The cathepsin B inhibitor, z-FA-CMK is toxic and readily induced cell death in human T lymphocytes.
The cathepsin B inhibitor, benzyloxycarbonyl-phenylalanine-alanine-chloromethylketone (z-FA-CMK) was found to be toxic and readily induced cell death in the human T cell line, Jurkat, whereas two other analogs benzyloxycarbonyl-phenylalanine-alanine-fluoromethylketone (z-FA-FMK) and benzyloxycarbonyl-phenylalanine-alanine-diazomethylketone (z-FA-DMK) were not toxic. The toxicity of z-FA-CMK requires not only the CMK group, but also the presence of alanine in the P1 position and the benzyloxycarbonyl group at the N-terminal. Dose-response studies showed that lower concentrations of z-FA-CMK induced apoptosis in Jurkat T cells whereas higher concentrations induced necrosis. In z-FA-CMK-induced apoptosis, both initiator caspases (-8 and -9) and effector caspases (-3, -6 and -7) were processed to their respective subunits in Jurkat T cells. However, only the pro-form of the initiator caspases were reduced in z-FA-CMK-induced necrosis and no respective subunits were apparent. The caspase inihibitor benzyloxycarbonyl-valine-alanine-aspartic acid-(O-methyl)-fluoromehylketone (z-VAD-FMK) inhibits apoptosis and caspase processing in Jurkat T cells treated with low concentration of z-FA-CMK but has no effect on z-FA-CMK-induced necrosis and the loss of initiator caspases. This suggests that the loss of initiator caspases in Jurkat T cells during z-FA-CMK-induced necrosis is not a caspase-dependent process. Taken together, we have demonstrated that z-FA-CMK is toxic to Jurkat T cells and induces apoptosis at low concentrations, while at higher concentrations the cells die of necrosis.
School of Science, Monash University Sunway Campus, Jalan Lagoon Selatan, 46150 Bandar Sunway, Selangor Darul Ehsan, Malaysia.
K Y
KY
Liow
S C
SC
Chow
D000590:Amino Acid Chloromethyl Ketones / Q000633:toxicity*; D002401:Cathepsin B / Q000037:antagonists & inhibitors* / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D019169:Jurkat Cells; D018696:Neuroprotective Agents / Q000494:pharmacology; D016176:T-Lymphocyte Subsets / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology
D000590:Amino Acid Chloromethyl Ketones; D018696:Neuroprotective Agents; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C533912:CTSB protein, human; D002401:Cathepsin B
Apoptosis; Caspases; Necrosis; T cells; z-FA-CMK; z-FA-FMK