MUC2基因沉默对脂多糖干扰Caco-2/HT-29细胞紧密连接蛋白表达的影响

Effect of MUC2 Gene Silencing on Tight Junction Protein Expression in Caco-2/HT-29 Co-culture Cells by Lipopolysaccharides Interference

肠道黏膜屏障阻碍病原物质入侵的第一道防线是由黏蛋白-2(MUC2)组成的肠道黏液层,覆盖于上皮细胞表面,由杯状细胞分泌而成。脂多糖(lipopolysaccharides, LPS)可通过损伤肠黏膜从而干扰屏障功能的正常发挥。论文对Caco-2/HT-29(3∶1)共培养模拟肠道上皮细胞,通过沉默黏蛋白-2(siMUC2)分析脂多糖对肠道黏液层屏障及其上皮紧密连接结构的影响。结果显示,与对照组相比,LPS组E-钙黏素(E-cadherin)、闭合蛋白mRNA表达量均明显降低。与LPS组相比,LPS+siMUC2组中连接蛋白(claudin)、连接附着分子(JAMA)、E-cadherin以及桥粒(desmosome) mRNA水平显著降低,细胞连接蛋白mRNA水平的下调可能影响细胞通透性进而导致屏障功能紊乱。说明黏蛋白-2作为黏液层骨架蛋白成分可以保护细胞紧密连接蛋白免受LPS的干扰。LPS可诱导Caco-2/HT-29细胞模型黏蛋白-2表达增多以及E-cadherin、闭合蛋白mRNA表达下调。当黏蛋白-2基因被沉默后,LPS可导致细胞紧密连接蛋白mRNA表达量的显著下降,提示肠道上皮细胞紧密连接的屏障功能可能被破坏。

The first line of defense against the invasion of pathogenic substances by the intestinal mucosal barrier is the intestinal mucus layer composed of mucin-2(MUC2),which covers the surface of epithelial cells and is secreted by goblet cells.Lipopolysaccharides(LPS)can interfere with the normal functioning of the intestinal barrier by damaging the intestinal mucosa.Based on this,this study used Caco-2/HT-29(3:1)co culture to simulate intestinal epithelial cells,and analyzed the effect of LPS on the intestinal mucosal barrier and its tight junction structure by silencing MUC2(siMUC2).The results showed that compared with the control group,the expression levels of E-cadherin and occlusins mRNA in the LPS group were significantly reduced.Compared with the LPS group,the levels of claudin,JAMA,E-cadherin,and desmosome mRNA in the LPS+siMUC2 group were significantly reduced.Downregulation of cell junction protein mRNA levels may affect cell permeability and lead to barrier dysfunction.In summary,MUC2,as a component of the mucus layer skeleton protein,can protect cell tight junction proteins from LPS interference.LPS can induce an increase in MUC2 expression and a downregulation of E-cadherin and occludins mRNA expression in Caco-2/HT-29 cell models.When the MUC2 gene is silenced,LPS can lead to a significant decrease in the expression of tight junction protein mRNA,indicating that the barrier function of tight junctions in intestinal epithelial cells may be disrupted.