PPARγ2内源性配体对成骨细胞骨代谢相关基因表达的影响

Influence of peroxisome proliferator activated receptor γ2 endogenous ligands on mRNA expression of bone metabolism related genes in osteoblastic cells

目的探讨PPAR72内源性配体氧化低密度脂蛋白（Ox-LDL）、15脱氧一前列腺素J2（15d—PGJ2）、白三烯B4（LTB4）在骨代谢中的作用。方法体外培养大鼠成骨细胞，分别加入不同浓度Ox—LDL、15d．PGJ2、LTB4干预24h，RT-PCR检测成骨细胞PPARγ2、NF-kB活化受体配体（RANKL）、碱性磷酸酶（ALP）、护骨素mRNA表达水平，分别比较上述3种PPARγ2内源性配体对骨代谢相关基因表达的影响。结果不同浓度Ox-LDL、15d-PGJ2、LTB4均呈剂量依赖性下调成骨细胞RANKL、ALP、护骨素mRNA的表达水平，同时呈剂量依赖性上调PPARγ2 mRNA的表达水平，组间比较差异有统计学意义（P〈0．05或P〈0．01）。结论PPARγ2内源性活化配体Ox-LDL、15d-PGJ2、LTB4可能通过激活PPARγ2转录活性抑制成骨细胞成骨标记物基因的表达，从而参与增龄相关的骨质疏松的发病过程。

Objective To observe the effect of oxidized low-density lipoproteins （Ox-LDL）, 15-Deoxy- △ 12,14.prostaglandin J2 （ 15d-PGJ2 ） , leukotrienes 114 （ LTB4 ） on mRNA expressions of peroxisome proliferator activated receptor γ2 （ PPART2 ）, receptor activator of NF-KB ligand （ RANKL）, alkaline phosphatase （ ALP）, and osteoprotegerin（OPG） in osteoblastic cells of rats; and to investigate the influence of these PPARγ2 endogenous ligands on bone metabolism. Methods Rat osteoblastic cells were cultured in vitro for 24 h in medium with different PPARγ2 endogenous ligands at various concentrations （ the final concentrations of Ox-LDL were 0, 12. 5, 25, 50 μg/ml; the final concentrations of 15d-PGJ2 were 0, 10, 20, 30 μmol/L; the final concentrations of LTB4 were 0, O. 1, 1.0, 10 μmol/L）. RT-PCR was performed to determine the mRNA expressions of PPARγ2, RANKL, ALP, and OPG in osteoblastic cells. Results RT-PCR analysis showed that Ox-LDL, 15d-PGJ2 , and LTB4 all down-regulated the mRNA expressions of RANKL, ALP, and OPG, while up-regulated the mRNA expressions of PPARγ2 in osteoblastic ceils in a dose-dependent manner. Significant differences were found in interclass comparisons（ P〈0. 05 or P〈 0.01 ）. Conclusions These findings suggest that Ox-LDL, 15d-PGJ2, and LTB4 suppress the expressions of osteogenic genes through activating the transcription activity of PPARγ2, and this may be a plausible mechanism of senile osteoporosis.