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

肠粘蛋白是一种主要由杯状细胞产生的大分子糖蛋白，对保护肠上皮细胞表面免受有害病原体的侵害具有重要作用。本实验研究了几种细胞因子对人结肠癌细胞株LS 174 T和HT 29中粘蛋白表达的调控机制。IL-13刺激LS 174 T细胞分泌粘蛋白。RT-PCR结果显示，LS 174 T和HT 29细胞表达IL-4、IL-13和TNF-α受体mRNA。IL-4、IL-13和TNF-α刺激LS 174 T细胞中MUC 2的mRNA表达，MUC 2是结肠中的主要粘蛋白核心蛋白。然而，IL-4和IL-13并不刺激HT 29细胞中MUC 2基因的表达。TNF-α刺激HT 29细胞中MUC 2基因的表达。IL-4和IL-13在两种细胞系中激活JAK/STAT信号转导通路中的STAT 6磷酸化。IL-4、IL-13和TNF-α可激活LS 174 T细胞MAPK磷酸化，而对HT-29细胞MAPK磷酸化无影响。MAPK激酶特异性抑制剂U 0126可抑制IL-4和IL-13诱导的LS 174 T细胞MUC 2基因表达及TNF-α诱导的HT 29细胞MUC 2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MUC 2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.