cAMP signaling regulates platelet myosin light chain (MLC) phosphorylation and shape change through targeting the RhoA-Rho kinase-MLC phosphatase signaling pathway
cAMP signaling regulates platelet myosin light chain (MLC) phosphorylation and shape change through targeting the RhoA-Rho kinase-MLC phosphatase signaling pathway
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DOI：
10.1182/blood-2013-03-487850
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发表时间：
2013-11-14
期刊：
影响因子：
20.3
通讯作者：
Naseem, Khalid M.
中科院分区：
文献类型：
--
作者：
Aburima, Ahmed;Wraith, Katie S.;Naseem, Khalid M.
环磷酸腺苷（cAMP）依赖性信号通过未知机制调节血小板形状变化。我们研究了环磷酸腺苷信号对血小板收缩机制的影响。前列腺素E-1（PGE（1））介导的凝血酶刺激的形状变化的抑制伴随着肌球蛋白轻链（MLC）磷酸化的减少。由于凝血酶通过RhoA/Rho相关的、含有蛋白激酶（ROCK）的卷曲螺旋依赖性抑制MLC磷酸酶（MLCP）刺激磷酸化MLC，因此我们研究了cAMP对该途径的影响。凝血酶刺激RhoA的膜定位和RhoA/ROCK 2/肌球蛋白磷酸酶靶向亚基1（MYPT 1）信号复合物的形成。这导致ROCK介导的MYPT 1在苏氨酸853（thr（853））上的磷酸化，催化亚基蛋白磷酸酶1 δ（PP 1 δ）从MYPT 1解离，并抑制基础MLCP活性。用PGE（1）处理血小板可通过蛋白激酶A（PKA）依赖性方式阻止凝血酶诱导的磷酸化MYPT 1-thr（853）。分子机制的研究表明，PGE（1）通过需要cAMP和PKA的途径诱导RhoA在丝氨酸（188）上的磷酸化。该事件抑制RhoA的膜再定位，防止RhoA与ROCK 2和MYPT 1的缔合，减弱PP 1 δ与MYPT 1的解离，从而恢复基础MLCP活性，导致磷酸化MLC减少。这些数据揭示了cAMP-PKA信号通路调节血小板功能的新机制。
Cyclic adenosine monophosphate (cAMP)-dependent signaling modulates platelet shape change through unknown mechanisms. We examined the effects of cAMP signaling on platelet contractile machinery. Prostaglandin E-1 (PGE(1))-mediated inhibition of thrombin-stimulated shape change was accompanied by diminished phosphorylation of myosin light chain (MLC). Since thrombin stimulates phospho-MLC through RhoA/Rho-associated, coiled-coil containing protein kinase (ROCK)-dependent inhibition of MLC phosphatase (MLCP), we examined the effects of cAMP on this pathway. Thrombin stimulated the membrane localization of RhoA and the formation of a signaling complex of RhoA/ROCK2/myosin phosphatase-targeting subunit 1 (MYPT1). This resulted in ROCK-mediated phosphorylation of MYPT1 on threonine 853 (thr(853)), the disassociation of the catalytic subunit protein phosphatase 1 delta (PP1 delta) from MYPT1 and inhibition of basal MLCP activity. Treatment of platelets with PGE(1) prevented thrombin-induced phospho-MYPT1-thr(853) in a protein kinase A (PKA)-dependent manner. Examination of the molecular mechanisms revealed that PGE(1) induced the phosphorylation of RhoA on serine(188) through a pathway requiring cAMP and PKA. This event inhibited the membrane relocalization of RhoA, prevented the association of RhoA with ROCK2 and MYPT1, attenuated the dissociation of PP1 delta from MYPT1, and thereby restored basal MLCP activity leading to a decrease in phospho-MLC. These data reveal a new mechanism by which the cAMP-PKA signaling pathway regulates platelet function.