PLATELET-DERIVED GROWTH-FACTOR MIMICS PHORBOL DIESTER ACTION ON EPIDERMAL GROWTH-FACTOR RECEPTOR PHOSPHORYLATION AT THREONINE-654
PLATELET-DERIVED GROWTH-FACTOR MIMICS PHORBOL DIESTER ACTION ON EPIDERMAL GROWTH-FACTOR RECEPTOR PHOSPHORYLATION AT THREONINE-654
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DOI：
10.1073/pnas.82.12.4080
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发表时间：
1985-01-01
影响因子：
11.1
通讯作者：
CZECH, MP
中科院分区：
文献类型：
--
作者：
DAVIS, RJ;CZECH, MP
将血小板衍生生长因子（PDGF）添加到静止的WI-38人胎儿肺成纤维细胞中，模拟促肿瘤磷酸酯抑制125i标记的表皮生长因子（125I-EGF）高亲和力结合的作用。与phorbol diester一样，PDGF被发现可以增加免疫沉淀的EGF受体的磷酸化状态，这些EGF受体来自于用[32P]磷酸盐标记为平衡的完整成纤维细胞。EGF受体的磷氨基酸分析表明，PDGF和磷二酯均使[32P]磷丝氨酸和[32P]磷苏氨酸水平升高。EGF受体的磷酸化肽定位表明，PDGF增加了几个位点的磷酸化，并诱导了从对照细胞分离的EGF受体上未被磷酸化的位点的磷酸化。EGF受体上的后一个磷酸化位点被鉴定为Thr-654，先前在完整细胞中或在体外纯化的蛋白激酶C中被证明是磷酸化的。在[32P]磷酸盐标记的成纤维细胞中，PDGF模拟磷酸二酯的作用，抑制EGF受体依赖的Tyr磷酸化。这些结果与PDGF添加到成纤维细胞引起的二酰基甘油和Ca2+水平升高的假设一致，激活蛋白激酶C，该激酶至少部分地介导PDGF对EGF受体磷酸化的影响。蛋白激酶C可能在PDGF调控细胞代谢和增殖中发挥重要作用。
Addition of platelet-derived growth factor (PDGF) to quiescent WI-38 human fetal lung fibroblasts mimics the effect of tumor-promoting phorbol diesters to inhibit the high-affinity binding of 125I-labeled epidermal growth factor (125I-EGF). PDGF, like phorbol diesters, was found to increase the phosphorylation state of EGF receptors immunoprecipitated from intact fibroblasts that were labeled to equilibrium with [32P]phosphate. Phosphoamino acid analysis of the EGF receptors indicated that both PDGF and phorbol diesters increased the level of [32P]phosphoserine and [32P]phosphothreonine. Phosphopeptide mapping of the EGF receptor demonstrated that PDGF increased the phosphorylation of several sites and induced the phosphorylation of a site that was not observed to be phosphorylated on EGF receptors isolated from control cells. This latter phosphorylation site on the EGF receptor was identified as Thr-654, previously shown to be phosphorylated in response to phorbol diesters in intact cells or by purified protein kinase C in vitro. PDGF mimicked the action of phorbol diesters to inhibit the EGF-dependent Tyr phosphorylation of the EGF receptor in [32P]phosphate-labeled fibroblasts. These results are consistent with the hypothesis that increases in diacylglycerol and Ca2+ levels caused by addition of PDGF to fibroblasts activate protein kinase C and that this kinase, at least in part, mediates the effect of PDGF on the phosphorylation of the EGF receptor. Protein kinase C may play an important role in the regulation of cellular metabolism and proliferation by PDGF.