Korean J Parasitol.  2014 Oct;52(5):459-469. 10.3347/kjp.2014.52.5.459.

Degradation of the Transcription Factors NF-kappaB, STAT3, and STAT5 Is Involved in Entamoeba histolytica-Induced Cell Death in Caco-2 Colonic Epithelial Cells

• Kim KA
• Min A
• Lee YA
• Shin MH

• KMID: 1792210
• DOI: http://doi.org/10.3347/kjp.2014.52.5.459

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-kappaB (p65) in Caco-2 cells. However, IkappaB, an inhibitor of NF-kappaB, was not cleaved in Caco-2 cells following adherence of E. histolytica. Entamoeba-induced cleavage of STAT proteins and NF-kappaB 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-kappaB and STATs in colonic epithelial cells, which ultimately accelerates cell death.

Keyword

Entamoeba histolytica; m-calpain; Caco-2; NF-kappaB; STAT

MeSH Terms

Caco-2 Cells
Calcium-Binding Proteins
Calpain/genetics/metabolism
Caspase 3/genetics/metabolism
Caspases
*Cell Death
Colon/cytology
Entamoeba histolytica/*physiology
Epithelial Cells/cytology/parasitology
Humans
I-kappa B Proteins/metabolism
Intestinal Mucosa/cytology
NF-kappa B/genetics/*metabolism
RNA Interference
RNA, Small Interfering
STAT3 Transcription Factor/genetics/*metabolism
STAT5 Transcription Factor/genetics/*metabolism
Signal Transduction
Calcium-Binding Proteins
Calpain
Caspase 3
Caspases
I-kappa B Proteins
NF-kappa B
RNA, Small Interfering
STAT3 Transcription Factor
STAT5 Transcription Factor