文章基本信息

标题：Isoleucine, an Essential Amino Acid, Induces the Expression of Human β Defensin 2 through the Activation of the G-Protein Coupled Receptor-ERK Pathway in the Intestinal Epithelia
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作者：Youkou Konno ; Toshifumi Ashida ; Yuhei Inaba 等
期刊名称：Food and Nutrition Sciences
印刷版ISSN：2157-944X
电子版ISSN：2157-9458
出版年度：2012
卷号：3
期号：4
页码：548-555
DOI：10.4236/fns.2012.34077
出版社：Scientific Research Publishing
摘要：Anti-microbial peptides are essential for the intestinal innate immunity that protects the intestinal epithelia from attacks by foreign pathogens. Human β-defensin (HBD) is one of the pivotal anti-microbial peptides that are expressed in the colonic epithelia. This study investigated the effect and the signaling mechanism of inducible β-defensin HBD2 by an essential amino acid, isoleucine (Ile) in colonic epithelial cells. Here we examined the expression level of HBD2 on induction of Ile in epithelial cells, and checked this pathway. HBD2 mRNA was induced by co-incubation with IL-1α and Ile in Caco2 cells, but not by Ile alone. An inhibitor of either ERK or Gi, a subunit of G-proteins, reduced the induction of HBD2 mRNA by Ile. The treatment with Ile also increased the intracellular calcium ion concentration, thus suggesting that the GPCR and ERK signaling pathway mediate the effects of Ile. These results indicate that an essential amino acid, Ile, enhances the expression of an inducible β-defensin, namely HBD2, by IL-1α through the activation of GPCRs and ERK signaling pathway. The administration of Ile may therefore represent a possible option to safely treat intestinal inflammation.
关键词：Isoleucine; Human β-Defensin; G-Protein Coupled Receptor; Extracellular Signal-Regulated Kinases Pathway; Inflammatory Bowel Disease; Crohn’s Disease