Mitochondrial malfunction-initiated Leydig cell premature senescence partially participates in 1-nitropyrene-evoked downregulation of steroidogenic synthases in testes.

Serum testosterone (T) in males has been declining during the past decades. The previous reports found that 1-nitropyrene (1-NP) exposure suppressed testicular T synthesis. The purpose of the current study was to further explore whether premature senescence participates in 1-NP-triggered reduction of testicular T synthesis. Adult male mice were orally exposed to 1-NP (0, 100, and 500 µg/kg) daily for 14 days. Serum and testicular T contents were diminished in 1-NP-administered mice. Mitochondria-located steroidogenic synthases, including StAR, CYP11A1, and 3ßHSD1, were downregulated in 1-NP-administered mouse testes and MLTC-1 cells. Mechanistically, 1-NP exposure increased acetylation modification of mitochondrial steroidogenic synthases by inhibiting the enzymatic activity of SIRT3, an NAD+-dependent deacetylase. Supplementing NAD + precursor and Sirt3 overexpression relieved 1-NP-triggered reduction of steroidogenic synthase levels in mouse testes and MLTC-1 cells. By contrast, Sirt3 silencing aggravated 1-NP-evoked acetylation and reduction of steroidogenic synthase levels in MLTC-1 cells. Further experiments demonstrated that 1-NP exposure caused mitochondrial malfunction and premature senescence in mouse testes and MLTC-1 cells. Supplementation with mitochondria-directed antioxidant mitoquinone (MitoQ) prevented 1-NP-evoked Leydig cell premature senescence and downregulation of testicular steroidogenic synthases. These results suggest that mitochondrial malfunction-initiated Leydig cell premature senescence may partially participate in 1-NP-evoked reduction of steroidogenic synthase levels in testes.

Short-term respiratory cadmium exposure partially activates pulmonary NLRP3 inflammasome by inducing ferroptosis in mice.

Cadmium (Cd) is a common environmental metal. Previous studies indicated that long-term respiratory Cd exposure caused lung injury and airway inflammation. The purpose of this study was to evaluate whether short-term respiratory Cd exposure induces pulmonary ferroptosis and NLRP3 inflammasome activation. Adult C57BL/6J mice were exposed to Cd by inhaling CdCl2 aerosol (0, 10, or 100 ppm) for 5 days. Serum and lung Fe2+ contents were elevated in Cd-exposed mice. Oxidized AA metabolites, the major oxidized lipids during ferroptosis, were upregulated in Cd-exposed mouse lungs. Pulmonary MDA content and 4-HNE-positive cells were increased in Cd-exposed mice. ACSL4 and COX-2, two lipoxygenases, were upregulated in Cd-exposed mouse lungs. Further analyses found that phosphorylated NF-kB p65 was elevated in Cd-exposed mouse lungs. Innate immune receptor protein NLRP3 and adapter protein ASC were upregulated in Cd-exposed mouse lungs. Caspase-1 was activated and IL-1ß and IL-18 were upregulated in Cd-exposed mouse lungs. Fer-1, a specific inhibitor of ferroptosis, attenuated Cd-induced elevation of pulmonary NLRP3 and ASC, caspase-1 activation, and IL-1ß and IL-18 upregulation. Finally, mitoquinone (MitoQ), a mitochondria-target antioxidant, suppressed Cd-caused ferroptosis and NLRP3 inflammasome activation. Our results demonstrate that ferroptosis might partially mediate Cd-evoked activation of NLRP3 inflammasome in the lungs.

Role of the GalNAc-galectin pathway in the healing of premature rupture of membranes.

BACKGROUND: Premature rupture of the membranes (PROM) is a key cause of preterm birth and represents a major cause of neonatal mortality and morbidity. Natural products N-acetyl-d-galactosamine (GalNAc), which are basic building blocks of important polysaccharides in biological cells or tissues, such as chitin, glycoproteins, and glycolipids, may improve possible effects of wound healing. METHODS: An in vitro inflammation and oxidative stress model was constructed using tumor necrosis-α (TNF-α) and lipopolysaccharide (LPS) action on WISH cells. Human amniotic epithelial cells (hAECs) were primarily cultured by digestion to construct a wound model. The effects of GalNAc on anti-inflammatory and anti-oxidative stress, migration and proliferation, epithelial-mesenchymal transition (EMT), glycosaminoglycan (GAG)/hyaluronic acid (HA) production, and protein kinase B (Akt) pathway in hAECs and WISH cells were analyzed using the DCFH-DA fluorescent probe, ELISA, CCK-8, scratch, transwell migration, and western blot to determine the mechanism by which GalNAc promotes amniotic wound healing. RESULTS: GalNAc decreased IL-6 expression in TNF-α-stimulated WISH cells and ROS expression in LPS-stimulated WISH cells (P < 0.05). GalNAc promoted the expression of Gal-1 and Gal-3 with anti-inflammatory and anti-oxidative stress effects. GalNAc promoted the migration of hAECs (50% vs. 80%) and WISH cells through the Akt signaling pathway, EMT reached the point of promoting fetal membrane healing, and GalNAc did not affect the activity of hAECs and WISH cells (P > 0.05). GalNAc upregulated the expression of sGAG in WISH cells (P < 0.05) but did not affect HA levels (P > 0.05). CONCLUSIONS: GalNAc might be a potential target for the prevention and treatment of PROM through the galectin pathway, including (i) inflammation; (ii) epithelial-mesenchymal transition; (iii) proliferation and migration; and (iv) regression, remodeling, and healing.

Gestational PFAS exposure and newborn size: The modifying effect of cord blood fatty acids.

Per- and polyfluoroalkyl substances (PFASs) can disrupt lipid metabolism, and changes in cord blood fatty acid composition have been observed in small newborns. Emerging evidence suggests that exposure to PFASs during pregnancy is linked to decreased newborn size, although the evidence is not consistent. The modifying effect of fatty acids on the associations of gestational PFAS exposure with newborn size is still unknown. Here we show that the nutritional status of the fetus, as indicated by the level of fatty acids in the cord blood, mitigates the adverse effects of gestational PFAS exposure on the size of the newborn. Our study confirms the adverse developmental effects of PFASs and identifies emerging short-chain PFASs as the primary drivers of reduced newborn size, despite their lower exposure burden compared to legacy PFASs. Additionally, we find the protective role of cord blood fatty acids, suggesting potential strategies for mitigating the detrimental effects of emerging environmental exposures on human health. Our findings provide new evidence of the potential toxicity of emerging PFASs and call for further toxicity evaluations of these pollutants for regulatory purposes. Future studies should consider the complex interaction between exposure and nutrition within the human body, particularly during the first thousand days of life, to promote lifelong health.

Mitochondrial Dysfunction-Evoked DHODH Acetylation is Involved in Renal Cell Ferroptosis during Cisplatin-Induced Acute Kidney Injury.

Several studies have observed renal cell ferroptosis during cisplatin-induced acute kidney injury (AKI). However, the mechanism is not completely clear. In this study, oxidized arachidonic acid (AA) metabolites are increased in cisplatin-treated HK-2 cells. Targeted metabolomics showed that the end product of pyrimidine biosynthesis is decreased and the initiating substrate of pyrimidine biosynthesis is increased in cisplatin-treated mouse kidneys. Mitochondrial DHODH, a key enzyme for pyrimidine synthesis, and its downstream product CoQH2, are downregulated. DHODH overexpression attenuated but DHODH silence exacerbated cisplatin-induced CoQH2 depletion and lipid peroxidation. Mechanistically, renal DHODH acetylation is elevated in cisplatin-exposed mice. Mitochondrial SIRT3 is reduced in cisplatin-treated mouse kidneys and HK-2 cells. Both in vitro SIRT3 overexpression and in vivo NMN supplementation attenuated cisplatin-induced mitochondrial DHODH acetylation and renal cell ferroptosis. By contrast, Sirt3 knockout aggravated cisplatin-induced mitochondrial DHODH acetylation and renal cell ferroptosis, which can not be attenuated by NMN. Additional experiments showed that cisplatin caused mitochondrial dysfunction and SIRT3 SUMOylation. Pretreatment with mitochondria-target antioxidant MitoQ alleviated cisplatin-caused mitochondrial dysfunction, SIRT3 SUMOylation, and DHODH acetylation. MitoQ pretreatment protected against cisplatin-caused AKI and renal cell ferroptosis. Taken together, these results suggest that mitochondrial dysfunction-evoked DHODH acetylation partially contributes to renal cell ferroptosis during cisplatin-induced AKI.

Plin4 exacerbates cadmium-decreased testosterone level via inducing ferroptosis in testicular Leydig cells.

Strong evidence indicates that environmental stressors are the risk factors for male testosterone deficiency (TD). However, the mechanisms of environmental stress-induced TD remain unclear. Based on our all-cause male reproductive cohort, we found that serum ferrous iron (Fe2⁺) levels were elevated in TD donors. Then, we explored the role and mechanism of ferroptosis in environmental stress-reduced testosterone levels through in vivo and in vitro models. Data demonstrated that ferroptosis and lipid droplet deposition were observed in environmental stress-exposed testicular Leydig cells. Pretreatment with ferrostatin-1 (Fer-1), a specific ferroptosis inhibitor, markedly mitigated environmental stress-reduced testosterone levels. Through screening of core genes involved in lipid droplets formation, it was found that environmental stress significantly increased the levels of perilipins 4 (PLIN4) protein and mRNA in testicular Leydig cells. Further experiments showed that Plin4 siRNA reversed environmental stress-induced lipid droplet deposition and ferroptosis in Leydig cells. Additionally, environmental stress increased the levels of METTL3, METTL14, and total RNA m6A in testicular Leydig cells. Mechanistically, S-adenosylhomocysteine, an inhibitor of METTL3 and METTL14 heterodimer activity, restored the abnormal levels of Plin4, Fe2⁺ and testosterone in environmental stress-treated Leydig cells. Collectively, these results suggest that Plin4 exacerbates environmental stress-decreased testosterone level via inducing ferroptosis in testicular Leydig cells.

Adolescent co-exposure to environmental cadmium and high-fat diet induces cognitive decline via Larp7 m6A-mediated SIRT6 inhibition.

The effects and underlying mechanisms of adolescent exposure to combined environmental hazards on cognitive function remain unclear. Here, using a combined exposure model, we found significant cognitive decline, hippocampal neuronal damage, and neuronal senescence in mice exposed to cadmium (Cd) and high-fat diet (HFD) during adolescence. Furthermore, we observed a significant downregulation of Sirtuin 6 (SIRT6) expression in the hippocampi of co-exposed mice. UBCS039, a specific SIRT6 activator, markedly reversed the above adverse effects. Further investigation revealed that co-exposure obviously reduced the levels of La ribonucleoprotein 7 (LARP7), disrupted the interaction between LARP7 and SIRT6, ultimately decreasing SIRT6 expression in mouse hippocampal neuronal cells. Overexpression of Larp7 reversed the combined exposure-induced SIRT6 decrease and senescence in mouse hippocampal neuronal cells. Additionally, the results showed notably elevated levels of Larp7 m6A and YTH domain family protein 2 (YTHDF2) in mouse hippocampal neuronal cells treated with the combined hazards. Ythdf2 short interfering RNA, RNA immunoprecipitation, and RNA stability assays further demonstrated that YTHDF2 mediated the degradation of Larp7 mRNA under combined exposure. Collectively, adolescent co-exposure to Cd and HFD causes hippocampal senescence and cognitive decline in mice by inhibiting LARP7-mediated SIRT6 expression in an m6A-dependent manner.

Mitochondrial dysfunction-associated alveolar epithelial senescence is involved in CdCl2-induced COPD-like lung injury.

An earlier study found that respiratory cadmium chloride (CdCl2) exposure caused COPD-like lung injury. This study aimed to explore whether mitochondrial dysfunction-mediated alveolar epithelial senescence is involved in CdCl2-induced COPD-like lung injury. Adult C57BL/6 mice were exposed to CdCl2 (10 mg/L) aerosol for six months. Beta-galactosidase-positive cells, p21 and p16 were increased in CdCl2-exposed mouse lungs. The in vitro experiments showed that γ-H2AX was elevated in CdCl2-exposed alveolar epithelial cells. The cGAS-STING pathway was activated in CdCl2-exposed alveolar epithelial cells and mouse lungs. Cxcl1, Cxcl9, Il-10, Il-1ß and Mmp2, several senescence-associated secretory phenotypes (SASP), were upregulated in CdCl2-exposed alveolar epithelial cells. Mechanistically, CdCl2 exposure caused SIRT3 reduction and mitochondrial dysfunction in mouse lungs and alveolar epithelial cells. The in vitro experiment found that Sirt3 overexpression attenuated CdCl2-induced alveolar epithelial senescence and SASP. The in vivo experiments showed that Sirt3 gene knockout exacerbated CdCl2-induced alveolar epithelial senescence, alveolar structure damage, airway inflammation and pulmonary function decline. NMN, an NAD+ precursor, attenuated CdCl2-induced alveolar epithelial senescence and SASP in mouse lungs. Moreover, NMN supplementation prevented CdCl2-induced COPD-like alveolar structure damage, epithelial-mesenchymal transition and pulmonary function decline. These results suggest that mitochondrial dysfunction-associated alveolar epithelial senescence is involved in CdCl2-induced COPD-like lung injury.

Machine learning predicts the serum PFOA and PFOS levels in pregnant women: Enhancement of fatty acid status on model performance.

Human exposure to per- and polyfluoroalkyl substances (PFASs) has received considerable attention, particularly in pregnant women because of their dramatic changes in physiological status and dietary patterns. Predicting internal PFAS exposure in pregnant women, based on external and relevant parameters, has not been investigated. Here, machine learning (ML) models were developed to predict the serum concentrations of PFOA and PFOS in a large population of 588 pregnant participants. Dietary exposure characteristics, demographic parameters, and in particular, serum fatty acid (FA) data were used for the model development. The fitting results showed that the inclusion of FAs as covariates significantly improved the performance of the ML models, with the random forest (RF) model having the best predictive performance for PFOA (R2 = 0.33, MAE = 1.51 ng/mL, and RMSE = 1.89 ng/mL) and PFOS (R2 = 0.12, MAE = 2.65 ng/mL, and RMSE = 3.37 ng/mL). The feature importance analysis revealed that serum FAs greatly affected PFOA concentration in the pregnant women, with saturated FAs being associated with decreased PFOA levels and unsaturated FAs with increased levels. Comparison with one-compartment pharmacokinetic model further demonstrated the advantage of the ML models in predicting PFAS exposure in pregnant women. Our models correlate for the first time blood chemical concentrations with human FA status using ML, introducing a novel perspective on predicting PFAS levels in pregnant women. This study provides valuable insights concerning internal exposure of PFASs generated from external exposure, and contributes to risk assessment and management in pregnant populations.

Exposure to 1-nitropyrene after weaning induces anxiety-like behavior partially by inhibiting steroid hormone synthesis in prefrontal cortex.

1-Nitropyrene (1-NP) is a neurodevelopmental toxicant. This study was to evaluate the impact of exposure to 1-NP after weaning on anxiety-like behavior. Five-week-old mice were administered with 1-NP (0.1 or 1 mg/kg) daily for 4 weeks. Anxiety-like behaviour was measured using elevated-plus maze (EPM) and open field test (OFT). In EPM test, time spending in open arm and times entering open arm were reduced in 1-NP-treated mice. In OFT test, time spent in the center region and times entering the center region were diminished in 1-NP-treated mice. Prefrontal dendritic length and number of dendrite branches were decreased in 1-NP-treated mice. Prefrontal PSD95, an excitatory postsynaptic membrane protein, and gephyrin, an inhibitory postsynaptic membrane protein, were downregulated in 1-NP-treated mice. Further analysis showed that peripheral steroid hormones, including serum testosterone (T) and estradiol (E2), testicular T, and ovarian E2, were decreased in 1-NP-treated mice. Interestingly, T and E2 were diminished in 1-NP-treated prefrontal cortex. Prefrontal T and E2 synthases were diminished in 1-NP-treated mice. Mechanistically, GCN2-eIF2α, a critical pathway that regulates ribosomal protein translation, was activated in 1-NP-treated prefrontal cortex. These results indicate that exposure to 1-NP after weaning induces anxiety-like behaviour partially by inhibiting steroid hormone synthesis in prefrontal cortex.

Mitochondrial GPX4 acetylation is involved in cadmium-induced renal cell ferroptosis.

Increasing evidences demonstrate that environmental stressors are important inducers of acute kidney injury (AKI). This study aimed to investigate the impact of exposure to Cd, an environmental stressor, on renal cell ferroptosis. Transcriptomics analyses showed that arachidonic acid (ARA) metabolic pathway was disrupted in Cd-exposed mouse kidneys. Targeted metabolomics showed that renal oxidized ARA metabolites were increased in Cd-exposed mice. Renal 4-HNE, MDA, and ACSL4, were upregulated in Cd-exposed mouse kidneys. Consistent with animal experiments, the in vitro experiments showed that mitochondrial oxidized lipids were elevated in Cd-exposed HK-2 cells. Ultrastructure showed mitochondrial membrane rupture in Cd-exposed mouse kidneys. Mitochondrial cristae were accordingly reduced in Cd-exposed mouse kidneys. Mitochondrial SIRT3, an NAD+-dependent deacetylase that regulates mitochondrial protein stability, was reduced in Cd-exposed mouse kidneys. Subsequently, mitochondrial GPX4 acetylation was elevated and mitochondrial GPX4 protein was reduced in Cd-exposed mouse kidneys. Interestingly, Cd-induced mitochondrial GPX4 acetylation and renal cell ferroptosis were exacerbated in Sirt3-/- mice. Conversely, Cd-induced mitochondrial oxidized lipids were attenuated in nicotinamide mononucleotide (NMN)-pretreated HK-2 cells. Moreover, Cd-evoked mitochondrial GPX4 acetylation and renal cell ferroptosis were alleviated in NMN-pretreated mouse kidneys. These results suggest that mitochondrial GPX4 acetylation, probably caused by SIRT3 downregulation, is involved in Cd-evoked renal cell ferroptosis.

Benzo[a]pyrene evokes epithelial-mesenchymal transition and pulmonary fibrosis through AhR-mediated Nrf2-p62 signaling.

Benzo[a]pyrene (BaP) and its metabolic end product benzo(a)pyren-7,8-dihydrodiol-9,10-epoxide (BPDE), are known toxic environmental pollutants. This study aimed to analyze whether sub-chronic BPDE exposure initiated pulmonary fibrosis and the potential mechanisms. In this work, male C57BL6/J mice were exposed to BPDE by dynamic inhalation exposure for 8 weeks. Our results indicated that sub-chronic BPDE exposure evoked pulmonary fibrosis and epithelial-mesenchymal transition (EMT) in mice. Both in vivo and in vitro, BPDE exposure promoted nuclear translocation of Snail. Further experiments indicated that nuclear factor erythroid 2-related factor 2 (Nrf2) and p62 were upregulated in BPDE-exposed alveolar epithelial cells. Moreover, Nrf2 siRNA transfection evidently attenuated BPDE-induced p62 upregulation. Besides, p62 shRNA inhibited BPDE-incurred Snail nuclear translocation and EMT. Mechanically, BPDE facilitated physical interaction between p62 and Snail in the nucleus, then repressed Snail protein degradation by p62-dependent autophagy-lysosome pathway, and finally upregulated transcriptional activity of Snail. Additionally, aryl hydrocarbon receptor (AhR) was activated in BPDE-treated alveolar epithelial cells. Dual-luciferase assay indicated activating AhR could bind to Nrf2 gene promoter. Moreover, pretreatment with CH223191 or α-naphthoflavone (α-NF), AhR antagonists, inhibited BPDE-activated Nrf2-p62 signaling, and alleviated BPDE-induced EMT and pulmonary fibrosis in mice. Taken together, AhR-mediated Nrf2-p62 signaling contributes to BaP-induced EMT and pulmonary fibrosis.

Prenatal exposure to fenvalerate causes depressive-like behavior in adulthood by inhibiting brain-derived 5-HT synthesis.

The developmental toxicity of fenvalerate, a representative pyrethroid insecticide, is well documented. The present study aimed to explore whether prenatal exposure to fenvalerate causes depression-like behavior in adulthood. Pregnant mice were orally administrated with either corn oil or fenvalerate (2 or 20 mg/kg) during pregnancy. Depressive-like behaviors were assessed by tail suspension test (TST), forced swim test (FST) and sucrose preference test (SPT). Immobility times in TST and FST were increased in offspring whose mothers were exposed to fenvalerate throughout pregnancy. By contrast, sugar preference index, as determined by SPT, was decreased in fenvalerate-exposed offspring. Prefrontal PSD95, a postsynaptic membrane marker, was downregulated in fenvalerate-exposed adulthood offspring. Fenvalerate-induced reduction of prefrontal PSD95 began at GD18 fetal period. Accordingly, prefrontal 5-HT, a neurotransmitter for synaptogenesis, was also reduced in fenvalerate-exposed GD18 fetuses. Tryptophan hydroxylase 2 (TPH2), a key enzyme for 5-HT synthesis, was downregulated in the midbrain of fenvalerate-exposed GD18 fetuses. Additional experiment showed that GRP78 and p-eIF2α, two endoplasmic reticulum stress-related proteins, were increased in the midbrain of fenvalerate-exposed fetal mice. The present results suggest that prenatal exposure to fenvalerate causes depressive-like behavior in adulthood, partially by inhibiting brain-derived 5-HT synthesis.

Prenatal 1-Nitropyrene Exposure Causes Autism-Like Behavior Partially by Altering DNA Hydroxymethylation in Developing Brain.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder, characterized by social communication disability and stereotypic behavior. This study aims to investigate the impact of prenatal exposure to 1-nitropyrene (1-NP), a key component of motor vehicle exhaust, on autism-like behaviors in a mouse model. Three-chamber test finds that prenatal 1-NP exposure causes autism-like behaviors during the weaning period. Patch clamp shows that inhibitory synaptic transmission is reduced in medial prefrontal cortex of 1-NP-exposed weaning pups. Immunofluorescence finds that prenatal 1-NP exposure reduces the number of prefrontal glutamate decarboxylase 67 (GAD67) positive interneurons in fetuses and weaning pups. Moreover, prenatal 1-NP exposure retards tangential migration of GAD67-positive interneurons and downregulates interneuron migration-related genes, such as Nrg1, Erbb4, and Sema3F, in fetal forebrain. Mechanistically, prenatal 1-NP exposure reduces hydroxymethylation of interneuron migration-related genes through inhibiting ten-eleven translocation (TET) activity in fetal forebrain. Supplement with alpha-ketoglutarate (α-KG), a cofactor of TET enzyme, reverses 1-NP-induced hypohydroxymethylation at specific sites of interneuron migration-related genes. Moreover, α-KG supplement alleviates 1-NP-induced migration retardation of interneurons in fetal forebrain. Finally, maternal α-KG supplement improves 1-NP-induced autism-like behaviors in weaning offspring. In conclusion, prenatal 1-NP exposure causes autism-like behavior partially by altering DNA hydroxymethylation of interneuron migration-related genes in developing brain.

m6A-methylated Lonp1 drives mitochondrial proteostasis stress to induce testicular pyroptosis upon environmental cadmium exposure.

Cadmium (Cd) is a widely distributed typical environmental pollutant and one of the most toxic heavy metals. It is well-known that environmental Cd causes testicular damage by inducing classic types of cell death such as cell apoptosis and necrosis. However, as a new type of cell death, the role and mechanism of pyroptosis in Cd-induced testicular injury remain unclear. In the current study, we used environmental Cd to generate a murine model with testicular injury and AIM2-dependent pyroptosis. Based on the model, we found that increased cytoplasmic mitochondrial DNA (mtDNA), activated mitochondrial proteostasis stress occurred in Cd-exposed testes. We used ethidium bromide to generate mtDNA-deficient testicular germ cells and further confirmed that increased cytoplasmic mtDNA promoted AIM2-dependent pyroptosis in Cd-exposed cells. Uracil-DNA glycosylase UNG1 overexpression indicated that environmental Cd blocked UNG-dependent repairment of damaged mtDNA to drive the process in which mtDNA releases to cytoplasm in the cells. Interestingly, we found that environmental Cd activated mitochondrial proteostasis stress by up-regulating protein expression of LONP1 in testes. Testicular specific LONP1-knockdown significantly reversed Cd-induced UNG1 protein degradation and AIM2-dependent pyroptosis in mouse testes. In addition, environmental Cd significantly enhanced the m6A modification of Lonp1 mRNA and its stability in testicular germ cells. Knockdown of IGF2BP1, a reader of m6A modification, reversed Cd-induced upregulation of LONP1 protein expression and pyroptosis activation in testicular germ cells. Collectively, environmental Cd induces m6A modification of Lonp1 mRNA to activate mitochondrial proteostasis stress, increase cytoplasmic mtDNA content, and trigger AIM2-dependent pyroptosis in mouse testes. These findings suggest that mitochondrial proteostasis stress is a potential target for the prevention of testicular injury.

Arsenic exposure causes decline in sperm motility accompanied by energy metabolism disorders in mouse testes.

Arsenic (As) is a notorious environmental toxicant widely present in various natural environments. As exposure has been correlated with the decline in sperm motility. Yet, the mechanism has not been fully elucidated. Adult male C57 mice were given 0, 1, or 15 mg/L NaAsO2 for 10 weeks. The mature seminiferous tubules and sperm count were decreased in As-exposed mice. Sperm motility and several sperm motility parameters, including average path velocity (VAP), straight-line velocity (VSL), curvilinear velocity (VCL), beat-cross frequency (BCF), linearity (LIN), straightness (STR), and amplitude of lateral head displacement (ALH), were declined in As-exposed mice. RNA sequencing and transcriptomics analyses revealed that differentially expressed genes (DEGs) were mainly enriched in metabolic pathways. Untargeted metabolomics analyses indicated that energy metabolism was disrupted in As-exposed mouse testes. Gene set enrichment analysis showed that glycolysis and oxidative phosphorylation were disturbed in As-exposed mouse testes. As-induced disruption of testicular glucose metabolism and oxidative phosphorylation was further validated by RT-PCR and Western blotting. In conclusion, As exposure causes decline in sperm motility accompanied by energy metabolism disorders in mouse testes.

MitoQ protects against carbon tetrachloride-induced hepatocyte ferroptosis and acute liver injury by suppressing mtROS-mediated ACSL4 upregulation.

Ferroptosis has been shown to be involved in carbon tetrachloride (CCl4)-induced acute liver injury (ALI). The mitochondrion-targeted antioxidant MitoQ can eliminate the production of mitochondrial reactive oxygen species (mtROS). This study investigated the role of MitoQ in CCl4-induced hepatocytic ferroptosis and ALI. MDA and 4HNE were elevated in CCl4-induced mice. In vitro, CCl4 exposure elevated the levels of oxidized lipids in HepG2 cells. Alterations in the mitochondrial ultrastructure of hepatocytes were observed in the livers of CCl4-evoked mice. Ferrostatin-1 (Fer-1) attenuated CCl4-induced hepatic lipid peroxidation, mitochondrial ultrastructure alterations and ALI. Mechanistically, acyl-CoA synthetase long-chain family member 4 (ACSL4) was upregulated in CCl4-exposed human hepatocytes and mouse livers. The ACSL4 inhibitor rosiglitazone alleviated CCl4-induced hepatic lipid peroxidation and ALI. ACSL4 knockdown inhibited oxidized lipids in CCl4-exposed human hepatocytes. Moreover, CCl4 exposure decreased the mitochondrial membrane potential and OXPHOS subunit levels and increased the mtROS level in HepG2 cells. Correspondingly, MitoQ pretreatment inhibited the upregulation of ACSL4 in CCl4-evoked mouse livers and HepG2 cells. MitoQ attenuated lipid peroxidation in vivo and in vitro after CCl4 exposure. Finally, MitoQ pretreatment alleviated CCl4-induced hepatocytic ferroptosis and ALI. These findings suggest that MitoQ protects against hepatocyte ferroptosis in CCl4-induced ALI via the mtROS-ACSL4 pathway.

Pubertal exposure to Microcystin-LR arrests spermatogonia proliferation by inducing DSB and inhibiting SIRT6 dependent DNA repair in vivo and in vitro.

The reproduction toxicity of pubertal exposure to Microcystin-LR (MC-LR) and the underlying mechanism needs to be further investigated. In the current study, pubertal male ICR mice were intraperitoneally injected with 2 µg/kg MC-LR for four weeks. Pubertal exposure to MC-LR decreased epididymal sperm concentration and blocked spermatogonia proliferation. In-vitro studies found MC-LR inhibited cell proliferation of GC-1 cells and arrested cell cycle in G2/M phase. Mechanistically, MC-LR exposure evoked excessive reactive oxygen species (ROS) and induced DNA double-strand break in GC-1 cells. Besides, MC-LR inhibited DNA repair by reducing PolyADP-ribosylation (PARylation) activity of PARP1. Further study found MC-LR caused proteasomal degradation of SIRT6, a monoADP-ribosylation enzyme which is essential for PARP1 PARylation activity, due to destruction of SIRT6-USP10 interaction. Additionally, MG132 pretreatment alleviated MC-LR-induced SIRT6 degradation and promoted DNA repair, leading to the restoration of cell proliferation inhibition. Correspondingly, N-Acetylcysteine (NAC) pre-treatment mitigated the disturbed SIRT6-USP10 interaction and SIRT6 degradation, causing recovered DNA repair and subsequently restoration of cell proliferation inhibition in MC-LR treated GC-1 cells. Together, pubertal exposure to MC-LR induced spermatogonia cell cycle arrest and sperm count reduction by oxidative DNA damage and simultaneous SIRT6-mediated DNA repair failing. This study reports the effect of pubertal exposure to MC-LR on spermatogenesis and complex mechanism how MC-LR induces spermatogonia cell proliferation inhibition.

ALKBH5 SUMOylation-mediated FBXW7 m6A modification regulates alveolar cells senescence during 1-nitropyrene-induced pulmonary fibrosis.

Our previous study revealed that 1-nitropyrene (1-NP) exposure evoked pulmonary fibrosis in mice. However, the exact mechanism remained elusive. We found that 1-NP induced telomere damage and cellular senescence in mice lungs, and two alveolar epithelial cells lines. 1-NP downregulated telomere repeat binding factor 2 (TRF2), and upregulated FBXW7. Mechanistically, 1-NP-caused TRF2 ubiquitination and proteasomal degradation depended on E3 ubiquitin ligase activity of FBXW7. Moreover, 1-NP upregulated FBXW7 m6A modification via an ALKBH5-YTHDF1-dependent manner. Further analysis suggested 1-NP promoted ALKBH5 SUMOylation and subsequent proteasomal degradation. Additionally, 1-NP evoked mitochondrial reactive oxygen species (mtROS) overproduction. Mito-TEMPO, a mitochondrial-targeted antioxidant, mitigated 1-NP-caused mtROS overproduction, ALKBH5 SUMOylation, FBXW7 m6A modification, TRF2 degradation, cellular senescence, and pulmonary fibrosis. Taken together, mtROS-initiated ALKBH5 SUMOylation and subsequent FBXW7 m6A modification is indispensable for TRF2 degradation and cellular senescence in alveolar epithelial cells during 1-NP-induced pulmonary fibrosis. Our study provides target intervention measures towards 1-NP-evoked pulmonary fibrosis.