Sato Kan, Yonemura Takashi, Ishii Hiroshi, Toyomizu Masaaki, Kamada Toshihiko, Akiba Yukio
Animal Science, Department of Biological Production, Tokyo University of Agriculture and Technology, Fuchu-shi, Tokyo, 183-8509, Japan.
Comp Biochem Physiol A Mol Integr Physiol. 2009 Nov;154(3):370-5. doi: 10.1016/j.cbpa.2009.07.006. Epub 2009 Jul 18.
The adipocyte differentiation process involves a cascade of transcriptional events that culminates in the expression of peroxisome proliferator-activated receptor (PPAR)gamma. The present study was undertaken to identify the role of PPARbeta/delta in chicken adipocyte differentiation, with experiments performed using a PPARgamma agonist, a PPARbeta/delta agonist, a PPARgamma antagonist and fatty acid (oleate). Preadipocyte cells cultured in a differentiation medium (DMEM containing 500nM dexamethasone, 0.5mM 3-isobutyl-1-methylxanthine, 20microg/mL bovine insulin and 10% fetal bovine serum) supplemented with 200microM oleate resulted in a significant increase in adipocyte fatty acid binding protein (aP2) mRNA expression after 24h and 7d of culture compared to cells cultured in a differentiation medium alone, while supplementation of the differentiation medium with GW501516 (a PPARbeta/delta agonist) did not affect aP2 mRNA expression levels. Supplementation of the differentiation medium with troglitazone (a PPARgamma agonist) and GW501516 induced preadipocyte differentiation; a significant increase of aP2 mRNA expression was observed in cells after incubation for 7d, but not after 24h of incubation. These results suggest that PPARbeta/delta does not play a key role in adipocyte differentiation, but it does enhance the transformation of immature into mature adipocytes in chickens. In addition, oleate functions not only as an activator of PPARs but also induces PPARgamma gene expression via alternative pathway of PPARs activation. These results establish the importance of exogenous fatty acid in the processes of adipogenesis and fat accumulation in chickens.
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（PPAR）γ的表达。本研究旨在确定PPARβ/δ在鸡脂肪细胞分化中的作用，实验使用了PPARγ激动剂、PPARβ/δ激动剂、PPARγ拮抗剂和脂肪酸（油酸）。在含有200μM油酸的分化培养基（含500nM地塞米松、0.5mM 3-异丁基-1-甲基黄嘌呤、20μg/mL牛胰岛素和10%胎牛血清的DMEM）中培养的前脂肪细胞，与仅在分化培养基中培养的细胞相比，培养24小时和7天后，脂肪细胞脂肪酸结合蛋白（aP2）mRNA表达显著增加，而在分化培养基中添加GW501516（一种PPARβ/δ激动剂）不影响aP2 mRNA表达水平。在分化培养基中添加曲格列酮（一种PPARγ激动剂）和GW501516可诱导前脂肪细胞分化；孵育7天后细胞中观察到aP2 mRNA表达显著增加，但孵育24小时后未观察到。这些结果表明，PPARβ/δ在脂肪细胞分化中不发挥关键作用，但它确实促进了鸡体内未成熟脂肪细胞向成熟脂肪细胞的转化。此外，油酸不仅作为PPARs的激活剂发挥作用，还通过PPARs激活的替代途径诱导PPARγ基因表达。这些结果确立了外源性脂肪酸在鸡脂肪生成和脂肪积累过程中的重要性。
