Graduate School of Medical Science, Kumamoto Health Science University, Kitaku Izumi-machi 325, Kumamoto 861-5598, Japan.
Department of Neuroscience, Graduate School of Medicine, Kyoto University, Yoshida-konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
Cytokine. 2018 Aug;108:24-36. doi: 10.1016/j.cyto.2018.03.011. Epub 2018 Mar 17.
The stimuli inducing expression of single immunoglobulin IL-1-related receptor (SIGIRR) and the relevant regulatory mechanisms are not well defined. Transforming growth factor β1 (TGFβ1) delays internalization of neurokinin-1 receptor (NK1R) and subsequently enhances cellular signaling. This study investigated the effect of TGFβ1 on SIGIRR protein production by human M1 macrophages in response to stimulation with substance P (SP). SP caused upregulation of SIGIRR expression in a concentration-dependent manner, whereas aprepitant (an NK1R inhibitor) blunted this response. Silencing p38γMAPK or TAK-1 partially attenuated the response to SP stimulation, while TGFβ1/2/3 siRNA dramatically diminished it. SP induced much greater SIGIRR protein production than either lipopolysaccharide (a TLR4 agonist) or resiquimod (a TLR7/8 agonist). Unexpectedly, silencing of transcription factor specificity protein 1 (Sp1) led to significant upregulation of SIGIRR expression after SP stimulation, while KLF2 siRNA only partially enhanced it and Fli-1 siRNA reduced it. SP also upregulated TGFβ1 expression, along with a corresponding increase of SIGIRR protein, whereas silencing TGFβ1/2/3 blunted these responses. Sp1 siRNA or mithramycin (a gene-selective Sp1 inhibitor) significantly enhanced the expression of TGFβ1 and SIGIRR by macrophages after SP stimulation. Importantly, this effect of Sp1 siRNA on TGFβ1 and SIGIRR was blunted by siRNA for Smad2, Smad3, or Smad4, but not by TAK-1 siRNA. Next, we investigated the influence of transcription factor cross-talk on SIGIRR expression in response to SP. Co-transfection of macrophages with Sp1 siRNA and C/EBPβ or TIF1β siRNA attenuated the upregulation of SIGIRR by SP, while a combination of Sp1 siRNA and Fli-1 siRNA dramatically diminished it. In conclusion, TGFβ1 may be an intermediary between SP/NK1R activation and SIGIRR expression in Sp1 siRNA-transfected macrophages. In addition, Sp1 modulates TGFβ1/Smad signaling and negatively regulates SIGIRR protein production by macrophages after SP stimulation.
诱导单免疫球蛋白白细胞介素 1 相关受体 (SIGIRR) 表达的刺激物及其相关调节机制尚未完全明确。转化生长因子β1（TGFβ1）可延迟神经激肽-1 受体（NK1R）的内化，从而增强细胞信号转导。本研究探讨了 TGFβ1 对人 M1 巨噬细胞在受到 P 物质（SP）刺激时产生 SIGIRR 蛋白的影响。SP 呈浓度依赖性地上调 SIGIRR 表达，而 aprepitant（一种 NK1R 抑制剂）则减弱了这种反应。沉默 p38γMAPK 或 TAK-1 可部分减弱对 SP 刺激的反应，而 TGFβ1/2/3 siRNA 则显著减弱。SP 诱导的 SIGIRR 蛋白产生量远高于脂多糖（TLR4 激动剂）或 resiquimod（TLR7/8 激动剂）。出乎意料的是，沉默转录因子特异性蛋白 1（Sp1）后，SP 刺激导致 SIGIRR 表达显著上调，而 KLF2 siRNA 仅部分增强，Fli-1 siRNA 则降低。SP 还上调 TGFβ1 表达，同时相应增加 SIGIRR 蛋白，而沉默 TGFβ1/2/3 则阻断这些反应。Sp1 siRNA 或米托蒽醌（一种基因选择性 Sp1 抑制剂）可显著增强 SP 刺激后巨噬细胞中 TGFβ1 和 SIGIRR 的表达。重要的是，Sp1 siRNA 对 TGFβ1 和 SIGIRR 的这种影响可被 Smad2、Smad3 或 Smad4 的 siRNA 阻断，但不能被 TAK-1 siRNA 阻断。接下来，我们研究了转录因子相互作用对 SP 刺激后 SIGIRR 表达的影响。用 Sp1 siRNA 和 C/EBPβ 或 TIF1β siRNA 共转染巨噬细胞可减弱 SP 对 SIGIRR 的上调作用，而 Sp1 siRNA 和 Fli-1 siRNA 的组合则显著降低。总之，TGFβ1 可能是 SP/NK1R 激活和 Sp1 siRNA 转染巨噬细胞中 SIGIRR 表达之间的中介。此外，Sp1 调节 TGFβ1/Smad 信号转导，并负调控 SP 刺激后巨噬细胞中 SIGIRR 蛋白的产生。
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