Copper Accumulation In Cells Research Articles

The copper P-type ATPase CtpA is involved in the response of Mycobacterium tuberculosis to redox stress

The functional difference among the three copper-transporting P-type ATPases (CtpA, CtpB, and CtpV) annotated in genome of Mycobacterium tuberculosis (Mtb) remains unclear. Thus, CtpA and CtpB are believed to deliver copper to extracytoplasmic proteins as a cofactor required to overcome redox and copper stress in the Mtb periplasm. This study investigates an alternative role of CtpA-mediated copper transportation and its possible interaction with the activity of the multicopper oxidase, (MmcO), in response to redox stress. Results from RT-qPCR experiments indicate that the ctpA gene is upregulated in low Cu2+ concentrations, and under oxidative (H2O2) and nitrosative (sodium nitroprusside) conditions in vitro, but not in high doses of Cu2+. Furthermore, the ctpA mutant strain (MtbΔctpA) showed impaired growth in the presence of oxidative and nitrosative stress in vitro. However, it did not display such growth impairments in response to high doses of copper in comparison to the wild-type strain. Disruption of the ctpA gene in the Mtb genome did not induce an accumulation of copper in cells under toxic doses of the metal, suggesting that CtpA is not directly involved in copper detoxification. On the other hand, whole-cell lysates of the MtbΔctpA mutant that were previously stimulated with Cu2+, H2O2 and SNP (sodium nitroprusside), displayed reduced ability to oxidize organic substrates (para-phenylenediamine (pPD) and 2,2-azino-bis (3-ethylbenzothiazo-line-6-sulfonic acid) (ABTS). These finding strongly suggest that the efflux of copper transported by CtpA from the cytoplasm is relevant to the response to the redox stress and may be required for metalation and activity of MmcO in Mtb.

Effects of Zearalenone on Apoptosis and Copper Accumulation of Goat Granulosa Cells In Vitro.

Zearalenone (ZEA), also known as F-2 toxin, is a mycotoxin. Despite numerous reports of ZEA impairing livestock production performance and fertility, little information is available, including information about the mechanism underlying damage to cell metal ion transport. Copper, which is essential for cell survival as a metal ion, can consist of a variety of enzymes that facilitate abundant metabolic processes. However, the accumulation of copper in cells can have toxic effects. Here, we intended to determine whether ZEA could impair goat granulosa cells (GCs) and alter the cellular copper concentration. GCs were divided into a negative control (NC) group (cells cultured with 0.1% dimethyl sulfoxide (DMSO) for 8 h) and a ZEA group (cells cultured with 200 μmol/L ZEA diluted in DMSO for 8 h). The results showed that ZEA could inhibit GC proliferation and impair cell viability. GCs showed significant increases in the apoptosis rate and oxidative stress levels, while their ability to synthesize estrogen decreased. In addition, RNA-seq results showed dramatic changes in the expression of copper transport-related genes. The expression levels of ATPase copper transporting alpha (ATP7A) and ATPase copper transporting beta (ATP7B) were significantly downregulated (p < 0.01), while the expression of solute carrier family 31 member 1 (SLC31A1) was not modified in the ZEA group compared with the NC group. In accordance with these trends, the copper concentration increased significantly in the ZEA group (p < 0.01). In summary, our results show that ZEA can negatively affect GCs and cause copper accumulation. This finding may provide a prospective line of research on the relationship between ZEA and the transport of copper ions in GCs.

Prognostic Significance of Cuproptosis-Related Gene Signatures in Breast Cancer Based on Transcriptomic Data Analysis

Breast cancer (BRCA) remains a serious threat to women's health, with the rapidly increasing morbidity and mortality being possibly due to a lack of a sophisticated classification system. To date, no reliable biomarker is available to predict prognosis. Cuproptosis has been recently identified as a new form of programmed cell death, characterized by the accumulation of copper in cells. However, little is known about the role of cuproptosis in breast cancer. In this study, a cuproptosis-related genes (CRGs) risk model was constructed, based on transcriptomic data with corresponding clinical information relating to breast cancer obtained from both the TCGA and GEO databases, to assess the prognosis of breast cancer by comprehensive bioinformatics analyses. The CRGs risk model was constructed and validated based on the expression of four genes (NLRP3, LIPT1, PDHA1 and DLST). BRCA patients were then divided into two subtypes according to the CRGs risk model. Furthermore, our analyses revealed that the application of this risk model was significantly associated with clinical outcome, immune infiltrates and tumor mutation burden (TMB) in breast cancer patients. Additionally, a new clinical nomogram model based on risk score was established and showed great performance in overall survival (OS) prediction, confirming the potential clinical significance of the CRGs risk model. Collectively, our findings revealed that the CRGs risk model can be a useful tool to stratify subtypes and that the cuproptosis-related signature plays an important role in predicting prognosis in BRCA patients.

Melatonin: A hypothesis regarding its use to treat Wilson disease

Wilson disease is associated with excessive copper accumulation in cells, primarily in the liver and brain. The subcellular lesions caused by an excess of this essential metal accounts for many of the signs of Wilson disease. The drugs used to treat this disease are not always effective, and depending on dose, they may have collateral toxicity. Melatonin is an endogenously-produced molecule that functions as a copper chelator, a potent antioxidant, and as a suppressor of endoplasmic reticulum stress and the unfolded protein response in both the liver and the brain, while also reducing fibrosis/cirrhosis in the liver. Melatonin is inexpensive, non-toxic and can be administered via any route. Melatonin should be tested for its potential utility in experimental models of Wilson disease with extension to the human if melatonin proves to be effective in the animal studies.

Copper accumulation in senescent cells: Interplay between copper transporters and impaired autophagy

Cellular senescence is characterized by irreversible growth arrest incurred through either replicative exhaustion or by pro-oncogenic cellular stressors (radioactivity, oxidative stress, oncogenic activation). The enrichment of senescent cells in tissues with age has been associated with tissue dyshomeostasis and age-related pathologies including cancers, neurodegenerative disorders (e.g. Alzheimer's, Parkinson's, etc.) and metabolic disorders (e.g. diabetes). We identified copper accumulation as being a universal feature of senescent cells [mouse embryonic fibroblasts (MEF), human prostate epithelial cells and human diploid fibroblasts] in vitro. Elevated copper in senescent MEFs was accompanied by elevated levels of high-affinity copper uptake protein 1 (Ctr1), diminished levels of copper-transporting ATPase 1 (Atp7a) (copper export) and enhanced antioxidant defence reflected by elevated levels of glutathione (GSH), superoxide dismutase 1 (SOD1) and glutaredoxin 1 (Grx1). The levels of intracellular copper were further increased in senescent MEFs cultured in copper supplemented medium and in senescent Mottled Brindled (Mobr) MEFs lacking functional Atp7a. Finally, we demonstrated that the restoration/preservation of autophagic-lysosomal degradation in senescent MEFs following rapamycin treatment correlated with attenuation of copper accumulation in these cells despite a further decrease in Atp7a levels. This study for the first time establishes a link between Atp7a and the autophagic-lysosomal pathway, and a requirement for both to effect efficient copper export. Such a connection between cellular autophagy and copper homeostasis is significant, as both have emerged as important facets of age-associated degenerative disease.

Role of p38MAPK and oxidative stress in copper-induced senescence

In the present work, we indicate that copper is involved in the senescence of human diploid fibroblasts and we describe mechanisms to explain it. Using different techniques, we show for the first time an accumulation of copper in cells during replicative senescence. This accumulation seems to be co-localized with lipofuscin. Second, we observed that an incubation of cells with copper sulfate induced oxidative stress, antioxidant response and premature senescence. Antioxidant molecules reduced the appearance of premature senescence. Third, we found that Nrf2 transcription factor was activated and regulated the expression of genes involved in antioxidant response while p38(MAPK) regulated the appearance of premature senescence.

Identification of sucrose-responsive microRNAs reveals sucrose-regulated copper accumulations in an SPL7-dependent and independent manner in Arabidopsis thaliana

Sucrose induces the expression of miR398 and the production of miR398 is controlled by SQUAMOSA promoter binding protein-like7 (SPL7) transcription factor under copper deficiency in Arabidopsis thaliana. Little else, however, is known about the sucrose-regulated copper homeostasis in Arabidopsis. Here, we employed the microarray technology to screen for sucrose-responsive microRNAs (miRNAs), and identified several candidates using northern blotting. In addition to miR398, miR408, miR319, and miR160 are also responsive to sucrose. Furthermore, the induction of miR398 and miR408 by sucrose depends on the presence of SPL7. MiR398 and miR408 induction by high sucrose was eliminated by high copper. Meanwhile, high sucrose treatment strongly suppressed copper accumulation. Knock-down of SPL7 dramatically reduced copper accumulation in plants under low sucrose, but this effect was compromised in the presence of high levels of sucrose. Taken together, these results suggest a connection between sucrose signaling and copper accumulation in cells, and that sucrose-regulated copper accumulation is both SPL7-dependent and SPL7-independent in Arabidopsis.