Nonmuscle myosin II is responsible for maintaining endothelial cell basal tone and stress fiber integrity
Nonmuscle myosin II is responsible for maintaining endothelial cell basal tone and stress fiber integrity
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DOI：
10.1152/ajpcell.00318.2008
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发表时间：
2008-10-01
影响因子：
5.5
通讯作者：
Wysolmerski, Robert B.
中科院分区：
文献类型：
--
作者：
Goeckeler, Zoe M.;Bridgman, Paul C.;Wysolmerski, Robert B.
培养的融合内皮细胞表现出稳定的基底等距张力，这与构成型肌球蛋白II调节轻链（RLC）磷酸化有关。凝血酶治疗可引起等长张力的快速增加，同时伴有肌球蛋白II RLC磷酸化、肌动蛋白聚合和应激纤维重组，而肌球蛋白轻链激酶（MLCK）和rho激酶抑制剂可阻止这些反应。这些发现表明肌球蛋白II在调节内皮细胞张力中的核心作用。目前的研究检查了blebbistatin（一种肌球蛋白II活性的特异性抑制剂）对基础张力和凝血酶诱导的张力发展的影响。尽管blebbistatin治疗消除了基底张力，但这伴随着肌球蛋白II RLC磷酸化的增加。RLC磷酸化的增加是Ca2+依赖性的，并由MLCK介导。同样，blebbistatin抑制凝血素诱导的张力，而不干扰RLC磷酸化或f -肌动蛋白聚合的增加。Blebbistatin确实能阻止肌凝蛋白II丝的掺入和与聚合或重组的肌动蛋白丝的结合，从而导致应力纤维的消失。因此，blebbistatin对基底张力和诱导张力的抑制作用与肌球蛋白II活性维持应力纤维完整性的要求一致。
Cultured confluent endothelial cells exhibit stable basal isometric tone associated with constitutive myosin II regulatory light chain (RLC) phosphorylation. Thrombin treatment causes a rapid increase in isometric tension concomitant with myosin II RLC phosphorylation, actin polymerization, and stress fiber reorganization while inhibitors of myosin light chain kinase (MLCK) and Rho-kinase prevent these responses. These findings suggest a central role for myosin II in the regulation of endothelial cell tension. The present studies examine the effects of blebbistatin, a specific inhibitor of myosin II activity, on basal tone and thrombin-induced tension development. Although blebbistatin treatment abolished basal tension, this was accompanied by an increase in myosin II RLC phosphorylation. The increase in RLC phosphorylation was Ca2+ dependent and mediated by MLCK. Similarly, blebbistatin inhibited thrombin-induced tension without interfering with the increase in RLC phosphorylation or in F-actin polymerization. Blebbistatin did prevent myosin II filament incorporation and association with polymerizing or reorganized actin filaments leading to the disappearance of stress fibers. Thus the inhibitory effects of blebbistatin on basal tone and induced tension are consistent with a requirement for myosin II activity to maintain stress fiber integrity.