网膜素对成骨细胞向钙化血管平滑肌细胞分化的影响及其机理

Effect and mechanism of omentin on the differentiation of osteoblasts into calcifying vascular smooth muscle cells

目的探讨网膜素对成骨细胞向钙化血管平滑肌细胞(CVSMCs)分化的影响。方法网膜素处理VSMCs细胞,用茜素红S染色确定基质矿化范围,用PCR探测碱性磷酸酶(ALP)及骨钙素表达,免疫印迹分析MAPK和Akt活性。结果网膜素剂量依耐性抑制CVSMCs ALP及骨钙素mRNA转录(P<0.05);与对照组比较,100 ng/ml,500 ng/ml及1000 ng/ml网膜素分别降低茜素红染色22%、41%及85%(P<0.05);网膜素时间依耐性提高CVSMCs Akt活性(P<0.05),对ERK、p38及JNK无影响;网膜素对VSMCs细胞内c AMP生成无明显影响。细胞用LY294002或HIMO处理后,网膜素对ALP活性及基质矿化的影响被消除了。结论本研究结果首次表明网膜素通过PI3K/Akt途径抑制成骨细胞分化为CVSMCs,表明肥胖者网膜素降低会促进动脉钙化的发展,网膜素有抑制动脉钙化的作用。

Objective To investigate the effect of omentin on the differentiation of osteoblasts into calcifying vascular smooth muscle cells （CVSMCs）. Methods VSMCs were treated with omentin. The extent of matrix mineralization was determined using Alizarin red staining. The mRNA expression of alkaline phosphatase （ALP） and osteocalcin was assayed using real-time quantitative RT-PCR. The MAPK and Akt activation were detected using Western blot analysis. Results Omentin dose-dependently inhibited the expression of ALP and osteocalcin mRNA （P 〈 0. 05）. Compared with the control group, omentin of 100 ng/ml, 500 ng/ml, and 1000ng/ml decreased Alizarin Red S staining by 22%, 41% , and 85% respectively （P 〈 0.05）. Omentin time-dependently increased the activity of Akt in CVSMCs （ P 〈 0.05 ）, but had no effect on the activity of ERK, p38, and JNK. It also had no effect on intracellutar cAMP generation. Treatment of cells with LY294002 or HIMO abolished the inhibitory effect of omentin on ALP activity and the matrix mineralization. Conclusion The present results demonstrate for the first time that omentin can inhibit differentiation of osteoblasts CVSMCs into via PI3K/Akt signaling pathway, suggesting that the lower omentin levels in obese subjects contribute to the development of arterial calcification, and omentin plays a protective role against arterial calcification.