Copper Transport Protein Antioxidant-1 Promotes Inflammatory Neovascularization via Chaperone and Transcription Factor Function

The crosstalk between copper-induced oxidative stress and cuproptosis: a novel potential anticancer paradigm

Copper is a crucial trace element that plays a role in various pathophysiological processes in the human body. Copper also acts as a transition metal involved in redox reactions, contributing to the generation of reactive oxygen species (ROS). Under prolonged and increased ROS levels, oxidative stress occurs, which has been implicated in different types of regulated cell death. The recent discovery of cuproptosis, a copper-dependent regulated cell death pathway that is distinct from other known regulated cell death forms, has raised interest to researchers in the field of cancer therapy. Herein, the present work aims to outline the current understanding of cuproptosis, with an emphasis on its anticancer activities through the interplay with copper-induced oxidative stress, thereby providing new ideas for therapeutic approaches targeting modes of cell death in the future.

Atox1-cyclin D1 loop activity is critical for survival of tumor cells with inactivated TP53

The search for relevant molecular targets is one of the main tasks of modern tumor chemotherapy. To successfully achieve this, it is necessary to have the most complete understanding of the functioning of a transcriptional apparatus of the cell, particularly related to proliferation. The p53 protein plays an important role in regulating processes such as apoptosis, repair, and cell division, and the loss of its functionality often accompanies various types of tumors and contributes to the development of chemoresistance. Additionally, the proliferative activity of tumor cells is closely related to the metabolism of transition metals. For example, the metallochaperone Atox1 - a copper transporter protein - acts as a transcription activator for cyclin D1, promoting progression through the G1/S phase of the cell cycle. On the other hand, p53 suppresses cyclin D1 at the transcriptional level, thereby these proteins have divergent effects on cell cycle progression. However, the contribution of the interaction between these proteins to cell survival is poorly understood. This work demonstrates that not only exists a positive feedback loop between Atox1 and cyclin D1 but also that the activity of this loop depends on the status of the TP53 gene. Upon inactivation of TP53 in A549 and HepG2 cell lines, the expression of ATOX1 and CCND1 genes is enhanced, and their suppression in these cells leads to pronounced apoptosis. This fundamental observation may be useful in selecting more precise interventions for combined therapy of p53-negative tumors.

Cuproptosis in cancer: biological implications and therapeutic opportunities

Cuproptosis, a newly identified copper (Cu)-dependent form of cell death, stands out due to its distinct mechanism that sets it apart from other known cell death pathways. The molecular underpinnings of cuproptosis involve the binding of Cu to lipoylated enzymes in the tricarboxylic acid cycle. This interaction triggers enzyme aggregation and proteotoxic stress, culminating in cell death. The specific mechanism of cuproptosis has yet to be fully elucidated. This newly recognized form of cell death has sparked numerous investigations into its role in tumorigenesis and cancer therapy. In this review, we summarized the current knowledge on Cu metabolism and its link to cancer. Furthermore, we delineated the molecular mechanisms of cuproptosis and summarized the roles of cuproptosis-related genes in cancer. Finally, we offered a comprehensive discussion of the most recent advancements in Cu ionophores and nanoparticle delivery systems that utilize cuproptosis as a cutting-edge strategy for cancer treatment.

Endothelial Drp1 Couples VEGF-induced Redox Signaling with Glycolysis Through Cysteine Oxidation to Drive Angiogenesis

Angiogenesis plays a vital role for postnatal development and tissue repair following ischemia. Reactive oxygen species (ROS) generated by NADPH oxidases (NOXes) and mitochondria act as signaling molecules that promote angiogenesis in endothelial cells (ECs) which mainly relies on aerobic glycolysis for ATP production. However, the connections linking redox signaling with glycolysis are not well understood. The GTPase Drp1 is a member of the dynamin superfamily that moves from cytosol to mitochondria through posttranslational modifications to induce mitochondrial fission. The role of Drp1 in ROS-dependent VEGF signaling and angiogenesis in ECs has not been previously described. Here, we identify an unexpected function of endothelial Drp1 as a redox sensor, transmitting VEGF-induced H 2 O 2 signals to enhance glycolysis and angiogenesis. Loss of Drp1 expression in ECs inhibited VEGF-induced angiogenic responses. Mechanistically, VEGF rapidly induced the NOX4-dependent sulfenylation (CysOH) of Drp1 on Cys 644 , promoting disulfide bond formation with the metabolic kinase AMPK and subsequent sulfenylation of AMPK at Cys 299 / 304 via the mitochondrial fission-mitoROS axis. This cysteine oxidation of AMPK, in turn, enhanced glycolysis and angiogenesis. In vivo , mice with EC-specific Drp1 deficiency or CRISPR/Cas9-engineered "redox-dead" (Cys to Ala) Drp1 knock-in mutations exhibited impaired retinal angiogenesis and post-ischemic neovascularization. Our findings uncover a novel role for endothelial Drp1 in linking VEGF-induced mitochondrial redox signaling to glycolysis through a cysteine oxidation-mediated Drp1-AMPK redox relay, driving both developmental and reparative angiogenesis.

Copper homeostasis dysregulation in respiratory diseases: a review of current knowledge

Cu is an essential micronutrient for various physiological processes in almost all human cell types. Given the critical role of Cu in a wide range of cellular processes, the local concentrations of Cu and the cellular distribution of Cu transporter proteins in the lung are essential for maintaining a steady-state internal environment. Dysfunctional Cu metabolism or regulatory pathways can lead to an imbalance in Cu homeostasis in the lungs, affecting both acute and chronic pathological processes. Recent studies have identified a new form of Cu-dependent cell death called cuproptosis, which has generated renewed interest in the role of Cu homeostasis in diseases. Cuproptosis differs from other known cell death pathways. This occurs through the direct binding of Cu ions to lipoylated components of the tricarboxylic acid cycle during mitochondrial respiration, leading to the aggregation of lipoylated proteins and the subsequent downregulation of Fe-S cluster proteins, which causes toxic stress to the proteins and ultimately leads to cell death. Here, we discuss the impact of dysregulated Cu homeostasis on the pathogenesis of various respiratory diseases, including asthma, chronic obstructive pulmonary disease, idiopathic interstitial fibrosis, and lung cancer. We also discuss the therapeutic potential of targeting Cu. This study highlights the intricate interplay between copper, cellular processes, and respiratory health. Copper, while essential, must be carefully regulated to maintain the delicate balance between necessity and toxicity in living organisms. This review highlights the need to further investigate the precise mechanisms of copper interactions with infections and immune inflammation in the context of respiratory diseases and explore the potential of therapeutic strategies for copper, cuproptosis, and other related effects.

Atox1 regulates macrophage polarization in intestinal inflammation via ROS-NLRP3 inflammasome pathway

BACKGROUND

Inflammation and oxidative stress play an important role in the pathophysiology of inflammatory bowel disease (IBD). This study aimed to explore the effects of copper chaperone Antioxidant-1 (Atox1) on macrophages in a mouse model of intestinal inflammation.

METHODS

A mouse model of TNBS-induced colitis was established and verified using the disease activity index. Atox1 conditional knockout mice were applied. The proportion of macrophages in colonic lamina propria mononuclear cells and ROS production were analyzed using flow cytometry. Inflammatory cytokines were measured using ELISA. Expression of macrophage M1/M2 polarization markers, p47phox, NLRP3, and Caspase-1 p20 was measured using quantitative RT-PCR and Western blotting.

RESULTS

Atox1 expression was up-regulated in colon tissues of TNBS-induced colitis mice. Macrophages isolated from TNBS-induced colitis mice showed M1 polarization and nuclear translocation of Atox1. Inhibiting copper chaperone activity decreased p47phox, ROS production, and M1 polarization induced by CuCl2 in macrophages. TNBS induced up-regulation of inflammatory cytokines, M1 polarization markers, and p47phox expression in mice, an effect which was preempted by Atox1 knockout. Inflammatory cytokines and expression of M1 polarization markers, p47phox, NLRP3, Caspase-1 p20 were also increased in macrophages isolated from TNBS-induced colitis mice. These changes were alleviated in mice with Atox1 knockout. The effects of Atox1 on macrophage polarization were mediated via the ROS-NLRP3 inflammasome pathway.

CONCLUSION

Atox1 plays a pro-inflammatory role, promotes M1 polarization of macrophages, and increases the concentrations of pro-inflammatory cytokines in intestinal tissue by regulating the ROS-NLRP3 inflammasome pathway. Atox1 is a potential therapeutic target in IBD.

Copper in Gynecological Diseases

Copper (Cu) is an essential micronutrient for the correct development of eukaryotic organisms. This metal plays a key role in many cellular and physiological activities, including enzymatic activity, oxygen transport, and cell signaling. Although the redox activity of Cu is crucial for enzymatic reactions, this property also makes it potentially toxic when found at high levels. Due to this dual action of Cu, highly regulated mechanisms are necessary to prevent both the deficiency and the accumulation of this metal since its dyshomeostasis may favor the development of multiple diseases, such as Menkes' and Wilson's diseases, neurodegenerative diseases, diabetes mellitus, and cancer. As the relationship between Cu and cancer has been the most studied, we analyze how this metal can affect three fundamental processes for tumor progression: cell proliferation, angiogenesis, and metastasis. Gynecological diseases are characterized by high prevalence, morbidity, and mortality, depending on the case, and mainly include benign and malignant tumors. The cellular processes that promote their progression are affected by Cu, and the mechanisms that occur may be similar. We analyze the crosstalk between Cu deregulation and gynecological diseases, focusing on therapeutic strategies derived from this metal.

Cardiomyocyte intercellular signalling increases oxidative stress and reprograms the global- and phospho-proteome of cardiac fibroblasts

Pathological reprogramming of cardiomyocyte and fibroblast proteome landscapes drive the initiation and progression of cardiac fibrosis. Although the secretome of dysfunctional cardiomyocytes is emerging as an important driver of pathological fibroblast reprogramming, our understanding of the downstream molecular players remains limited. Here, we show that cardiac fibroblast activation (αSMA+) and oxidative stress mediated by the secretome of TGFβ-stimulated cardiomyocytes is associated with a profound reprogramming of their proteome and phosphoproteome landscape. Within the fibroblast global proteome there was a striking dysregulation of proteins implicated in extracellular matrix, protein localisation/metabolism, KEAP1-NFE2L2 pathway, lysosomes, carbohydrate metabolism, and transcriptional regulation. Kinase substrate enrichment analysis of phosphopeptides revealed potential role of kinases (CK2, CDK2, PKC, GSK3B) during this remodelling. We verified upregulated activity of casein kinase 2 (CK2) in secretome-treated fibroblasts, and pharmacological CK2 inhibitor TBB (4,5,6,7-Tetrabromobenzotriazole) significantly abrogated fibroblast activation and oxidative stress. Our data provides molecular insights into cardiomyocyte to cardiac fibroblast crosstalk, and the potential role of CK2 in regulating cardiac fibroblast activation and oxidative stress.

The huge potential of targeting copper status in the treatment of colorectal cancer

Colorectal cancer (CRC) commonly leads to cancer deaths and is often diagnosed at advanced stages. It also faces difficulties due to the poor results of conventional treatments such as surgery, chemotherapy, and radiotherapy. Copper is a mineral nutrient whose intrinsic properties have a two-way effect on the production and treatment of cancer. Copper's redox properties allow it to be used in developing anti-cancer drugs, while its potential toxicity leads to oxidative stress and even cancer. Copper status is closely related to colorectal tumors' proliferation and metastasis. The study of the mechanisms of copper homeostasis, cuproplasia, and cuproptosis due to altered copper status plays a crucial role in developing anticancer drugs. Therefore, targeting alteration of copper status becomes a potential option for treating colorectal cancer. This review summarizes the mechanisms by which altered copper status causes CRC progression and emphasizes the potential of regulating copper status in treating CRC.

Protein disulfide isomerase A1 as a novel redox sensor in VEGFR2 signaling and angiogenesis

VEGFR2 signaling in endothelial cells (ECs) is regulated by reactive oxygen species (ROS) derived from NADPH oxidases (NOXs) and mitochondria, which plays an important role in postnatal angiogenesis. However, it remains unclear how highly diffusible ROS signal enhances VEGFR2 signaling and reparative angiogenesis. Protein disulfide isomerase A1 (PDIA1) functions as an oxidoreductase depending on the redox environment. We hypothesized that PDIA1 functions as a redox sensor to enhance angiogenesis. Here we showed that PDIA1 co-immunoprecipitated with VEGFR2 or colocalized with either VEGFR2 or an early endosome marker Rab5 at the perinuclear region upon stimulation of human ECs with VEGF. PDIA1 silencing significantly reduced VEGF-induced EC migration, proliferation and spheroid sprouting via inhibiting VEGFR2 signaling. Mechanistically, VEGF stimulation rapidly increased Cys-OH formation of PDIA1 via the NOX4-mitochondrial ROS axis. Overexpression of "redox-dead" mutant PDIA1 with replacement of the active four Cys residues with Ser significantly inhibited VEGF-induced PDIA1-CysOH formation and angiogenic responses via reducing VEGFR2 phosphorylation. Pdia1+/- mice showed impaired angiogenesis in developmental retina and Matrigel plug models as well as ex vivo aortic ring sprouting model. Study using hindlimb ischemia model revealed that PDIA1 expression was markedly increased in angiogenic ECs of ischemic muscles, and that ischemia-induced limb perfusion recovery and neovascularization were impaired in EC-specific Pdia1 conditional knockout mice. These results suggest that PDIA1 can sense VEGF-induced H2O2 signal via CysOH formation to promote VEGFR2 signaling and angiogenesis in ECs, thereby enhancing postnatal angiogenesis. The oxidized PDIA1 is a potential therapeutic target for treatment of ischemic vascular diseases.

Comparison of urine proteomes from tumor-bearing mice with those from tumor-resected mice

Objective

This study aimed to address on the most important concern of surgeons-whether to completely resect tumor. Urine can indicate early changes associated with physiological or pathophysiological processes. Based on these ideas, we conducted experiments to explore changes in the urine proteome between tumor-bearing mice and tumor-resected mice.

Method

The tumor-bearing mouse model was established with MC38 mouse colon cancer cells, and the mice were divided into the control group, tumor-resected group, and tumor-bearing group. Urine was collected 7 and 30 days after tumor resection. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was used to identify the urine proteome, which was analyzed for differentially expressed proteins and functional annotation.

Results

(1) Seven days after tumor resection, 20 differentially expressed proteins distinguished the tumor-resected group and the tumor-bearing group. The identified biological processes included circadian rhythm, Notch signaling pathway, leukocyte cell-cell adhesion, and heterophilic cell-cell adhesion via plasma membrane cell adhesion molecules. (2) Thirty days after tumor resection, 33 differentially expressed proteins distinguished the tumor-resected group and the tumor-bearing group. The identified biological processes included cell adhesion; complement activation, the alternative pathway; the immune system process; and angiogenesis. (3) The difference in the urine proteome between the tumor-resected group and the healthy control group was smaller 30 days after tumor resection.

Conclusion

Changes in the urinary proteome can reflect the complete resection of MC38 tumors.

Disulfiram Enhances the Antineoplastic Activity and Sensitivity of Murine Hepatocellular Carcinoma to 5-FU via Redox Management

The efficacy of anticancer drug 5-FU is suppressed due to various factors, including severe side effects and decreased insensitivity during prolonged chemotherapy. Elevated endogenous copper (Cu) levels are one of the prominent hallmark features of cancer cells. In the present investigation, this feature was targeted in diethyl nitrosamine-phenobarbital-induced hepatocellular carcinoma (HCC) in a rat model system by an established anticancer drug, 5-FU, co-administered with copper and its chelating agent, disulfiram. After treatment with the test chemicals in HCC-induced rats, blood and liver samples were subjected to biochemical, molecular, and histopathological analyses. The analysis revealed that reactive oxygen species-mediated oxidative stress is the crucial etiological reason for the pathogenesis of HCC in rats, as evidenced by the significantly compromised activity of major antioxidant enzymes and elevated levels of oxidative damaged products with major histological alterations compared to the control. However, the combination of 5-FU with DSF demonstrated a significant improvement in most of the parameters, followed by 5-FU-Cu in the combination-treated groups. The combination treatment improved the histological details and triggered apoptosis in the cancer cells to a remarkable extent, as the levels of cleaved PARP and caspase-3 were significantly higher than those in the HCC rats treated with the drug alone. The present study envisages that manipulating the Cu-level greatly enhances the antineoplastic activity of 5-FU and sensitizes cancer cells to the increased efficacy of the drug.

AKT-driven epithelial-mesenchymal transition is affected by copper bioavailability in HER2 negative breast cancer cells via a LOXL2-independent mechanism

BACKGROUND

The main mechanism underlying cancer dissemination is the epithelial to mesenchymal transition (EMT). This process is orchestrated by cytokines like TGFβ, involving "non-canonical" AKT- or STAT3-driven pathways. Recently, the alteration of copper homeostasis seems involved in the onset and progression of cancer.

METHODS

We expose different breast cancer cell lines, including two triple negative (TNBC) ones, an HER2 enriched and one cell line representative of the Luminal A molecular subtype, to short- or long-term copper-chelation by triethylenetetramine (TRIEN). We analyse changes in the expression of EMT markers (E-cadherin, fibronectin, vimentin and αSMA), in the levels and activity of extracellular matrix components (LOXL2, fibronectin and MMP2/9) and of copper homeostasis markers by Western blot analyses, immunofluorescence, enzyme activity assays and RT-qPCR. Boyden Chamber and wound healing assays revealed the impact of copper chelation on cell migration. Additionally, we explored whether perturbation of copper homeostasis affects EMT prompted by TGFβ. Metabolomic and lipidomic analyses were applied to search the effects of copper chelation on the metabolism of breast cancer cells. Finally, bioinformatics analysis of data on breast cancer patients obtained from different databases was employed to correlate changes in kinases and copper markers with patients' survival.

RESULTS

Remarkably, only HER2 negative breast cancer cells differently responded to short- or long-term exposure to TRIEN, initially becoming more aggressive but, upon prolonged exposure, retrieving epithelial features, reducing their invasiveness. This phenomenon may be related to the different impact of the short and prolonged activation of the AKT kinase and to the repression of STAT3 signalling. Bioinformatics analyses confirmed the positive correlation of breast cancer patients' survival with AKT activation and up-regulation of CCS. Eventually, metabolomics studies demonstrate a prevalence of glycolysis over mitochondrial energetic metabolism and of lipidome changes in TNBC cells upon TRIEN treatment.

CONCLUSIONS

We provide evidence of a pivotal role of copper in AKT-driven EMT activation, acting independently of HER2 in TNBC cells and via a profound change in their metabolism. Our results support the use of copper-chelators as an adjuvant therapeutic strategy for TNBC.

Relationship between copper and immunity: The potential role of copper in tumor immunity

Copper is an essential trace element in an organism, and changes in copper levels in vivo often indicate a diseased state. Copper and immunity have been discussed since the last century, with copper deficiency significantly affecting the development and function of the immune system, such as increased host susceptibility to various pathogens, decreased number and impaired function of neutrophils, reduced antibacterial activity of macrophages, decreased proliferation of splenocytes, impaired B cell ability to produce antibodies and impaired function of cytotoxic T lymphocyte and helper T cells. In the past 20 years, some studies have shown that copper ions are related to the development of many tumors, including lung cancer, acute lymphoid leukaemia, multiple myeloma and other tumors, wherein copper ion levels were significantly elevated, and current studies reveal that copper ions are involved in the development, growth and metastasis of tumors through various pathways. Moreover, recent studies have shown that copper ions can regulate the expression of PD-L1, thus, attention should be paid to the important role of copper in tumor immunity. By exploring and studying copper ions and tumor immunity, new insights into tumor immunity could be generated and novel therapeutic approaches to improve the clinical prognosis of patients can be provided.

Regulation, genomics, and clinical characteristics of cuproptosis regulators in pan-cancer

Background

Cuproptosis, a copper-dependent controlled cell death, is a novel form of cell death that differs from known cell death mechanisms; however, its overall regulation in cancer remains elusive.

Methods

Multiple open-source bioinformatic platforms were used to comprehensively elucidate the expression levels, prognostic efficiency, potential biological functions, genomic and epigenetic characteristics, immune microenvironment, and drug sensitivity of cuproptosis regulators (ATP7A, ATP7B, DLAT, DLD, FDX1, GLS, LIAS, LIPT1, MTF1, NLRP3, PDHA1, PDHB, and SLC31A1) in pan-cancer.

Results

Cuproptosis-related genes (CRGs) were upregulated in most cancers tested. In KIRC, KIRP, LGG, MESO, and PCPG, most highly expressed CRGs predicted a better prognosis but poorer prognosis in patients with ACC, LIHC, and UCEC. Pathway analysis confirmed that cuproptosis regulators were associated with the metabolism-related pathways. The expression of MTF1, NLRP3, and SLC31A1 was positively related with ImmuneScore, StromalScore, and ESTIMATEScore in almost all types of tumor, whereas ATP7B, DLAT, DLD, LIAS, PDHA1, and PDHB were significantly negatively correlated with the scores. In addition, CRGs were significantly correlated with RNA stemness score, DNA stemness score, microsatellite instability, and tumor mutational burden. The expression of ATP7A, ATP7B, LIAS, and DLAT was significantly positively correlated with the drug sensitivity of Docetaxel. ATP7A, LIAS, and FDX1 were significantly negatively correlated with the drug sensitivity of UNC0638, XMD13−2, YM201636, and KIN001−260.

Conclusions

The altered genomic and clinical characteristics of cuproptosis regulators were comprehensively elucidated, providing a preliminary basis for understanding the functions of cuproptosis in pan-cancer.

Effect of Copper on the Function of Isolated Porcine Kidneys Stored Using Simple Hypothermia

Renal ischemia in the peri-transplant period causes a number of changes that adversely affect the initiation of normal vital functions in grafts after transplantation. To minimise the extent of ischemic damage, organs are stored in preservation fluid. The components of the fluid are supposed to ensure stabilisation of the cell cytoskeleton, protect against oxygen free radicals, reduce cell swelling, and ensure endothelial cell integrity. The aim of this study was to analyse the protective effect of Cu2+, as a component of Biolasol preservative fluid, in the prevention of nephron damage occurring during the graft storage period. Analyses of the effectiveness of copper in the presence of prolactin added to Biolasol fluid were also carried out. Forty isolated pig slaughter kidneys were used in the study, avoiding the use of laboratory animals. The kidneys were stored using simple hypothermia. After 2 h and 48 h of graft storage, selected biochemical indicators of renal function were determined in the collected perfusates. The addition of Cu2+ at a dose of 1 µg/L to the composition of Biolasol fluid was found to affect the generation of ischemic damage in the isolated pig kidney. The intensity of the occurrence of these processes is exacerbated by the presence of prolactin at a dose of 0.1 µg/L.

Copper-Dependent Kinases and Their Role in Cancer Inception, Progression and Metastasis

In recent years, copper function has been expanded beyond its consolidated role as a cofactor of enzyme catalysis. Recent papers have demonstrated a new dynamic role for copper in the regulation of cell signaling pathways through direct interaction with protein kinases, modulating their activity. The activation of these pathways is exacerbated in cancer cells to sustain the different steps of tumor growth and dissemination. This review will focus on a novel proposed role for the transition metal copper as a regulator of cell signaling pathways through direct interaction with known protein kinases, which exhibit binding domains for this metal. Activation of these pathways in cancer cells supports both tumor growth and dissemination. In addition to the description of the results recently reported in the literature on the subject, relevance will be given to the possibility of controlling the cellular levels of copper and its homeostatic regulators. Overall, these findings may be of central relevance in order to propose copper and its homeostatic regulators as possible targets for novel therapies, which may act synergistically to those already existing to control cancer growth and dissemination.

Whole-Transcriptome Sequencing Analyses of Nuclear Antixoxidant-1 in Endothelial Cells: Role in Inflammation and Atherosclerosis

Inflammation, oxidative stress, and copper (Cu) play an important role in cardiovascular disease, including atherosclerosis. We previously reported that cytosolic Cu chaperone antioxidant-1 (Atox1) translocates to the nucleus in response to inflammatory cytokines or exogenous Cu and that Atox1 is localized at the nucleus in the endothelium of inflamed atherosclerotic aorta. However, the roles of nuclear Atox1 and their function are poorly understood. Here we showed that Atox1 deficiency in ApoE-/- mice with a Western diet exhibited a significant reduction of atherosclerotic lesion formation. In vitro, adenovirus-mediated overexpression of nuclear-targeted Atox1 (Ad-Atox1-NLS) in cultured human endothelial cells (ECs) increased monocyte adhesion and reactive oxygen species (ROS) production compared to control cells (Ad-null). To address the underlying mechanisms, we performed genome-wide mapping of Atox1-regulated targets in ECs, using an unbiased systemic approach integrating sequencing data. Combination of ChIP-Seq and RNA-Seq analyses in ECs transfected with Ad-Atox1-NLS or Ad-null identified 1387 differentially expressed genes (DEG). Motif enrichment assay and KEGG pathway enrichment analysis revealed that 248 differentially expressed genes, including inflammatory and angiogenic genes, were regulated by Atox1-NLS, which was then confirmed by real-time qPCR. Among these genes, functional analysis of inflammatory responses identified CD137, CSF1, and IL5RA as new nuclear Atox1-targeted inflammatory genes, while CD137 is also a key regulator of Atox1-NLS-induced ROS production. These findings uncover new nuclear Atox1 downstream targets involved in inflammation and ROS production and provide insights into the nuclear Atox1 as a potential therapeutic target for the treatment of inflammatory diseases such as atherosclerosis.

New diagnostic and therapeutic strategies for myocardial infarction via nanomaterials

Myocardial infarction is lethal to patients because of insufficient blood perfusion to vital organs. Several attempts have been made to improve its prognosis, among which nanomaterial research offers an opportunity to address this problem at the molecular level and has the potential to improve disease prevention, diagnosis, and treatment significantly. Up to now, nanomaterial-based technology has played a crucial role in broad novel diagnostic and therapeutic strategies for cardiac repair. This review summarizes various nanomaterial applications in myocardial infarction from multiple aspects, including high precision detection, pro-angiogenesis, regulating immune homeostasis, and miRNA and stem cell delivery vehicles. We also propose promising research hotspots that have not been reported much yet, such as conjugating pro-angiogenetic elements with nanoparticles to construct drug carriers, developing nanodrugs targeting other immune cells except for macrophages in the infarcted myocardium or the remote region. Though most of those strategies are preclinical and lack clinical trials, there is tremendous potential for their further applications in the future.

Interleukin-22 Deficiency Reduces Angiotensin II-Induced Aortic Dissection and Abdominal Aortic Aneurysm in ApoE-/- Mice

Background

Our previous study showed that interleukin-22 (IL-22) levels were increased in patients with aortic dissection (AD). This study evaluated the effects of IL-22 on AD/abdominal aortic aneurysm (AAA) formation in angiotensin II (Ang II)-infused ApoE-/- mice.

Methods

ApoE-/- mice were treated with Ang II for 28 days, and IL-22 expression was examined. In addition, the effects of IL22 deficiency on AAA/AD formation induced by Ang II infusion in ApoE-/- mice were investigated. ApoE-/-IL-22-/- mice were transplanted with bone marrow cells isolated from ApoE-/- mice or ApoE-/-IL-22-/- mice, and AAA/AD formation was observed.

Results

IL-22 expression was increased in both the aortas and serum of ApoE-/- mice after Ang II infusion and was mainly derived from aortic CD4+ T lymphocytes (CD4+ TCs). IL-22 deficiency significantly reduced the AAA/AD formation as well as the maximal aortic diameter in Ang II-infused ApoE-/- mice. Decreased elastin fragmentation and reduced fibrosis were observed in the aortas of ApoE-/-IL-22-/- mice compared with ApoE-/- mice. The deletion of IL-22 also decreased aortic M1 macrophage differentiation, alleviated M1 macrophage-induced oxidative stress, and reduced aortic smooth muscle cell loss. Furthermore, M1 macrophage-induced oxidative stress was worsened and AAA/AD formation was promoted in ApoE-/-IL-22-/- mice that received transplanted bone marrow cells from ApoE-/- mice compared with those that were transplanted with bone marrow cells isolated from ApoE-/-IL-22-/- mice.

Conclusions

IL-22 deficiency inhibits AAA/AD formation by inhibiting M1 macrophage-induced oxidative stress. IL-22 potentially represents a promising new target for preventing the progression of AAA/AD.

Dichotomous Role of Tumor Necrosis Factor in Pulmonary Barrier Function and Alveolar Fluid Clearance

Alveolar-capillary leak is a hallmark of the acute respiratory distress syndrome (ARDS), a potentially lethal complication of severe sepsis, trauma and pneumonia, including COVID-19. Apart from barrier dysfunction, ARDS is characterized by hyper-inflammation and impaired alveolar fluid clearance (AFC), which foster the development of pulmonary permeability edema and hamper gas exchange. Tumor Necrosis Factor (TNF) is an evolutionarily conserved pleiotropic cytokine, involved in host immune defense against pathogens and cancer. TNF exists in both membrane-bound and soluble form and its mainly -but not exclusively- pro-inflammatory and cytolytic actions are mediated by partially overlapping TNFR1 and TNFR2 binding sites situated at the interface between neighboring subunits in the homo-trimer. Whereas TNFR1 signaling can mediate hyper-inflammation and impaired barrier function and AFC in the lungs, ligand stimulation of TNFR2 can protect from ventilation-induced lung injury. Spatially distinct from the TNFR binding sites, TNF harbors within its structure a lectin-like domain that rather protects lung function in ARDS. The lectin-like domain of TNF -mimicked by the 17 residue TIP peptide- represents a physiological mediator of alveolar-capillary barrier protection. and increases AFC in both hydrostatic and permeability pulmonary edema animal models. The TIP peptide directly activates the epithelial sodium channel (ENaC) -a key mediator of fluid and blood pressure control- upon binding to its α subunit, which is also a part of the non-selective cation channel (NSC). Activity of the lectin-like domain of TNF is preserved in complexes between TNF and its soluble TNFRs and can be physiologically relevant in pneumonia. Antibody- and soluble TNFR-based therapeutic strategies show considerable success in diseases such as rheumatoid arthritis, psoriasis and inflammatory bowel disease, but their chronic use can increase susceptibility to infection. Since the lectin-like domain of TNF does not interfere with TNF's anti-bacterial actions, while exerting protective actions in the alveolar-capillary compartments, it is currently evaluated in clinical trials in ARDS and COVID-19. A more comprehensive knowledge of the precise role of the TNFR binding sites versus the lectin-like domain of TNF in lung injury, tissue hypoxia, repair and remodeling may foster the development of novel therapeutics for ARDS.

FKBP52 in Neuronal Signaling and Neurodegenerative Diseases: A Microtubule Story

The FK506-binding protein 52 (FKBP52) belongs to a large family of ubiquitously expressed and highly conserved proteins (FKBPs) that share an FKBP domain and possess Peptidyl-Prolyl Isomerase (PPIase) activity. PPIase activity catalyzes the isomerization of Peptidyl-Prolyl bonds and therefore influences target protein folding and function. FKBP52 is particularly abundant in the nervous system and is partially associated with the microtubule network in different cell types suggesting its implication in microtubule function. Various studies have focused on FKBP52, highlighting its importance in several neuronal microtubule-dependent signaling pathways and its possible implication in neurodegenerative diseases such as tauopathies (i.e., Alzheimer disease) and alpha-synucleinopathies (i.e., Parkinson disease). This review summarizes our current understanding of FKBP52 actions in the microtubule environment, its implication in neuronal signaling and function, its interactions with other members of the FKBPs family and its involvement in neurodegenerative disease.

Role of copper nanoparticles in wound healing for chronic wounds: literature review

Chronic wounds are defined as wounds that fail to proceed through the normal phases of wound healing in an orderly and timely manner. The most common and inevitable impairment to wound healing is the installation of an infection, usually in the case of chronic wounds. Therefore, the objective of the present review was to identify the importance of copper nanoparticles in dressings for wound healing. Nanoparticles such as silver, gold and copper combat infectious processes through the inhibition of protein synthesis, peroxidation of the cell membrane and destroying the nucleic acids of bacteria and viruses. Among bioactive nanoparticles, copper plays a complex role in various cells, it modulates several cytokines and growth factor mechanisms of action and is essentially involved in all stages of the wound healing process. More importantly, copper plays a key role in skin regeneration and angiogenesis and accelerates the healing process through induction of vascular endothelial growth factor (VEGF) and angiogenesis by hypoxia-induced factor-1-alpha (HIF-1α) action where copper enhances HIF-1α expression and HIF-1α binding to the critical motifs in the promoter and putative enhancer regions of HIF-1-regulated genes.

Cysteine oxidation of copper transporter CTR1 drives VEGFR2 signalling and angiogenesis

VEGFR2 (KDR/Flk1) signaling in endothelial cells (ECs) is essential for developmental and reparative angiogenesis. Reactive oxygen species (ROS) and copper (Cu) are also involved.in these processes. However, their inter-relationship is poorly understood. The role of endothelial Cu importer CTR1 in VEGFR2 signaling and angiogenesis in vivo is hitherto unknown. Here we show that CTR1 functions as a previously unrecognized redox sensor to promote angiogenesis in ECs. CTR1-depleted ECs showed reduced VEGF-induced VEGFR2 signaling and angiogenic responses. Mechanistically, CTR1 was rapidly sulfenylated at Cys189 in cytosolic C-terminus upon VEGF stimulation, which induced CTR1-VEGFR2 disulfide bond formation and their co-internalization to early endosomes, driving sustained VEGFR2 signaling. In vivo, EC-specific Ctr1-deficient mice or CRISPR/Cas9-generated “redox-dead” Cys to Ala Ctr1 knock-in mutant mice had impaired developmental and reparative angiogenesis. Thus, oxidation of CTR1 at Cys189 promotes VEGFR2 internalization and signaling to enhance angiogenesis. Our study uncovers an important mechanism for ROS sensing through CTR1 to drive neovascularization.

Copper in the tumor microenvironment and tumor metastasis

Copper (Cu), an essential micronutrient, plays an essential role in several physiological processes, including cell proliferation and angiogenesis; however, its dysregulation induces oxidative stress and inflammatory responses. Significant Cu accumulation is observed in several tumor tissues. The bioavailability of intracellular Cu is tightly controlled by Cu transporters, including Cu transporter 1 (CTR1) and Cu-transporting P-type ATPase α and β (ATP7A and ATP7B), and Cu chaperones, including Cu chaperone for superoxide dismutase 1 (CCS) and antioxidant-1 (Atox-1). In several tumor tissues, these abnormalities that induce intra­cellular Cu accumulation are involved in tumor progression. In addition, functional disturbance in Cu-containing secretory enzymes, such as superoxide dismutase 3 (SOD3), and lysyl oxidase enzymes (LOX and LOXL1–4) with abnormal Cu dynamics plays a key role in tumor metastasis. For example, the loss of SOD3 in tumor tissues induces oxidative stress, which promotes neovascularization and epithelial-to-mesenchymal transition (EMT). LOX promotes collagen crosslinking, which functions in the metastatic niche formation. Accordingly, restricted Cu regulation may be a novel strategy for the inhibition of tumor metastasis. However, it is unclear how these Cu disturbances occur in tumor tissues and the exact molecular mechanisms underlying Cu secretory enzymes. In this review article, I discuss the role of Cu transporters, Cu chaperones, and Cu-containing secretory enzymes in tumor progression to better understand the role of Cu homeostasis in tumor tissues.

Role of Copper on Mitochondrial Function and Metabolism

Copper is essential for life processes like energy metabolism, reactive oxygen species detoxification, iron uptake, and signaling in eukaryotic organisms. Mitochondria gather copper for the assembly of cuproenzymes such as the respiratory complex IV, cytochrome c oxidase, and the antioxidant enzyme superoxide dismutase 1. In this regard, copper plays a role in mitochondrial function and signaling involving bioenergetics, dynamics, and mitophagy, which affect cell fate by means of metabolic reprogramming. In mammals, copper homeostasis is tightly regulated by the liver. However, cellular copper levels are tissue specific. Copper imbalances, either overload or deficiency, have been associated with many diseases, including anemia, neutropenia, and thrombocytopenia, as well as tumor development and cancer aggressivity. Consistently, new pharmacological developments have been addressed to reduce or exacerbate copper levels as potential cancer therapies. This review goes over the copper source, distribution, cellular uptake, and its role in mitochondrial function, metabolic reprograming, and cancer biology, linking copper metabolism with the field of regenerative medicine and cancer.

Targeting the Copper Transport System to Improve Treatment Efficacies of Platinum-Containing Drugs in Cancer Chemotherapy

The platinum (Pt)-containing antitumor drugs including cisplatin (cis-diamminedichloroplatinum II, cDDP), carboplatin, and oxaliplatin, have been the mainstay of cancer chemotherapy. These drugs are effective in treating many human malignancies. The major cell-killing target of Pt drugs is DNA. Recent findings underscored the important roles of Pt drug transport system in cancer therapy. While many mechanisms have been proposed for Pt-drug transport, the high-affinity copper transporter (hCtr1), Cu chaperone (Atox1), and Cu exporters (ATP7A and ATP7B) are also involved in cDDP transport, highlighting Cu homeostasis regulation in Pt-based cancer therapy. It was demonstrated that by reducing cellular Cu bioavailable levels by Cu chelators, hCtr1 is transcriptionally upregulated by transcription factor Sp1, which binds the promoters of Sp1 and hCtr1. In contrast, elevated Cu poisons Sp1, resulting in suppression of hCtr1 and Sp1, constituting the Cu-Sp1-hCtr1 mutually regulatory loop. Clinical investigations using copper chelator (trientine) in carboplatin treatment have been conducted for overcoming Pt drug resistance due in part to defective transport. While results are encouraging, future development may include targeting multiple steps in Cu transport system for improving the efficacies of Pt-based cancer chemotherapy. The focus of this review is to delineate the mechanistic interrelationships between Cu homeostasis regulation and antitumor efficacy of Pt drugs.

Interference between copper transport systems and platinum drugs

Cisplatin, or cis-diamminedichloridoplatinum(II) cis-[PtCl₂(NH₃)₂], is a platinum-based anticancer drug largely used for the treatment of various types of cancers, including testicular, ovarian and colorectal carcinomas, sarcomas, and lymphomas. Together with other platinum-based drugs, cisplatin triggers malignant cell death by binding to nuclear DNA, which appears to be the ultimate target. In addition to passive diffusion across the cell membrane, other transport systems, including endocytosis and some active or facilitated transport mechanisms, are currently proposed to play a pivotal role in the uptake of platinum-based drugs. In this review, an updated view of the current literature regarding the intracellular transport and processing of cisplatin will be presented, with special emphasis on the plasma membrane copper permease CTR1, the Cu-transporting ATPases, ATP7A and ATP7B, located in the trans-Golgi network, and the soluble copper chaperone ATOX1. Their role in eliciting cisplatin efficacy and their exploitation as pharmacological targets will be addressed.

The P-type ATPase transporter ATP7A promotes angiogenesis by limiting autophagic degradation of VEGFR2

VEGFR2 (KDR/Flk1) signaling in endothelial cells (ECs) plays a central role in angiogenesis. The P-type ATPase transporter ATP7A regulates copper homeostasis, and its role in VEGFR2 signaling and angiogenesis is entirely unknown. Here, we describe the unexpected crosstalk between the Copper transporter ATP7A, autophagy, and VEGFR2 degradation. The functional significance of this Copper transporter was demonstrated by the finding that inducible EC-specific ATP7A deficient mice or ATP7A-dysfunctional ATP7Amut mice showed impaired post-ischemic neovascularization. In ECs, loss of ATP7A inhibited VEGF-induced VEGFR2 signaling and angiogenic responses, in part by promoting ligand-induced VEGFR2 protein degradation. Mechanistically, VEGF stimulated ATP7A translocation from the trans-Golgi network to the plasma membrane where it bound to VEGFR2, which prevented autophagy-mediated lysosomal VEGFR2 degradation by inhibiting autophagic cargo/adapter p62/SQSTM1 binding to ubiquitinated VEGFR2. Enhanced autophagy flux due to ATP7A dysfunction in vivo was confirmed by autophagy reporter CAG-ATP7Amut -RFP-EGFP-LC3 transgenic mice. In summary, our study uncovers a novel function of ATP7A to limit autophagy-mediated degradation of VEGFR2, thereby promoting VEGFR2 signaling and angiogenesis, which restores perfusion recovery and neovascularization. Thus, endothelial ATP7A is identified as a potential therapeutic target for treatment of ischemic cardiovascular diseases.

The Multifaceted Roles of Copper in Cancer: A Trace Metal Element with Dysregulated Metabolism, but Also a Target or a Bullet for Therapy

In the human body, copper (Cu) is a major and essential player in a large number of cellular mechanisms and signaling pathways. The involvement of Cu in oxidation-reduction reactions requires close regulation of copper metabolism in order to avoid toxic effects. In many types of cancer, variations in copper protein levels have been demonstrated. These variations result in increased concentrations of intratumoral Cu and alterations in the systemic distribution of copper. Such alterations in Cu homeostasis may promote tumor growth or invasiveness or may even confer resistance to treatments. Once characterized, the dysregulated Cu metabolism is pinpointing several promising biomarkers for clinical use with prognostic or predictive capabilities. The altered Cu metabolism in cancer cells and the different responses of tumor cells to Cu are strongly supporting the development of treatments to disrupt, deplete, or increase Cu levels in tumors. The metallic nature of Cu as a chemical element is key for the development of anticancer agents via the synthesis of nanoparticles or copper-based complexes with antineoplastic properties for therapy. Finally, some of these new therapeutic strategies such as chelators or ionophores have shown promising results in a preclinical setting, and others are already in the clinic.

Cross-Talk between NADPH Oxidase and Mitochondria: Role in ROS Signaling and Angiogenesis

Angiogenesis, a new vessel formation from the pre-existing ones, is essential for embryonic development, wound repair and treatment of ischemic heart and limb diseases. However, dysregulated angiogenesis contributes to various pathologies such as diabetic retinopathy, atherosclerosis and cancer. Reactive oxygen species (ROS) derived from NADPH oxidase (NOX) as well as mitochondria play an important role in promoting the angiogenic switch from quiescent endothelial cells (ECs). However, how highly diffusible ROS produced from different sources and location can communicate with each other to regulate angiogenesis remains unclear. To detect a localized ROS signal in distinct subcellular compartments in real time in situ, compartment-specific genetically encoded redox-sensitive fluorescence biosensors have been developed. Recently, the intercellular communication, “cross-talk”, between ROS derived from NOX and mitochondria, termed “ROS-induced ROS release”, has been proposed as a mechanism for ROS amplification at distinct subcellular compartments, which are essential for activation of redox signaling. This “ROS-induced ROS release” may represent a feed-forward mechanism of localized ROS production to maintain sustained signaling, which can be targeted under pathological conditions with oxidative stress or enhanced to promote therapeutic angiogenesis. In this review, we summarize the recent knowledge regarding the role of the cross-talk between NOX and mitochondria organizing the sustained ROS signaling involved in VEGF signaling, neovascularization and tissue repair.

Lysyl Oxidase (LOX): Functional Contributions to Signaling Pathways

Cu-dependent lysyl oxidase (LOX) plays a catalytic activity-related, primary role in the assembly of the extracellular matrix (ECM), a dynamic structural and regulatory framework which is essential for cell fate, differentiation and communication during development, tissue maintenance and repair. LOX, additionally, plays both activity-dependent and independent extracellular, intracellular and nuclear roles that fulfill significant functions in normal tissues, and contribute to vascular, cardiac, pulmonary, dermal, placenta, diaphragm, kidney and pelvic floor disorders. LOX activities have also been recognized in glioblastoma, diabetic neovascularization, osteogenic differentiation, bone matrix formation, ligament remodeling, polycystic ovary syndrome, fetal membrane rupture and tumor progression and metastasis. In an inflammatory context, LOX plays a role in diminishing pluripotent mesenchymal cell pools which are relevant to the pathology of diabetes, osteoporosis and rheumatoid arthritis. Most of these conditions involve mechanisms with complex cell and tissue type-specific interactions of LOX with signaling pathways, not only as a regulatory target, but also as an active player, including LOX-mediated alterations of cell surface receptor functions and mutual regulatory activities within signaling loops. In this review, we aim to provide insight into the diverse ways in which LOX participates in signaling events, and explore the mechanistic details and functional significance of the regulatory and cross-regulatory interactions of LOX with the EGFR, PDGF, VEGF, TGF-β, mechano-transduction, inflammatory and steroid signaling pathways.

Rapid Evaluation of CRISPR Guides and Donors for Engineering Mice

Although the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/ CRISPR associated protein 9 (Cas9) technique has dramatically lowered the cost and increased the speed of generating genetically engineered mice, success depends on using guide RNAs and donor DNAs which direct efficient knock-out (KO) or knock-in (KI). By Sanger sequencing DNA from blastocysts previously injected with the same CRISPR components intended to produce the engineered mice, one can test the effectiveness of different guide RNAs and donor DNAs. We describe in detail here a simple, rapid (three days), inexpensive protocol, for amplifying DNA from blastocysts to determine the results of CRISPR point mutation KIs. Using it, we show that (1) the rate of KI seen in blastocysts is similar to that seen in mice for a given guide RNA/donor DNA pair, (2) a donor complementary to the variable portion of a guide integrated in a more all-or-none fashion, (3) donor DNAs can be used simultaneously to integrate two different mutations into the same locus, and (4) by placing silent mutations about every 6 to 10 bp between the Cas9 cut site and the desired mutation(s), the desired mutation(s) can be incorporated into genomic DNA over 30 bp away from the cut at the same high efficiency as close to the cut.

The molecular mechanisms of copper metabolism and its roles in human diseases

Copper is an essential element in cells; it can act as either a recipient or a donor of electrons, participating in various reactions. However, an excess of copper ions in cells is detrimental as these copper ions can generate free radicals and increase oxidative stress. In multicellular organisms, copper metabolism involves uptake, distribution, sequestration, and excretion, at both the cellular and systemic levels. Mammalian enterocytes take in bioavailable copper ions from the diet in a Ctr1-dependent manner. After incorporation, cuprous ions are delivered to ATP7A, which pumps Cu⁺ from enterocytes into the blood. Copper ions arrive at the liver through the portal vein and are incorporated into hepatocytes by Ctr1. Then, Cu⁺ can be secreted into the bile or the blood via the Atox1/ATP7B/ceruloplasmin route. In the bloodstream, this micronutrient can reach peripheral tissues and is again incorporated by Ctr1. In peripheral tissue cells, cuprous ions are either sequestrated by molecules such as metallothioneins or targeted to utilization pathways by chaperons such as Atox1, Cox17, and CCS. Copper metabolism must be tightly controlled in order to achieve homeostasis and avoid disorders. A hereditary or acquired copper unbalance, including deficiency, overload, or misdistribution, may cause or aggravate certain diseases such as Menkes disease, Wilson disease, neurodegenerative diseases, anemia, metabolic syndrome, cardiovascular diseases, and cancer. A full understanding of copper metabolism and its roles in diseases underlies the identification of novel effective therapies for such diseases.

Effects of nano-copper on maize yield and inflammatory response in mice

Objective(s):

Copper (Cu) is an essential dietary supplement in animal feeds, which plays an important role in maintaining the balance of all living organisms. Copper nanoparticles (nCu) participate in catalysing activities of multiple antioxidant/defensive enzymes and exerts pro-inflammatory and pro-apoptotic effects on systemic organs and tissues. The present study explored whether nCu affects maize growth and yield and grain mineral nutrients as well as physiological functions in mice.

Materials and Methods:

Maize seeds were treated with nCu (20 mg/kg and 1000 mg/kg dry weight (DW)) and their grain productions were used for mouse feed. For testing of autoimmune response, mice were treated with nCu at concentration of 2 mg/l and 1000 mg/l and ultimately serum biochemical indicators, numbers and activation of immune cells infiltrated in mouse spleens were examined.

Results:

Treatment of maize seeds with nCu at dose of 20 mg/kg DW, but not 1000 mg/kg DW enhanced germination rate, plant growth and grain yield as well as grain mineral nutrients as compared to control group. Importantly, administration of mice with 1000 mg/l nCu resulted in their morphological change due to excessive accumulation of nCu in liver and blood, leading to inflammatory responses involved in upregulated expression of serum biochemical indicators of liver and kidney as well as increased infiltration and activation of splenic immune cells.

Conclusion:

nCu concentration at 20 mg/kg DW facilitated the morphological and functional development of maize plants, whose production was safe to feed mice.

Molecular Insights Into Lysyl Oxidases in Cartilage Regeneration and Rejuvenation

Articular cartilage remains among the most difficult tissues to regenerate due to its poor self-repair capacity. The lysyl oxidase family (LOX; also termed as protein-lysine 6-oxidase), mainly consists of lysyl oxidase (LO) and lysyl oxidase-like 1-4 (LOXL1-LOXL4), has been traditionally defined as cuproenzymes that are essential for stabilization of extracellular matrix, particularly cross-linking of collagen and elastin. LOX is essential in the musculoskeletal system, particularly cartilage. LOXs-mediated collagen cross-links are essential for the functional integrity of articular cartilage. Appropriate modulation of the expression or activity of certain LOX members selectively may become potential promising strategy for cartilage repair. In the current review, we summarized the advances of LOX in cartilage homeostasis and functioning, as well as copper-mediated activation of LOX through hypoxia-responsive signaling axis during recent decades. Also, the molecular signaling network governing LOX expression has been summarized, indicating that appropriate modulation of hypoxia-responsive-signaling-directed LOX expression through manipulation of bioavailability of copper and oxygen is promising for further clinical implications of cartilage regeneration, which has emerged as a potential therapeutic approach for cartilage rejuvenation in tissue engineering and regenerative medicine. Therefore, targeted regulation of copper-mediated hypoxia-responsive signalling axis for selective modulation of LOX expression may become potential effective therapeutics for enhanced cartilage regeneration and rejuvenation in future clinical implications.

Functional analyses of copper transporter genes in the human liver cell line HepG2

Copper (Cu) is an essential element regulated by four genes (hCTR1, hATOX1, hATP7A, and hATP7B in humans and zctr1, zatox1, zatp7a, and zatp7b in zebrafish) in copper uptake, distribution, and transport in animal cells. Zebrafish (Danio rerio) shows a higher endogenous ratio of zatp7a to zatp7b in the liver, is relatively intolerant to copper ions and has a different zatp7a and zatp7b expression patterns in different organs. As high-affinity copper transporters, both zctr1 and hCTR1 increased copper toxicity, whereas hATOX1 and zatox1 slightly reduced copper toxicity in HepG2 cells after copper administration for 24 h. The transfected zatp7b functioned in HepG2 cells as effectively as hATP7B after both 24-h and 96-h copper exposure, but zatp7a failed to function in HepG2 cells as effectively as hATP7A. Our findings suggest that ATP7A dysfunction would increase cytotoxicity in the liver; the reason for zebrafish's copper intolerance could be the bulk dysfunction and abnormal localization of zATP7A.

Copper promotion of myocardial regeneration

IMPACT STATEMENT

Copper promotes angiogenesis, but the mechanistic insights have not been fully elucidated until recently. In addition, the significance of copper promotion of angiogenesis in myocardial regeneration was increasingly revealed. Copper critically participates in the regulation of hypoxia-inducible factor 1 (HIF-1) of angiogenic gene expression. Interestingly, myocardial ischemia causes copper efflux from the heart, leading to suppression of angiogenesis, although HIF-1α, the critical subunit of HIF-1, remains accumulated in the ischemic myocardium. Strategies targeting copper specific delivery to the ischemic myocardium lead to selective activation of HIF-1-regulated angiogenic gene expression. Vascularization of the ischemic myocardium re-establishes the tissue injury microenvironment, and rebuilds the conduit for communication between the tissue injury signals and the remote regenerative responses including stem cells. This process promotes myocardial regeneration. Thus, a simple and effective copper supplementation to the ischemic myocardium would become a novel therapeutic approach to the treatment of patients with ischemic heart diseases.

Nuclear translocation of Atox1 potentiates activin A-induced cell migration and colony formation in colon cancer

Background

Colorectal cancer remains a deadly cancer due to metastatic disease. To understand the molecular mechanisms of metastasis in colon cancer, we investigated whether the copper chaperone antioxidant-1 (Atox1) protein plays a role in this process. Recent findings indicate that Atox1 protein has transcription factor activities and plays a vital role in cell proliferation in cancer cells. However, the role of Atox1 in metastasis has not been examined.

Methods

Atox1 expression was determined by immunofluorescence in a tissue microarray generated from a spectrum of CRC patients. Subcellular fractionation of colon cancer cell lines SW480 and SW620 cells was used to examine the cellular location of Atox1 in the face of activin A, a cytokine that stimulates colon cancer metastasis. Atox1 expression was genetically manipulated and cellular migration measured through trans-well assay and proliferation measured by colony formation assays.

Results

Here we demonstrate that in patients with metastatic colon cancer, there is a significant increase in the expression of nuclear Atox1. Interestingly, the metastatic CRC cell line SW620 has increased nuclear localization of Atox1 compared to its related non-metastatic cell line SW480. Further, inhibition of endogenous Atox1 by siRNA in SW620 decreased colony formation and reactive oxygen species generation via decreased expression of Atox1 targets cyclin D1 and NADPH oxidase subunit p47 phox, respectively. Additionally, overexpression of nuclear-targeted but not copper binding domain-mutated Atox1 in SW480 cells increased colony formation and cell migration that was further augmented by activin A stimulation, a known enhancer of colon cancer metastasis.

Conclusions

Our findings suggest that nuclear Atox1 might be a new therapeutic target as well as a new biomarker for metastatic colorectal cancer.

Single-cell tracking demonstrates copper chaperone Atox1 to be required for breast cancer cell migration

Copper ions are needed for several hallmarks of cancer. However, the involved pathways, mechanisms, and copper-binding proteins are mostly unknown. We recently found that cytoplasmic Antioxidant 1 copper chaperone (Atox1), which is up-regulated in breast cancer, is localized at the lamellipodia edges of aggressive breast cancer cells. To reveal molecular insights into a putative role in cell migration, we here investigated breast cancer cell (MDA-MB-231) migration by video microscopy as a function of Atox1. Tracking of hundreds of individual cells (per condition) over a 9-h time series revealed that cell migration velocity and directionality are significantly reduced upon Atox1 silencing in the cells. Because silencing of the copper transporter ATP7A also reduced cell migration, these proteins appear to be on the same pathway, suggesting that their well-known copper transport activity is involved. In-cell proximity ligation assays demonstrated that Atox1, ATP7A, and the proenzyme of lysyl oxidase (LOX; copper-loaded via ATP7A) are all in close proximity and that LOX activity is reduced upon Atox1 silencing in the cells. Since LOX is an established player in cancer cell migration, our results imply that Atox1 mediates breast cancer cell migration via coordinated copper transport in the ATP7A-LOX axis. Because individual cell migration is an early step in breast cancer metastasis, Atox1 levels in tumor cells may be a predictive measure of metastasis potential and serve as a biomarker for copper depletion therapy.

Copper Transporter ATP7A (Copper-Transporting P-Type ATPase/Menkes ATPase) Limits Vascular Inflammation and Aortic Aneurysm Development: Role of MicroRNA-125b

OBJECTIVE

Copper (Cu) is essential micronutrient, and its dysregulation is implicated in aortic aneurysm (AA) development. The Cu exporter ATP7A (copper-transporting P-type ATPase/Menkes ATPase) delivers Cu via the Cu chaperone Atox1 (antioxidant 1) to secretory Cu enzymes, such as lysyl oxidase, and excludes excess Cu. Lysyl oxidase is shown to protect against AA formation. However, the role and mechanism of ATP7A in AA pathogenesis remain unknown. Approach and Results: Here, we show that Cu chelator markedly inhibited Ang II (angiotensin II)-induced abdominal AA (AAA) in which ATP7A expression was markedly downregulated. Transgenic ATP7A overexpression prevented Ang II-induced AAA formation. Conversely, Cu transport dysfunctional ATP7A^mut/+/ApoE^-/- mice exhibited robust AAA formation and dissection, excess aortic Cu accumulation as assessed by X-ray fluorescence microscopy, and reduced lysyl oxidase activity. In contrast, AAA formation was not observed in Atox1^-/-/ApoE^-/- mice, suggesting that decreased lysyl oxidase activity, which depends on both ATP7A and Atox1, was not sufficient to develop AAA. Bone marrow transplantation suggested importance of ATP7A in vascular cells, not bone marrow cells, in AAA development. MicroRNA (miR) array identified miR-125b as a highly upregulated miR in AAA from ATP7A^mut/+/ApoE^-/- mice. Furthermore, miR-125b target genes (histone methyltransferase Suv39h1 and the NF-κB negative regulator TNFAIP3 [tumor necrosis factor alpha induced protein 3]) were downregulated, which resulted in increased proinflammatory cytokine expression, aortic macrophage recruitment, MMP (matrix metalloproteinase)-2/9 activity, elastin fragmentation, and vascular smooth muscle cell loss in ATP7A^mut/+/ApoE^-/- mice and reversed by locked nucleic acid-anti-miR-125b infusion.

CONCLUSIONS

ATP7A downregulation/dysfunction promotes AAA formation via upregulating miR-125b, which augments proinflammatory signaling in a Cu-dependent manner. Thus, ATP7A is a potential therapeutic target for inflammatory vascular disease.

Novel interaction of antioxidant-1 with TRAF4: role in inflammatory responses in endothelial cells

NADPH oxidase (NOX)-derived reactive oxygen species (ROS) and copper (Cu), an essential micronutrient, have been implicated in vascular inflammatory diseases. We reported that in proinflammatory cytokine TNF-α-stimulated endothelial cells (ECs), cytosolic Cu chaperone antioxidant-1 (Atox1) functions as a Cu-dependent transcription factor for the NOX organizer p47phox, thereby increasing ROS-dependent inflammatory gene expression. However, the role and mechanism of Atox1 nuclear translocation in inflamed ECs remain unclear. Using enface staining and nuclear fractionation, here we show that Atox1 was localized in the nucleus in inflamed aortas from ApoE^-/- mice with angiotensin II infusion on a high-fat diet, while it was found in cytosol in those from control mice. In cultured human ECs, TNF-α stimulation promoted Atox1 nuclear translocation within 15 min, which was associated with Atox1 binding to TNF-α receptor-associated factor 4 (TRAF4) in a Cu-dependent manner. TRAF4 depletion by siRNA significantly inhibited Atox1 nuclear translocation, p47phox expression, and ROS production as well as its downstream VCAM1/ICAM1 expression and monocyte adhesion to inflamed ECs, which were rescued by overexpression of nuclear targeted Atox1. Furthermore, Atox1 colocalized with TRAF4 at the nucleus in TNF-α-stimulated inflamed ECs and vessels. In summary, Cu-dependent Atox1 binding to TRAF4 plays an important role in Atox1 nuclear translocation and ROS-dependent inflammatory responses in TNF-α-stimulated ECs. Thus the Atox1-TRAF4 axis is a novel therapeutic target for vascular inflammatory disease such as atherosclerosis.

Folding of copper proteins: role of the metal?

Copper is a redox-active transition metal ion required for the function of many essential human proteins. For biosynthesis of proteins coordinating copper, the metal may bind before, during or after folding of the polypeptide. If the metal binds to unfolded or partially folded structures of the protein, such coordination may modulate the folding reaction. The molecular understanding of how copper is incorporated into proteins requires descriptions of chemical, thermodynamic, kinetic and structural parameters involved in the formation of protein-metal complexes. Because free copper ions are toxic, living systems have elaborate copper-transport systems that include particular proteins that facilitate efficient and specific delivery of copper ions to target proteins. Therefore, these pathways become an integral part of copper protein folding in vivo. This review summarizes biophysical-molecular in vitro work assessing the role of copper in folding and stability of copper-binding proteins as well as protein-protein copper exchange reactions between human copper transport proteins. We also describe some recent findings about the participation of copper ions and copper proteins in protein misfolding and aggregation reactions in vitro.

Copper homeostasis as target of both consolidated and innovative strategies of anti-tumor therapy

BACKGROUND

Copper was reported to be involved in the onset and progression of cancer. Proteins in charge of copper uptake and distribution, as well as cuproenzymes, are altered in cancer. More recently, proteins involved in signaling cascades, regulating cell proliferation, and anti-apoptotic protein factors were found to interact with copper. Therefore, therapeutic strategies using copper complexing molecules have been proposed for cancer therapy and used in clinical trials.

OBJECTIVES

This review will focus on novel findings about the involvement of copper and cupro-proteins in cancer dissemination process, epithelium to mesenchymal transition and vascularization. Particularly, implication of well-established (e.g. lysil oxidase) or newly identified copper-binding proteins (e.g. MEMO1), as well as their interplay, will be discussed. Moreover, we will describe recently synthesized copper complexes, including plant-derived ones, and their efficacy in contrasting cancer development.

CONCLUSIONS

The research on the involvement of copper in cancer is still an open field. Further investigation is required to unveil the mechanisms involved in copper delivery to the novel copper-binding proteins, which may identify other possible gene and protein targets for cancer therapy.

Tat-ATOX1 inhibits inflammatory responses via regulation of MAPK and NF-κB pathways

Antioxidant 1 (ATOX1) protein has been reported to exhibit various protective functions, including antioxidant and chaperone. However, the effects of ATOX1 on the inflammatory response has not been fully elucidated. Thus, we prepared cell permeable Tat-ATOX1 and studied the effects on lipopolysaccharide (LPS)- and 12-O-tetradecanoyl phorbol-13-acetate (TPA)-induced inflammation. Experimental results showed that transduced Tat-ATOX1 protein significantly suppressed LPS-induced intracellular reactive oxygen species (ROS). Also, Tat-ATOX1 protein markedly inhibited LPS- and TPA-induced inflammatory responses by decreasing cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) and further inhibited phosphorylation of mitogen activated protein kinases (MAPKs; JNK, ERK and p38) and the nuclear factor-kappaB (NF-κB) signaling pathway. These results indicate that the Tat-ATOX1 protein has a pivotal role in inflammation via inhibition of inflammatory responses, suggesting Tat-ATOX1 protein may offer a therapeutic strategy for inflammation.

Inhibition of Copper Transport Induces Apoptosis in Triple-Negative Breast Cancer Cells and Suppresses Tumor Angiogenesis

Treatment of advanced breast cancer remains challenging. Copper and some of the copper-dependent proteins are emerging therapeutic targets because they are essential for cell proliferation and survival, and have been shown to stimulate angiogenesis and metastasis. Here, we show that DCAC50, a recently developed small-molecule inhibitor of the intracellular copper chaperones, ATOX1 and CCS, reduces cell proliferation and elevates oxidative stress, triggering apoptosis in a panel of triple-negative breast cancer (TNBC) cells. Inhibition of ATOX1 activity with DCAC50 disrupts copper homeostasis, leading to increased copper levels, altered spatial copper redistribution, and accumulation of ATP7B to the cellular perinuclear region. The extent and impact of this disruption to copper homeostasis vary across cell lines and correlate with cellular baseline copper and glutathione levels. Ultimately, treatment with DCAC50 attenuates tumor growth and suppresses angiogenesis in a xenograft mouse model, and prevents endothelial cell network formation in vitro Co-treatment with paclitaxel and DCAC50 enhances cytotoxicity in TNBC and results in favorable dose reduction of both drugs. These data demonstrate that inhibition of intracellular copper transport targets tumor cells and the tumor microenvironment, and is a promising approach to treat breast cancer.

Copper in the suprachiasmatic circadian clock: A possible link between multiple circadian oscillators

The mammalian circadian clock in the suprachiasmatic nucleus (SCN) is very robust, able to coordinate our daily physiological and behavioral rhythms with exquisite accuracy. Simultaneously, the SCN clock is highly sensitive to environmental timing cues such as the solar cycle. This duality of resiliency and sensitivity may be sustained in part by a complex intertwining of three cellular oscillators: transcription/translation, metabolic/redox, and membrane excitability. We suggest here that one of the links connecting these oscillators may be forged from copper (Cu). Cellular Cu levels are highly regulated in the brain and peripherally, and Cu affects cellular metabolism, redox state, cell signaling, and transcription. We have shown that both Cu chelation and application induce nighttime phase shifts of the SCN clock in vitro and that these treatments affect glutamate, N-methyl-D-aspartate receptor, and associated signaling processes differently. More recently we found that Cu induces mitogen-activated protein kinase-dependent phase shifts, while the mechanisms by which Cu removal induces phase shifts remain unclear. Lastly, we have found that two Cu transporters are expressed in the SCN, and that one of these transporters (ATP7A) exhibits a day/night rhythm. Our results suggest that Cu homeostasis is tightly regulated in the SCN, and that changes in Cu levels may serve as a time cue for the circadian clock. We discuss these findings in light of the existing literature and current models of multiple coupled circadian oscillators in the SCN.

Copper Chaperone Atox1 Interacts with Cell Cycle Proteins

The anaphase-promoting complex (APC) is involved in several processes in the cell cycle, most prominently it facilitates the separation of the sister chromatids during mitosis, before cell division. Because of the key role in the cell cycle, APC is suggested as a putative target for anticancer agents. We here show that the copper chaperone Atox1, known for shuttling copper in the cytoplasm from Ctr1 to ATP7A/B in the secretory pathway, interacts with several APC subunits. Atox1 interactions with APC subunits were discovered by mass spectrometry of co-immunoprecipitated samples and further confirmed using proximity ligation assays in HEK293T cells. Upon comparing wild-type cells with those in which the Atox1 gene had been knocked out, we found that in the absence of Atox1 protein, cells have prolonged G2/M phases and a slower proliferation rate. Thus, in addition to copper transport for loading of copper-dependent enzymes, Atox1 may modulate the cell cycle by interacting with APC subunits.

Copper transporters and copper chaperones: roles in cardiovascular physiology and disease

Copper (Cu) is an essential micronutrient but excess Cu is potentially toxic. Its important propensity to cycle between two oxidation states accounts for its frequent presence as a cofactor in many physiological processes through Cu-containing enzymes, including mitochondrial energy production (via cytochrome c-oxidase), protection against oxidative stress (via superoxide dismutase), and extracellular matrix stability (via lysyl oxidase). Since free Cu is potentially toxic, the bioavailability of intracellular Cu is tightly controlled by Cu transporters and Cu chaperones. Recent evidence reveals that these Cu transport systems play an essential role in the physiological responses of cardiovascular cells, including cell growth, migration, angiogenesis and wound repair. In response to growth factors, cytokines, and hypoxia, their expression, subcellular localization, and function are tightly regulated. Cu transport systems and their regulators have also been linked to various cardiovascular pathophysiologies such as hypertension, inflammation, atherosclerosis, diabetes, cardiac hypertrophy, and cardiomyopathy. A greater appreciation of the central importance of Cu transporters and Cu chaperones in cell signaling and gene expression in cardiovascular biology offers the possibility of identifying new therapeutic targets for cardiovascular disease.

Copper chaperone antioxidant-1, Atox-1, is involved in the induction of SOD3 in THP-1 cells

Superoxide dismutase (SOD) 3, a copper (Cu)-containing anti-oxidative enzyme, plays a key role in extracellular redox homeostasis. Cu chaperone antioxidant-1 (Atox-1) not only delivers Cu ions to SOD3 at the trans-Golgi network, it also functions as a transcription factor of SOD3; however, the role of Atox-1 in the regulation of SOD3 during the monocytic differentiation of THP-1 cells has not yet been elucidated. A treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) induced the expression of the Cu transport protein ATP7A in THP-1 cells. On the other hand, the nuclear translocation of Atox-1 was detected in TPA-treated THP-1 cells, and was suppressed in the presence of the Cu chelator, bathocuproinedisulfonic acid. Furthermore, Atox-1 bound to the SOD3 promoter region in TPA-treated THP-1 cells. The overexpression of Atox-1 in THP-1 cells significantly enhanced TPA-elicited SOD3 expression, whereas its knockdown suppressed this induction. The present results demonstrate that Atox-1 functions as a key molecule in TPA-elicited SOD3 expression.