Extracellular High Mobility Group Box-1 (HMGB1) Inhibits Enterocyte Migration via Activation of Toll-like Receptor-4 and Increased Cell-Matrix Adhesiveness
Extracellular High Mobility Group Box-1 (HMGB1) Inhibits Enterocyte Migration via Activation of Toll-like Receptor-4 and Increased Cell-Matrix Adhesiveness
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DOI：
10.1074/jbc.m109.067454
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发表时间：
2010-02-12
影响因子：
4.8
通讯作者：
Hackam, David J.
中科院分区：
文献类型：
--
作者：
Dai, Shipan;Sodhi, Chhinder;Hackam, David J.
Toll样受体-4（TLR 4）是细菌脂多糖的受体，但它也可能对多种内源性分子产生应答。坏死性小肠结肠炎（NEC）是新生儿胃肠道疾病死亡的主要原因，其特征在于肠粘膜破坏和肠上皮细胞迁移受损，这是由于肠上皮细胞上的TLR 4信号传导增加。导致肠上皮细胞迁移受损的TLR 4的内源性配体仍然未知。高迁移率族蛋白1（HMGB 1）是一种DNA结合蛋白，在炎症过程中从受损细胞中释放。因此，我们假设细胞外HMGB 1通过激活TLR 4抑制肠上皮细胞迁移，并试图确定所涉及的途径。我们现在证明，小鼠和人类NEC与肠HMGB 1表达增加，血清HMGB 1在小鼠NEC中增加，HMGB 1在体外和体内以TLR 4依赖性方式抑制肠上皮细胞迁移。这一发现对于肠细胞是独特的，因为HMGB 1在体外和体内增强了炎性细胞的迁移。在寻求理解所涉及的机制时，TLR 4依赖性HMGB 1信号增加了肠上皮细胞中RhoA的活化，增加了粘着斑激酶的磷酸化，增加了cofilin的磷酸化，导致应力纤维和粘着斑增加。使用单细胞力牵引显微镜，HMGB 1信号传导的净效应是TLR 4依赖性的细胞力粘附增加，解释了受损的肠上皮细胞迁移。这些发现证明了HMGB 1激活TLR 4延迟粘膜修复的新途径，并提出了改善肠道炎症性疾病（如NEC）的新的潜在治疗靶点。
Toll-like receptor-4 (TLR4) is the receptor for bacterial lipopolysaccharide, yet it may also respond to a variety of endogenous molecules. Necrotizing enterocolitis (NEC) is the leading cause of death from gastrointestinal disease in newborn infants and is characterized by intestinal mucosal destruction and impaired enterocyte migration due to increased TLR4 signaling on enterocytes. The endogenous ligands for TLR4 that lead to impaired enterocyte migration remain unknown. High mobility group box-1 (HMGB1) is a DNA-binding protein that is released from injured cells during inflammation. We thus hypothesize that extracellular HMGB1 inhibits enterocyte migration via activation of TLR4 and sought to define the pathways involved. We now demonstrate that murine and human NEC are associated with increased intestinal HMGB1 expression, that serum HMGB1 is increased in murine NEC, and that HMGB1 inhibits enterocyte migration in vitro and in vivo in a TLR4-dependent manner. This finding was unique to enterocytes as HMGB1 enhanced migration of inflammatory cells in vitro and in vivo. In seeking to understand the mechanisms involved, TLR4-dependent HMGB1 signaling increased RhoA activation in enterocytes, increased phosphorylation of focal adhesion kinase, and increased phosphorylation of cofilin, resulting in increased stress fibers and focal adhesions. Using single cell force traction microscopy, the net effect of HMGB1 signaling was a TLR4-dependent increase in cell force adhesion, accounting for the impaired enterocyte migration. These findings demonstrate a novel pathway by which TLR4 activation by HMGB1 delays mucosal repair and suggest a novel potential therapeutic target in the amelioration of intestinal inflammatory diseases like NEC.