A ROLE FOR RHO-KINASE IN Ca2+-INDEPENDENT CONTRACTIONS INDUCED BY PHORBOL-12,13-DIBUTYRATE
A ROLE FOR RHO-KINASE IN Ca2+-INDEPENDENT CONTRACTIONS INDUCED BY PHORBOL-12,13-DIBUTYRATE
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DOI：
10.1111/j.1440-1681.2008.05045.x
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发表时间：
2009-03-01
影响因子：
2.9
通讯作者：
Kim, In Kyeom
中科院分区：
文献类型：
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作者：
Baek, Inji;Jeon, Su Bun;Kim, In Kyeom
1. phorbor -12,13-dibutyrate （PDBu）是蛋白激酶C （PKC）的激活剂，在生理盐溶液和Ca2+耗尽溶液中引起收缩。在本研究中，我们验证了rho激酶在PDBu诱导的血管平滑肌Ca2+非依赖性收缩中发挥作用的假设。在无Ca2+溶液中，0.1和1 μ mol/L PDBu诱导收缩和肌球蛋白轻链（MLC20）磷酸化，这两种反应都是在正常克雷布斯溶液中获得的约40%的反应。羟法舒地尔（H1152; 1 mu mol/L）是rho激酶的抑制剂，而不是肌球蛋白轻链激酶的抑制剂ML7 (10 mmol/L)，可以抑制pdbu2诱导的Ca2+非依赖性收缩。在无Ca2+溶液中，PDBu增加了肌球蛋白磷酸酶靶向亚基1 （MYPT1）和CPI-17 （pkc增强的17 kDa异三聚体肌球蛋白轻链磷酸酶抑制蛋白）的磷酸化。这种作用被H1152抑制，PKC.4的抑制剂Ro31-8220几乎完全消除了CPI-17的磷酸化。在无Ca2+溶液中，PDBu增加了GTP-RhoA （RhoA的活化形式）的量。这种增加被PKC抑制剂Ro31-8220阻断，但不被Rho激酶抑制剂H1152.5阻断。综上所述，RhoA/ rho激酶在PDBu诱导的血管平滑肌Ca2+非依赖性收缩中起重要作用。本研究结果表明，PDBu通过激活GTP-RhoA和随后磷酸化MYPT1和CPI-17来抑制肌球蛋白轻链磷酸酶（MLCP），从而诱导Ca2+非依赖性收缩。
1. Phorbol-12,13-dibutyrate (PDBu) is an activator of protein kinase C (PKC) that causes contractions in both physiological salt solutions and Ca2+-depleted solutions. In the present study, we tested the hypothesis that Rho-kinase plays a role in Ca2+-independent contractions induced by PDBu in vascular smooth muscles.2. In Ca2+-free solution, 0.1 and 1 mu mol/L PDBu induced contraction and myosin light chain (MLC20) phosphorylation, both of which were approximately 40% of responses obtained in normal Krebs' solution. Hydroxyfasudil (H1152; 1 mu mol/L), an inhibitor of Rho-kinase, but not ML7 (10 mmol/L), an inhibitor of myosin light chain kinase, inhibited Ca2+-independent contractions induced by PDBu.3. In Ca2+-free solution, PDBu increased phosphorylation of myosin phosphatase targeting subunit 1 (MYPT1) and CPI-17 (PKC-potentiated inhibitory protein for heterotrimeric myosin light chain phosphatase of 17 kDa). This action was inhibited by H1152, with the phosphorylation of CPI-17 almost completely abolished by 1 mu mol/L Ro31-8220, an inhibitor of PKC.4. In Ca2+-free solution, PDBu increased the amount of GTP-RhoA (an activated form of RhoA). This increase was blocked by the PKC inhibitor Ro31-8220, but not by the Rho kinase inhibitor H1152.5. In conclusion, RhoA/Rho-kinase plays an important role in Ca2+-independent contractions induced by PDBu in vascular smooth muscles. The results of the present study suggest that PDBu induces Ca2+-independent contractions by inhibiting myosin light chain phospatase (MLCP) through activation of GTP-RhoA and subsequent phosphorylation of MYPT1 and CPI-17.