Acceleration of myosin light chain dephosphorylation and relaxation of smooth muscle by telokin - Synergism with cyclic nucleotide-activated kinase
Acceleration of myosin light chain dephosphorylation and relaxation of smooth muscle by telokin - Synergism with cyclic nucleotide-activated kinase
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DOI：
10.1074/jbc.273.18.11362
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发表时间：
1998-05-01
影响因子：
4.8
通讯作者：
Somlyo, AP
中科院分区：
文献类型：
--
作者：
Wu, XQ;Haystead, TAJ;Somlyo, AP
P-32 与 telokin（一种平滑肌特异性 17-18 kDa、酸性（pI 4.2-4.4）蛋白）的掺入在完整兔回肠平滑肌（回肠）中通过毛喉素 (20 μM) 增加，在 α-毒素渗透性回肠中通过 8-溴环 GRIP (100 μm) 增加。从火鸡砂中纯化的天然 telokin (5-20 mu M) 和在大肠杆菌中表达并纯化至 >90% 纯度的重组兔 telokin，诱导剂量依赖性松弛，与调节性肌球蛋白轻链磷酸化显着降低相关，但不影响用 0.1% Triton X-100 透化的回肠调节性肌球蛋白轻链的硫代磷酸化率。在使用 0.1% Triton X-100 的长时间透化（>20 分钟）期间，内源性 telokin 从回肠丢失，丢失的时间进程与 8-溴环 GRIP 诱导的钙脱敏的丢失相关。重组和天然砂囊端蛋白在体外被 cAMP 依赖性蛋白激酶、cGMP 依赖性蛋白激酶和 p42/44 丝裂原激活蛋白激酶的催化亚基磷酸化；重组蛋白也被钙调蛋白依赖性蛋白激酶 II 磷酸化。当同时添加到耗尽内源性 telokin 的回肠时，由 8-溴环 GMP (50 μM) 磷酸化重组 telokin (10 μM) 激活的外源 cGMP 依赖性蛋白激酶 (0.5 μM)，并且它们的松弛作用相互增强。 Forskolin (20 μM) 也增加了完整回肠中 telokin 的磷酸化。我们得出结论，telokin 通过增强肌球蛋白轻链磷酸酶活性来诱导平滑肌钙脱敏，并且 telokin 的 cGMP 和/或 cAMP 依赖性磷酸化上调其松弛作用。
Incorporation of P-32 into telokin, a smooth muscle-specific, 17-18-kDa, acidic (pI 4.2-4.4) protein, was increased by forskolin (20 mu M) in intact rabbit ileum smooth muscle (ileum) and by 8-bromo-cyclic GRIP (100 mu m) in alpha-toxin-permeabilized ileum. Native telokin (5-20 mu M), purified from turkey gizzard, and recombinant rabbit telokin, expressed in Escherichia coli and purified to >90% purity, induced dose-dependent relaxation, associated with a significant decrease in regulatory myosin light chain phosphorylation, without affecting the rate of thiophosphorylation of regulatory myosin Light chain of ileum permeabilized with 0.1% Triton X-100. Endogenous telokin was lost from ileum during prolonged permeabilization (>20 min) with 0.1% Triton X-100, and the time course of loss was correlated with the loss of 8-bromo-cyclic GRIP-induced calcium desensitization. Recombinant and native gizzard telokins were phosphorylated, in vitro, by the catalytic subunit of cAMP-dependent protein kinase, cGMP-dependent protein kinase, and p42/44 mitogen-activated protein kinase; the recombinant protein was also phosphorylated by calmodulin dependent protein kinase II. Exogenous cGMP-dependent protein kinase (0.5 mu M) activated by 8-bromo-cyclic GMP (50 mu M) phosphorylated recombinant telokin (10 mu M) when added concurrently to ileum depleted of its endogenous telokin, and their relaxant effects were mutually potentiated Forskolin (20 mu M) also increased phosphorylation of telokin in intact ileum. We conclude that telokin induces calcium desensitization in smooth muscle by enhancing myosin light chain phosphatase activity and cGMP- and/or cAMP-dependent phosphorylation of telokin up-regulates its relaxant effect.