Lipopolysaccharide (LPS) Induces the Apoptosis and Inhibits Osteoblast Differentiation Through JNK Pathway in MC3T3-E1 Cells
Lipopolysaccharide (LPS) Induces the Apoptosis and Inhibits Osteoblast Differentiation Through JNK Pathway in MC3T3-E1 Cells
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脂多糖（LPS）通过 JNK 途径诱导 MC3T3-E1 细胞凋亡并抑制成骨细胞分化。
DOI：
10.1007/s10753-013-9778-9
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发表时间：
2014-04-01
期刊：
影响因子：
5.1
通讯作者：
Song, Guo-hua
中科院分区：
文献类型：
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作者：
Guo, Chun;Yuan, Lei;Song, Guo-hua
骨退化是慢性炎症性疾病的严重并发症，如感染性关节炎、骨髓炎和感染性骨科植入物失败。迄今为止，对细菌引起的骨破坏的有效治疗方法是有限的。在我们之前的研究中，我们发现LPS通过激活丝裂原活化蛋白激酶（MAPKs）途径，如c-Jun n-末端激酶（JNK）和细胞外信号调节激酶（ERK1/2），促进破骨细胞的分化和活性。本研究旨在探讨LPS对MC3T3-E1细胞凋亡和成骨细胞分化的影响机制。MC3T3-E1成骨细胞未处理，LPS处理。处理后测定细胞活力、碱性磷酸酶（ALP）和caspase-3活性。采用实时定量聚合酶链反应（qPCR）检测成骨细胞特异性基因Bax、Bcl-2、caspase-3的表达。采用Western blotting检测Bax、Bcl-2、caspase-3蛋白水平和MAPKs磷酸化水平。JNK抑制剂SP600125预处理可阻断MAPK信号通路。LPS处理导致MC3T3-E1细胞代谢、活力和ALP活性显著降低。LPS还显著降低MC3T3-E1细胞成骨相关基因mRNA的表达。另一方面，LPS显著上调MC3T3-E1细胞中Bax和caspase-3的mRNA表达和蛋白水平以及caspase-3的激活，而降低Bcl-2的表达。此外，LPS显著促进MAPK通路，包括JNK磷酸化和ERK1/2磷酸化；此外，JNK抑制剂预处理不仅可以减弱LPS在MC3T3-E1细胞中增强的磷酸化-JNK和ERK1/2，还可以逆转LPS诱导的ALP和BSP等成骨特异性基因的下调表达。综上所述，LPS可通过激活JNK通路诱导成骨细胞凋亡，抑制成骨细胞分化。
Bone degradation is a serious complication of chronic inflammatory diseases such as septic arthritis, osteomyelitis, and infected orthopedic implant failure. Up to date, effective therapeutic treatments for bacteria-caused bone destruction are limited. In our previous study, we found that LPS promoted osteoclast differentiation and activity through activation of mitogen-activated protein kinases (MAPKs) pathway such as c-Jun N-terminal kinases (JNK) and extracellular signal regulated kinase (ERK1/2). The current study was to evaluate the mechanism of LPS on the apoptosis and osteoblast differentiation in MC3T3-E1 cells. MC3T3-E1 osteoblasts were non-treated, treated with LPS. After treatment, the cell viability, the activity of alkaline phosphatase (ALP) and caspase-3 were measured. The expressions of osteoblast-specific genes and Bax, Bcl-2, and caspase-3 were determined by real-time quantitative polymerase chain reaction (qPCR). Protein levels of Bax, Bcl-2, caspase-3, and phosphorylation of MAPKs were measured using Western blotting assays. The MAPK signaling pathway was blocked by pretreatment with JNK inhibitor SP600125. LPS treatment induced a significant decrease in cell metabolism, viability, and ALP activity in MC3T3-E1 cells. LPS also significantly decreased mRNA expressions of osteoblast-related genes in MC3T3-E1 cells. On the other hand, LPS significantly upregulated mRNA expressions and protein levels of Bax and caspase-3 as well as activation of caspase-3, whereas decreased Bcl-2 expression in MC3T3-E1 cells. Furthermore, LPS significantly promoted MAPK pathway including the phosphorylation of JNK and the phosphorylation of ERK1/2; moreover, pretreatment with JNK inhibitor not only attenuated both of phosphorylation-JNK and ERK1/2 enhanced by LPS in MC3T3-E1 cells, but also reversed the downregulated expressions of osteoblast-specific genes including ALP and BSP induced by LPS. In conclusion, LPS could induce osteoblast apoptosis and inhibit osteoblast differentiation via activation of JNK pathway.