Activating Transcription Factor-2 Activation Epithelial Barrier Involves p38 Kinase and Modulation of Intestinal b Mechanism of IL-1
Activating Transcription Factor-2 Activation Epithelial Barrier Involves p38 Kinase and Modulation of Intestinal b Mechanism of IL-1
复制标题
DOI：
--
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Rana Al-Sadi;Shuhong Guo;D. Ye;K. Dokladny;T. Alhmoud;Lisa Ereifej;H. Said;T. Ma
中科院分区：
文献类型：
--
作者：
Rana Al-Sadi;Shuhong Guo;D. Ye;K. Dokladny;T. Alhmoud;Lisa Ereifej;H. Said;T. Ma
肠上皮细胞紧密连接（TJ）屏障的缺陷被认为是导致肠道炎症的重要致病因素。研究表明，促炎性细胞因子IL-1 B可引起肠道通透性增加，但其信号通路和分子机制尚不清楚。本研究的主要目的是研究p38激酶通路的作用和所涉及的分子过程。在这些研究中，体外肠上皮模型系统（Caco-2单层）用于描述细胞和分子机制，补充的体内小鼠模型系统（肠灌注）用于评估体外结果的体内相关性。我们的数据表明，IL-1 B增加Caco-2 TJ渗透性与p38激酶的激活相关。p38激酶的激活引起p38激酶底物激活转录因子（ATF）-2的磷酸化和激活。激活的ATF 2易位到细胞核，在那里它附着到肌球蛋白L链激酶（MLCK）启动子区域上的结合基序，导致MLCK启动子活性和基因转录的激活。小干扰RNA（siRNA）可诱导ATF-2基因沉默或ATF-2结合基序突变，从而抑制MLCK启动子的激活和MLCK mRNA的转录。此外，体内肠灌注研究还表明，IL-1 B增加小鼠肠通透性需要p38激酶依赖性激活ATF-2。总之，这些研究表明，IL-1 B诱导的体外和体内肠TJ通透性增加受ATF-2的p38激酶活化和MLCK基因活性的ATF-2调节的调节。
The defective intestinal epithelial tight junction (TJ) barrier has been postulated to be an important pathogenic factor contributing to intestinal inflammation. It has been shown that the proinflammatory cytokine IL-1 b causes an increase in intestinal permeability; however, the signaling pathways and the molecular mechanisms involved remain unclear. The major purpose of this study was to investigate the role of the p38 kinase pathway and the molecular processes involved. In these studies, the in vitro intestinal epithelial model system (Caco-2 monolayers) was used to delineate the cellular and molecular mechanisms, and a complementary in vivo mouse model system (intestinal perfusion) was used to assess the in vivo relevance of the in vitro findings. Our data indicated that the IL-1 b increase in Caco-2 TJ permeability correlated with an activation of p38 kinase. The activation of p38 kinase caused phosphorylation and activation of p38 kinase substrate, activating transcription factor (ATF)-2. The activated ATF2 translocated to the nucleus where it attached to its binding motif on the myosin L chain kinase (MLCK) promoter region, leading to the activation of MLCK promoter activity and gene transcription. Small interfering RNA induced silencing of ATF-2, or mutation of the ATF-2 binding motif prevented the activation of MLCK promoter and MLCK mRNA transcription. Addi-tionally, in vivo intestinal perfusion studies also indicated that the IL-1 b increase in mouse intestinal permeability required p38 kinase–dependent activation of ATF-2. In conclusion, these studies show that the IL-1 b –induced increase in intestinal TJ permeability in vitro and in vivo was regulated by p38 kinase activation of ATF-2 and by ATF-2 regulation of MLCK gene activity.