Phosphorylation of mitogen-activated protein kinases is involved in the epidermal growth factor and phorbol ester, but not in the thyrotropin/cAMP, thyroid mitogenic pathway.
Phosphorylation of mitogen-activated protein kinases is involved in the epidermal growth factor and phorbol ester, but not in the thyrotropin/cAMP, thyroid mitogenic pathway.
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有丝分裂原激活蛋白激酶的磷酸化参与表皮生长因子和佛波酯，但不参与促甲状腺素/cAMP、甲状腺有丝分裂途径。
DOI：
10.1016/s0021-9258(18)52886-6
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
J. E. Dumont
中科院分区：
文献类型：
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作者：
Françoise Lamy;Françoise Wilkin;M. Baptist;James Posada;Pierre P. Roger;J. E. Dumont
在原代培养的狗甲状腺上皮细胞（甲状腺细胞）中，促甲状腺素（TSH）通过cAMP作用诱导增殖和分化表达，而表皮生长因子（EGF）和促肿瘤佛波酯诱导增殖和去分化。在这些细胞中，我们通过 32P 标记和二维凝胶电泳以及通过一维或二维凝胶电泳后用抗 MAP 激酶和抗磷酸酪氨酸抗体进行免疫检测，证明了丝裂原激活蛋白 (MAP) 激酶磷酸化。通过免疫化学染色证明了 MAP 激酶的定位。我们展示了以下结果。 (i) 与其他系统一样，EGF 和佛波酯诱导 p42 和 p44 MAP 激酶对酪氨酸、丝氨酸和苏氨酸进行磷酸化。这种效果很快，分别在 5 分钟和 15 分钟后达到峰值，随后缓慢下降。它先于 MAP 激酶免疫反应性从细胞质转移到细胞核。 (ii) 氨甲酰胆碱是 Ca(2+)-磷脂酰肌醇级联的有效刺激剂，不能诱导 DNA 合成，刺激 MAP 激酶磷酸化和核染色，其动力学与 EGF 作用后观察到的动力学相似，表明 MAP 激酶磷酸化不足以促进有丝分裂。 (iii) TSH 和毛喉素引发的 cAMP 依赖性有丝分裂级联在整个复制前阶段的任何时间都不涉及 p42 和 p44 MAP 激酶的磷酸化和核转位。因此，通过磷酸化激活 MAP 激酶并不是该有丝分裂级联中 G0-G1 转变的必要步骤。
In dog thyroid epithelial cells (thyrocytes) in primary culture, thyrotropin (TSH) acting through cAMP induces proliferation and differentiation expression, whereas epidermal growth factor (EGF) and tumor-promoting phorbol esters induce proliferation and dedifferentiation. In these cells we have demonstrated mitogen-activated protein (MAP) kinase phosphorylation by 32P labeling and two-dimensional gel electrophoresis and by immunodetection with anti-MAP kinase and anti-phosphotyrosine antibodies after one- or two-dimensional gel electrophoresis. MAP kinase localization was demonstrated by immunochemical staining. We show the following results. (i) As in other systems, EGF and phorbol esters induced p42 and p44 MAP kinases phosphorylation on tyrosine, serine, and threonine. This effect was rapid, peaking after 5 and 15 min, respectively, followed by a slow decline thereafter. It preceded a translocation of MAP kinase immunoreactivity from cytoplasm to nucleus. (ii) Carbamylcholine, a potent stimulator of the Ca(2+)-phosphatidylinositol cascade which is unable to induce DNA synthesis, stimulated MAP kinases phosphorylation and nuclear staining with kinetics similar to those observed after EGF action, indicating that MAP kinase phosphorylation was not sufficient for mitogenesis. (iii) The cAMP-dependent mitogenic cascade elicited by TSH and forskolin did not involve the phosphorylation and nuclear translocation of p42 and p44 MAP kinases at any time during the entire prereplicative phase. Activation of MAP kinases by phosphorylation is therefore not a necessary step in the G0-G1 transition in this mitogenic cascade.