Copper sulfate-induced endoplasmic reticulum stress promotes hepatic apoptosis by activating CHOP, JNK and caspase-12 signaling pathways

The molecular mechanism and therapeutic landscape of copper and cuproptosis in cancer

Copper, an essential micronutrient, plays significant roles in numerous biological functions. Recent studies have identified imbalances in copper homeostasis across various cancers, along with the emergence of cuproptosis, a novel copper-dependent form of cell death that is crucial for tumor suppression and therapeutic resistance. As a result, manipulating copper levels has garnered increasing interest as an innovative approach to cancer therapy. In this review, we first delineate copper homeostasis at both cellular and systemic levels, clarifying copper's protumorigenic and antitumorigenic functions in cancer. We then outline the key milestones and molecular mechanisms of cuproptosis, including both mitochondria-dependent and independent pathways. Next, we explore the roles of cuproptosis in cancer biology, as well as the interactions mediated by cuproptosis between cancer cells and the immune system. We also summarize emerging therapeutic opportunities targeting copper and discuss the clinical associations of cuproptosis-related genes. Finally, we examine potential biomarkers for cuproptosis and put forward the existing challenges and future prospects for leveraging cuproptosis in cancer therapy. Overall, this review enhances our understanding of the molecular mechanisms and therapeutic landscape of copper and cuproptosis in cancer, highlighting the potential of copper- or cuproptosis-based therapies for cancer treatment.

The physiological role of copper: Dietary sources, metabolic regulation, and safety concerns

Copper plays an important physiological role in the body, with both deficiency and excess potentially impacting overall health. The body maintains a stringent copper metabolism mechanism to oversee absorption, utilization, storage, and elimination. Dietary consumption serves as the principal source of copper. The dietary factors may interfere with the absorption and metabolism of copper, leading to fluctuation of copper levels in the body. However, these dietary factors can also be strategically employed to facilitate the precise regulation of copper. This paper delved into the advancements in research concerning copper in food processing, including dietary sources of copper, the regulatory processes of copper metabolism and health implications of copper. The safety and its underlying mechanisms of excess copper were also highlighted. In particular, the paper examines the influence of dietary factors on the absorption and metabolism of copper, aiming to provide direction for accurate copper regulation and the creation of functional foods and pharmaceuticals.

Gut Microbiota and Its Metabolite Taurine-β-Muricholic Acid Contribute to Antimony- and/or Copper-Induced Liver Inflammation

Antimony and copper can contaminate vegetables and enter the human body through the digestive tract, inducing severe and extensive biotoxicity. However, the role of bile acids (BAs) in the pathogenesis of liver inflammation by antimony or copper has not been elucidated. Our results indicated that antimony and/or copper induced liver inflammation, causing the disruption of gut microbiota, with the down-regulation of probiotics and up-regulation of harmful bacteria closely correlated to liver inflammation. Targeted metabolomics of BAs showed that antimony and/or copper significantly up-regulated the levels of taurine-β-muricholic acid (T-β-MCA) in serum and liver, which was due to the reduction of Lactobacillus spp. A farnesoid X receptor (FXR) antagonist, T-β-MCA inhibited the FXR-SHP pathway in liver and FXR-FGF15 pathway in ileum, thereby promoting the transcription of cholesterol 7-alpha hydroxylase (CYP7A1) and increasing total bile acid concentrations, ultimately leading to liver inflammation. These findings provide new insights into the underlying mechanisms of antimony- and/or copper-induced liver inflammation.

Parkinson's Disease: The Neurodegenerative Enigma Under the "Undercurrent" of Endoplasmic Reticulum Stress

Parkinson's disease (PD), a prevalent neurodegenerative disorder, demonstrates the critical involvement of endoplasmic reticulum stress (ERS) in its pathogenesis. This review comprehensively examines the role and molecular mechanisms of ERS in PD. ERS represents a cellular stress response triggered by imbalances in endoplasmic reticulum (ER) homeostasis, induced by factors such as hypoxia and misfolded protein aggregation, which activate the unfolded protein response (UPR) through the inositol-requiring enzyme 1 (IRE1), protein kinase R-like endoplasmic reticulum kinase (PERK), and activating transcription factor 6 (ATF6) pathways. Clinical, animal model, and cellular studies have consistently demonstrated a strong association between PD and ERS. Abnormal expression of ERS-related molecules in PD patients' brains and cerebrospinal fluid (CSF) correlates with disease progression. In animal models (e.g., Drosophila and mice), ERS inhibition alleviates dopaminergic neuronal damage. Cellular experiments reveal that PD-mimicking pathological conditions induce ERS, while interactions between ERS and mitochondrial dysfunction promote neuronal apoptosis. Mechanistically, (1) pathological aggregation of α-synuclein (α-syn) and ERS mutually reinforce dopaminergic neuron damage; (2) leucine-rich repeat kinase 2 (LRRK2) gene mutations induce ERS through thrombospondin-1 (THBS1)/transforming growth factor beta 1 (TGF-β1) interactions; (3) molecules such as Parkin and PTEN-induced kinase 1 (PINK1) regulate ERS in PD. Furthermore, ERS interacts with mitochondrial dysfunction, oxidative stress, and neuroinflammation to exacerbate neuronal injury. Emerging therapeutic strategies show significant potential, including artificial intelligence (AI)-assisted drug design targeting ERS pathways and precision medicine approaches exploring non-pharmacological interventions such as personalized electroacupuncture. Future research should focus on elucidating ERS-related mechanisms and identifying novel therapeutic targets to develop more effective treatments for PD patients, ultimately improving their quality of life.

Endoplasmic Reticulum Stress: Implications in Diseases

Endoplasmic reticulum (ER) is a specialized organelle that plays a significant role in cellular function. The major functions of ER include protein synthesis and transport, folding of proteins, biosynthesis of lipids, calcium (Ca2+) storage, and redox balance. The loss of ER integrity results in the induction of ER stress within the cell due to the accumulation of unfolded, improperly folded proteins or changes in Ca2+ metabolism and redox balance of organelle. This ER stress commences the Unfolded Protein Response (UPR) that serves to counteract the ER stress via three sensors inositol requiring protein-1 (IRE1), protein kinase RNA-like ER kinase (PERK), and activating transcription factor-6 (ATF6) that serve to establish ER homeostasis and alleviates ER stress. Severe ER dysfunction ultimately results in the induction of apoptosis. Increasing shreds of evidence suggest the implication of ER stress in the development and progression of several diseases viz. tuberculosis, malaria, Alzheimer's disease, Parkinson's disease, diabetes, and cancer. Activation of ER stress can be beneficial for treating some diseases while inhibiting the process can be useful in others. A deeper understanding of these pathways can provide key insights in designing novel therapeutics to treat these diseases.

Tributyltin induces apoptosis in mammalian cells in vivo: a scoping review

The present review aimed to evaluate the apoptotic effect of tributyltin (TBT) exposure on mammalian tissues and cells in vivo. A search was conducted in specialized literature databases including Embase, Medline, Pubmed, Scholar Google, and Scopus for all manuscripts using the following keywords: "tributyltin", "apoptosis", "mammals", "mammalian cells', "eukaryotic cells", 'rodents', "rats", "mice" and "in vivo" for all data published until September 2023. A total of 16 studies were included. The studies have demonstrated that TBT exposure induces apoptosis in cells from various mammalian organs or tissues in vivo. TBT is capable to increase apoptotic cells, to activate proapoptotic proteins such as calpain, caspases, bax and beclin-1 and to inhibit antiapoptotic protein bcl-2. Additionally, TBT alters the ratio of bcl-2/bax which favor apoptosis. Therefore, the activation of enzymes such as calpain induces apoptosis mediated by ERS and caspases through the intrinsic apoptosis pathway. This review has demonstrated that TBT exposure induces apoptosis in mammalian tissues and cells in vivo.

Brucella suis S2 strain inhibits IRE1/caspase-12/caspase-3 pathway-mediated apoptosis of microglia HMC3 by affecting the ubiquitination of CALR

Neurobrucellosis represents a severe complication of brucellosis, posing a considerable risk to human health and quality of life. This condition arises from an increased susceptibility to chronic Brucella infection, a significant clinical challenge. One key factor contributing to chronic neurobrucellosis is the regulation of microglial apoptosis by Brucella; however, the exact molecular mechanisms remain largely unresolved. In this study, human microglial clone 3 (HMC3) cells were infected with Brucella suis vaccine strain S2 (B. suis S2) at varying multiplicity of infection (MOI) and durations to assess its effects on the IRE1/caspase-12/caspase-3 signaling pathway. Following the suppression of this pathway by B. suis S2, calreticulin (CALR) was identified through ubiquitin-modified proteomics (data accessible via ProteomeXchange, identifier PXD056006). To further investigate, CALR-overexpression and knockdown HMC3 cell lines were infected with B. suis S2 to elucidate the mechanism by which B. suis S2 inhibits apoptosis in HMC3 cells. In conclusion, our findings demonstrate that B. suis S2 suppresses HMC3 cell apoptosis via the IRE1/caspase-12/caspase-3 pathway by modulating CALR ubiquitination. This study provides a theoretical basis for exploring the mechanisms of neurobrucellosis and offers insights into its clinical treatment.IMPORTANCENeurobrucellosis is a severe complication impacting the central nervous system (CNS) due to neurological deficits caused by Brucella, with primary clinical features including meningitis, encephalitis, brain abscesses, and demyelinating lesions. These nonspecific symptoms often lead to misdiagnosis or delayed diagnosis, increasing the risk of recurrent or chronic neurobrucellosis infections. Consequently, persistent infection and relapse are critical challenges in the clinical management of neurobrucellosis, which are closely linked to Brucella's survival and replication within microglia. Interestingly, Brucella may inhibit microglia apoptosis by mitigating endoplasmic reticulum (ER) stress, though the precise molecular mechanisms remain largely unexplored. Thus, this study will elucidate the specific mechanisms by which Brucella suppresses microglial apoptosis and provide deeper insights into the molecular pathogenesis and clinical treatment of neurobrucellosis.

The Potential Mechanism of Cuproptosis in Hemocytes of the Pacific Oyster Crassostrea gigas upon Elesclomol Treatment

Cuproptosis is a novel cell death dependent on mitochondrial respiration and regulated by copper. While the study of it is mainly focused on tumor therapy, in the present study, two key cuproptosis-related genes, ferredoxin (FDX1) and dihydrolipoamide S-acetyltransferase (DLAT) homologs (designated as CgFDX1 and CgDLAT), were identified from Crassostrea gigas. CgFDX1 has a Fer2 domain with a 2Fe-2S cluster forming a unique ferredoxin. CgDLAT is composed of a biotin_lipoyl domain, an E3-binding domain, and a 2-oxoacid_dh domain. CgFDX1 and CgDLAT mRNA were expressed in all the examined tissues. After elesclomol treatment, both mRNA and protein expressions of them were reduced in the hemocytes. The mortality rate of the hemocytes increased significantly, and the hemocytes were accompanied with noticeable adhesive abnormalities and heightened secretion after elesclomol treatment. Additionally, the accumulation or depletion of actin was observed in the hemocytes. The integrity of the double membrane structure of the mitochondria was compromised, and the organization of mitochondrial cristae was disrupted. The contents of copper, malondialdehyde (MDA), pyruvic acid and mitoSOX as well as the ratio of cells with low mitochondrial potential increased significantly in the hemocytes upon elesclomol treatment and the content of citric acid decreased significantly. These findings suggest the potential presence of cuproptosis in oysters and its activation mechanism is relatively conserved in evolution.

Inducers of Autophagy and Cell Death: Focus on Copper Metabolism

Copper is an essential trace element in biological systems, playing a key role in various physiological functions, including redox reactions and energy metabolism. However, an imbalance in copper homeostasis can induce oxidative stress, mitochondrial dysfunction, and inhibition of the ubiquitin-proteasome system, ultimately leading to significant cytotoxicity and cell death. According to recent research, copper can bind to lipoylation sites on proteins involved in the tricarboxylic acid cycle, causing aggregation of lipoylated proteins, the loss of Fe-S cluster proteins, proteotoxic stress, and ultimately, cell death. This new type of programmed cell death is called "Cuproptosis". Furthermore, autophagy may be activated by a disruption in copper homeostasis, while it plays a dual role in regulating copper-induced cell death by acting both as an inhibitor of cell death and as a promoter of cytotoxicity. This review summarizes research progress on copper metabolic patterns, molecular mechanisms of copper-induced cell death, and mechanisms of copper-induced autophagy-cytotoxicity interactions. Meanwhile, the application of copper-induced cell death in cancer therapy is discussed, aiming to provide new insights and guiding future research toward advancing cancer therapy.

Residual hyperglycemia after successful treatment of a patient with severe copper sulfate poisoning

Copper sulfate is a frequently used copper compound in laboratory settings, with instances of poisoning being uncommon. A study conducted by the American Association of Poison Control Centers' National Poison Data System found that only 140 individuals were exposed to copper compounds over the course of a year, with five cases being intentional (Gummin et al., 2023). Severe poisoning from copper sulfate can result in isolated gastrointestinal injury (Galust et al., 2023), intravascular hemolysis (Adline et al., 2024), rhabdomyolysis (Richards et al., 2020), and other symptoms documented in the literature. However, there have been no reports of long-term uncontrolled hyperglycemia in patients with copper sulfate poisoning. This case study documents the treatment approach for a patient with unexplained, long-term, uncontrolled hyperglycemia, alongside multiple organ dysfunction resulting from intentional ingestion of a large dose of copper sulfate. This case report details the long-term complications in a patient's recovery from acute copper sulfate, highlighting the significance of ongoing monitoring and intervention.

miR-421-mediated suppression of FGF13 as a novel mechanism ameliorates cardiac hypertrophy by inhibiting endoplasmic reticulum stress

Pathological cardiac hypertrophy is an independent risk factor for heart failure. Currently, clinical treatments offer limited effectiveness, and both mortality and morbidity from cardiac hypertrophy and heart failure continue to be significant. Therefore, it is extremely urgent to find new intervention targets to prevent and alleviate pathological cardiac hypertrophy. In this study, we explored FGF13 expression and its upstream regulators in hypertrophic hearts. Firstly, we observed an increase in FGF13 expression levels in human hypertrophic myocardium tissues, as well as in mouse models of TAC-induced hypertrophy and in neonatal rat cardiomyocyte (NRCM) models induced by isoproterenol (ISO). Moreover, these elevated levels of FGF13 were shown to positively correlate with hypertrophic markers, including ANP and BNP. By using both gain-of-function and loss-of-function approaches in an in vitro hypertrophy model, we demonstrated that FGF13 knockdown could inhibit endoplasmic reticulum stress (ERS), thereby ameliorating cardiomyocyte hypertrophy. Meanwhile, we investigated the upstream regulators of FGF13 in hypertrophic hearts, and a dual-luciferase reporter assay confirmed that FGF13 is a direct target of miR-421. Overexpression of miR-421 decreased the protein level of FGF13 and ameliorated ISO-induced cardiomyocyte hypertrophy via modulating ER stress. In contrast, overexpression of FGF13 attenuated the ameliorative effect of miR-421 on ISO-induced cardiomyocyte hypertrophy. Taken together, the present results suggested that miR-421 ameliorated ISO-induced cardiomyocyte hypertrophy by negatively regulating FGF13 expression. This finding may offer a novel approach for the treatment of cardiac hypertrophy.

Regulation of chondrocyte apoptosis in osteoarthritis by endoplasmic reticulum stress

Osteoarthritis (OA), a common degenerative joint disease, is characterized by the apoptosis of chondrocytes as a primary pathophysiological change, with endoplasmic reticulum stress (ERS) playing a crucial role. It has been demonstrated that an imbalance in endoplasmic reticulum (ER) homeostasis can lead to ERS, activating three cellular adaptive response pathways through the unfolded protein response to restore ER homeostasis. Mild ERS exerts a protective effect on cells, while prolonged ERS that disrupts the self-regulatory balance of the ER activates apoptotic signaling pathways, leading to chondrocyte apoptosis and hastening OA progression. Hence, controlling the ERS signaling pathway and its apoptotic factors has become a critical focus for preventing and treating OA. This review aims to elucidate the key mechanisms of ERS pathway-induced apoptosis, associated targets, and regulatory pathways, offering valuable insights to enhance the mechanistic understanding of OA. It also reviews the mechanisms studied for ERS-related drugs or compounds for the treatment of OA.

Effect and underlying mechanism of a photochemotherapy dual-function nanodrug delivery system for head and neck squamous cell carcinoma

BACKGROUND

The novel nanomaterials PNA-TN (PN) and PNA-TN-Dox (PND) have been shown to have strong inhibitory effects on breast cancer; however, it is unclear whether PN and PND have anti-head and neck squamous cell carcinoma (HNSCC) activity, and their potential mechanisms of activity are unknown. So, our study aims to explore the therapeutic effects of PN and PND on HNSCC and their possible mechanisms.

METHODS

We used a series of phenotypic research to evaluate the effects of PN + Laser (L) and PND + L on the biological function of HNSCC cells in vitro and in vivo. We subsequently used mechanism research to examine changes in mRNA and protein expression related to apoptosis, epithelial‒mesenchymal transition (EMT), and the JNK signalling pathway.

RESULTS

Our study revealed that PN and PND have strong inhibitory effects on HNSCC cells both in vitro and in vivo. In vitro, PN and PND significantly inhibited the proliferation, migration, invasion and EMT ability of HNSCC cells and promoted apoptosis; the inhibitory effect in the PND + L group was significantly greater than that in the PN + L group. In vivo, both treatments led to significant reductions in tumour volume and weight. Notably, the tumour volume and weight in the PND + L group were significantly lower than those in the PN + L group. Mechanism research confirmed that PN + L activated the expression of apoptosis-related proteins and inhibited the expression of EMT-related proteins via the JNK pathway. Furthermore, the anti-HNSCC effect of PN + L was blocked after the use of a JNK pathway inhibitor.

CONCLUSION

Treatment with PN + L or PND + L significantly inhibited the malignant progress of HNSCC cells, and the therapeutic effect of PND + L was significantly stronger than that of PN + L. The JNK signalling pathway is a key mechanism by which PN exerts its anti-HNSCC activity.

Unveiling Cuproptosis: Mechanistic insights, roles, and leading advances in oncology

Copper, a vital micronutrient, performs essential functions in numerous biological settings. Its disrupted metabolism is implicated in both the initiation of tumors and therapeutic interventions for cancer, underscoring the critical necessity of preserving copper homeostasis. Cuproptosis, a regulated cell death (RCD) modulated by copper, is activated in response to elevated copper concentrations, prompting an investigation into its implication in oncogenesis. Within this review, an exploration is conducted into copper dynamics and homeostasis maintenance within cells. Furthermore, it delves into the mechanisms underlying cuproptosis and its interplay with signaling pathways implicated in cancer. The potential synergy between cuproptosis and ferroptosis and its impact on tumor immunomodulation is discussed. Additionally, promising avenues for addressing cuproptosis in cancer involve assessing the utility of copper chelators and ionophores. By addressing pressing questions surrounding cuproptosis and outlining its pivotal role in cancer pathogenesis and treatment, this review propounds targeting cuproptosis as a promising frontier in antitumor therapy, potentially revolutionizing cancer treatment strategies.

Deoxynivalenol-Induced Spleen Toxicity in Mice: Inflammation, Endoplasmic Reticulum Stress, Macrophage Polarization, and the Dysregulation of LncRNA Expression

The spleen is a primary target of deoxynivalenol (DON) toxicity, but its underlying molecular mechanisms remain unclear. This study investigates the effects of DON on inflammation, splenic macrophage polarization, endoplasmic reticulum (ER) stress, and transcriptome changes (mRNA and lncRNAs) in mouse spleen. We found that DON exposure at doses of 2.5 or 5 mg/kg BW significantly induced inflammation and polarized splenic macrophages towards the M1 phenotype. Additionally, DON activated PERK-eIF2α-ATF4-mediated ER stress and upregulated apoptosis-related proteins (caspase-12, caspase-3). The ER stress inhibitor, 4-Phenylbutyric acid, significantly alleviated DON-induced ER stress, apoptosis, and the M1 polarization of splenic macrophages. Transcriptome analysis identified 1968 differentially expressed (DE) lncRNAs and 2664 DE mRNAs in mouse spleen following DON exposure. Functional enrichment analysis indicated that the upregulated genes were involved in pathways associated with immunity, including Th17 cell differentiation, TNF signaling, and IL-17 signaling, while downregulated mRNAs were linked to cell survival and growth pathways. Furthermore, 370 DE lncRNAs were predicted to target 255 DE target genes associated with immune processes, including the innate immune response, interferon-beta response, cytokine production regulation, leukocyte apoptosis, and NF-κB signaling genes. This study provides new insights into the mechanisms underlying DON toxicity and its effects on the immune system.

The protective role of quercetin against copper-induced female reproductive toxicity: Insights from transcriptome analysis

Quercetin has been shown to mitigate the cytotoxic effects of heavy metals. While copper is an essential trace element for bodily functions, excessive intake has been linked to impaired female reproductive function. Transcriptome analysis was employed to identify genes that are differentially expressed in response to high copper and were validated through qRT-PCR and western blotting. ATP content and Tunel were used to identify the damage of mitochondrial and cell apoptosis. PPI analysis revealed that MKI67, TOPII, ASPM, CASP3, PLK1, and TTK are central proteins within the network. Additionally, exposure to elevated levels of copper resulted in the dysregulation of 86 genes associated with mitochondria. Conversely, treatment with quercetin (QUE) in combination with high copper led to the normalization of 42 mitochondria-related genes previously affected by high copper levels. Furthermore, CuSO4 decreases ATP content and induces cell apoptosis, which can be reversed by QUE. Results suggest that elevated copper levels could lead to oxidative stress and apoptosis by inducing mitochondrial damage, while QUE has the potential to mitigate these effects, ultimately safeguarding granulosa cells and halting the progression of cell death. This study provides novel insights into the molecular pathways involved in female reproductive toxicity caused by excessive copper exposure.

Photodynamic therapy of cancer using graphene nanomaterials

INTRODUCTION

High incidence and fatality rates of cancer remain a global challenge. The success of conventional treatment modalities is being questioned on account of adverse effects. Photodynamic therapy (PDT) is a potential alternative. It utilizes a combination of photosensitizer (PS), light and oxygen to target the tissues locally, thereby minimizing the damage to neighboring healthy tissues. Conventional PSs suffer from poor selectivity, high hydrophobicity and sub-optimal yield of active radicals. Graphene nanomaterials (GNs) exhibit interesting particulate and photophysical properties in the context of their use in PDT.

AREA COVERED

We focus on describing the mechanistic aspects of PDT-mediated elimination of cancer cells and the subsequent development of adaptive immunity. After covering up-to-date literature on the significant enhancement of PDT capability with GNs, we have discussed the probability of combining PDT with chemo-, immuno-, and photothermal therapy to make the treatment more effective.

EXPERT OPINION

GNs can be synthesized in various size ranges, and their biocompatibility can be improved through surface functionalization and doping. These can be used as PS to generate ROS or conjugated with other PS molecules for treating deep-seated tumors. With increasing evidence on biosafety, such materials offer hope as antitumor therapeutics.

Focus on cuproptosis: Exploring new mechanisms and therapeutic application prospects of cuproptosis regulation

Cuproptosis is a novel form of regulated cell death, which plays an important role in the physiological and pathological processes of the human body. Despite the increasing research on cuproptosis-related genes (CRGs) and their correlation with diseases, the pathogenesis of cuproptosis-related diseases remains unclear. Furthermore, there is a lack of reviews on the emerging technologies for regulating cuproptosis in disease treatment. This study delves into the copper-induced cell death mechanism, distinguishing cuproptosis from mechanisms like oxidative stress, glutathione synthesis inhibition, and ubiquitin-proteasome system inhibition. Several long-standing mysteries of diseases such as Wilson's disease and Menkes disease may be attributed to the occurrence of cuproptosis. In addition, we also review the detection indicators related to cuproptosis, providing targets for the diagnosis of cuproptosis-related diseases, and summarize the application value of cuproptosis in tumor therapy to better elucidate the impact of copper in cell death and diseases, and thus to promote the application prospects and possible strategies of cuproptosis-related substances, such as copper ion chelators, copper ion carriers, and copper nanomaterials, in disease therapy.

Targeting cuproptosis for cancer therapy: mechanistic insights and clinical perspectives

Cuproptosis is a newly identified form of cell death induced by excessive copper (Cu) accumulation within cells. Mechanistically, cuproptosis results from Cu-induced aggregation of dihydrolipoamide S-acetyltransferase, correlated with the mitochondrial tricarboxylic acid cycle and the loss of iron-sulfur cluster proteins, ultimately resulting in proteotoxic stress and triggering cell death. Recently, cuproptosis has garnered significant interest in tumor research due to its potential as a crucial therapeutic strategy against cancer. In this review, we summarized the cellular and molecular mechanisms of cuproptosis and its relationship with other types of cell death. Additionally, we reviewed the current drugs or strategies available to induce cuproptosis in tumor cells, including Cu ionophores, small compounds, and nanomedicine. Furthermore, we targeted cell metabolism and specific regulatory genes in cancer therapy to enhance tumor sensitivity to cuproptosis. Finally, we discussed the feasibility of targeting cuproptosis to overcome tumor chemotherapy and immunotherapy resistance and suggested future research directions. This study suggested that targeting cuproptosis could open new avenues for developing tumor therapy.

Mechanisms of cuproptosis and its relevance to distinct diseases

Copper is a trace element required by the organism, but once the level of copper exceeds the threshold, it becomes toxic and even causes death. The underlying mechanisms of copper-induced death are inconclusive, with different studies showing different opinions on the mechanism of copper-induced death. Multiple investigations have shown that copper induces oxidative stress, endoplasmic reticulum stress, nucleolar stress, and proteasome inhibition, all of which can result in cell death. The latest research elucidates a copper-dependent death and denominates it as cuproptosis. Cuproptosis takes place through the combination of copper and lipoylated proteins of the tricarboxylic acid cycle, triggering agglomeration of lipoylated proteins and loss of iron-sulfur cluster proteins, leading to proteotoxic stress and ultimately death. Given the toxicity and necessity of copper, abnormal levels of copper lead to diseases such as neurological diseases and cancer. The development of cancer has a high demand for copper, neurological diseases involve the change of copper contents and the binding of copper to proteins. There is a close relationship between these two kinds of diseases and copper. Here, we summarize the mechanisms of copper-related death, and the association between copper and diseases, to better figure out the influence of copper in cell death and diseases, thus advancing the clinical remedy of these diseases.

Copper exposure induces mitochondrial dysfunction and hepatotoxicity via the induction of oxidative stress and PERK/ATF4 -mediated endoplasmic reticulum stress

Copper is an essential trace element, and excessive exposure could result in hepatoxicity, however, the underlying molecular mechanisms remain incompletely understood. The present study is aimed to investigate the molecular mechanisms of copper sulfate (CuSO4) exposure-induced hepatoxicity both in vivo and in vitro. In vitro, HepG2 and L02 cells were exposed to various doses of CuSO4 for 24 h. Cell viability, ROS production, oxidative stress biomarkers, mitochondrial functions, ultrastructure, intracellular calcium (Ca2+) concentration, and the expression of proteins related to mitochondrial apoptosis and endoplasmic reticulum (ER) stress were assessed. In vivo, C57BL/6 mice were treated with CuSO4 at doses of 10 and 30 mg/kg BW/day and co-treated with 4-PBA at 100 mg/kg BW/day for 35 days. Subsequently, liver function, histopathological features, and protein expression were evaluated. Results found that exposure to CuSO4 at concentrations of 100-400 μM for 24 h significantly decreased the viabilities of HepG2 and L02 cells and it was in a dose-dependent manner. Additionally, CuSO4 exposure induced significant oxidative stress and mitochondrial dysfunction in HepG2 cells, which were partially ameliorated by the antioxidant N-acetylcysteine (NAC). Furthermore, CuSO4 exposure prominently triggered ER stress, as evidenced by the upregulation of GRP94, GRP78, phosphorylated forms of PERK and eIF2α, and CHOP proteins in livers of mice and HepG2 cells. NAC treatment significantly inhibited CuSO4 exposure -induced ER stress in HepG2 cells. Pharmacological inhibition of ER stress through co-treatment with 4-PBA and the PERK inhibitor GSK2606414, as well as genetic knockdown of ATF4, partially mitigated CuSO4-induced cytotoxicity in HepG2 cells by reducing mitochondrial dysfunction and inhibiting the mitochondrial apoptotic pathway. Moreover, 4-PBA treatment significantly attenuated CuSO4-induced caspase activation and hepatoxicity in mice. In conclusion, these results reveal that CuSO4-induced hepatotoxicity involves mitochondrial dysfunction and ER stress by activating oxidative stress induction and PERK/ATF4 pathway.

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.

Stachydrine hydrochloride protects the ischemic heart by ameliorating endoplasmic reticulum stress through a SERCA2a dependent way and maintaining intracellular Ca2+ homeostasis

This study aimed to explore the effects and mechanism of action of stachydrine hydrochloride (Sta) against myocardial infarction (MI) through sarcoplasmic/endoplasmic reticulum stress-related injury. The targets of Sta against MI were screened using network pharmacology. C57BL/6 J mice after MI were treated with saline, Sta (6 or 12 mg kg-1) for 2 weeks, and adult mouse and neonatal rat cardiomyocytes (AMCMs and NRCMs) were incubated with Sta (10-4-10-6 M) under normoxia or hypoxia for 2 or 12 h, respectively. Echocardiography, Evans blue, and 2,3,5-triphenyltetrazolium chloride (TTC) staining were used for morphological and functional analyses. Endoplasmic reticulum stress (ERS), unfolded protein reaction (UPR), apoptosis signals, cardiomyocyte contraction, and Ca2+ flux were detected using transmission electron microscopy (TEM), western blotting, immunofluorescence, and sarcomere and Fluo-4 tracing. The ingredient-disease-pathway-target network revealed targets of Sta against MI were related to apoptosis, Ca2+ homeostasis and ERS. Both dosages of Sta improved heart function, decreased infarction size, and potentially increased the survival rate. Sta directly alleviated ERS and UPR and elicited less apoptosis in the border myocardium and hypoxic NRCMs. Furthermore, Sta upregulated sarcoplasmic reticulum Ca2+-ATPase 2a (SERCA2a) in both ischaemic hearts and hypoxic NRCMs, accompanied by restored sarcomere shortening, resting intracellular Ca2+, and Ca2+ reuptake time constants (Tau) in Sta-treated hypoxic ARCMs. However, 2,5-di-t-butyl-1,4-benzohydroquinone (BHQ) (25 μM), a specific SERCA inhibitor, totally abolished the beneficial effect of Sta in hypoxic cardiomyocytes. Sta protects the heart from MI by upregulating SERCA2a to maintain intracellular Ca2+ homeostasis, thus alleviating ERS-induced apoptosis.

Redox regulation of UPR signalling and mitochondrial ER contact sites

Mitochondria and the endoplasmic reticulum (ER) have a synergistic relationship and are key regulatory hubs in maintaining cell homeostasis. Communication between these organelles is mediated by mitochondria ER contact sites (MERCS), allowing the exchange of material and information, modulating calcium homeostasis, redox signalling, lipid transfer and the regulation of mitochondrial dynamics. MERCS are dynamic structures that allow cells to respond to changes in the intracellular environment under normal homeostatic conditions, while their assembly/disassembly are affected by pathophysiological conditions such as ageing and disease. Disruption of protein folding in the ER lumen can activate the Unfolded Protein Response (UPR), promoting the remodelling of ER membranes and MERCS formation. The UPR stress receptor kinases PERK and IRE1, are located at or close to MERCS. UPR signalling can be adaptive or maladaptive, depending on whether the disruption in protein folding or ER stress is transient or sustained. Adaptive UPR signalling via MERCS can increase mitochondrial calcium import, metabolism and dynamics, while maladaptive UPR signalling can result in excessive calcium import and activation of apoptotic pathways. Targeting UPR signalling and the assembly of MERCS is an attractive therapeutic approach for a range of age-related conditions such as neurodegeneration and sarcopenia. This review highlights the emerging evidence related to the role of redox mediated UPR activation in orchestrating inter-organelle communication between the ER and mitochondria, and ultimately the determination of cell function and fate.

The mmu_circ_003062, hsa_circ_0075663/miR-490-3p/CACNA1H axis mediates apoptosis in renal tubular cells in association with endoplasmic reticulum stress following ischemic acute kidney injury

BACKGROUND

While recent studies have suggested a potential involvement of circRNAs in acute kidney injury (AKI) after ischemia, mmu_circ_003062 role is undetermined.

METHODS

The levels of mmu_circ_003062, miR-490-3p, CACNA1H, GRP78, CHOP and hsa_circ_0075663 were detected by Relative qPCR in Boston University mouse proximal tubule (BUMPT) cells, mouse kidneys, and human renal tubular epithelial (HK-2) cells. Moreover, the levels of hsa_circ_0075663 in serum and urine of patients with AKI following cardiopulmonary resuscitation (CPR) were detected by absolute quantitative PCR. Western blot was used to detect the relative expression of the protein. The function and regulatory mechanism of mmu_circ_003062 and hsa_circ_0075663 were investigated through a series of in vitro and in vivo experiments, including bioinformatic prediction, luciferase reporter assays, FISH, FCM, TUNEL staining, and H&E staining.

RESULTS

It was found that mmu_circ_003062, hsa_circ_0075663 mediated apoptosis after ischemia/reperfusion (I/R) by interaction with miR-490-3p to enhance CACNA1H expression, thereby leading to the upregulation of endoplasmic reticulum stress (ERS)-relevant proteins GRP78 and CHOP. Ultimately, mmu_circ_003062 downregulation significantly ameliorated ischemic AKI by modulating the miR-490-3p/CACNA1H/GRP78 and CHOP pathway. Furthermore, the plasma and urinary levels of hsa_circ_0075663 in patients with AKI following CPR were significantly higher than non-AKI patients, exhibited a strongly correlation with serum creatinine.

CONCLUSION

The involvement of mmu_circ_003062, hsa_circ_0075663/miR-490-3p/CACNA1H/GRP78 and CHOP axis is significant in the development of ischemic AKI. Moreover, hsa_circ_0075663 has potential as an early diagnostic biomarker.

The role of autophagy in mitigating osteoarthritis progression via regulation of chondrocyte apoptosis: A review

Osteoarthritis (OA) is the most prevalent chronic joint disease with an immense socioeconomic burden; however, no treatment has achieved complete success in effectively halting or reversing cartilage degradation, which is the central pathophysiological feature of OA. Chondrocytes loss or dysfunction is a significant contributing factor to the progressive cartilage deterioration as these sole resident cells have a crucial role to produce extracellular matrix proteins, thus maintaining cartilage structure and homeostasis. It has been previously suggested that death of chondrocytes occurring through apoptosis substantially contributes to cartilage degeneration. Although the occurrence of apoptosis in osteoarthritic cartilage and its correlation with cartilage degradation is evident, the causes of chondrocyte apoptosis leading to matrix loss are still not well-understood. Autophagy, an intracellular degradative mechanism that eliminates dysfunctional cytoplasmic components to aid cell survival in unfavourable conditions, is a potential therapeutic target to inhibit chondrocyte apoptosis and reduce OA severity. Despite accumulating evidence indicating significant cytoprotective effects of autophagy against chondrocyte apoptosis, the mechanistic link between autophagy and apoptosis in chondrocytes remains to be further explored. In this review, we summarize the relevant mechanistic events that perpetuate chondrocyte apoptosis and highlight the prominent role of autophagy in modulating these events to mitigate OA progression.

Endoplasmic reticulum stress and therapeutic strategies in metabolic, neurodegenerative diseases and cancer

The accumulation of unfolded or misfolded proteins within the endoplasmic reticulum (ER), due to genetic determinants and extrinsic environmental factors, leads to endoplasmic reticulum stress (ER stress). As ER stress ensues, the unfolded protein response (UPR), comprising three signaling pathways-inositol-requiring enzyme 1, protein kinase R-like endoplasmic reticulum kinase, and activating transcription factor 6 promptly activates to enhance the ER's protein-folding capacity and restore ER homeostasis. However, prolonged ER stress levels propels the UPR towards cellular demise and the subsequent inflammatory cascade, contributing to the development of human diseases, including cancer, neurodegenerative disorders, and diabetes. Notably, increased expression of all three UPR signaling pathways has been observed in these pathologies, and reduction in signaling molecule expression correlates with decreased proliferation of disease-associated target cells. Consequently, therapeutic strategies targeting ER stress-related interventions have attracted significant research interest. In this review, we elucidate the critical role of ER stress in cancer, metabolic, and neurodegenerative diseases, offering novel therapeutic approaches for these conditions.

The dual effect of endoplasmic reticulum stress in digestive system tumors and intervention of Chinese botanical drug extracts: a review

Endoplasmic reticulum (ER) homeostasis is essential for maintaining human health, and once imbalanced, it will trigger endoplasmic reticulum stress (ERS), which participates in the development of digestive system tumors and other diseases. ERS has dual effect on tumor cells, activating adaptive responses to promote survival or inducing apoptotic pathways to accelerate cell death of the tumor. Recent studies have demonstrated that Chinese botanical drug extracts can affect the tumor process of the digestive system by regulating ERS and exert anticancer effects. This article summarizes the dual effect of ERS in the process of digestive system tumors and the intervention of Chinese botanical drug extracts in recent years, as reference for the combined treatment of digestive system tumors with Chinese and modern medicine.

Zanthoxylum armatum DC fruit ethyl acetate extract site induced hepatotoxicity by activating endoplasmic reticulum stress and inhibiting autophagy in BRL-3A models

ETHNOPHARMACOLOGICAL RELEVANCE

Zanthoxylum armatum DC (Z. armatum) is renowned not only as a culinary spice but also as a staple in traditional ethnic medicine, predominantly in Southeast Asia and various other regions. Recent research has unveiled its multifaceted pharmacological properties, including anti-inflammatory, antibacterial, and toothache relief effects. Nonetheless, some studies have reported the potential toxicity of Z. armatum, emphasizing the need to further explore its toxicity mechanisms for safer application.

AIM OF THE STUDY

This study investigated the effect and mechanism of hepatotoxicity in BRL-3A cells induced by Z. armatum.

MATERIALS AND METHODS

The compounds of the ethyl acetate extract of Z. armatum (ZADC-EA) were identified by ultrahigh performance liquid chromatography coupled with quadrupole-orbitrap high resolution mass spectrometry (UPLC-Q-Orbitrap HRMS). The hepatotoxicity of the extract was evaluated by detecting cell viability, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) activity, and apoptosis. Endoplasmic reticulum stress, autophagy, and apoptosis were detected by Ad-mCherry-GFP-LC3B, flow cytometry, and Western blot to explore the mechanism of hepatotoxicity induced by ZADC-EA.

RESULTS

UPLC-Q-Orbitrap HRMS analysis revealed the presence of compounds belonging to flavonoids, terpenoids, and alkaloids. The IC50 value of ZADC-EA was 62.43 μg/mL, the cell viability of BRL-3A decreased in a time-dose dependent manner, and the levels of AST, ALT, and LDH were upregulated. In addition, ZADC-EA-induced increased expression of eIF2α-ATF4-CHOP pathway proteins, inhibited autophagy, and promoted apoptosis.

CONCLUSIONS

This study provides insights into the hepatotoxicity mechanisms of ZADC-EA on BRL-3A cells. It was found that ZADC-EA could induce endoplasmic reticulum stress and inhibit autophagy, then intensify apoptosis, and endoplasmic reticulum stress could exacerbate autophagy inhibition.

Endoplasmic reticulum stress exacerbates microplastics-induced toxicity in animal cells

Human and animal exposure to microplastics (MPs) contained in food is inevitable because of their widespread existence in the environment. Nevertheless, MPs toxicity studies in ruminants often lack attention. Here, we assessed the cytotoxicity of polystyrene microplastics (PS MPs) on goat mammary epithelial cells (GMECs). Compared to controls, PS MPs treatment significantly reduced cell viability, altered cell morphology and disrupted organelle integrity. Detection of membrane potential and reactive oxygen species (ROS) suggested that PS MPs induced mitochondrial dysfunction and oxidative stress. Further transcriptome analysis also confirmed alterations in these pathways. In addition, several genes related to endoplasmic reticulum (ER) homeostasis were significantly regulated in the transcriptional profile. Subsequent experiments confirmed that PS MPs induce ER stress via the PERK/eIF2α/CHOP pathway, accompanied by intracellular Ca2+ overload. Meanwhile, downstream activation of the Bax/Bcl-2 pathway and caspase cascade released apoptotic signals, which led to apoptosis in GMECs. Interestingly, the addition of PERK inhibitor (ISRIB) attenuated PS MPs-induced ER stress and apoptosis, which suggests that ER stress may exacerbate PS MPs-induced cytotoxicity. This work reveals the impact of MPs on mammalian cytotoxicity, enriches the mechanisms for the toxicity of MPs, and provides insight for further assessment of the risk of MPs in food.

Patulin induces ROS-dependent cardiac cell toxicity by inducing DNA damage and activating endoplasmic reticulum stress apoptotic pathway

Patulin (PAT) is one of the mycotoxins commonly found in agricultural products and fruits, and has obvious toxic effects on animals and humans. PAT has been found to cause myocardial toxicity and oxidative damage, but the mechanism of myocardial toxicity remained to be elucidated. We investigated the toxic effects and potential mechanisms of PAT on human cardiomyocytes and explored the effects of reactive oxygen species (ROS) on them. The study showed that treatment with PAT for 24 h decreased cell viability and superoxide dismutase (SOD) activity, and increased ROS and lactate dehydrogenase (LDH) levels. Moreover, in addition to detecting increased γ-H2AX expression and observing nuclear damage, the comet assay also showed increased DNA tail distance in the PAT-treated group, followed by an increase in phosphorylation of the p53 protein and p21 protein expression, and a decrease in CDK1 and Cyclin B1 protein expression, and G2/M phase arrest. In addition, PAT induced endoplasmic reticulum stress (ERS) and induced apoptosis, as evidenced by Ca2+ increase, ER enlargement and swelling, and upregulation of ERS-related genes and proteins expression, and increased expression of three apoptotic pathway proteins under ERS, including CHOP, JNK, and caspase-12. Meanwhile, N-acetylcysteine (NAC, a ROS scavenger) reversed the negative effects of PAT treatment on cells. These results clarify that excessive ROS production by PAT-treated AC16 cells not only causes DNA damage, leading to cell cycle arrest, but also causes ERS, which triggers apoptotic pathways to cause apoptosis.

Cuproptosis and physical training

Copper is an essential element in the human body, involved in many physiological and metabolic functions, including coagulation, oxidative metabolism, and hormone production. The maintenance of copper homeostasis within cells is a complex procedure that is intrinsically controlled by a multitude of intricate mechanisms. Disorders of copper homeostasis encompass a wide range of pathological conditions, including degenerative neurological diseases, metabolic disorders, cardio-cerebrovascular diseases, and tumors. Cuproptosis, a recently identified non-apoptotic mode of cell death mode, is characterized by copper dependence and the regulation of mitochondrial respiration. Cuproptosis represents a novel form of cell death distinct from the previously described modes, including apoptosis, necrosis, pyroptosis, and ferroptosis. Excess copper has been shown to induce cuproptosis by stimulating protein toxic stress responses via copper-dependent abnormal oligomerization of lipoylation proteins within the tricarboxylic acid cycle and the subsequent reduction of iron-sulfur cluster protein levels. Ferredoxin1 facilitates the lipoacylation of dihydrolipoyl transacetylase, which in turn degrades iron-sulfur cluster proteins by reducing Cu2+ to Cu+, thereby inducing cell death. Furthermore, copper homeostasis is regulated by the copper transporter, and disturbances in this homeostasis result in cuproptosis. Current evidence suggests that cuproptosis plays an important role in the onset and development of several cardiovascular diseases. Copper-chelating agents, including ammonium tetrathiomolybdate (VI) and DL-penicillamine, have been shown to facilitate the alleviation of cardiovascular disease by inhibiting cuproptosis. It is hypothesized that oxidative phosphorylation inhibitors such as physical training may inhibit cuproptosis by inhibiting the protein stress response. In conclusion, the implementation of physical training may be a viable strategy to reducte the incidence of cuproptosis.

The Upstream 1350~1250 Nucleotide Sequences of the Human ENDOU-1 Gene Contain Critical Cis-Elements Responsible for Upregulating Its Transcription during ER Stress

ENDOU-1 encodes an endoribonuclease that overcomes the inhibitory upstream open reading frame (uORF)-trap at 5'-untranslated region (UTR) of the CHOP transcript, allowing the downstream coding sequence of CHOP be translated during endoplasmic reticulum (ER) stress. However, transcriptional control of ENDOU-1 remains enigmatic. To address this, we cloned an upstream 2.1 kb (-2055~+77 bp) of human ENDOU-1 (pE2.1p) fused with reporter luciferase (luc) cDNA. The promoter strength driven by pE2.1p was significantly upregulated in both pE2.1p-transfected cells and pE2.1p-injected zebrafish embryos treated with stress inducers. Comparing the luc activities driven by pE2.1p and -1125~+77 (pE1.2p) segments, we revealed that cis-elements located at the -2055~-1125 segment might play a critical role in ENDOU-1 upregulation during ER stress. Since bioinformatics analysis predicted many cis-elements clustered at the -1850~-1250, we further deconstructed this segment to generate pE2.1p-based derivatives lacking -1850~-1750, -1749~-1650, -1649~-1486, -1485~-1350 or -1350~-1250 segments. Quantification of promoter activities driven by these five internal deletion plasmids suggested a repressor binding element within the -1649~-1486 and an activator binding element within the -1350~-1250. Since luc activities driven by the -1649~-1486 were not significantly different between normal and stress conditions, we herein propose that the stress-inducible activator bound at the -1350~-1250 segment makes a major contribution to the increased expression of human ENDOU-1 upon ER stresses.

Quercetin alleviates cadmium-induced BRL-3A cell apoptosis by inhibiting oxidative stress and the PERK/IRE1α/ATF6 signaling pathway

Cadmium (Cd) is a highly toxic environmental pollutant. The liver is an important metabolic organ in the body and is susceptible to Cd toxicity attacks. Quercetin (Que) is a flavonoid compound with pharmacological activities of scavenging free radicals and antioxidant activity. Previous studies have shown that Que can alleviate Cd caused hepatocyte apoptosis in rats, but the specific mechanism remains unclear. To explore the specific mechanism, we established a model of Cd toxicity and Que rescue in BRL-3A cells and used 4-phenylbutyrate (4-PBA), an endoplasmic reticulum stress (ERS) inhibitor, as positive control. Set up a control group, Cd treatment group, Cd and Que co treatment group, Que treatment group, Cd and 4-PBA co treatment group, and 4-PBA treatment group. Cell Counting Kit-8 (CCK-8) method was employed to measure cell viability. Fluorescence staining was applied to observe cell apoptosis. Flow cytometry was performed to detect reactive oxygen species levels. Real-time quantitative polymerase chain reaction (qRT-PCR) and Western blot method was adopted to detect the mRNA and protein expression levels of ERS and apoptosis-related genes. The results showed that compared with the control group, the Cd treated group showed a significant decrease in cell viability (P < 0.01), an increase in intracellular ROS levels, and apoptosis. The mRNA and protein expression levels of ERS and apoptosis related factors such as GRP78, IRE1α, XBP1, ATF6, Caspase-12, Caspase-3 and Bax in the cells were significantly increased (P < 0.01), while the mRNA and protein expression levels of Bcl-2 were significantly reduced (P < 0.01). Compared with the Cd treatment group, the Cd and Que co treatment group and the Cd and 4-PBA co treatment group showed a significant increase in cell viability (P < 0.01), a decrease in intracellular ROS levels, a decrease in cell apoptosis, and a significant decrease in the expression levels of ERS and apoptosis related factors mRNA and protein (P < 0.01), as well as a significant increase in Bcl-2 mRNA and protein expression (P < 0.01). We confirmed that Que could alleviate the apoptosis caused by Cd in BRL-3A cells, and the effects of Que were similar to those of ERS inhibitor.

Exposure to copper induces endoplasmic reticulum (ER) stress-mediated apoptosis in chicken (Gallus gallus) myocardium

Copper (Cu), an omnipresent environmental pollutant, can cause potential harm to the public and ecosystems. In order to study the cardiotoxicity caused by Cu, molecular biology techniques were used to analyze the effect of Cu on ER stress-mediated cardiac apoptosis. In vivo investigation, 240 1-day-old chickens were fed with Cu (11, 110, 220, and 330 mg/kg) diet for 7 weeks. The consequence showed that high-Cu can induce ER stress and apoptosis in heart tissue. The vitro experiments, the Cu treatment for 24 h could provoke ultrastructural damage and upregulate the apoptosis rate. Meanwhile, GRP78, GRP94, eIF2α, ATF6, XBP1, CHOP, Bax, Bak1, Bcl2, Caspase-12 and Caspase-3 genes levels, and GRP78, GRP94 and Caspase-3 proteins levels were increased, which indicated that ER stress and apoptosis in cardiomyocytes. But the mRNA level of Bcl2 were decreased after Cu exposure. Conversely, Cu-induced ER stress-mediated apoptosis can be alleviated by treatment with 4-PBA. These findings generally showed that Cu exposure can contribute to ER stress-mediated apoptosis in chicken myocardium, which clarifies the important mechanism link between ER stress and apoptosis, and provides a new perspective for Cu toxicology.

Andrographolide contributes to the attenuation of cardiac hypertrophy by suppressing endoplasmic reticulum stress

CONTEXT

Andrographolide (Andr) is a bioactive Andr diterpenoid extracted from herbaceous Andrographis paniculata (Burm. F.) Wall. ex Nees (Acanthaceae). Andr can relieve cardiac dysfunction in mice by inhibiting the mitogen-activated protein kinases (MAPK) pathway.

OBJECTIVE

This study investigates the efficacy and underlying mechanism of Andr on cardiac hypertrophy in mice.

MATERIALS AND METHODS

Male C57 mice (20-25 g, 6-8 weeks) were divided into four groups (n = 10 mice/group) as sham group (sham operation), transverse aortic constriction (TAC) model group, TAC + Andr 100 mg/kg group and TAC + Andr 200 mg/kg group. Andr groups were given intragastric administration of Andr (100 and 200 mg/kg) once a day for 14 consecutive days. An in vitro hypertrophy model was established by adding 1 μM of Ang II to H9c2 cells for 48 h induction.

RESULTS

In TAC-mice, Andr improved echocardiographic indices [reduced LVESD (30.4% or 37.1%) and LVEDD (24.8% or 26.4%), increased EF (22.9% or 42.6%) and FS (25.4% or 52.2%)], reduced BNP (11.5% or 23.6%) and Ang II levels (10.3% or 32.8%), attenuates cardiac fibrosis and reduces cardiac cell apoptosis in TAC mice. In vitro, Andr attenuated cardiomyocyte hypertrophy and decreased the protein expression of GRP78 (67.8%), GRP94 (47.6%), p-PERK (44.9%) and CHOP (66.8%) in Ang-II-induced H9c2 cells and reversed after endoplasmic reticulum (ER) stress agonist Tunicamycin (TN) treatment.

DISCUSSION AND CONCLUSIONS

Andr was found to be an anti-hypertrophic regulator, which could attenuate cardiac hypertrophy by suppressing ER stress. It may be a new therapeutic drug for cardiac hypertrophy.

Endoplasmic reticulum stress in the pathogenesis of alcoholic liver disease

The endoplasmic reticulum (ER) plays a pivotal role in protein synthesis, folding, and modification. Under stress conditions such as oxidative stress and inflammation, the ER can become overwhelmed, leading to an accumulation of misfolded proteins and ensuing ER stress. This triggers the unfolded protein response (UPR) designed to restore ER homeostasis. Alcoholic liver disease (ALD), a spectrum disorder resulting from chronic alcohol consumption, encompasses conditions from fatty liver and alcoholic hepatitis to cirrhosis. Metabolites of alcohol can incite oxidative stress and inflammation in hepatic cells, instigating ER stress. Prolonged alcohol exposure further disrupts protein homeostasis, exacerbating ER stress which can lead to irreversible hepatocellular damage and ALD progression. Elucidating the contribution of ER stress to ALD pathogenesis may pave the way for innovative therapeutic interventions. This review delves into ER stress, its basic signaling pathways, and its role in the alcoholic liver injury.

Unfolded Protein Response Signaling in Liver Disorders: A 2023 Updated Review

Endoplasmic reticulum (ER) is the site for synthesis and folding of secreted and transmembrane proteins. Disturbance in the functioning of ER leads to the accumulation of unfolded and misfolded proteins, which finally activate the unfolded protein response (UPR) signaling. The three branches of UPR-IRE1 (Inositol requiring enzyme 1), PERK (Protein kinase RNA-activated (PKR)-like ER kinase), and ATF6 (Activating transcription factor 6)-modulate the gene expression pattern through increased expression of chaperones and restore ER homeostasis by enhancing ER protein folding capacity. The liver is a central organ which performs a variety of functions which help in maintaining the overall well-being of our body. The liver plays many roles in cellular physiology, blood homeostasis, and detoxification, and is the main site at which protein synthesis occurs. Disturbance in ER homeostasis is triggered by calcium level imbalance, change in redox status, viral infection, and so on. ER dysfunction and subsequent UPR signaling participate in various hepatic disorders like metabolic (dysfunction) associated fatty liver disease, liver cancer, viral hepatitis, and cholestasis. The exact role of ER stress and UPR signaling in various liver diseases is not fully understood and needs further investigation. Targeting UPR signaling with drugs is the subject of intensive research for therapeutic use in liver diseases. The present review summarizes the role of UPR signaling in liver disorders and describes why UPR regulators are promising therapeutic targets.

Copper-instigated modulatory cell mortality mechanisms and progress in oncological treatment investigations

Copper, a transition metal, serves as an essential co-factor in numerous enzymatic active sites and constitutes a vital trace element in the human body, participating in crucial life-sustaining activities such as energy metabolism, antioxidation, coagulation, neurotransmitter synthesis, iron metabolism, and tetramer deposition. Maintaining the equilibrium of copper ions within biological systems is of paramount importance in the prevention of atherosclerosis and associated cardiovascular diseases. Copper induces cellular demise through diverse mechanisms, encompassing reactive oxygen species responses, apoptosis, necrosis, pyroptosis, and mitochondrial dysfunction. Recent research has identified and dubbed a novel regulatory cell death modality-"cuprotosis"-wherein copper ions bind to acylated proteins in the tricarboxylic acid cycle of mitochondrial respiration, resulting in protein aggregation, subsequent downregulation of iron-sulfur cluster protein expression, induction of proteotoxic stress, and eventual cell death. Scholars have synthesized copper complexes by combining copper ions with various ligands, exploring their significance and applications in cancer therapy. This review comprehensively examines the multiple pathways of copper metabolism, copper-induced regulatory cell death, and the current status of copper complexes in cancer treatment.

Copper induced intestinal inflammation response through oxidative stress induced endoplasmic reticulum stress in Takifugu fasciatus

Copper (Cu) pollution in aquaculture water has seriously threatened the healthy and sustainable development of the aquaculture industry. Recently, many researchers have studied the toxic effects of Cu exposure on fish. However, the relationship between endoplasmic reticulum stress (ERS) and the inflammatory response, as well as its possible mechanisms, remain unclear. Particularly, information related to fish intestines must be expanded. Our study initially investigated the mechanisms underlying intestinal toxicity and inflammation resulting from Cu-induced ERS in vivo and in vitro in Takifugu fasciatus. In vivo study, T. fasciatus were treated with different concentrations (control, 20, and 100 µg/L) of Cu exposure for 28 days, causing intestinal oxidative stress, ERS, inflammatory responses, and histopathological and ultrastructural damage. Transcriptomic data further showed that Cu exposure caused ERS, as well as inflammatory responses, in the intestinal tracts of T. fasciatus. In vitro experiments on the intestinal cells of T. fasciatus showed that Cu exposure treatment (7.5 µg/mL) for 24 h induced ERS and increased mitochondrial numbers and inflammatory responses. In contrast, the addition of 4-phenylbutyric acid (4-PBA) alleviated ERS and inflammatory response in the Cu-exposed group. Furthermore, the reactive oxygen species (ROS) inhibitor, N-Acetyl-l-cysteine (NAC), effectively alleviated Cu-induced ERS. In conclusion, our in vivo and in vitro studies have confirmed that oxidative stress triggers the ERS pathway, which is involved in the intestinal inflammatory response. Our study provides new insights into the relationship among Cu-induced oxidative stress, ERS, and inflammatory responses in fish, as well as for the healthy culture of fish in aqueous environments.

Copper in cancer: from limiting nutrient to therapeutic target

As an essential nutrient, copper's redox properties are both beneficial and toxic to cells. Therefore, leveraging the characteristics of copper-dependent diseases or using copper toxicity to treat copper-sensitive diseases may offer new strategies for specific disease treatments. In particular, copper concentration is typically higher in cancer cells, making copper a critical limiting nutrient for cancer cell growth and proliferation. Hence, intervening in copper metabolism specific to cancer cells may become a potential tumor treatment strategy, directly impacting tumor growth and metastasis. In this review, we discuss the metabolism of copper in the body and summarize research progress on the role of copper in promoting tumor cell growth or inducing programmed cell death in tumor cells. Additionally, we elucidate the role of copper-related drugs in cancer treatment, intending to provide new perspectives for cancer treatment.

The molecular mechanisms of cuproptosis and its relevance to cardiovascular disease

Recently, cuproptosis has been demonstrated to be a new non-apototic cell death mode that is characterized by copper dependence and the regulation of mitochondrial respiration. Cuproptosis is distinct from known cell death modes such as apoptosis, necrosis, pyroptosis, or ferroptosis. Excessive copper induces cuproptosis by promoting protein toxic stress reactions via copper-dependent anomalous oligomerization of lipoylation proteins in the tricarboxylic acid (TCA) cycle and reducing iron-sulfur cluster protein levels. Ferredoxin1 (FDX1) promotes dihydrolipoyl transacetylase (DLAT) lipoacylation and abates iron-sulfur cluster proteins by reducing Cu²⁺ to Cu⁺, inducing cell death. Copper homeostasis depends on the copper transporter, and disturbances to this homeostasis cause cuproptosis. Recent evidence has shown that cuproptosis plays a significant role in the occurrence and development of many cardiovascular diseases, such as myocardial ischemia/reperfusion (I/R) injury, heart failure, atherosclerosis, and arrhythmias. Copper chelators, such as ammonium tetrathiomolybdate(VI) and DL-Penicillamine, may ease the above cardiovascular diseases by inhibiting the cuproptosis pathway. Oxidative phosphorylation inhibitors may inhibit cuproptosis by inhibiting protein stress response. In conclusion, cuproptosis plays an essential role in cardiovascular disease pathogenesis. Inhibition of cardiovascular cuproptosis is expected to become a potential treatment. Here, we will thoroughly review the molecular mechanisms involved in cuproptosis and its significance in cardiovascular disease.

Interrelation between Programmed Cell Death and Immunogenic Cell Death: Take Antitumor Nanodrug as an Example

Programmed cell death (PCD, mainly including apoptosis, necrosis, ferroptosis, pyroptosis, and autophagy) and immunogenic cell death (ICD), as important cell death mechanisms, are widely reported in cancer therapy, and understanding the relationship between the two is significant for clinical tumor treatments. Considering that vast nanodrugs are developed to induce tumor PCD and ICD simultaneously, in this review, the interrelationship between PCD and ICD is described using nanomedicines as examples. First, an overview of PCD patterns and focus on the morphological differences and interconnections among them are provided. Then the interrelationship between apoptosis and ICD in terms of endoplasmic reticulum stress is described by introducing various cancer treatments and the recent developments of nanomedicines with inducible immunogenicity. Next, the crosstalk between non-apoptotic (including necrosis, ferroptosis, pyroptosis, and autophagy) signaling pathways and ICD is introduced and their relationship through various nanomedicines as examples is further illustrated. Finally, the relationship between PCD and ICD and its application prospects in the development of new ICD nanomaterials are summarized. This review is believed to deepen the understanding of the relationship between PCD and ICD, extend the biomedical applications of various nanodrugs, and promote the progress of clinical tumor therapy.

Physcion prevents high-fat diet-induced endothelial dysfunction by inhibiting oxidative stress and endoplasmic reticulum stress pathways

High-fat diet (HFD)-induced obesity leads endothelial dysfunction and contributes to cardiovascular diseases. Palmitic acid (PA), a free fatty acid, is the main component of dietary saturated fat. Physcion, a chemical ingredient from Rhubarb, has been shown anti-hypertensive, anti-bacteria, and anti-tumor properties. However, the effects of physcion on endothelial dysfunction under HFD-induced obesity have not been reported. The purpose of the present study was to define the protective effect of physcion on HFD-induced endothelial dysfunction and its mechanisms involved. Obesity rat model was induced by HFD for 12 weeks. A rat thoracic aortic ring model was used to investigate the effects of physcion on HFD-induced impairment of vasorelaxation. Endothelial cell injury model was constructed in human umbilical vein endothelial cells (HUVECs) by treating with PA (0.25 mM) for 24 h. The results revealed that physcion reduced body weight and the levels of plasma TG, prevented impairment of endothelium-dependent relaxation in HFD-fed rats. In PA-injured HUVECs, physcion inhibited impaired viability, apoptosis and inflammation. Physcion also suppressed PA-induced both oxidative stress and ER stress in HUVECs. Furthermore, physcion increased PA-induced decrease in the activation of eNOS/Nrf2 signaling in HUVECs. These findings suggest that physcion has a significant beneficial effect on regulating HFD-induced endothelial dysfunction, which may be related to the inhibition of oxidative stress and ER stress through activation of eNOS/Nrf2 signaling pathway.

Exposure to copper activates mitophagy and endoplasmic reticulum stress-mediated apoptosis in chicken (Gallus gallus) cerebrum

A large amount of copper (Cu) used in production activities can lead to the enrichment of Cu in the environment, which can cause toxicity to animals. However, the toxicity mechanism of Cu on the cerebrum is still uncertain. Hence, a total of 240 chickens were separated into four groups in this study to reveal the potential connection between mitophagy and endoplasmic reticulum (ER) stress-mediated apoptosis in the chicken cerebrum in the case of excess Cu exposure. The cu exposure situation was simulated by diets containing various levels of copper (11 mg/kg, control group; 110 mg/kg, group I; 220 mg/kg, group II and 330 mg/kg, group III) for 49 days. The results of histology showed that vacuolar degeneration was observed in the treated groups, and the mitochondria swell and autophagosomes formation were found under excess Cu treatment. Additionally, the expression of mitophagy (PINK1, Parkin, LC3I, LC3II and p62) and ER stress (GRP78, PERK, ATF6, IRE1α, XBP1, CHOP, and JNK) indexes were significantly upregulated under excess Cu exposure. Furthermore, the mRNA and protein expression of Bcl-2 were decreased, while Bak1, Bax, Caspase12, and Caspase3 were increased compared to the control group. In summary, this study demonstrated that an overdose of Cu could induce mitophagy and ER stress-mediated apoptosis in the chicken cerebrum. These findings revealed an important potential connection between Cu toxicity and cerebrum damage, which provided a new insight into Cu neurotoxicity.

Chronic hypoxia and Cu2+ exposure induce gill remodeling of largemouth bass through endoplasmic reticulum stress, mitochondrial damage and apoptosis

Hypoxia and Cu²⁺ pollution often occur simultaneously in aquatic ecosystems and jointly affect physiology of fish. As the respiratory and ion exchange tissue of fish, how gill responds to the stress induced by these two abiotic environmental factors is still unclear. We have conducted a study by exposing largemouth bass (Micropterus salmoides) to hypoxia (2.0 mg·L^-1) and/or Cu²⁺ (0.5 mg·L^-1) for 28 days to answer this question. We subsequently studied respiratory rate, Cu²⁺ transport, endoplasmic reticulum (ER) stress, mitochondrial damage, and morphology in gill tissue on day 7, 14, 21 and 28. We found that hypoxia exposure increased the respiratory rate of largemouth bass, reflecting the response of largemouth bass to cope with hypoxia. Of note, Cu²⁺ entered gill by specifically binding to CTR1 and its accumulation dramatically in gill disrupted the response of largemouth bass to hypoxia. Hypoxia and/or Cu²⁺ exposure led to ER stress and mitochondrial damage in gills of largemouth bass. ER stress and mitochondrial damage induced apoptosis by activating caspase-8 and caspase-9 signaling pathways, respectively. Apoptosis induced by hypoxia and Cu²⁺ exposure had a positive and synergistic effect on gill remodeling by reducing interlamellar cell masses. In addition, Cu²⁺ exposure induced hypoxia-like remodeling to gill morphology through mechanisms similar to hypoxia exposure. Most of gene expression changed mainly within 21 days and recovered to the control level on day 28, reflecting the acclimation of largemouth bass to hypoxia and/or Cu²⁺ exposure at gene expression level. Overall, our research suggests that chronic hypoxia and Cu²⁺ exposure could induce gill remodeling of largemouth bass through ER stress, mitochondrial damage and apoptosis. The outcomes could provide an insight for fish environmental adaptation and environmental toxicology.

The Dysregulation of Inflammatory Pathways Triggered by Copper Exposure

Copper (Cu) is an essential micronutrient for both human and animals. However, excessive intake of copper will cause damage to organs and cells. Inflammation is a biological response that can be induced by various factors such as pathogens, damaged cells, and toxic compounds. Dysregulation of inflammatory responses are closely related to many chronic diseases. Recently, Cu toxicological and inflammatory effects have been investigated in various animal models and cells. In this review, we summarized the known effect of Cu on inflammatory responses and sum up the molecular mechanism of Cu-regulated inflammation. Excessive Cu exposure can modulate a huge number of cytokines in both directions, increase and/or decrease through a variety of molecular and cellular signaling pathways including nuclear factor kappa-B (NF-κB) pathway, mitogen-activated protein kinase (MAPKs) pathway, JAK-STAT (Janus Kinase- signal transducer and activator of transcription) pathway, and NOD-like receptor protein 3 (NLRP3) inflammasome. Underlying the molecular mechanism of Cu-regulated inflammation could help further understanding copper toxicology and copper-associated diseases.

Endoplasmic reticulum stress-mediated cell death in liver injury

The endoplasmic reticulum is an important intracellular organelle that plays an important role in maintaining cellular homeostasis. Endoplasmic reticulum stress (ERS) and unfolded protein response (UPR) are induced when the body is exposed to adverse external stimuli. It has been established that ERS can induce different cell death modes, including autophagy, apoptosis, ferroptosis, and pyroptosis, through three major transmembrane receptors on the ER membrane, including inositol requirement enzyme 1α, protein kinase-like endoplasmic reticulum kinase and activating transcription factor 6. These different modes of cell death play an important role in the occurrence and development of various diseases, such as neurodegenerative diseases, inflammation, metabolic diseases, and liver injury. As the largest metabolic organ, the liver is rich in enzymes, carries out different functions such as metabolism and secretion, and is the body's main site of protein synthesis. Accordingly, a well-developed endoplasmic reticulum system is present in hepatocytes to help the liver perform its physiological functions. Current evidence suggests that ERS is closely related to different stages of liver injury, and the death of hepatocytes caused by ERS may be key in liver injury. In addition, an increasing body of evidence suggests that modulating ERS has great potential for treating the liver injury. This article provided a comprehensive overview of the relationship between ERS and four types of cell death. Moreover, we discussed the mechanism of ERS and UPR in different liver injuries and their potential therapeutic strategies.