Bryckaert M C, Rendu F, Tobelem G, Wasteson A
Hôpital Lariboisière, Institut National de la Santé et de la Recherche Médicale U 150, Paris, France.
J Biol Chem. 1989 Mar 15;264(8):4336-41.
Platelet-derived growth factor (PDGF) is known to inhibit collagen-induced platelet aggregation. Collagen-induced binding of 125I-PDGF to human washed platelets was therefore investigated. It was found 1) to be time-dependent, reaching a plateau at 20 degrees C after 30 min, 2) collagen concentration-dependent, 3) specifically inhibited by unlabeled PDGF, and 4) saturable. Scatchard plot analysis showed a single class of sites with 3000 +/- 450 molecules bound/cell and an apparent KD of 1.2 +/- 0.2 10(-8) M. The effects of PDGF on collagen-induced phosphoinositide breakdown and protein phosphorylation were also investigated. At 50 ng/ml PDGF, a concentration which completely inhibited collagen-induced aggregation, the breakdown of [32P]phosphatidylinositol 4,5-biphosphate (PIP2) and [32P]phosphatidylinositol 4-phosphate (PIP) was observed, but the subsequent replenishment of [32P]PIP2 was inhibited. The same PDGF concentration totally inhibited collagen-induced phosphatidic acid formation. PDGF also completely prevented phosphorylation of P43 and P20, as a result of protein kinase C activation consecutive to phosphoinositide metabolism. These results suggest that (i) a specific PDGF receptor can be induced by collagen, and (ii) PDGF can effect the early events of collagen-induced platelet activation by inhibiting PIP2 resynthesis and P43 and P20 phosphorylation. It is concluded that PDGF might be involved in a negative feed-back control of platelet activation.
已知血小板衍生生长因子（PDGF）可抑制胶原蛋白诱导的血小板聚集。因此，研究了胶原蛋白诱导的125I-PDGF与人洗涤血小板的结合情况。发现其具有以下特点：1）时间依赖性，在20℃下30分钟后达到平台期；2）胶原蛋白浓度依赖性；3）可被未标记的PDGF特异性抑制；4）具有饱和性。Scatchard图分析显示存在一类单一的结合位点，每个细胞结合3000±450个分子，表观解离常数（KD）为1.2±0.2×10-8M。还研究了PDGF对胶原蛋白诱导的磷酸肌醇分解和蛋白质磷酸化的影响。在50 ng/ml的PDGF浓度下（该浓度可完全抑制胶原蛋白诱导的聚集），观察到[32P]磷脂酰肌醇4,5-二磷酸（PIP2）和[32P]磷脂酰肌醇4-磷酸（PIP）的分解，但随后[32P]PIP2的补充受到抑制。相同的PDGF浓度完全抑制了胶原蛋白诱导的磷脂酸形成。由于磷酸肌醇代谢后蛋白激酶C的激活，PDGF还完全阻止了P43和P20的磷酸化。这些结果表明：（i）胶原蛋白可诱导特异性的PDGF受体；（ii）PDGF可通过抑制PIP2再合成以及P43和P20的磷酸化来影响胶原蛋白诱导的血小板激活的早期事件。得出的结论是，PDGF可能参与血小板激活的负反馈控制。
