细胞外信号调节激酶丝裂原活化蛋白激酶和磷脂酰肌醇3-激酶/蛋白激酶B信号通路是脂多糖介导的小鼠成牙本质细胞样细胞矿化所必需的。
Extracellular Signal-regulated Kinase Mitogen-activated Protein Kinase and Phosphatidylinositol 3-Kinase/Akt Signaling Are Required for Lipopolysaccharide-mediated Mineralization in Murine Odontoblast-like Cells.
作者信息
Wang Zhihua, Ma Fengle, Wang Juan, Zhou Zeyuan, Liu Baogang, He Xinyao, Fu Lei, He Wenxi, Cooper Paul R
机构信息
State Key Laboratory of Military Stomatology, Department of Operative Dentistry and Endodontics, School of Stomatology, Fourth Military Medical University, Xi'an, PR China.
Department of Stomatology, Lishilu Outpatient Department, Chinese PLA Second Artillery Corps, Beijing, PR China.
出版信息
J Endod. 2015 Jun;41(6):871-6. doi: 10.1016/j.joen.2015.01.006. Epub 2015 Feb 24.
INTRODUCTION
Odontoblasts play an important role in post-developmental control of mineralization in response to external stimuli in the tooth. The present study investigated whether lipopolysaccharide (LPS), a major bacterial cell wall component, influenced mineralization in a murine odontoblast-like cell (OLC) line and the related intracellular signaling pathways involved.
METHODS
Alizarin red S staining was used to assess mineralized nodule formation in OLCs in response to LPS. The effects of LPS on gene expression of odontoblastic markers were investigated by using quantitative real-time reverse-transcriptase polymerase chain reaction. The potential involvement of toll-like receptor 4 (TLR4), nuclear factor kappa B (NF-κB), mitogen-activated protein kinase (MAPK), or phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways in the mineralized nodule formation, and mRNA expression of several odontoblastic markers of OLCs induced by LPS was assessed by using alizarin red S staining and quantitative real-time reverse-transcriptase polymerase chain reaction. Moreover, LPS stimulation resulted in phosphorylation of protein that was determined by Western blot analysis.
RESULTS
OLCs showed reduced mineralized nodule formation and several odontoblastic markers expression in response to LPS exposure. Furthermore, inhibition of TLR4, extracellular signal-regulated kinase (ERK), and PI3K/Akt signaling noticeably antagonized LPS-mediated mineralization in OLCs. However, p38 MAPK, c-Jun N-terminal kinase, and NF-κB signaling inhibitors did not affect LPS-mediated mineralization in OLCs. Notably, LPS treatment resulted in a time-dependent phosphorylation of ERK and PI3K/Akt in OLCs, which was abrogated by their specific inhibitors.
CONCLUSIONS
LPS decreased mineralization in OLCs via TLR4, ERK MAPK, and PI3K/Akt signaling pathways, but not p38, c-Jun N-terminal kinase, or NF-κB signaling.
引言
成牙本质细胞在牙齿发育后对外部刺激的矿化控制中发挥着重要作用。本研究调查了细菌细胞壁的主要成分脂多糖（LPS）是否影响小鼠成牙本质细胞样细胞（OLC）系中的矿化以及相关的细胞内信号通路。
方法
使用茜素红S染色评估OLC中对LPS反应的矿化结节形成。通过定量实时逆转录聚合酶链反应研究LPS对成牙本质细胞标志物基因表达的影响。使用茜素红S染色和定量实时逆转录聚合酶链反应评估Toll样受体4（TLR4）、核因子κB（NF-κB）、丝裂原活化蛋白激酶（MAPK）或磷脂酰肌醇3激酶（PI3K）/Akt信号通路在矿化结节形成中的潜在参与以及LPS诱导的OLC的几种成牙本质细胞标志物的mRNA表达。此外，通过蛋白质印迹分析确定LPS刺激导致的蛋白质磷酸化。
结果
OLC在暴露于LPS时显示矿化结节形成减少和成牙本质细胞标志物表达降低。此外，抑制TLR4、细胞外信号调节激酶（ERK）和PI3K/Akt信号明显拮抗OLC中LPS介导的矿化。然而，p38 MAPK、c-Jun N末端激酶和NF-κB信号抑制剂不影响OLC中LPS介导的矿化。值得注意的是，LPS处理导致OLC中ERK和PI3K/Akt的时间依赖性磷酸化，这被其特异性抑制剂所消除。
结论
LPS通过TLR4、ERK MAPK和PI3K/Akt信号通路降低OLC中的矿化，但不通过p38、c-Jun N末端激酶或NF-κB信号通路。
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