Integrated regulation of stress responses, autophagy and survival by altered intracellular iron stores

ALKBH3-mediated m1A demethylation promotes the malignant progression of acute myeloid leukemia by regulating ferroptosis through the upregulation of ATF4 expression

To investigate the role of ALKBH3 in acute myeloid leukemia (AML), we constructed an animal model of xenotransplantation of AML. Our study demonstrated that ALKBH3-mediated m1A demethylation inhibits ferroptosis in KG-1 cells by increasing ATF4 expression, thus promoting the development of AML. These findings suggest that reducing ALKBH3 expression may be a potential strategy to mitigate AML progression.

Background: Acute myeloid leukemia (AML) is characterized by the unrestrained proliferation of myeloid cells. Studies have shown that ALKBH3 is upregulated in most tumors, but the role of ALKBH3 in AML remains unclear.Methods: In this study, we investigated the function of ALKBH3 in AML cells (KG-1) by immunofluorescence, ELISA, flow cytometry, HE staining, and Western blotting.Results: Our results revealed that ALKBH3 is upregulated in AML and that the downregulation of ALKBH3 inhibited KG-1 cell proliferation and promoted cell apoptosis; at the same time, ALKBH3 upregulated ATF4 expression through m1A demethylation, and the knockdown of ATF4 resulted in increased ferrous iron content; TFR1, ACSL4, and PTGS2 expression; and ROS and MDA levels, whereas SOD and GSH levels and the expression levels of ATF4, SLC7A11, GPX4, and FTH1 decreased in KG-1 cells, thereby promoting ferroptosis. Mechanistically, ALKBH3-mediated m1A demethylation suppressed ferroptosis in KG-1 cells by increasing ATF4 expression, thereby promoting the development of AML.Conclusions: Our study indicated that reducing the expression of ALKBH3 might be a potential target for improving AML symptoms.

Crosstalk of autophagy and ferroptosis in cardiovascular diseases: from pathophysiology to novel therapy

Cardiovascular diseases (CVDs) are characterized by high morbidity and mortality rates, imposing substantial epidemiological and economic burdens worldwide. Among the multifaceted mechanisms implicated in CVDs, autophagy and ferroptosis, two intimately linked cellular processes, emerge as pivotal pathophysiological contributors. Autophagy, as an evolutionary conserved process that mediates the degradation and recycling of intracellular components, including proteins and organelles, exerts critical regulatory effects on iron metabolism and lipid homeostasis through various specialized forms, including ferritinophagy and lipophagy. Conversely, ferroptosis, an iron dependent form of cell death, involves oxidative stress and the accumulation of lipid peroxides, often triggered by iron overload and the dysfunction of glutathione peroxidase 4 (GPX4). The intricate crosstalk between these two processes, particularly ferritinophagy-mediated iron regulation influencing ferroptosis, plays a crucial role in diverse CVDs contexts. Key regulatory molecules, such as Beclin-1 and nuclear factor E2-related factor 2 (Nrf2), function as central hubs, orchestrating the intricate interplay between autophagy and ferroptosis. Through a comprehensive examination of these mechanisms across various CVDs pathologies, we summarize the latest findings and outline potential therapeutic strategies targeting the crosstalk between autophagy and ferroptosis. As the inaugural review focusing on autophagy-ferroptosis interactions in CVDs, this work significantly enriches our understanding of the pathophysiology of CVDs and identifies novel therapeutic targets with potential for precision medicine interventions in managing CVDs.

Idiopathic pulmonary fibrosis microenvironment: Novel mechanisms and research directions

Idiopathic Pulmonary Fibrosis (IPF) is a progressive interstitial lung disease marked by increasing dyspnea and respiratory failure. The underlying mechanisms remain poorly understood, given the complexity of its pathogenesis. This review investigates the microenvironment of IPF to identify novel mechanisms and therapeutic avenues. Studies have revealed that various cell types, including alveolar epithelial cells, fibroblasts, myofibroblasts, and immune cells, are integral to disease progression, engaging in cellular stress responses and inflammatory regulation via signaling pathways such as TGF-β, Wnt, mTOR, and ROS. Non-coding RNAs, particularly miRNAs, are critical in IPF and may serve as diagnostic and prognostic biomarkers. Regarding treatment, mesenchymal stem cells (MSCs) and their extracellular vesicles (EVs) or non-vesicular derivatives offer promise by modulating immune responses, enhancing tissue repair, and inhibiting fibrosis. Additionally, alterations in the lung microbiota are increasingly recognized as a contributing factor to IPF progression, offering fresh insights into potential treatments. Despite the encouraging results of MSC-based therapies, the precise mechanisms and clinical applications remain subjects of ongoing research. This review emphasizes the significance of the IPF microenvironment and highlights the need for further exploration to develop effective therapies that could enhance patient outcomes.

GLUT1 maintains esophageal cancer stem cell-like characteristics by inhibiting autophagy-dependent ferroptosis via EGFR

Esophageal cancer, a highly malignant tumor with poor prognosis, is characterized by the presence of cancer stem cells (CSCs) that drive tumor initiation, metastasis, and recurrence. This study investigates the molecular mechanism by which glucose transporter 1 (GLUT1) maintains esophageal CSC-like properties through regulation of autophagy-dependent ferroptosis via epidermal growth factor receptor (EGFR). Using shRNA to knock down GLUT1 or EGFR and constructing a GLUT1 overexpression vector in KYSE520 cells, we employed western blotting, qRT-PCR, flow cytometry, sphere formation, Transwell assays, and xenograft models to assess stemness markers (NANOG, OCT4, SOX2), autophagic flux (LC3B, P62, Beclin1), and ferroptosis-related parameters (ROS, Fe2+, GSH, GPX4, COX2). Mechanistic analyses included co-immunoprecipitation to validate the GLUT1-EGFR interaction, chloroquine to inhibit autophagy, and cycloheximide/MG132 to evaluate EGFR protein stability. Results showed that GLUT1 depletion reduced CSC marker expression, increased ROS and Fe2+ levels, depleted GSH, and induced lipid peroxidation, sensitizing cells to ferroptosis while activating autophagy (elevated LC3 II/I, Beclin1; reduced P62); autophagy inhibition exacerbated cell death, indicating a protective role for autophagy in this context. GLUT1 directly bound to EGFR, stabilizing the receptor by blocking ubiquitin-proteasome-mediated degradation, whereas EGFR knockdown enhanced autophagic flux and reversed GLUT1-overexpression-induced ferroptosis resistance and stemness maintenance. In vivo, GLUT1 knockdown suppressed tumor growth and lung metastasis, and clinical samples revealed a positive correlation between GLUT1 and EGFR expression, linked to advanced TNM stages and poor survival. Collectively, these findings demonstrate that GLUT1 preserves esophageal CSC-like characteristics by stabilizing EGFR to inhibit autophagy-dependent ferroptosis, highlighting targeting GLUT1 as a potential therapeutic strategy to eliminate CSCs and combat esophageal cancer progression.

Beta-Lactam Antibiotics Promote Extracellular Vesicle Production of Staphylococcus aureus Through ROS-Mediated Lipid Metabolic Reprogramming

Bacterial extracellular vesicles (EVs) are natural reservoirs of biological active substances. They exhibit promising application in developing bioproducts such as vaccine, drug-delivery system and anticancer agent. However, the low yield of naturally secreted EVs during bacterial growth is a bottleneck factor that restricts EV applications. In this study, we showed that sub-minimum inhibitory concentration (MIC) of β-lactams boosted EV production in various Staphylococcus aureus strains. The expression of penicillin-binding protein (PBP) genes increased after β-lactam treatment, and the inactivation of alternative PBPs promoted EV secretion of S. aureus. We also demonstrated that sub-MIC β-lactams promoted EV production via a reactive oxygen species (ROS)-dependent pathway. Deletion of redundant pbp genes enhanced oxacillin (OXA)-stimulated ROS levels. Transcriptomic and lipidomic analyses revealed that OXA-induced ROS triggered lipid metabolic reprogramming in S. aureus. Particularly, ROS promoted lipid peroxidation (LPO) and increased the biosynthesis of phosphatidic acid (PA) and lipoteichoic acid (LTA) that contributed to EV generation. Furthermore, OXA treatment altered the diversity of EV-loaded proteins. OXA-treated ∆ agr /OXAEVs induced stronger Dengue EDIII-specific antibodies in BALB/c mice than did ∆ agrEVs. Overall, this study provided mechanic insights into β-lactam-promoted EV production in S. aureus, and highlighted the potential strategies to prepare EVs for various applications.

WBP1 regulates mitochondrial function and ferroptosis to modulate chemoresistance in colorectal cancer

Chemoresistance continues to pose a significant challenge in managing colorectal cancer (CRC), resulting in unfavorable outcomes for patients. Recent findings indicate that ferroptosis, an innovative type of regulated cell death, might influence chemoresistance. In this research, we explored how WW domain-binding protein 1 (WBP1) affects mitochondrial function, cell growth, ferroptosis, and chemoresistance in CRC cells. By employing both genetic and pharmacological methods, we found that WBP1 is essential for maintaining mitochondrial respiration in CRC cells. WBP1 depletion impaired mitochondrial function, leading to reduced cell proliferation and increased ferroptosis. Exogenous mitochondria from wild-type cells restored mitochondrial function, cell proliferation, and suppressed ferroptosis in WBP1-deficient cells, indicating that mitochondrial function acts downstream of WBP1. Importantly, we demonstrated that targeting WBP1 or its mediated mitochondrial function sensitized chemoresistant CRC cells to 5-fluorouracil and oxaliplatin by inducing ferroptosis. Furthermore, we analyzed transcriptome data from CRC patients, which indicated that increased WBP1 expression correlated with poor outcomes for patients receiving chemotherapy, thus highlighting the clinical significance of our observations. Collectively, our results pinpoint WBP1 as a significant modulator of mitochondrial function and ferroptosis in CRC cells and imply that targeting WBP1 may represent a viable approach to tackling chemoresistance. These insights offer a deeper understanding of the molecular pathways underlying CRC chemoresistance and may guide the development of new treatment options.

Iron and Inflammatory Cytokines Synergistically Induce Colonic Epithelial Cell Ferroptosis in Colitis

Inflammatory bowel disease (IBD) is an inflammatory disease that occurs to the intestinal tract. Many patients with IBD often develop anemia and often receive oral iron supplementation. Many of them develop non-compliance with oral iron therapy, but the mechanisms are not well understood. We interrogated whether colonic epithelial iron overload impacts cell viability and disease severity. We observed increased expression of iron importers and iron accumulation in mature colonocytes in dextran sulfate sodium (DSS)-induced acute colitis and in humans with active colitis. Administration of hepcidin increased epithelial iron overload and aggravated colonic inflammation in DSS-treated mice and IL10-/- mice. Hepcidin-induced iron accumulation increased colonic epithelial death, which was prevented by treatment with Trolox, a vitamin E analog and a scavenger of lipid peroxides. By using cultured Caco-2 cells, we showed that iron and inflammatory cytokines (TNF-α and IL-1β) induced a synergistic increase in the number of necrotic cells. We then showed that the combined treatment by hepcidin and cytokines increased labile iron content and lipid peroxidation in Caco-2 cells. Moreover, liproxstatin-1, a ferroptosis inhibitor, and deferoxamine, an iron chelator, both abolished the hepcidin/cytokines induced death of Caco-2 cells, suggesting ferroptosis. We further elucidated that inflammatory cytokines promote lipid peroxidation and ferroptosis by inducing NOX1-dependent exhaustion of reduced glutathione (GSH). Collectively, our findings demonstrate that the inflammatory context predisposes colonic epithelial cells to iron overload mediated ferroptosis, exacerbating colonic inflammation.

Inhibition of Phosphodiesterase 4 Suppresses Neuronal Ferroptosis After Cerebral Ischemia/Reperfusion

We have previously shown that inhibition of phosphodiesterase 4 (PDE4) protects against cerebral ischemia/reperfusion injury. However, it remains unclear whether and how PDE4 affects ferroptosis under cerebral ischemia/reperfusion conditions. In this study, we found that overexpression of PDE4B in HT-22 cells exacerbated the detrimental effects of oxygen-glucose deprivation/reoxygenation (OGD/R), including a decrease in cell viability and glutathione (GSH) levels and an increase in Fe2+ content. PDE4B knockdown mitigated the effects of OGD/R, as evidenced by decreased oxidative stress, lactate dehydrogenase (LDH) release, Fe2+ content, and nuclear receptor coactivator 4 (NCOA4) expression. PDE4B knockdown also enhanced the levels of GSH, ferroportin (FPN), and ferritin heavy chain 1 (FTH1). Consistently, inhibition of PDE4 by roflumilast (Roflu) produced similar effects as PDE4B knockdown. Roflu also ameliorated the morphology and membrane potential of the mitochondria. Glutathione peroxidase 4 (GPX4) knockdown blocked the effects of Roflu on cell viability and lipid peroxidation. Moreover, we found that nuclear factor erythroid 2-related factor 2 (Nrf-2) knockdown decreased GPX4 expression. In addition, Nrf-2 knockdown led to enhanced lipid peroxidation, LDH release, and iron levels, while the GSH and FPN levels decreased. More crucially, PDE4 inhibition decreased infarct volume, alleviated oxidative stress, and restored the expression levels of ferroptosis-associated proteins in middle cerebral artery occlusion/reperfusion (MCAO/R) rats. Interestingly, the GPX4 inhibitor RSL3 blocked the neuroprotective effects of Roflu in rats subjected to MCAO/R. Thus, PDE4 inhibition significantly inhibits neuronal ferroptosis by activating the Nrf-2/GPX4 pathway. These data indicate the existence of a novel mechanism underlying the neuroprotective effects of PDE4 inhibition.

Intracellular metal ion-based chemistry for programmed cell death

Intracellular metal ions play essential roles in multiple physiological processes, including catalytic action, diverse cellular processes, intracellular signaling, and electron transfer. It is crucial to maintain intracellular metal ion homeostasis which is achieved by the subtle balance of storage and release of metal ions intracellularly along with the influx and efflux of metal ions at the interface of the cell membrane. Dysregulation of intracellular metal ions has been identified as a key mechanism in triggering programmed cell death (PCD). Despite the importance of metal ions in initiating PCD, the molecular mechanisms of intracellular metal ions within these processes are infrequently discussed. An in-depth understanding and review of the role of metal ions in triggering PCD may better uncover novel tools for cancer diagnosis and therapy. Specifically, the essential roles of calcium (Ca2+), iron (Fe2+/3+), copper (Cu+/2+), and zinc (Zn2+) ions in triggering PCD are primarily explored in this review, and other ions like manganese (Mn2+/3+/4+), cobalt (Co2+/3+) and magnesium ions (Mg2+) are briefly discussed. Further, this review elaborates on the underlying chemical mechanisms and summarizes these metal ions triggering PCD in cancer therapy. This review bridges chemistry, immunology, and biology to foster the rational regulation of metal ions to induce PCD for cancer therapy.

Ilexgenin A Alleviates Myocardial Ferroptosis in Response to Ischemia Reperfusion Injury via the SIRT1 Pathway

Myocardial ischemia-reperfusion (I/R) injury has emerged as an increasingly serious cardiovascular health concern worldwide, with ferroptosis playing a pivotal role as the underlying pathogenic process. This study aimed to investigate the pharmacological effect and mechanism of Ilexgenin A on cardiomyocyte ferroptosis induced by myocardial I/R injury. In vivo, we established a murine anterior descending artery ligation/recanalization model to evaluate the cardioprotective effect of Ilexgenin A. Bioinformatics analysis, molecular docking, and Surface Plasmon Resonance imaging were conducted to predict the pharmacological targets of Ilexgenin A. In vitro experiments, the neonatal rat cardiomyocytes (NRCMs) were utilized to further explore the mechanism of Ilexgenin A in inhibiting ferroptosis using chemiluminescence and immunofluorescence staining, electron microscopy, biochemical assay, RT-qPCR, western blotting, and so on. The results showed that Ilexgenin A protected against cardiac dysfunction, ameliorated myocardial ferroptosis and mitochondrial damage induced by murine myocardial I/R injury via the silence information regulator 1 (SIRT1) pathway, the trend was consistently observed in NRCMs. Additionally, the SIRT1 knockdown by siRNA delivery partially abrogated the beneficial effects of Ilexgenin A on ameliorating mitochondrial damage, and then aggravated erastin-induced ferroptosis in NRCMs. Overall, Our research demonstrated that the inhibition of ferroptosis via the SIRT1 pathway was one of the mechanisms by which Ilexgenin A exerted cardioprotective effect.

Regulating Mitochondrial Aging via Targeting the Gut-Bone Axis in BMSCs With Oral Hydrogel Microspheres to Inhibit Bone Loss

The gut-bone axis is a promising target for osteoporosis treatment, yet existing delivery systems lack precise targeting. Herein, an oral hydrogel microsphere system (E7-Lipo@Alg/Cs) is developed using gas microfluidic and ionic crosslinking technologies to deliver drugs to bone marrow mesenchymal stem cells (BMSCs) via the gut-bone axis, regulating mitochondrial aging. A BMSC-affine peptide is conjugated onto liposomes encapsulating Fisetin, followed by incorporation into alginate-calcium hydrogel microspheres. Chitosan is electrostatically adsorbed onto the microsphere surface, creating a core-shell structure that adheres to intestinal epithelial cells, withstands gastric acid, and facilitates targeted delivery to BMSCs through the intestinal-bone axis. In vitro, the system effectively enhances mitochondrial function and reverses BMSC aging, while in vivo studies demonstrate prolonged drug activity, restored osteogenic differentiation, and bone regeneration. RNA-seq indicates activation of the AMPK-SIRT1 pathway, reversing mitochondrial aging in BMSCs and promoting aged bone tissue regeneration. This oral hydrogel microsphere system provides a targeted and efficient strategy for regulating mitochondrial function and preventing bone loss, offering significant clinical potential for osteoporosis treatment.

Melatonin Attenuates Ferritinophagy/Ferroptosis by Acting on Autophagy in the Liver of an Autistic Mouse Model BTBR T+Itpr3tf/J

Autism spectrum disorders (ASDs) are a pool of neurodevelopment disorders in which social impairment is the main symptom. Presently, there are no definitive medications to cure the symptoms but the therapeutic strategies that are taken ameliorate them. The purpose of this study was to investigate the effects of melatonin (MLT) in treating ASDs using an autistic mouse model BTBR T+Itpr3tf/J (BTBR). We evaluated the hepatic cytoarchitecture and some markers of autophagy, ferritinophagy/ferroptosis, in BTBR mice treated and not-treated with MLT. The hepatic morphology and the autophagy and ferritinophagy/ferroptosis pathways were analyzed by histological, immunohistochemical, and Western blotting techniques. We studied p62 and microtubule-associated protein 1 light chain 3 B (LC3B) for evaluating the autophagy; nuclear receptor co-activator 4 (NCOA4) and long-chain-coenzyme synthase (ACSL4) for monitoring ferritinophagy/ferroptosis. The liver of BTBR mice revealed that the hepatocytes showed many cytoplasmic inclusions recognized as Mallory-Denk bodies (MDBs); the expression and levels of p62 and LC3B were downregulated, whereas ACSL4 and NCOA4 were upregulated, as compared to control animals. MLT administration to BTBR mice ameliorated liver damage and reduced the impairment of autophagy and ferritinophagy/ferroptosis. In conclusion, we observed that MLT alleviates liver damage in BTBR mice by improving the degradation of intracellular MDBs, promoting autophagy, and suppressing ferritinophagy/ferroptosis.

Jun modulates endoplasmic reticulum stress-associated ferroptosis in dorsal root ganglia neurons during neuropathic pain by regulating Timp1

Neuropathic pain (NP) is a complex disorder caused by lesions or diseases affecting the somatosensory nervous system, severely impacting patients' quality of life. Recent studies suggest ferroptosis may be involved in NP induction, but its precise mechanisms remain unclear. We used GO and KEGG pathway enrichment analyses to functionally annotate ferroptosis-related differentially expressed genes (FRDs). Through STRING and the maximum cluster centrality (MCC) algorithm, we identified five hub FRDs (Jun, Timp1, Egfr, Cdkn1a, Cdkn2a). Single-cell analysis revealed significant expression of Jun and Timp1 in neurons. Our study confirmed the association between ferroptosis and endoplasmic reticulum stress (ERS) in NP and validated changes in hub FRD expression across various NP animal models. In vitro experiments demonstrated that Jun regulates neuronal ferroptosis and ERS, particularly by modulating Timp1 expression. Transcription factor prediction and JASPAR binding site analysis elucidated the regulatory network involving Jun. ROC curve analysis of external datasets highlighted the diagnostic potential of hub FRDs and ERS-related differentially expressed genes (ERSRDs) in NP. Using the Comparative Toxicogenomics Database (CTD), we identified estradiol (E2) as a potential therapeutic drug targeting hub FRDs and ERSRDs. Molecular docking predicted its binding sites with Jun and Timp1, and in vivo experiments confirmed that E2 alleviated NP and reversed the expression of Jun and Timp1. This study underscores the crucial role of Jun and Timp1 in the interplay between ferroptosis and ERS, offering new insights and promising avenues for NP treatment.

Fighting ischemia-reperfusion injury: Focusing on mitochondria-derived ferroptosis

Ischemia-reperfusion injury (IRI) is a major cause of mortality and morbidity. Current treatments for IRI have limited efficacy and novel therapeutic strategies are needed. Mitochondrial dysfunction not only initiates IRI but also plays a significant role in ferroptosis pathogenesis. Recent studies have highlighted that targeting mitochondrial pathways is a promising therapeutic approach for ferroptosis-induced IRI. The association between ferroptosis and IRI has been reviewed many times, but our review provides the first comprehensive overview with a focus on recent mitochondrial research. First, we present the role of mitochondria in ferroptosis. Then, we summarize the evidence on mitochondrial manipulation of ferroptosis in IRI and review recent therapeutic strategies aimed at targeting mitochondria-related ferroptosis to mitigate IRI. We hope our review will provide new ideas for the treatment of IRI and accelerate the transition from bench to bedside.

The Role of Iron in Intestinal Mucus: Perspectives from Both the Host and Gut Microbiota

Although research on the role of iron in host immunity has a history spanning decades, it is only relatively recently that attention has been directed toward the biological effects of iron on the intestinal mucus layer, prompted by an evolving understanding of the role of this material in immune defense. The mucus layer, secreted by intestinal goblet cells, covers the intestinal epithelium, and given its unique location, interactions between the host and gut microbiota, as well as among constituent microbiota, occur frequently within the mucus layer. Iron, as an essential nutrient for the vast majority of life forms, regulates immune responses from both the host and microbial perspectives. In this review, we summarize the iron metabolism of both the host and gut microbiota and describe how iron contributes to intestinal mucosal homeostasis via the intestinal mucus layer with respect to both host and constituent gut microbiota. The findings described herein offer a new perspective on iron-mediated intestinal mucosal barrier function.

Targeting PKCα alleviates iron overload in diabetes and hemochromatosis through the inhibition of ferroportin

ABSTRACT

Ferroportin (Fpn) is the only iron exporter, playing a crucial role in systemic iron homeostasis. Fpn is negatively regulated by its ligand hepcidin, but other potential regulators in physiological and disease conditions remain poorly understood. Diabetes is a metabolic disorder that develops body iron loading with unknown mechanisms. By using diabetic mouse models and human duodenal specimens, we demonstrated that intestinal Fpn expression was increased in diabetes in a hepcidin-independent manner. Protein kinase C (PKC) is hyperactivated in diabetes. We showed that PKCα was required to sustain baseline Fpn expression and diabetes-induced Fpn upregulation in the enterocytes and macrophages. Knockout of PKCα abolished diabetes-associated iron overload. Mechanistically, activation of PKCα increased the exocytotic trafficking of Fpn and decreased the endocytic trafficking of Fpn in the resting state. Hyperactive PKCα also suppressed hepcidin-induced ubiquitination, internalization, and degradation of Fpn. We further observed that iron loading in the enterocytes and macrophages activated PKCα, acting as a novel mechanism to enhance Fpn-dependent iron efflux. Finally, we demonstrated that the loss-of-function of PKCα and pharmacological inhibition of PKC significantly alleviated hereditary hemochromatosis-associated iron overload. Our study has highlighted, to our knowledge, for the first time, that PKCα is an important positive regulator of Fpn and a new target in the control of iron homeostasis.

Investigation of the mutual crosstalk between ER stress and PI3K/AKT/mTOR signaling pathway in iron overload-induced liver injury in chicks

Iron is an essential element for the normal functioning of living organisms, but excessive iron deposition can lead to organ damage. This study aims to investigate the interaction between the endoplasmic reticulum stress signaling pathway and the PI3K/AKT/mTOR signaling pathway in liver injury induced by iron overload in chicks. Rspectively, 150 one-day-old broilers were divided into three groups and supplemented with 50 (C), 500 (E1), and 1000 (E2) mg ferrous sulfate monohydrate/kg in the basal diet. Samples were taken after continuous feeding for 14 days. The results showed that iron overload could upregulate the levels of ALT and AST. Histopathological examination revealed bleeding in the central vein of the liver accompanied by inflammatory cell infiltration. Hoechst staining showed that the iron overload group showed significant bright blue fluorescence, and ultrastructural observations showed chromatin condensation as well as mitochondrial swelling and cristae disorganization in the iron overload group. RT-qPCR and Western blot results showed that iron overload upregulated the expression of Bax, Caspase-3, Caspase-9, GRP78, GRP94, P-PERK, ATF4, eIF2α, IRE1, and ATF6, while downregulating the expression of Bcl-2 and the PI3K/AKT/mTOR pathway. XBP-1 splicing experiment showed significant splicing of XBP-1 gene after iron overload. PCA and correlation analysis suggested a potential association between endoplasmic reticulum stress, the PI3K/AKT/mTOR signaling pathway, and liver injury in chicks. In summary, iron overload can induce cell apoptosis and liver injury by affecting endoplasmic reticulum stress and the PI3K/AKT/mTOR signaling pathway.

Sephin1 enhances integrated stress response and autophagy to alleviate myocardial ischemia-reperfusion injury in mice

OBJECTIVE

Integrated stress response (ISR) is activated to promote cell survival by maintaining the phosphorylation of eukaryotic translation initiation factor 2 (eIF2α). We investigated whether Sephin1 enhances ISR and attenuates myocardial ischemia-reperfusion (MIR) injury.

METHODS

Male C57BL/6 J mice were injected with Sephin1 (2 mg/kg,i.p.) 30 min before surgery to establish a model of MIR with 45 min ischemia and 180 min reperfusion. In vitro, the H9C2 cell line with hypoxia-reoxygenation (H/R) was used to simulate MIR. Myocardial injury was evaluated by echocardiography, histologic observation after staining with TTC and H&E and electron microscopy. ISR, autophagy and apoptosis in vivo and in vitro were evaluated by immunoblotting, immunohistochemistry, immunofluorescence, and flow cytometry, respectively. Global protein synthesis was determined using a non-radioactive SUnSET Assay based on the puromycin method. Autophinib, an autophagy-specific inhibitor, was used to investigate the correlation between autophagy and apoptosis in the presence of Sephin1.

RESULTS

In vivo, Sephin1 significantly reduced myocardial injury and improved the cardiac function in MIR mice. Sephin1 administration prolonged ISR, reduced cell apoptosis, and promoted autophagy. In vitro, Sephin1 increased the number of stress granules (SGs) and autophagic vesicles, enhanced ISR and related protein synthesis suppression, and reduced cell apoptosis. Autophinib partly reversed autophagosome formation and apoptosis in H9c2 cells.

CONCLUSIONS

Sephin1 enhances ISR and related protein synthesis suppression, ameliorates myocardial apoptosis, and promotes autophagy during MIR stress. Sephin1 could act as a noval ISR enhancer for managing acute myocardial ischemia disease.

Aging and Autophagy: Roles in Musculoskeletal System Injury

Aging is a multifactorial process that ultimately leads to a decline in physiological function and a consequent reduction in the health span, and quality of life in elderly population. In musculoskeletal diseases, aging is often associated with a gradual loss of skeletal muscle mass and strength, resulting in reduced functional capacity and an increased risk of chronic metabolic diseases, leading to impaired function and increased mortality. Autophagy is a highly conserved physiological process by which cells, under the regulation of autophagy-related genes, degrade their own organelles and large molecules by lysosomal degradation. This process is unique to eukaryotic cells and is a strict regulator of homeostasis, the maintenance of energy and substance balance. Autophagy plays an important role in a wide range of physiological and pathological processes such as cell homeostasis, aging, immunity, tumorigenesis and neurodegenerative diseases. On the one hand, under mild stress conditions, autophagy mediates the restoration of homeostasis and proliferation, reduction of the rate of aging and delay of the aging process. On the other hand, under more intense stress conditions, an inadequate suppression of autophagy can lead to cellular aging. Conversely, autophagy activity decreases during aging. Due to the interrelationship between aging and autophagy, limited literature exists on this topic. Therefore, the objective of this review is to summarize the current concepts on aging and autophagy in the musculoskeletal system. The aim is to better understand the mechanisms of age-related changes in bone, joint and muscle, as well as the interaction relationship between autophagy and aging. Its goal is to provide a comprehensive perspective for the improvement of diseases of the musculoskeletal system.

Targeting NKAα1 to treat Parkinson's disease through inhibition of mitophagy-dependent ferroptosis

Dysfunction of the Na+/K+-ATPase (NKA) has been documented in various neurodegenerative diseases, yet the specific role of NKAα1 in Parkinson's disease (PD) remains incompletely understood. In this investigation, we utilized NKAα1 haploinsufficiency (NKAα1+/-) mice to probe the influence of NKAα1 on dopaminergic (DA) neurodegeneration induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Our findings reveal that NKAα1+/- mice displayed a heightened loss of DA neurons and more pronounced motor dysfunction compared to the control group when exposed to MPTP. Intriguingly, this phenomenon coincided with the activation of ferroptosis and impaired mitophagy both in vivo and in vitro. To scrutinize the role and underlying mechanism of NKAα1 in PD, we employed DR-Ab, an antibody targeting the DR-region of the NKA α subunit. Our study demonstrates that the administration of DR-Ab effectively reinstated the membrane abundance of NKAα1, thereby mitigating MPTP-induced DA neuron loss and subsequent improvement in behavioral deficit. Mechanistically, DR-Ab heightened the formation of the surface NKAα1/SLC7A11 complex, inhibiting SLC7A11-dependent ferroptosis. Moreover, DR-Ab disrupted the cytosolic interaction between NKAα1 and Parkin, facilitating the translocation of Parkin to mitochondria and enhancing the process of mitophagy. In conclusion, this study establishes NKAα1 as a key regulator of ferroptosis and mitophagy, identifying its DR-region as a promising therapeutic target for PD.

Regulation of translation in response to iron deficiency in human cells

Protein synthesis is a highly energy-consuming process that is downregulated in response to many environmental stresses or adverse conditions. Studies in the yeast Saccharomyces cerevisiae have shown that bulk translation is inhibited during adaptation to iron deficiency, which is consistent with its requirement for ribosome biogenesis and recycling. Although iron deficiency anemia is the most common human nutritional disorder, how iron modulates translation in mammals is poorly understood. Studies during erythropoiesis have shown that iron bioavailability is coordinated with globin synthesis via bulk translation regulation. However, little is known about the control of translation during iron limitation in other tissues. Here, we investigated how iron depletion affects protein synthesis in human osteosarcoma U-2 OS cells. By adding an extracellular iron chelator, we observed that iron deficiency limits cell proliferation, induces autophagy, and decreases the global rate of protein synthesis. Analysis of specific molecular markers indicates that the inhibition of bulk translation upon iron limitation occurs through the eukaryotic initiation factor eIF2α and mechanistic target of rapamycin (mTOR) pathways. In contrast to other environmental and nutritional stresses, iron depletion does not trigger the assembly of messenger ribonucleoprotein stress granules, which typically form upon polysome disassembly.

Endoplasmic reticulum stress: bridging inflammation and obesity-associated adipose tissue

Obesity presents a significant global health challenge, increasing the susceptibility to chronic conditions such as diabetes, cardiovascular disease, and hypertension. Within the context of obesity, lipid metabolism, adipose tissue formation, and inflammation are intricately linked to endoplasmic reticulum stress (ERS). ERS modulates metabolism, insulin signaling, inflammation, as well as cell proliferation and death through the unfolded protein response (UPR) pathway. Serving as a crucial nexus, ERS bridges the functionality of adipose tissue and the inflammatory response. In this review, we comprehensively elucidate the mechanisms by which ERS impacts adipose tissue function and inflammation in obesity, aiming to offer insights into targeting ERS for ameliorating metabolic dysregulation in obesity-associated chronic diseases such as hyperlipidemia, hypertension, fatty liver, and type 2 diabetes.

Iron overload in hypothalamic AgRP neurons contributes to obesity and related metabolic disorders

Iron overload is closely associated with metabolic dysfunction. However, the role of iron in the hypothalamus remains unclear. Here, we find that hypothalamic iron levels are increased, particularly in agouti-related peptide (AgRP)-expressing neurons in high-fat-diet-fed mice. Using pharmacological or genetic approaches, we reduce iron overload in AgRP neurons by central deferoxamine administration or transferrin receptor 1 (Tfrc) deletion, ameliorating diet-induced obesity and related metabolic dysfunction. Conversely, Tfrc-mediated iron overload in AgRP neurons leads to overeating and adiposity. Mechanistically, the reduction of iron overload in AgRP neurons inhibits AgRP neuron activity; improves insulin and leptin sensitivity; and inhibits iron-induced oxidative stress, endoplasmic reticulum stress, nuclear factor κB signaling, and suppression of cytokine signaling 3 expression. These results highlight the critical role of hypothalamic iron in obesity development and suggest targets for treating obesity and related metabolic disorders.

Flvcr1a deficiency promotes heme-based energy metabolism dysfunction in skeletal muscle

The definition of cell metabolic profile is essential to ensure skeletal muscle fiber heterogeneity and to achieve a proper equilibrium between the self-renewal and commitment of satellite stem cells. Heme sustains several biological functions, including processes profoundly implicated with cell metabolism. The skeletal muscle is a significant heme-producing body compartment, but the consequences of impaired heme homeostasis on this tissue have been poorly investigated. Here, we generate a skeletal-muscle-specific feline leukemia virus subgroup C receptor 1a (FLVCR1a) knockout mouse model and show that, by sustaining heme synthesis, FLVCR1a contributes to determine the energy phenotype in skeletal muscle cells and to modulate satellite cell differentiation and muscle regeneration.

Ferroptosis and endoplasmic reticulum stress in ischemic stroke

Ferroptosis is a form of non-apoptotic programmed cell death, and its mechanisms mainly involve the accumulation of lipid peroxides, imbalance in the amino acid antioxidant system, and disordered iron metabolism. The primary organelle responsible for coordinating external challenges and internal cell demands is the endoplasmic reticulum, and the progression of inflammatory diseases can trigger endoplasmic reticulum stress. Evidence has suggested that ferroptosis may share pathways or interact with endoplasmic reticulum stress in many diseases and plays a role in cell survival. Ferroptosis and endoplasmic reticulum stress may occur after ischemic stroke. However, there are few reports on the interactions of ferroptosis and endoplasmic reticulum stress with ischemic stroke. This review summarized the recent research on the relationships between ferroptosis and endoplasmic reticulum stress and ischemic stroke, aiming to provide a reference for developing treatments for ischemic stroke.

Chlorantraniliprole induces mitophagy, ferroptosis, and cytokine homeostasis imbalance in grass carp (Ctenopharyngodon idella) hepatocytes via the mtROS-mitochondrial fission/fusion axis

Chlorantraniliprole (CAP) is a bis-amide pesticide used for pest control mainly in agricultural production activities and rice-fish co-culture systems. CAP residues cause liver damage in non-target organism freshwater fish. However, it is unclear whether CAP-exposure-induced liver injury in fish is associated with mitochondrial dysfunction-mediated mitophagy, ferroptosis, and cytokines. Therefore, we established grass carp hepatocyte models exposed to different concentrations of CAP (20, 40, and 80 μM) in vitro. MitoSOX probe, JC-1 staining, immunofluorescence double staining, Fe2+ staining, lipid peroxidation staining, qRT-PCR, and Western blot were used to verify the physiological regulatory mechanism of CAP induced liver injury. In the present study, the CAP-treated groups exhibited down-regulation of antioxidant-related enzyme activities and accumulation of peroxides. CAP treatment induced an increase in mitochondrial reactive oxygen species (mtROS) levels and altered expression of mitochondrial fission/fusion (Drp1, Fis1, Mfn1, Mfn2, and Opa1) genes in grass carp hepatocytes. In addition, mitophagy (Parkin, Pink1, p62, LC3II/I, and Beclin-1), ferroptosis (GPX4, COX2, ACSL4, FTH, and NCOA4), and cytokine (IFN-γ, IL-18, IL-17, IL-6, IL-10, IL-1β, IL-2, and TNF-α)-related gene expression was significantly altered. Collectively, these findings suggest that CAP exposure drives mitophagy activation, ferroptosis occurrence, and cytokine homeostasis imbalance in grass carp hepatocytes by triggering mitochondrial dysfunction mediated by the mtROS-mitochondrial fission/fusion axis. This study partly explained the physiological regulation mechanism of grass carp hepatocyte injury induced by insecticide CAP from the physiological and biochemical point of view and provided a basis for evaluating the safety of CAP environmental residues to non-target organisms.

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.

Magnesium promotes vascularization and osseointegration in diabetic states

Diabetes has long been considered a risk factor in implant therapy and impaired wound healing in soft and hard oral tissues. Magnesium has been proved to promote bone healing under normal conditions. Here, we elucidate the mechanism by which Mg2+ promotes angiogenesis and osseointegration in diabetic status. We generated a diabetic mice model and demonstrated the alveolar bone healing was compromised, with significantly decreased angiogenesis. We then developed Mg-coating implants with hydrothermal synthesis. These implants successfully improved the vascularization and osseointegration in diabetic status. Mechanically, Mg2+ promoted the degradation of Kelch-like ECH-associated protein 1 (Keap1) and the nucleation of nuclear factor erythroid 2-related factor 2 (Nrf2) by up-regulating the expression of sestrin 2 (SESN2) in endothelial cells, thus reducing the elevated levels of oxidative stress in mitochondria and relieving endothelial cell dysfunction under hyperglycemia. Altogether, our data suggested that Mg2+ promoted angiogenesis and osseointegration in diabetic mice by regulating endothelial mitochondrial metabolism.

Mitochondrial-Oriented Injectable Hydrogel Microspheres Maintain Homeostasis of Chondrocyte Metabolism to Promote Subcellular Therapy in Osteoarthritis

Subcellular mitochondria serve as sensors for energy metabolism and redox balance, and the dynamic regulation of functional and dysfunctional mitochondria plays a crucial role in determining cells' fate. Selective removal of dysfunctional mitochondria at the subcellular level can provide chondrocytes with energy to prevent degeneration, thereby treating osteoarthritis. Herein, to achieve an ideal subcellular therapy, cartilage affinity peptide (WYRGRL)-decorated liposomes loaded with mitophagy activator (urolithin A) were integrated into hyaluronic acid methacrylate hydrogel microspheres through microfluidic technology, named HM@WY-Lip/UA, that could efficiently target chondrocytes and selectively remove subcellular dysfunctional mitochondria. As a result, this system demonstrated an advantage in mitochondria function restoration, reactive oxygen species scavenging, cell survival rescue, and chondrocyte homeostasis maintenance through increasing mitophagy. In a rat post-traumatic osteoarthritis model, the intra-articular injection of HM@WY-Lip/UA ameliorated cartilage matrix degradation, osteophyte formation, and subchondral bone sclerosis at 8 weeks. Overall, this study indicated that HM@WY-Lip/UA provided a protective effect on cartilage degeneration in an efficacious and clinically relevant manner, and a mitochondrial-oriented strategy has great potential in the subcellular therapy of osteoarthritis.

Research Progress on the Effect of Autophagy and Exosomes on Liver Fibrosis

Chronic liver disease is a known risk factor for the development of liver cancer, and the development of microRNA (miRNA) liver therapies has been hampered by the difficulty of delivering miRNA to damaged tissues. In recent years, numerous studies have shown that hepatic stellate cell (HSC) autophagy and exosomes play an important role in maintaining liver homeostasis and ameliorating liver fibrosis. In addition, the interaction between HSC autophagy and exosomes also affects the progression of liver fibrosis. In this paper, we review the research progress of mesenchymal stem cell-derived exosomes (MSC-EVs) loaded with specific miRNA and autophagy, and their related signaling pathways in liver fibrosis, which will provide a more reliable basis for the use of MSC-EVs for therapeutic delivery of miRNAs targeting the chronic liver disease.

Sodium Sulfite-Triggered Hepatocyte Ferroptosis via mtROS/Lysosomal Membrane Permeabilization-Mediated Lysosome Iron Efflux

Sodium sulfite is a widely used preservative in the food industry. Ferroptosis has been a newly discovered form of iron-dependent oxidative cell death in recent years. However, the potential connection between sodium sulfite and ferroptosis has not been explored. In our study, we observed the abnormal expression of ferroptosis marker protein in vivo, suggesting that sodium sulfite caused ferroptosis in vivo. Next, our study revealed that sodium sulfite caused the overproduction of mitochondrial reactive oxygen species (mtROS) in the AML-12 cells. It is well established that reactive oxygen species (ROS) can induce lysosomal membrane permeabilization. After lysosomal membrane permeabilization occurs, the outflow of Fe2+ in lysosomes triggers the Fenton reaction and subsequently results in the increase of intracellular ROS level, which is closely related to ferroptosis. As speculated, acridine orange (AO) staining and LysoTracker red staining showed that sodium sulfite-induced lysosomal membrane permeabilization could be alleviated by mtROS scavenger TEMPO. In addition, TEMPO, lysosomal stabilizer mannose, and lysosomal iron chelator deferoxamine (DFO) inhibited sodium sulfite-induced ferroptosis. Overall, the results showed that sodium sulfite induced lysosomal iron efflux through the mtROS-lysosomal membrane permeabilization pathway and eventually led to ferroptosis. Our study might provide a new mechanism for the hepatotoxicity of sodium sulfite and a theoretical basis for the risk assessment of sodium sulfite as a food additive.

Differences in hepatocellular iron metabolism underlie sexual dimorphism in hepatocyte ferroptosis

Males show higher incidence and severity than females in hepatic injury and many liver diseases, but the mechanisms are not well understood. Ferroptosis, an iron-mediated lipid peroxidation-dependent death, plays an important role in the pathogenesis of liver diseases. We determined whether hepatocyte ferroptosis displays gender difference, accounting for sexual dimorphism in liver diseases. Compared to female hepatocytes, male hepatocytes were much more vulnerable to ferroptosis by iron and pharmacological inducers including RSL3 and iFSP1. Male but not female hepatocytes exhibited significant increases in mitochondrial Fe2+ and mitochondrial ROS (mtROS) contents. Female hepatocytes showed a lower expression of iron importer transferrin receptor 1 (TfR1) and mitochondrial iron importer mitoferrin 1 (Mfrn1), but a higher expression of iron storage protein ferritin heavy chain 1 (FTH1). It is well known that TfR1 expression is positively correlated with ferroptosis. Herein, we showed that silencing FTH1 enhanced while knockdown of Mfrn1 decreased ferroptosis in HepG2 cells. Removing female hormones by ovariectomy (OVX) did not dampen but rather enhanced hepatocyte resistance to ferroptosis. Mechanistically, OVX potentiated the decrease in TfR1 and increase in FTH1 expression. OVX also increased FSP1 expression in ERK-dependent manner. Elevation in FSP1 suppressed mitochondrial Fe2+ accumulation and mtROS production, constituting a novel mechanism of FSP1-mediated inhibition of ferroptosis. In conclusion, differences in hepatocellular iron handling between male and female account, at least in part, for sexual dimorphism in induced ferroptosis of the hepatocytes.

Why Is Iron Deficiency/Anemia Linked to Alzheimer's Disease and Its Comorbidities, and How Is It Prevented?

Impaired iron metabolism has been increasingly observed in many diseases, but a deeper, mechanistic understanding of the cellular impact of altered iron metabolism is still lacking. In addition, deficits in neuronal energy metabolism due to reduced glucose import were described for Alzheimer's disease (AD) and its comorbidities like obesity, depression, cardiovascular disease, and type 2 diabetes mellitus. The aim of this review is to present the molecular link between both observations. Insufficient cellular glucose uptake triggers increased ferritin expression, leading to depletion of the cellular free iron pool and stabilization of the hypoxia-induced factor (HIF) 1α. This transcription factor induces the expression of the glucose transporters (Glut) 1 and 3 and shifts the cellular metabolism towards glycolysis. If this first line of defense is not adequate for sufficient glucose supply, further reduction of the intracellular iron pool affects the enzymes of the mitochondrial electron transport chain and activates the AMP-activated kinase (AMPK). This enzyme triggers the translocation of Glut4 to the plasma membrane as well as the autophagic recycling of cell components in order to mobilize energy resources. Moreover, AMPK activates the autophagic process of ferritinophagy, which provides free iron urgently needed as a cofactor for the synthesis of heme- and iron-sulfur proteins. Excessive activation of this pathway ends in ferroptosis, a special iron-dependent form of cell death, while hampered AMPK activation steadily reduces the iron pools, leading to hypoferremia with iron sequestration in the spleen and liver. Long-lasting iron depletion affects erythropoiesis and results in anemia of chronic disease, a common condition in patients with AD and its comorbidities. Instead of iron supplementation, drugs, diet, or phytochemicals that improve energy supply and cellular glucose uptake should be administered to counteract hypoferremia and anemia of chronic disease.

Interferon-γ induces salivary gland epithelial cell ferroptosis in Sjogren's syndrome via JAK/STAT1-mediated inhibition of system Xc. Free Radic Biol Med 2023;205:116-128. [PMID: 37286044 DOI: 10.1016/j.freeradbiomed.2023.05.027]

The elevated level of interferon-γ (IFN-γ) in Sjogren's syndrome (SS) triggers salivary gland epithelial cells (SGEC) death. However, the underlying mechanisms of IFN-γ-induced SGEC death modes are still not fully elucidated. We found that IFN-γ triggers SGEC ferroptosis via Janus kinase/signal transducer and activator of transcription 1 (JAK/STAT1)-mediated inhibition of cystine-glutamate exchanger (System Xc-). Transcriptome analysis revealed that ferroptosis-related markers are differentially expressed in SS human and mouse salivary glands with distinct upregulation of IFN-γ and downregulation of glutathione peroxidase 4 (GPX4) and aquaporin 5 (AQP5). Inducing ferroptosis or IFN-γ treatment in the Institute of cancer research (ICR) mice aggravated and inhibition of ferroptosis or IFN-γ signaling in SS model non-obese diabetic (NOD) mice alleviated ferroptosis in the salivary gland and SS symptoms. IFN-γ activated STAT1 phosphorylation and downregulated system Xc- components solute carrier family 3 member 2 (SLC3A2), glutathione, and GPX4 thereby triggering ferroptosis in SGEC. JAK or STAT1 inhibition in SGEC rescued IFN-γ-downregulated SLC3A2 and GPX4 as well as IFN-γ-induced cell death. Our results indicate the role of ferroptosis in SS-related death of SGEC and SS pathogenicity.

Differences in Hepatocellular Iron Metabolism Underlie Sexual Dimorphism in Hepatocyte Ferroptosis

Males show higher incidence and severity than females in hepatic injury and many liver diseases, but the mechanisms are not well understood. Ferroptosis, an iron-mediated lipid peroxidation-dependent death, plays an important role in the pathogenesis of liver diseases. We determined whether hepatocyte ferroptosis displays gender difference, accounting for sexual dimorphism in liver diseases. Compared to female hepatocytes, male hepatocytes were much more vulnerable to ferroptosis by iron and pharmacological inducers including RSL3 and iFSP1. Male but not female hepatocytes exhibited significant increases in mitochondrial Fe 2+ and mitochondrial ROS (mtROS) contents. Female hepatocytes showed a lower expression of iron importer transferrin receptor 1 (TfR1) and mitochondrial iron importer mitoferrin 1 (Mfrn1), but a higher expression of iron storage protein ferritin heavy chain 1 (FTH1). It is well known that TfR1 expression is positively correlated with ferroptosis. Herein, we showed that silencing FTH1 enhanced while knockdown of Mfrn1 decreased ferroptosis in HepG2 cells. Removing female hormones by ovariectomy (OVX) did not dampen but rather enhanced hepatocyte resistance to ferroptosis. Mechanistically, OVX potentiated the decrease in TfR1 and increase in FTH1 expression. OVX also increased FSP1 expression in ERK-dependent manner. Elevation in FSP1 suppressed mitochondrial Fe 2+ accumulation and mtROS production, constituting a novel mechanism of FSP1-mediated inhibition of ferroptosis. In conclusion, differences in hepatocellular iron handling between male and female account, at least in part, for sexual dimorphism in induced ferroptosis of the hepatocytes.

Harnessing the Potential of Non-Apoptotic Cell Death Processes in the Treatment of Drug-Resistant Melanoma

Melanoma is a highly malignant skin cancer that is known for its resistance to treatments. In recent years, there has been significant progress in the study of non-apoptotic cell death, such as pyroptosis, ferroptosis, necroptosis, and cuproptosis. This review provides an overview of the mechanisms and signaling pathways involved in non-apoptotic cell death in melanoma. This article explores the interplay between various forms of cell death, including pyroptosis, necroptosis, ferroptosis, and cuproptosis, as well as apoptosis and autophagy. Importantly, we discuss how these non-apoptotic cell deaths could be targeted as a promising therapeutic strategy for the treatment of drug-resistant melanoma. This review provides a comprehensive overview of non-apoptotic processes and gathers recent experimental evidence that will guide future research and eventually the creation of treatment strategies to combat drug resistance in melanoma.

Liver specific disruption of Glutaredoxin 3 leads to iron accumulation and impaired cellular iron homeostasis

The role mammalian glutaredoxin 3 (Grx3) plays in iron homeostasis is poorly understood. Here we report the generation and characterization of a Grx3 liver-specific knockout (LKO) mouse strain. Grx3 LKO and WT mice had similar growth however, the LKO mice had elevated iron concentration and ROS production leading to impaired liver function and altered cytosolic and nuclear Fe-S cluster assembly. The expression of hepatic FTH1 and other iron homeostasis genes appeared to correlate with the elevation in iron concentration. Interestingly, this increase in hepatic FTH1 showed an inverse correlation with the abundance of autophagy pathway proteins. These findings suggest a crucial role for Grx3 in regulating hepatocyte iron homeostasis by controlling cellular storage protein turnover and recycling via the autophagy pathway.

Cross-talk between autophagy and ferroptosis contributes to the liver injury induced by fluoride via the mtROS-dependent pathway

Fluoride can induce hepatotoxicity, but the mechanisms responsible are yet to be investigated. This study sought to investigate the role and mechanism of mitochondrial reactive oxygen species (mtROS), autophagy, and ferroptosis in fluoride-induced hepatic injury with a focus on the role of mtROS-mediated cross-talk between autophagy and ferroptosis. To this end, an in vivo Sprague-Dawley rat model and in vitro BRL3A cells were exposed to sodium fluoride (NaF). The results revealed that NaF exposure diminished the mitochondrial membrane potential, increased mtROS production and TOMM20 expression, and induced autophagic flux blockage and ferroptosis in vivo and in vitro. Furthermore, the autophagy activator (RAPA) enhanced GPX4 expression while inhibiting ACSL4 expression, reduced the accumulation of ferrous ions in BRL3A cells, and restored lipid peroxidation levels, thus inhibiting ferroptosis. Fer-1, a ferritinase inhibitor, downregulated the expression of LC3-II and p62, increased the number of autolysosomes while decreasing the number of autophagosomes, and alleviated the blockage of autophagic flux by improving autophagic degradation. These results suggest the occurrence of a cross-talk between autophagy and ferroptosis. The mtROS inhibitor (Mito-TEMPO) could alleviate autophagic flux blockage and inhibit ferroptosis in NaF-induced liver injury. In addition, the cross-talk between NaF-induced autophagy and ferroptosis was dependent on the mtROS pathway.