IRAK-4对成骨细胞分化BMP-Smad通道的影响

目的　探讨白细胞介素-l受体相关激酶-4对成骨细胞分化过程BMP-Smad通道的影响。 方法　 C2C12细胞是肌卫星细胞，不同培养条件下有不同分化潜能。它可分化为成骨细胞，是研究体外成骨细胞分化的理想模型。C2C12细胞培养于培养板中，随机分为3组，每组加入不同培养物，模拟干细胞向成骨细胞分化过程中受到的不同刺激。检测ALP活性、Smad1 mRNA、P-Smad1蛋白表达，观察不同刺激对成骨细胞分化的影响。 结果　与正常对照组比较，BMP-2组ALP活性明显增加，与BMP-2组比，BMP2+IRAK-4siRNA转染组ALP活性增加，BMP2+IRAK-4siRNA转染组和BMP-2组比Smadl 　mRNA的表达只是轻微增加，P-Smad1蛋白表达明显增加。 结论　BMP-2可增强C2C12细胞成骨化，IRAK-4可抑制C2C12细胞被BMP-2诱导的成骨化，其机制可能是通过减弱BMP-Smad通道中Smad1磷酸化水平实现的。

Effect of IRAK-4 on BMP-Smad pathway in osteoblast differentiation

Objective　To study the mechanisms of the effect of IRAK-4 on BMP-Smad pathway in osteoblast differentiation.　Methods　C2C12 are muscle satellite cells isolated from the muscle tissue, which shows a different differentiation potential under different culture conditions. C2C12 cells have the potential of osteoblast cells, and can serve as an ideal model for experiment of osteoblast differentiation. C2C12 cells were cultured in plates and randomly divided into 3 groups; each group was treated with different stimuli to imitate the stimuli in osteoblast differentiation. Cell ALP osteoblastic activity was analyzed by PNNP, Smad1 mRNA expression was detected by RT-PCR, the expression level of P-Smad1 protein was determined by immunohistochemistry and Western blot, to observe the effects of different stimulation on osteoblast differentiation. Results The differentiation of osteoblast ALP activity showed that in the group treated with BMP-2 was significantly higher than that in the control group, the group treated with BMP-2 and IRAK-4siRNA was significantly higher than that treated with BMP-2. RT-PCR results showed that compared with the group that treated with BMP-2, the expression of smad1 mRNA in the group that treated with BMP-2 and IRAK-4siRNA was only slightly increased,but the protein expression was significantly increased. Conclusions BMP-2 can enhance C2C12 cell osteogenic effect. IRAK-4 could inhibit osteogenic effect , which could possibly be the result of reduced BMP-2,Smad1 phosphorylation.