RNA-Seq provides new insights on the relative mRNA abundance of antioxidant components during mouse liver development

Advancing toxicity studies of per- and poly-fluoroalkyl substances (pfass) through machine learning: Models, mechanisms, and future directions

Perfluorinated and perfluoroalkyl substances (PFASs), encompassing a vast array of isomeric chemicals, are recognized as typical emerging contaminants with direct or potential impacts on human health and the ecological environment. With the complex and elusive toxicological profiles of PFASs, machine learning (ML) has been increasingly employed in their toxicity studies due to its proficiency in prediction and data analytics. This integration is poised to become a predominant trend in environmental toxicology, propelled by the swift advancements in computational technology. This review diligently examines the literature to encapsulate the varied objectives of employing ML in the toxicity studies of PFASs: (1) Utilizing ML to establish Quantitative Structure-Activity Relationship (QSAR) models for PFASs with diverse toxicity endpoints, facilitating the targeted toxicity prediction of unidentified PFASs; (2) Investigating and substantiating the Adverse Outcome Pathway (AOP) through the synergy of ML and traditional toxicological methods, with this refining the toxicity assessment framework for PFASs; (3) Dissecting and elucidating the features of established ML models to advance Open Research into the toxicity of PFASs, with a primary focus on determinants and mechanisms. The discourse extends to an in-depth examination of ML studies, segregating findings based on their distinct application trajectories. Given that ML represents a nascent paradigm within PFASs research, this review delineates the collective challenges encountered in the ML-mediated study of PFAS toxicity and proffers strategic guidance for ensuing investigations.

Activation of Nrf2 at Critical Windows of Development Alters Tissue-Specific Protein S-Glutathionylation in the Zebrafish (Danio rerio) Embryo

Activation of Nrf2-the master regulator of antioxidative response-at different stages of embryonic development has been shown to result in changes in gene expression, but the tissue-specific and downstream effects of Nrf2 activation during development remain unclear. This work seeks to elucidate the tissue-specific Nrf2 cellular localization and the downstream changes in protein S-glutathionylation during critical windows of zebrafish (Danio rerio) development. Wild-type and mutant zebrafish embryos with a loss-of-function mutation in Nrf2a were treated with two canonical activators, sulforaphane (SFN; 40 µM) or tert-butylhydroquinone (tBHQ; 1 µM), for 6 h at either pharyngula, hatching, or the protruding-mouth stage. Nrf2a protein and S-glutathionylation were visualized in situ using immunohistochemistry. At the hatching stage, Nrf2a protein levels were decreased with SFN, but not tBHQ, exposure. Exposure to both activators, however, decreased downstream S-glutathionylation. Stage- and tissue-specific differences in Nrf2a protein and S-glutathionylation were identified in the pancreatic islet and liver. Protein S-glutathionylation in Nrf2a mutant fish was increased in the liver by both activators, but not the islets, indicating a tissue-specific and Nrf2a-dependent dysregulation. This work demonstrates that critical windows of exposure and Nrf2a activity may influence redox homeostasis and highlights the importance of considering tissue-specific outcomes and sensitivity in developmental redox biology.

Developmental impacts of Nrf2 activation by dimethyl fumarate (DMF) in the developing zebrafish (Danio rerio) embryo

Dimethyl fumarate (DMF) is pharmaceutical activator of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), which regulates of many cellular antioxidant response pathways, and has been used to treat inflammatory diseases such as multiple sclerosis. However, DMF has been shown to produce adverse effects on offspring in animal studies and as such is not recommended for use during pregnancy. The goal of this work is to better understand how these adverse effects are initiated and the role of DMF-induced Nrf2 activation during three critical windows of development in embryonic zebrafish (Danio rerio): pharyngula, hatching, and protruding-mouth stages. To evaluate Nrf2 activation, wildtype zebrafish, and mutant zebrafish (nrf2afh318/fh318) embryos with a loss of function mutation in Nrf2a, the co-ortholog to human Nrf2, were treated for 6 h with DMF (0-20 μM) beginning at the pharyngula, hatching, or protruding-mouth stage and assessed for survival and morphology. Nrf2a mutant fish had an increase in survival, however, morphology studies demonstrated Nrf2a mutant fish had more severe deformities occurring with exposures during the hatching stage. To verify Nrf2 cellular localization and downstream impacts on protein-S-glutathionylation in situ, a concentration below the LOAEL was chosen (7 μM) for immunohistochemistry and S-glutathionylation. Embryos were imaged via epifluorescence microscopy studies, the Nrf2a protein in the body tissue was decreased with DMF only when exposed at the hatching stage, while total protein S-glutathionylation was modulated by Nrf2a activity and DMF during the pharyngula and protruding-mouth stage. The pancreatic islet and liver were further analyzed via confocal microscopy. Pancreatic islets and liver also had tissue specific differences with Nrf2a protein expression and protein S-glutathionylation. This work demonstrates how critical windows of exposure and Nrf2a activity may influence toxicity of DMF and highlights tissue-specific changes in Nrf2a protein levels and S-glutathionylation in pancreatic islet and liver during embryonic development.

Demethylzeylasteral attenuates hepatic stellate cell activation and liver fibrosis by inhibiting AGAP2 mediated signaling

BACKGROUND

Liver fibrosis is a common cause of chronic liver disease. If left untreated, it can ultimately develop into liver cirrhosis or hepatocellular carcinoma. However, a direct antifibrotic therapy is currently unavailable. A re-examination of existing chemicals might be a potential strategy for finding more lead compounds against liver fibrosis. Demethylzeylasteral (T-96), a naturally occurring bioactive compound found in Tripterygium wilfordii Hook. f. (TwHf) possesses multiple pharmacological properties. However, its antifibrotic potential has not yet been fully evaluated.

PURPOSE

This study aimed to investigate the antifibrotic properties of T-96 and its underlying molecular mechanisms.

METHODS

The antifibrotic properties of T-96 were investigated in three types of hepatic stellate cells (HSCs) and in a CCl₄-induced liver fibrosis mouse model. The effect of T-96 on the proliferation, migration, and activation of HSCs was detected using CCK-8 and scratch/wound healing assays. Hepatic inflammation and fibrosis were evaluated by H&E, Masson's trichrome stain, and Sirius Red staining. The expression of inflammatory and fibrogenic genes was detected by quantitative real-time PCR (qRT-PCR) and western blotting. RNA sequencing (RNA-seq) was performed to explore the potential molecular mechanisms mediating the antifibrotic effect of T-96, which was verified by dual-luciferase reporter assay, qRT-PCR, western blotting, immunofluorescence, and immunoprecipitation analysis.

RESULTS

The T-96 treatment significantly suppressed the proliferation, migration, and activation of HSCs in vitro. The administration of T-96 attenuated hepatic injury, inflammation, and fibrosis progression in mice with CCl₄-induced liver fibrosis. In addition, the RNA-seq of fibrotic liver tissues and subsequent functional verification indicated that the key mechanisms of the antifibrotic effect of T-96 were mediated by suppressing the expression of AGAP2 (Arf GAP with GTPase-like domain, ankyrin repeat and PH domain 2), inhibiting the subsequent phosphorylation of focal adhesion kinase (FAK) and protein kinase B (AKT), and finally reducing the expression of fibrosis-related genes.

CONCLUSION

Our results provide the first insight that T-96 exerts potent antifibrotic effects both in vitro and in vivo by inhibiting the AGAP2 mediated FAK/AKT signaling axis, and that T-96 may serve as a potential therapeutic candidate for the treatment of liver fibrosis.

Dynamic Transcriptomic Profiling During Liver Development in Schizothorax Prenanti

Liver is an important organ for glucose and lipid metabolism, immunity, and detoxification in fish. However, the gene regulatory network of postnatal liver development still remains unknown in teleost fish. In this study, we performed transcriptome analysis on the liver of S. prenanti at three stages. A total of 1692 differentially expressed genes (DGEs) were identified across three liver developmental stages. The oil red O staining and PAS staining revealed that the lipid content of liver was increased and the glycogen content of liver was decreased during liver development. The fatty acids biosynthesis related genes were upregulated in adult and young stages compared with juvenile stage, while lipid degradation related genes were downregulated. The genes related to glycolysis, gluconeogenesis and glycogenolysis were upregulated in juvenile or young stages compared with adult stage. Further pathway analysis indicated that the CYP450 pathway, cell cycle and amino acid metabolic pathway were induced in the process of liver maturation. Our study presents the gene expression pattern in different liver development stages of S. prenanti and may guide future studies on metabolism of S. prenanti liver.

Efficacy of Kushen decoction on high-fat-diet-induced hyperlipidemia in rats

OBJECTIVE

To investigate the efficacy and underlying mechanisms of action of Kushen decoction on high-fat-diet-induced hyperlipidemia in rats using RNA-seq technology.

METHODS

The efficacy of a Kushen decoction, at a concentration of 1 mL/g of crude medicine prepared according to the method commonly used in clinical practice, was investigated on 24 specific pathogen-free male Sprague-Dawley rats. Liver tissues were compared using RNA-Seq technology. The differentially expressed genes were further investigated by real-time fluorescent quantitative polymerase chain reaction (qPCR and Western blot (WB).

RESULTS

Serum triglycerides (TG), liver low-density lipoprotein cholesterol (LDL-C), body weight, body length, and Lee's index were significantly increased in the untreated hyperlipidemia-induced group (model) compared with the control group, whereas liver high-density lipoprotein cholesterol (HDL-C) was significantly decreased. Serum TG, liver LDL-C, bodyweight, and Lee's index were decreased in the high-dose Kushen decoction group (HDKS) compared with the model group, whereas liver HDL-C was significantly increased. Similarly, liver TG tended to decline in the HDKS group. Comparison of the gene expression profiles in the livers from different groups indicated that the Kushen decoction significantly affected metabolic pathways, PPAR signalling pathway, and circadian rhythm ( ≤ 0.05), with the genes ARNTL, PER3, and CLOCK being differentially expressed. qPCR and WB analysis confirmed the differential expression of the genes discovered by transcriptomics analysis.

CONCLUSION

The Kushen decoction may achieve a lipid-lowering effect on hyperlipidemic rats by regulating metabolic pathways and the circadian rhythm pathway and in particular, their related genes ARNTL, PER3, and CLOCK.

Age-related changes in liver metabolism and antioxidant capacity of laying hens

This study aimed to investigate the age-related changes of hepatic metabolism and antioxidant capacity of laying hens at 3 different ages. A total of 192 Hy-line Brown laying hens were assigned into 3 groups: 1) 195-day-old (D195 group); 2) 340-day-old (D340 group); 3) 525-day-old (D525 group). Each group replicated 8 times with 8 hens at the same age. Higher activity of aspartate aminotransferase and lower contents of total protein and globulin were observed in the serum of 525-day-old hens in comparison with their 195-day-old counterparts (P < 0.05). The 525-day-old hens accumulated higher contents of total cholesterol and triglyceride in the liver than 195-day-old birds. Additionally, compared with hens from D195 or D340 group, 525-day-old birds exhibited a lower circulating estradiol level (P < 0.05). For antioxidant capacity, birds in the D525 group showed a higher malondialdehyde concentration in both serum and liver as compared with D195 or D340 group (P < 0.05). The 525-day-old hens also exhibited lower glutathione peroxidase activities in both serum and liver when compared with 195-day-old birds (P < 0.05). Simultaneously, there was a decline of hepatic superoxide dismutase activity in the D525 group in comparison with D195 group (P < 0.05). Compared with 195-day-old counterparts, 340-day-old birds upregulated the mRNA abundance of nuclear factor erythroid-2 related factor 2 and glutathione peroxidase 1 in the liver (P < 0.05). In contrast, hens from D525 group showed the downregulation of hepatic nuclear factor erythroid-2 related factor 2, NAD(P)H quinone dehydrogenase 1, and superoxide dismutase 1 when compared with D340 group (P < 0.05). These results indicated that increasing age can adversely affect liver metabolism and function of laying hens.

Comparative evaluation of full-length isoform quantification from RNA-Seq

Background

Full-length isoform quantification from RNA-Seq is a key goal in transcriptomics analyses and has been an area of active development since the beginning. The fundamental difficulty stems from the fact that RNA transcripts are long, while RNA-Seq reads are short.

Results

Here we use simulated benchmarking data that reflects many properties of real data, including polymorphisms, intron signal and non-uniform coverage, allowing for systematic comparative analyses of isoform quantification accuracy and its impact on differential expression analysis. Genome, transcriptome and pseudo alignment-based methods are included; and a simple approach is included as a baseline control.

Conclusions

Salmon, kallisto, RSEM, and Cufflinks exhibit the highest accuracy on idealized data, while on more realistic data they do not perform dramatically better than the simple approach. We determine the structural parameters with the greatest impact on quantification accuracy to be length and sequence compression complexity and not so much the number of isoforms. The effect of incomplete annotation on performance is also investigated. Overall, the tested methods show sufficient divergence from the truth to suggest that full-length isoform quantification and isoform level DE should still be employed selectively.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12859-021-04198-1.

Sex-, Age-, and Race/Ethnicity-Dependent Variations in Drug-Processing and NRF2-Regulated Genes in Human Livers

Individual variations in xenobiotic metabolism affect the sensitivity to diseases. In this study, the impacts of sex, age, and race/ethnicity on drug-processing genes and nuclear factor erythroid 2-related factor 2 (NRF2) genes in human livers were examined via QuantiGene multiplex suspension array (226 samples) and quantitative polymerase chain reaction (qPCR) (247 samples) to profile the expression of nuclear receptors, cytochrome P450s, conjugation enzymes, transporters, bile acid metabolism, and NRF2-regulated genes. Sex differences were found in expression of about half of the genes, but in general the differences were not large. For example, females had higher transcript levels of catalase, glutamate-cysteine ligase catalytic subunit (GCLC), heme oxygenase 1 (HO-1), Kelch-like ECH-associated protein 1 (KEAP1), superoxide dismutase 1, and thioredoxin reductase-1 compared with males via qPCR. There were no apparent differences due to age, except children had higher glutamate-cysteine ligase modifier subunit (GCLM) and elderly had higher multidrug resistance protein 3. African Americans had lower expression of farnesoid X receptor (FXR) but higher expression of HO-1, Caucasians had higher expression of organic anion transporter 2, and Hispanics had higher expression of FXR, SULT2A1, small heterodimer partner, and bile salt export pump. An examination of 34 diseased and control human liver samples showed that compared with disease-free livers, fibrotic livers had higher NAD(P)H-quinone oxidoreductase 1 (NQO1), GCLC, GCLM, and NRF2; hepatocellular carcinoma had higher transcript levels of NQO1 and KEAP1; and steatotic livers had lower GCLC, GCLM, and HO-1 expression. In summary, in drug-processing gene and NRF2 genes, sex differences were the major findings, and there were no apparent age differences, and race/ethnicity differences occurred for a few genes. These descriptive findings could add to our understanding of the sex-, age-, and race/ethnicity-dependent differences in drug-processing genes as well as NRF2 genes in normal and diseased human livers. SIGNIFICANCE STATEMENT: In human liver drug-processing and nuclear factor erythroid 2-related factor 2 genes, sex differences were the main finding. There were no apparent differences due to age, except children had higher glutamate-cysteine ligase modifier subunit, and elderly had higher multidrug resistance protein 3. African Americans had lower expression of farnesoid X receptor (FXR) but higher expression of heme oxygenase 1, Caucasians had higher expression of organic anion transporter 2, and Hispanics had higher expression of FXR, small heterodimer partner, SULT2A1, and bile salt export pump.

Exposure to 2,3,3',4,4',5-hexachlorobiphenyl promotes nonalcoholic fatty liver disease development in C57BL/6 mice

Previous in vitro studies have indicated that 2,3,3',4,4',5-hexachlorobiphenyl (PCB 156) may be a new contributor to metabolic disruption and may further cause the occurrence of nonalcoholic fatty liver disease (NAFLD). However, no study has clarified the specific contributions of PCB 156 to NAFLD progression by constructing an in vivo model. Herein, we evaluated the effects of PCB 156 treatment (55 mg/kg, i.p.) on the livers of C57BL/6 mice fed a control diet (CD) or a high-fat diet (HFD). The results showed that PCB 156 administration increased intra-abdominal fat mass, hepatic lipid levels and dyslipidemia in the CD-fed group and aggravated NAFLD in HFD-fed group. By using transcriptomics studies and biological methods, we found that the genes expression involved in lipid metabolism pathways, such as lipogenesis, lipid accumulation and lipid β-oxidation, was greatly altered in liver tissues exposed to PCB 156. In addition, the cytochrome P450 pathway, peroxisome proliferator-activated receptors (PPARs) and the glutathione metabolism pathway were significantly activated following exposure to PCB 156. Furthermore, PCB 156 exposure increased serum transaminase levels and lipid peroxidation, and the redox-related genes were significantly dysregulated in liver tissue. In conclusion, our data suggested that PCB 156 could promote NAFLD development by altering the expression of genes related to lipid metabolism and inducing oxidative stress.

Lactobacillus fermentum JX306 Restrain D-galactose-induced Oxidative Stress of Mice through its Antioxidant Activity

Oxidative stress-induced series of related degenerative diseases have received widespread attention. To screen new lactic acid bacteria (LAB) strains to resist oxidative stress, traditional Chinese fermented vegetables were used as a resource library to screen of LAB. The Lactobacillus fermentum JX306 strain, which showed high scavenging activity of DPPH free radical and hydrogen radical, and a strong lipid peroxidation inhibition rate in vitro was selected. L. fermentum JX306 was also examined for its antioxidant capacity in D-galactose-induced aging mice. The results showed that L. fermentum JX306 could significantly decrease malondialdehyde (MDA) levels and improve the activity of glutathione peroxidase (GSH-Px), and total antioxygenic capacity (TOC) in the serum, kidney, and liver. Meanwhile, the strain could remarkably upregulate the transcriptional level of the antioxidant-related enzyme genes, such as peroxiredoxin1 (Prdx1), glutathione reductase (Gsr), glutathione peroxidase (Gpx1), and thioredoxin reductase (TR3) encoding genes in the liver. Besides, histopathological observation proves that this probiotic strain could effectively inhibit oxidative damage to the liver and kidney in aging mice. Therefore, this unique antioxidant strain may have a high application value in the functional food industry and medicine industry.