Paraquat toxicity is attenuated by 4-phenylbutyrate-induced phosphorylation of ERK2 via PI3K in A549 cells

Analysis of abnormal expression of signaling pathways in PQ-induced acute lung injury in SD rats based on RNA-seq technology

Background: Paraquat (PQ) plays an important role in agricultural production due to its highly effective herbicidal effect. However, it has led to multiple organ failure in those who have been poisoned, with damage most notable in the lungs and ultimately leading to death. Because of little research has been performed at the genetic level, and therefore, the specific genetic changes caused by PQ exposure are unclear.Methods: Paraquat poisoning model was constructed in Sprague Dawley (SD) rats, and SD rats were randomly divided into Control group, paraquat (PQ) poisoning group and Anthrahydroquinone-2,6-disulfonate (AH2QDS) treatment group. Then, the data was screened and quality controlled, compared with reference genes, optimized gene structure, enriched at the gene expression level, and finally, signal pathways with significantly different gene enrichment were screened.Results: This review reports on lung tissues from paraquat-intoxicated Sprague Dawley (SD) rats that were subjected to RNA-seq, the differentially expressed genes were mainly enriched in PI3K-AKT, cGMP-PKG, MAPK, Focal adhesion and other signaling pathways.Conclusion: The signaling pathways enriched with these differentially expressed genes are summarized, and the important mechanisms mediated through these pathways in acute lung injury during paraquat poisoning are outlined to identify important targets for AH2QDS treatment of acute lung injury due to paraquat exposure, information that will be used to support a subsequent in-depth study on the mechanism of PQ action.

The herbicide paraquat-induced molecular mechanisms in the development of acute lung injury and lung fibrosis

The herbicide paraquat (PQ; 1,1'-dimethyl-4,4'-bipyridylium dichloride) is a highly toxic organic heterocyclic herbicide that has been widely used in agricultural settings. Since its commercial introduction in the early 1960s, numerous cases of fatal PQ poisonings attributed to accidental and/or intentional ingestion of PQ concentrated formulations have been reported. The clinical manifestations of the respiratory system during the acute phase of PQ poisoning mainly include acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), followed by pulmonary fibrosis in a later phase. The focus of this review is to summarize the most recent publications related to PQ-induced lung toxicity as well as the underlying molecular mechanisms for PQ-mediated pathologic processes. Growing sets of data from in vitro and in vivo models have demonstrated the involvement of the PQ in regulating lung oxidative stress, inflammatory response, epigenetics, apoptosis, autophagy, and the progression of lung fibrosis. The article also summarizes novel therapeutic avenues based on a literature review, which can be explored as potential means to combat PQ-induced lung toxicity. Finally, we also presented clinical studies on the association of PQ exposure with the incidence of lung injury and pulmonary fibrosis.

4-PBA Enhances Autophagy by Inhibiting Endoplasmic Reticulum Stress in Recombinant Human Beta Nerve Growth Factor-Induced PC12 cells After Mechanical Injury via PI3K/AKT/mTOR Signaling Pathway

OBJECTIVE

To investigate mechanism of endoplasmic reticulum (ER) stress-mediated autophagy in spinal cord injury (SCI).

METHODS

An in vitro model of spinal cord injury (SCI) was established by recombinant human beta nerve growth factor (NGF)-induced PC12 cells. Immunofluorescence was used to detect properties of PC12 cells induced by NGF. Western blot assay was used to detect expressions of the autophagy-related protein microtubule-associated protein 1 light chain 3 (LC3)I/II, the ER stress-related protein (HSPA5/GRP78), as well as the PI3K/AKT/mTOR signaling pathway-related proteins after mechanical injury at different time points. Then the sample assigned into sham, SCI, LY294002, SCI+LY294002, 4-PBA (4-phenylbutyric acid), and SCI+4-PBA groups. The expressions of the LC3I/II and PI3K/AKT/mTOR signaling pathway-related proteins were detected by Western blot assay.

RESULTS

NGF-induced PC12 cells have neurophysiological characteristics. After administration of the PI3K-specific inhibitor LY294002, phosphorylation levels of AKT and mTOR decreased, and the ratio of LC3II/I was higher in the inhibitor-treated injury group than the simple-injury group. After administration of the ER stress inhibitor 4-PBA, the results were similar to LY294002 group's results compared with SCI group.

CONCLUSIONS

Our study showed that NGF-induced PC12 cells can induce autophagy and ER stress after mechanical injury. ER stress inhibitor 4-PBA obtained similar effects to PI3K inhibitor LY294002, enhanced autophagy via PI3K/AKT/mTOR signaling pathway.

The regulation of autophagy in the pesticide-induced toxicity: Angel or demon?

Pesticides have become an essential tool for pest kill, weed control and microbiome inhibition for both agricultural and domestic use. However, with the massive use, pesticides can exist in soil, air and water, and sometimes even accumulate in the human or other mammals through food chains. Lots of researches have proven that pesticides possess toxicity to mammals on endocrine, neural and immune systems. Autophagy, as a conservative intracellular process, which is activated by stress-related signals, plays a pivotal role, either "angle" or "demon", in regulation of cell fate and function. Recent evidences in researches elucidated a strong link between the autophagy and the toxicity of pesticides. In this review, we summarized the previous researches which focus on the autophagy regulation in the pesticides-induced toxicity, and hope that this work can help us to discover a potential strategy for the treatment of the disease caused by pesticides.

Paraquat Degradation From Contaminated Environments: Current Achievements and Perspectives

Paraquat herbicide has served over five decades to control annual and perennial weeds. Despite agricultural benefits, its toxicity to terrestrial and aquatic environments raises serious concerns. Paraquat cannot rapidly degrade in the environment and is adsorbed in clay lattices that require urgent environmental remediation. Advanced oxidation processes (AOPs) and bioaugmentation techniques have been developed for this purpose. Among various techniques, bioremediation is a cost-effective and eco-friendly approach for pesticide-polluted soils. Though several paraquat-degrading microorganisms have been isolated and characterized, studies about degradation pathways, related functional enzymes and genes are indispensable. This review encircles paraquat removal from contaminated environments through adsorption, photocatalyst degradation, AOPs and microbial degradation. To provide in-depth knowledge, the potential role of paraquat degrading microorganisms in contaminated environments is described as well.

Cellular uptake of paraquat determines subsequent toxicity including mitochondrial damage in lung epithelial cells

Paraquat (PQ) is one of the commonly used herbicides in the world, despite its high toxicity. The ingestion of PQ accidentally or intentionally causes severe damage in diverse organs including the lung. Pulmonary fibrosis triggered by PQ accumulation in the lung epithelial cells is one of the major causes of death. This study investigated the intracellular accumulation of PQ, reactive oxygen species (ROS) generation and mitochondrial injury using two lung epithelial cell lines A549 and BEAS-2B (BEAS). Although A549 exhibit greater resistance to oxidative stress than BEAS, a cytotoxicity assay for PQ demonstrated that EC₅₀ for lethality in A549 was 7 times lower than that in BEAS. When exposed to PQ at a concentration around EC₅₀ for lethality, the amount of ROS generated in A549 was as low as that in BEAS. Conversely, the cellular concentration of PQ in A549 after exposure was higher than that in BEAS, which suggests a distinct difference in the susceptibility to PQ between these cell lines. After a 16 h exposure to PQ, mitochondrial membrane potential (MMP) decreased in A549, but decreased only slightly in BEAS even following a 30 h exposure. PQ-exposed A549 reduced an accumulation of PTEN-induced kinase 1 (PINK1), which works in degradation of damaged mitochondria, following the decrease of MMP, whereas PQ did not decline the PINK1 in BEAS. These results suggest that mitochondrial dysfunction due to cellular accumulation of PQ might contribute to the PQ-provoked toxicity more than the ROS generation in the lung epithelial cells.