CONTRACTION DUE TO MICROTUBULE DISRUPTION IS ASSOCIATED WITH INCREASED PHOSPHORYLATION OF MYOSIN REGULATORY LIGHT-CHAIN
CONTRACTION DUE TO MICROTUBULE DISRUPTION IS ASSOCIATED WITH INCREASED PHOSPHORYLATION OF MYOSIN REGULATORY LIGHT-CHAIN
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DOI：
10.1073/pnas.92.22.10252
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发表时间：
1995-10-24
影响因子：
11.1
通讯作者：
ELSON, EL
中科院分区：
文献类型：
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作者：
KOLODNEY, MS;ELSON, EL
微管被认为是一种刚性支柱，可以抵抗细胞收缩。与这一假设相一致，微管破坏增强了许多细胞类型施加的收缩力。我们研究了微管破坏的机械效应的另一种解释：微管通过影响肌球蛋白调节轻链的磷酸化来调节肌球蛋白的机械化学活性（LC(20)）。我们测量了附着在等距力传感器上的胶原晶格内的成纤维细胞群体产生的力。用nocodazole（微管聚合抑制剂）处理细胞，可以刺激等距收缩，在30分钟内达到峰值，通常是30%胎牛血清最大刺激后力增加的30-45%。诺可达唑治疗后的收缩与LC（20）磷酸化增加2- 4倍相关，加入诺可达唑后，力和LC（20）磷酸化的增加可以通过紫杉醇（以前的一般名称，紫杉醇）稳定微管来阻止或逆转，胎牛血清预处理增加力和LC（20）磷酸化减少微管破坏后的后续额外收缩。我们的研究结果表明，LC（20）的磷酸化是微管毒物和受体介导的激动剂刺激收缩的共同机制，微管组装改变对肌球蛋白活性的调节可能协调这些细胞骨架成分的生理功能。
Microtubules have been proposed to function as rigid struts which oppose cellular contraction, Consistent with this hypothesis, microtubule disruption strengthens the contractile force exerted by many cell types, We have investigated an alternative explanation for the mechanical effects of microtubule disruption: that microtubules modulate the mechanochemical activity of myosin by influencing phosphorylation of the myosin regulatory light chain (LC(20)). We measured the force produced by a population of fibroblasts within a collagen lattice attached to an isometric force transducer, Treatment of cells with nocodazole, an inhibitor of microtubule polymerization, stimulated an isometric contraction that reached its peak level within 30 min and was typically 30-45% of the force increase following maximal stimulation with 30% fetal bovine serum. The contraction following nocodazole treatment was associated with a 2- to 4-fold increase in LC(20) phosphorylation, The increases in both force and LC(20) phosphorylation, after addition of nocodazole, could be blocked or reversed by stabilizing the microtubules with paclitaxel (former generic name, taxol), Increasing force and LC(20) phosphorylation by pretreatment with fetal bovine serum decreased the subsequent additional contraction upon microtubule disruption, a finding that appears inconsistent with a load-shifting mechanism, Our results suggest that phosphorylation of LC(20) is a common mechanism for the contractions stimulated both by microtubule poisons and receptor-mediated agonists, The modulation of myosin activity by alterations in microtubule assembly may coordinate the physiological functions of these cytoskeletal components.