Intracellular Iron Accumulation Research Articles

Chorein deficiency promotes ferroptosis.

Ferroptosis is a type of programmed cell death owed to an intracellular accumulation of iron resulting in the generation reactive oxygen species, which in turn can cause peroxidation of plasma membrane lipids and ultimately result in cell death. We investigated the potential involvement of VPS13A deficiency in ferroptosis. The VPS13A gene encodes for chorein, and its deficiency is a molecular cause of chorea-acanthocytosis (ChAc), a Huntington-like disease with neurodegeneration in the striatum. In our previous study, we found male infertility characterized by increased malondialdehyde staining of the spermatozoa in the testes of the ChAc model mice. Thus, in this study we performed metabolome analysis of sperm extracted from the epididymis of the ChAc model mice, which revealed decreased cystine levels, suggesting an association between chorein deficiency and ferroptosis. We then investigated the role of chorein in ferroptosis using VPS13A knockdown (VPS13A-KD) HEK293 cells. We found that VPS13A-KD cells displayed a significantly diminished resistance to tert-Butyl hydroperoxide (tBHP)-induced lipid peroxidation and cell death compared to control cells, which could be rescued by treatment with ferrostatin-1. Moreover, VPS13A-KD cells showed Fe(II) accumulation, suggesting an impaired capacity for divalent iron removal. In the cytosolic fraction of VPS13A-KD cells, the protein level of glutathione peroxidase 4 (GPX4) was significantly reduced, suggesting that dysfunction of chorein impairs GPX4 transport, thereby facilitating ferroptosis. These results suggest that ferroptosis may contribute to neurodegeneration in ChAc caused by loss of chorein function.

Tetrahedral framework nucleic acids inhibit Aβ-mediated ferroptosis and ameliorate cognitive and synaptic impairments in Alzheimer’s disease

BackgroundFerroptosis represents a nonapoptotic type of programmed cell death induced by excessive intracellular iron accumulation. Ferroptosis is an essential driver of the pathogenesis of Alzheimer’s disease (AD). Tetrahedral framework nucleic acids (tFNAs) are a novel type of nanoparticle with superior antiapoptotic capacity and excellent biocompatibility. However, the effect of tFNAs on Aβ triggered ferroptosis, cognitive and synaptic impairments in AD remains unknown.MethodsN2a cells were treated with Aβ combined with/without tFNAs. Cell viability and levels of Fe2+, lipid peroxidation, MDA, LDH, and GSH were examined. RNA sequencing was applied to explore dysregulated ferroptosis related genes. Seven-month-old APP/PS1 mice were intranasally administrated with tFNAs for two weeks. Fluorescence imaging was used to detect the tFNAs distribution in the brain. Novel object recognition (NOR) test followed by Morris water maze (MWM) was used to test the learning and memory performance of mice. Golgi staining, Western blot, and immunofluorescence staining were used to examine synaptic plasticity.ResultstFNAs promoted cell viability and GSH levels, reduced the levels of Fe2+, lipid peroxidation, MDA, and LDH in N2a cells treated with Aβ. RNA sequencing revealed that tFNAs reversed the promotive effect of Aβ on ferroptosis driver Atf3 gene and suppressive effect on ferroptosis suppressors Rrm2 and Furin genes. Fluorescence imaging confirmed the brain infiltration of tFNAs. tFNAs rescued synaptic and memory impairments, and ferroptosis in seven-month-old APP/PS1 mice.ConclusionsCollectively, tFNAs inhibited Aβ-mediated ferroptosis and ameliorated cognitive and synaptic impairments in AD mice. tFNAs may serve as novel option to deal with AD.Graphical abstract

Chiisanoside from the Leaves of Acanthopanax sessiliflorus Can Resist Cisplatin-Induced Ototoxicity by Maintaining Cytoskeletal Homeostasis and Inhibiting Ferroptosis.

Ototoxicity is a common side effect of cisplatin cancer treatment, potentially leading to hearing loss. This study demonstrated the significant protective activity of Acanthopanax sessiliflorus (A. sessiliflorus) leaves against cisplatin-induced ototoxicity (CIO), investigated the active compounds, and elucidated their mechanisms in countering CIO. UPLC-Q/TOF-MS analysis identified 79 compounds. Network pharmacology and activity screening determined that chiisanoside (CSS) plays a crucial role in combating CIO. Transcriptomics combined with network pharmacology analysis and experiments revealed that CSS activates the Dock1/PIP5K1A pathway to suppress the actin-severing protein gelsolin, protecting hair cells from cisplatin-induced cytoskeleton damage. CSS also activates the SLC7A11/GPX4 pathway via TGFBR2, reducing lipid peroxidation and intracellular iron accumulation to suppress cisplatin-induced ferroptosis. This study discovers that the major component CSS in A. sessiliflorus leaves reverses CIO by regulating actin homeostasis via Dock1 and inhibiting ferroptosis through TGFBR2, providing a theoretical basis for expanding CIO treatment targets and related drug development.

Development of oxidative stress- and ferroptosis-related prognostic signature in gastric cancer and identification of CDH19 as a novel biomarker

BackgroundFerroptosis is a unique mode of cell death that is iron-dependent and associated with oxidative stress and lipid peroxidation. Oxidative stress and ferroptosis are essential mechanisms leading to metabolic abnormalities in cells and have been popular areas in cancer research.MethodsInitially, 76 oxidative stress and ferroptosis-related genes (OFRGs) were acquired by intersecting the gene sets from oxidative stress and ferroptosis. Afterwards, optimal OFRGs were screened using PPI networks, and individuals were separated into two OFRG subtypes (K = 2). Subsequently, we successfully constructed and verified a prognostic signature comprising SLC7A2, Cadherin 19 (CDH19), and CCN1. To further uncover potential biomarkers of gastric cancer (GC), we examined the expression level of CDH19, investigated the effects of knocking down CDH19 on the biological behavior of GC cells, and explored whether CDH19 is involved in ferroptosis and oxidative stress processes.ResultsAccording to the findings, individuals in the low-risk scoring group have less infiltration of immune suppressive cells, fewer occurrences of immune escape and dysfunction, greater efficacy in chemotherapy and immunotherapy, and better survival outcomes. The qRT-PCR assay indicated that CDH19 expression was significantly higher in GC cells. Through experiments, we demonstrated that knocking down CDH19 can affect the transcription levels of ACSL4 and GPX4, increase intracellular iron ion concentration and accumulation of reactive oxygen species (ROS), and inhibit the proliferation and migration of GC cells.ConclusionWe developed an OFRG-related signature to predict the prognosis and treatment responsiveness of individuals with GC and identified CDH19 as a possible therapeutic target for GC.

Biochanin A inhibits excitotoxicity-triggered ferroptosis in hippocampal neurons

Excitatory neurotransmitter-induced neuronal ferroptosis has been implicated in multiple neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease. Although there are several reports pertaining to the pharmacological activities of biochanin A, the effects of this isoflavone on excitotoxicity-triggered neuronal ferroptosis remain unclear. In this study, we demonstrate that biochanin A inhibits ferroptosis of mouse hippocampal neurons induced by glutamate or the glutamate analog, kainic acid. Biochanin A significantly inhibited accumulation of intracellular iron and lipid peroxidation in glutamate- or kainic acid-treated mouse hippocampal neurons. Furthermore, biochanin A regulated the level of glutathione peroxidase 4, a master regulator of ferroptosis, by modulating its autophagy-dependent degradation. We observed that biochanin A reduced the glutamate-induced accumulation of intracellular iron by regulating expression of iron metabolism-related proteins including ferroportin-1, divalent metal transferase 1, and transferrin receptor 1. Taken together, these results indicate that biochanin A effectively inhibits hippocampal neuronal death triggered by glutamate or kainic acid. Our study is the first to report that biochanin A has therapeutic potential for the treatment of diseases associated with hippocampal neuronal death, particularly ferroptosis induced by excitatory neurotransmitter.

Overexpression of Nfs1 Cysteine Desulphurase Relieves Sevoflurane-Induced Neurotoxicity and Cognitive Dysfunction in Neonatal Mice Via Suppressing Oxidative Stress and Ferroptosis.

Clinical evidence suggests that multiple exposures to sevoflurane in young people may be detrimental to cognitive development. Iron accumulation in the hippocampus is associated with sevoflurane-induced neurotoxicity and cognitive deficits. The cysteine desulphurase, Nfs1, the rate-limiting enzyme for the biosynthesis of iron-sulphur clusters, plays a role in cellular iron homeostasis. However, the impact of Nfs1-mediated ferroptosis on sevoflurane-induced neurotoxicity and cognitive impairments in neonatal mice remains undetermined. Neonatal mice at postnatal Day 6 received 3% sevoflurane daily for 3 consecutive days. Cognitive function was assessed using the Morris water maze test, and neurotoxicity was evaluated through terminal deoxynucleotidyl transferase dUTP nick end labeling and immunofluorescence staining. Here, HT22 hippocampal neurons were employed for in-vitro experiments, and Fe2+ accumulation was measured. Ferroptosis-related genes, including glutathione peroxidase 4 (GPX4), transferrin receptor 1 (TFR1) and ferritin, in the hippocampus and HT22 cells were observed, along with oxidative stress-related indicators such as reactive oxygen species (ROS), methionine adenosyltransferase (MAT), glutathione (GSH) and lipid peroxidation (LPO). Transmission electron microscopy was utilized to examine the mitochondrial microstructure. Sevoflurane exposure significantly decreased Nfs1 expression in the hippocampus of mice and HT22 cells. This exposure resulted in cognitive impairments and neuronal damage in the hippocampus, which were alleviated by overexpression of Nfs1. Intracellular and mitochondrial iron accumulation occurred in HT22 cells following sevoflurane treatment. Sevoflurane exposure also significantly reduced GSH levels and increased levels of malondialdehyde, ROS and LPO in the hippocampus or HT22 cells. Additionally, sevoflurane exposure decreased GPX4 expression but increased TFR1 and ferritin expression in the hippocampus or HT22 cells. Overexpression of Nfs1 reversed the sevoflurane-induced alterations in ferroptosis-related genes and oxidative stress-related indicators. Furthermore, overexpression of Nfs1 alleviated sevoflurane-induced mitochondrial dysfunction. However, Nfs1 knockdown alone did not result in cognitive impairments, ferroptosis or oxidative stress. The overexpression of Nfs1 mitigated sevoflurane-induced neurotoxicity and cognitive impairment by modulating oxidative stress and ferroptosis through the regulation of iron metabolism and transport.

Increased calcification by erythrophagocytosis in aortic valvular interstitial cells.

Calcific aortic valve disease (CAVD) progresses over time to severe aortic stenosis and eventually heart failure. Recent evidence indicates that intraleaflet haemorrhage (ILH) strongly promotes CAVD progression. However, it remains poorly understood how it mechanistically contributes to valvular calcification. ILH was identified as iron deposition by morphological analysis. To elucidate the underlying mechanism, human valvular interstitial cells (VIC) were cultured in the presence of fresh or senescent red blood cells (RBC), simulating ILH in vivo conditions. ILH was common in aortic valves derived from patients with severe aortic stenosis. VIC undergo erythrophagocytosis of senescent RBC, leading to intracellular iron accumulation analogous to observed following exposure to extracellular iron. The presence of senescent RBC significantly intensified VIC calcification, which was significantly mitigated by ferroptosis inhibition. Our results identify erythrophagocytosis by VIC, leading to iron accumulation and enhanced calcification through ferroptosis. This may be a crucial component of the pathophysiological mechanisms that links ILH to valvular calcification and accelerated aortic stenosis progression.

Metformin suppresses metabolic dysfunction-associated fatty liver disease by ferroptosis and apoptosis via activation of oxidative stress

Metformin is known for its antioxidant properties and ability to ameliorate metabolic dysfunction-associated fatty liver disease (MAFLD) and is the focus of this study. Lipoprotein-associated phospholipase A2 (Lp-PLA2) is linked to MAFLD risk. This study investigated the effects of metformin on ferroptosis in free fatty acid (FFA)-treated Huh7 hepatoma cells and its association with MAFLD risk. Using Western blot, immunofluorescence, and ELISA, this study revealed that FFA treatment led to increased intracellular fat and iron accumulation, heightened Lp-PLA2 expression, reduced levels of the cysteine transporter SLC7A11 and glutathione peroxidase 4 (GPX4), altered glutathione (GSH)/oxidized glutathione (GSSG) ratios, generation of reactive oxygen species (ROS), and initiation of lipid peroxidation, which ultimately resulted in cell ferroptosis. Importantly, metformin reversed FFA-induced iron accumulation, and this effect was attenuated by ferrostatin-1 but enhanced by erastin, RSL3, and si-GPX4. Additionally, metformin activated antioxidant and antiapoptotic mechanisms, which reduced lipid peroxidation and suppressed Lp-PLA2 expression in FFA-treated Huh7 cells. In conclusion, our findings indicate that metformin may protect against MAFLD by inhibiting iron accumulation and Lp-PLA2 expression through the ROS, ferroptosis, and apoptosis signaling pathways. This study highlights potential therapeutic strategies for managing MAFLD-related risks and emphasizes the diverse roles of metformin in maintaining hepatocyte balance.

JNK inhibitor and ferroptosis modulator as possible therapeutic modalities in Alzheimer disease (AD)

Alzheimer disease (AD) is among the most prevalent neurodegenerative diseases globally, marked by cognitive and behavioral disruptions. Ferroptosis is a form of controlled cell death characterized by intracellular iron accumulation associated with lipid peroxide formation, which subsequently promotes AD initiation and progression. We hypothesized that targeting the ferroptosis pathway may help in AD management. Therefore, our study aimed to evaluate the potential neuroprotective effect of the antifungal Ciclopirox olamine (CPX-O) that acts through iron chelation. We employed CPX-O separately or in combination with the JNK inhibitor (SP600125) in a mice model of AlCl3-induced AD. Animals underwent examination for behavioral, biochemical, histological, and immunohistochemical findings. Our results revealed that AlCl3 was associated with disruptions in learning and memory parameters, neuronal degeneration in the hippocampus, increased immunoreactivity of amyloid-β and tau proteins, a significant rise in iron, nitric oxide (NO), malondialdehyde (MDA), JNK, and P53 levels, along with the significant decrease in glutathione peroxidase activity. Interestingly, the administration of CPX-O alone or in combination with SP600125 in the AlCl3-induced AD model caused an improvement in the previously described examination findings. Therefore, CPX-O may be a promising candidate for AD treatment, and future clinical trials will be required to confirm these preclinical findings.

Hepatocyte activation and liver injury following cerebral ischemia promote HMGB1-mediated hepcidin upregulation in hepatocytes and regulation of systemic iron levels

We previously reported that high mobility group box 1 (HMGB1), a danger-associated molecular pattern (DAMP), increases intracellular iron levels in the postischemic brain by upregulating hepcidin, a key regulator of iron homeostasis, triggering ferroptosis. Since hepatocytes are the primary cells that produce hepcidin and control systemic iron levels, we investigated whether cerebral ischemia induces hepcidin upregulation in hepatocytes. Following middle cerebral artery occlusion (MCAO) in a rodent model, significant liver injury was observed. This injury was evidenced by significantly elevated Eckhoff’s scores and increased serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Additionally, total iron levels were significantly elevated in the liver, with intracellular iron accumulation detected in hepatocytes. Hepcidin expression in the liver, which is primarily localized in hepatocytes, increased significantly starting at 3 h after MCAO and continued to increase rapidly, reaching a peak at 24 h. Interestingly, HMGB1 levels in the liver were also significantly elevated after MCAO, with the disulfide form of HMGB1 being the major subtype. In vitro experiments using AML12 hepatocytes showed that recombinant disulfide HMGB1 significantly upregulated hepcidin expression in a Toll-like receptor 4 (TLR4)- and RAGE-dependent manner. Furthermore, treatment with a ROS scavenger and a peptide HMGB1 antagonist revealed that both ROS generation and HMGB1 induction contributed to hepatocyte activation and liver damage following MCAO–reperfusion. In conclusion, this study revealed that cerebral ischemia triggers hepatocyte activation and liver injury. HMGB1 potently induces hepcidin not only in the brain but also in the liver, thereby influencing systemic iron homeostasis following ischemic stroke.

Astrocyte-derived lactoferrin inhibits neuronal ferroptosis by reducing iron content and GPX4 degradation in APP/PS1 transgenic mice

Increased astrocytic lactoferrin (Lf) expression was observed in the brains of elderly individuals and Alzheimer's disease (AD) patients. Our previous study revealed that astrocytic Lf overexpression improved cognitive capacity by facilitating Lf secretion to neurons to inhibit β-amyloid protein (Aβ) production in APP/PS1 mice. Here, we further discovered that astrocytic Lf overexpression inhibited neuronal loss by decreasing iron accumulation and increasing glutathione peroxidase 4 (GPX4) expression in neurons within APP/PS1 mice. Furthermore, human Lf (hLf) treatment inhibited ammonium ferric citrate (FAC)-induced ferroptosis by chelating intracellular iron. Additionally, machine learning analysis uncovered a correlation between Lf and GPX4. hLf treatment boosted low-density lipoprotein receptor-related protein 1 (LRP1) internalization and facilitated its interaction with heat shock cognate 70 (HSC70), thereby inhibiting HSC70 binds to GPX4, and eventually attenuating GPX4 degradation and FAC-induced ferroptosis. Overall, astrocytic Lf overexpression inhibited neuronal ferroptosis through two pathways: reducing intracellular iron accumulation and promoting GPX4 expression via inhibiting chaperone-mediated autophagy (CMA)-mediated GPX4 degradation. Hence, upregulating astrocytic Lf expression is a promising strategy for combating AD.

An Overview of Hexavalent Chromium-Induced Necroptosis, Pyroptosis, and Ferroptosis.

Heavy metals are common environmental industrial pollutants. Due to anthropogenic activity, chromium, especially its hexavalent form [Cr(VI)], is a widespread environmental contaminant that poses a threat to human health. In this review paper, we summarize the currently reported molecular mechanisms involved in chromium toxicity with a focus on the induction of pro-inflammatory non-apoptotic cell death pathways such as necroptosis, pyroptosis, and ferroptosis. The review highlights the ability of chromium to induce necroptosis, pyroptosis, and ferroptosis revealing the signaling pathways involved. Cr(VI) can induce RIPK1/RIPK3-dependent necroptosis both in vitro and in vivo. Chromium toxicity is associated with pyroptotic NLRP3 inflammasome/caspase-1/gasdermin D-dependent secretion of IL-1β and IL-18. Furthermore, this review emphasizes the role of redox imbalance and intracellular iron accumulation in Cr(VI)-induced ferroptosis. Of note, the crosstalk between the investigated lethal subroutines in chromium-induced toxicity is primarily mediated by reactive oxygen species (ROS), which are suggested to act as a rheostat determining the cell death pathway in cells exposed to chromium. The current study provides novel insights into the pro-inflammatory effects of chromium, since necroptosis, pyroptosis, and ferroptosis affect inflammation owing to their immunogenic properties linked primarily with damage-associated molecular patterns. Inhibition of these non-apoptotic lethal subroutines can be considered a therapeutic strategy to reduce the toxicity of heavy metals, including chromium.

Rehmanniae Radix Praeparata aqueous extract improves hepatic ischemia/reperfusion injury by restoring intracellular iron homeostasis

Hepatic ischemia/reperfusion injury (HIRI) is a common pathophysiological condition occurring during or after liver resection and transplantation, leading to hepatic viability impairment and functional deterioration. Recently, ferroptosis, a newly recognized form of programmed cell death, has been implicated in IRI. Rehmanniae Radix Praeparata (RRP), extensively used in Chinese herbal medicine for its hepatoprotective, anti-inflammatory, and antioxidant properties, presents a potential therapeutic approach. However, the mechanisms by which RRP mitigates HIRI, particularly through the regulation of ferroptosis, remain unclear. In this study, we developed a HIRI mouse model and monocrotaline (MCT)- and erastin-induced in vitro hepatocyte injury models. We conducted whole-genome transcriptome analysis to elucidate the protective effects and mechanisms of RRP on HIRI. The RRP aqueous extract was characterized by the presence of acteoside, rehmannioside D, and 5-hydroxymethylfurfural. Our results demonstrate that the RRP aqueous extract ameliorated oxidative stress, reduced intracellular iron accumulation, and attenuated HIRI-induced liver damage. Additionally, RRP significantly inhibited hepatocyte death by restoring intracellular iron homeostasis both in vivo and in vitro. Mechanistically, the RRP aqueous extract reduced intrahepatocellular iron accumulation by inhibiting ZIP14-mediated iron uptake, promoting hepcidin- and ferroportin-mediated iron efflux, and ameliorating mitochondrial iron aggregation through upregulation of Cisd1 expression. Moreover, siRNA-mediated inhibition of hamp synergistically enhanced the RRP aqueous extract’s inhibitory effect on ferroptosis. In conclusion, our study elucidates the mechanisms by which RRP aqueous extracts alleviate HIRI, highlighting the restoration of iron metabolic balance. These findings position RRP as a promising candidate for clinical intervention in HIRI treatment.

BNIP3-mediated mitophagy attenuates hypoxic-ischemic brain damage in neonatal rats by inhibiting ferroptosis through P62-KEAP1-NRF2 pathway activation to maintain iron and redox homeostasis.

As a major contributor to neonatal death and neurological sequelae, hypoxic-ischemic encephalopathy (HIE) lacks a viable medication for treatment. Oxidative stress induced by hypoxic-ischemic brain damage (HIBD) predisposes neurons to ferroptosis due to the fact that neonates accumulate high levels of polyunsaturated fatty acids for their brain developmental needs but their antioxidant capacity is immature. Ferroptosis is a form of cell death caused by excessive accumulation of iron-dependent lipid peroxidation and is closely associated with mitochondria. Mitophagy is a type of mitochondrial quality control mechanism that degrades damaged mitochondria and maintains cellular homeostasis. In this study we employed mitophagy agonists and inhibitors to explore the mechanisms by which mitophagy exerted ferroptosis resistance in a neonatal rat HIE model. Seven-days-old neonatal rats were subjected to ligation of the right common carotid artery, followed by exposure to hypoxia for 2 h. The neonatal rats were treated with a mitophagy activator Tat-SPK2 peptide (0.5, 1 mg/kg, i.p.) 1 h before hypoxia, or in combination with mitochondrial division inhibitor-1 (Mdivi-1, 20 mg/kg, i.p.), and ferroptosis inhibitor Ferrostatin-1 (Fer-1) (2 mg/kg, i.p.) at the end of the hypoxia period. The regulation of ferroptosis by mitophagy was also investigated in primary cortical neurons or PC12 cells in vitro subjected to 4 or 6 h of OGD followed by 24 h of reperfusion. We showed that HIBD induced mitochondrial damage, ROS overproduction, intracellular iron accumulation, lipid peroxidation and ferroptosis, which were significantly reduced by the pretreatment with Tat-SPK2 peptide, and aggravated by the treatment with Mdivi-1 or BNIP3 knockdown. Ferroptosis inhibitors Fer-1 and deferoxamine B (DFO) reversed the accumulation of iron and lipid peroxides caused by Mdivi-1, hence reducing ferroptosis triggered by HI. We demonstrated that Tat-SPK2 peptide-activated BNIP3-mediated mitophagy did not alleviate neuronal ferroptosis through the GPX4-GSH pathway. BNIP3-mediated mitophagy drove the P62-KEAP1-NRF2 pathway, which conferred ferroptosis resistance by maintaining iron and redox homeostasis via the regulation of FTH1, HO-1, and DHODH/FSP1-CoQ10-NADH. This study may provide a new perspective and a therapeutic drug for the treatment of neonatal HIE.

Identification of Isoliensinine as a Ferroptosis Suppressor with Iron-Chelating Activity.

Ferroptosis is a type of regulated cell death driven by the iron-dependent accumulation of lipid peroxides. The high involvement of ferroptosis in diverse human diseases highlights the need for the identification of new chemotypes with anti-ferroptotic activity. Here, we performed a natural product library screening in HT1080 fibrosarcoma cells and identified licochalcone A (LA), isoeugenyl acetate (ISA), and isoliensinine (ISL) as suppressors of either RSL3- or IKE-induced ferroptosis. Mechanistically, ferroptosis resistance conferred by these compounds is mainly through GPX4/NRF2-independent mechanisms. Among them, only ISL could effectively rescue ferroptosis induced by FINO2, which is a stable oxidant of ferrous iron, suggesting that ISL may have the properties of an iron chelator. Consistent with the hypothesis, both computational tools and X-ray photoelectron spectroscopy supported the binding between ISL and iron ions. And ISL greatly inhibited excessive iron-dependent ferroptotic cell death through limiting intracellular iron accumulation. Furthermore, its iron chelator activity also protected mice from organ injury in an acute iron overload model. In conclusion, this study provided valuable insights for developing effective anti-ferroptosis agents from natural products, which represent a potential therapeutic strategy for treating ferroptosis-associated organ damage.

The intracellular accumulation of iron coincides with enhanced biohydrogen production by Thermoanaerobacterium thermosaccharolyticum

The aim of this study was to investigate the effects of different doses (10–200 mg/L) of magnetite (FeO·Fe2O3), Fe0, Ni0, and FeCl3 on the efficiency of dark fermentative H2 production from cheese whey using Thermoanaerobacterium thermosaccharolyticum SP-H2. Energy conversion efficiency and hydrogen yield increased significantly by 22.7 % and 34.8 %, respectively, when 10 mg/L of magnetite was added, and hydrogenase activity increased by 23.6 % when 100 mg/L of Fe0 was added compared to the control (p < 0.001). Using scanning electron microscopy and energy dispersive X-ray spectroscopy, it was found that during the early exponential phase of hydrogen evolution, T. thermosaccharolyticum cells accumulated up to 11.2 times more Fe (up to 2.8 wt%) in the presence of optimal concentrations of Fe additives compared to the control. Intracellular iron accumulation and hydrogen yield were positively correlated with acetate concentration (p < 0.001), suggesting an efficient acetate pathway for dark fermentation. During the stationary growth phase, with almost no H2 production, the intracellular iron content decreased by up to 67.9 %. The phenomenon of changes in the amount of metal in cells, depending on the phase of hydrogen production, was demonstrated for the first time. The findings suggest that intracellular metals can be used in cell metabolism to produce H2, and the mechanisms behind this process need further investigation. Overall, this study provides valuable insights into the optimal forms and doses of metals for enhancing biohydrogen production, as well as possible research directions for the potential use of metals by microorganisms during additive-assisted dark fermentation of carbohydrate-rich wastes.

Hypoxia-inducible factor-1α can reverse the Adriamycin resistance of breast cancer adjuvant chemotherapy by upregulating transferrin receptor and activating ferroptosis.

Breast cancer is a common malignant tumor in women. Ferroptosis, a programmed cell death pathway, is closely associated with breast cancer and its resistance. The transferrin receptor (TFRC) is a key factor in ferroptosis, playing a crucial role in intracellular iron accumulation and the occurrence of ferroptosis. This study investigates the influence and significance of TFRC and its upstream transcription factor hypoxia-inducible factor-1α (HIF1α) on the efficacy of neoadjuvant therapy in breast cancer. The differential gene obtained from clinical samples through genetic sequencing is TFRC. Bioinformatics analysis revealed that TFRC expression in breast cancer was significantly greater in breast cancer tissues than in normal tissues, but significantly downregulated in Adriamycin (ADR)-resistant tissues. Iron-responsive element-binding protein 2 (IREB2) interacts with TFRC and participates in ferroptosis. HIF1α, an upstream transcription factor, positively regulates TFRC. Experimental results indicated higher levels of ferroptosis markers in breast cancer tissue than in normal tissue. In the TAC neoadjuvant regimen-sensitive group, iron ion (Fe2+) and malondialdehyde (MDA) levels were greater than those in the resistant group (all p < .05). Expression levels of TFRC, IREB2, FTH1, and HIF1α were higher in breast cancer tissue compared to normal tissue. Additionally, the expression of the TFRC protein in the TAC neoadjuvant regimen-sensitive group was significantly higher than that in the resistant group (all p < .05), while the difference in the level of expression of IREB2 and FTH1 between the sensitive and resistant groups was not significant (p > .05). The dual-luciferase assay revealed that HIF1α acts as an upstream transcription factor of TFRC (p < .05). Overexpression of HIF1α in ADR-resistant breast cancer cells increased TFRC, Fe2+, and MDA content. After ADR treatment, the cell survival rate decreased significantly, and ferroptosis could be reversed by the combined application of Fer-1 (all p < .05). In conclusion, ferroptosis and chemotherapy resistance are correlated in breast cancer. TFRC is a key regulatory factor influenced by HIF1α and is associated with chemotherapy resistance. Upregulating HIF1α in resistant cells may reverse resistance by activating ferroptosis through TFRC overexpression.

Bromodomain-containing protein 4 knockdown promotes neuronal ferroptosis in a mouse model of subarachnoid hemorrhage.

Neuronal cell death is a common outcome of multiple pathophysiological processes and a key factor in neurological dysfunction after subarachnoid hemorrhage. Neuronal ferroptosis in particular plays an important role in early brain injury. Bromodomain-containing protein 4, a member of the bromo and extraterminal domain family of proteins, participated in multiple cell death pathways, but the mechanisms by which it regulates ferroptosis remain unclear. The primary aim of this study was to investigate how bromodomain-containing protein 4 affects neuronal ferroptosis following subarachnoid hemorrhage in vivo and in vitro. Our findings revealed that endogenous bromodomain-containing protein 4 co-localized with neurons, and its expression was decreased 48 hours after subarachnoid hemorrhage of the cerebral cortex in vivo. In addition, ferroptosis-related pathways were activated in vivo and in vitro after subarachnoid hemorrhage. Targeted inhibition of bromodomain-containing protein 4 in neurons increased lipid peroxidation and intracellular ferrous iron accumulation via ferritinophagy and ultimately led to neuronal ferroptosis. Using cleavage under targets and tagmentation analysis, we found that bromodomain-containing protein 4 enrichment in the Raf-1 promoter region decreased following oxyhemoglobin stimulation in vitro. Furthermore, treating bromodomain-containing protein 4-knockdown HT-22 cell lines with GW5074, a Raf-1 inhibitor, exacerbated neuronal ferroptosis by suppressing the Raf-1/ERK1/2 signaling pathway. Moreover, targeted inhibition of neuronal bromodomain-containing protein 4 exacerbated early and long-term neurological function deficits after subarachnoid hemorrhage. Our findings suggest that bromodomain-containing protein 4 may have neuroprotective effects after subarachnoid hemorrhage, and that inhibiting ferroptosis could help treat subarachnoid hemorrhage.

Daphnetin induces ferroptosis in ovarian cancer by inhibiting NAD(P)H:Quinone oxidoreductase 1 (NQO1)

Ferroptosis, an emerging nonapoptotic, modulated cell death process characterized by iron accumulation and subsequent lipid peroxidation, has been intimately implicated in the development and progression of ovarian cancer (OC). Daphnetin (Daph), a natural product isolated from Daphne Korean Nakai, exhibits anticancer efficacy against various solid tumors. However, the specific role and potential mechanism underlying Daph-mediated modulation of ferroptosis in OC cells remain elusive. This study aims to analyze the proferroptotic impacts of Daph on OC cells and to further explore the underlying mechanisms involved. We used CCK-8, wound healing and Transwell assays to assess whether Daph can inhibit the proliferation and migration of OC cells. Additionally, transmission electron microscopy (TEM), iron measurement, reactive oxygen species (ROS) analysis, lipid peroxidation assays, qRT-PCR and western blotting were utilized to evaluate the impact of Daph on ferroptosis and elucidate the potential underlying mechanism. Furthermore, RNA sequencing analysis, molecular docking analysis, cellular thermal shift assays (CETSAs) and NQO1 activity assays were used to predict and validate the binding and mechanistic interactions between Daph and NQO1. Subcutaneous tumorigenesis models were utilized to examine the effectiveness of Daph (and/or cisplatin) in vivo. Daph exerted antitumor effects by inducing the death and suppressing the migration of A2780 and SKOV3 cells. Further, Daph induced ferroptosis in OC cells, as evidenced by the accumulation of intracellular ferrous iron (Fe2+), ROS and lipid peroxides, as well as the decreases in the glutathione/oxidized glutathione disulfide (GSH/GSSG) ratio and the expression of ferroptosis indicators (SLC7A11 and GPX4). RNA sequencing and molecular docking analyses revealed that the direct interaction between NQO1 and Daph reduced both the activity and expression of NQO1. Importantly, NQO1 overexpression effectively alleviated the effects of Daph on proliferation, migration, and ferroptosis in vitro and in vivo. Interestingly, we also found that combination treatment with Daph, a negative regulator of NQO1, and cisplatin synergistically induced cytotoxicity in OC cells. Our findings are the firstly demonstrated that Daph acts as a novel ferroptosis inducer in OC cells by specifically targeting NQO1 and is thus a promising candidate agent for OC treatment.

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.