脂多糖通过 Toll 样受体 4、髓样分化因子 88、核因子-κB 和丝裂原活化蛋白激酶通路增强成牙本质细胞中核心蛋白聚糖的表达。
Lipopolysaccharide enhances decorin expression through the Toll-like receptor 4, myeloid differentiating factor 88, nuclear factor-kappa B, and mitogen-activated protein kinase pathways in odontoblast cells.
机构信息
Department of Conservative Dentistry, School of Dentistry, The Fourth Military Medical University, Xian, China.
出版信息
J Endod. 2012 Apr;38(4):464-9. doi: 10.1016/j.joen.2011.12.021. Epub 2012 Jan 31.
INTRODUCTION
Lipopolysaccharide (LPS) has been shown to regulate the function of odontoblasts. However, the molecular mechanisms of the effect of LPS on odontoblasts are poorly understood. Decorin (DCN), one of the major matrix proteoglycans, is known to affect the mineralization of teeth. In this study, we investigated whether LPS can regulate the expression of DCN in odontoblasts and determined the intracellular signaling pathways triggered by LPS.
METHODS
The DCN messenger RNA and protein expression changes in mouse odontoblast-lineage cells (OLCs) were detected by real-time polymerase chain reaction (PCR) analysis and enzyme-linked immunosorbent assay (ELISA). Whether TLR4, myeloid differentiating factor 88 (MyD88), nuclear factor-kappa B (NF-κB), or mitogen-activated protein kinase (MAPK) pathways were involved in the LPS-induced DCN expression was determined by examined real-time PCR, ELISA, and luciferase activity assay. The activation of extracellular signal-regulated kinase (ERK), p38, and JNK in OLCs was measured by Western blot analysis.
RESULTS
We found that the mouse OLCs expressed DCN. DCN messenger RNA was rapidly induced by LPS in a time- and dose-dependent manner. Pretreatment with a MyD88 inhibitory peptide, a TLR4 antibody, or a specific inhibitor for NF-κB or I Kappa B alpha (IκBα) significantly inhibited LPS-induced DCN expression. Moreover, the LPS-mediated increase in κB-luciferase activity in OLCs was suppressed by the overexpression of dominant negative mutants of TLR4, MyD88, and IκBα but not by a dominant negative mutant of TLR2. In addition, LPS stimulation activated the ERK, p38, and JNK MAPK pathways. The pretreatment of OLCs with specific inhibitors of the ERK, p38, and JNK MAPK pathways markedly offset the LPS-induced up-regulation of DCN expression.
CONCLUSIONS
Our results show that LPS stimulation can up-regulate the gene expression of DCN via the TLR4, MyD88, NF-κB, and MAPK pathways in odontoblast cells.
简介
脂多糖（LPS）已被证明可调节成牙本质细胞的功能。然而，LPS 对成牙本质细胞影响的分子机制尚不清楚。核心蛋白聚糖（DCN）是主要的基质蛋白聚糖之一，已知其可影响牙齿矿化。在这项研究中，我们研究了 LPS 是否可以调节成牙本质细胞中 DCN 的表达，并确定了 LPS 触发的细胞内信号通路。
方法
通过实时聚合酶链反应（PCR）分析和酶联免疫吸附测定（ELISA）检测小鼠成牙本质细胞系（OLC）中 DCN 的信使 RNA 和蛋白表达变化。通过实时 PCR、ELISA 和荧光素酶活性测定，研究了 TLR4、髓样分化因子 88（MyD88）、核因子-κB（NF-κB）或丝裂原活化蛋白激酶（MAPK）通路是否参与 LPS 诱导的 DCN 表达。通过 Western blot 分析测量 OLC 中细胞外信号调节激酶（ERK）、p38 和 JNK 的激活。
结果
我们发现小鼠 OLC 表达 DCN。DCN 信使 RNA 被 LPS 快速诱导，呈时间和剂量依赖性。用 MyD88 抑制肽、TLR4 抗体或 NF-κB 或 IκBα（IκBα）的特定抑制剂预处理可显著抑制 LPS 诱导的 DCN 表达。此外，用 TLR4、MyD88 和 IκBα的显性负突变体而非 TLR2 的显性负突变体抑制 OLC 中κB-荧光素酶活性的 LPS 介导的增加。此外，LPS 刺激激活了 ERK、p38 和 JNK MAPK 通路。用 ERK、p38 和 JNK MAPK 通路的特定抑制剂预处理 OLC 可显著抵消 LPS 诱导的 DCN 表达上调。
结论
我们的结果表明，LPS 刺激可通过 TLR4、MyD88、NF-κB 和 MAPK 通路在上皮细胞中上调 DCN 的基因表达。
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