Role of ERK1/2 signaling during EGF-induced inhibition of palatal fusion.
Role of ERK1/2 signaling during EGF-induced inhibition of palatal fusion.
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DOI：
10.1016/s0012-1606(03)00275-6
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发表时间：
2003-08
影响因子：
2.7
通讯作者：
Tadashi Yamamoto;X. Cui;C. Shuler
中科院分区：
文献类型：
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作者：
Tadashi Yamamoto;X. Cui;C. Shuler
在哺乳动物腭融合过程中，内侧边缘上皮 (MEE) 细胞必须在相对的腭架初次接触之前停止 DNA 合成，然后选择性地从中线消失。外源性 EGF 已被证明可以抑制 DNA 合成的停止并诱发腭裂；然而，确切的细胞内机制尚未确定。我们假设 EGF 信号通过 ERK1/2 发挥作用，维持 MEE DNA 合成和细胞增殖，从而抑制腭融合过程。 E13 小鼠胚胎的腭架保存在器官培养物中并用 EGF 刺激。经过 EGF 处理的上颚未能与完整的 MEE 融合，并且具有显着的 ERK1/2 磷酸化。 EGF 诱导的 ERK1/2 磷酸化和 BrdU 掺入均位于 MEE 细胞的细胞核中。随后使用 U0126（一种 ERK1/2 磷酸化的特异性抑制剂）进行了抑制测定。 U0126 以剂量依赖性方式抑制 EGF 诱导的 ERK1/2 磷酸化，从而使 MEE 细胞停止增殖。 ERK1/2 失活以停止 MEE DNA 合成的阈值与拯救 EGF 诱导的腭裂表型所需的水平一致。这些结果表明 EGF 诱导的腭融合抑制依赖于核 ERK1/2 激活，并且在正常腭融合过程中必须严格调节该机制。
During mammalian palatal fusion, the medial edge epithelial (MEE) cells must stop DNA synthesis prior to the initial contact of opposing palatal shelves and thereafter selectively disappear from the midline. Exogenous EGF has been shown to inhibit the cessation of DNA synthesis and induce cleft palate; however, the precise intracellular mechanism has not been determined. We hypothesized that EGF signaling acting via ERK1/2 would maintain MEE DNA synthesis and cell proliferation and consequently inhibit the process of palatal fusion. Palatal shelves from E13 mouse embryos were maintained in organ cultures and stimulated with EGF. EGF-treated palates failed to fuse with intact MEE and had significant ERK1/2 phosphorylation. Both EGF-induced ERK1/2 phosphorylation and BrdU-incorporation were localized in the nucleus of MEE cells. Subsequent inhibition assays using U0126, a specific inhibitor of ERK1/2 phosphorylation, were conducted. U0126 inhibited EGF-induced ERK1/2 phosphorylation in a dose-dependent manner and consequently MEE cells stopped proliferation. The threshold of ERK1/2 inactivation to stop MEE DNA synthesis coincides with the level required to rescue the EGF-induced cleft palate phenotype. These results indicate that EGF-induced inhibition of palatal fusion is dependent on nuclear ERK1/2 activation and that this mechanism must be tightly regulated during normal palatal fusion.