Laboratory of Biodefense and Regulation, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan.
PLoS One. 2012;7(9):e44698. doi: 10.1371/journal.pone.0044698. Epub 2012 Sep 7.
We recently reported that aldo-keto reductase 1B3-produced prostaglandin (PG) F(2α) suppressed the early phase of adipogenesis. PGE(2) is also known to suppress adipogenesis. In this study, we found that microsomal PGE(2) synthase (PGES)-1 (mPGES-1; PTGES1) acted as the PGES in adipocytes and that PGE(2) and PGF(2α) synergistically suppressed the early phase of adipogenesis. PGE(2) production was detected in preadipocytes and transiently enhanced at 3 h after the initiation of adipogenesis of mouse adipocytic 3T3-L1 cells, followed by a quick decrease; and its production profile was similar to the expression of the cyclooxygenase-2 (PTGS2) gene. When 3T3-L1 cells were transfected with siRNAs for any one of the three major PTGESs, i.e., PTGES1, PTGES2 (mPGES-2), and PTGES3 (cytosolic PGES), only PTGES1 siRNA suppressed PGE(2) production and enhanced the expression of adipogenic genes. AE1-329, a PTGER4 (EP4) receptor agonist, increased the expression of the Ptgs2 gene with a peak at 1 h after the initiation of adipogenesis. PGE(2)-mediated enhancement of the PTGS2 expression was suppressed by the co-treatment with L-161982, a PTGER4 receptor antagonist. Moreover, AE1-329 enhanced the expression of the Ptgs2 gene by binding of the cyclic AMP response element (CRE)-binding protein to the CRE of the Ptgs2 promoter; and its binding was suppressed by co-treatment with L-161982, which was demonstrated by promoter luciferase and chromatin immunoprecipitation assays. Furthermore, when 3T3-L1 cells were caused to differentiate into adipocytes in medium containing both PGE(2) and PGF(2α), the expression of the adipogenic genes and the intracellular triglyceride level were decreased to a greater extent than in medium containing either of them, revealing that PGE(2) and PGF(2α) independently suppressed adipogenesis. These results indicate that PGE(2) was synthesized by PTGES1 in adipocytes and synergistically suppressed the early phase of adipogenesis of 3T3-L1 cells in cooperation with PGF(2α) through receptor-mediated activation of PTGS2 expression.
我们最近报道称，醛酮还原酶 1B3 产生的前列腺素 (PG) F(2α) 抑制了脂肪生成的早期阶段。已知 PGE(2) 也能抑制脂肪生成。在这项研究中，我们发现微粒体 PGE(2) 合酶 (PGES)-1 (mPGES-1; PTGES1) 在脂肪细胞中作为 PGES 发挥作用，并且 PGE(2) 和 PGF(2α) 协同抑制脂肪生成的早期阶段。在小鼠脂肪细胞 3T3-L1 细胞的脂肪生成起始后 3 小时检测到 PGE(2) 的产生，并迅速降低；其产生谱与环氧化酶-2 (PTGS2) 基因的表达相似。当 3T3-L1 细胞用任何一种三种主要的 PTGES 即 PTGES1、PTGES2 (mPGES-2) 和 PTGES3 (胞质 PGES) 的 siRNA 转染时，只有 PTGES1 siRNA 抑制 PGE(2) 的产生并增强脂肪生成基因的表达。AE1-329，一种 PTGER4 (EP4) 受体激动剂，在脂肪生成起始后 1 小时增加 Ptgs2 基因的表达，达到峰值。PGE(2) 介导的 PTGS2 表达增强被 PTGER4 受体拮抗剂 L-161982 共同处理所抑制。此外，AE1-329 通过 cAMP 反应元件 (CRE)-结合蛋白与 Ptgs2 启动子的 CRE 结合来增强 Ptgs2 基因的表达；并且其结合被 L-161982 共同处理所抑制，这通过启动子荧光素酶和染色质免疫沉淀测定来证明。此外，当 3T3-L1 细胞在含有 PGE(2) 和 PGF(2α) 的培养基中分化为脂肪细胞时，脂肪生成基因的表达和细胞内甘油三酯水平降低的程度大于在仅含有其中一种培养基的情况下，表明 PGE(2) 和 PGF(2α) 独立抑制脂肪生成。这些结果表明，PGE(2) 是由脂肪细胞中的 PTGES1 合成的，并通过与 PGF(2α) 协同作用通过受体介导的 PTGS2 表达激活来协同抑制 3T3-L1 细胞脂肪生成的早期阶段。
