Regulation mechanism of production and secretion of mucin in intestinal goblet cells

肠粘蛋白是一种主要在杯状细胞中产生的大分子糖蛋白，对保护上皮表面免受有害病原体的侵害具有重要作用。我们研究了一些细胞因子对人结肠癌细胞株LS174T和HT29中粘蛋白表达的调控机制的影响。IL-13刺激LS174T细胞分泌粘蛋白。RT-PCR结果显示，LS174T和HT29细胞表达IL-4、IL-13和TNF-α受体mRNA。IL-4、IL-13和TNF-α刺激LS174T细胞MUC2 mRNA的表达，MUC2是结肠中主要的粘蛋白核心蛋白。而IL-4和IL-13在HT29细胞中不刺激MUC2基因的表达。TNF-a刺激HT29细胞MUC2基因表达。在两种细胞系中，IL-4和IL-13激活了JAK/STAT信号转导通路中STAT6的磷酸化。IL-4和IL-13在LS174T细胞中激活MAPK磷酸化，而TNF-α不激活MAPK磷酸化，而IL-4、IL-13和TNF-α在HT29细胞中激活MAPK磷酸化。MAPK激酶特异性抑制剂U0126抑制IL-4和IL-13诱导的LS174T细胞MUC2基因表达和TNF-α诱导的HT29细胞MUC2基因表达。这些结果表明，在人结肠癌细胞系中，IL-4、IL-13或TNF-α通过MAPK途径刺激MUC2基因表达。

Intestinal mucin is a large molecular glycoprotein produced mainly in goblet cells, and important to protect the epithelial surface from harmful pathogens. We studied on effect of some cytokines on regulation mechanism of mucin expression in the human colon cancer cell lines, LS174T and HT29. IL-13 stimulated mucin secretion from LS174T cells. RT-PCR showed that LS174T and HT29 cells expressed mRNA of receptors of IL-4, IL-13 and TNF-α. IL-4, IL-13 and TNF-α stimulated the mRNA expression of MUC2, which is a major mucin core protein in the colon, in LS174T cells. IL-4 and IL-13, however, did not stimulate MUC2 gene expression in HT29 cells. TNF-a stimulated MUC2 gene expression in HT29 cells. IL-4 and IL-13 activated phosphorylation of STAT6 in the JAK/STAT signal transduction pathway in both cell lines. IL-4 and IL-13 but not TNF-α activated phosphorylation of MAPK in LS174T cells, whereas IL-4, IL-13 and TNF-α activated phosphorylation of MAPK in HT29 cells. A specific inhibitor of MAPK kinase, U0126, inhibited the MUC2 gene expression induced with IL-4 and IL-13 in LS174T cells and the expression induced with TNF-α in HT29. These results suggest that MUC2 gene expression is stimulated with IL-4, IL-13, or TNF-α through a MAPK pathway in the human colon cancer cell lines.