title: Calpain-dependent calpastatin cleavage regulates caspase-3 activation during apoptosis of Jurkat T cells induced by Entamoeba histolytica.
abstract: In this study, we investigated whether there is a signalling interaction between calpain and caspase-3 during apoptosis in Jurkat T cells by Entamoeba histolytica. When Jurkat cells were co-incubated with E. histolytica, phosphatidylserine externalisation and DNA fragmentation markedly increased compared with results for cells incubated with medium alone. In addition, E. histolytica strongly induced cleavage of caspases-3, -6, -7 and poly(ADP-ribose) polymerase. A rise in intracellular calcium levels and activation of calpain were seen in Jurkat cells after exposure to E. histolytica. Pretreatment of Jurkat cells with calpain inhibitor calpeptin effectively blocked E. histolytica-triggered cleavage of caspase-3 as well as calpain. In contrast, pan-caspase inhibitor did not affect E. histolytica-induced calpain activation. In addition, incubation with E. histolytica resulted in multiple fragmented bands of calpastatin, which is an endogenous inhibitor of calpain, in Jurkat T cells. Moreover, Entamoeba-induced calpastatin degradation was dramatically suppressed by pretreatment with calpeptin, but not by z-VAD-fmk. Entamoeba-induced DNA fragmentation was strongly retarded by z-VAD-fmk, but not calpeptin. Our results suggest that calpain-mediated calpastatin degradation plays a crucial role in regulation of caspase-3 activation during apoptosis of Jurkat T cells by E. histolytica.
authors.affiliation: Department of Parasitology, Institute of Tropical Medicine, and Brain Korea 21 for Medical Science, Yonsei University College of Medicine, 134 Sinchon dong, Seodaemun gu, Seoul 120-752, Republic of Korea.
authors.forename: Kyeong Ah
authors.initials: KA
authors.lastname: Kim
authors.forename: Young Ah
authors.initials: YA
authors.lastname: Lee
authors.forename: Myeong Heon
authors.initials: MH
authors.lastname: Shin
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics*; D002154:Calpain / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism*; D061945:Caspase Inhibitors; D053837:DNA Cleavage; D004151:Dipeptides / Q000494:pharmacology; D004748:Entamoeba histolytica / Q000378:metabolism*; D004749:Entamoebiasis / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D004789:Enzyme Activation; D006790:Host-Parasite Interactions; D006801:Humans; D019169:Jurkat Cells; D010274:Parasitology / Q000379:methods; D013601:T-Lymphocytes / Q000201:enzymology* / Q000473:pathology
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D002135:Calcium-Binding Proteins; D061945:Caspase Inhibitors; D004151:Dipeptides; C484771:benzyloxycarbonyl-valyl-aspartic acid fluoromethyl ketone; C071482:calpeptin; C033668:calpastatin; D002154:Calpain; D053148:Caspase 3; D002118:Calcium