TY - JOUR
T1 - 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
AU - He, W
AU - Qu, T
AU - Yu, Q
AU - Wang, Z
AU - Wang, H
AU - Zhang, J
AU - Smith, Anthony
PY - 2012/4/1
Y1 - 2012/4/1
N2 - 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-kappa B), 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 NE-kappa B or I Kappa B alpha (I kappa B alpha) significantly inhibited LPS-induced DCN expression. Moreover, the LPS-mediated increase in kappa B-luciferase activity in OLCs was suppressed by the overexpression of dominant negative mutants of TLR4, MyD88, and I kappa B alpha 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-kappa B, and MAPK pathways in odontoblast cells. (J Endod 2012;38:464-469)
AB - 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-kappa B), 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 NE-kappa B or I Kappa B alpha (I kappa B alpha) significantly inhibited LPS-induced DCN expression. Moreover, the LPS-mediated increase in kappa B-luciferase activity in OLCs was suppressed by the overexpression of dominant negative mutants of TLR4, MyD88, and I kappa B alpha 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-kappa B, and MAPK pathways in odontoblast cells. (J Endod 2012;38:464-469)
KW - odontoblasts
KW - NF-kappa B
KW - lipopolysaccharide
KW - TLR4
KW - Decorin
KW - mitogen-activated protein kinase
U2 - 10.1016/j.joen.2011.12.021
DO - 10.1016/j.joen.2011.12.021
M3 - Article
C2 - 22414830
VL - 38
SP - 464
EP - 469
JO - Journal of Endodontics
JF - Journal of Endodontics
IS - 4
ER -