Matsubara Yusuke, Sato Kan, Ishii Hiroshi, Akiba Yukio
Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.
Comp Biochem Physiol A Mol Integr Physiol. 2005 May;141(1):108-15. doi: 10.1016/j.cbpb.2005.04.013.
The adipocyte differentiation process involves a cascade of transcriptional events that culminates in the expression of peroxisome proliferator-activated receptor-gamma (PPARgamma) and CCAAT/enhancer binding protein-alpha (C/EBPalpha). These adipogenic transcription factors regulate the expression of genes necessary for the development of mature adipocytes in mammals. The current study was undertaken to identify regulatory factors that affect adipogenesis and to analyze species-specific mRNA expression of factors involved in chicken adipocyte differentiation. We developed a system for differentiation of chicken (Gallus gallus) adipocytes in culture using medium containing 500 nM dexamethasone, 0.5 mM 3-isobutyl-1-methylxanthine, 20 microg/mL bovine insulin, 300 microM oleate, and 10% fetal bovine serum. The rapid differentiation of cells to mature adipocytes in this culture system was verified by observed increases in adipocyte fatty acid-binding protein (aP2) expression, glycerol-3-phosphate dehydrogenase (GPDH) activity and intracellular triglyceride accumulation. In contrast, cells cultured in a differentiation medium without fatty acids did not differentiate into mature adipocytes. The expression profiles of genes involved in the regulation of adipocyte differentiation, such as PPARgamma, C/EBPalpha, beta, delta, sterol regulatory element binding protein-1 (SREBP-1), fatty acid synthase (FAS), lipoprotein lipase (LPL), and glucose transporters 1 and 8 (GLUT1 and GLUT8) were studied. Rapid increases in PPARgamma and aP2 expression were observed after 9 and 12 h of culture in differentiation medium, respectively. In contrast, the expression patterns of the other adipogenic genes only differed slightly from those previously determined for mammalian adipocytes. These results suggest that exogenous fatty acid is essential for adipocyte differentiation in chickens, and that PPARgamma is possibly a key regulator in the early stages of chicken preadipocyte differentiation.
脂肪细胞分化过程涉及一系列转录事件，最终导致过氧化物酶体增殖物激活受体γ（PPARγ）和CCAAT/增强子结合蛋白α（C/EBPα）的表达。这些脂肪生成转录因子调节哺乳动物成熟脂肪细胞发育所需基因的表达。本研究旨在确定影响脂肪生成的调控因子，并分析参与鸡脂肪细胞分化的因子的物种特异性mRNA表达。我们开发了一种在含有500 nM地塞米松、0.5 mM 3-异丁基-1-甲基黄嘌呤、20 μg/mL牛胰岛素、300 μM油酸和10%胎牛血清的培养基中培养鸡（原鸡）脂肪细胞分化的系统。通过观察脂肪细胞脂肪酸结合蛋白（aP2）表达的增加、甘油-3-磷酸脱氢酶（GPDH）活性和细胞内甘油三酯积累，证实了该培养系统中细胞能快速分化为成熟脂肪细胞。相比之下，在不含脂肪酸的分化培养基中培养的细胞未分化为成熟脂肪细胞。研究了参与脂肪细胞分化调控的基因的表达谱，如PPARγ、C/EBPα、β、δ、固醇调节元件结合蛋白-1（SREBP-1）、脂肪酸合酶（FAS）、脂蛋白脂肪酶（LPL）以及葡萄糖转运蛋白1和8（GLUT1和GLUT8）。在分化培养基中培养9小时和12小时后，分别观察到PPARγ和aP2表达迅速增加。相比之下，其他脂肪生成基因的表达模式与先前确定的哺乳动物脂肪细胞的表达模式仅略有不同。这些结果表明，外源性脂肪酸对鸡脂肪细胞分化至关重要，并且PPARγ可能是鸡前脂肪细胞分化早期的关键调节因子。
