EGF-INDUCED MITOGENESIS IN PROXIMAL TUBULAR CELLS - POTENTIATION BY ANGIOTENSIN-II
EGF-INDUCED MITOGENESIS IN PROXIMAL TUBULAR CELLS - POTENTIATION BY ANGIOTENSIN-II
复制标题
DOI：
10.1152/ajprenal.1987.253.2.f299
复制
发表时间：
1987-08-01
影响因子：
--
通讯作者：
FINE, LG
中科院分区：
文献类型：
--
作者：
NORMAN, J;BADIEDEZFOOLY, B;FINE, LG
用原代培养的兔近曲小管上皮细胞研究了表皮生长因子（EGF）的促有丝分裂作用及其结合特性。EGF被发现是一种有效的有丝分裂原和刺激DNA合成18倍以上的水平观察到静止细胞。用125 I-EGF作为配体，在培养的近端肾小管细胞上鉴定出两类特异性EGF受体，即，解离常数（Kd）为0.3nM，最大结合（Bmax）为1.7 × 104的高亲和性受体。104受体/细胞和Kd为1.9nM和Bmax为5.3 × 104的低亲和力受体。104个受体/细胞。由于血管紧张素II（ANG II）似乎具有许多共同的生长因子的属性，我们还研究了这些细胞上的ANG II和EGF的相互作用。ANG Ⅱ无促有丝分裂作用，但能增强EGF的促有丝分裂作用，最大作用为10-9 M。EGF诱导的有丝分裂发生的剂量-反应曲线在10-9 M ANG II存在下向左移动，使近似半最大刺激浓度从3 × 10 - 6降低到10 × 10 - 6。10-8至5倍。10-9 M. ANG II也刺激前列腺素E2（PGE 2）的释放，但抑制基础和ANG II刺激的PGE 2合成对有丝分裂没有影响。血管紧张素II没有影响EGF的高亲和力受体的结合，从1至20小时，并没有改变受体下调EGF或下调后的受体重新插入的过程。ANG Ⅱ（10 ~（-9）M）对细胞蛋白质含量、RNA和蛋白质合成、Na ~+-H ~+逆向转运和细胞内游离Ca ~（2+）浓度无影响。更高浓度的ANG II（5 × 10 - 6）可使血管紧张素Ⅱ（ANG Ⅱ）的浓度降低。10-8至5倍。10-6 M）导致胞质游离Ca 2+浓度的快速和短暂的剂量依赖性升高。这些研究表明，血管紧张素II增强EGF诱导的有丝分裂在一个或多个postreceptor步骤，可能包括细胞内Ca 2+浓度的微小变化。
The mitogenic effect of epidermal growth factor (EGF) and the characteristics of EGF binding were studied on primary cultures of rabbit proximal tubular cells. EGF was found to be a potent mitogen and stimulated DNA synthesis 18-fold above the level observed in quiescent cells. Using 125I-EGF as a ligand, two classes of specific EGF receptors were identified on the proximal tubular cell in culture, i.e., a high-affinity receptor with a dissociation constant (Kd) of 0.3 nM and maximal binding (Bmax) of 1.7 .times. 104 receptors/ cell and a low-affinity receptor with a Kd of 1.9 nM and Bmax of 5.3 .times. 104 receptors/cell. Because angiotensin II (ANG II) appeared to possess many properties common to growth factors, we also examined the interaction of ANG II and EGF on these cells. ANG II was not mitogenic, but it potentiated the mitogenic effect of EGF with a maximal effect of 10-9 M. The dose-response curve of EGF-induced mitogenesis was shifted to the left in the presence of 10-9 M ANG II, decreasing the approximate half-maximal stimulatory concentration from 3 .times. 10-8 to 5 .times. 10-9 M. ANG II also stimulated prostaglandin E2 (PGE2) release, but inhibition of basal and ANG II-stimulated PGE2 synthesis had no effect on mitogenesis. ANG II had no effect on the binding of EGF to the high-affinity receptor from 1 to 20 h and did not alter receptor downregulation by EGF or the process of receptor reinsertion after downregulation. ANG II (10-9 M) had no effect on cell protein content, RNA and protein synthesis, Na+-H+ antiport, and intracellular free Ca2+ concentration. Higher concentrations of ANG II (5 .times. 10-8 to 5 .times. 10-6 M) led to a rapid and transient dose-dependent rise in cytosolic free Ca2+ concentration. These studies demonstrate that ANG II potentiates EGF-induced mitogenesis at one or more postreceptor steps that may include small changes in cytosolic Ca2+ concentration.