Department of Medicine, New York Medical College, Valhalla, NY 10595, USA.
Am J Physiol Renal Physiol. 2012 Mar 15;302(6):F730-41. doi: 10.1152/ajprenal.00520.2011. Epub 2011 Dec 21.
We aimed to investigate the potential relationship between alarmins [acting via Toll-like receptor-4 (TLR4)], uric acid (UA), and high-mobility group box-1 protein (HMGB1) during acute kidney injury. UA, which is significantly increased in the circulation following renal ischemia-reperfusion injury (IRI), was used both in vitro and in vivo as an early response-signaling molecule to determine its ability to induce the secretion of HMGB1 from endothelial cells. Treatment of human umbilical vein endothelial cells (HUVEC) with UA resulted in increased HMGB1 mRNA expression, acetylation of nuclear HMGB1, and its subsequent nuclear-cytoplasmic translocation and release into the circulation, as determined by Western blotting and immunofluorescence. Treatment of HUVEC with UA and a calcium mobilization inhibitor (TMB-8) or a MEK/Erk pathway inhibitor (U0126) prevented translocation of HMGB1 from the nucleus, resulting in reduced cytoplasmic and circulating levels of HMGB1. Once released, HMGB1 in autocrine fashion promoted further HMGB1 release while also stimulating NF-κB activity and increased angiopoietin-2 expression and protein release. Transfection of HUVEC with TLR4 small interfering (si) RNA reduced HMGB1 levels during UA and HMGB1 treatment. In summary, UA after IRI mediates the acetylation and release of HMGB1 from endothelial cells by mechanisms that involve calcium mobilization, the MEK/Erk pathway, and activation of TLR4. Once released, HMGB1 promotes its own further cellular release while acting as an autocrine and paracrine to activate both proinflammatory and proreparative mediators.
我们旨在研究在急性肾损伤中，警报素（通过 Toll 样受体-4（TLR4）发挥作用）、尿酸（UA）和高迁移率族蛋白 B1（HMGB1）之间的潜在关系。UA 在肾缺血再灌注损伤（IRI）后循环中显著增加，被用作体外和体内的早期反应信号分子，以确定其诱导内皮细胞分泌 HMGB1 的能力。UA 处理人脐静脉内皮细胞（HUVEC）导致 HMGB1 mRNA 表达增加，核 HMGB1 乙酰化，随后核质转位并释放到循环中，通过 Western blot 和免疫荧光检测。用 UA 和钙动员抑制剂（TMB-8）或 MEK/Erk 通路抑制剂（U0126）处理 HUVEC 可防止 HMGB1 从核内转位，导致细胞质和循环中 HMGB1 水平降低。一旦释放，HMGB1 以自分泌方式促进进一步的 HMGB1 释放，同时刺激 NF-κB 活性并增加血管生成素-2 的表达和蛋白释放。用 TLR4 小干扰（si）RNA 转染 HUVEC 可减少 UA 和 HMGB1 处理过程中的 HMGB1 水平。总之，IRI 后的 UA 通过涉及钙动员、MEK/Erk 通路和 TLR4 激活的机制介导内皮细胞中 HMGB1 的乙酰化和释放。一旦释放，HMGB1 促进自身进一步的细胞释放，同时作为自分泌和旁分泌激活促炎和修复性介质。
