title: Entamoeba histolytica induces cell death of HT29 colonic epithelial cells via NOX1-derived ROS.
abstract: Entamoeba histolytica, which causes amoebic colitis and occasionally liver abscess in humans, is able to induce host cell death. However, signaling mechanisms of colon cell death induced by E. histolytica are not fully elucidated. In this study, we investigated the signaling role of NOX in cell death of HT29 colonic epithelial cells induced by E. histolytica. Incubation of HT29 cells with amoebic trophozoites resulted in DNA fragmentation that is a hallmark of apoptotic cell death. In addition, E. histolytica generate intracellular reactive oxygen species (ROS) in a contact-dependent manner. Inhibition of intracellular ROS level with treatment with DPI, an inhibitor of NADPH oxidases (NOXs), decreased Entamoeba-induced ROS generation and cell death in HT29 cells. However, pan-caspase inhibitor did not affect E. histolytica-induced HT29 cell death. In HT29 cells, catalytic subunit NOX1 and regulatory subunit Rac1 for NOX1 activation were highly expressed. We next investigated whether NADPH oxidase 1 (NOX1)-derived ROS is closely associated with HT29 cell death induced by E. histolytica. Suppression of Rac1 by siRNA significantly inhibited Entamoeba-induced cell death. Moreover, knockdown of NOX1 by siRNA, effectively inhibited E. histolytica-triggered DNA fragmentation in HT29 cells. These results suggest that NOX1-derived ROS is required for apoptotic cell death in HT29 colon epithelial cells induced by E. histolytica.
authors: Department of Environmental Medical Biology, Yonsei University College of Medicine, Seoul 120-752, Korea.
authors: Kyeong Ah
authors: KA
authors: Kim
authors: Ju Young
authors: JY
authors: Kim
authors: Young Ah
authors: YA
authors: Lee
authors: Arim
authors: A
authors: Min
authors: Young Yil
authors: YY
authors: Bahk
authors: Myeong Heon
authors: MH
authors: Shin
mesh_terms: D016923:Cell Death; D002460:Cell Line; D004748:Entamoeba histolytica / Q000472:pathogenicity*; D004847:Epithelial Cells / Q000378:metabolism / Q000469:parasitology* / Q000502:physiology*; D054884:Host-Pathogen Interactions; D006801:Humans; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism / Q000633:toxicity*; D015398:Signal Transduction
chemical_list: D017382:Reactive Oxygen Species; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases; C402799:NOX1 protein, human
keywords: Entamoeba histolytica; HT29 colon epithelial cell; NADPH oxidase 1 (NOX1); host cell death; reactive oxygen species (ROS)