Publisher Correction: Therapeutic potential of N-acetylcysteine in acrylamide acute neurotoxicity in adult zebrafish

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Multiomic Analysis of Zebrafish Models of Acute Organophosphorus Poisoning With Different Severity

Organophosphorus compounds are acetylcholinesterase inhibitors used as pesticides and chemical warfare nerve agents. Acute organophosphorus poisoning (acute OPP) affects 3 million people, with 300 000 deaths annually worldwide. Severe acute OPP effects include overstimulation of cholinergic neurons, seizures, status epilepticus, and finally, brain damage. In a previous study, we developed 3 different chemical models of acute OPP in zebrafish larvae. To elucidate the complex pathophysiological pathways related to acute OPP, we used integrative omics (proteomic, transcriptomics, and metabolomics) on these 3 animal models. Our results show that these stochastic, apparently disparate morphological phenotypes can result from almost linear concentration-response variations in molecular levels. Results from the multiomics analysis strongly suggest that endoplasmic reticulum stress might play a central role in the pathophysiology of severe acute OPP, emphasizing the urgent need of further research on this molecular pathway. Endoplasmic reticulum stress could be an important therapeutic target to be included in the treatment of patients with severe acute OPP.

Modelling acrylamide acute neurotoxicity in zebrafish larvae

Acrylamide (ACR), a type-2 alkene, may lead to a synaptopathy characterized by ataxia, skeletal muscles weakness and numbness of the extremities in exposed human and laboratory animals. Currently, only the mildly affected patients undergo complete recovery, and identification of new molecules with therapeutic bioactivity against ACR acute neurotoxicity is urgently needed. Here, we have generated a zebrafish model for ACR neurotoxicity by exposing 5 days post-fertilization zebrafish larvae to 1 mM ACR for 3 days. Our results show that zebrafish mimics most of the pathophysiological processes described in humans and mammalian models. Motor function was altered, and specific effects were found on the presynaptic nerve terminals at the neuromuscular junction level, but not on the axonal tracts or myelin sheath integrity. Transcriptional markers of proteins involved in synaptic vesicle cycle were selectively altered, and the proteomic analysis showed that ACR-adducts were formed on cysteine residues of some synaptic proteins. Finally, analysis of neurotransmitters profile showed a significant effect on cholinergic and dopaminergic systems. These data support the suitability of the developed zebrafish model for screening of molecules with therapeutic value against this toxic neuropathy.

Nitrosothiol-Trapping-Based Proteomic Analysis of S-Nitrosylation in Human Lung Carcinoma Cells

Nitrosylation of cysteines residues (S-nitrosylation) mediates many of the cellular effects of nitric oxide in normal and diseased cells. Recent research indicates that S-nitrosylation of certain proteins could play a role in tumor progression and responsiveness to therapy. However, the protein targets of S-nitrosylation in cancer cells remain largely unidentified. In this study, we used our recently developed nitrosothiol trapping approach to explore the nitrosoproteome of human A549 lung carcinoma cells treated with S-nitrosocysteine or pro-inflammatory cytokines. Using this approach, we identified about 300 putative nitrosylation targets in S-nitrosocysteine-treated A549 cells and approximately 400 targets in cytokine-stimulated cells. Among the more than 500 proteins identified in the two screens, the majority represent novel targets of S-nitrosylation, as revealed by comparison with publicly available nitrosoproteomic data. By coupling the trapping procedure with differential thiol labeling, we identified nearly 300 potential nitrosylation sites in about 150 proteins. The proteomic results were validated for several proteins by an independent approach. Bioinformatic analysis highlighted important cellular pathways that are targeted by S-nitrosylation, notably, cell cycle and inflammatory signaling. Taken together, our results identify new molecular targets of nitric oxide in lung cancer cells and suggest that S-nitrosylation may regulate signaling pathways that are critically involved in lung cancer progression.

A substrate trapping approach identifies proteins regulated by reversible S-nitrosylation

Protein S-nitrosylation, the nitric oxide-mediated posttranslational modification of cysteine residues, has emerged as an important regulatory mechanism in diverse cellular processes. Yet, knowledge about the S-nitrosoproteome in different cell types and cellular contexts is still limited and many questions remain regarding the precise roles of protein S-nitrosylation and denitrosylation. Here we present a novel strategy to identify reversibly nitrosylated proteins. Our approach is based on nitrosothiol capture and enrichment using a thioredoxin trap mutant, followed by protein identification by mass spectrometry. Employing this approach, we identified more than 400 putative nitroso-proteins in S-nitrosocysteine-treated human monocytes and about 200 nitrosylation substrates in endotoxin and cytokine-stimulated mouse macrophages. The large majority of these represent novel nitrosylation targets and they include many proteins with key functions in cellular homeostasis and signaling. Biochemical and functional experiments in vitro and in cells validated the proteomic results and further suggested a role for thioredoxin in the denitrosylation and activation of inducible nitric oxide synthase and the protein kinase MEK1. Our findings contribute to a better understanding of the macrophage S-nitrosoproteome and the role of thioredoxin-mediated denitrosylation in nitric oxide signaling. The approach described here may prove generally useful for the identification and exploration of nitroso-proteomes under various physiological and pathophysiological conditions.

Dietary transforming growth factor-beta 2 (TGF-β2) supplementation reduces methotrexate-induced intestinal mucosal injury in a rat

BACKGROUND/AIMS

Dietary supplementation with transforming growth factor-beta (TGF-β) has been proven to minimize intestinal damage and facilitate regeneration after mucosal injury. In the present study, we evaluated the effects of oral TGF-β2 supplementation on intestinal structural changes, enterocyte proliferation and apoptosis following methotrexate (MTX)-induced intestinal damage in a rat and in a cell culture model.

METHODS

Caco-2 cells were treated with MTX and were incubated with increasing concentrations of TGF-β2. Cell apoptosis was assessed using FACS analysis by annexin staining and cell viability was monitored using Trypan Blue assay. Male rats were divided into four experimental groups: Control rats, CONTR- TGF-β rats were treated with diet enriched with TGF-β2, MTX rats were treated with a single dose of methotrexate, and MTX- TGF-β rats were treated with diet enriched with TGF-β2. Intestinal mucosal damage, mucosal structural changes, enterocyte proliferation and enterocyte apoptosis were determined at sacrifice. Real Time PCR and Western blot were used to determine bax and bcl-2 mRNA, p-ERK, β-catenin, IL-1B and bax protein expression.

RESULTS

Treatment of MTX-pretreated Caco-2 cells with TGF-B2 resulted in increased cell viability and decreased cell apoptosis. Treatment of MTX-rats with TGF-β2 resulted in a significant increase in bowel and mucosal weight, DNA and protein content, villus-height (ileum), crypt-depth (jejunum), decreased intestinal-injury score, decreased level of apoptosis and increased cell proliferation in jejunum and ileum compared to the untreated MTX group. MTX-TGF-β2 rats demonstrated a lower bax mRNA and protein levels as well as increased bcl-2 mRNA levels in jejunum and ileum compared to MTX group. Treatment with TGF-β2 also led to increased pERK, IL-1B and β-catenin protein levels in intestinal mucosa.

CONCLUSIONS

Treatment with TGF-β2 prevents mucosal-injury, enhances p-ERK and β-catenin induced enterocyte proliferation, inhibits enterocyte apoptosis and improves intestinal recovery following MTX-induced intestinal-mucositis in rats.