Regulation of myofibrillar accumulation in chick muscle cultures: evidence for the involvement of calcium and lysosomes in non-uniform turnover of contractile proteins.
Regulation of myofibrillar accumulation in chick muscle cultures: evidence for the involvement of calcium and lysosomes in non-uniform turnover of contractile proteins.
复制标题
鸡肌肉培养物中肌原纤维积累的调节：钙和溶酶体参与收缩蛋白不均匀周转的证据。
DOI：
10.1083/jcb.101.6.2383
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发表时间：
1985-12
影响因子：
7.8
通讯作者：
Etlinger, J D
中科院分区：
文献类型：
--
作者：
Silver, G;Etlinger, J D
在原代鸡腿骨骼肌培养中，研究了钙对肌原纤维周转的影响。此外，在subcontraction阈值水平（0.38 μ M）的钙离子载体A23187的外排率显着增加预载的45 Ca +2，但总蛋白质的积累没有影响。然而，A23187以及离子霉素导致肌原纤维蛋白、肌球蛋白重链（MHC）、肌球蛋白轻链1f（LC 1f）、2f（LC 2f）、α-肌动蛋白（Ac）和原肌球蛋白（TM）的积累减少。24 h后，A23187可提高LC 1f、LC 2f和TM的降解速率。相反，钙离子载体导致Ac和肌钙蛋白-C的降解减少，并且对MHC、肌钙蛋白-T、肌钙蛋白-I或α，β-结蛋白（Dm）的降解没有影响。此外，A23187没有改变总肌管蛋白的降解。离子载体对总肌管蛋白的合成几乎没有影响，但在48 h后引起MHC、LC 1f、LC 2f、Ac、TM和Dm的合成显著降低。钙刺激的肌原纤维蛋白降解的机制也进行了研究。增加的蛋白水解似乎涉及溶酶体途径，因为Ca++离子载体的作用可以被蛋白酶抑制剂亮抑酶肽和亲溶酶体剂甲胺和氯喹阻断。A23187的作用在存在血清的情况下发生，在这种情况下，未检测到总体蛋白质降解的溶酶体组分。A23187对肌原纤维蛋白降解率的差异效应表明收缩器的动态结构。
The effect of calcium on myofibrillar turnover in primary chick leg skeletal muscle cultures was examined. Addition of the calcium ionophore A23187 at subcontraction threshold levels (0.38 microM) increased significantly rates of efflux of preloaded 45Ca+2 but had no effect on total protein accumulation. However, A23187 as well as ionomycin caused decreased accumulation of the myofibrillar proteins, myosin heavy chain (MHC), myosin light chain 1f (LC1f), 2f (LC2f), alpha-actin (Ac), and tropomyosin (TM). A23187 increased the degradation rate of LC1f, LC2f, and TM after 24 h. In contrast, the calcium ionophore caused decreased degradation of Ac and troponin-C and had no effect on the degradation of MHC, troponin-T, troponin-I, or alpha, beta-desmin (Dm). In addition, A23187 did not alter degradation of total myotube protein. The ionophore had little or no effect on the synthesis of total myotube proteins, but caused a marked decrease in the synthesis of MHC, LC1f, LC2f, Ac, TM, and Dm after 48 h. The mechanisms involved in calcium-stimulated degradation of the myofibrillar proteins were also investigated. Increased proteolysis appeared to involve a lysosomal pathway, since the effect of the Ca++ ionophore could be blocked by the protease inhibitor leupeptin and the lysosomotropic agents methylamine and chloroquine. The effects of A23187 occur in the presence of serum, a condition in which no lysosomal component of overall protein degradation is detected. The differential effect of A23187 on the degradative rates of the myofibrillar proteins suggests a dynamic structure for the contractile apparatus.