Interleukin-8 is a chemokine which is chemotactic for neutrophils and T-lymphocytes and plays a crucial role in the pathogenesis of inflammatory bowel disease. Intestinal mucosal epithelial cells produce IL-8 in response to pathogens which mediates bidirectional communication between pathogen and host. The objective of this study was to investigate the molecular mechanisms involved in IL-8 gene regulation in T84 human colonic epithelial cells. To determine if IL-8 plays a role in the pathogenesis of intestinal amebiasis, the effect of Entamoeba histolytica on IL-8 gene expression was investigated. E. histolytica secreted components enhanced IL-8 mRNA expression and protein production in the absence of amebae-enterocyte contact. The proinflammatory cytokines IL-1beta and TNF-alpha were not involved in IL-8 protein production. As PGE2 is central in mucosal inflammation, the effect of PGE2 on IL-8 gene expression was determined. Using purified PGE2 and PGE2 receptor agonists, it was shown that PGE2 coupled to the EP4 receptor and triggered cAMP-dependent PKA signaling which upregulated IL-8 mRNA expression at the posttranscriptional level. Elevation of [Ca 2+]i from intracellular Ca2+ stores by A23187 or thapsigargin stimulated IL-8 mRNA transcription and IL-8 protein production through the activation of calcineurin. Moreover, IL-8 3'-UTR had a strong suppressive effect on CAT reporter gene expression in COS7 cells by reducing its mRNA level. A unique fragment (nt 2387-2743) containing AU rich elements was shown to attenuate CAT mRNA expression by destabilizing the transcripts. Secondary structure but not AU rich elements played a major role in CAT mRNA turnover.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.37579 |
| Date | January 1999 |
| Creators | Yu, Yi, 1965- |
| Contributors | Chadee, Kris (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Institute of Parasitology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001738024, proquestno: NQ55396, Theses scanned by UMI/ProQuest. |
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