Identification of switching factor that determinates life and death of human dental pulp cells

阿南达胺(AEA)可触发细胞凋亡。本研究旨在探讨其受体在乙酸乙酯诱导人牙髓细胞(HPC)凋亡中的作用及其信号转导途径。AEA可明显诱导HPC凋亡。CB2拮抗剂和VR1拮抗剂均可抑制AEA诱导的细胞死亡。一种细胞外信号调节激酶(ERKs)的抑制剂显著地阻止了HPC细胞的死亡。ERK抑制剂和CB2拮抗剂可抑制AEA调节的核因子-kappaB(NF-κB)激活。此外，针对NF-κB亚单位的特异性siRNA(p50和p65)可抑制AEA诱导的HPC细胞死亡。在这一点上，AEA诱导的牙髓细胞凋亡是通过NF-κB依赖和非依赖的途径来调节的，底物P(SP)诱导与牙髓炎症有关的促炎细胞因子的表达，如白介素6(IL-6)。为了确定SP诱导IL-6的信号通路，我们检测了人牙髓细胞(PF-10)中丝裂原活化蛋白激酶(MAPKs)的活性。SP可在5min内诱导p38MAPK的磷酸化，这种激活可持续至40min，且不依赖于SP刺激PF-10细胞后诱导的细胞外信号相关蛋白(ERK-1和ERK-2)的激活。凝胶迁移率改变分析显示，p38MAPK不参与SP诱导的核因子-kappaB(NF-κB)的激活。然而，p38MAPK介导了SP诱导的IL-6的产生，这一点可以通过使用该激酶的特异性抑制剂来证明。我们的结果提示，p38MAPK的激活对于非NF-κB调节牙髓组织神经源性炎症具有重要意义。

Anandamide (AEA) triggers apoptosis. Here, we aim to investigate the role of its receptors on ANE-induced apoptosis and its signaling pathway in human dental pulp cells (HPC). AEA clearly induced apoptosis on HPC. Both CB2 antagonist and VR1 antagonist inhibited AEA-induced cell death. An inhibitor of extracellular signal-regulated kinases (ERKs) significantly prevented HPC cell death. ERK inhibitors and CB2 antagonist inhibited AEA-regulated nuclear factor-kappa B (NF-κB) activation. Furthermore, specific siRNA for NF-κB suunits (p50 and p65) inhibited AEA-induced HPC cell death. In this regard, AEA-induced pulp apoptosis was regulated by NF-κB-dependent and-independent pathways.Substance P (SP) induces the expression of proinflammatory cytokines, such as interleukin (IL)-6, which are implicated in pulp inflammation. To determine the signal pathway of SP-induced IL-6, we examined the activities of the mitogen-activated protein kinases (MAPKs) in human dental pulp cell (PF-10) cultures. SP induced the phosphorylation of p38 MAPK within 5 min; this activation persisted for up to 40 min and was independent of the activation of extracellular signal-related kinases (ERK-1 and ERK-2), which was induced after SP stimulation of PF-10 cells. As shown by electrophoresic mobility shift assay (EMSA), p38 MAPK was not involved in SP-induced activation of nuclear factor-kappa B (NF-κB). However, p38 MAPK mediated SP-induced IL-6 production, as shown by the use of specific inhibitors of this kinase. Our results suggest that the activation of p38 MAPK is important for NF-κB-independent regulator of neurogenic inflammation in dental pulp tissues.