Department of Dermatology, Seoul National University College of Medicine, Seoul, Republic of Korea.
J Dermatol Sci. 2011 Nov;64(2):134-41. doi: 10.1016/j.jdermsci.2011.07.002. Epub 2011 Aug 4.
Many extracellular stimuli, including epidermal growth factor (EGF), are known to induce MMP-1 expression. Recently, several reports have shown that ERK activity plays an important role in EGF-induced MMP-1 expression. However, EGF is also known to activate many signaling pathways in addition to the ERK pathway, but the roles of these pathways during the induction of MMP-1 by EGF are unclear.
We investigated the role of JNK, p38 MAPK, and PI3K/Akt pathways in EGF-induced MMP-1 expression in human skin fibroblasts. Then, we further explored the inhibitory effect of p38 MAPK pathway on EGF-induced MMP-1 expression and studied the molecular mechanisms involved in the processes.
Human skin fibroblasts were pretreated with various chemical inhibitors or small interfering RNA (siRNA) at the indicated concentrations and then treated with EGF, TNF-alpha, or IL-1beta for the indicated times. Protein and mRNA levels of various target molecules were assessed by Western blotting and quantitative real-time PCR, respectively.
We found that EGF-induced MMP-1 expression was positively regulated by JNK as well as ERK but negatively regulated by p38 MAPK in human skin fibroblasts. On the other hand, the PI3K/Akt pathway did not significantly affect MMP-1 induction by EGF. Then we found that the inhibition of p38 MAPK pathway specifically increased the MMP-1 expression stimulated by EGF but not by TNF-alpha or IL-1beta, indicating that the effect of p38 MAPK on MMP-1 expression may be stimulus-type specific in human skin fibroblasts. In addition, the inhibitory effect of p38 MAPK on EGF-induced MMP-1 expression was shown to be mainly mediated by p38-alpha MAPK. Our further studies showed that the inhibition of p38 MAPK but not PI3K specifically increased EGF-induced ERK and JNK activations, and that the augmentation of EGF-induced MMP-1 expression by p38 MAPK inhibition was significantly attenuated by inhibiting the activities of ERK and/or JNK.
Our results indicate that EGF-induced MMP-1 expression is differentially regulated by the JNK, p38 MAPK, and PI3K/Akt pathways, and suggest that p38 MAPK negatively regulates EGF-induced MMP-1 expression by suppressing the activations of ERK and JNK.
许多细胞外刺激物，包括表皮生长因子（EGF），已知可诱导 MMP-1 的表达。最近，有几项报告表明 ERK 活性在 EGF 诱导的 MMP-1 表达中起着重要作用。然而，EGF 除了 ERK 途径之外，还已知能激活许多信号通路，但这些通路在 EGF 诱导 MMP-1 表达过程中的作用尚不清楚。
我们研究了 JNK、p38MAPK 和 PI3K/Akt 通路在人皮肤成纤维细胞中 EGF 诱导的 MMP-1 表达中的作用。然后，我们进一步探讨了 p38MAPK 通路对 EGF 诱导的 MMP-1 表达的抑制作用，并研究了所涉及的分子机制。
用人皮肤成纤维细胞用不同浓度的各种化学抑制剂或小干扰 RNA（siRNA）预处理，然后用 EGF、TNF-α 或 IL-1β 处理指定时间。通过 Western 印迹和定量实时 PCR 分别评估各种靶分子的蛋白和 mRNA 水平。
我们发现 EGF 诱导的 MMP-1 表达在人皮肤成纤维细胞中受到 JNK 和 ERK 的正向调节，而受到 p38MAPK 的负向调节。另一方面，PI3K/Akt 通路对 EGF 诱导的 MMP-1 诱导没有显著影响。然后我们发现 p38MAPK 通路的抑制特异性增加了 EGF 刺激的 MMP-1 表达，但不增加 TNF-α 或 IL-1β 刺激的 MMP-1 表达，表明 p38MAPK 对 MMP-1 表达的影响可能在人皮肤成纤维细胞中具有刺激类型特异性。此外，p38MAPK 对 EGF 诱导的 MMP-1 表达的抑制作用主要是通过 p38-α MAPK 介导的。我们进一步的研究表明，p38MAPK 的抑制特异性增加了 EGF 诱导的 ERK 和 JNK 激活，而 p38MAPK 抑制对 EGF 诱导的 MMP-1 表达的增强作用显著被抑制 ERK 和/或 JNK 的活性所减弱。
我们的结果表明，EGF 诱导的 MMP-1 表达受 JNK、p38MAPK 和 PI3K/Akt 通路的差异调节，并表明 p38MAPK 通过抑制 ERK 和 JNK 的激活来负调节 EGF 诱导的 MMP-1 表达。
