Jackson B A, Goldstein R H, Roy R, Cozzani M, Taylor L, Polgar P
Boston University School of Medicine, MA.
Biochem Biophys Res Commun. 1993 Dec 30;197(3):1465-74. doi: 10.1006/bbrc.1993.2642.
Experiments were conducted to determine the roles of the rate limiting enzymes, cyclooxygenase 1 and 2 (COX1 and COX2) and cytoplasmic phospholipase A2 (PLA2), in transforming growth factor beta (TGF-beta) and interleukin-1 (IL-1 beta) activated prostaglandin synthesis. Results show that TGF-beta increases steady state levels of COX1 mRNA in both human embryo lung fibroblasts (IMR90) and calf pulmonary artery endothelial cells (BPAEC). Temporal experiments show that TGF-beta increases, within 2hrs, a 5.5kb COX1 in IMR90 and the 2.7kb COX1 mRNA in BPAEC. IL-1 beta increases COX1 mRNA only in IMR-90, not BPAEC. COX2 mRNA, under basal conditions, is not detected in BPAEC and is expressed only marginally in IMR90. TGF-beta or IL-1 beta have no effect on expression of COX2 gene in either cell type. IL-1 beta increases steady state levels of PLA2 mRNA in both IMR90 and BPAEC while TGF-beta increases expression of the PLA2 gene only in BPAEC. Time experiments with TGF-beta show induction of PLA2 mRNA within 1hr, peaking at 4hrs. PG synthesis in response to the cytokines was determined in IMR90 and BPAEC to further assess the significance of the above results. TGF-beta increases the synthesis of prostacyclin in BPAEC in a time related fashion peaking at 8hrs at 13 fold above basal. To focus on the action of COX1 and bypass the action of PLA2, exogenous arachidonic acid was used as substrate for PG synthesis. In these experiments IL-1 beta increases PGE2 synthesis 8 fold in IMR90 while IL-1 beta and TGF-beta added simultaneously increases PGE2 synthesis 25 fold. These results in sum illustrate that the cytokines, TGF-beta and IL-1 beta, regulate both COX1 and PLA2 mRNA levels. Furthermore, this regulation appears coordinated to bring about elevation of prostaglandin synthesis.
进行实验以确定限速酶环氧合酶1和2（COX1和COX2）以及细胞质磷脂酶A2（PLA2）在转化生长因子β（TGF-β）和白细胞介素-1（IL-1β）激活的前列腺素合成中的作用。结果显示，TGF-β可增加人胚肺成纤维细胞（IMR90）和小牛肺动脉内皮细胞（BPAEC）中COX1 mRNA的稳态水平。时间实验表明，TGF-β在2小时内可使IMR90中的5.5kb COX1和BPAEC中的2.7kb COX1 mRNA增加。IL-1β仅在IMR-90中增加COX1 mRNA，而在BPAEC中则无此作用。在基础条件下，BPAEC中未检测到COX2 mRNA，其在IMR90中仅微量表达。TGF-β或IL-1β对两种细胞类型中COX2基因的表达均无影响。IL-1β可增加IMR90和BPAEC中PLA2 mRNA的稳态水平，而TGF-β仅在BPAEC中增加PLA2基因的表达。TGF-β的时间实验显示，1小时内可诱导PLA2 mRNA，4小时达到峰值。在IMR90和BPAEC中测定了对细胞因子的PG合成反应，以进一步评估上述结果的意义。TGF-β以时间相关方式增加BPAEC中前列环素的合成，8小时达到峰值，比基础水平高13倍。为了关注COX1的作用并绕过PLA2的作用，使用外源性花生四烯酸作为PG合成的底物。在这些实验中，IL-1β使IMR90中的PGE2合成增加8倍，而同时添加IL-1β和TGF-β可使PGE2合成增加25倍。这些结果总体表明，细胞因子TGF-β和IL-1β可调节COX1和PLA2 mRNA水平。此外，这种调节似乎是协调的，以导致前列腺素合成的升高。
