Effects of a Cumulative, Suboptimal Supply of Multiple Trace Elements in Mice: Trace Element Status, Genomic Stability, Inflammation, and Epigenetics

Long-term suboptimal dietary trace element supply does not affect trace element homeostasis in murine cerebellum

The ageing process is associated with alterations of systemic trace element (TE) homeostasis increasing the risk, e.g. neurodegenerative diseases. Here, the impact of long-term modulation of dietary intake of copper, iron, selenium, and zinc was investigated in murine cerebellum. Four- and 40-wk-old mice of both sexes were supplied with different amounts of those TEs for 26 wk. In an adequate supply group, TE concentrations were in accordance with recommendations for laboratory mice while suboptimally supplied animals received only limited amounts of copper, iron, selenium, and zinc. An additional age-adjusted group was fed selenium and zinc in amounts exceeding recommendations. Cerebellar TE concentrations were measured by inductively coupled plasma-tandem mass spectrometry. Furthermore, the expression of genes involved in TE transport, DNA damage response, and DNA repair as well as selected markers of genomic stability [8-oxoguanine, incision efficiency toward 8-oxoguanine, 5-hydroxyuracil, and apurinic/apyrimidinic sites and global DNA (hydroxy)methylation] were analysed. Ageing resulted in a mild increase of iron and copper concentrations in the cerebellum, which was most pronounced in the suboptimally supplied groups. Thus, TE changes in the cerebellum were predominantly driven by age and less by nutritional intervention. Interestingly, deviation from adequate TE supply resulted in higher manganese concentrations of female mice even though the manganese supply itself was not modulated. Parameters of genomic stability were neither affected by age, sex, nor diet. Overall, this study revealed that suboptimal dietary TE supply does not substantially affect TE homeostasis in the murine cerebellum.

Novel Molecular Subtyping Scheme Based on In Silico Analysis of Cuproptosis Regulator Gene Patterns Optimizes Survival Prediction and Treatment of Hepatocellular Carcinoma

BACKGROUND

The liver plays an important role in maintaining copper homeostasis. Copper ion accumulation was elevated in HCC tissue samples. Copper homeostasis is implicated in cancer cell proliferation and angiogenesis. The potential of copper homeostasis as a new theranostic biomarker for molecular imaging and the targeted therapy of HCC has been demonstrated. Recent studies have reported a novel copper-dependent nonapoptotic form of cell death called cuproptosis, strikingly different from other known forms of cell death. The correlation between cuproptosis and hepatocellular carcinoma (HCC) is not fully understood.

MATERIALS AND METHODS

The transcriptomic data of patients with HCC were retrieved from the Cancer Genome Atlas-Liver Hepatocellular Carcinoma (TCGA-LIHC) and were used as a discovery cohort to construct the prognosis model. The gene expression data of patients with HCC retrieved from the International Cancer Genome Consortium (ICGC) and Gene Expression Omnibus (GEO) databases were used as the validation cohort. The Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis was used to construct the prognosis model. A principal component analysis (PCA) was used to evaluate the overall characteristics of cuproptosis regulator genes and obtain the PC1 and PC2 scores. Unsupervised clustering was performed using the ConsensusClusterPlus R package to identify the molecular subtypes of HCC. Cox regression analysis was performed to identify cuproptosis regulator genes that could predict the prognosis of patients with HCC. The receiver operating characteristics curve and Kaplan-Meier survival analysis were used to understand the role of hub genes in predicting the diagnosis and prognosis of patients, as well as the prognosis risk model. A weighted gene co-expression network analysis (WGCNA) was used for screening the cuproptosis subtype-related hub genes. The functional enrichment analysis was performed using Metascape. The 'glmnet' R package was used to perform the LASSO regression analysis, and the randomForest algorithm was performed using the 'randomForest' R package. The 'pRRophetic' R package was used to estimate the anticancer drug sensitivity based on the data retrieved from the Genomics of Drug Sensitivity in Cancer database. The nomogram was constructed using the 'rms' R package. Pearson's correlation analysis was used to analyze the correlations.

RESULTS

We constructed a six-gene signature prognosis model and a nomogram to predict the prognosis of patients with HCC. The Kaplan-Meier survival analysis revealed that patients with a high-risk score, which was predicted by the six-gene signature model, had poor prognoses (log-rank test p < 0.001; HR = 1.83). The patients with HCC were grouped into three distinct cuproptosis subtypes (Cu-clusters A, B, and C) based on the expression pattern of cuproptosis regulator genes. The patients in Cu-cluster B had poor prognosis (log-rank test p < 0.001), high genomic instability, and were not sensitive to conventional chemotherapeutic treatment compared to the patients in the other subtypes. Cancer cells in Cu-cluster B exhibited a higher degree of the senescence-associated secretory phenotype (SASP), a marker of cellular senescence. Three representative genes, CDCA8, MCM6, and NCAPG2, were identified in patients in Cu-cluster B using WGCNA and the "randomForest" algorithm. A nomogram was constructed to screen patients in the Cu-cluster B subtype based on three genes: CDCA8, MCM6, and NCAPG2.

CONCLUSION

Publicly available databases and various bioinformatics tools were used to study the heterogeneity of cuproptosis in patients with HCC. Three HCC subtypes were identified, with differences in the survival outcomes, genomic instability, senescence environment, and response to anticancer drugs. Further, three cuproptosis-related genes were identified, which could be used to design personalized therapeutic strategies for HCC.

The Impact of Essential Trace Elements on Ovarian Response and Reproductive Outcomes following Single Euploid Embryo Transfer

Essential trace elements are required in extremely small amounts and obtained through diet. This research focuses on detecting major trace elements in different biofluids of sixty women undergoing ICSI with PGT-A and SET/FET at IVI-RMA, New Jersey, and assessing their impact on their IVF outcomes. Urine, plasma, and follicular fluid samples were collected on the vaginal oocyte retrieval day to measure the concentrations of eight essential trace elements (copper, zinc, molybdenum, lithium, selenium, manganese, chromium, and iron) using ICP-MS. After analysis, ovarian response and preimplantation outcomes had significant positive associations with both copper alone and the copper/zinc ratio in the follicular fluid and plasma, in addition to plasma manganese. Alternatively, elevated follicular fluid lithium concentrations were significantly associated with poor preimplantation outcomes while the urinary molybdenum concentration was significantly associated with a lower probability of implantation, clinical pregnancy, and live birth. Urinary lithium and chromium concentrations were significantly associated with a lower probability of achieving a live birth. Our results suggest that the essential trace elements present in follicular fluid, plasma, and urine of women are directly associated with their reproductive outcomes, with copper and manganese exerting positive effects and lithium and molybdenum exerting negative effects.

Effect of different iodine levels on the DNA methylation of PRKAA2, ITGA6, THEM4 and PRL genes in PI3K-AKT signaling pathway and population-based validation from autoimmune thyroiditis patients

PURPOSE

Autoimmune thyroiditis (AIT) is one of the most common autoimmune endocrine diseases. The currently recognized causes are genetic susceptibility, environmental factors and immune disorders. It is important to clarify the pathogenesis for the prevention, diagnosis, treatment of AIT and scientific iodine supplementation. This study analyzed the DNA methylation levels of PRKAA2, ITGA6, PRL and THEM4 genes related to PI3K-AKT signaling pathway, compared the DNA methylation levels between cases and controls from different water iodine levels in Shandong Province of China, and evaluated the contribution of PI3K-AKT signaling pathway-related genes in AIT.

METHODS

A total of 176 adult AIT patients were included from three different water iodine areas, and 176 healthy controls were included according to gender, age and BMI. According to the results of the Illumina Methylation 850 K BeadChip in our previous research, the significant methylation differences of genes on the PI3K-AKT signaling pathway related to AIT were determined. The MethylTarget™ assay was used to detect the methylation levels of the target genes, and real-time PCR experiments were used to verify the mRNA expression levels.

RESULTS

Compared with the control group, PRKAA2_3 and 15 CpG sites were hyper-methylated. ITGA6 gene and 2 CpG sites were hypo-methylated in AIT cases. The mRNA expression of ITGA6 gene was negatively correlated with the DNA methylation levels of ITGA6 gene and 2 CpG sites. Compared with cases and controls in areas with different water iodine levels, methylation differences were mainly in PRKAA2 and ITGA6 genes. The methylation levels of PRKAA2_1 and PRKAA2_3 were positively correlated with age. The methylation levels of PRL and THEM4 genes were negatively correlated with age. The methylation level of PRKAA2_3 was positively correlated with FT₄.

CONCLUSION

In summary, we identified aberrant DNA methylation levels of PRKAA2 and ITGA6 genes related to PI3K-AKT signaling pathway in the blood of AIT patients. Both iodine supplementation after long-term iodine deficiency and iodine excess can affect the DNA methylation levels of PRKAA2 and ITGA6 genes, and the former affects more obviously. In ITGA6 gene, this aberrant epigenetic modification is associated with the increased mRNA expression.

Effects of Manganese on Genomic Integrity in the Multicellular Model Organism Caenorhabditis elegans

Although manganese (Mn) is an essential trace element, overexposure is associated with Mn-induced toxicity and neurological dysfunction. Even though Mn-induced oxidative stress is discussed extensively, neither the underlying mechanisms of the potential consequences of Mn-induced oxidative stress on DNA damage and DNA repair, nor the possibly resulting toxicity are characterized yet. In this study, we use the model organism Caenorhabditis elegans to investigate the mode of action of Mn toxicity, focusing on genomic integrity by means of DNA damage and DNA damage response. Experiments were conducted to analyze Mn bioavailability, lethality, and induction of DNA damage. Different deletion mutant strains were then used to investigate the role of base excision repair (BER) and dePARylation (DNA damage response) proteins in Mn-induced toxicity. The results indicate a dose- and time-dependent uptake of Mn, resulting in increased lethality. Excessive exposure to Mn decreases genomic integrity and activates BER. Altogether, this study characterizes the consequences of Mn exposure on genomic integrity and therefore broadens the molecular understanding of pathways underlying Mn-induced toxicity. Additionally, studying the basal poly(ADP-ribosylation) (PARylation) of worms lacking poly(ADP-ribose) glycohydrolase (PARG) parg-1 or parg-2 (two orthologue of PARG), indicates that parg-1 accounts for most of the glycohydrolase activity in worms.

Ageing-associated effects of a long-term dietary modulation of four trace elements in mice

Trace elements (TEs) are essential for diverse processes maintaining body function and health status. The complex regulation of the TE homeostasis depends among others on age, sex, and nutritional status. If the TE homeostasis is disturbed, negative health consequences can result, e.g., caused by impaired redox homeostasis and genome stability maintenance. Based on age-related shifts in TEs which have been described in mice well-supplied with TEs, we aimed to understand effects of a long-term feeding with adequate or suboptimal amounts of four TEs in parallel. As an additional intervention, we studied mice which received an age-adapted diet with higher concentrations of selenium and zinc to counteract the age-related decline of both TEs. We conducted comprehensive analysis of diverse endpoints indicative for the TE and redox status, complemented by analysis of DNA (hydroxy)methylation and markers denoting genomic stability maintenance. TE concentrations showed age-specific alterations which were relatively stable and independent of their nutritional supply. In addition, hepatic DNA hydroxymethylation was significantly increased in the elderly mice and markers indicative for the redox status were modulated. The reduced nutritional supply with TEs inconsistently affected their status, with most severe effects regarding Fe deficiency. This may have contributed to the sex-specific differences observed in the alterations related to the redox status and DNA repair activity.

Overall, our results highlight the complexity of factors impacting on the TE status and its physiological consequences. Alterations in TE supply, age, and sex proved to be important determinants that need to be taken into account when considering TE interventions for improving general health and supporting convalescence in the clinics.

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Trace element profiles differ by age and sex under moderately modulated TE supply.

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Maintenance of age-related trace element shifts through all feeding groups.

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Cu/Zn ratio and DNA hydroxymethylation emerge as appropriate murine ageing markers.

N-Acetylcysteine as Modulator of the Essential Trace Elements Copper and Zinc

N-acetylcysteine (NAC) is a frequently prescribed drug and known for its metal chelating capability. However, to date it is not well characterized whether NAC intake affects the homeostasis of essential trace elements. As a precursor of glutathione (GSH), NAC also has the potential to modulate the cellular redox homeostasis. Thus, we aimed to analyze effects of acute and chronic NAC treatment on the homeostasis of copper (Cu) and zinc (Zn) and on the activity of the redox-sensitive transcription factor Nrf2. Cells were exposed to 1 mM NAC and were co-treated with 50 μM Cu or Zn. We showed that NAC treatment reduced the cellular concentration of Zn and Cu. In addition, NAC inhibited the Zn-induced Nrf2 activation and limited the concomitant upregulation of cellular GSH concentrations. In contrast, mice chronically received NAC via drinking water (1 g NAC/100 mL). Cu and Zn concentrations were decreased in liver and spleen. In the duodenum, NQO1, TXNRD, and SOD activities were upregulated by NAC. All of them can be induced by Nrf2, thus indicating a putative Nrf2 activation. Overall, NAC modulates the homeostasis of Cu and Zn both in vitro and in vivo and accordingly affects the cellular redox balance.