Induction of apoptosis by disturbing mitochondrial-membrane potential and cleaving PARP in Jurkat T cells through treatment with acetoxyscirpenol mycotoxins.
Paecilomyces tenuipes is a famous Chinese medicinal entomopathogenic fungus that grows within the larvae of silkworms. 4beta-acetoxyscirpendiol (4-MAS), a cytotoxic compound belonging to the scirpenol subfamily of trichothecene mycotoxin, was isolated from Paecilomyces tenuipes. To further elucidate the cytotoxic mechanism of 4-MAS, evidences of its induction of apoptosis, together with the structurally related acetoxyscirpenol moiety mycotoxins (ASMs) such as, 15-acetoxyscirpenol (15-MAS), 4,15-diacetoxyscirpenol (4,15-DAS), and 3alpha-acetyldiacetoxyscirpenol (TAS), in the human Jurkat T cell line were reported herein. In the MTT reduction and time-course cytotoxicity assays for monitoring cell viability, all the four ASMs that were tested exhibited cytotoxicity; single acetoxylation at C-4 of the scirpenol family resulted in relatively weak cytotoxicity, while acetoxylation at C-15 resulted in strong cytotoxicity regardless of the other acetoxylations at the C-3 and/or C-4 positions. Phosphatidylserine externalization was induced by all the ASMs that were treated at an early phase in a time-dependent manner, showing a typical apoptotic phenomenon, not a necrotic one. The ASMs also reduced the mitochondria's inner-membrane potential (deltaPsim) through flow cytometry analysis after staining these with DiOC6, a mitochondria-specific and voltage-dependent dye. Acetoxylation of ASM at C-15 increased deltaPsim disruption, but that at C-3 reduced the deltaPsim. The ASMs that were tested also cleaved 113 kDa PARP to an 89-kDa fragment through Western blot assay, suggesting the activation of caspase-3 and/or caspase-7 in the Jurkat T cell. DNA fragmentation was also observed to have been increased in a time-dependent manner by the ASMs that were tested in Jurkat T cells, resulting in the DNA fragmentation intensity order of 4,15-DAS>15-MAS>TAS>4-MAS. These data indicate that the Jurkat T cells that were treated with ASMs underwent typical cascades of apoptotic cell death.
Lee
Dong Hee
DH
Department of Life Sciences, University of Seoul, Korea.
Park
Taesun
T
Kim
Ha Won
HW
D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D001578:Benzopyrans / Q000633:toxicity*; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D053938:DNA Fragmentation; D005434:Flow Cytometry; D006801:Humans; D007202:Indicators and Reagents; D019169:Jurkat Cells; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects*; D009183:Mycotoxins / Q000633:toxicity*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D051381:Rats; D013329:Structure-Activity Relationship; D013778:Tetrazolium Salts; D013844:Thiazoles
D017304:Annexin A5; D001578:Benzopyrans; D007202:Indicators and Reagents; D009183:Mycotoxins; D013778:Tetrazolium Salts; D013844:Thiazoles; C510382:acetoxyscirpenol; D011065:Poly(ADP-ribose) Polymerases; D020169:Caspases; C022616:thiazolyl blue