Molecular mechanism of satratoxin-induced apoptosis in HL-60 cells: activation of caspase-8 and caspase-9 is involved in activation of caspase-3.
Satratoxins have been recognized as potential immunomodulatory agents in outbreaks of building-related illness. Here we report that satratoxin G-treated human leukemia HL-60 cells underwent apoptosis through the action of caspase-3 which was activated by both caspase-8 and caspase-9. Western blot analysis of caspase-3 in the satratoxin G-treated cells apparently indicated the appearance of a catalytically active fragment of 17 kDa. Increased caspase-3 activity was also detected by using a fluorogenic substrate, DEVD-AMC. Next, exposure to satratoxin G led to cleavage of PARP from its native 116 kDa form to a 85 kDa product. Moreover, DFF-45/ICAD were cleaved into a 12.5 kDa fragment via satratoxin G treatment. Enzymic assay on IETD-AMC revealed that caspase-8 is strongly activated by exposure to satratoxin G while T-2 toxin (T-2) could not activate caspase-8 at an early stage of apoptosis. Furthermore, satratoxin G caused a release of cytochrome c from mitochondria into the cytosol and increased the activity of caspase-9 against LEHD-AMC. These findings indicate that satratoxin G-induced apoptosis involves activation of caspase-3 and DFF-40/CAD through both activation of caspase-8 and cytosolic accumulation of cytochrome c along with activation of caspase-9.
Nagase
Masahiro
M
Department of Life Sciences, Faculty of Agriculture, Kagawa University, 2393 Ikenobe, Miki, Kagawa 761-0795, Japan. nagase@ag.kagawa-u.ac.jp
Shiota
Tetsuya
T
Tsushima
Akiko
A
Murshedul Alam
Mohammad
M
Fukuoka
Satoshi
S
Yoshizawa
Takumi
T
Sakato
Nobuo
N
D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D003374:Coumarins; D003574:Cytochrome c Group / Q000378:metabolism; D003851:Deoxyribonucleases / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005456:Fluorescent Dyes; D018922:HL-60 Cells; D006801:Humans; D007166:Immunosuppressive Agents / Q000633:toxicity; D009842:Oligopeptides; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D000075223:Poly-ADP-Ribose Binding Proteins; D018877:Sick Building Syndrome / Q000209:etiology; D013191:Stachybotrys / Q000472:pathogenicity; D014255:Trichothecenes / Q000633:toxicity*
D003374:Coumarins; D003574:Cytochrome c Group; D005456:Fluorescent Dyes; D007166:Immunosuppressive Agents; D009842:Oligopeptides; D000075223:Poly-ADP-Ribose Binding Proteins; D014255:Trichothecenes; C102580:acetyl-aspartyl-glutamyl-valyl-aspartyl-amino-4-methylcoumarin; C028268:satratoxin G; D011065:Poly(ADP-ribose) Polymerases; C113696:DFFB protein, human; D003851:Deoxyribonucleases; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases