Satratoxin G interaction with 40S and 60S ribosomal subunits precedes apoptosis in the macrophage

Journal Article · Mon Jun 01 04:00:00 EDT 2009 · Toxicology and Applied Pharmacology

DOI:https://doi.org/10.1016/j.taap.2009.03.006· OSTI ID:21272563

Bae, Hee Kyong ^[1]; Shinozuka, Junko ^[2]; Islam, Zahidul ^[1]; Pestka, James J ^[1]

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1. Department of Food Science and Human Nutrition, 234 G.M. Trout Building, Michigan State University, East Lansing, MI 48824-1224 (United States)
2. Safety Research Laboratory, Mitsubishi Tanabe Pharma Corporation, 2-50, Kawagishi, 2-Chome, Toda, Saitama, 335-8505 (Japan)

Satratoxin G (SG) and other macrocyclic trichothecene mycotoxins are potent inhibitors of eukaryotic translation that are potentially immunosuppressive. The purpose of this research was to test the hypothesis that SG-induced apoptosis in the macrophage correlates with binding of this toxin to the ribosome. Exposure of RAW 264.7 murine macrophages to SG at concentrations of 10 to 80 ng/ml induced DNA fragmentation within 4 h that was indicative of apoptosis. To relate these findings to ribosome binding of SG, RAW cells were exposed to different toxin concentrations for various time intervals, ribosomal fractions isolated by sucrose density gradient ultracentrifugation and resultant fractions analyzed for SG by competitive ELISA. SG was found to specifically interact with 40S and 60S ribosomal subunits as early as 5 min and that, at high concentrations or extended incubation times, the toxin induced polysome disaggregation. While co-incubation with the simple Type B trichothecene DON had no effect on SG uptake into cell cytoplasm, it inhibited SG binding to the ribosome, suggesting that the two toxins bound to identical sites and that SG binding was reversible. Although both SG and DON induced mobilization of p38 and JNK 1/2 to the ribosome, phosphorylation of ribosomal bound MAPKs occurred only after DON treatment. SG association with the 40S and 60S subunits was also observed in the PC-12 neuronal cell model which is similarly susceptible to apoptosis. To summarize, SG rapidly binds small and large ribosomal subunits in a concentration- and time-dependent manner that was consistent with induction of apoptosis.

• OSTI ID: 21272563
• Journal Information: Toxicology and Applied Pharmacology, Journal Name: Toxicology and Applied Pharmacology Journal Issue: 2 Vol. 237; ISSN TXAPA9; ISSN 0041-008X
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
APOPTOSIS
CYTOPLASM
DNA
ENZYME IMMUNOASSAY
HYPOTHESIS
IMMUNOSUPPRESSION
INCUBATION
INTERACTIONS
MACROPHAGES
MYCOTOXINS
PHOSPHORYLATION
RIBOSOMES
SACCHAROSE
TIME DEPENDENCE
ULTRACENTRIFUGATION