O-deGlcNAcylation is required for Entamoeba histolytica-induced HepG2 cell death

Abstract

Entamoeba histolytica is an enteric tissue-invading protozoan parasite that causes amoebic colitis and occasionally liver abscess in humans. E. histolytica can induce host-cell apoptosis by initiating various intracellular signaling mechanisms closely associated with tissue pathogenesis and parasitic immune evasion. O-GlcNAcylation, similar to phosphorylation, is involved in various cell-signaling processes, including apoptosis and proliferation, with O-GlcNAc addition and removal regulated by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), respectively. However, whether O-GlcNAc alterations in host cells affect E. histolytica-induced cell death and which signal molecules participate in E. histolytica-induced deglycosylation remain unknown. In this study, co-incubation of HepG2 cells with E. histolytica increased DNA fragmentation and LDH release as compared with control cells. Additionally, Gal-lectin-mediated amoebic adherence of live trophozoites to HepG2 cells decreased O-GlcNAcylated protein levels within 5 min. We also observed a rapid decrease in cellular OGT protein level, but not OGA, in HepG2 cells in a contact-dependent manner. Furthermore, HepG2 pretreatment with OGA inhibitors or OGA siRNA prevented E. histolytica-induced O-deGlcNAcylation, DNA fragmentation, and LDH release. Our results suggested that E. histolytica-induced O-deGlcNAcylation in HepG2 cells was an important process required for hepatocyte cell death induced by E. histolytica adherence.

Keywords: Cell death; Entamoeba histolytica; O-GlcNAc; OGA; OGT.