球蛋白的荧光素标记抗体来追踪PMA对肌原纤维中肌肉特异性肌球蛋白的影响。通过用重酶解肌球蛋白进行标记来监测肌动蛋白丝的反应。分别用荧光素和罗丹明标记的针对成纤维细胞和肌肉特异性细丝蛋白的抗体来追踪肌管中两种10纳米细丝的反应。在2至3天内，PMA诱导培养物中每个肌管内几乎所有横纹肌肌原纤维的拆解。这些肌管与抗轻酶解肌球蛋白结合很少或不结合，并且用重酶解肌球蛋白检测肌原纤维α -肌动蛋白丝的试验呈阴性。相比之下，肌膜下微丝中的非肌肉肌动蛋白在PMA处理的肌管中持续存在，并用重酶解肌球蛋白进行标记。肌浆网、线粒体和高尔基体看起来正常。被PMA耗尽肌原纤维的肌管显示出大量肌肉特异性的10纳米细丝。肌原纤维中肌球蛋白和肌动蛋白的这种优先降解是可逆的。在去除PMA后24至48小时，这些肌管形成了正常的肌原纤维补充。当在PMA中培养3天后，培养物再额外处理3至8天，出现了一个短暂的PMA抗性肌管亚群。
