HOME
Return to Table of Contents
47 POTENTIAL RECRUITMENT OF THE NOD-1 PROTEIN DURING HELICOBACTER PYLORI INFECTION E Galindo-Mata, S Coles, NL Jones INTRODUCTION: Helicobacter pylori (H pylori) causes a chronic infection in over 50% of the world's population and is directly linked to the development of peptic ulcers and gastric cancers. Recent evidence indicates that innate immune responses have important implications in chronic diseases. While toll-like receptors are understood to be part of a cell's extracellular recognition system in the detection of pathogens, little is know about intracellular recognition systems. Nod proteins are newly described intracellular pattern recognition molecules that respond to a specific component of peptidoglycan from bacterial cell walls. Nod-1 is implicated in directing innate immune responses against bacteria in macrophages and epithelial cells. Nod-1 activates NF-kB, which leads to the induction of proinflammatory pathways. Recent evidence indicates that the gastric pathogen H pylori, activates Nod-1. It remains unknown, however, whether Nod-1 directly or indirectly recognizes the bacteria.
Research Institute, The Hospital for Sick Children, Department of Paediatrics and Physiology, University of Toronto, Toronto, Ontario
AIMS: Therefore the aims of this study were to determine the subcellular localization of Nod-1 and to delineate its role in cell responses to H pylori infection.
METHODS: Three cell lines were used: AGS (gastric carcinoma), HeLa (cervical cancer) and Hep-2 (laryngeal carcinoma) cells. The cells were cultured and transfected with gfp-tagged Nod-1 protein (wild-type or mutant), and with a plasma membrane-targeted protein (PM-red). Nontransfected cells were used as controls. A portion of the cells was infected with H pylori (moi=100), for various times (2 h, 6 h and 24 h). The cells were fixed and immunolabelled using anti-H pylori and anti-calnexin (endoplasmic reticulum marker) antibodies. Cells were visualized using confocal microscopy to determine colocalization.
RESULTS AND CONCLUSIONS: In transfected/uninfected HeLa cells wild type Nod-1 protein was primarily localized to the plasma membrane as assessed by colocalization with PM-red. In marked contrast, mutant Nod-1 appeared diffusely throughout the cell. Ongoing experiments will determine if Nod-1 is recruited during H pylori infection, helping to elucidate mechanisms by which Nod-1 functions as an intracellular pathogen recognition system.