Iwashita Jun, Sato Yukita, Sugaya Hiroko, Takahashi Nagatomo, Sasaki Hiroshi, Abe Tatsuya
Molecular Biology, Akita Prefectural University, Akita 010-0195, Japan.
Immunol Cell Biol. 2003 Aug;81(4):275-82. doi: 10.1046/j.1440-1711.2003.t01-1-01163.x.
MUC2 mucin is a secretory glycoprotein which is produced from the intestinal goblet cells and is a major component of the intestinal epithelial mucus. The biological function of MUC2 mucin is considered to be the protection of intestinal epithelial surface, whereas the regulatory mechanism of MUC2 mucin production in immune response is not completely understood. We have studied the effects of cytokines, IL-4, IL-13 and TNF-alpha, on the regulation of MUC2 mRNA in the human colonic cancer cell lines, LS174T and HT29. The quantitative reverse transcription-polymerase chain reaction showed that single addition of IL-4, IL-13 and TNF-alpha to cell culture induced about two-fold increase of MUC2 mRNA level in LS174T cells. Interleukin-4 and IL-13 activated phosphorylation of mitogen-activated protein kinase in LS174T cells. A specific inhibitor of mitogen-activated protein kinase pathway, U0126, totally inhibited the increase of MUC2 mRNA by IL-4 or IL-13 in those cells. Therefore, mitogen-activated protein activation of kinase is required for the increase of MUC2 mRNA by IL-4 or IL-13 in LS174T cells. In contrast to LS174T cells, only TNF-alpha increased MUC2 mRNA through a mitogen-activated protein kinase pathway in HT29 cells that express low levels of MUC2 mRNA. These findings sustain a novel phenomenon that MUC2 mRNA expression is differently controlled by IL-4, IL-13, or TNF-alpha in LS174T and HT29 cells, whereas the mitogen-activated protein kinase pathway plays a role in the MUC2 mRNA expression induced by those cytokines in both cell lines.
MUC2黏蛋白是一种分泌性糖蛋白，由肠道杯状细胞产生，是肠道上皮黏液的主要成分。MUC2黏蛋白的生物学功能被认为是保护肠道上皮表面，而其在免疫反应中产生的调节机制尚未完全明确。我们研究了细胞因子白细胞介素-4（IL-4）、白细胞介素-13（IL-13）和肿瘤坏死因子-α（TNF-α）对人结肠癌细胞系LS174T和HT29中MUC2 mRNA调控的影响。定量逆转录-聚合酶链反应显示，在细胞培养中单独添加IL-4、IL-13和TNF-α可使LS174T细胞中的MUC2 mRNA水平增加约两倍。白细胞介素-4和IL-13激活了LS174T细胞中丝裂原活化蛋白激酶的磷酸化。丝裂原活化蛋白激酶途径的特异性抑制剂U0126完全抑制了这些细胞中IL-4或IL-13引起的MUC2 mRNA增加。因此，在LS174T细胞中，IL-4或IL-13引起的MUC2 mRNA增加需要丝裂原活化蛋白激酶的激活。与LS174T细胞不同，在表达低水平MUC2 mRNA的HT29细胞中，只有TNF-α通过丝裂原活化蛋白激酶途径增加MUC2 mRNA。这些发现支持了一种新现象，即LS174T和HT29细胞中MUC2 mRNA的表达受IL-4、IL-13或TNF-α的不同控制，而丝裂原活化蛋白激酶途径在这两种细胞系中由这些细胞因子诱导的MUC2 mRNA表达中发挥作用。
