Cytokine receptor-mediated regulation of MAP kinases in human platelets

人血小板中细胞因子受体介导的 MAP 激酶调节

• 批准号: 09671109
• 负责人: TAKAYAMA Hiroshi
• 金额: $ 1.98万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09671109/
• 关键词: Thrombopoietin; platelets; MAP kinase; protein kinase C; Cytoskeleton

The thrombopoietin (TPO) receptor is expressed in the megakaryocytic lineage from late progenitors to platelets. We investigated the effect of TPO on the extracellular signal-regulated kinase (ERK) activation pathway in human platelets. TPO by itself did not activate ERK1, ERK2 and protein kinase C(PKC), whereas TPO directly enhanced the PKC-dependent activation of ERKs induced by other agonists including thrombin and phorbol esters, without affecting the PKC activation by those agonists. TPO did not activate the mitogen-activated protein kinase/ERK kinases, MEK1 and MEK2, but activated Raf-1 and directly augmented the PKC-mediated MEK activation, suggesting that TPO primarily potentiates the ERK pathway through regulating MEKs or upstream steps of MEKs including Raf-1. The MEK inhibitor PD098059 failed to affect not only thrombin-induced or phorbol ester-induced aggregation, but also potentiation of aggregation by TPO, denying the primary involvement of ERKs and MEKs in those events. … More ERKs and MEKs were located mainly in the detergent-soluble/non-cytoskeletal fractions. ERKs but not MEKs were relocated to the cytoskeleton following platelet aggregation and actin polymerization. These data indicate that TPO synergizes with other agonists in the ERK activation pathway of platelets and that this synergy might affect functions of the cytoskeleton possibly regulated by ERKs.TPO does not induce aggregation by itself but potentiates other-agonist-induced aggregation in aspirin-treated or -untreated platelets in vivo. Since we found that both ERKs and MEKs were not primarily involved in platelet aggregation as described above, we investigated effects of TPO on activation of p38 mitogen-activated protein kinase to study how TPO affects platelet functions. Thrombin but not phorbol 12, 13-dibutyrate(PDBu) activated p38 irrespective of aspirin pretreatment TPO did not activate p38 by itself, whereas TPO pretreatment potentiated thrombin-induced activation of p38, whether platelet were aspirinized or not. TPO also potentiated p38 activation induced by a thrombin receptor agonist peptide, a thromboxane A2 analogue, collagen, crosslinking the glycoprotein VI, ADP, and epinephrine. TPO did not promote phosphorylation of Hsp27 and cytosolic phospholipase A2 by itself but enhanced thrombin-induced phosphorylation of them. The specific p38 inhibitor SB203580 strongly inhibited such phosphorylation, confirming that it is mediated via the p38 pathway. SB203580 inhibited, but not completely, ADP- or thrombin-induced aggregation and its enhancement by TPO, whether platelets were aspirinized or not In contrast, although TPO also potentiated PDBu-induced aggregation in aspirinized platelets, SB203580 did not inhibit it irrespective of TPO pretreatment. The p38 pathway could be one of the mechanisms by which TPO potentiates agonist-induced aggregation in both aspirin-sensitive and -insensitive manners. Less

血小板素（TPO）受体在从晚祖细胞到血小板的巨核细胞谱系中表达。我们研究了TPO对人血小板中细胞外信号调节激酶（ERK）活化途径的影响。 TPO本身并未激活ERK1，ERK2和蛋白激酶C（PKC），而TPO直接增强了其他激动剂引起的ERK的PKC依赖性激活，包括凝血酶酯和phorbol酯，而不会影响这些激动剂的PKC激活。 TPO没有激活有丝分裂原激活的蛋白激酶/ERK激酶，MEK1和MEK2，而是激活了RAF-1，并直接增强了PKC介导的MEK激活，这表明TPO主要通过调节MEK或MEKS上游步骤对ERK途径潜力，包括RAF-1，包括RAF-1。 MEK抑制剂PD098059不仅影响凝血酶引起的或phobol酯诱导的聚集，而且还没有影响TPO聚集的潜力，从而否认Erks和Meks在这些事件中的主要参与。 …更多的ERK和MEK主要位于确定溶剂/非周期性骨骼分数中。 ERK，但不是Meks在血小板聚集和肌动蛋白聚合后的细胞骨架。这些数据表明，TPO与其他血小板的ERK激活途径中的其他激动剂合成，并且这种协同作用可能会影响ERKS.TPO调控的细胞骨架的功能。TPO本身不会诱导聚集本身，但潜在潜在的可能会导致其他动力学诱导的在Apperin-droweated treated-ununtreateateateated palteated palteleatedpalleatedpletelets invo中。由于我们发现ERK和MEK都不是如上所述的主要参与血小板聚集的，因此我们研究了TPO对p38有丝分裂原激活蛋白激酶激活的影响，以研究TPO如何影响血小板功能。凝血酶12、13-二丁酸酯（PDBU）激活的p38激活的p38，不论阿司匹林预处理TPO是否本身不会激活p38，而TPO预处理潜在的凝血酶诱导的p38的激活，无论是p38的激活，无论是p38的激活。 TPO还可能由凝血酶受体激动剂，血栓烷A2模拟，胶原蛋白，糖蛋白VI，ADP和肾上腺素交联引起的p38激活。 TPO本身并未促进HSP27和胞质磷脂酶A2的磷酸化，而是增强了凝血酶诱导的磷酸化。特定的p38抑制剂SB203580强烈抑制了这种磷酸化，证实了它是通过p38途径介导的。 SB203580抑制了ADP-或凝血酶诱导的汇总及其通过TPO的增强，无论是血小板是否是在格式化的，尽管TPO还具有PDBU诱导的Apphinized Platelets诱导的PDBU诱导的聚合，SB203580在SB203580中均未抑制TPO的Preteartive tpepto pretreateation。 p38途径可能是TPO潜在主义者对阿司匹林敏感和不敏感的举止诱导的聚集的机制之一。较少的

项目成果

Y.Ezumi,T.Uchiyama and H.Takayama: "Thrombopoietin potentiates the protein-kinase-C-mediated activation of mitogen-activated protein kinase/ERK kinases and...." Eur.J.Biochem.258. 976-985 (1998)

Y.Ezumi、T.Uchiyama 和 H.Takayama：“血小板生成素增强蛋白激酶 C 介导的丝裂原激活蛋白激酶/ERK 激酶的激活，并且……”Eur.J.Biochem.258。

Y.Ezumi, T.Uchiyama and H.Takayama: "Thrombopoietin potentiates the protein-kinase-C-mediated activation of mitogen Activated protein kinase/ERK kinases and..." Eur.J.Biochem. 258. 976-985 (1998)

Y.Ezumi、T.Uchiyama 和 H.Takayama：“血小板生成素增强蛋白激酶 C 介导的有丝分裂原活化蛋白激酶/ERK 激酶的激活，并且……”Eur.J.Biochem。

Y.Ezumi, T. Uchiyama and H. Takayama: "Thrombopoietin potentiates the protein-kinase-C-mediated activation of mitogen-activated protein kinase/ERK kinases and...." Eur. J. Biochem.258. 976-985 (1998)

Y.Ezumi、T. Uchiyama 和 H. Takayama：“血小板生成素增强蛋白激酶 C 介导的丝裂原激活蛋白激酶/ERK 激酶的激活，并且……”Eur。

Y.Ezumi & H.Takayama: "Thrombopoietin Potentiates The Protein Kinase C-mediated Activation of Mitogen-activated Protein Kinase/ERK Kinase and ......" Blood. (発表予定).

Y.Ezumi 和 H.Takayama：“血小板生成素增强蛋白激酶 C 介导的丝裂原激活蛋白激酶/ERK 激酶的激活和......”血液（待提交）。