RELATIVE BINDING AND BIOCHEMICAL EFFECTS OF HETERODIMERIC AND HOMODIMERIC ISOFORMS OF PLATELET-DERIVED GROWTH-FACTOR IN OSTEOBLAST-ENRICHED CULTURES FROM FETAL-RAT BONE
RELATIVE BINDING AND BIOCHEMICAL EFFECTS OF HETERODIMERIC AND HOMODIMERIC ISOFORMS OF PLATELET-DERIVED GROWTH-FACTOR IN OSTEOBLAST-ENRICHED CULTURES FROM FETAL-RAT BONE
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DOI：
10.1002/jcp.1041470306
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发表时间：
1991-06-01
影响因子：
5.6
通讯作者：
CANALIS, E
中科院分区：
文献类型：
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作者：
CENTRELLA, M;MCCARTHY, TL;CANALIS, E
血小板衍生生长因子（PDGF）作为包含PDGF-A或PDGF-B亚基的同源二聚体或异源二聚体存在，并且每种同种型存在于各种组织中，包括骨。 虽然已经在骨细胞和完整骨碎片的培养物中研究了PDGF-BB的刺激作用，但尚未报道可能在体内局部或全身产生的其他同种型的影响。 因此，在胎鼠骨的成骨细胞富集培养物中评价了重组人PDGF-BB、PDGF-AB和PDGF-AA。 在24小时内，这些因子在骨细胞DNA和蛋白质合成中产生分级反应，分别在约0.6、2.1和4.8 nM PDGF-BB、PDGF-AB和PDGF-AA时具有半数最大效应。 胶原和非胶原蛋白合成的增加被废除时，DNA合成被阻断与羟基脲。 此外，每个因素降低碱性磷酸酶活性，PDGF-BB是最具抑制性的。 用I-125-PDGF-BB或I-125-PDGF-AA和每种未标记的PDGF同种型进行的结合研究产生了离散的配体结合和置换模式：I-125-PDGF-BB结合优先被PDGF-BB置换（Ki几乎等于0.7 nM），较少被PDGF-AB置换（Ki几乎等于2.3 nM），而PDGF-AA置换较差。 相比之下，I-125-PDGF-AA结合被PDGF-AA可测量地降低（Ki几乎等于4.0 nM），但被PDGF-BB或PDGF-AB更有效地取代（各自的Ki几乎等于0.7 nM）。 这些研究表明，每个PDGF异构体产生的生化效应与结合位点的占有率成正比，并表明，有利于PDGF-B亚基结合的受体优先介导这些结果成骨细胞富集的骨细胞培养。
Platelet-derived growth factor (PDGF) exists as a homodimer or a heterodimer comprising either PDGF-A or PDGF-B subunits, and each isoform occurs in various tissues, including bone. Although the stimulatory effects of PDGF-BB have been studied in cultures of bone cells and intact bone fragments, the influence of other isoforms that may arise locally or systemically in vivo, has not been reported. Therefore recombinant human PDGF-BB, PDGF-AB, and PDGF-AA were evaluated in osteoblast-enriched cultures from fetal rat bone. Within 24 hours these factors produced a graded response in bone cell DNA and protein synthesis, with half-maximal effects at approximately 0.6, 2.1, and 4.8 nM PDGF-BB, PDGF-AB, and PDGF-AA, respectively. Increases in collagen and noncollagen protein synthesis were abrogated when DNA synthesis was blocked with hydroxyurea. Furthermore, each factor reduced alkaline phosphatase activity, PDGF-BB being the most inhibitory. Binding studies with I-125-PDGF-BB or I-125-PDGF-AA and each unlabeled PDGF isoform produced discrete ligand binding and displacement patterns: I-125-PDGF-BB binding was preferentially displaced by PDGF-BB (Ki almost-equal-to 0.7 nM), less by PDGF-AB (Ki almost-equal-to 2.3 nM) and poorly by PDGF-AA. In contrast, I-125-PDGF-AA binding was measurably reduced by PDGF-AA (Ki almost-equal-to 4.0 nM), but was more effectively displaced by PDGF-BB or PDGF-AB (each with Ki almost-equal-to 0.7 nM). These studies indicate that each PDGF isoform produces biochemical effects proportional to binding site occupancy and suggest that receptors that favor PDGF-B subunit binding preferentially mediate these results in oseteoblast-enriched bone cell cultures.