Résumé
Bovine lactoferricin (LfcinB) is a cationic antimicrobial peptide that kills Jurkat T-leukemia cells by the mitochondrial pathway of apoptosis. However, the process by which LfcinB triggers mitochondria-dependent apoptosis is not well understood. Here, we show that LfcinB-induced apoptosis in Jurkat T-leukemia cells was preceded by LfcinB binding to, and progressive permeabilization of the cell membrane. Colloidal gold electron microscopy revealed that LfcinB entered the cytoplasm of Jurkat T-leukemia cells prior to the onset of mitochondrial depolarization. LfcinB was not internalized by endocytosis because endocytosis inhibitors did not prevent LfcinB-induced cytotoxicity. Furthermore, intracellular delivery of LfcinB via fusogenic liposomes caused the death of Jurkat T-leukemia cells, as well as normal human fibroblasts. Collectively, these findings suggest that LfcinB caused damage to the cell membrane that allowed LfcinB to enter the cytoplasm of Jurkat T-leukemia cells and mediate cytotoxicity. In addition, confocal microscopy showed that intracellular LfcinB co-localized with mitochondria in Jurkat T-leukemia cells, while flow cytometry and colloidal gold electron microscopy showed that LfcinB rapidly associated with purified mitochondria. Furthermore, purified mitochondria treated with LfcinB rapidly lost transmembrane potential and released cytochrome c. We conclude that LfcinB-induced apoptosis in Jurkat T-leukemia cells resulted from cell membrane damage and the subsequent disruption of mitochondrial membranes by internalized LfcinB.
Langue d'origine | English |
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Pages (de-à) | 2634-2650 |
Nombre de pages | 17 |
Journal | Experimental Cell Research |
Volume | 313 |
Numéro de publication | 12 |
DOI | |
Statut de publication | Published - juill. 15 2007 |
Note bibliographique
Funding Information:This work was supported by grants to D. H. from the Natural Sciences and Engineering Council of Canada (NSERC), the Dairy Farmers of Canada, and the Leukemia and Lymphoma Society of Canada, and to R.D. from the Canadian Institutes of Health Research and NSERC. A.R. is supported by a Cancer Research Training Award with funding from the Canadian Cancer Society. D.T. is supported by a Cancer Research Training Program Award with funding from the Dalhousie Cancer Research Program. J.M. was supported by a Graduate Studentship from the Nova Scotia Health Research Foundation. We thank M. Trevors and G. Faulkner for assistance with electron microscopy.
ASJC Scopus Subject Areas
- Cell Biology
PubMed: MeSH publication types
- Journal Article
- Research Support, Non-U.S. Gov't