Department of Endodontics, School and Hospital of Stomatology, Cheeloo College of Medicine, Shandong University and Shandong Key Laboratory of Oral Tissue Regeneration and Shandong Engineering Laboratory for Dental Materials and Oral Tissue Regeneration, Jinan, Shandong 250012, P.R. China.
Department of Endodontics, Yantai Stomatological Hospital, Yantai, Shandong 264008, P.R. China.
Mol Med Rep. 2020 Aug;22(2):1017-1025. doi: 10.3892/mmr.2020.11152. Epub 2020 May 18.
Elucidation of the underlying mechanisms governing osteogenic differentiation is of significant importance to the improvement of therapeutics for bone‑related inflammatory diseases. Tumor necrosis factor‑α (TNF‑α) is regarded as one of the major agents during osteogenic differentiation in an inflammatory environment. miR‑335‑5p post‑transcriptionally downregulates the Dickkopf WNT signaling pathway inhibitor 1 (DKK1) protein level by specifically binding to the DKK1 3'UTR and activating Wnt signaling. The role of miR‑335‑5p in TNF‑α‑induced post‑transcriptional regulation of DKK1 remains to be elucidated. In the present study, the mRNA and protein levels of DKK1 and the level of miR‑335‑5p were determined in MC3T3‑E1 cells and the primary calvarial osteoblasts treated with or without TNF‑α. The role of NF‑κB signaling in TNF‑α‑induced post‑transcriptional regulation of DKK1 was also evaluated. The present study determined that although TNF‑α treatment exhibited cell‑specific effects on DKK1 mRNA expression, the stimulation of TNF‑α time‑ and concentration‑dependently upregulated the protein levels of DKK1. In primary calvarial osteoblasts, the decreased miR‑335‑5p level induced by TNF‑α‑activated NF‑κB signaling served an important role in mediating the post‑transcriptional regulation of DKK1 by TNF‑α treatment. In MC3T3‑E1 cells, the post‑transcriptional regulation of DKK1 by TNF‑α treatment was more complicated and involved other molecular signaling pathways in addition to the NF‑κB signaling. In conclusion, TNF‑α treatment served an important role in the post‑transcriptional regulation of DKK1 expression, which requires further investigation. The results of the present study not only provided new insights into the regulatory effects of miR‑335‑5p on osteogenic differentiation in an inflammatory microenvironment, but may also promote the development of potential therapeutic strategies for the treatment of bone‑related inflammatory diseases.
阐明调控成骨分化的潜在机制对于改善与骨相关的炎症性疾病的治疗方法具有重要意义。肿瘤坏死因子-α（TNF-α）被认为是炎症环境中成骨分化过程中的主要因子之一。miR-335-5p 通过特异性结合 DKK1 的 3'UTR 并激活 Wnt 信号转导，从而转录后下调 Dickkopf WNT 信号通路抑制剂 1（DKK1）蛋白水平。miR-335-5p 在 TNF-α诱导的 DKK1 转录后调控中的作用仍有待阐明。在本研究中，测定了 TNF-α处理的 MC3T3-E1 细胞和原代颅骨成骨细胞中 DKK1 的 mRNA 和蛋白水平以及 miR-335-5p 的水平。还评估了 NF-κB 信号转导在 TNF-α诱导的 DKK1 转录后调控中的作用。本研究发现，尽管 TNF-α处理对 DKK1 mRNA 表达具有细胞特异性作用，但 TNF-α 的刺激时间和浓度依赖性地上调了 DKK1 蛋白水平。在原代颅骨成骨细胞中，TNF-α-激活的 NF-κB 信号转导下调的 miR-335-5p 水平在介导 TNF-α 处理对 DKK1 的转录后调控中发挥重要作用。在 MC3T3-E1 细胞中，TNF-α 处理对 DKK1 的转录后调控更为复杂，除了 NF-κB 信号转导外，还涉及其他分子信号通路。总之，TNF-α 处理在 DKK1 表达的转录后调控中起重要作用，需要进一步研究。本研究的结果不仅为 miR-335-5p 在炎症微环境中成骨分化的调控作用提供了新的见解，而且可能促进针对与骨相关的炎症性疾病的潜在治疗策略的发展。
