Pfeilschifter J, Krempien R, Naumann A, Gronwald R G, Hoppe J, Ziegler R
Department of Internal Medicine I, University of Heidelberg, Germany.
Endocrinology. 1992 Apr;130(4):2059-66. doi: 10.1210/endo.130.4.1312439.
We examined receptor binding and metabolic effects of the platelet-derived growth factor (PDGF) isoforms AA, AB, and BB in cultures of osteoblastic cells from fetal rat calvaria. Saturation binding experiments demonstrated the presence of 6,000 binding sites for PDGF-AA, 42,000 for PDGF-AB, and 60,000 for PDGF-BB. Binding competition experiments were compatible with the recently postulated model of three PDGF receptor subtypes with differential affinity for the PDGF isoforms. The effects of the PDGF isoforms on DNA synthesis, collagen synthesis, and alkaline phosphatase activity in osteoblasts strictly correlated with the number of available binding sites. Accordingly, PDGF-BB was the most potent isoform, PDGF-AB was slightly less potent, and PDGF-AA was the least potent. In contrast, we found that PDGF-BB was less potent than PDGF-AB in increasing plasminogen activator activity in the osteoblast-conditioned medium. Our data strongly suggest that the PDGF receptor subtypes in fetal rat osteoblasts not only selectively bind one or more PDGF isoforms, but are also capable of responding differently to these isoforms.
我们检测了血小板衍生生长因子（PDGF）的AA、AB和BB亚型在胎鼠颅骨成骨细胞培养物中的受体结合及代谢效应。饱和结合实验表明，PDGF-AA有6000个结合位点，PDGF-AB有42000个，PDGF-BB有60000个。结合竞争实验与最近提出的三种对PDGF亚型具有不同亲和力的PDGF受体亚型模型相符。PDGF亚型对成骨细胞中DNA合成、胶原蛋白合成及碱性磷酸酶活性的影响与可用结合位点的数量严格相关。因此，PDGF-BB是最有效的亚型，PDGF-AB稍次，PDGF-AA最无效。相反，我们发现，在增加成骨细胞条件培养基中的纤溶酶原激活物活性方面，PDGF-BB比PDGF-AB效力更低。我们的数据有力地表明，胎鼠成骨细胞中的PDGF受体亚型不仅能选择性结合一种或多种PDGF亚型，而且对这些亚型的反应也有所不同。
