Intracellular Iron Research Articles

Mitochondrial Fatty Acid Synthesis and Mecr Regulate CD4+ T Cell Function and Oxidative Metabolism.

Lipid metabolism is fundamental to CD4+ T cell metabolism yet remains poorly understood across subsets. Therefore, we performed targeted in vivo CRISPR/Cas9 screens to identify lipid-associated genes essential for T cell subset functions. These screens established mitochondrial fatty acid synthesis (mtFAS) genes Mecr, Mcat and Oxsm as highly impactful. Of these, the inborn error of metabolism gene Mecr was most dynamically regulated. Effector and memory T cells were reduced in Mecrfl/fl; Cd4cre mice, and MECR was required for activated CD4+ T cells to efficiently proliferate, differentiate, and survive. Mecr-deficient T cells also had decreased mitochondrial respiration, reduced TCA intermediates, and accumulated intracellular iron, which contributed to cell death and sensitivity to ferroptosis. Importantly, Mecr-deficient T cells exhibited fitness disadvantages in inflammatory, tumor, and infection models. mtFAS and MECR thus play important roles in activated T cells and may provide targets to modulate immune functions in inflammatory diseases. The immunological state of MECR- and mtFAS-deficient patients may also be compromised.

A global transcriptional activator involved in the iron homeostasis in cyanobacteria.

Cyanobacteria use a series of adaptation strategies and a complicated regulatory network to maintain intracellular iron (Fe) homeostasis. Here, a global activator named IutR has been identified through three-dimensional chromosome organization and transcriptome analysis in a model cyanobacterium Synechocystis sp. PCC 6803. Inactivation of all three homologous IutR-encoding genes resulted in an impaired tolerance of Synechocystis to Fe deficiency and loss of the responses of Fe uptake-related genes to Fe-deplete conditions. Protein-promoter interaction assays confirmed the direct binding of IutR with the promoters of genes related to Fe uptake, and chromatin immunoprecipitation sequencing analysis further revealed that in addition to Fe uptake, IutR could regulate many other physiological processes involved in intracellular Fe homeostasis. These results proved that IutR is an important transcriptional activator, which is essential for cyanobacteria to induce Fe-deficiency response genes. This study provides in-depth insights into the complicated Fe-deficient signaling network and the molecular mechanism of cyanobacteria adaptation to Fe-deficient environments.

Curcumin Induces Autophagy-mediated Ferroptosis by Targeting the PI3K/AKT/mTOR Signaling Pathway in Gastric Cancer.

As a very common malignancy of the digestive system, the incidence and mortality rates of gastric cancer (GC) are increasing year by year. The critical role of ferroptosis in cancer development has been well-documented. The polyphenol compound curcumin shows prominent anti-tumor effects in multiple cancer types, including GC. However, whether curcumin participates in GC tumorigenesis by regulating ferroptosis remains unknown. Gastric cancer cells AGS and HGC-27 were treated with curcumin (0, 10, and 20 μM). Cell viability and death were evaluated through CCK-8 and LDH release assays. LC3B expression in cells was estimated through immunofluorescence staining. Intracellular ferrous iron (Fe2+), GSH, MDA, and lipid ROS levels were assessed by corresponding assay kits. The cellular levels of autophagy markers (ATG5, ATG7, Beclin 1, and LC3B), ferroptosis markers (ACSL4, SLC7A11, and GPX4), and phosphorylated (p)-PI3K, p-AKT, and p-mTOR were determined through western blotting. Curcumin attenuated cell viability but stimulated cell death in GC cells. Curcumin enhanced autophagy in GC cells, as demonstrated by the increased levels of ATG5, ATG7, Beclin 1, and LC3B. Besides, curcumin upregulated iron, MDA, GSH, and ACSL4 levels while downregulated lipid ROS, SLC7A11, and GPX4 levels, suggesting its stimulation on ferroptosis in GC cells. Curcumin decreased p-PI3K, p-AKT, and p-mTOR levels in cells. Importantly, the ferroptosis inhibitor ferrostatin-1 overturned the impacts of curcumin on GC cell viability, death, and ferroptosis. Curcumin suppresses GC development by inducing autophagy-mediated ferroptosis by inactivating the PI3K/AKT/mTOR signaling.

ZnO NPs induce miR-342-5p mediated ferroptosis of spermatocytes through the NF-κB pathway in mice

BackgroundZinc oxide nanoparticle (ZnO NP) is one of the metal nanomaterials with extensive use in many fields such as feed additive and textile, which is an emerging threat to human health due to widely distributed in the environment. Thus, there is an urgent need to understand the toxic effects associated with ZnO NPs. Although previous studies have found accumulation of ZnO NPs in testis, the molecular mechanism of ZnO NPs dominated a decline in male fertility have not been elucidated.ResultsWe reported that ZnO NPs exposure caused testicular dysfunction and identified spermatocytes as the primary damaged site induced by ZnO NPs. ZnO NPs led to the dysfunction of spermatocytes, including impaired cell proliferation and mitochondrial damage. In addition, we found that ZnO NPs induced ferroptosis of spermatocytes through the increase of intracellular chelatable iron content and lipid peroxidation level. Moreover, the transcriptome analysis of testis indicated that ZnO NPs weakened the expression of miR-342-5p, which can target Erc1 to block the NF-κB pathway. Eventually, ferroptosis of spermatocytes was ameliorated by suppressing the expression of Erc1.ConclusionsThe present study reveals a novel mechanism in that miR-342-5p targeted Erc1 to activate NF-κB signaling pathway is required for ZnO NPs-induced ferroptosis, and provide potential targets for further research on the prevention and treatment of male reproductive disorders related to ZnO NPs.Graphical

The formation of lamellar body-like structures may be a trigger of cetylpyridinium chloride-induced cell death and inflammatory response

Cetylpyridinium chloride (CPC) is a quaternary ammonium compound used widely in health and personal care products. Meanwhile, due to its increasing use, its potential adverse health effects are emerging as a topic of public concern. In this study, we first administered CPC by pharyngeal aspiration to determine the survival level (the maximum concentration at which no death is observed) and then administered CPC to mice repeatedly for 28 days using the survival level as the highest concentration. CPC increased the total number of pulmonary cells secreting pro- and anti-inflammatory cytokines and chemokines. Infiltration of inflammatory cells, production of foamy alveolar macrophages, and chronic inflammatory lesions were found in the lung tissue of male and female mice exposed to the highest dose of CPC. We also investigated the toxicity mechanism using BEAS-2B cells isolated from normal human bronchial epithelium. At 6 h after exposure to CPC, the cells underwent non-apoptotic cell death, especially at concentrations greater than 2 μg/mL. The expression of the transferrin receptor was remarkably enhanced, and the expression of proteins that contribute to intracellular iron storage was inhibited. The expression of both mitochondrial SOD and catalase increased with CPC concentration, and PARP protein was cleaved, suggesting possible DNA damage. In addition, the internal structure of mitochondria was disrupted, and fusion between damaged organelles was observed in the cytoplasm. Most importantly, lamellar body-like structures and autophagosome-like vacuoles were found in CPC-treated cells, with enhanced expression of ABCA3 protein, a marker for lamellar body, and a docking score between ABCA3 protein and CPC was considered to be approximately −6.8969 kcal/mol. From these results, we propose that mitochondrial damage and iron depletion may contribute to CPC-induced non-apoptotic cell death and that pulmonary accumulation of cell debris may be closely associated with the inflammatory response. Furthermore, we hypothesize that the formation of lamellar body-like structures may be a trigger for CPC-induced cell death.

Ginsenoside RK1 Induces Ferroptosis in Hepatocellular Carcinoma Cells through an FSP1-Dependent Pathway.

Hepatocellular carcinoma (HCC), currently ranking as the third most lethal malignancy, poses a grave threat to human health. Ferroptosis, a form of programmed cell demise, has emerged as a promising therapeutic target in HCC treatment. In this study, we investigated the impact of ginsenoside RK1 on ferroptosis induction in HCC cells and elucidated the underlying mechanisms. The HCC cell line HepG2 was utilized to evaluate the effects of ginsenoside RK1. Distinct dosages of ginsenoside RK1 (25 μM, 50 μM, and 100 μM) were selected based on half-maximal inhibitory concentration (IC50) values. Cellular viability was assessed using a CCK8 assay, cytotoxicity was measured via lactate dehydrogenase (LDH) release assay, and colony-forming ability was evaluated using the clone formation assay. Various inhibitors targeting apoptosis (Z-VAD-FMK 20 μM), necrosis (Nec-1, 10 μM), and ferroptosis (Fer-1, 10 μM; Lip-1, 1 μM) were employed to assess ginsenoside RK1's impact on cell demise. Intracellular levels of key ions, including glutathione (GSH), malondialdehyde (MDA), and iron ions, were quantified, and the protein expression levels of ferroptosis-related genes were evaluated. The sensitivity of HCC cells to ferroptosis induction by ginsenoside RK1 was examined following the overexpression and silencing of the aforementioned target genes. Ginsenoside RK1 exhibited an inhibitory effect on HCC cells with an IC50 value of approximately 20 μM. It attenuated cellular viability and colony-forming capacity in a dose-dependent manner, concurrently reducing intracellular GSH levels and increasing intracellular Malondialdehyde (MDA) and iron ion contents. Importantly, cell demise induced by ginsenoside RK1 was specifically counteracted by ferroptosis inhibitors. Furthermore, the modulation of Ferroptosis suppressor protein 1 (FSP1) expression influenced the ability of ginsenoside RK1 to induce ferroptosis. FSP1 overexpression or silencing enhanced or inhibited ferroptosis induction by ginsenoside RK1, respectively. Ginsenoside RK1 enhances ferroptosis in hepatocellular carcinoma through an FSP1-dependent pathway.

Targeting Ferroptosis: A Novel Strategy for the Treatment of Atherosclerosis.

Since ferroptosis was reported in 2012, its application prospects in various diseases have been widely considered, initially as a treatment direction for tumors. Recent studies have shown that ferroptosis is closely related to the occurrence and development of atherosclerosis. The primary mechanism is to affect the occurrence and development of atherosclerosis through intracellular iron homeostasis, ROS and lipid peroxide production and metabolism, and a variety of intracellular signaling pathways. Inhibition of ferroptosis is effective in inhibiting the development of atherosclerosis, and it can bring a new direction for treating atherosclerosis. In this review, we discuss the mechanism of ferroptosis and focus on the relationship between ferroptosis and atherosclerosis, summarize the different types of ferroptosis inhibitors that have been widely studied, and discuss some issues worthy of attention in the treatment of atherosclerosis by targeting ferroptosis.

TRPML1 triggers ferroptosis defense and is a potential therapeutic target in AKT-hyperactivated cancer.

Targeting ferroptosis for cancer therapy has slowed because of an incomplete understanding of ferroptosis mechanisms under specific pathological contexts such as tumorigenesis and cancer treatment. Here, we identify TRPML1-mediated lysosomal exocytosis as a potential anti-ferroptotic process through genome-wide CRISPR-Cas9 activation and kinase inhibitor library screening. AKT directly phosphorylated TRPML1 at Ser343 and inhibited K552 ubiquitination and proteasome degradation of TRPML1, thereby promoting TRPML1 binding to ARL8B to trigger lysosomal exocytosis. This boosted ferroptosis defense of AKT-hyperactivated cancer cells by reducing intracellular ferrous iron and enhancing membrane repair. Correlation analysis and functional analysis revealed that TRPML1-mediated ferroptosis resistance is a previously unrecognized feature of AKT-hyperactivated cancers and is necessary for AKT-driven tumorigenesis and cancer therapeutic resistance. TRPML1 inactivation or blockade of the interaction between TRPML1 and ARL8B inhibited AKT-driven tumorigenesis and cancer therapeutic resistance in vitro and in vivo by promoting ferroptosis. A synthetic peptide targeting TRPML1 inhibited AKT-driven tumorigenesis and enhanced the sensitivity of AKT-hyperactivated tumors to ferroptosis inducers, radiotherapy, and immunotherapy by boosting ferroptosis in vivo. Together, our findings identified TRPML1 as a therapeutic target in AKT-hyperactivated cancer.

N-rich carbon nanosphere as fluorescent nanoprobe for intracellular iron

Nitrogen rich carbon nanoparticles are known to provide higher fluorescence stokes shift, and thereby are potential candidates for fluorescent sensors. Herein, a facile one-step hydrothermal synthesis is reported for N-rich carbon nanospheres (G-CNS) from caffeine and o-phenylenediamine as precursors. The as-synthesized G-CNS showed high fluorescence with λem at 509 nm, with a highly selective fluorescence turn-off response towards Fe2+/Fe3+, rendering these carbon nanospheres as potential candidates to detect intracellular labile iron pool in live cells. The intracellular labile iron pool in iron-overloaded cells was sensed using the synthesized G-CNS. Mechanistically, the fluorescence quenching via dynamic pathway involves the formation of an excited state charge transfer process, which undergoes non-radiative decay.

Intravenous iron therapy results in rapid and sustained rise in myocardial iron content through a novel pathway.

Intravenous iron therapies contain iron-carbohydrate complexes, designed to ensure iron becomes bioavailable via the intermediary of spleen and liver reticuloendothelial macrophages. How other tissues obtain and handle this iron remains unknown. This study addresses this question in the context of the heart. A prospective observational study was conducted in 12 patients receiving ferric carboxymaltose (FCM) for iron deficiency. Myocardial, spleen, and liver magnetic resonance relaxation times and plasma iron markers were collected longitudinally. To examine the handling of iron taken up by the myocardium, intracellular labile iron pool (LIP) was imaged in FCM-treated mice and cells. In patients, myocardial relaxation time T1 dropped maximally 3 h post-FCM, remaining low 42 days later, while splenic T1 dropped maximally at 14 days, recovering by 42 days. In plasma, non-transferrin-bound iron (NTBI) peaked at 3 h, while ferritin peaked at 14 days. Changes in liver T1 diverged among patients. In mice, myocardial LIP rose 1 h and remained elevated 42 days after FCM. In cardiomyocytes, FCM exposure raised LIP rapidly. This was prevented by inhibitors of NTBI transporters T-type and L-type calcium channels and divalent metal transporter 1. Intravenous iron therapy with FCM delivers iron to the myocardium rapidly through NTBI transporters, independently of reticuloendothelial macrophages. This iron remains labile for weeks, reflecting the myocardium's limited iron storage capacity. These findings challenge current notions of how the heart obtains iron from these therapies and highlight the potential for long-term dosing to cause cumulative iron build-up in the heart.

The miR-182-5p/GPX4 Pathway Contributes to Sevoflurane-Induced Ototoxicity via Ferroptosis.

Our study aimed to investigate the role of ferroptosis in sevoflurane-induced hearing impairment and explore the mechanism of the microRNA-182-5p (miR-182-5p)/Glutathione Peroxidase 4 (GPX4) pathway in sevoflurane-induced ototoxicity. Immunofluorescence staining was performed using myosin 7a and CtBP2. Cell viability was assessed using the CCK-8 kit. Fe2+ concentration was measured using FerroOrange and Mi-to-FerroGreen fluorescent probes. The lipid peroxide level was assessed using BODIPY 581/591 C11 and MitoSOX fluorescent probes. The auditory brainstem response (ABR) test was conducted to evaluate the hearing status. Bioinformatics tools and dual luciferase gene reporter analysis were used to confirm the direct targeting of miR-182-5p on GPX4 mRNA. GPX4 and miR-182-5p expression in cells was assessed by qRT-PCR and Western blot. Ferrostatin-1 (Fer-1) pretreatment significantly improved hearing impairment and damage to ribbon synapses in mice caused by sevoflurane exposure. Immunofluorescence staining revealed that Fer-1 pretreatment reduced intracellular and mitochondrial iron overload, as well as lipid peroxide accumulation. Our findings indicated that miR-182-5p was upregulated in sevoflurane-exposed HEI-OC1 cells, and miR-182-5p regulated GPX4 expression by binding to the 3'UTR of GPX4 mRNA. The inhibition of miR-182-5p attenuated sevoflurane-induced iron overload and lipid peroxide accumulation. Our study elucidated that the miR-182-5p/GPX4 pathway was implicated in sevoflurane-induced ototoxicity by promoting ferroptosis.

Biological characteristics of manganese transporter MntP in Klebsiella pneumoniae.

Klebsiella pneumoniae is an important opportunistic pathogen that causes a variety of infections. It is critical for bacteria to maintain metal homeostasis during infection. By using an isogenic mntP deletion mutant of K. pneumoniae strain NTUH-K2044, we found that MntP was a manganese efflux pump. Manganese increased the tolerance to oxidative stress, and oxidative stress could increase the intracellular manganese concentration. In oxidative stress, the mntP deletion mutant exhibited significantly higher sensitivity to manganese. Furthermore, iron could increase the tolerance of the mntP deletion mutant to manganese. Inductively coupled plasma mass spectrometry analysis revealed that the mntP deletion mutant had higher intracellular manganese and iron concentrations than wild-type and complementary strains. These findings suggested that iron could increase manganese tolerance in K. pneumoniae. This work elucidated the role of MntP in manganese detoxification and Mn/Fe homeostasis in K. pneumoniae.IMPORTANCEMetal homeostasis plays an important role during the process of bacterial infection. Herein, we revealed that MntP was involved in intracellular manganese homeostasis. Manganese promoted resistance to oxidative stress in Klebsiella pneumoniae. Furthermore, we demonstrated that the mntP deletion mutant exhibited significantly lower survival under manganese and H2O2 conditions. Oxidative stress increased the intracellular manganese content of the mntP deletion mutant. MntP played a critical role in maintaining intracellular manganese and iron concentrations. MntP contributed to manganese detoxification and Mn/Fe homeostasis in K. pneumoniae.

Recent Progress of Glutathione Peroxidase 4 Inhibitors in Cancer Therapy.

Ferroptosis is a novel type of programmed cell death that relies on the build-up of intracellular iron and leads to an increase in toxic lipid peroxides. Glutathione Peroxidase 4 (GPX4) is a crucial regulator of ferroptosis that uses glutathione as a cofactor to detoxify cellular lipid peroxidation. Targeting GPX4 in cancer could be a promising strategy to induce ferroptosis and kill drugresistant cancers effectively. Currently, research on GPX4 inhibitors is of increasing interest in the field of anti-tumor agents. Many reviews have summarized the regulation and ferroptosis induction of GPX4 in human cancer and disease. However, insufficient attention has been paid to GPX4 inhibitors. This article outlines the molecular structures and development prospects of GPX4 inhibitors as novel anticancer agents.

Excessive autophagy of myocardial cells promotes ferroptosis and exacerbates heart failure in the state of myocardial infarction

IntroductionThis study investigates the molecular mechanisms by which excessive autophagy exacerbates post-myocardial infarction heart failure(post-MI HF) through nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy and ferroptosis.Material and methodsWe developed a post-MI heart failure model in Sprague-Dawley rats via coronary artery ligation, alongside an in vitro heart failure model using hypoxia/reoxygenation-stimulated H9C2 cells. Intervention with rapamycin (autophagy activator), 3-methyladenine (autophagy inhibitor), desferrioxamine, and ferredoxin-1(ferroptosis inhibitors). Various techniques, including echocardiography, immunofluorescence colocalization, C11 BODIPY 581/591 staining, flow cytometry, transmission electron microscopy, western blotting, and RT-qPCR, were employed.ResultsIn vivo analyses revealed that NCOA4-mediated ferritinophagy and ferroptosis are significant in post-MI HF. Manipulating autophagy through rapamycin and 3-methyladenine influenced the expression of NCOA4 and glutathione peroxidase 4 (GPX4), subsequently affecting ferroptosis and modulating heart failure severity. Our in vitro experiments corroborated these findings, demonstrating that heightened autophagy amplifies NCOA4 expression, which in turn fosters ferroptosis and exacerbates myocardial injury. Interestingly, silencing of NCOA4 partially mitigated autophagy-induced iron deficiency, indicating a crucial intersection between autophagy and iron metabolism. Moreover, the cardioprotective effects observed following NCOA4 silencing were negated by concurrent GPX4 silencing.ConclusionsOur findings elucidate that autophagy precedes NCOA4 in its regulatory pathway and directly influences ferritinophagy. Enhanced autophagy augments intracellular free iron and unstable iron pools, triggering lipid peroxidation through ferritinophagy, which promotes ferroptosis and impairs cardiac function. These insights offer a novel scientific basis for developing therapeutic strategies for heart failure post-MI HF.

Diquat causes mouse testis injury through inducing heme oxygenase-1-mediated ferroptosis in spermatogonia

Diquat dibromide (DQ) is a globally used herbicide in agriculture, and its overuse poses an important public health issue, including male reproductive toxicity in mammals. However, the effects and molecular mechanisms of DQ on testes are limited. In vivo experiments, mice were intraperitoneally injected with 8 or 10 mg/kg/ day of DQ for 28 days. It has been found that heme oxygenase-1 (HO-1) mediates DQ-induced ferroptosis in mouse spermatogonia, thereby damaging testicular development and spermatogenesis. Histopathologically, we found that DQ exposure caused seminiferous tubule disorders, reduced germ cells, and increased sperm malformation, in mice. Reactive oxygen species (ROS) staining of frozen section and transmission electron microscopy (TEM) displayed DQ promoted ROS generation and mitochondrial morphology alterations in mouse testes, suggesting that DQ treatment induced testicular oxidative stress. Subsequent RNA-sequencing further showed that DQ treatment might trigger ferroptosis pathway, attributed to disturbed glutathione metabolism and iron homeostasis in spermatogonia cells in vitro. Consistently, results of western blotting, measurements of MDA and ferrous iron, and ROS staining confirmed that DQ increased oxidative stress and lipid peroxidation, and accelerated ferrous iron accumulation both in vitro and in vivo. Moreover, inhibition of ferroptosis by deferoxamine (DFO) markedly ameliorated DQ-induced cell death and dysfunction. By RNA-sequencing, we found that the expression of HO-1 was significantly upregulated in DQ-treated spermatogonia, while ZnPP (a specific inhibitor of HO-1) blocked spermatogonia ferroptosis by balancing intracellular iron homeostasis. In mice, administration of the ferroptosis inhibitor ferrostatin-1 effectively restored the increase of HO-1 levels in the spermatogonia, prevented spermatogonia death, and alleviated the spermatogenesis disorders induced by DQ. Overall, these findings suggest that HO-1 mediates DQ-induced spermatogonia ferroptosis in mouse testes, and targeting HO-1 may be an effective protective strategy against male reproductive disorders induced by pesticides in agriculture.

Epigallocatechin gallate modulates ferroptosis through downregulation of tsRNA-13502 in non-small cell lung cancer

Ferroptosis, an iron-dependent regulated cell death mechanism, holds significant promise as a therapeutic strategy in oncology. In the current study, we explored the regulatory effects of epigallocatechin gallate (EGCG), a prominent polyphenol in green tea, on ferroptosis and its potential therapeutic implications for non-small cell lung cancer (NSCLC). Treatment of NSCLC cell lines with varying concentrations of EGCG resulted in a notable suppression of cell proliferation, as evidenced by a reduction in Ki67 immunofluorescence staining. Western blot analyses demonstrated that EGCG treatment led to a decrease in the expression of glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11) while increasing the levels of acyl-CoA synthetase long-chain family member 4 (ACSL4). These molecular changes were accompanied by an increase in intracellular iron, malondialdehyde (MDA), and reactive oxygen species (ROS), alongside ultrastructural alterations characteristic of ferroptosis. Through small RNA sequencing and RT-qPCR, transfer RNA-derived small RNA 13502 (tsRNA-13502) was identified as a significant target of EGCG action, with its expression being upregulated in NSCLC tissues compared to adjacent non-tumorous tissues. EGCG was found to modulate the ferroptosis pathway by downregulating tsRNA-13502 and altering the expression of key ferroptosis regulators (GPX4/SLC7A11 and ACSL4), thereby promoting the accumulation of iron, MDA, and ROS, and ultimately inducing ferroptosis in NSCLC cells. This study elucidates EGCG’s multifaceted mechanisms of action, underscoring the modulation of ferroptosis as a viable therapeutic approach for enhancing NSCLC treatment outcomes.

Phosphorylated FOXQ1, a novel substrate of JNK1, inhibits sorafenib-induced ferroptosis by activating ETHE1 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly heterogeneous and malignant cancer with poor overall survival. The application of sorafenib is a major breakthrough in the treatment of HCC. In our study, FOXQ1 was significantly overexpressed in sorafenib-resistant HCC cells and suppressed sorafenib-induced ferroptosis. We found that phosphorylation of FOXQ1 at serine 248 is critical for the suppression of sorafenib-induced ferroptosis. Furthermore, as the upstream phosphorylation kinase of FOXQ1, JNK1, which is activated by sorafenib, can directly phosphorylate the serine 248 site of FOXQ1. Then, the phosphorylated FOXQ1 got a high affinity for the promoter of ETHE1 and activates its transcription. Further flow cytometry results showed that ETHE1 reduced intracellular lipid peroxidation and iron levels. Collectively, our study implicated the JNK1-FOXQ1-ETHE1 axis in HCC ferroptosis induced by sorafenib, providing mechanistic insight into sensitivity to sorafenib therapy of HCC.

Chemical screen in zebrafish lateral line identified compounds that ameliorate neomycin-induced ototoxicity by inhibiting ferroptosis pathway

BackgroundOtotoxicity is a major side effect of many broadly used aminoglycoside antibiotics (AGs) and no FDA-approved otoprotective drug is available currently. The zebrafish has recently become a valuable model to investigate AG-induced hair cell toxicity and an expanding list of otoprotective compounds that block the uptake of AGs have been identified from zebrafish-based screening; however, it remains to be established whether inhibiting intracellular cell death pathway(s) constitutes an effective strategy to protect against AG-induced ototoxicity.ResultsWe used the zebrafish model as well as in vitro cell-based assays to investigate AG-induced cell death and found that ferroptosis is the dominant type of cell death induced by neomycin. Neomycin stimulates lipid reactive oxygen species (ROS) accumulation through mitochondrial pathway and blocking mitochondrial ferroptosis pathway effectively protects neomycin-induced cell death. We screened an alkaloid natural compound library and identified seven small compounds that protect neomycin-induced ototoxicity by targeting ferroptosis pathway: six of them are radical-trapping agents (RTAs) while the other one (ellipticine) regulates intracellular iron homeostasis, which is essential for the generation of lipid ROS to stimulate ferroptosis.ConclusionsOur study demonstrates that blocking intracellular ferroptosis pathway is an alternative strategy to ameliorate neomycin-induced ototoxicity and provides multiple hit compounds for further otoprotective drug development.

Sappanone a alleviates osteoarthritis progression by inhibiting chondrocyte ferroptosis via activating the SIRT1/Nrf2 signaling pathway.

Osteoarthritis (OA) is a common degenerative joint disease that cause pain and disability in adults. Chondrocyte ferroptosis is found to be involved in OA progression. Sappanone A has been found as an anti-inflammatory and antioxidative agent in several diseases. This study aims to investigate the effects of sappanone A on OA progression and chondrocyte ferroptosis.IL-1β-induced chondrocytes and destabilization of the medial meniscus (DMM)-induced rats were respectively used as the OA model in vitro and in vivo. The effects of sappanone A on inflammation, extracellular matrix (ECM) metabolism, and ferroptosis were determined.Our results showed thatin IL-1β-induced chondrocytes, sappanone A suppressed the production of NO, PGE2, TNF-α, IL-6, iNOS, and COX2. Sappanone A also inhibited the expression of MMP3, MMP13, and ADAMTS5, while increasing collagen II expression. Moreover, sappanone A alleviated cytotoxicity and decreased the levels of intracellular ROS, lipid ROS, MDA, and iron, while increasing GSH levels. Additionally, sappanone A increased the protein expression of SLC7A11 and GPX4. Administration of ferroptosis activator reversed the inhibitory effects of sappanone A on IL-1β-induced inflammation and ECM degradation. More importantly, Sappanone A activated the Nrf2 signaling by targeting SIRT1. The inhibition of sappanone A on ferroptosis was greatly eliminated due to the addition of SIRT1 inhibitor. Furthermore, intra-articular injection of sappanone A mitigated cartilage destruction and ferroptosis in DMM-induced OA rats.In conclusion,sappanone A protects against inflammation and ECM degradation in OA via decreasing chondrocyte ferroptosis by activating the SIRT1/Nrf2 signaling. These findings deepen our understanding of chondrocyte ferroptosis in OA and highlight the therapeutic potential of sappanone A for OA.

Iron efflux by IetA enhances β-lactam aztreonam resistance and is linked to oxidative stress through cellular respiration in Riemerella anatipestifer.

Riemerella anatipestifer encodes an iron acquisition system, but whether it encodes the iron efflux pump and its role in antibiotic resistance are largely unknown. To screen and identify an iron efflux gene in R. anatipestifer and determine whether and how the iron efflux gene is involved in antibiotic resistance. In this study, gene knockout, streptonigrin susceptibility assay and inductively coupled plasma mass spectrometry were used to screen for the iron efflux gene ietA. The MIC measurements, scanning electron microscopy and reactive oxygen species (ROS) detection were used to verify the role of IetA in aztreonam resistance and its mechanism. Mortality and colonization assay were used to investigate the role of IetA in virulence. The deletion mutant ΔietA showed heightened susceptibility to streptonigrin, and prominent intracellular iron accumulation was observed in ΔfurΔietA under excess iron conditions. Additionally, ΔietA exhibited increased sensitivity to H2O2-produced oxidative stress. Under aerobic conditions with abundant iron, ΔietA displayed increased susceptibility to the β-lactam antibiotic aztreonam due to heightened ROS production. However, the killing efficacy of aztreonam was diminished in both WT and ΔietA under anaerobic or iron restriction conditions. Further experiments demonstrated that the efficiency of aztreonam against ΔietA was dependent on respiratory complexes Ⅰ and Ⅱ. Finally, in a duckling model, ΔietA had reduced virulence compared with the WT. Iron efflux is critical to alleviate oxidative stress damage and β-lactam aztreonam killing in R. anatipestifer, which is linked by cellular respiration.