Endotoxin inhibits intestinal epithelial restitution through activation of Rho-GTPase and increased focal adhesions
Endotoxin inhibits intestinal epithelial restitution through activation of Rho-GTPase and increased focal adhesions
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DOI：
10.1074/jbc.m313620200
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发表时间：
2004-06-04
影响因子：
4.8
通讯作者：
Hackam, DJ
中科院分区：
文献类型：
--
作者：
Cetin, S;Ford, HR;Hackam, DJ
肠道炎症疾病，如新生儿坏死性小肠结肠炎（NEC），是肠道粘膜损伤后导致细菌和内毒素（脂多糖）移位的结果。肠粘膜缺损通过肠恢复过程修复，在此过程中，肠细胞从健康区域迁移到损伤部位。在NEC的动物模型中，我们确定与对照动物相比，肠道恢复明显受损。因此，我们试图确定基础条件下和内毒素攻击后肠上皮细胞迁移的机制。在这里，我们表明，IEC-6肠上皮细胞迁移所需的细胞骨架重组和应力纤维的形成需要RhoA。发现肠细胞表达内毒素受体Toll样受体4，其用于结合和内化脂多糖。引人注目的是，内毒素治疗显着抑制肠的恢复，通过受损的IEC-6细胞迁移通过刮伤测量。发现脂多糖以磷脂酰肌醇3-激酶依赖性方式增加RhoA活性，导致粘着斑激酶磷酸化增加和粘着斑数量增加。重要的是，内毒素引起细胞基质张力/收缩力的进行性RhoA依赖性增加，这与观察到的肠上皮细胞迁移受损相关。因此，我们得出结论，内毒素抑制肠上皮细胞迁移通过RhoA依赖性增加局灶性粘连和增强细胞粘附，这可能参与受损的恢复观察到实验NEC。
Diseases of gut inflammation such as neonatal necrotizing enterocolitis (NEC) result after an injury to the mucosal lining of the intestine, leading to translocation of bacteria and endotoxin ( lipopolysaccharide). Intestinal mucosal defects are repaired by the process of intestinal restitution, during which enterocytes migrate from healthy areas to sites of injury. In an animal model of NEC, we determined that intestinal restitution was significantly impaired compared with control animals. We therefore sought to determine the mechanisms governing enterocyte migration under basal conditions and after an endotoxin challenge. Here we show that the cytoskeletal reorganization and stress fiber formation required for migration in IEC-6 enterocytes requires RhoA. Enterocytes were found to express the endotoxin receptor Toll-like receptor 4, which served to bind and internalize lipopolysaccharide. Strikingly, endotoxin treatment significantly inhibited intestinal restitution, as measured by impaired IEC-6 cell migration across a scraped wound. Lipopolysaccharide was found to increase RhoA activity in a phosphatidylinositol 3-kinase-dependent manner, leading to an increase in phosphorylation of focal adhesion kinase and an enhanced number of focal adhesions. Importantly, endotoxin caused a progressive, RhoA-dependent increase in cell matrix tension/contractility, which correlated with the observed impairment in enterocyte migration. We therefore conclude that endotoxin inhibits enterocyte migration through a RhoA-dependent increase in focal adhesions and enhanced cell adhesiveness, which may participate in the impaired restitution observed in experimental NEC.