Role of GRK6 in the Regulation of Platelet Activation through Selective G Protein-Coupled Receptor (GPCR) Desensitization
Role of GRK6 in the Regulation of Platelet Activation through Selective G Protein-Coupled Receptor (GPCR) Desensitization
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DOI：
10.3390/ijms21113932
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发表时间：
2020-06-01
影响因子：
5.6
通讯作者：
Kim, Soochong
中科院分区：
文献类型：
--
作者：
Chaudhary, Preeti Kumari;Kim, Sanggu;Kim, Soochong
血小板G蛋白偶联受体（GPCRs）通过介导对各种激动剂（包括二磷酸腺苷（ADP）、血栓素A（2）和凝血酶）的反应来调节血小板功能。虽然GPCR激酶（GRKs）被认为在大多数GPCR功能中具有关键作用，但关于血小板中GPCR信号转导的调节和GRKs的GPCR脱敏机制知之甚少。在这项研究中，我们研究了GRK 6的功能作用和GRK 6在血小板中调节特异性GPCR脱敏的分子基础。我们使用GRK 6基因敲除小鼠来评估GRK 6在血小板活化中的功能作用。与野生型（WT）血小板相比，GRK 6（-/-）血小板中由2-MeSADP、U46619、凝血酶和AYPGKF诱导的血小板聚集、致密颗粒和α颗粒分泌以及纤维蛋白原受体活化显著增强。然而，胶原相关肽（CRP）诱导的血小板聚集和分泌GRK 6（-/-）血小板不受影响。有趣的是，分别激活G（q）-偶联的5 HT（2A）和G（z）-偶联的α（2A）肾上腺素能受体的5-羟色胺和肾上腺素共刺激诱导的血小板聚集在GRK 6（-/-）血小板中不受影响，表明GRK 6参与特异性GPCR调节。此外，响应于ADP和AYPGKF的第二次激发的血小板聚集在GRK 6（-/-）血小板中恢复，而激动剂的再刺激不能诱导WT血小板中的聚集，表明GRK 6有助于P2 Y（1）、P2 Y（12）和PAR 4受体脱敏。此外，在GRK 6（-/-）血小板中，2-MeSADP诱导的Akt磷酸化和AYPGKF诱导的Akt、细胞外信号相关激酶（ERK）和蛋白激酶C δ（PKC δ）磷酸化显著增强。最后，GRK 6（-/-）小鼠在FeCl 3损伤颈动脉后表现出增强和稳定的血栓形成，并且尾部出血时间更短，表明GRK 6（-/-）小鼠更容易血栓形成和止血。我们的结论是，GRK 6通过选择性GPCR脱敏在调节血小板功能反应和血栓形成中起着重要作用。
Platelet G protein-coupled receptors (GPCRs) regulate platelet function by mediating the response to various agonists, including adenosine diphosphate (ADP), thromboxane A(2), and thrombin. Although GPCR kinases (GRKs) are considered to have the crucial roles in most GPCR functions, little is known regarding the regulation of GPCR signaling and mechanisms of GPCR desensitization by GRKs in platelets. In this study, we investigated the functional role of GRK6 and the molecular basis for regulation of specific GPCR desensitization by GRK6 in platelets. We used GRK6 knockout mice to evaluate the functional role of GRK6 in platelet activation. Platelet aggregation, dense- and alpha-granule secretion, and fibrinogen receptor activation induced by 2-MeSADP, U46619, thrombin, and AYPGKF were significantly potentiated in GRK6(-/-) platelets compared to the wild-type (WT) platelets. However, collagen-related peptide (CRP)-induced platelet aggregation and secretion were not affected in GRK6(-/-) platelets. Interestingly, platelet aggregation induced by co-stimulation of serotonin and epinephrine which activate G(q)-coupled 5HT(2A) and G(z)-coupled alpha(2A) adrenergic receptors, respectively, was not affected in GRK6(-/-) platelets, suggesting that GRK6 was involved in specific GPCR regulation. In addition, platelet aggregation in response to the second challenge of ADP and AYPGKF was restored in GRK6(-/-) platelets whereas re-stimulation of the agonist failed to induce aggregation in WT platelets, indicating that GRK6 contributed to P2Y(1), P2Y(12), and PAR4 receptor desensitization. Furthermore, 2-MeSADP-induced Akt phosphorylation and AYPGKF-induced Akt, extracellular signal-related kinase (ERK), and protein kinase C delta (PKC delta) phosphorylation were significantly potentiated in GRK6(-/-) platelets. Finally, GRK6(-/-) mice exhibited an enhanced and stable thrombus formation after FeCl3 injury to the carotid artery and shorter tail bleeding times, indicating that GRK6(-/-) mice were more susceptible to thrombosis and hemostasis. We conclude that GRK6 plays an important role in regulating platelet functional responses and thrombus formation through selective GPCR desensitization.