Gliotoxin induces apoptosis in cultured macrophages via production of reactive oxygen species and cytochrome c release without mitochondrial depolarization.
The cytotoxicity and its underlying mechanisms induced by gliotoxin (GT), an immunosuppressive agent, in macrophages are poorly understood. We report here that GT induced a rapid apoptosis (DNA fragmentation and hypodiploid nuclei obtained within 4 hrs of treatment) in murine macrophages PU5-1.8 in a dose-dependent and cell cycle-independent manner. The GT-induced apoptosis was suppressed by z-Asp, z-VAD-fmk and antioxidants suggesting that production of reactive oxygen species (ROS) and activation of caspases were important in this process. Also, release of cytochrome c from mitochondria was found to be an early event (within 1 hr) after addition of GT (250 ng/ml) and its presence in the cytosol was sufficient to elicit apoptosis. Interestingly, the release of cytochrome c was not accompanied by a reduction in the mitochondrial membrane potential (psi m) as determined by several psi m-sensitive fluorescent indicators. Taken together, our results indicate that GT is a potent apoptotic agent in PU5-1.8 cells and the loss of psi m is not a universal early marker for apoptosis.
Suen
Y K
YK
Department of Biochemistry, Chinese University of Hong Kong, Shatin, Hong Kong, China.
Fung
K P
KP
Lee
C Y
CY
Kong
S K
SK
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D003574:Cytochrome c Group / Q000378:metabolism*; D004996:Ethidium / Q000031:analogs & derivatives*; D005434:Flow Cytometry; D005912:Gliotoxin / Q000494:pharmacology*; D006861:Hydrogen Peroxide; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012603:Scopoletin
D000975:Antioxidants; D003574:Cytochrome c Group; D007166:Immunosuppressive Agents; D017382:Reactive Oxygen Species; C067883:dihydroethidium; D005912:Gliotoxin; D006861:Hydrogen Peroxide; D004996:Ethidium; D012603:Scopoletin