Analysis of RIOK2 Functions in Mediating the Toxic Effects of Deoxynivalenol in Porcine Intestinal Epithelial Cells

DON induced DNA damage triggers absence of p53-mediated G2 arrest and apoptosis in IPEC-1 cells

Deoxynivalenol (DON) stands among the prevalent mycotoxins, and usually contaminates cereal foods and animal feed, leading to human and animal clinical poisoning symptoms such as abdominal pain, diarrhea, and vomiting. To date, the mechanism of toxicity of DON in different mammalian cells is not fully elucidated. In this study, we explored the detrimental impacts of DON on porcine intestinal epithelial cells (IPEC-1), serving as a representative model for porcine intestinal epithelial cells. After treating cells with DON for 24 h, DON can significantly inhibit the activity of cells, induce the production of reactive oxygen species (ROS), significantly reduce the content of glutathione and the activity of catalase, and increase the activity of superoxide dismutase and malondialdehyde, leading to an imbalance in intracellular redox status. In addition, DON can induce DNA double-strand breaks, and decrease mitochondrial membrane potential. Furthermore, DON can promote the release of Cyt C through changes in mitochondrial permeability through inhibit the expression of B-cell lymphoma 2 (Bcl-2) proteins, leading to apoptosis through the mitochondrial pathway. On the other hand, we found that DON can cause IPEC-1 cells G2 phase cycle arrest. Different with our pervious study, DON induces cell cycle arrest in the G2 phase only by activating the ATM-Chk2-Cdc 25 C pathway, but cannot regulate the cell cycle arrest via the ATM-p53 pathway. These results indicate that DON can induce the same toxic phenotype in different cells, but its toxic mechanism is different. All these provide a rationale for revealing DON induced cytotoxicity and intestinal diseases.

Deoxynivalenol exposure induces oxidative stress and apoptosis in human keratinocytes via PI3K/Akt and MAPK signaling pathway

Deoxynivalenol (DON) is a mycotoxin frequently occurring in human and animal food worldwide, which raises increasing public health concerns. In the present study, we used human keratinocytes (HaCaT cells) as an in vitro model to explore the cytotoxic effect of DON. The results showed that the cells exhibited varying degrees of damage, including decreased cell number and viability, cell shrinkage and floating, when treated with 0.125, 0.25, and 0.5 μg/mL DON for 6, 12, and 24 h, respectively. Furthermore, exposure to DON for 24 h significantly increased the lactate dehydrogenase (LDH) release and intracellular reactive oxygen species (ROS), and prominently decreased the superoxide dismutase (SOD) and catalase (CAT) activity. Additionally, DON exposure induced mitochondrial damage and cell apoptosis through reducing mitochondrial membrane potential. Then, we performed RNA-sequencing to investigate the molecular changes in HaCaT cells after DON exposure. The RNA-sequencing results revealed that DON exposure altered the gene expression involved in apoptosis, MAPK signaling pathway, and PI3K/Akt signaling pathway. Moreover, DON exposure significantly decreased the mRNA and protein expression of Bcl-2, and increased the mRNA and protein expression of Bax, Caspase 3 and COX-2, the protein expression of PI3K, and the phosphorylation levels of Akt, ERK, p38, and JNK. Taken together, these findings suggest that DON exposure could induce cell damage, oxidative stress, and apoptosis in HaCaT cells through the activation of PI3K/Akt and MAPK pathways.

Nivalenol disrupts mitochondria functions during porcine oocyte meiotic maturation

Oocyte maturation is important for fertility in mammals, since the quality of oocytes directly affects fertilization, embryo attachment and survival. Nivalenol is widely present in nature as a common toxin that contaminates grain and feed, and it has been reported to cause acute toxicity, immunotoxicity, reproductive toxicity and carcinogenic effects. In this study, we explored the impact of nivalenol on the porcine oocyte maturation and its possible mechanisms. The extrusion of the first polar body was significantly inhibited after incubating oocytes with nivalenol. Meanwhile, nivalenol exposure led to the abnormal distribution of mitochondria, aberrant calcium concentration and the reduction of membrane potential caused a significant decrease in the capacity of mitochondria to generate ATP. In addition, nivalenol induced oxidative stress, and the level of ROS was significantly increased in the nivalenol-treated group, which was confirmed by the perturbation of oxidative stress-related genes. We found that nivalenol-treated oocytes showed positive Annexin-V and γH2A.X signals, indicating the occurrence of apoptosis and DNA damage. In all, our data suggest that nivalenol disrupted porcine oocyte maturation through its effects on mitochondria-related oxidative stress, apoptosis and DNA damage.