T-2 toxin induces apoptosis in differentiated murine embryonic stem cells through reactive oxygen species-mediated mitochondrial pathway
Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, Academy of Military Medical Sciences, 20 Dongdajie Street, Fengtai District, Beijing, 100071, People's Republic of China. Apoptosis
(Impact Factor: 3.69).
05/2012; 17(8):895-907. DOI: 10.1007/s10495-012-0724-3
T-2 toxin, a member of the trichothecene mycotoxin family produced by the Fusarium fungi, has been shown to exert a variety of toxic effects on multiple targets in vivo. However, the embryonic toxicity of T-2 toxin in vitro remains unclear. In the present study, two permanent cell lines, embryonic stem cells (ES cells D3) and fibroblast 3T3 cells, were used to evaluate T-2 toxin toxicity. Differentiated mouse ES cells were cultivated as embryoid bodies along with T-2 toxin at different concentrations (0.5, 1, and 2 ng/ml) for 24 h. The increases in cellular reactive oxygen species (ROS), lipid and DNA oxidative damage, and loss of mitochondrial transmembrane potential were observed at 1 and 2 ng/ml concentrations. Flow cytometry showed that T-2 toxin induced cell cycle arrest and apoptosis. Furthermore, T-2 toxin opened the mitochondrial permeability transition pore, caused the release of cytochrome c from mitochondria and induced the upregulation of p53, caspase-9, caspase-3 expression and increased the ratio of Bax/Bcl-2. However, T-2 toxin-induced oxidative damage and apoptosis in differentiated ES cells decreased significantly in the presence of the antioxidant Trolox. Taken together, these results demonstrate that T-2 toxin induces oxidative stress and apoptosis in differentiated murine ES cells, and ROS-mediated mitochondrial pathway plays an important role in T-2 toxin induced apoptosis.
Available from: Xu Wang
- "ROS generation and GSH depletion, together with lipid peroxidation in differentiated murine embryonic stem cells, have confirmed that oxidative stress is an underlying mechanism of T-2 toxin cytotoxicity (Fang et al. 2012). In the studies of wu et al. (2011a) as well as those of Fang et al. (2012), T-2 toxin-induced apoptosis was not completely blocked by the inhibitor, thus the authors have suggested that other pathways may also be involved in the regulation of apoptosis. Indeed, another caspase-independent apoptosis-inducing factor (AIF) pathway is also involved in T-2 toxin-induced apoptosis (chaudhari et al. 2009b). "
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ABSTRACT: Trichothecenes are a large family of structurally related toxins mainly produced by Fusarium genus. Among the trichothecenes, T-2 toxin and deoxynivalenol (DON) cause the most concern due to their wide distribution and highly toxic nature. Trichothecenes are known for their inhibitory effect on eukaryotic protein synthesis, and oxidative stress is one of their most important underlying toxic mechanisms. They are able to generate free radicals, including reactive oxygen species, which induce lipid peroxidation leading to changes in membrane integrity, cellular redox signaling, and in the antioxidant status of the cells. The mitogen-activated protein kinases signaling pathway is induced by oxidative stress, which also induces caspase-mediated cellular apoptosis pathways. Several new metabolites and novel metabolic pathways of T-2 toxin have been discovered very recently. In human cell lines, HT-2 and neosolaniol (NEO) are the major metabolites of T-2 toxin. Hydroxylation on C-7 and C-9 are two novel metabolic pathways of T-2 toxin in rats. The metabolizing enzymes CYP3A22, CYP3A29, and CYP3A46 in pigs, as well as the enzymes CYP1A5 and CYP3A37 in chickens, are able to catalyze T-2 toxin and HT-2 toxin to form the C-3′–OH metabolites. Similarly to carboxylesterase, CYP3A29 possesses the hydrolytic ability in pigs to convert T-2 toxin to NEO. T-2 toxin is able to down- or upregulate cytochrome P-450 enzymes in different species. The metabolism of DON in humans is region-dependent. Free DON and DON-glucuronide are considered to be the biomarkers for humans. The masked mycotoxin DON-3-β-d-glucoside can be hydrolyzed to free DON in the body. This review will provide useful information on the progress of oxidative stress as well as on the metabolism and the metabolizing enzymes of T-2 toxin and DON. Moreover, the literature will throw light on the blind spots of metabolism and toxicological studies in trichothecenes that have to be explored in the future.
Available from: PubMed Central
- "Caspase-8 was activated at about 24 h, but Caspase-9 was about 16 h (Figure 5C). These results indicated that the apoptosis induced by T-2 toxin was probably through mitochondrial pathway, which coincided with the previous reports , . "
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ABSTRACT: T-2 toxin is known to induce apoptosis in mammalian cells. The mechanism of apoptosis induced by T-2 toxin has been proposed to be linked with oxidative stress and mitochondrial pathway. In the current study, the toxic effect of T-2 on Hela, Bel-7402, and Chang liver cells was examined in dose-dependent and time-dependent manner by MTT assay. Caspase-3 was found to be up-regulated under T-2 toxin stress, which suggested that T-2 toxin induced cell apoptosis. Endogenous GSH and MDA levels in all three cell lines were found down- and up-regulated respectively, which indicated the link between toxic effect of T-2 toxin and intracellular oxidative stress. It was also found by MTT assay that NAC, which maintained the level of GSH in cells, could protect cells from death. Western-blot result showed that the level of both activated Caspase-8 and Caspase-9 increased when cells were treated by T-2 toxin. Caspase-9 was found to be activated earlier than Caspase-8. It was also found that p53 was up-regulated under T-2 toxin stress in the study. These results implied that the effect of T-2 toxin on cells was apoptosis rather than necrosis, and it was probably induced through mitochondrial pathway. To the best of our knowledge, the present study is the first to show that JunD is down-regulated in T-2 toxin induced apoptosis. By construction of an over-expression vector for the JunD gene, we observed that the survival ratio of JunD over-expressed cells obviously increased under T-2 toxin stress. These results suggested that the mechanism of T-2 induced cell death was closely connected with oxidative stress, and that JunD plays an important role in the defensive process against T-2 toxin stress.
Available from: Mehdi Djelloul
- "Finally, we tested the hypothesis that T-2 toxin-induced sickness behavior could be explained by an increased production of reactive oxygen species (ROS). T-2 toxin can cause in vitro generation of ROS as well as an up-regulation of antioxidant enzymes (SOD, CAT) in different cellular models (Chaudhari et al., 2009; He et al., 2012; Fang et al., 2012). Dermal or subcutaneous T-2 toxin treatments induce a time-dependent brain ROS production i.e., 1, 3 and 7 days post-treatment (Chaudhary and Rao, 2010). "
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ABSTRACT: T-2 toxin is one of the most toxic Fusarium-derived trichothecenes found on cereals and constitutes a widespread contaminant of agricultural commodities as well as commercial foods. Low doses toxicity is characterized by reduced weight gain. To date, the mechanisms by which this mycotoxin profoundly modifies feeding behavior remain poorly understood and more broadly the effects of T-2 toxin on the central nervous system (CNS) have received limited attention. Through an extensive characterization of sickness-like behavior induced by T-2 toxin, we showed that its per os (p.o.) administration affects not only feeding behavior but also energy expenditure, glycaemia, body temperature and locomotor activity. Using c-Fos expression mapping, we identified the neuronal structures activated in response to T-2 toxin and observed that the pattern of neuronal populations activated by this toxin resembled that induced by inflammatory signals. Interestingly, part of neuronal pathways activated by the toxin NUCB-2/nesfatin-1 expressing neurons. Unexpectedly, while T-2 toxin induced a strong peripheral inflammation, the brain exhibited limited inflammatory response at a time point when anorexia was ongoing. Unilateral vagotomy partly reduced T-2 toxin-induced brainstem neuronal activation. On the other hand, intracerebroventricular (icv) T-2 toxin injection resulted in a rapid (<1 h) reduction in food intake. Thus, we hypothesized that T-2 toxin could signal to the brain through neuronal and/or humoral pathways. The present work provides the first demonstration that T-2 toxin modifies feeding behavior by interfering with central neuronal networks devoted to central energy balance. Our results, with a particular attention to peripheral inflammation, strongly suggest that inflammatory mediators partake in the T-2 toxin- induced anorexia and other symptoms. In view of the broad human and breeding animal exposure to T-2 toxin, this new mechanism may lead to reconsider the impact of the consumption of this toxin on human health.
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