Special Key Laboratory of Gene Detection & Therapy of Guizhou Province, Zunyi, China.
Department of Immunology, Zunyi Medical University, Zunyi, China.
Immunology. 2021 Jan;162(1):44-57. doi: 10.1111/imm.13252. Epub 2020 Oct 19.
Toll-like receptor (TLR) 4 signalling is critical for innate immunoinflammatory response and widely triggers the development of various types of clinical diseases. MicroRNA-7 (miR-7) is well documented to play an important regulatory role in various biological events. However, the exact role of miR-7 in TLR4 signalling pathway remains to be fully elucidated. In the present study, we found that miR-7 expression in TLR4 signalling-activated bone marrow-derived macrophages (BMDMs) stimulated by LPS was dramatically increased. Importantly, miR-7 deficiency significantly enhanced the production of related inflammatory cytokines including IL-1β, IL-6 and IL-12, as well as TNF-α, on LPS-activated BMDMs, accompanied by elevated transduction of TLR4 signalling including Myd88-dependent and Myd88-independent pathways, whereas miR-7 overexpression significantly decreased the transduction of TLR4 signalling and the production of related inflammatory cytokines. Mechanistically, we identified family with sequence similarity 177, member A (FAM177A) as a novel target molecule of miR-7. Furthermore, down-regulation of FAM177A using RNAi could impair the transduction of TLR4 signalling. Finally, down-regulation of FAM177A also reversed the effect of miR-7 deficiency on TLR4 signalling transduction and production of related inflammatory cytokines on BMDMs. Therefore, we provide the new evidence that miR-7 acts as a novel negative fine-tuner in regulating TLR4 signalling pathways by targeting FAM177A, which might throw light on the basal understanding on the regulatory mechanism of TLR4 signalling and benefit the development of therapeutic strategies against related clinical diseases.
Toll 样受体 (TLR) 4 信号通路对于先天免疫炎症反应至关重要，并广泛触发各种类型的临床疾病的发展。MicroRNA-7 (miR-7) 在各种生物事件中发挥着重要的调节作用，这一点已有充分的文献记载。然而，miR-7 在 TLR4 信号通路中的确切作用仍有待充分阐明。在本研究中，我们发现 LPS 刺激的 TLR4 信号激活的骨髓来源巨噬细胞 (BMDM) 中 miR-7 的表达显著增加。重要的是，miR-7 缺失显著增强了 LPS 激活的 BMDM 中相关炎症细胞因子的产生，包括 IL-1β、IL-6 和 IL-12 以及 TNF-α，同时也增强了 TLR4 信号的转导，包括 Myd88 依赖性和 Myd88 非依赖性途径，而 miR-7 过表达则显著降低了 TLR4 信号的转导和相关炎症细胞因子的产生。在机制上，我们鉴定出 FAM177A 是 miR-7 的一个新的靶分子。此外，使用 RNAi 下调 FAM177A 会损害 TLR4 信号的转导。最后，下调 FAM177A 也逆转了 miR-7 缺失对 BMDM 中 TLR4 信号转导和相关炎症细胞因子产生的影响。因此，我们提供了新的证据表明，miR-7 通过靶向 FAM177A 作为调节 TLR4 信号通路的新型负调控因子，这可能为 TLR4 信号通路的调节机制提供新的认识，并有助于开发针对相关临床疾病的治疗策略。
