Nolte C, Eigenthaler M, Schanzenbächer P, Walter U
Medizinische Universitätsklinik, Klinische Forschergruppe, Würzburg, Federal Republic of Germany.
Biochem Pharmacol. 1991 Jul 5;42(2):253-62. doi: 10.1016/0006-2952(91)90711-d.
The recent purification of a vasodilator-stimulated phosphoprotein (VASP) from human platelets and the development of a specific antiserum against VASP made it possible to study the quantitative effects of cAMP-elevating prostaglandins on cAMP-mediated phosphorylation of VASP in intact human platelets. Prostacyclin (PG-I2), prostaglandin-E1 (PG-E1) and the stable prostacyclinanalog Iloprost, all agents used for the treatment of peripheral vascular disease, induced rapid, stoichiometric and reversible phosphorylation of VASP in human platelets mediated by the cAMP-dependent protein kinase. However, there were substantial differences between these three cAMP-elevating prostaglandins with respect to their effects on extent, duration and reversibility of VASP phosphorylation. Maximal VASP phosphorylation was induced both by PG-I2 and Iloprost, but the PG-I2 effect was only of short duration in comparison to that of Iloprost. The extent of PG-E1-induced VASP phosphorylation was less than that observed with PG-I2 and Iloprost. In endothelial cell-platelet coincubations, an endothelial cell-derived, indomethacin-sensitive factor caused a rapid elevation of platelet cAMP level and VASP phosphorylation. These results provided direct evidence that human endothelial cells are capable of producing biologically active quantities of cAMP-elevating prostaglandins sufficient to induce stoichiometric cAMP-mediated protein phosphorylation in human platelets. VASP-phosphorylation induced by PG-I2 and PG-E1 was completely reversible after removal of the prostaglandins whereas this was only partially the case with Iloprost. In addition, evidence is presented that the prostaglandin-regulated adenylate cyclase system but not the cAMP-mediated protein phosphorylation desensitizes in human platelets after prolonged treatment with cAMP-elevating prostaglandins. VASP phosphorylation is proposed as a marker for quantitating aspects of vessel wall-platelet interaction.
最近从人血小板中纯化出血管舒张刺激磷蛋白（VASP）并研制出针对VASP的特异性抗血清，这使得研究提高cAMP的前列腺素对完整人血小板中cAMP介导的VASP磷酸化的定量影响成为可能。前列环素（PG-I2）、前列腺素E1（PG-E1）以及稳定的前列环素类似物伊洛前列素，这些用于治疗外周血管疾病的药物，均可通过cAMP依赖性蛋白激酶诱导人血小板中VASP快速、化学计量且可逆的磷酸化。然而，这三种提高cAMP的前列腺素在对VASP磷酸化的程度、持续时间和可逆性的影响方面存在显著差异。PG-I2和伊洛前列素均可诱导VASP的最大磷酸化，但与伊洛前列素相比，PG-I2的作用持续时间较短。PG-E1诱导的VASP磷酸化程度低于PG-I2和伊洛前列素。在内皮细胞与血小板共孵育中，一种内皮细胞衍生的、对吲哚美辛敏感的因子可导致血小板cAMP水平迅速升高及VASP磷酸化。这些结果提供了直接证据，表明人内皮细胞能够产生具有生物活性量的提高cAMP的前列腺素，足以在人血小板中诱导化学计量的cAMP介导的蛋白磷酸化。去除前列腺素后，PG-I2和PG-E1诱导的VASP磷酸化完全可逆，而伊洛前列素仅部分可逆。此外，有证据表明，在用提高cAMP的前列腺素长期处理后人血小板中，前列腺素调节的腺苷酸环化酶系统而非cAMP介导的蛋白磷酸化会发生脱敏。VASP磷酸化被提议作为定量血管壁与血小板相互作用方面的一个标志物。
