Ca2+-independent phospholipase A2-dependent sustained Rho-kinase activation exhibits all-or-none response
Ca2+-independent phospholipase A2-dependent sustained Rho-kinase activation exhibits all-or-none response
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DOI：
10.1111/j.1365-2443.2006.01001.x
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发表时间：
2006-09-01
期刊：
影响因子：
2.1
通讯作者：
Kuroda, Shinya
中科院分区：
文献类型：
--
作者：
Maeda, Akio;Ozaki, Yu-ichi;Kuroda, Shinya
细胞的持续收缩依赖于持续的Rho相关激酶（Rho激酶）激活。我们开发了一个Rho激酶途径的计算模型，以了解系统的特性。凝血酶依赖性的Rho激活和Ca2+增加的体内瞬时反应可以在计算机上再现。低和高凝血酶刺激分别在体内诱导肌球蛋白轻链（MLC）和肌球蛋白磷酸酶靶向亚基1（MYPT 1）的短暂和持续磷酸化。MLC和MYPT 1的瞬时磷酸化可以在计算机上重现，但它们的持续磷酸化不能。Rho激酶下游持续反应的体内和计算机模拟之间的这种差异表明，缺失的途径可能是导致持续Rho激酶活化的原因。我们通过实验发现，MLC和MYPT1的持续磷酸化表现出全或无反应。溴烯醇内酯是钙非依赖性磷脂酶A2（iPLA 2）的特异性抑制剂，可抑制MLC和MYPT 1的持续磷酸化，这表明持续的Rho激酶激活需要iPLA 2活性。因此，Rho激酶途径的系统分析鉴定了持续Rho激酶活化的新的iPLA 2依赖性机制，其表现出全或无响应。
Sustained contraction of cells depends on sustained Rho-associated kinase (Rho-kinase) activation. We developed a computational model of the Rho-kinase pathway to understand the systems characteristics. Thrombin-dependent in vivo transient responses of Rho activation and Ca2+ increase could be reproduced in silico. Low and high thrombin stimulation induced transient and sustained phosphorylation, respectively, of myosin light chain (MLC) and myosin phosphatase targeting subunit 1 (MYPT1) in vivo. The transient phosphorylation of MLC and MYPT1 could be reproduced in silico, but their sustained phosphorylation could not. This discrepancy between in vivo and in silico in the sustained responses downstream of Rho-kinase indicates that a missing pathway(s) may be responsible for the sustained Rho-kinase activation. We found, experimentally, that the sustained phosphorylation of MLC and MYPT1 exhibit all-or-none responses. Bromoenol lactone, a specific inhibitor of Ca2+-independent phospholipase A2 (iPLA2), inhibited sustained phosphorylation of MLC and MYPT1, which indicates that sustained Rho-kinase activation requires iPLA2 activity. Thus, the systems analysis of the Rho-kinase pathway identified a novel iPLA2-dependent mechanism of the sustained Rho-kinase activation, which exhibits an all-or-none response.