Zinc transporter ZIP7 is a novel determinant of ferroptosis

Inflammatory immunity and bacteriological perspectives: A new direction for copper treatment of sepsis

Copper is an essential trace element for all aerobic organisms because of its unique biological functions. In recent years, researchers have discovered that copper can induce cell death through various regulatory mechanisms, thereby inducing inflammation. Efforts have also been made to alter the chemical structure of copper to achieve either anticancer or anti-inflammatory effects. The copper ion can exhibit bactericidal effects by interfering with the integrity of the cell membrane and promoting oxidative stress. Sepsis is a systemic inflammatory response caused by infection. Some studies have revealed that copper is involved in the pathophysiological process of sepsis and is closely related to its prognosis. During the infection of sepsis, the body may enhance the antimicrobial effect by increasing the release of copper. However, to avoid copper poisoning, all organisms have evolved copper resistance genes. Therefore, further analysis of the complex relationship between copper and bacteria may provide new ideas and research directions for the treatment of sepsis.

Ferroptosis as a promising targeted therapy for triple negative breast cancer

PURPOSE

Triple negative breast cancer (TNBC) is a challenging subtype characterized by the absence of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression. Standard treatment options are limited, and approximately 45% of patients develop distant metastasis. Ferroptosis, a regulated form of cell death triggered by iron-dependent lipid peroxidation and oxidative stress, has emerged as a potential targeted therapy for TNBC.

METHODS

This study utilizes a multifaceted approach to investigate the induction of ferroptosis as a therapeutic strategy for TNBC. It explores metabolic alterations, redox imbalance, and oncogenic signaling pathways to understand their roles in inducing ferroptosis, characterized by lipid peroxidation, reactive oxygen species (ROS) generation, and altered cellular morphology. Critical pathways such as Xc-/GSH/GPX4, ACSL4/LPCAT3, and nuclear factor erythroid 2-related factor 2 (NRF2) are examined for their regulatory roles in ferroptosis and their potential dysregulation contributing to cancer cell survival and resistance.

RESULTS

Inhibiting ferroptosis has been shown to inhibit tumor growth, enhance the efficacy of conventional therapies, and overcome drug resistance in TNBC. Lipophilic antioxidants, GPX4 inhibitors, and inhibitors of the Xc- system have been demonstrated to be potential ferroptosis inducers. Additionally, targeting the NRF2 pathway and exploring other ferroptosis regulators, such as ferroptosis suppressor protein 1 (FSP1), and the PERK-eIF2α-ATF4-CHOP pathway, may offer novel therapeutic avenues.

CONCLUSION

Further research is needed to understand the mechanisms, optimize therapeutic strategies, and evaluate the safety and efficacy of ferroptosis-targeted therapies in TNBC treatment. Overall, targeting ferroptosis represents a promising approach to improving treatment outcomes and overcoming the challenges posed by TNBC.

From ferroptosis to cuproptosis, and calcicoptosis, to find more novel metals-mediated distinct form of regulated cell death

Regulated cell death (RCD), also known as programmed cell death (PCD), plays a critical role in various biological processes, such as tissue injury/repair, development, and homeostasis. Dysregulation of RCD pathways can lead to the development of many human diseases, such as cancer, neurodegenerative disorders, and cardiovascular diseases. Maintaining proper metal ion homeostasis is critical for human health. However, imbalances in metal levels within cells can result in cytotoxicity and cell death, leading to a variety of diseases and health problems. In recent years, new types of metal overload-induced cell death have been identified, including ferroptosis, cuproptosis, and calcicoptosis. This has prompted us to examine the three defined metal-dependent cell death types, and discuss other metals-induced ferroptosis, cuproptosis, and disrupted Ca2+ homeostasis, as well as the roles of Zn2+ in metals' homeostasis and related RCD. We have reviewed the connection between metals-induced RCD and various diseases, as well as the underlying mechanisms. We believe that further research in this area will lead to the discovery of novel types of metal-dependent RCD, a better understanding of the underlying mechanisms, and the development of new therapeutic strategies for human diseases.

Machine learning-based identification and immune characterization of ferroptosis-related molecular clusters in osteoarthritis and validation

Osteoarthritis (OA), a degenerative joint disease, involves synovial inflammation, subchondral bone erosion, and cartilage degeneration. Ferroptosis, a regulated non-apoptotic programmed cell death, is associated with various diseases. This study investigates ferroptosis-related molecular subtypes in OA to comprehend underlying mechanisms. The Gene Expression Omnibus datasets GSE206848, GSE55457, GSE55235, GSE77298 and GSE82107 were used utilized. Unsupervised clustering identified the ferroptosis-related gene (FRG) subtypes, and their immune characteristics were assessed. FRG signatures were derived using LASSO and SVM-RFE algorithms, forming models to evaluate OA's ferroptosis-related immune features. Three FRG clusters were found to be immunologically heterogeneous, with cluster 1 displaying robust immune response. Models identified nine key signature genes via algorithms, demonstrating strong diagnostic and prognostic performance. Finally, qRT-PCR and Western blot validated these genes, offering consistent results. In addition, some of these genes may have implications as new therapeutic targets and can be used to guide clinical applications.

ZIP transporters-regulated Zn2+ homeostasis: A novel determinant of human diseases

As an essential trace element for organisms, zinc participates in various physiological processes, such as RNA transcription, DNA replication, cell proliferation, and cell differentiation. The destruction of zinc homeostasis is associated with various diseases. Zinc homeostasis is controlled by the cooperative action of zinc transporter proteins that are responsible for the influx and efflux of zinc. Zinc transporter proteins are mainly categorized into two families: Zrt/Irt-like protein (SLC39A/ZIP) family and zinc transporter (SLC30A/ZNT) family. ZIP transporters contain 14 members, namely ZIP1-14, which can be further divided into four subfamilies. Currently, ZIP transporters-regulated zinc homeostasis is one of the research hotspots. Cumulative evidence suggests that ZIP transporters-regulated zinc homeostasis may cause physiological dysfunction and contribute to the onset and progression of diverse diseases, such as cancers, neurological diseases, and cardiovascular diseases. In this review, we initially discuss the structure and distribution of ZIP transporters. Furthermore, we comprehensively review the latest research progress of ZIP transporters-regulated zinc homeostasis in diseases, providing a new perspective into new therapeutic targets for treating related diseases.

Examining the Pathogenesis of MAFLD and the Medicinal Properties of Natural Products from a Metabolic Perspective

Metabolic-associated fatty liver disease (MAFLD), characterized primarily by hepatic steatosis, has become the most prevalent liver disease worldwide, affecting approximately two-fifths of the global population. The pathogenesis of MAFLD is extremely complex, and to date, there are no approved therapeutic drugs for clinical use. Considerable evidence indicates that various metabolic disorders play a pivotal role in the progression of MAFLD, including lipids, carbohydrates, amino acids, and micronutrients. In recent years, the medicinal properties of natural products have attracted widespread attention, and numerous studies have reported their efficacy in ameliorating metabolic disorders and subsequently alleviating MAFLD. This review aims to summarize the metabolic-associated pathological mechanisms of MAFLD, as well as the natural products that regulate metabolic pathways to alleviate MAFLD.

FNDC5/irisin ameliorates bone loss of type 1 diabetes by suppressing endoplasmic reticulum stress‑mediated ferroptosis

BACKGROUND

Ferroptosis is known to play a crucial role in diabetic osteopathy. However, key genes and molecular mechanisms remain largely unclear. This study aimed to identify a crucial ferroptosis-related differentially expressed gene (FR-DEG) in diabetic osteopathy and investigate its potential mechanism.

METHODS

We identified fibronectin type III domain-containing protein 5 (FNDC5)/irisin as an essential FR-DEG in diabetic osteopathy using the Ferroptosis Database (FerrDb) and GSE189112 dataset. Initially, a diabetic mouse model was induced by intraperitoneal injection of streptozotocin (STZ), followed by intraperitoneal injection of irisin. MC3T3-E1 cells treated with high glucose (HG) were used as an in vitro model. FNDC5 overexpression plasmid was used to explore underlying mechanisms in vitro experiments. Femurs were collected for micro-CT scan, histomorphometry, and immunohistochemical analysis. Peripheral serum was collected for ELISA analysis. Cell viability was assessed using a CCK-8 kit. The levels of glutathione (GSH), malondialdehyde (MDA), iron, reactive oxygen species (ROS), and lipid ROS were detected by the corresponding kits. Mitochondria ultrastructure was observed through transmission electron microscopy (TEM). Finally, mRNA and protein expressions were examined by quantitative real-time PCR (qRT-PCR) and western blot analysis.

RESULTS

The expression of FNDC5 was found to be significantly decreased in both in vivo and in vitro models. Treatment with irisin significantly suppressed ferroptosis and improved bone loss. This was demonstrated by reduced lipid peroxidation and iron overload, increased antioxidant capability, as well as the inhibition of the ferroptosis pathway in bone tissues. Furthermore, in vitro studies demonstrated that FNDC5 overexpression significantly improved HG-induced ferroptosis and promoted osteogenesis. Mechanistic investigations revealed that FNDC5 overexpression mitigated ferroptosis in osteoblasts by inhibiting the eukaryotic initiation factor 2 alpha (eIF2α)/activated transcription factor 4 (ATF4)/C/EBP-homologous protein (CHOP) pathway.

CONCLUSIONS

Collectively, our study uncovered the important role of FNDC5/irisin in regulating ferroptosis of diabetic osteopathy, which might be a potential therapeutic target.

Ferroptosis mechanisms and regulations in cardiovascular diseases in the past, present, and future

Cardiovascular diseases (CVDs) are the main diseases that endanger human health, and their risk factors contribute to high morbidity and a high rate of hospitalization. Cell death is the most important pathophysiology in CVDs. As one of the cell death mechanisms, ferroptosis is a new form of regulated cell death (RCD) that broadly participates in CVDs (such as myocardial infarction, heart transplantation, atherosclerosis, heart failure, ischaemia/reperfusion (I/R) injury, atrial fibrillation, cardiomyopathy (radiation-induced cardiomyopathy, diabetes cardiomyopathy, sepsis-induced cardiac injury, doxorubicin-induced cardiac injury, iron overload cardiomyopathy, and hypertrophic cardiomyopathy), and pulmonary arterial hypertension), involving in iron regulation, metabolic mechanism and lipid peroxidation. This article reviews recent research on the mechanism and regulation of ferroptosis and its relationship with the occurrence and treatment of CVDs, aiming to provide new ideas and treatment targets for the clinical diagnosis and treatment of CVDs by clarifying the latest progress in CVDs research.

A guideline on the molecular ecosystem regulating ferroptosis

Ferroptosis, an intricately regulated form of cell death characterized by uncontrolled lipid peroxidation, has garnered substantial interest since this term was first coined in 2012. Recent years have witnessed remarkable progress in elucidating the detailed molecular mechanisms that govern ferroptosis induction and defence, with particular emphasis on the roles of heterogeneity and plasticity. In this Review, we discuss the molecular ecosystem of ferroptosis, with implications that may inform and enable safe and effective therapeutic strategies across a broad spectrum of diseases.

Zn2+-dependent functional switching of ERp18, an ER-resident thioredoxin-like protein

ERp18 is an endoplasmic reticulum (ER)-resident thioredoxin (Trx) family protein, similar to cytosolic Trx1. The Trx-like domain occupies a major portion of the whole ERp18 structure, which is postulated to be an ER paralog of cytosolic Trx1. Here, we elucidate that zinc ion (Zn2+) binds ERp18 through its catalytic motif, triggering oligomerization of ERp18 from a monomer to a trimer. While the monomeric ERp18 has disulfide oxidoreductase activity, the trimeric ERp18 acquires scavenger activity for hydrogen peroxide (H2O2) in the ER. Depletion of ERp18 thus causes the accumulation of H2O2, which is produced during the oxidative folding of nascent polypeptides in the ER. ERp18 knockdown in C. elegans without Prx4 and GPx7/8, both of which are also known to have H2O2 scavenging activity in the ER, shortened the lifespan, suggesting that ERp18 may form a primitive and essential H2O2 scavenging system for the maintenance of redox homeostasis in the ER.

Driving factors of neuronal ferroptosis

Ferroptosis is an oxidative form of iron-dependent cell death characterized by the accumulation of lipid peroxides on membranes. Iron and lipids containing polyunsaturated fatty acids are essential for this process. Ferroptosis is central to several neurological diseases and underlies the importance of balanced iron and polyunsaturated fatty acid metabolism in the brain, particularly in neurons. Here, we reflect on the potential links between neuronal physiology and the accumulation of iron and peroxidated lipids, the mechanisms neurons use to protect themselves from ferroptosis, and the relationship between pathogenic protein deposition and ferroptosis in neurodegenerative disease. We propose that the unique physiology of neurons makes them especially vulnerable to ferroptosis.

Identification of ZIP8-induced ferroptosis as a major type of cell death in monocytes under sepsis conditions

Sepsis is a heterogenous syndrome with concurrent hyperinflammation and immune suppression. A prominent feature of immunosuppression during sepsis is the dysfunction and loss of monocytes; however, the major type of cell death contributing to this depletion, as well as its underlying molecular mechanisms, are yet to be identified. In this study, we confirmed the monocyte loss in septic patients based on a pooled gene expression data of periphery leukocytes. Using the collected reference gene sets from databases and published studies, we identified ferroptosis with a greater capacity to distinguish between sepsis and control samples than other cell death types. Further investigation on the molecular drivers, by a genetic algorithm-based feature selection and a weighted gene co-expression network analysis, revealed that zrt-/irt-like protein 8 (ZIP8), encoded by SLC39A8, was closely associated with ferroptosis of monocytes during sepsis. We validated the increase of ZIP8 of monocytes with in vivo and in vitro experiments. The in vitro studies also showed that downregulation of ZIP8 alleviated the lipopolysaccharide-induced lipid peroxidation, as well as restoring the reduction of GPX4, FTH1 and xCT. These findings suggest that ferroptosis might be a key factor in the loss of monocytes during sepsis, and that the heightened expression of ZIP8 may facilitate this progression.

Integrated bioinformatics analysis identifies a Ferroptosis-related gene signature as prognosis model and potential therapeutic target of bladder cancer

Background

Bladder cancer (BLCA) is one of the most prevalent cancers worldwide. Ferroptosis is a newly discovered form of non-apoptotic cell death that plays an important role in tumors. However, the prognostic value of ferroptosis-related genes (FRGs) in BLCA has not yet been well studied.

Method and materials

In this study, we performed consensus clustering based on FRGS and categorized BLCA patients into 2 clusters (C1 and C2). Immune cell infiltration score and immune score for each sample were computed using the CIBERSORT and ESTIMATE methods. Functional annotation of differentially expressed genes were performed by Gene Ontology (GO) and KEGG pathway enrichment analysis. Protein expression validation were confirmed in Human Protein Atlas. Gene expression validation were performed by qPCR in human bladder cancer cell lines lysis samples.

Result

C2 had a significant survival advantage and higher immune infiltration levels than C1. Additionally, C2 showed substantially higher expression levels of immune checkpoint markers than C1. According to the Cox and LASSO regression analyses, a novel ferroptosis-related prognostic signature was developed to predict the prognosis of BLCA effectively. High-risk and low-risk groups were divided according to risk scores. Kaplan-Meier survival analyses showed that the high-risk group had a shorter overall survival than the low-risk group throughout the cohort. Furthermore, a nomogram combining risk score and clinical features was developed. Finally, SLC39A7 was identified as a potential target in bladder cancer.

Discussion

In conclusion, we identified two ferroptosis-clusters with different prognoses using consensus clustering in BLCA. We also developed a ferroptosis-related prognostic signature and nomogram, which could indicate the outcome.

Breaking bad nucleotides: understanding the regulatory mechanisms of bacterial small alarmone hydrolases

Guanosine tetra- and pentaphosphate nucleotides, (p)ppGpp, function as central secondary messengers and alarmones in bacterial cell biology, signalling a range of stress conditions, including nutrient starvation and exposure to cell-wall-targeting antibiotics, and are critical for survival. While activation of the stringent response and alarmone synthesis on starved ribosomes by members of the RSH (Rel) class of proteins is well understood, much less is known about how single-domain small alarmone synthetases (SASs) and their corresponding alarmone hydrolases, the small alarmone hydrolases (SAHs), are regulated and contribute to (p)ppGpp homeostasis. The substrate spectrum of these enzymes has recently been expanded to include hyperphosphorylated adenosine nucleotides, suggesting that they take part in a highly complex and interconnected signalling network. In this review, we provide an overview of our understanding of the SAHs and discuss their structure, function, regulation, and phylogeny.

Cellular zinc metabolism and zinc signaling: from biological functions to diseases and therapeutic targets

Zinc metabolism at the cellular level is critical for many biological processes in the body. A key observation is the disruption of cellular homeostasis, often coinciding with disease progression. As an essential factor in maintaining cellular equilibrium, cellular zinc has been increasingly spotlighted in the context of disease development. Extensive research suggests zinc's involvement in promoting malignancy and invasion in cancer cells, despite its low tissue concentration. This has led to a growing body of literature investigating zinc's cellular metabolism, particularly the functions of zinc transporters and storage mechanisms during cancer progression. Zinc transportation is under the control of two major transporter families: SLC30 (ZnT) for the excretion of zinc and SLC39 (ZIP) for the zinc intake. Additionally, the storage of this essential element is predominantly mediated by metallothioneins (MTs). This review consolidates knowledge on the critical functions of cellular zinc signaling and underscores potential molecular pathways linking zinc metabolism to disease progression, with a special focus on cancer. We also compile a summary of clinical trials involving zinc ions. Given the main localization of zinc transporters at the cell membrane, the potential for targeted therapies, including small molecules and monoclonal antibodies, offers promising avenues for future exploration.

METTL9-SLC7A11 axis promotes hepatocellular carcinoma progression through ferroptosis inhibition

Methytransferase-like proteins 9 (METTL9) has been characterized as an oncogene in several cancers, however, its role in hepatocellular carcinoma (HCC) remains unknown. Here, we investigated the function and molecular mechanism of METTL9 in HCC. We showed that METTL9 expression was elevated in HCC, and its high expression was associated with poor survival outcomes. Knockdown of METTL9 observed a significant inhibition of HCC cell viability, migration, and invasion both in vitro and in vivo. By contrast, METTL9 overexpression HCC cells obtained stronger abilities in cell proliferation and migration. Mechanistically, we discovered that METTL9 knockdown led to a reduction in the expression level of SLC7A11, a key suppressor of ferroptosis, in turn, promoted ferroptosis in HCC cells, impeding the progression of HCC. Moreover, we have proved that targeting METTL9 could significantly restrain the growth of HCC patient-derived xenograft (PDX). Our study established METTL9 as a critical role in promoting HCC development and provides a foundation for further investigation and potential therapeutic interventions targeting ferroptosis in HCC.

Free zinc ions, as a major factor of ZnONP toxicity, disrupts free radical homeostasis in CCRF-CEM cells

Nanotechnology has become a ubiquitous part of our everyday life. Besides the already-known nanoparticles (NPs), plenty of new nanomaterials are being synthesized every day. Here, we explain the mechanism of the zinc oxide nanoparticles (ZnONPs) cytotoxicity in a cellular model of acute lymphoblastic leukaemia (CCRF-CEM). To do so, we investigated both possible hypotheses about the ZnONPs mechanism of toxicity: a free zinc ions release and/or reactive oxygen species (ROS) generation. Presented here results show that: Our results support the hypothesis that the mechanism of ZnONPs cytotoxicity is based on the release of free zinc ions. Nevertheless, both previously quoted hypotheses incompletely described the mechanism of action of ZnONPs. In this paper, we show that the mechanism of cytotoxicity of ZnONPs is based on the induction of reductive stress in CCRF-CEM cells, which is caused by free zinc ions released from ZnONPs. Therefore, the increase of oxidative stress markers is most likely a secondary response of the cells towards the Zn2+. These results provide a crucial expansion of the zinc ion hypothesis and thus explain the biphasic cellular response of CCRF-CEM cells treated with ZnONPs.

Therapeutic inhibition of ferroptosis in neurodegenerative disease

Iron accumulation has been associated with the etiology and progression of multiple neurodegenerative diseases (NDDs). The exact role of iron in these diseases is not fully understood, but an iron-dependent form of regulated cell death called ferroptosis could be key. Although there is substantial preclinical and clinical evidence that ferroptosis plays a role in NDD, there are still questions regarding how to target ferroptosis therapeutically, including which proteins to target, identification of clinically relevant biomarkers, and which patients might benefit most. Clinical trials of iron- and ferroptosis-targeted therapies are beginning to provide some answers, but there is growing interest in developing new ferroptosis inhibitors. We describe newly identified ferroptosis targets, opportunities, and challenges in NDD, as well as key considerations for progressing new therapeutics to the clinic.

Role of CELF2 in ferroptosis: Potential targets for cancer therapy (Review)

Ferroptosis is a novel form of regulated cellular necrosis that plays a critical role in promoting cancer progression and developing drug resistance. The main characteristic of ferroptosis is iron‑dependent lipid peroxidation caused by excess intracellular levels of reactive oxygen species. CUGBP ELAV‑like family number 2 (CELF2) is an RNA‑binding protein that is downregulated in various types of cancer and is associated with poor patient prognoses. CELF2 can directly bind mRNA to a variety of ferroptosis control factors; however, direct evidence of the regulatory role of CELF2 in ferroptosis is currently limited. The aim of the present review was to summarise the findings of previous studies on CELF2 and its role in regulating cellular redox homeostasis. The present review may provide insight into the possible mechanisms through which CELF2 affects ferroptosis and to provide recommendations for future studies.

Uncovering the dynamics of cellular responses induced by iron-carbohydrate complexes in human macrophages using quantitative proteomics and phosphoproteomics

Iron-carbohydrate complexes are widely used to treat iron deficiencies. Macrophages play a crucial role in the uptake and fate of these nanomedicines, however, how complexed iron carbohydrates are taken up and metabolized by macrophages is still not fully understood. Using a (phospho-)proteomics approach, we assessed differences in protein expression and phosphorylation in M2 macrophages triggered by iron sucrose (IS). Our results show that IS alters the expression of multiple receptors, indicative of a complex entry mechanism. Besides, IS induced an increase in intracellular ferritin, the loss of M2 polarization, protective mechanisms against ferroptosis, and an autophagic response. These data indicate that macrophages can use IS as a source of iron for its storage and later release, however, the excess of iron can cause oxidative stress, which can be successfully regulated by the cells. When comparing IS with ferric carboxymaltose (FCM) and iron isomaltoside-1000 (IIM), complexes with a higher carbohydrate ligand stability, we observed that FCM and IIM are metabolized at a slower rate, and trigger M2 polarization loss to a lower extent. These results indicate that the surface characteristics of the iron-carbohydrate complexes may influence the cell responses. Our data show that the application of (phospho-)proteomics can lead to a better understanding of metabolic processes, including the uptake, biodegradation and bioavailability of nanomedicines.

GREM1, LRPPRC and SLC39A4 as potential biomarkers of intervertebral disc degeneration: a bioinformatics analysis based on multiple microarray and single-cell sequencing data

BACKGROUND

Low back pain (LBP) has drawn much widespread attention and is a major global health concern. In this field, intervertebral disc degeneration (IVDD) is frequently the focus of classic studies. However, the mechanistic foundation of IVDD is unclear and has led to conflicting outcomes.

METHODS

Gene expression profiles (GSE34095, GSE147383) of IVDD patients alongside control groups were analyzed to identify differentially expressed genes (DEGs) in the GEO database. GSE23130 and GSE70362 were applied to validate the yielded key genes from DEGs by means of a best subset selection regression. Four machine-learning models were established to assess their predictive ability. Single-sample gene set enrichment analysis (ssGSEA) was used to profile the correlation between overall immune infiltration levels with Thompson grades and key genes. The upstream targeting miRNAs of key genes (GSE63492) were also analyzed. A single-cell transcriptome sequencing data (GSE160756) was used to define several cell clusters of nucleus pulposus (NP), annulus fibrosus (AF), and cartilaginous endplate (CEP) of human intervertebral discs and the distribution of key genes in different cell clusters was yielded.

RESULTS

By developing appropriate p-values and logFC values, a total of 6 DEGs was obtained. 3 key genes (LRPPRC, GREM1, and SLC39A4) were validated by an externally validated predictive modeling method. The ssGSEA results indicated that key genes were correlated with the infiltration abundance of multiple immune cells, such as dendritic cells and macrophages. Accordingly, these 4 key miRNAs (miR-103a-3p, miR-484, miR-665, miR-107) were identified as upstream regulators targeting key genes using the miRNet database and external GEO datasets. Finally, the spatial distribution of key genes in AF, CEP, and NP was plotted. Pseudo-time series and GSEA analysis indicated that the expression level of GREM1 and the differentiation trajectory of NP chondrocytes are generally consistent. GREM1 may mainly exacerbate the degeneration of NP cells in IVDD.

CONCLUSIONS

Our study gives a novel perspective for identifying reliable and effective gene therapy targets in IVDD.

Broadening horizons: the multifaceted functions of ferroptosis in kidney diseases

Ferroptosis is an iron-dependent programmed cell death pattern that is characterized by iron overload, reactive oxygen species (ROS) accumulation and lipid peroxidation. Growing viewpoints support that the imbalance of iron homeostasis and the disturbance of lipid metabolism contribute to tissue or organ injury in various kidney diseases by triggering ferroptosis. At present, the key regulators and complicated network mechanisms associated with ferroptosis have been deeply studied; however, its role in the initiation and progression of kidney diseases has not been fully revealed. Herein, we aim to discuss the features, key regulators and complicated network mechanisms associated with ferroptosis, explore the emerging roles of organelles in ferroptosis, gather its pharmacological progress, and systematically summarize the most recent discoveries about the crosstalk between ferroptosis and kidney diseases, including renal cell carcinoma (RCC), acute kidney injury (AKI), diabetic kidney disease (DKD), autosomal dominant polycystic kidney disease (ADPKD), renal fibrosis, lupus nephritis (LN) and IgA nephropathy. We further conclude the potential therapeutic strategies by targeting ferroptosis for the prevention and treatment of kidney diseases and hope that this work will provide insight for the further study of ferroptosis in the pathogenesis of kidney-related diseases.

PERK/ATF3-Reduced ER Stress on high potassium environment in the suppression of tumor ferroptosis

Potassium (K⁺) is a vital intracellular cation. In the human body, it regulates membrane potential, electrical excitation, protein synthesis, and cell death. Recent studies revealed that dying cancer cells release potassium into the tumor microenvironment (TME), thereby influencing cell survival-related events. Several investigations reported that potassium channels and high potassium levels influence apoptosis. Increasing extracellular potassium and inhibiting K⁺ efflux channels significantly block the apoptotic machinery. However, it is unknown whether a high-potassium environment also affects other types of cell death such as ferroptosis. In the present study, cell counting kit (CCK-8), colony formation ability, and 5-ethynyl-2'-deoxyuridine (EdU) assays demonstrated that a high-potassium environment reverses erastin-induced ferroptosis. RNA sequencing (RNA-Seq) and Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene ontology (GO) analyses indicated that high potassium levels attenuated the unfolded protein response that is characteristic of endoplasmic reticulum (ER) stress. The ER transmembrane proteins PRKR-like ER kinase (PERK), inositol-requiring enzyme 1α (IRE1α), and activating transcription factor 6 (ATF6) are recognized as ER stress sensors. Here, the PERK blocker GSK2606414 significantly rescued ferroptosis. The present work also disclosed that the ER-related gene activating transcription factor 3 (ATF3) played a vital role in regulating ferroptosis in a high-potassium environment. The foregoing results revealed the roles of potassium and the TME in cancer cell ferroptosis and provided a potential clinical therapeutic strategy for cancer.

Targeting ferroptosis as a cell death pathway in Melanoma: From molecular mechanisms to skin cancer treatment

Melanoma, the most aggressive form of human skin cancer, has been under investigation to reach the most efficient treatment. Surgical resection for early-diagnosed primary melanoma, targeted therapies, and immune checkpoint inhibitors for advanced/metastatic melanoma is the best clinical approach. Ferroptosis, a newly identified iron-dependent cell death pathway, which is morphologically and biochemically different from apoptosis and necrosis, has been reported to be involved in several cancers. Ferroptosis inducers could provide therapeutic options in case of resistance to conventional therapies for advanced/metastatic melanoma. Recently developed ferroptosis inducers, MEK and BRAF inhibitors, miRNAs such as miR-137 and miR-9, and novel strategies for targeting major histocompatibility complex (MHC) class II in melanoma can provide new opportunities for melanoma treatment. Combining ferroptosis inducers with targeted therapies or immune checkpoint inhibitors increases patient response rates. Here we review the mechanisms of ferroptosis and its environmental triggers. We also discuss the pathogenesis and current treatments of melanoma. Moreover, we aim to elucidate the relationship between ferroptosis and melanoma and ferroptosis implications to develop new therapeutic strategies against melanoma.

Restoration of metal homeostasis: a potential strategy against neurodegenerative diseases

Metal homeostasis is critical to normal neurophysiological activity. Metal ions are involved in the development, metabolism, redox and neurotransmitter transmission of the central nervous system (CNS). Thus, disturbance of homeostasis (such as metal deficiency or excess) can result in serious consequences, including neurooxidative stress, excitotoxicity, neuroinflammation, and nerve cell death. The uptake, transport and metabolism of metal ions are highly regulated by ion channels. There is growing evidence that metal ion disorders and/or the dysfunction of ion channels contribute to the progression of neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). Therefore, metal homeostasis-related signaling pathways are emerging as promising therapeutic targets for diverse neurological diseases. This review summarizes recent advances in the studies regarding the physiological and pathophysiological functions of metal ions and their channels, as well as their role in neurodegenerative diseases. In addition, currently available metal ion modulators and in vivo quantitative metal ion imaging methods are also discussed. Current work provides certain recommendations based on literatures and in-depth reflections to improve neurodegenerative diseases. Future studies should turn to crosstalk and interactions between different metal ions and their channels. Concomitant pharmacological interventions for two or more metal signaling pathways may offer clinical advantages in treating the neurodegenerative diseases.

Multifunctional Metallothioneins as a Target for Neuroprotection in Parkinson's Disease

Parkinson's disease (PD) is characterized by motor symptoms based on a loss of nigrostriatal dopaminergic neurons and by non-motor symptoms which precede motor symptoms. Neurodegeneration accompanied by an accumulation of α-synuclein is thought to propagate from the enteric nervous system to the central nervous system. The pathogenesis in sporadic PD remains unknown. However, many reports indicate various etiological factors, such as oxidative stress, inflammation, α-synuclein toxicity and mitochondrial impairment, drive neurodegeneration. Exposure to heavy metals contributes to these etiopathogenesis and increases the risk of developing PD. Metallothioneins (MTs) are cysteine-rich metal-binding proteins; MTs chelate metals and inhibit metal-induced oxidative stress, inflammation and mitochondrial dysfunction. In addition, MTs possess antioxidative properties by scavenging free radicals and exert anti-inflammatory effects by suppression of microglial activation. Furthermore, MTs recently received attention as a potential target for attenuating metal-induced α-synuclein aggregation. In this article, we summarize MTs expression in the central and enteric nervous system, and review protective functions of MTs against etiopathogenesis in PD. We also discuss neuroprotective strategies for the prevention of central dopaminergic and enteric neurodegeneration by targeting MTs. This review highlights multifunctional MTs as a target for the development of disease-modifying drugs for PD.

Data on the transcriptional response to MESH1 knockdown and mammalian stringent response

MESH1 is the metazoan homolog of bacterial SpoT, the main phosphatase that dephosphorylates and degrades (p)ppGpp, the alarmone involved in the bacterial stringent response. The functional role of MESH1 in human cells is unknown. To define the global transcriptional response to MESH1 knockdown, we employed microarrays to perform transcriptome analysis of H1975 when the MESH1 was knocked down using three independent siRNAs targeting MESH1. The changes of each gene were derived by zero-transformation, followed by filtering to derive the genes affected by MESH1 knockdown. These datasets showed the transcriptional features of the mammalian stringent response and identified a prominent TAZ repression. Thus, we performed a second experiment to determine the contribution of TAZ repression to the transcriptional response of MESH1 knockdown by comparing the effects of MESH1-knockdown gene signatures in H1975 cells transduced with control or constitutive active TAZ (TAZS89A). The transcriptional response of these two cells to MESH1 was derived by zero transformation, followed by the effects of TAZ restoration to define the contribution of TAZ repression to the transcriptome features of human stringent response. The transcriptome data will be useful for the mechanistic understanding of the functional role of MESH1 in human cancer cells.

A Systematic Study on Zinc-Related Metabolism in Breast Cancer

Breast cancer has become the most common cancer worldwide. Despite the major advances made in the past few decades in the treatment of breast cancer using a combination of chemotherapy, endocrine therapy, and immunotherapy, the genesis, treatment, recurrence, and metastasis of this disease continue to pose significant difficulties. New treatment approaches are therefore urgently required. Zinc is an important trace element that is involved in regulating various enzymatic, metabolic, and cellular processes in the human body. Several studies have shown that abnormal zinc homeostasis can lead to the onset and progression of various diseases, including breast cancer. This review highlights the role played by zinc transporters in pathogenesis, apoptosis, signal transduction, and potential clinical applications in breast cancer. Additionally, the translation of the clinical applications of zinc and associated molecules in breast cancer, as well as the recent developments in the zinc-related drug targets for breast cancer treatment, is discussed. These developments offer novel insights into understanding the concepts and approaches that could be used for the diagnosis and management of breast cancer.

COVID-19-induced neurological symptoms: focus on the role of metal ions

Neurological symptoms are prevalent in both the acute and post-acute phases of coronavirus disease 2019 (COVID-19), and they are becoming a major concern for the prognosis of COVID-19 patients. Accumulation evidence has suggested that metal ion disorders occur in the central nervous system (CNS) of COVID-19 patients. Metal ions participate in the development, metabolism, redox and neurotransmitter transmission in the CNS and are tightly regulated by metal ion channels. COVID-19 infection causes neurological metal disorders and metal ion channels abnormal switching, subsequently resulting in neuroinflammation, oxidative stress, excitotoxicity, neuronal cell death, and eventually eliciting a series of COVID-19-induced neurological symptoms. Therefore, metal homeostasis-related signaling pathways are emerging as promising therapeutic targets for mitigating COVID-19-induced neurological symptoms. This review provides a summary for the latest advances in research related to the physiological and pathophysiological functions of metal ions and metal ion channels, as well as their role in COVID-19-induced neurological symptoms. In addition, currently available modulators of metal ions and their channels are also discussed. Collectively, the current work offers a few recommendations according to published reports and in-depth reflections to ameliorate COVID-19-induced neurological symptoms. Further studies need to focus on the crosstalk and interactions between different metal ions and their channels. Simultaneous pharmacological intervention of two or more metal signaling pathway disorders may provide clinical advantages in treating COVID-19-induced neurological symptoms.

Understanding the mechanistic roles of environmental heavy metal stressors in regulating ferroptosis: adding new paradigms to the links with diseases

Ferroptosis is a new type of iron-dependent cell death induced by a failure of the lipid repair protein GPX4 or the Xc- antiporter, which is essential for glutathione production. Some heavy metals such as arsenic (As), cobalt (Co), cadmium (Cd), iron (Fe), magnesium (Mg), manganese (Mn), nickel (Ni), mercury (Hg) as well as zinc (Zn) are shown to induce ferroptotic cell death involving the generation of oxidative stress, mitochondrial dysfunctioning, lipid peroxidation, and several other cellular etiologies. However, selenium (Se) treatment has been shown to enhance adaptive transcription responses to protect cells from ferroptosis. Heavy metals like Cadmium exposure activated ALK4/5 signaling via Smad3 and Akt signaling which leads to cell death mechanism. Continuous exposure to a small dose of mercury can damage tissues, and methylmercury bind to sulfhydryl proteins and GSH, this elevates oxidative stress, free radical accumulation, glutathione depletion, mitochondrial damage, and inhibited the nuclear factor-κB pathway which leads to ferroptotic cell death. Animals exposed to nickel and cobalt may have increased lipid peroxidation which can induce ferroptosis. Glutathione depletion is caused by Zn intoxication and exposure to manganese. These metals are systemic toxins that have been shown adverse effects on humans. Ferroptosis has recently been related to several pathological disorders, including, Alzheimer's disease, Parkinson's disease, Huntington's disease, as well as cardiovascular disease, and any type of cancer. For these disorders and some heavy metal toxicity, ferroptosis suppression needs to be looked upon as a promising therapeutic choice.

Microglia ferroptosis is regulated by SEC24B and contributes to neurodegeneration

Iron dysregulation has been implicated in multiple neurodegenerative diseases, including Parkinson's disease (PD). Iron-loaded microglia are frequently found in affected brain regions, but how iron accumulation influences microglia physiology and contributes to neurodegeneration is poorly understood. Here we show that human induced pluripotent stem cell-derived microglia grown in a tri-culture system are highly responsive to iron and susceptible to ferroptosis, an iron-dependent form of cell death. Furthermore, iron overload causes a marked shift in the microglial transcriptional state that overlaps with a transcriptomic signature found in PD postmortem brain microglia. Our data also show that this microglial response contributes to neurodegeneration, as removal of microglia from the tri-culture system substantially delayed iron-induced neurotoxicity. To elucidate the mechanisms regulating iron response in microglia, we performed a genome-wide CRISPR screen and identified novel regulators of ferroptosis, including the vesicle trafficking gene SEC24B. These data suggest a critical role for microglia iron overload and ferroptosis in neurodegeneration.

Role of ferroptosis on tumor progression and immunotherapy

Ferroptosis is triggered by intracellular iron leading to accumulation of lipid peroxidation consequent promotion of cell death. Cancer cell exhibits ability to evade ferroptosis by activation of antioxidant signaling pathways such as SLC7A11/GPX4 axis. In addition to transcriptional regulation on ferroptosis by NRF2, SREBP1, YAP, and p53, ferroptosis is modulated by ubiquitination or autophagic degradation. Moreover, zinc or Ca²⁺ could modulate ferroptosis by inducing lipid peroxidation and ferroptosis. Induction of ferroptosis enhances immune cell activity such as T cells or macrophages, which is associated with the release of DAMPs (damage-associated molecular patterns) and IFNγ. Therefore, combined immune checkpoint inhibitors with ferroptosis inducers effectively enhance antitumor immunotherapy, whereas induction of ferroptosis could impair T cell activity or survival, suggesting that rational combined therapy for cancer is essential. In this review, we discussed the regulatory role of ferroptosis on tumor progression and immunotherapy.

GPX4 Alleviates Diabetes Mellitus-Induced Erectile Dysfunction by Inhibiting Ferroptosis

Pharmacological therapy of diabetes mellitus-induced erectile dysfunction (DMED) is intractable owig to the poor response to phosphodiesterase type 5 inhibitors (PDE5i). The surge in the number of diabetic patients makes it extremely urgent to find a novel therapy for DMED. Ferroptosis is a recently discovered form of cell death evoked by lipid peroxidation and is related to several diabetic complications. GPX4, an important phospholipid hydroperoxidase, can alleviate ferroptosis and maintain redox balance via reducing lipid peroxides. However, whether GPX4 can be a prospective target of DMED needs to be determined. Fifty rats were randomly divided into control group, DMED group, DMED + negative control group (DMED + NC group), DMED + low-dose group (1 × 10⁶ infectious units), and DMED + high-dose group (2 × 10⁶ infectious units). Erectile function was assessed 4 weeks after intracavernous injection of GPX4 or negative control lentivirus. The penile shafts were collected for subsequent molecular biological and histological analysis. The results demonstrated that erectile function of the rats in DMED and DMED + NC groups was extremely impaired and was improved in a dose-dependent manner with GPX4 lentivirus (GPX4-LV) injection. Additionally, upregulation of the ACSL4-LPCAT3-LOX pathway, iron overload, oxidative stress, fibrosis, and decreased endothelial and smooth muscle cell numbers were observed in the corpus cavernosum of DMED group. Meanwhile, the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway was inhibited, and the Ras homolog gene family member A (RhoA)/Rho-associated protein kinase (ROCK) pathway was promoted in DMED rats. The above histologic alterations and related molecular changes were alleviated after GPX4-LV injection. The results revealed that GPX4 improved erectile function by modulating ferroptosis during DMED progression. This finding is of paramount significance in deciphering the molecular mechanism of hyperglycemia-induced ferroptosis, thereby providing a prospective target for preventing the development of DMED.

Crosstalk between regulated necrosis and micronutrition, bridged by reactive oxygen species

The discovery of regulated necrosis revitalizes the understanding of necrosis from a passive and accidental cell death to a highly coordinated and genetically regulated cell death routine. Since the emergence of RIPK1 (receptor-interacting protein kinase 1)-RIPK3-MLKL (mixed lineage kinase domain-like) axis-mediated necroptosis, various other forms of regulated necrosis, including ferroptosis and pyroptosis, have been described, which enrich the understanding of pathophysiological nature of diseases and provide novel therapeutics. Micronutrients, vitamins, and minerals, position centrally in metabolism, which are required to maintain cellular homeostasis and functions. A steady supply of micronutrients benefits health, whereas either deficiency or excessive amounts of micronutrients are considered harmful and clinically associated with certain diseases, such as cardiovascular disease and neurodegenerative disease. Recent advance reveals that micronutrients are actively involved in the signaling pathways of regulated necrosis. For example, iron-mediated oxidative stress leads to lipid peroxidation, which triggers ferroptotic cell death in cancer cells. In this review, we illustrate the crosstalk between micronutrients and regulated necrosis, and unravel the important roles of micronutrients in the process of regulated necrosis. Meanwhile, we analyze the perspective mechanism of each micronutrient in regulated necrosis, with a particular focus on reactive oxygen species (ROS).

The Role Played by Ferroptosis in Osteoarthritis: Evidence Based on Iron Dyshomeostasis and Lipid Peroxidation

Ferroptosis, a recently discovered regulated cell death modality, is characterised by iron-dependent accumulation of lipid hydroperoxides, which can reach lethal levels but can be specifically reversed by ferroptosis inhibitors. Osteoarthritis (OA), the most common degenerative joint disease, is characterised by a complex pathogenesis involving mechanical overload, increased inflammatory mediator levels, metabolic alterations, and cell senescence and death. Since iron accumulation and oxidative stress are the universal pathological features of OA, the role played by ferroptosis in OA has been extensively explored. Increasing evidence has shown that iron dyshomeostasis and lipid peroxidation are closely associated with OA pathogenesis. Therefore, in this review, we summarize recent evidence by focusing on ferroptotic mechanisms and the role played by ferroptosis in OA pathogenesis from the perspectives of clinical findings, animal models, and cell research. By summarizing recent research advances that characterize the relationship between ferroptosis and OA, we highlight avenues for further research and potential therapeutic targets.

The crosstalk effect between ferrous and other ions metabolism in ferroptosis for therapy of cancer

Ferroptosis is an iron-dependent cell death process characterized by excessive accumulation of reactive oxygen species and lipid peroxidation. The elucidation of ferroptosis pathways may lead to novel cancer therapies. Current evidence suggests that the mechanism of ferroptosis can be summarized as oxidative stress and antioxidant defense mechanisms. During this process, ferrous ions play a crucial role in cellular oxidation, plasma membrane damage, reactive oxygen species removal imbalance and lipid peroxidation. Although, disregulation of intracellular cations (Fe²⁺, Ca²⁺, Zn²⁺, etc.) and anions (Cl^-, etc.) have been widely reported to be involved in ferroptosis, their specific regulatory mechanisms have not been established. To further understand the crosstalk effect between ferrous and other ions in ferroptosis, we reviewed the ferroptosis process from the perspective of ions metabolism. In addition, the role of ferrous and other ions in tumor therapy is briefly summarized.

Maternal serum zinc level is associated with risk of preeclampsia: A systematic review and meta-analysis

Background

Preeclampsia (PE) is a multi-organ syndrome that onsets in the second half of pregnancy. It is the second leading cause of maternal death globally. The homeostasis of zinc (Zn) levels is important for feto-maternal health.

Objective

We aimed to collect all studies available to synthesize the evidence regarding the association between maternal Zn levels and the risk of preeclampsia.

Methods

A systematic review and meta-analysis was conducted via searching seven electronic databases [PubMed, Web of Science, Embase, African Journals Online (AJOL), ClinicalTrial.gov, and two Chinese databases: Wanfang and Chinese National Knowledge Infrastructure, CNKI]. Studies reporting maternal serum Zn levels in pregnant women with or without preeclampsia were included. Eligible studies were assessed through Newcastle-Ottawa Scale (NOS) and the meta-analysis was performed via RevMan and Stata. The random-effects method (REM) was used for the meta-analysis with 95% confidence interval (CI). The pooled result was assessed using standard mean difference (SMD). The heterogeneity test was carried out using I 2 statistics, and the publication bias was evaluated using Begg's and Egger's test. Meta-regression and sensitivity analysis was performed via Stata software.

Results

A total of 51 studies were included in the final analysis. 6,947 participants from 23 countries were involved in our study. All studies went through the quality assessment. The pooled results showed that maternal serum Zn levels were lower in preeclamptic women than in healthy pregnant women (SMD: -1.00, 95% CI: -1.29, -0.70). Sub-group analysis revealed that geographical, economic context, and disease severity may further influence serum Zn levels and preeclampsia.

Limitations

There are significant between-study heterogeneity and publication bias among included studies.

Conclusions

A lower level of maternal Zn was associated with increased risks of preeclampsia. The associations were not entirely consistent across countries and regions worldwide.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=337069, Identifier: CRD42022337069.

The role of metal ions in the Golgi apparatus

The Golgi apparatus is a membrane-bound organelle that functions as a central role in the secretory pathway. Since the discovery of the Golgi apparatus, its structure and function have attracted ever-increasing attention from researchers. Recently, it has been demonstrated that metal ions are necessary for the Golgi apparatus to maintain its proper structure and functions. Given that metal ions play an important role in various biological processes, their abnormal homeostasis is related to many diseases. Therefore, in this paper, we reviewed the uptake and release mechanisms of the Golgi apparatus Ca²⁺ , Cu, and Zn²⁺ . Furthermore, we describe the diseases associated with Golgi apparatus Ca²⁺ , Cu, and Zn²⁺ imbalance.

Ferroptosis as a mechanism of non-ferrous metal toxicity

Ferroptosis is a recently discovered form of regulated cell death, implicated in multiple pathologies. Given that the toxicity elicited by some metals is linked to alterations in iron metabolism and induction of oxidative stress and lipid peroxidation, ferroptosis might be involved in such toxicity. Although direct evidence is insufficient, certain pioneering studies have demonstrated a crosstalk between metal toxicity and ferroptosis. Specifically, the mechanisms underlying metal-induced ferroptosis include induction of ferritinophagy, increased DMT-1 and TfR cellular iron uptake, mitochondrial dysfunction and mitochondrial reactive oxygen species (mitoROS) generation, inhibition of Xc-system and glutathione peroxidase 4 (GPX4) activity, altogether resulting in oxidative stress and lipid peroxidation. In addition, there is direct evidence of the role of ferroptosis in the toxicity of arsenic, cadmium, zinc, manganese, copper, and aluminum exposure. In contrast, findings on the impact of cobalt and nickel on ferroptosis are scant and nearly lacking altogether for mercury and especially lead. Other gaps in the field include limited studies on the role of metal speciation in ferroptosis and the critical cellular targets. Although further detailed studies are required, it seems reasonable to propose even at this early stage that ferroptosis may play a significant role in metal toxicity, and its modulation may be considered as a potential therapeutic tool for the amelioration of metal toxicity.

The Organelle-Specific Regulations and Epigenetic Regulators in Ferroptosis

Ferroptosis is fairly different from other types of cell-death in biochemical processes, morphological changes and genetics as a special programmed cell-death. Here we summarize the current literatures on ferroptosis, including the cascade reaction of key material metabolism in the process, dysfunction of organelles, the relationship between different organelles and the way positive and negative key regulatory factors to affect ferroptosis in the epigenetic level. Based on material metabolism or epigenetic regulation, it is obvious that the regulatory network of ferroptosis is interrelated and complex.

Metazoan stringent-like response mediated by MESH1 phenotypic conservation via distinct mechanisms

All organisms are constantly exposed to various stresses, necessitating adaptive strategies for survival. In bacteria, the main metabolic stress-coping mechanism is the stringent response, which is triggered by the accumulation of “alarmone” (p)ppGpp to arrest proliferation and reprogram the transcriptome. The level of (p)ppGpp is regulated by its synthetase RelA and its hydrolase SpoT. MESH1 is the metazoan homolog of bacterial SpoT that regulates the bacterial stringent response by degrading the alarmone (p)ppGpp. While MESH1, like SpoT, can also dephosphorylate (p)ppGpp, mammalian cells do not have significant levels of this metabolite, and the relevant enzymatic activities and function of MESH1 have remained a mystery. Through genetic and biochemical analyses, we have solved the long-held mystery and identified MESH1 as the first mammalian cytosolic NADPH phosphatase involved in ferroptosis. Furthermore, we discovered that MESH1 removal leads to proliferation arrest, translation inhibition, and a prominent transcriptional and metabolic response. Therefore, MESH1 knockdown triggers a novel stress response with phenotypic conservation with the bacterial stringent response via distinct substrates and molecular pathways. Here, we summarize the background of the MESH1, illustrate the striking conservation of phenotypes in different organisms during evolution and discuss remaining questions in the field.

Serum metabolomic analysis of men on a low-carbohydrate diet for biochemically recurrent prostate cancer reveals the potential role of ketogenesis to slow tumor growth: a secondary analysis of the CAPS2 diet trial

BACKGROUND

Systemic treatments for prostate cancer (PC) have significant side effects. Thus, newer alternatives with fewer side effects are urgently needed. Animal and human studies suggest the therapeutic potential of low carbohydrate diet (LCD) for PC. To test this possibility, Carbohydrate and Prostate Study 2 (CAPS2) trial was conducted in PC patients with biochemical recurrence (BCR) after local treatment to determine the effect of a 6-month LCD intervention vs. usual care control on PC growth as measured by PSA doubling time (PSADT). We previously reported the LCD intervention led to significant weight loss, higher HDL, and lower triglycerides and HbA1c with a suggested longer PSADT. However, the metabolic basis of these effects are unknown.

METHODS

To identify the potential metabolic basis of effects of LCD on PSADT, serum metabolomic analysis was performed using baseline, month 3, and month 6 banked sera to identify the metabolites significantly altered by LCD and that correlated with varying PSADT.

RESULTS

LCD increased the serum levels of ketone bodies, glycine and hydroxyisocaproic acid. Reciprocally, LCD reduced the serum levels of alanine, cytidine, asymmetric dimethylarginine (ADMA) and 2-oxobutanoate. As high ADMA level is shown to inhibit nitric oxide (NO) signaling and contribute to various cardiovascular diseases, the ADMA repression under LCD may contribute to the LCD-associated health benefit. Regression analysis of the PSADT revealed a correlation between longer PSADT with higher level of 2-hydroxybutyric acids, ketone bodies, citrate and malate. Longer PSADT was also associated with LCD reduced nicotinamide, fructose-1, 6-biphosphate (FBP) and 2-oxobutanoate.

CONCLUSION

These results suggest a potential association of ketogenesis and TCA metabolites with slower PC growth and conversely glycolysis with faster PC growth. The link of high ketone bodies with longer PSADT supports future studies of ketogenic diets to slow PC growth.

Down-Regulation of Activating Transcription Factor 3 (ATF3) in Hepatoblastoma and Its Relationship with Ferroptosis

Purpose

The molecular mechanisms and signal pathways of ferroptosis in hepatoblastoma (HB) have not yet been clarified. In previous studies, activating transcription factor 3 (ATF3) was reported to be correlated with several tumors, but the clinical significance of ATF3 has never been determined. Herein, we investigated the clinicopathological value and mechanisms of ATF3 in regulating ferroptosis in HB.

Methods

The mRNA microarray and RNA-sequencing data of 402 samples from our hospital and public databases were used to estimate ATF3 expression and assess its clinical role in HB. The standard mean difference (SMD) and summary receiver operating characteristic curves were utilized to judge the discrimination ability of ATF3 between HB and non-HB liver tissues. We examined the expression variation of ATF3 in HB cells after the treatment with erastin. We also predicted the target genes of ATF3 as a transcriptional factor from public Chromatin Immunoprecipitation-sequencing data and selected the ferroptosis-related genes for a signaling pathway analysis.

Results

In ten series, the pooled SMD for ATF3 was −0.91, demonstrating that ATF3 expression was predominantly lower in HB than in non-HB liver tissues. ATF3 down-regulation showed moderate potential to distinguish HB from non-HB liver tissues (area under curves = 0.83, 95% confidence interval = 0.79–0.86). Altogether, 4855 putative targets of ATF3 as a transcriptional factor were collected, among which, 60 genes were ferroptosis-related.

Conclusion

The down-regulated ATF3 expression may play a vital role in the occurrence of HB possible partially by regulating ferroptosis.

Organelle-specific regulation of ferroptosis

Ferroptosis, a cell death modality characterized by iron-dependent lipid peroxidation, is involved in the development of multiple pathological conditions, including ischemic tissue damage, infection, neurodegeneration, and cancer. The cellular machinery responsible for the execution of ferroptosis integrates multiple pro-survival or pro-death signals from subcellular organelles and then 'decides' whether to engage the lethal process or not. Here, we outline the evidence implicating different organelles (including mitochondria, lysosomes, endoplasmic reticulum, lipid droplets, peroxisomes, Golgi apparatus, and nucleus) in the ignition or avoidance of ferroptosis, while emphasizing their potential relevance for human disease and their targetability for pharmacological interventions.

Cystine and Methionine Deficiency Promotes Ferroptosis by Inducing B-Cell Translocation Gene 1

Ferroptosis is a type of programmed necrosis triggered by iron-dependent lipid peroxidation. We investigated the role of B-cell translocation gene 1 (BTG1) in cystine and methionine deficiency (CST/Met (−))-mediated cell death. CST/Met (−) depleted reduced and oxidized glutathione in hepatocyte-derived cells, increased prostaglandin-endoperoxide synthase 2 expression, and promoted reactive oxygen species accumulation and lipid peroxidation, as well as necrotic cell death. CST/Met (−)-mediated cell death and lipid peroxidation was specifically inhibited by pretreatment with ferroptosis inhibitors. In parallel with cell death, CST/Met (−) blocked global protein translation and increased the expression of genes associated with the integrated stress response. Moreover, CST/Met (−) significantly induced BTG1 expression. Using a BTG1 promoter-harboring reporter gene and siRNA, activating transcription factor 4 (ATF4) was identified as an essential transcription factor for CST/Met (−)-mediated BTG1 induction. Although knockout of BTG1 in human HAP1 cells did not affect the accumulation of reactive oxygen species induced by CST/Met (−), BTG1 knockout significantly decreased the induction of genes associated with the integrated stress response, and reduced lipid peroxidation and cell death in response to CST/Met (−). The results demonstrate that CST/Met (−) induces ferroptosis by activating ATF4-dependent BTG1 induction.

Construction and analysis of a novel ferroptosis-related gene signature predicting prognosis in lung adenocarcinoma

Ferroptosis is a newly discovered, iron‐dependent, nonapoptotic form of programmed cell death that plays an important role in the development of lung adenocarcinoma (LUAD). In this study, ferroptosis‐related genes (FRGs) were identified from the FerrDb dataset, and the mRNA expression profiles and corresponding clinical data of LUAD patients were downloaded from the University of California, Santa Cruz (UCSC) databases. Data from LUAD patients from the Gene Expression Omnibus (GEO) dataset were used as the verification set. Cox and Lasso regression analyses were used to screen the FRGs with prognostic value, and six prognostic‐related FRGs were selected to construct prognostic risk score signatures. Immunohistochemistry was utilized to manifest the differential expression of six FRGs in tumor and normal tissues at the protein level. Functional enrichment analysis indicated that FRGs were mainly enriched in ferroptosis‐related pathways. Patients were divided into high‐ and low‐risk groups based on the median risk score. The Kaplan–Meier survival curves confirmed that patients with a high score had significantly worse overall survival. Receiver operating characteristic (ROC) curves proved that the prognostic signature has good sensitivity and specificity for predicting the prognosis of LUAD patients. Nomogram analysis showed that the prognostic signature has potential independent prognostic value. Moreover, the prognostic signature has been shown to be significantly associated with some clinical features (T stage, N stage, tumor stage, and survival status) as well as many immune‐activity‐related genes and immune‐checkpoint‐related genes. In conclusion, we constructed a prognostic signature consisting of six FGRs, which can provide a reference for predicting the prognosis of LUAD patients.

Regulation of Ferroptosis Pathway by Ubiquitination

Ferroptosis is an iron-dependent form of programmed cell death, which plays crucial roles in tumorigenesis, ischemia–reperfusion injury and various human degenerative diseases. Ferroptosis is characterized by aberrant iron and lipid metabolisms. Mechanistically, excess of catalytic iron is capable of triggering lipid peroxidation followed by Fenton reaction to induce ferroptosis. The induction of ferroptosis can be inhibited by sufficient glutathione (GSH) synthesis via system Xc^– transporter-mediated cystine uptake. Therefore, induction of ferroptosis by inhibition of cystine uptake or dampening of GSH synthesis has been considered as a novel strategy for cancer therapy, while reversal of ferroptotic effect is able to delay progression of diverse disorders, such as cardiopathy, steatohepatitis, and acute kidney injury. The ubiquitin (Ub)–proteasome pathway (UPP) dominates the majority of intracellular protein degradation by coupling Ub molecules to the lysine residues of protein substrate, which is subsequently recognized by the 26S proteasome for degradation. Ubiquitination is crucially involved in a variety of physiological and pathological processes. Modulation of ubiquitination system has been exhibited to be a potential strategy for cancer treatment. Currently, more and more emerged evidence has demonstrated that ubiquitous modification is involved in ferroptosis and dominates the vulnerability to ferroptosis in multiple types of cancer. In this review, we will summarize the current findings of ferroptosis surrounding the viewpoint of ubiquitination regulation. Furthermore, we also highlight the potential effect of ubiquitination modulation on the perspective of ferroptosis-targeted cancer therapy.

Effects of Iron and Zinc on Mitochondria: Potential Mechanisms of Glaucomatous Injury

Glaucoma is the most substantial cause of irreversible blinding, which is accompanied by progressive retinal ganglion cell damage. Retinal ganglion cells are energy-intensive neurons that connect the brain and retina, and depend on mitochondrial homeostasis to transduce visual information through the brain. As cofactors that regulate many metabolic signals, iron and zinc have attracted increasing attention in studies on neurons and neurodegenerative diseases. Here, we summarize the research connecting iron, zinc, neuronal mitochondria, and glaucomatous injury, with the aim of updating and expanding the current view of how retinal ganglion cells degenerate in glaucoma, which can reveal novel potential targets for neuroprotection.

The regulation of ferroptosis by MESH1 through the activation of the integrative stress response

All organisms exposed to metabolic and environmental stresses have developed various stress adaptive strategies to maintain homeostasis. The main bacterial stress survival mechanism is the stringent response triggered by the accumulation “alarmone” (p)ppGpp, whose level is regulated by RelA and SpoT. While metazoan genomes encode MESH1 (Metazoan SpoT Homolog 1) with ppGpp hydrolase activity, neither ppGpp nor the stringent response is found in metazoa. The deletion of Mesh1 in Drosophila triggers a transcriptional response reminiscent of the bacterial stringent response. However, the function of MESH1 remains unknown until our recent discovery of MESH1 as the first cytosolic NADPH phosphatase that regulates ferroptosis. To further understand whether MESH1 knockdown triggers a similar transcriptional response in mammalian cells, here, we employed RNA-Seq to analyze the transcriptome response to MESH1 knockdown in human cancer cells. We find that MESH1 knockdown induced different genes involving endoplasmic reticulum (ER) stress, especially ATF3, one of the ATF4-regulated genes in the integrative stress responses (ISR). Furthermore, MESH1 knockdown increased ATF4 protein, eIF2a phosphorylation, and induction of ATF3, XBPs, and CHOP mRNA. ATF4 induction contributes to ~30% of the transcriptome induced by MESH1 knockdown. Concurrent ATF4 knockdown re-sensitizes MESH1-depleted RCC4 cells to ferroptosis, suggesting its role in the ferroptosis protection mediated by MESH1 knockdown. ATF3 induction is abolished by the concurrent knockdown of NADK, implicating a role of NADPH accumulation in the integrative stress response. Collectively, these results suggest that MESH1 depletion triggers ER stress and ISR as a part of its overall transcriptome changes to enable stress survival of cancer cells. Therefore, the phenotypic similarity of stress tolerance caused by MESH1 removal and NADPH accumulation is in part achieved by ISR to regulate ferroptosis.