Black Samuel A, Palamakumbura Amitha H, Stan Maria, Trackman Philip C
Department of Periodontology and Oral Biology, Division of Oral Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts 02118, USA.
J Biol Chem. 2007 May 25;282(21):15416-29. doi: 10.1074/jbc.M610432200. Epub 2007 Apr 10.
Prostaglandin E(2) blocks transforming growth factor TGF beta1-induced CCN2/CTGF expression in lung and kidney fibroblasts. PGE(2) levels are high in gingival tissues yet CCN2/CTGF expression is elevated in fibrotic gingival overgrowth. Gingival fibroblast expression of CCN2/CTGF in the presence of PGE(2) led us to compare the regulation of CCN2/CTGF expression in fibroblasts cultured from different tissues. Data demonstrate that the TGFbeta1-induced expression of CCN2/CTGF in human lung and renal mesangial cells is inhibited by 10 nm PGE(2), whereas human gingival fibroblasts are resistant. Ten nm PGE(2) increases cAMP accumulation in lung but not gingival fibroblasts, which require 1 mum PGE(2) to elevate cAMP. Micromolar PGE(2) only slightly reduces the TGFbeta1-stimulated CCN2/CTGF levels in gingival cells. EP2 prostaglandin receptor activation with butaprost blocks the TGFbeta1-stimulated expression of CCN2/CTGF expression in lung, but not gingival, fibroblasts. In lung fibroblasts, inhibition of the TGFbeta1-stimulated CCN2/CTGF by PGE(2), butaprost, or forskolin is due to p38, ERK, and JNK MAP kinase inhibition that is cAMP-dependent. Inhibition of any two MAPKs completely blocks CCN2/CTGF expression stimulated by TGFbeta1. These data mimic the inhibitory effects of 10 nm PGE(2) and forskolin that were dependent on PKA activity. In gingival fibroblasts, the sole MAPK mediating the TGFbeta1-stimulated CCN2/CTGF expression is JNK. Whereas forskolin reduces TGFbeta1-stimulated expression of CCN2/CTGF by 35% and JNK activation in gingival fibroblasts, micromolar PGE(2)-stimulated JNK in gingival fibroblasts and opposes the inhibitory effects of cAMP on CCN2/CTGF expression. Stimulation of the EP3 receptor with sulprostone results in a robust increase in JNK activation in these cells. Taken together, data identify two mechanisms by which TGFbeta1-stimulated CCN2/CTGF levels in human gingival fibroblasts resist down-regulation by PGE(2): (i) cAMP cross-talk with MAPK pathways is limited in gingival fibroblasts; (ii) PGE(2) activation of the EP3 prostanoid receptor stimulates the activation of JNK.
前列腺素E(2)可阻断转化生长因子TGFβ1诱导的肺和肾成纤维细胞中CCN2/结缔组织生长因子（CTGF）的表达。牙龈组织中前列腺素E(2)水平较高，但在纤维化牙龈过度增生中CCN2/CTGF表达却升高。在前列腺素E(2)存在的情况下牙龈成纤维细胞中CCN2/CTGF的表达促使我们比较不同组织来源的成纤维细胞中CCN2/CTGF表达的调控情况。数据表明，10 nM前列腺素E(2)可抑制转化生长因子β1诱导的人肺和肾系膜细胞中CCN2/CTGF的表达，而人牙龈成纤维细胞对此具有抗性。10 nM前列腺素E(2)可增加肺成纤维细胞而非牙龈成纤维细胞中的环磷酸腺苷（cAMP）积累，牙龈成纤维细胞需要1 μM前列腺素E(2)才能升高cAMP。微摩尔浓度的前列腺素E(2)仅略微降低牙龈细胞中转化生长因子β1刺激的CCN2/CTGF水平。用布他前列素激活EP2前列腺素受体可阻断转化生长因子β1刺激的肺成纤维细胞而非牙龈成纤维细胞中CCN2/CTGF的表达。在肺成纤维细胞中，前列腺素E(2)、布他前列素或福斯高林对转化生长因子β1刺激的CCN2/CTGF的抑制作用是由于依赖cAMP的p38、细胞外信号调节激酶（ERK）和应激活化蛋白激酶（JNK）丝裂原活化蛋白激酶（MAPK）的抑制。抑制任何两种MAPK可完全阻断转化生长因子β1刺激的CCN2/CTGF表达。这些数据模拟了依赖蛋白激酶A（PKA）活性的10 nM前列腺素E(2)和福斯高林的抑制作用。在牙龈成纤维细胞中，介导转化生长因子β1刺激的CCN2/CTGF表达的唯一MAPK是JNK。虽然福斯高林可使牙龈成纤维细胞中转化生长因子β1刺激的CCN2/CTGF表达降低35%并抑制JNK激活，但微摩尔浓度的前列腺素E(2)可刺激牙龈成纤维细胞中的JNK并对抗cAMP对CCN2/CTGF表达的抑制作用。用硫前列酮刺激EP3受体可导致这些细胞中JNK激活显著增加。综上所述，数据确定了人牙龈成纤维细胞中转化生长因子β1刺激的CCN2/CTGF水平抵抗前列腺素E(2)下调的两种机制：(i)牙龈成纤维细胞中cAMP与MAPK途径的相互作用有限；(ii)前列腺素E(2)激活EP3类前列腺素受体刺激JNK的激活。
