Xie Y, Kang X, Ackerman W E, Belury M A, Koster C, Rovin B H, Landon M B, Kniss D A
Department of Obstetrics and Gynecology, Laboratory of Perinatal Research, The Ohio State University, College of Medicine and Public Health, Columbus, OH 43210, USA.
Diabetes Obes Metab. 2006 Jan;8(1):83-93. doi: 10.1111/j.1463-1326.2005.00472.x.
A thorough understanding of the mechanisms of adipocyte differentiation and metabolism is important for the prevention and/or treatment of obesity and its complications, including type 2 diabetes mellitus. A complex role for prostaglandins (PGs) in adipogenesis is suggested. We examined the expression and cellular localization of enzymes in the cyclooxygenase (COX) cascade that synthesize PGs as well as the PG profile as a function of differentiation status in 3T3-L1 cells.
Murine 3T3-L1 preadipocytes were used as a model for studies of adipocyte differentiation induced by a hormone cocktail and compared with the parental fibroblastic line NIH 3T3. Both cell lines were incubated in maintenance medium or differentiation medium. Nine days after differentiation, the expression of enzymes in the COX cascade was evaluated by immunoblot analysis, reverse transcriptase-polymerase chain reaction (RT-PCR) and immunocytochemistry, and PG formation was examined using enzyme immunoassay.
A differentiation-dependent diminution of COX-1 and COX-2 mRNA and cognate proteins in 3T3-L1 cells was observed. PG release, including PGE(2), 6-keto PGF(1alpha), PGD(2) and 15d-PGJ(2), significantly decreased following differentiation in 3T3-L1 cells (anova/Tukey, p < 0.05). However, microsomal PGE synthase (mPGES) and lipocalin-type PGD synthase (L-PGDS) were selectively upregulated. Immunocytochemistry revealed that COX-1 and COX-2 became intracellularly more diffuse upon differentiation, whereas mPGES was redistributed to the nuclear compartment.
Regulation of PG formation and COX-2 expression in 3T3-L1 cells is differentiation-dependent and involves changes in the levels of gene expression of the individual isoforms as well as redistribution of the enzymes within cellular compartments.
深入了解脂肪细胞分化和代谢机制对于预防和/或治疗肥胖症及其并发症（包括2型糖尿病）至关重要。有研究表明前列腺素（PGs）在脂肪生成中发挥复杂作用。我们研究了在3T3-L1细胞中，合成PGs的环氧化酶（COX）级联反应中各种酶的表达及细胞定位，以及PG谱随分化状态的变化。
将小鼠3T3-L1前脂肪细胞作为激素鸡尾酒诱导脂肪细胞分化的研究模型，并与亲本成纤维细胞系NIH 3T3进行比较。两种细胞系均在维持培养基或分化培养基中培养。分化9天后，通过免疫印迹分析、逆转录聚合酶链反应（RT-PCR）和免疫细胞化学评估COX级联反应中酶的表达，并使用酶免疫测定法检测PG的生成。
在3T3-L1细胞中观察到COX-1和COX-2 mRNA及相关蛋白的表达随分化而减少。3T3-L1细胞分化后，包括PGE(2)、6-酮PGF(1α)、PGD(2)和15d-PGJ(2)在内的PG释放显著减少（方差分析/土耳其检验，p < 0.05）。然而，微粒体PGE合酶（mPGES）和脂质运载蛋白型PGD合酶（L-PGDS）被选择性上调。免疫细胞化学显示，分化后COX-1和COX-2在细胞内的分布更分散，而mPGES重新分布到核区室。
3T3-L1细胞中PG生成和COX-2表达的调节依赖于分化，涉及各个同工型基因表达水平的变化以及酶在细胞区室内的重新分布。
