Division of Orofacial Functions and Orthodontics, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580, Japan.
Division of Infections and Molecular Biology, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580, Japan.
Int J Mol Sci. 2023 Oct 2;24(19):14842. doi: 10.3390/ijms241914842.
The differentiation and function of osteocytes are controlled by surrounding cells and mechanical stress; however, the detailed mechanisms are unknown. Recent findings suggest that IL-33 is highly expressed in periodontal tissues in orthodontic tooth movement. The present study aimed to elucidate the effect of IL-33 on the expression of regulatory factors for bone remodeling and their molecular mechanisms in the osteocyte-like cell line MLO-Y4. MLO-Y4 cells were treated with IL-33, and the activation of intracellular signaling molecules and transcriptional factors was determined using Western blot analysis and chromatin immunoprecipitation assay. IL-33 treatment enhanced the expression of IL-6 in MLO-Y4 cells, which was suppressed by the knockdown of the IL-33 receptor ST2L. Additionally, IL-33 treatment induced activation of NF-κB, JNK/AP-1, and p38 MAPK signaling pathways in MLO-Y4 cells. Moreover, pretreatment with specific inhibitors of NF-κB, p38 MAPK, and JNK/AP-1 attenuated the IL-33-induced expression of IL-6. Furthermore, chromatin immunoprecipitation indicated that IL-33 increased c-Jun recruitment to the IL-6 promoter. Overall, these results suggest that IL-33 induces IL-6 expression and regulates osteocyte function via activation of the NF-κB, JNK/AP-1, and p38 MAPK pathways through interaction with ST2L receptors on the plasma membrane.
成骨细胞的分化和功能受周围细胞和机械应力的控制；然而，其详细机制尚不清楚。最近的研究结果表明，IL-33 在正畸牙齿移动的牙周组织中高度表达。本研究旨在阐明 IL-33 对成骨细胞样细胞系 MLO-Y4 中骨重塑调节因子表达的影响及其分子机制。用 IL-33 处理 MLO-Y4 细胞，通过 Western blot 分析和染色质免疫沉淀试验测定细胞内信号分子和转录因子的激活。IL-33 处理增强了 MLO-Y4 细胞中 IL-6 的表达，而 IL-33 受体 ST2L 的敲低则抑制了这种表达。此外，IL-33 处理诱导 MLO-Y4 细胞中 NF-κB、JNK/AP-1 和 p38 MAPK 信号通路的激活。此外，NF-κB、p38 MAPK 和 JNK/AP-1 的特异性抑制剂预处理减弱了 IL-33 诱导的 IL-6 表达。此外，染色质免疫沉淀表明，IL-33 增加了 c-Jun 向 IL-6 启动子的募集。综上所述，这些结果表明，IL-33 通过与质膜上的 ST2L 受体相互作用，激活 NF-κB、JNK/AP-1 和 p38 MAPK 通路，诱导 IL-6 表达，并调节成骨细胞功能。
