Kolachala Vasantha L, Bajaj Rahul, Wang Lixin, Yan Yutao, Ritzenthaler Jeff D, Gewirtz Andrew T, Roman Jesse, Merlin Didier, Sitaraman Shanthi V
Division of Digestive Diseases, Department of Medicine, Emory University, 615 Michael Street, Atlanta, GA 30322, USA.
J Biol Chem. 2007 Nov 9;282(45):32965-73. doi: 10.1074/jbc.M704388200. Epub 2007 Sep 13.
Fibronectin (FN) is a multifunctional extracellular matrix protein that plays an important role in cell proliferation, adhesion, and migration. FN expression or its role in colitis is not known. The goal of this study is to characterize FN expression, regulation, and role during intestinal inflammation. Wild-type and transgenic mice expressing luciferase under the control of the human FN promoter, given water or 3% dextran sodium sulfate, were used as animal models of colitis. The Caco2-BBE model intestinal epithelial cell line was used for in vitro studies. FN protein is abundantly expressed by surface epithelial cells in the normal colon. Immunohistochemistry and luciferase assay in mice expressing the FN promoter linked to luciferase demonstrated that FN synthesis was up-regulated during colitis, during both the acute phase and the healing phase. In vitro experiments demonstrated that FN increased the expression of the FN integrin receptor alpha5beta1 in a dose- and time-dependent manner. FN also induced the expression and activation of NF-kappaB. Further, FN potentiated Caco2-BBE cell attachment and wound healing, which was inhibited by RGD peptide as well as NF-kappaB inhibitors MG-132 and 1-pyrrolidinecarbodithioic acid, ammonium salt. In conclusion, FN is abundantly expressed and synthesized by colonic epithelial cells. FN is transcriptionally up-regulated in epithelial cells during both the dextran sodium sulfate-induced colitic and the recovery phase. FN enhances cell attachment and wound healing, which is dependent on binding to the integrin receptor and the NF-kappaB signaling. Together our data show that epithelial-derived FN potentiates cell attachment and wound healing through epithelial-matrix interactions and that FN expression may have important implications for maintaining normal epithelial integrity as well as regulating epithelial response to injury during colitis.
纤连蛋白（FN）是一种多功能细胞外基质蛋白，在细胞增殖、黏附和迁移中发挥重要作用。FN在结肠炎中的表达情况或其作用尚不清楚。本研究的目的是明确肠道炎症期间FN的表达、调控及其作用。将在人FN启动子控制下表达荧光素酶的野生型和转基因小鼠给予水或3%葡聚糖硫酸钠，用作结肠炎动物模型。使用Caco2-BBE模型肠道上皮细胞系进行体外研究。在正常结肠中，表面上皮细胞大量表达FN蛋白。对表达与荧光素酶相连的FN启动子的小鼠进行免疫组织化学和荧光素酶测定表明，在结肠炎的急性期和愈合期，FN合成均上调。体外实验表明，FN以剂量和时间依赖性方式增加FN整合素受体α5β1的表达。FN还诱导NF-κB的表达和激活。此外，FN增强Caco2-BBE细胞黏附和伤口愈合，RGD肽以及NF-κB抑制剂MG-132和1-吡咯烷二硫代羧酸铵盐可抑制这种作用。总之，结肠上皮细胞大量表达和合成FN。在葡聚糖硫酸钠诱导的结肠炎及恢复阶段，上皮细胞中FN转录上调。FN增强细胞黏附和伤口愈合，这依赖于与整合素受体的结合及NF-κB信号传导。我们的数据共同表明，上皮来源的FN通过上皮-基质相互作用增强细胞黏附和伤口愈合，并且FN表达可能对维持正常上皮完整性以及调节结肠炎期间上皮对损伤的反应具有重要意义。
