Thai Acanthamoeba isolate (T4) induced apoptotic death in neuroblastoma cells via the Bax-mediated pathway.
A Thai Acanthamoeba isolate named AS recovered from a corneal scraping of a keratitis patient was genotypically determined as T4. AS trophozoites were used for studying Acanthamoeba-induced apoptosis in mouse neuroblastoma NA cells during in vitro co-cultivation. The Acanthamoeba-exposed NA cells showed signs of apoptosis including cell shrinkage, nuclear condensation and DNA fragmentation. The effect was confirmed by DNA laddering electrophoresis. Involvement of caspase enzymes and mitochondrial pro- and anti-apoptotic proteins (Bax and Bcl-2) in AS-induced apoptosis was determined. The use of Z-VAD-FMK, a pan-caspase inhibitor, significantly reduced the apoptotic effect, while Bax/Bcl-2 ratio analysis showed a significant increase in the expression of apoptotic proteins in AS-exposed NA cells. These results strongly indicated that apoptosis induced by AS trophozoites is caspase-dependent and is mediated by over-expression of pro-apoptotic proteins in the mitochondrial pathway. This is the first report on the role of Bax in mediating apoptosis induced by Acanthamoeba.
Chusattayanond
Araya Dharmkrong-at
AD
Department of Microbiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand. scacs@mahidol.ac.th
Boonsilp
Siriphan
S
Kasisit
Jitra
J
Boonmee
Atsadang
A
Warit
Saradee
S
D000048:Acanthamoeba / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000472:pathogenicity*; D000818:Animals; D017209:Apoptosis; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D005838:Genotype; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009447:Neuroblastoma / Q000378:metabolism / Q000473:pathology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013785:Thailand; D053058:Trophozoites / Q000254:growth & development; D051028:bcl-2-Associated X Protein / Q000378:metabolism*
D061945:Caspase Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D020169:Caspases