Regulation of xanthine oxidoreductase by intracellular iron

2002 ◽  
Vol 283 (6) ◽  
pp. C1722-C1728 ◽  
Author(s):  
Eeva Martelin ◽  
Risto Lapatto ◽  
Kari O. Raivio
Keyword(s):  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Iron Chelation ◽  
Mouse Fibroblast ◽  
Ammonium Citrate ◽  
Ferric Ammonium Citrate ◽  
Mrna Levels ◽  
Xanthine Oxidoreductase ◽  
Intracellular Iron ◽  
Human Embryonic Kidney Cells

Xanthine oxidoreductase (XOR) may produce reactive oxygen species and play a role in ischemia-reperfusion injury. Because tissue iron levels increase after ischemia, and because XOR contains functionally critical iron-sulfur clusters, we studied the effects of intracellular iron on XOR expression. Ferric ammonium citrate and FeSO4elevated intracellular iron levels and increased XOR activity up to twofold in mouse fibroblast and human bronchial epithelial cells. Iron increased XOR protein and mRNA levels, whereas protein and RNA synthesis inhibitors abolished the induction of XOR activity. A human XOR promoter construct (nucleotides +42 to −1937) was not induced by iron in human embryonic kidney cells. Hydroxyl radical scavengers did not block induction of XOR activity by iron. Iron chelation by deferoxamine (DFO) decreased XOR activity but did not lower endogenous XOR protein or mRNA levels. Furthermore, DFO reduced the activity of overexpressed human XOR but not the amount of immunoreactive protein. Our data show that XOR activity is transcriptionally induced by iron but posttranslationally inactivated by iron chelation.

scholarly journals ATF3 contributes to brucine-triggered glioma cell ferroptosis via promotion of hydrogen peroxide and iron

2021 ◽  
Author(s):  
Shan Lu ◽  
Xuan-zhong Wang ◽  
Chuan He ◽  
Lei Wang ◽  
Shi-peng Liang ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Cell Death ◽  
Er Stress ◽  
Glioma Cell ◽  
Nuclear Translocation ◽  
Indole Alkaloid ◽  
Ammonium Citrate ◽  
Ferric Ammonium Citrate ◽  
Activating Transcription Factor 3 ◽  
Intracellular Iron

AbstractFerroptotic cell death is characterized by iron-dependent lipid peroxidation that is initiated by ferrous iron and H2O2 via Fenton reaction, in which the role of activating transcription factor 3 (ATF3) remains elusive. Brucine is a weak alkaline indole alkaloid extracted from the seeds of Strychnos nux-vomica, which has shown potent antitumor activity against various tumors, including glioma. In this study, we showed that brucine inhibited glioma cell growth in vitro and in vivo, which was paralleled by nuclear translocation of ATF3, lipid peroxidation, and increases of iron and H2O2. Furthermore, brucine-induced lipid peroxidation was inhibited or exacerbated when intracellular iron was chelated by deferoxamine (500 μM) or improved by ferric ammonium citrate (500 μM). Suppression of lipid peroxidation with lipophilic antioxidants ferrostatin-1 (50 μM) or liproxstatin-1 (30 μM) rescued brucine-induced glioma cell death. Moreover, knockdown of ATF3 prevented brucine-induced accumulation of iron and H2O2 and glioma cell death. We revealed that brucine induced ATF3 upregulation and translocation into nuclei via activation of ER stress. ATF3 promoted brucine-induced H2O2 accumulation via upregulating NOX4 and SOD1 to generate H2O2 on one hand, and downregulating catalase and xCT to prevent H2O2 degradation on the other hand. H2O2 then contributed to brucine-triggered iron increase and transferrin receptor upregulation, as well as lipid peroxidation. This was further verified by treating glioma cells with exogenous H2O2 alone. Moreover, H2O2 reversely exacerbated brucine-induced ER stress. Taken together, ATF3 contributes to brucine-induced glioma cell ferroptosis via increasing H2O2 and iron.

Abstract 782: Fra2 Mediates Oxygen-induced TGFbeta-1 mRNA Expression In Adult Cardiac Fibroblasts: Significance In Myocardial Fibrosis Following Ischemia-reperfusion Injury

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Sashwati Roy ◽  
Savita Khanna ◽  
Chandan K Sen
Keyword(s):  
Mrna Expression ◽  
Transforming Growth Factor Beta ◽  
Cardiac Fibrosis ◽  
Transforming Growth Factor ◽  
Ischemia Reperfusion Injury ◽  
Cardiac Fibroblasts ◽  
Ischemia Reperfusion ◽  
Luciferase Reporter ◽  
Mrna Levels

Background . Transforming growth factor beta-1 (TGFbeta-1) is a key cytokine implicated in the development of cardiac fibrosis following ischemia-reperfusion (IR) injury. The profibrotic effects of TGFbeta-1 are primarily attributable to the differentiation of cardiac fibroblasts (CF) to myofibroblasts. Previously, we have reported perceived hyperoxia (Circ Res 92:264 –71), sub-lethal reoxygenation shock during IR, induces differentiation of CF to myofibroblasts at the infarct site. The mechanisms underlying oxygen-sensitive induction of TGFbeta-1 mRNA remain to be characterized. Hypothesis . Fra2 mediates oxygen-induced TGFbeta-1 mRNA expression in adult cardiac fibroblasts. Methods. TGFbeta-1 mRNA expression in infarct tissue was investigated in an IR injury model. The left anterior descending coronary artery of mice was transiently occluded for 60 minutes followed by reperfusion to induce IR injury. Spatially resolved infarct and non-infarct tissues were collected at 0, 1, 3, 5, and 7 days post-IR using laser capture microdissection. TGFbeta-1 mRNA levels were measured using real-time PCR. To investigate the role of oxygen in the regulation of TGFbeta-1, we used our previously reported model of perceived hyperoxia where CF (from 5wks old mice) after isolation were cultured at 5%O 2 (physiological pO 2 ) followed by transferring them to 20%O 2 to induce hyperoxic insult. Results & Conclusions. In vivo, a significant increase (p<0.01; n=5) in TGFbeta-1 mRNA was observed at the infarct site already at day 1 post-IR. The levels continued to increase until day 7 post-IR. In vitro, exposure of CF to 20%O 2 hyperoxic insult induced TGFbeta-1 mRNA (p<0.001; n=4) and protein (p<0.01; n=4) expression. Using a TGFbeta-1 promoter-luciferase reporter and DNA binding assays, we collected first evidence that AP-1 and its component Fra2 as major mediators of oxygen-induced TGFbeta-1 expression. Exposure to 20%O 2 resulted in increased localization of Fra2 in nucleus. siRNA-dependent Fra-2 knock-down completely abrogated oxygen-induced TGFbeta1 expression. In conclusion, this study presents first evidence that Fra-2 is involved in inducible TGFbeta1 expression in CF. Fra2 was noted as being central in regulating oxygen-induced TGFbeta-1 expression.s

Expression of SSAT, a novel biomarker of tubular cell damage, increases in kidney ischemia-reperfusion injury

2003 ◽  
Vol 284 (5) ◽  
pp. F1046-F1055 ◽  
Author(s):  
Kamyar Zahedi ◽  
Zhaohui Wang ◽  
Sharon Barone ◽  
Anne E. Prada ◽  
Caitlin N. Kelly ◽  
...  
Keyword(s):  
Renal Failure ◽  
Acute Renal Failure ◽  
Reperfusion Injury ◽  
Cell Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Atp Depletion ◽  
Tubular Cell ◽  
Mrna Levels ◽  
Tubular Injury

Ischemia-reperfusion injury (IRI) is the major cause of acute renal failure in native and allograft kidneys. Identifying the molecules and pathways involved in the pathophysiology of renal IRI will yield valuable new diagnostic and therapeutic information. To identify differentially regulated genes in renal IRI, RNA from rat kidneys subjected to an established renal IRI protocol (bilateral occlusion of renal pedicles for 30 min followed by reperfusion) and time-matched kidneys from sham-operated animals was subjected to suppression subtractive hybridization. The level of spermidine/spermine N 1-acetyltransferase (SSAT) mRNA, an essential enzyme for the catabolism of polyamines, increased in renal IRI. SSAT expression was found throughout normal kidney tubules, as detected by nephron segment RT-PCR. Northern blots demonstrated that the mRNA levels of SSAT are increased by greater than threefold in the renal cortex and by fivefold in the renal medulla at 12 h and returned to baseline at 48 h after ischemia. The increase in SSAT mRNA was paralleled by an increase in SSAT protein levels as determined by Western blot analysis. The concentration of putrescine in the kidney increased by ∼4- and ∼7.5-fold at 12 and 24 h of reperfusion, respectively, consistent with increased functional activity of SSAT. To assess the specificity of SSAT for tubular injury, a model of acute renal failure from Na+depletion (without tubular injury) was studied; SSAT mRNA levels remained unchanged in rats subjected to Na+ depletion. To distinguish SSAT increases from the effects of tubular injury vs. uremic toxins, SSAT was increased in cis-platinum-treated animals before the onset of renal failure. The expression of SSAT mRNA and protein increased by ∼3.5- and >10-fold, respectively, in renal tubule epithelial cells subjected to ATP depletion and metabolic poisoning (an in vitro model of kidney IRI). Our results suggest that SSAT is likely a new marker of tubular cell injury that distinguishes acute prerenal from intrarenal failure.

LncRNA PVT1 Mediated by ZFP36L2 Regulates Myocardial Ischemia/Reperfusion Injury and Attenuates Mitochondrial Fusion and Fission via Activating miR-21-5p/MARCH5 Axis

2020 ◽  
Author(s):  
Weifeng Huang ◽  
Qin Tan ◽  
Yong Guo ◽  
Yongmei Cao ◽  
Jiawei Shang ◽  
...  
Keyword(s):  
Zinc Finger Protein ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Mitochondrial Fission ◽  
Tumor Biology ◽  
Luciferase Reporter ◽  
Mitochondrial Morphology ◽  
Mrna Levels

Abstract BackgroundAmong several leading cardiovascular disorders, ischemia-reperfusion (I/R) injury causes severe manifestations including acute heart failure, inflammation, and systemic dysfunction. Recently, there has been increasing evidence suggesting that alterations in mitochondrial morphology play a role in the prognoses of cardiac disorders. Long non-coding RNAs (lncRNAs) form major regulatory networks to modify gene transcription and translation. While several roles of lncRNAs have been explored in cancer and tumor biology, their implications on mitochondrial morphology and functions remain to be elucidated. MethodsThe functional roles of ZFP36L2 and lncRNA PVT1 were determined by a series of cardiomyocyte hypoxia/ reoxygenation (H/R) in vitro and myocardial I/R injury in vivo experiments. Quantitative Reverse transcription-polymerase chain reaction (qRT-PCR) and western blot analysis were used to detect the mRNA levels of ZFP36L2 and mitochondrial fission and fusion markers in the myocardial tissues and cardiomyocyte. Cardiac function was determined by immunohistochemistry, H&E, Masson’s staining and echocardiogram. Ultrastructural analysis of mitochondrial fission was performed using transmission electron microscopy (TEM). The mechanistic model of PVT1 with ZFP36L2 and miR-21-5p with MARCH5 was detected by subcellular fraction, RNA pull down, FISH, and luciferase reporter assays.ResultsIn this study, we report a novel regulatory axis involving lncRNA PVT1, microRNA miR-21-5p, and E3 ubiquitin ligase MARCH5, which alters mitochondrial morphology during myocardial I/R injury. Using an in vivo I/R injury mouse model and in vitro cardiomyocyte H/R model, we observed that zinc finger protein ZFP36L2 directly associated with PVT1 and altered mitochondrial fission and fusion. PVT1 also interacted with miR-21-5p and suppressed its expression and activity. Furthermore, we identified MARCH5 as a modifier of miR-21-5p, and expression of MARCH5 and its effect on mitochondrial fission and fusion were directly proportional to PVT1 expression during H/R injury. ConclusionsOur findings demonstrated that manipulation of PVT1-miR-21-5p-MARCH5-mediated mitochondrial fission and fusion via ZFP36L2 may be a novel therapeutic approach to regulate myocardial I/R injury.

scholarly journals Preconditioning reduces tissue complement gene expression in the rabbit isolated heart

1999 ◽  
Vol 277 (6) ◽  
pp. H2373-H2380 ◽  
Author(s):  
Elaine J. Tanhehco ◽  
Koji Yasojima ◽  
Patrick L. McGeer ◽  
Ruth A. Washington ◽  
Kenneth S. Kilgore ◽  
...  
Keyword(s):  
Ischemia Reperfusion Injury ◽  
Isolated Heart ◽  
Ischemia Reperfusion ◽  
Membrane Attack Complex ◽  
Global Ischemia ◽  
Mrna Levels ◽  
Similar Reduction ◽  
Complement Components ◽  
Complex Protein ◽  
Myocardial Ischemia Reperfusion

Both preconditioning and inhibition of complement activation have been shown to ameliorate myocardial ischemia-reperfusion injury. The recent demonstration that myocardial tissue expresses complement components led us to investigate whether preconditioning affects complement expression in the isolated heart. Hearts from New Zealand White rabbits were exposed to either two rounds of 5 min global ischemia followed by 10 min reperfusion (ischemic preconditioning) or 10 μM of the ATP-dependent K+(KATP) channel opener pinacidil for 30 min (chemical preconditioning) before induction of 30 min global ischemia followed by 60 min of reperfusion. Both ischemic and chemical preconditioning significantly ( P < 0.05) reduced myocardial C1q, C1r, C3, C8, and C9 mRNA levels. Western blot and immunohistochemistry demonstrated a similar reduction in C3 and membrane attack complex protein expression. The KATPchannel blocker glyburide (10 μM) reversed the depression of C1q, C1r, C3, C8, and C9 mRNA expression observed in the pinacidil-treated hearts. The results suggest that reduction of local tissue complement production may be one means by which preconditioning protects the ischemic myocardium.

scholarly journals Fibrinogen β–derived Bβ15-42 peptide protects against kidney ischemia/ reperfusion injury

Blood ◽  
2011 ◽  
Vol 118 (7) ◽  
pp. 1934-1942 ◽  
Author(s):  
Aparna Krishnamoorthy ◽  
Amrendra Kumar Ajay ◽  
Dana Hoffmann ◽  
Tae-Min Kim ◽  
Victoria Ramirez ◽  
...  
Keyword(s):  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
High Sensitivity ◽  
Kidney Damage ◽  
Therapeutic Interventions ◽  
Mrna Levels ◽  
Renal Tubular Cells ◽  
Renal Tubular ◽  
Injury And Repair

AbstractIschemia/reperfusion (I/R) injury in the kidney is a major cause of acute kidney injury (AKI) in humans and is associated with significantly high mortality. To identify genes that modulate kidney injury and repair, we conducted genome-wide expression analysis in the rat kidneys after I/R and found that the mRNA levels of fibrinogen (Fg)α, Fgβ, and Fgγ chains significantly increase in the kidney and remain elevated throughout the regeneration process. Cellular characterization of Fgα and Fgγ chain immunoreactive proteins shows a predominant expression in renal tubular cells and the localization of immunoreactive Fgβ chain protein is primarily in the renal interstitium in healthy and regenerating kidney. We also show that urinary excretion of Fg is massively increased after kidney damage and is capable of distinguishing human patients with acute or chronic kidney injury (n = 25) from healthy volunteers (n = 25) with high sensitivity and specificity (area under the receiver operating characteristic of 0.98). Furthermore, we demonstrate that Fgβ-derived Bβ15-42 peptide administration protects mice from I/R-induced kidney injury by aiding in epithelial cell proliferation and tissue repair. Given that kidney regeneration is a major determinant of outcome for patients with kidney damage, these results provide new opportunities for the use of Fg in diagnosis, prevention, and therapeutic interventions in kidney disease.

scholarly journals Endothelial STAT3 Modulates Protective Mechanisms in a Mouse Ischemia-Reperfusion Model of Acute Kidney Injury

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Shataakshi Dube ◽  
Tejasvi Matam ◽  
Jessica Yen ◽  
Henry E. Mang ◽  
Pierre C. Dagher ◽  
...  
Keyword(s):  
Acute Kidney Injury ◽  
Ischemia Reperfusion Injury ◽  
Leukocyte Adhesion ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Organ Injury ◽  
Mrna Levels ◽  
Kidney Dysfunction ◽  
Stat3 Signaling ◽  
Proximal Tubular

STAT3 is a transcriptional regulator that plays an important role in coordinating inflammation and immunity. In addition, there is a growing appreciation of the role STAT3 signaling plays in response to organ injury following diverse insults. Acute kidney injury (AKI) from ischemia-reperfusion injury is a common clinical entity with devastating consequences, and the recognition that endothelial alterations contribute to kidney dysfunction in this setting is of growing interest. Consequently, we used a mouse with a genetic deletion of Stat3 restricted to the endothelium to examine the role of STAT3 signaling in the pathophysiology of ischemic AKI. In a mouse model of ischemic AKI, the loss of endothelial STAT3 signaling significantly exacerbated kidney dysfunction, morphologic injury, and proximal tubular oxidative stress. The increased severity of ischemic AKI was associated with more robust endothelial-leukocyte adhesion and increased tissue accumulation of F4/80+ macrophages. Moreover, important proximal tubular adaptive mechanisms to injury were diminished in association with decreased tissue mRNA levels of the epithelial cell survival cytokine IL-22. In aggregate, these findings suggest that the endothelial STAT3 signaling plays an important role in limiting kidney dysfunction in ischemic AKI and that selective pharmacologic activation of endothelial STAT3 signaling could serve as a potential therapeutic target.

Silencing of sodium/hydrogen exchanger in the heart by direct injection of naked siRNA

2011 ◽  
Vol 111 (2) ◽  
pp. 566-572 ◽  
Author(s):  
Patricio E. Morgan ◽  
María V. Correa ◽  
Irene L. Ennis ◽  
Ariel A. Diez ◽  
Néstor G. Pérez ◽  
...  
Keyword(s):  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Direct Injection ◽  
Experimental Models ◽  
Left Ventricular ◽  
Maximal Velocity ◽  
Mrna Levels ◽  
Small Interference Rna

Cardiac Na+/H+ exchanger (NHE1) hyperactivity is a central factor in cardiac remodeling following hypertension, myocardial infarction, ischemia-reperfusion injury, and heart failure. Treatment of these pathologies by inhibiting NHE1 is challenging because specific drugs that have been beneficial in experimental models were associated with undesired side effects in clinical practice. In the present work, small interference RNA (siRNA) produced in vitro to specifically silence NHE1 (siRNANHE1) was injected once in vivo into the apex of the left ventricular wall of mouse myocardium. After 48 h, left ventricular NHE1 protein expression was reduced in siRNANHE1-injected mice compared with scrambled siRNA by 33.2 ± 3.4% ( n = 5; P < 0.05). Similarly, NHE1 mRNA levels were reduced by 20 ± 2.0% ( n = 4). At 72 h, siRNANHE1 spreading was evident from the decrease in NHE1 expression in three portions of the myocardium (apex, medium, base). NHE1 function was assessed based on maximal velocity of intracellular pH (pHi) recovery (dpHi/d t) after an ammonium prepulse-induced acidic load. Maximal dpHi/d t was reduced to 14% in siRNANHE1-isolated left ventricular papillary muscles compared with scrambled siRNA. In conclusion, only one injection of naked siRNANHE1 successfully reduced NHE1 expression and activity in the left ventricle. As has been previously suggested, extensive NHE1 expression reduction may indicate myocardial spread of siRNA molecules from the injection site through gap junctions, providing a valid technique not only for further research into NHE1 function, but also for consideration as a potential therapeutic strategy.

Synergistic Up-Regulation of Heme Oxygenase-1 in Human Liver by Heme and siRNA to Bach1:Possible Therapeutic Implications.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1633-1633
Author(s):  
Tahereh Ghaziani ◽  
Ying Shan ◽  
Richard W. Lambrecht ◽  
Herbert L. Bonkovsky
Keyword(s):  
Gene Expression ◽  
Heme Oxygenase ◽  
Ischemia Reperfusion Injury ◽  
Tissue Injury ◽  
Ischemia Reperfusion ◽  
Negative Regulator ◽  
Heme Oxygenase 1 ◽  
Significant Finding ◽  
Mrna Levels ◽  
Protein Levels

Abstract Background: Heme oxygenase-1 (HO-1) is an antioxidant defense enzyme that converts toxic heme into antioxidants. HO-1 is strongly up-regulated by its physiologic substrate, heme, which is currently the treatment of choice for acute attacks of porphyria and which may have other therapeutic uses, as well (e.g., for cytoprotection or amelioration of ischemia/reperfusion injury by increasing supply of carbon monoxide, biliverdin, or bilirubin). Up-regulation of HO-1 expression has been associated with increased resistance to tissue injury. Bach1 is a bZip protein which forms heterodimers with small Maf proteins. HO-1 is expressed at higher levels in tissues of Bach1-deficient mice, indicating that Bach1 acts as a negative regulator of the mouse HO-1 gene. The molecular mechanism that confers repression of HO-1 by Bach1, and whether there are similar effects in human cells, has remained elusive. The aim of this study was to assess whether modulation of human hepatic Bach1 expression by siRNA technology influences HO-1 gene expression and whether such gene silencing would enhance the inducing effects of heme on HO-1. Methods: siRNAs targeted 4 different positions of human Bach1 mRNA were designed and synthesized. We transfected Bach1-siRNA (25–200 nM) into Huh-7 cells using Lipofectamine for 24–72 h, after which, cells were treated with or without heme. We quantified HO-1 and Bach1 mRNA and protein levels by quantitative RT-PCR and western blotting, respectively. Effects and specificity of Bach1-siRNA were analyzed and compared with those of non-Bach1 related siRNAs (non-specific control-duplex (NSCD) and LaminB2-siRNA). Results: Bach1-siRNAs (25–200 nM) transfected into Huh-7 cells for 24–72 h significantly reduced Bach1 mRNA and protein levels approximately 80%, compared with non siRNA treated cells. In contrast, transfection with same amounts of NSCD or LaminB2 siRNA did not reduce Bach1 mRNA or protein levels, confirming the specificity of Bach1-siRNA in Huh-7 cells. A significant finding of these studies was the 7-fold up-regulation of the HO-1 gene in Bach1-siRNA transfected cells, compared to cells without Bach1-siRNA or those transfected with NSCD or LaminB2. Bach1, NSCD, and LaminB2 siRNAs had no effect on HO-2 or 5-aminolevulinate synthase-1 mRNA levels (two genes that are not induced by heme). The effects of increasing concentrations of heme (up to 10 μM) in the presence or absence of Bach1-siRNA on the levels of HO-1 mRNA expression are shown in the Figure. For all of the heme concentrations tested, the levels of HO-1 mRNA were greater when Bach1 siRNA was present. Conclusions: Bach1 has a specific and selective effect to repress expression of human hepatic HO-1. Silencing of the Bach1 gene by siRNAs may be a useful method for up-regulating HO-1 gene expression. The combination of intravenous heme and Bach1 silencing may be useful for therapy of acute porphyrias in relapse or other conditions in which up-regulation of HO-1 may be beneficial. (Supported by grants from NIH [DK38825] and Ovation Pharmaceuticals, Inc.) Figure Figure

scholarly journals NCOA4-Mediated Ferritinophagy Is Essential for HT22 Neuronal Cell Survival During Iron Deficiency (OR15-07-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Emily Bengson ◽  
Moon-Suhn Ryu
Keyword(s):  
Cell Death ◽  
Iron Deficiency ◽  
Iron Overload ◽  
Cell Survival ◽  
Neuronal Cell ◽  
Ammonium Citrate ◽  
Ferric Ammonium Citrate ◽  
Mrna Levels ◽  
Ht22 Cells ◽  
Cellular Iron

Abstract Objectives Iron is essential for proper cell function and development. However, mishandled iron may lead to ferroptotic cell death. NCOA4 manages the cellular labile iron pool by controlling the release of ferritin iron via ferritinophagy. The present studies examined the capacity of hippocampal cells in handling iron fluctuation, with particular focus on NCOA4 and ferritin. Methods HT22 mouse hippocampal cells were treated with ferric ammonium citrate (FAC) and deferoxamine (Dfo) to produce cellular iron overload and deprivation, respectively. Ferroptosis was determined by measures of ferrostatin-1 effects and Ptgs2 mRNA. For ferritinophagy studies, Ncoa4 was silenced by siRNA transfections. Functional impacts of impaired ferritinophagy were assessed via CCK-8 cell viability assays and western and qPCR analyses of iron-related genes. Results HT22 cells were highly susceptible to cellular iron overload. FAC-treated cells featured acute morphological changes, decreased viability, and elevated Ptgs2 mRNA abundance. Iron effects were prevented by ferrostatin-1, indicating ferroptosis by cellular iron overload. Dfo alone had minimal impact on cell morphology and viability. NCOA4 protein, but not mRNA, levels were acutely upregulated by Dfo treatments. Ferritin turnover by iron deficiency was impaired in NCOA4-depleted cells, presumably due to impaired ferritinophagy. Moreover, HT22 cells became sensitive to iron deficiency by loss of NCOA4. Conclusions Our studies demonstrate iron can induce ferroptosis in neuronal cells. We also identify NCOA4-mediated ferritinophagy as an integral process for neuronal cell survival during iron deficiency. Further investigation using multi-omics approaches are in progress to determine the mechanisms by which NCOA4 depletion leads to cell death when extracellular iron supply is limited. Funding Sources Supported by the NIFA, USDA, Hatch project under MIN-18–118 and intramural support to M-S.R.

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