Department of Obstetrics and Gynecology, Perinatal Research Laboratories, University of Wisconsin, Madison, WI 53715, USA.
Placenta. 2009 Oct;30(10):907-13. doi: 10.1016/j.placenta.2009.07.003. Epub 2009 Aug 18.
Vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2) elicit cellular responses via activation of protein kinases and phosphatases. We have reported that the MEK1/2/ERK1/2 and PI3K/AKT1 pathways are critical for VEGF- and FGF2-stimulated ovine fetoplacental artery endothelial (OFPAE) cell proliferation. We have also shown that protein phosphatase 3 (PPP3) differentially modulates VEGF- and FGF2-stimulated cell proliferation and activation of ERK1/2 and AKT1 in OFPAE cells. Herein, we investigated if protein phosphatase 2 (PPP2) modulated VEGF- and FGF2-induced ERK1/2, AKT1, and p38 MAPK activation and VEGF- and FGF2-stimulated cell proliferation in OFPAE cells. Small interfering RNA (siRNA) specifically targeting human PPP2CA catalytic subunit alpha (PPP2CA) was used to suppress PPP2CA expression in OFPAE cells. When compared with scrambled siRNA, PPP2CA siRNA decreased (p<0.05) PPP2CA protein levels (approximately 70%) and activity (approximately 50%) without altering protein levels of PPP3 catalytic subunit alpha (PPP3CA), nitric oxide synthase 3 (NOS3), ERK1/2, AKT1, and p38 MAPK. FGF2, but not VEGF rapidly (< or =5 min) induced p38 MAPK phosphorylation. Suppression of PPP2CA enhanced (p<0.05) VEGF-induced AKT1, but not ERK1/2 phosphorylation, whereas inhibited (p<0.05) FGF2-induced ERK1/2 and p38 MAPK and slightly attenuated FGF2-induced AKT1 phosphorylation. Suppression of PPP2CA did not significantly affect VEGF- and FGF2-stimulated OFPAE cell proliferation. Thus, suppression of PPP2CA alone differentially modulated VEGF- and FGF2-induced ERK1/2, AKT1, and p38 MAPK activation, without altering VEGF- and FGF2-stimulated cell proliferation in OFPAE cells. These data also suggest that signaling molecules other than ERK1/2, AKT1, and p38 MAPK are important mediators for VEGF- and FGF2-stimulated OFPAE cell proliferation after PPP2CA suppression.
血管内皮生长因子 (VEGF) 和成纤维细胞生长因子 2 (FGF2) 通过激活蛋白激酶和磷酸酶来引发细胞反应。我们已经报道过，MEK1/2/ERK1/2 和 PI3K/AKT1 途径对于 VEGF 和 FGF2 刺激的羊胎盘中皮细胞 (OFPAE) 增殖至关重要。我们还表明，蛋白磷酸酶 3 (PPP3) 差异调节 VEGF 和 FGF2 刺激的细胞增殖以及 OFPAE 细胞中 ERK1/2 和 AKT1 的激活。在此，我们研究了蛋白磷酸酶 2 (PPP2) 是否调节 VEGF 和 FGF2 诱导的 ERK1/2、AKT1 和 p38 MAPK 激活以及 OFPAE 细胞中 VEGF 和 FGF2 刺激的细胞增殖。使用针对人 PPP2CA 催化亚基 α (PPP2CA) 的小干扰 RNA (siRNA) 特异性抑制 OFPAE 细胞中的 PPP2CA 表达。与 scrambled siRNA 相比，PPP2CA siRNA 降低了 PPP2CA 蛋白水平（约 70%）和活性（约 50%），而不改变 PPP3 催化亚基 α (PPP3CA)、一氧化氮合酶 3 (NOS3)、ERK1/2、AKT1 和 p38 MAPK 的蛋白水平。FGF2，但不是 VEGF，迅速（<或=5 分钟）诱导 p38 MAPK 磷酸化。抑制 PPP2CA 增强了（p<0.05）VEGF 诱导的 AKT1，但不是 ERK1/2 磷酸化，而抑制了（p<0.05）FGF2 诱导的 ERK1/2 和 p38 MAPK，并轻微减弱了 FGF2 诱导的 AKT1 磷酸化。抑制 PPP2CA 对 VEGF 和 FGF2 刺激的 OFPAE 细胞增殖没有显著影响。因此，单独抑制 PPP2CA 差异调节 VEGF 和 FGF2 诱导的 ERK1/2、AKT1 和 p38 MAPK 激活，而不改变 VEGF 和 FGF2 刺激的 OFPAE 细胞增殖。这些数据还表明，在 PPP2CA 抑制后，ERK1/2、AKT1 和 p38 MAPK 以外的信号分子对于 VEGF 和 FGF2 刺激的 OFPAE 细胞增殖是重要的介导物。
