Cell Biology Section, Division of Intramural Research, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Exp Cell Res. 2010 Feb 15;316(4):507-16. doi: 10.1016/j.yexcr.2009.12.004. Epub 2009 Dec 16.
In this study, we demonstrate that protein kinase C (PKC) activators, including phorbol-12-myristate-13-acetate (PMA), 1,2-dioctanoyl-sn-glycerol (DOG), and platelet-derived growth factor alpha are potent inducers of angiopoietin-like protein 4 (ANGPTL4) expression in several normal lung cell types and carcinoma cell lines. In human airway smooth muscle (HASM) cells induction of ANGPTL4 expression is observed as early as 2 h after the addition of PMA. PMA also increases the level of ANGPTL4 protein released in the medium. PKC inhibitors Ro31-8820 and Gö6983 greatly inhibit the induction of ANGPTL4 mRNA by PMA suggesting that this up-regulation involves activation of PKC. Knockdown of several PKCs by corresponding siRNAs suggest a role for PKCalpha. PMA does not activate MAPK p38 and p38 inhibitors have little effect on the induction of ANGPTL4 indicating that p38 is not involved in the regulation of ANGPTL4 by PMA. In contrast, treatment of HASM by PMA induces phosphorylation and activation of Ra, MEK1/2, ERK1/2, JNK, Elk-1, and c-Jun. The Ras inhibitor manumycin A, the MEK1/2 inhibitor U0126, and the JNK inhibitor SP600125, greatly reduce the increase in ANGPTL4 expression by PMA. Knockdown of MEK1/2 and JNK1/2 expression by corresponding siRNAs inhibits the induction of ANGPTL4. Our observations suggest that the induction of ANGPTL4 by PMA in HASM involves the activation of PKC, ERK, and JNK pathways. This induction may play a role in tissue remodeling during lung injury and be implicated in several lung pathologies.
在这项研究中，我们证明蛋白激酶 C（PKC）激活剂，包括佛波醇-12-肉豆蔻酸-13-乙酸酯（PMA）、1,2-二油酰基-sn-甘油（DOG）和血小板衍生生长因子-α，可强烈诱导几种正常肺细胞类型和癌细胞系中血管生成素样蛋白 4（ANGPTL4）的表达。在人气道平滑肌（HASM）细胞中，添加 PMA 后仅 2 小时即可观察到 ANGPTL4 表达的诱导。PMA 还增加了释放到培养基中的 ANGPTL4 蛋白的水平。PKC 抑制剂 Ro31-8820 和 Gö6983 极大地抑制了 PMA 诱导的 ANGPTL4 mRNA 的诱导，表明这种上调涉及 PKC 的激活。用相应的 siRNA 敲低几种 PKC 表明 PKCalpha 起作用。PMA 不会激活 MAPK p38，p38 抑制剂对 ANGPTL4 的诱导几乎没有影响，表明 p38 不参与 PMA 对 ANGPTL4 的调节。相反，PMA 处理 HASM 可诱导 Ra、MEK1/2、ERK1/2、JNK、Elk-1 和 c-Jun 的磷酸化和激活。Ras 抑制剂马麦霉素 A、MEK1/2 抑制剂 U0126 和 JNK 抑制剂 SP600125 极大地减少了 PMA 对 ANGPTL4 表达增加的作用。用相应的 siRNA 敲低 MEK1/2 和 JNK1/2 表达可抑制 ANGPTL4 的诱导。我们的观察表明，PMA 在 HASM 中诱导 ANGPTL4 涉及 PKC、ERK 和 JNK 途径的激活。这种诱导可能在肺损伤期间的组织重塑中发挥作用，并与几种肺病理学有关。
