Chaperones CCS, ATOX and COXIV responses to copper supplementation in healthy adults

Mechanisms of chondrocyte cell death in osteoarthritis: implications for disease progression and treatment

Osteoarthritis (OA) is a chronic joint disease characterized by the degeneration, destruction, and excessive ossification of articular cartilage. The prevalence of OA is rising annually, concomitant with the aging global population and increasing rates of obesity. This condition imposes a substantial and escalating burden on individual health, healthcare systems, and broader social and economic frameworks. The etiology of OA is multifaceted and not fully understood. Current research suggests that the death of chondrocytes, encompassing mechanisms such as cellular apoptosis, pyroptosis, autophagy, ferroptosis and cuproptosis, contributes to both the initiation and progression of the disease. These cell death pathways not only diminish the population of chondrocytes but also exacerbate joint damage through the induction of inflammation and other deleterious processes. This paper delineates the morphological characteristics associated with various modes of cell death and summarizes current research results on the molecular mechanisms of different cell death patterns in OA. The objective is to review the advancements in understanding chondrocyte cell death in OA, thereby offering novel insights for potential clinical interventions.

Effects of Perioperative Zinc Supplementation on Copper Circulating Levels and Expression of Metallothionein and Copper Antioxidant Chaperone-1 in Leukocytes in Patients Undergoing CABG Surgery

The use of zinc supplement may have a negative effect on copper status. The objective of this study was to evaluate the effect of zinc and vitamin E supplementation on copper and zinc biomarkers in patients undergoing coronary artery bypass graft (CABG) surgery. The study was an add-on project to a previously published randomized controlled trial (NCT05402826) on patients undergoing CABG surgery. Patients in the zinc-vitamin E group (n = 40) received oral zinc (120 mg) and vitamin E (1200 international units) 1 day before surgery, followed by 30 mg of zinc and 200 units of vitamin E per day until 21 days after surgery, while those in the control group (n = 38) received placebo. Plasma levels of copper, ceruloplasmin, superoxide dismutase (SOD) activity, as well as leukocyte gene expression of metallothionein 2A (MT2A) and antioxidant protein 1 (ATOX1), were determined 3 and 21 days after surgery. The plasma copper level in the zinc-vitamin E group was significantly lower than the placebo group on the 3rd postoperative day, but no significant between-group differences were observed on day 21. Plasma ceruloplasmin concentration and SOD activity were not different. Relative mRNA expression of leukocyte MT2A was increased at both times (days 3 and 21 in the zinc-vitamin E group compared to placebo, but ATOX1 expression was not affected. Although the plasma copper level was transiently decreased early after surgery in the zinc-vitamin E group, considering the lack of change in other copper biomarkers, it seems that the use of zinc supplements at the dose used in the present study does not have a significant negative effect on the role of intracellular copper.

Highly Sensitive and Specific Responses of Oyster Hemocytes to Copper Exposure: Single-Cell Transcriptomic Analysis of Different Cell Populations

Oyster hemocytes are the primary vehicles transporting and detoxifying metals and are regarded as important cells for the occurrence of colored oysters due to copper (Cu) contamination. However, its heterogeneous responses under Cu exposure have not been studied. Single-cell transcriptome profiling (scRNA-seq) provides high-resolution visual insights into tissue dynamics and environmental responses. Here, we used scRNA-seq to study the responses of different cell populations of hemocytes under Cu exposure in an estuarine oyster Crassostrea hongkongensis. The 1900 population-specific Cu-responsive genes were identified in 12 clusters of hemocytes, which provided a more sensitive technique for examining Cu exposure. The granulocyte, semigranulocyte, and hyalinocyte had specific responses, while the granulocyte was the most important responsive cell type and displayed heterogeneity responses of its two subtypes. In one subtype, Cu was transported with metal transporters and chelated with Cu chaperons in the cytoplasm. Excess Cu disturbed oxidative phosphorylation and induced reactive oxygen species production. However, in the other subtype, endocytosis was mainly responsible for Cu internalization, which was sequestered in membrane-bound granules. Collectively, our results provided the first mRNA expression profile of hemocytes in oysters and revealed the heterogeneity responses under Cu exposure.

The effect of maternal iron deficiency on zinc and copper levels and on genes of zinc and copper metabolism during pregnancy in the rat

Fe deficiency is relatively common in pregnancy and has both short- and long-term consequences. However, little is known about the effect on the metabolism of other micronutrients. A total of fifty-four female rats were fed control (50 mg Fe/kg) or Fe-deficient diets (7·5 mg/kg) before and during pregnancy. Maternal liver, placenta and fetal liver were collected at day 21 of pregnancy for Cu and Zn analysis and to measure expression of the major genes of Cu and Zn metabolism. Cu levels increased in the maternal liver (P=0·002) and placenta (P=0·018) of Fe-deficient rats. Zn increased (P<0·0001) and Cu decreased (P=0·006) in the fetal liver. Hepatic expression of the Cu chaperones antioxidant 1 Cu chaperone (P=0·042) and cytochrome c oxidase Cu chaperone (COX17, P=0·020) decreased in the Fe-deficient dams, while the expression of the genes of Zn metabolism was unaltered. In the placenta, Fe deficiency reduced the expression of the chaperone for superoxide dismutase 1, Cu chaperone for superoxide dismutase (P=0·030), ceruloplasmin (P=0·042) and Zn transport genes, ZRT/IRT-like protein 4 (ZIP4, P=0·047) and Zn transporter 1 (ZnT1, P=0·012). In fetal liver, Fe deficiency increased COX17 (P=0·020), ZRT/IRT-like protein 14 (P=0·036) and ZnT1 (P=0·0003) and decreased ZIP4 (P=0·004). The results demonstrate that Fe deficiency during pregnancy has opposite effects on Cu and Zn levels in the fetal liver. This may, in turn, alter metabolism of these nutrients, with consequences for development in the fetus and the neonate.

Selenium, copper and iron in veterinary medicine-From clinical implications to scientific models

Diseases related to copper, selenium or iron overload or deficiency are common and well-described in large animal veterinary medicine. Some of them certainly have the potential to serve as useful animal models for ongoing research in the field of trace elements. Obvious advantages of large animal models compared to laboratory animal models like rats and mice are the option of long-term, consecutive examinations of progressive deficient or toxic stages and the opportunity to collect various, high volume samples for repeated measurements. Nevertheless, close cooperation between scientific disciplines is necessary as scientists using high sophisticated analytical methods and equipment are not regularly in touch with scientists working with large animal diseases. This review will give an introduction into some typical animal diseases related to trace elements and will present approaches where the animal diseases were used already as a model for interdisciplinary research.

Identification of reference genes for quantitative real-time PCR studies in human cell lines under copper and zinc exposure

Accurate quantification depends on normalization of the measured gene expression data. In particular, gene expression studies with exposure to metals are challenging due their toxicity and redox-active properties. Here, we assessed the stability of potential reference genes in three cell lines commonly used to study metal cell metabolism: Caco-2 (colon), HepG2 (liver) and THP-1 (peripheral blood) under copper (Cu) or zinc (Zn) exposure. We used combined statistical tools to identify the best reference genes from a set of eleven candidates, which included traditional "housekeeping" genes such as GAPDH and B-ACTIN, in cell lines exposed to high and low, Zn and Cu concentrations. The expression stabilities of ATP5B (ATP synthase) and CYC1 (subunits of the cytochrome) were the highest considering the effect of Zn and Cu treatments whereas SDHA (succinate dehydrogenase) was found to be the most unstable gene. Even though the transcriptional effect of Zn and Cu is very different in term of redox properties, the same best reference genes were identified when Zn or Cu treatments were analyzed together. Our results indicate that ATP5B/CYC1 are the best candidates for reference genes after metal exposure, which can be used as a suitable starting point to evaluate gene expression with other metals or in different cell types in human models.

Copper and hypoxia modulate transcriptional and mitochondrial functional-biochemical responses in warm acclimated rainbow trout (Oncorhynchus mykiss)

To survive in changing environments fish utilize a wide range of biological responses that require energy. We examined the effect of warm acclimation on the electron transport system (ETS) enzymes and transcriptional responses to hypoxia and copper (Cu) exposure in fish. Rainbow trout (Oncorhynchus mykiss) were acclimated to cold (11 °C; control) and warm (20 °C) temperatures for 3 weeks followed by exposure to Cu, hypoxia or both for 24 h. Activities of ETS enzyme complexes I-IV (CI-CIV) were measured in liver and gill mitochondria. Analyses of transcripts encoding for proteins involved in mitochondrial respiration (cytochrome c oxidase subunits 4-1 and 2: COX4-1 and COX4-2), metal detoxification/stress response (metallothioneins A and B: MT-A and MT-B) and energy sensing (AMP-activated protein kinase α1: AMPKα1) were done in liver mitochondria, and in whole liver and gill tissues by RT-qPCR. Warm acclimation inhibited activities of ETS enzymes while effects of Cu and hypoxia depended on the enzyme and thermal acclimation status. The genes encoding for COX4-1, COX4-2, MT-A, MT-B and AMPKα1 were strongly and tissue-dependently altered by warm acclimation. While Cu and hypoxia clearly increased MT-A and MT-B transcript levels in all tissues, their effects on COX4-1, COX4-2 and AMPKα1 mRNA levels were less pronounced. Importantly, warm acclimation differentially altered COX4-2/COX4-1 ratio in liver mitochondria and gill tissue. The three stressors showed both independent and joint actions on activities of ETS enzymes and transcription of genes involved in energy metabolism, stress response and metals homeostasis. Overall, we unveiled novel interactive effects that should not be overlooked in real world situations wherein fish normally encounter multiple stress factors.

Assessing chaperone for Zn, Cu-superoxide dismutase as an indicator of copper deficiency in malnourished children

It is not clear how frequent is copper deficiency in humans. Current copper markers are not sensitive enough to detect early copper deficiency and new markers are needed. CCS is a candidate to become a copper biomarker.

OBJECTIVE

Measuring CCS mRNA relative expression in malnourished children and compare results (a) with those of the same children after nutritional recovery and (b) with well-nourished children.

METHOD

On admission to the protocol and after 15 day nutritional treatment, severely (G1=18) and moderately (G2=10) malnourished children were compared with well-nourished healthy controls (G3=15), measuring anthropometric indicators, blood biochemistry, Cu, Fe and Zn serum concentrations, ceruloplasmin, C Reactive protein and mRNA abundance of CCS, SOD and MT2 in peripheral mononuclear cells.

RESULT

In malnourished groups, mean serum copper concentration was below the cut-off on admission to hospital and increased after 15 days (t-test, p<0.01). On admission to protocol, CCS mRNA abundance in G1 and G2 was higher than in G3 (one way ANOVA, p<0.001). After 15 days, CCS expression decreased as expected (t-test, p<0.001). Initial SOD mRNA relative abundance was higher in study groups than controls and also between G1 and G2 (One way ANOVA, both p<0.01); after 15 days, G1 and G2 were not different (t-test, NS). MT2A abundance of transcripts did not follow a clear change pattern.

CONCLUSION

CCS mRNA abundance responded as expected, being higher in malnourished children than in controls; nutritional recovery in these latter resulted in decreasing expression of the chaperone, supporting the hypothesis that CCS may be a copper biomarker.

Changes in copper concentrations affect the protein levels but not the mRNA levels of copper chaperones in human umbilical vein endothelial cells

Copper chaperones are critical regulators of intracellular copper metabolism and distribution. The present study was undertaken to investigate the effects of changes in copper concentrations on the abundance of copper chaperones. Human umbilical vein endothelial cells (HUVECs) were treated with siRNA targeting copper transporter 1 (CTR1) or tetraethylenepentamine (TEPA) to decrease, or with copper sulfide to increase, intracellular copper concentrations, assayed using an atomic absorption spectrophotometer. Western blot analyses showed that CTR1 silencing or TEPA treatment increased the protein levels of copper chaperone ATOX1 and copper chaperone for superoxide dismutase 1 (CCS-1), but decreased copper chaperone for cytochrome c oxidase (COX17). In contrast, copper supplementation decreased the protein levels of ATOX1 and CCS-1 and increased COX17. Real-time RT-PCR analyses found no difference in the mRNA levels of the copper chaperones examined under the conditions defined above. This study thus demonstrated that changes in copper concentrations alter the protein levels, but not the mRNA levels, of copper chaperones, suggesting a role of copper in the post-translational modification of these proteins.