Contractile activity modulates actin synthesis and turnover in cultured neonatal rat heart cells.
Contractile activity modulates actin synthesis and turnover in cultured neonatal rat heart cells.
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收缩活性调节培养的新生大鼠心脏细胞中肌动蛋白的合成和周转。
DOI：
10.1161/01.res.73.1.172
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发表时间：
1993
影响因子：
20.1
通讯作者：
Samarel,AM
中科院分区：
文献类型：
--
作者：
Sharp,WW;Terracio,L;Borg,TK;Samarel,AM
在这项研究中，主动张力的发展中发挥的作用，心肌细胞肌原纤维结构和细胞形状的形成和维持进行了研究。用钙通道阻滞剂维拉帕米抑制新生大鼠心肌细胞的自发收缩活动24 ~ 96小时。罗丹明鬼笔环肽染色的细胞的共聚焦显微镜显示，在收缩停滞的24小时内，肌原纤维的肌动蛋白丝不再在它们的I带和Z线彼此对齐。细胞形状也受到影响，细胞在保持附着于基底以及彼此附着的同时发展出较少的星状外观。到48小时，这些细胞中基本上不存在肌动蛋白原纤维。肌动蛋白的消失证实了肌动蛋白的合成和积累速率的测量和脉冲追踪生物合成标记实验。结果表明，虽然肌动蛋白的合成显着减少，在逮捕的心肌细胞，总细胞肌动蛋白的快速消失，主要是由于肌动蛋白降解率增加。用维拉帕米（或其他钙通道阻滞剂）阻断L-型钙通道所产生的收缩停滞比K+去极化更大程度地加速肌动蛋白降解。氯喹部分抑制肌动蛋白降解的加速速率，表明溶酶体蛋白水解可能参与肌动蛋白降解过程。蛋白激酶C的激活也部分抑制了肌动蛋白降解的加速率，但并没有恢复被逮捕的肌细胞中的肌动蛋白丝。肌动蛋白原纤维的重组和重组成横纹肌原纤维时发生的收缩活动恢复维拉帕米从培养基中。肌细胞重新组装肌动蛋白丝并恢复其细长形态所需的时间与细胞被抑制收缩的时间成正比。数据表明，主动张力发展的新生心肌细胞在文化中的丝状肌动蛋白结构的维护是至关重要的，通过涉及肌动蛋白的组装，拆卸和降解的机制。
In this study, the role that active tension development plays in the formation and maintenance of cardiac myocyte myofibrillar structure and cellular shape was investigated. By use of the calcium channel blocker verapamil, spontaneous contractile activity of neonatal rat heart myocytes was inhibited for 24 to 96 hours. Confocal microscopy of rhodamine phalloidin-stained cells revealed that, within 24 hours of contractile arrest, actin filaments of myofibrils were no longer aligned with one another at their I bands and Z lines. Cellular shape was also affected, with the cells developing a less stellate appearance while remaining attached to the substrate as well as to one another. By 48 hours, actin fibrils were largely absent from these cells. The disappearance of actin was confirmed by measurements of actin synthesis and accumulation rates and by pulse-chase biosynthetic labeling experiments. It was revealed that, although actin synthesis was significantly reduced in arrested myocytes, the rapid disappearance of total cellular actin was largely due to increased rates of actin degradation. Contractile arrest produced by L-type calcium channel blockade with verapamil (or other calcium channel blockers) accelerated actin degradation to a greater extent than K+ depolarization. Chloroquine partially suppressed the accelerated rate of actin degradation, indicating that lysosomal proteolysis may be involved in actin degradative processing. Protein kinase C activation also partially inhibited the accelerated rate of actin degradation but did not restore actin filaments in arrested myocytes. The reformation of actin fibrils and their reassembly into striated myofibrils occurred when contractile activity was restored by removal of verapamil from the culture medium. The period of time required for myocytes to reassemble actin filaments and to regain their elongated morphology was proportional to the period of time that the cells were inhibited from contracting. Data are presented to indicate that active tension development by neonatal cardiac myocytes in culture is critical to the maintenance of filamentous actin structure via mechanisms involving actin assembly, disassembly, and degradation.