Department of Cell and Tissue Biology, School of Medicine, Keio University, Tokyo 160-8582, Japan ; Department of Microbiology and Immunology, School of Medicine, Keio University, Tokyo 160-8582, Japan.
PPAR Res. 2013;2013:186312. doi: 10.1155/2013/186312. Epub 2013 Jan 3.
While an understanding of lipid metabolism in chickens is critical for a further improvement of food production, there are few studies concerning differences in lipid metabolism mechanisms between chickens and other species at a molecular level. Chickens have three PPAR gene subtypes (α, β, and γ) that function differently from those present in humans and mice. The chicken PPAR-gamma (cPPARγ) gene is shorter than that in humans and lacks a γ2 isoform. Moreover, in serum-free media, cPPARγ shows high transcriptional activity without exogenous ligands. Luciferase reporter assays were used to examine the effect of sera on cPPAR transcriptional activities and showed that adult bovine serum and chicken serum highly activate cPPARα and β functions. Moreover, we found that bezafibrate induces the transactivation function of cPPARβ, but not human PPARδ (human PPARβ ortholog). This ligand selectivity relies on one amino acid residue (chicken: Val419, human: Met444). These results show the possibilities for unique functions of cPPARs on chicken-specific lipid glucose metabolism. As such, a better understanding of the molecular mechanisms of lipid metabolism in chickens could result in higher productivity for the poultry industry.
虽然了解鸡的脂质代谢对于进一步提高食品生产至关重要，但在分子水平上研究鸡与其他物种之间脂质代谢机制的差异的研究很少。鸡有三种 PPAR 基因亚型（α、β 和 γ），其功能与人类和小鼠中的不同。鸡的 PPAR-γ（cPPARγ）基因比人类的短，并且缺乏 γ2 同工型。此外，在无血清培养基中，cPPARγ 在没有外源性配体的情况下表现出高转录活性。荧光素酶报告基因分析用于研究血清对 cPPAR 转录活性的影响，结果表明，牛血清和鸡血清均能高度激活 cPPARα 和β的功能。此外，我们发现 bezafibrate 诱导 cPPARβ 的反式激活功能，但不诱导人 PPARδ（人 PPARβ 同源物）。这种配体选择性依赖于一个氨基酸残基（鸡：Val419，人：Met444）。这些结果表明 cPPAR 可能在鸡特有的脂质葡萄糖代谢中具有独特的功能。因此，更好地了解鸡的脂质代谢的分子机制可以提高家禽业的生产力。
