Rao C V, Carman F R, Chegini N, Schultz G S
J Clin Endocrinol Metab. 1984 Jun;58(6):1034-42. doi: 10.1210/jcem-58-6-1034.
The present study demonstrates that human fetal membranes bind 125I-epidermal growth factor (125I-EGF), with chorion binding more than amnion. The chorion binding was also higher than that by decidua, but lower than in placenta. The lower binding by chorion compared to placenta was entirely attributable to a lower number of available EGF receptors and not to lower affinity. Chorion and placenta , but not amnion or decidua, from Cesarean section bound significantly more 125I-EGF when compared to tissues obtained after vaginal delivery. The binding of 125I-EGF to chorion exhibited dependency on time, temperature of incubation, pH of the incubation media, and amount of chorion protein. The 125I-EGF was not degraded during the binding reaction with chorion. The binding was specific in that unlabeled EGF inhibited 125I-EGF binding in a dose-dependent manner, whereas very high concentrations of other unlabeled hormones and growth factors had minimal effects on 125I-EGF binding. When some of these other hormones were tested for binding as tracers (125I-hCG, [3H]prostaglandin E1 and F2 alpha), neither chorion, amnion, decidua, nor placenta specifically bound these ligands. The 125I-EGF specific binding to chorion was saturable and a Scatchard plot of this data was curvilinear, which appears to be due to negative cooperativity. The apparent dissociation constant calculated from the initial slope of the plot was 0.20 nM, which is in excellent agreement with the concentration of unlabeled EGF required for half maximal inhibition of 125I-EGF binding, 0.26 nM. Autoradiography at the light microscope level revealed the presence of silver grains in amnion and chorion only when excess unlabeled EGF addition was withheld. The quantification of grains revealed the presence of a significantly (P less than 0.01) greater number of grains in chorion than in amnion, supporting the conclusion of the binding data. The physiological significance of EGF binding to fetal membranes and decidua is not known, but the considerable amount of EGF binding reported here suggests that they are target tissues for EGF.
本研究表明，人胎膜可结合125I-表皮生长因子（125I-EGF），其中绒毛膜的结合能力强于羊膜。绒毛膜的结合能力也高于蜕膜，但低于胎盘。与胎盘相比，绒毛膜结合能力较低完全归因于可用的EGF受体数量较少，而非亲和力较低。与经阴道分娩获得的组织相比，剖宫产术中获得的绒毛膜和胎盘（而非羊膜或蜕膜）结合的125I-EGF显著更多。125I-EGF与绒毛膜的结合表现出对时间、孵育温度、孵育培养基pH值以及绒毛膜蛋白量的依赖性。在与绒毛膜的结合反应过程中，125I-EGF未被降解。这种结合具有特异性，因为未标记的EGF以剂量依赖性方式抑制125I-EGF的结合，而非常高浓度的其他未标记激素和生长因子对125I-EGF的结合影响极小。当测试其中一些其他激素作为示踪剂的结合情况（125I-hCG、[3H]前列腺素E1和F2α）时，绒毛膜、羊膜、蜕膜和胎盘均未特异性结合这些配体。125I-EGF与绒毛膜的特异性结合是可饱和的，对此数据绘制的Scatchard图呈曲线状，这似乎是由于负协同作用所致。根据该图初始斜率计算出的表观解离常数为0.20 nM，这与半数最大抑制125I-EGF结合所需的未标记EGF浓度0.26 nM非常吻合。光学显微镜水平的放射自显影显示，仅在不添加过量未标记EGF时，羊膜和绒毛膜中才存在银颗粒。颗粒定量显示，绒毛膜中的颗粒数量显著多于羊膜（P小于0.01），支持了结合数据得出的结论。EGF与胎膜和蜕膜结合的生理意义尚不清楚，但此处报道的大量EGF结合表明它们是EGF的靶组织。
