Key Points The cell surface receptors RAGE and TLR4 regulate HMGB1-induced inflammation. RAGE promotes TLR4 trafficking to the cell surface but does not affect its translation. TLR4 regulates the translation of RAGE, which translocates to the cell surface. Receptor for advanced glycation end-products (RAGE) and TLR4 play an important role in the inflammatory response against High-mobility group box 1 protein (HMGB1), a late proinflammatory cytokine and a damage-associated molecular pattern. As cell surface receptors, both RAGE and TLR4 are constantly trafficking between the cytoplasm and plasma membrane. However, whether TLR4 is related to the intracellular transport of RAGE in HMGB1-induced inflammation remains unknown. In this study, we demonstrated that HMGB1 not only increased RAGE expression in both the cytoplasm and plasma membrane but also upregulated the expression of TLR4 in the plasma membrane. Knocking out of RAGE led to decreased MAPK activation, TLR4 cellular membrane expression, and corresponding inflammatory cytokine generation. Meanwhile, inhibiting MAPK activation also decreased TLR4 surface expression. These results indicated that HMGB1 may bind to cell surface RAGE receptors on the cell surface, leading to MAPK activation, thus promoting TLR4 translocation on the cell surface, but does not regulate its transcription and translation. In contrast, TLR4 can increase the transcription and translation of RAGE, which translocates to the cell surface and is able to bind to more HMGB1. The cell surface receptors TLR4 and RAGE bind to HMGB1, leading to the transcription and secretion of inflammatory cytokines. Finally, we also observed these results in the mice pseudofracture model, which is closely related to HMGB1-induced inflammatory response. All these results demonstrated that the interplay between RAGE and TLR4 are critical for HMGB1-induced inflammatory response.

中文翻译：

---

RAGE 和 TLR4 之间的相互作用通过促进 RAGE 和 TLR4 的细胞表面表达来调节 HMGB1 诱导的炎症

关键点 细胞表面受体 RAGE 和 TLR4 调节 HMGB1 诱导的炎症。RAGE 促进 TLR4 运输到细胞表面，但不影响其翻译。TLR4 调节 RAGE 的翻译，RAGE 易位到细胞表面。晚期糖基化终产物 (RAGE) 和 TLR4 的受体在针对高迁移率族框 1 蛋白 (HMGB1)、晚期促炎细胞因子和损伤相关分子模式的炎症反应中发挥重要作用。作为细胞表面受体，RAGE 和 TLR4 都在细胞质和质膜之间不断地运输。然而，TLR4 是否与 HMGB1 诱导的炎症中 RAGE 的细胞内转运有关仍然未知。在这项研究中，我们证明 HMGB1 不仅增加了细胞质和质膜中 RAGE 的表达，而且还上调了质膜中 TLR4 的表达。敲除 RAGE 导致 MAPK 活化减少、TLR4 细胞膜表达和相应的炎性细胞因子生成。同时，抑制 MAPK 激活也降低了 TLR4 表面表达。这些结果表明HMGB1可能与细胞表面的细胞表面RAGE受体结合，导致MAPK活化，从而促进细胞表面的TLR4易位，但不调节其转录和翻译。相比之下，TLR4 可以增加 RAGE 的转录和翻译，后者易位到细胞表面并能够与更多的 HMGB1 结合。细胞表面受体 TLR4 和 RAGE 与 HMGB1 结合，导致炎症细胞因子的转录和分泌。最后，我们还在小鼠假骨折模型中观察到这些结果，这与 HMGB1 诱导的炎症反应密切相关。所有这些结果表明，RAGE 和 TLR4 之间的相互作用对于 HMGB1 诱导的炎症反应至关重要。