title: Degradation of the transcription factors NF-κB, STAT3, and STAT5 is involved in Entamoeba histolytica-induced cell death in Caco-2 colonic epithelial cells.
abstract: Entamoeba histolytica is a tissue-invasive protozoan parasite causing dysentery in humans. During infection of colonic tissues, amoebic trophozoites are able to kill host cells via apoptosis or necrosis, both of which trigger IL-8-mediated acute inflammatory responses. However, the signaling pathways involved in host cell death induced by E. histolytica have not yet been fully defined. In this study, we examined whether calpain plays a role in the cleavage of pro-survival transcription factors during cell death of colonic epithelial cells, induced by live E. histolytica trophozoites. Incubation with amoebic trophozoites induced activation of m-calpain in a time- and dose-dependent manner. Moreover, incubation with amoebae resulted in marked degradation of STAT proteins (STAT3 and STAT5) and NF-κB (p65) in Caco-2 cells. However, IκB, an inhibitor of NF-κB, was not cleaved in Caco-2 cells following adherence of E. histolytica. Entamoeba-induced cleavage of STAT proteins and NF-κB was partially inhibited by pretreatment of cells with a cell-permeable calpain inhibitor, calpeptin. In contrast, E. histolytica did not induce cleavage of caspase-3 in Caco-2 cells. Furthermore, pretreatment of Caco-2 cells with a calpain inhibitor, calpeptin (but not the pan-caspase inhibitor, z-VAD-fmk) or m-calpain siRNA partially reduced Entamoeba-induced DNA fragmentation in Caco-2 cells. These results suggest that calpain plays an important role in E. histolytica-induced degradation of NF-κB and STATs in colonic epithelial cells, which ultimately accelerates cell death.
authors.affiliation: Department of Environmental Medical Biology, Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea.
authors.forename: Kyeong Ah
authors.initials: KA
authors.lastname: Kim
authors.affiliation: Department of Environmental Medical Biology, Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea.
authors.forename: Arim
authors.initials: A
authors.lastname: Min
authors.affiliation: Department of Environmental Medical Biology, Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea.
authors.forename: Young Ah
authors.initials: YA
authors.lastname: Lee
authors.affiliation: Department of Environmental Medical Biology, Institute of Tropical Medicine, Yonsei University College of Medicine, Seoul 120-752, Korea.
authors.forename: Myeong Heon
authors.initials: MH
authors.lastname: Shin
mesh_terms: D018938:Caco-2 Cells; D002135:Calcium-Binding Proteins; D002154:Calpain / Q000235:genetics / Q000378:metabolism; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D020169:Caspases; D016923:Cell Death; D003106:Colon / Q000166:cytology; D004748:Entamoeba histolytica / Q000502:physiology*; D004847:Epithelial Cells / Q000166:cytology / Q000469:parasitology; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D007413:Intestinal Mucosa / Q000166:cytology; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D050799:STAT5 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D002135:Calcium-Binding Proteins; D020672:I-kappa B Proteins; D016328:NF-kappa B; D034741:RNA, Small Interfering; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D050799:STAT5 Transcription Factor; C033668:calpastatin; D002154:Calpain; D053148:Caspase 3; D020169:Caspases
keywords: Caco-2; Entamoeba histolytica; NF-κB; STAT; m-calpain