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Autophagy protects PC12 cells against deoxynivalenol toxicity via the Class III PI3K/beclin 1/Bcl-2 pathway

Deoxynivalenol (DON) is a major mycotoxin from the trichothecene family of mycotoxins produced by Fusarium fungi. It can cause a variety of adverse effects on human and farm animal health. Here, we determined the effect of DON on the Class III phosphatidylinositol 3-kinase (PIK3C3)/beclin 1/B cell lymphoma-2 (Bcl-2) pathway in PC12 cells and the relationship between autophagy and apoptosis. The effects of DON were evaluated based on the apoptosis ratio; the typical indicators of autophagy, including cellular morphology, acridine orange- and monodansylcadaverine-labeled vacuoles, green fluorescent protein-microtubule associated protein 1 light chain 3 (LC3) localization, and LC3 immunofluorescence; and the expression of key autophagy-related genes and proteins, that is, PIK3C3, beclin 1, Bcl-2, LC3, and p62. The relationship between autophagy and apoptosis was analyzed by western blot analysis and flow cytometry. DON-induced PC12 cell morphological changes and autophagy significantly. PIK3C3, beclin 1, and LC3 increased in tandem with the DON concentration used; Bcl-2 and p62 expression decreased as DON concentrations increased. Moreover, the PIK3C3/beclin 1/Bcl-2 signaling pathway played a role in DON-induced autophagy. Our findings suggest that DON can induce autophagy by activating the PIK3C3/beclin 1/Bcl-2 signaling pathway and that autophagy may play a positive role in reducing DON-induced apoptosis.

Toxicological mechanisms and potential health effects of deoxynivalenol and nivalenol

Produced by the mould genus Fusarium, the type B trichothecenes include deoxynivalenol (DON), nivalenol (NIV) and their acetylated precursors. These mycotoxins often contaminate cereal staples, posing a potential threat to public health that is still incompletely understood. Understanding the mechanistic basis by which these toxins cause toxicity in experimental animal models will improve our ability to predict the specific thresholds for adverse human effects as well as the persistence and reversibility of these effects. Acute exposure to DON and NIV causes emesis in susceptible species such as pigs in a manner similar to that observed for certain bacterial enterotoxins. Chronic exposure to these mycotoxins at low doses causes growth retardation and immunotoxicity whereas much higher doses can interfere with reproduction and development. Pathophysiological events that precede these toxicities include altered neuroendocrine responses, upregulation of proinflammatory gene expression, interference with growth hormone signalling and disruption of gastrointestinal tract permeability. The underlying molecular mechanisms involve deregulation of protein synthesis, aberrant intracellular cell signalling, gene transactivation, mRNA stabilisation and programmed cell death. A fusion of basic and translational research is now needed to validate or refine existing risk assessments and regulatory standards for DON and NIV. From the perspective of human health translation, biomarkers have been identified that potentially make it possible to conduct epidemiological studies relating DON consumption to potential adverse human health effects. Of particular interest will be linkages to growth retardation, gastrointestinal illness and chronic autoimmune diseases. Ultimately, such knowledge can facilitate more precise science-based risk assessment and management strategies that protect consumers without reducing availability of critical food sources.