Regulation Of Ferritin Research Articles

Ferritin: Significance in viral infections.

As an indispensable trace element, iron is essential for many biological processes. Increasing evidence has shown that virus infection can perturb iron metabolism and play a role in the occurrence and development of viral infection-related diseases. Ferritin plays a crucial role in maintaining the body's iron homoeostasis. It is an important protein to stabilise the iron balance in cells. Ferritin is a 24-mer hollow iron storage protein composed of two subunits: ferritin heavy chain and ferritin light chain. It was reported that ferritin is not only an intra-cellular iron storage protein, but also a pathogenic mediator that enhances the inflammatory process and stimulates the further inflammatory pathway, which is a key member of the vicious pathogenic cycle to perpetuate. Ferritin exerts immuno-suppressive and pro-inflammatory functions during viral infection. In this review, we describe in detail the basic information of ferritin in the first section, including its structural features, the regulation of ferritin. In the second part, we focus on the role of ferritin in viral infection-related diseases and the molecular mechanisms by which viral infection regulates ferritin. The last section briefly outlines the potential of ferritin in antiviral therapy. Given the importance of iron and viral infection, understanding the role of ferritin during viral infection helps us understand the relationship between iron metabolic dysfunction and viral infection, which provides a new direction for the development of antiviral therapeutic drugs.

Clinical significance of serum levels of ferritin, interleukins 6 and 17A in rheumatoid arthritis

Rheumatoid arthritis (RA) is characterized by significant clinical polymorphism. To optimize the treatment of RA, it is necessary to develop a personalized approach based on the determination of the value of various biomarkers in the clinical course of RA. The aim of this work was to determine the levels of proinflammatory cytokines and ferritin in RA and to establish their effect on the clinical course of RA. Methods. The object of the study was 62 patients with RA and 33 healthy volunteers. Serum levels of interleukin 6 (IL-6), interleukin 17A (IL-17A), and ferritin were determined. The study of the interrelationships of the studied indicators with clinical and laboratory-instrumental parameters was carried out. Results. The study found an increase in the levels of cytokines IL-6 and IL-17A, as well as ferritin in RA compared with the control group (p<0.05). Subsequently, all patients were divided into three groups depending on the level of ferritin established in the study. The presence of differences in the main clinical and immunological parameters between the groups was analyzed. Differences in CRP levels were found between the study groups, it was the lowest in the low ferritin group compared to the other two groups (p<0.05). The levels of IL-17A and IL-6 did not differ between the groups (p>0.05). Conclusions. Serum ferritin is a promising and affordable biomarker in RA and can be used for personalized assessment of the condition of a patient with RA, differential diagnosis of anemia, and risk assessment of macrophage activation syndrome. The pathogenetic pathways of ferritin regulation in RA require further study.

Correlation between levels of serum ferritin and lipid profile status.

Objectives: To analyse the correlation between ferritin level in serum and lipid profile in patients presenting to a Tertiary Care Centre. Study Design: Cross Sectional Descriptive study. Setting: Khyber Teaching Hospital Peshawar. Period: 1st January 2019 to 31st July 2019. Material & Methods: About 60 patients presenting to the laboratory referred for serum lipid profile or serum ferritin were included in the study. Sampling was done by purposive non probability technique. Blood was taken from patients in gel tube. Serum ferritin levels and lipid profile were done in all cases. Lipid profile included serum cholesterol, triglyceride level, low density lipoprotein and high density lipoproteins. The levels were recorded in a proforma. The serum ferritin level was correlated with the lipid profile status in all patient and the results were drawn accordingly. Results: About 60 patients were analysed. The mean age was 20.8± 5.2 years (range: 2 years to 60 years). There were 39 (65%) males and 21(35%) females. Out of 60 cases, serum ferritin level was normal, increased and lower in 15(25%), 40(66.6%) and 5 (8.3%) cases respectively. The cases where serum ferritin was abnormally raised, the significant changes in lipid profile were raised cholesterol and raised triglyceride (in 62.5% and 82.5% cases respectively). Conclusion: There is an association between raised serum ferritin and raised serum cholesterol level and serum triglyceride levels. This supports the link between serum ferritin regulation and lipid metabolism in the body. As dyslipidemia is a major cardiovascular risk factor. Therefore, a raised ferritin level must alert the physician about lipid profile of the patient and should prompt the physician to think about preventive measures against cardiovascular events in order to decrease the morbidity and mortality in patients at risk.

Impact of Autophagy and Aging on Iron Load and Ferritin in Drosophila Brain.

Biometals such as iron, copper, potassium, and zinc are essential regulatory elements of several biological processes. The homeostasis of biometals is often affected in age-related pathologies. Notably, impaired iron metabolism has been linked to several neurodegenerative disorders. Autophagy, an intracellular degradative process dependent on the lysosomes, is involved in the regulation of ferritin and iron levels. Impaired autophagy has been associated with normal pathological aging, and neurodegeneration. Non-mammalian model organisms such as Drosophila have proven to be appropriate for the investigation of age-related pathologies. Here, we show that ferritin is expressed in adult Drosophila brain and that iron and holoferritin accumulate with aging. At whole-brain level we found no direct relationship between the accumulation of holoferritin and a deficit in autophagy in aged Drosophila brain. However, synchrotron X-ray spectromicroscopy revealed an additional spectral feature in the iron-richest region of autophagy-deficient fly brains, consistent with iron–sulfur. This potentially arises from iron–sulfur clusters associated with altered mitochondrial iron homeostasis.

Phosphoinositide-3-kinase inhibition elevates ferritin level resulting depletion of labile iron pool and blocking of glioma cell proliferation

BackgroundElevated endogenous phosphoinositide-3-kinase (PI3K) activity is critical for cell proliferation in gliomas. Iron availability is one of the essential factors for cell growth and proliferation. However, any relation between PI3K and cellular iron homeostasis has not been understood so far. MethodsGlioma cells and human primary astrocytes were treated with class I PI3K inhibitors to examine regulation of iron homeostasis components. Regulation of ferritin was detected at mRNA and translational level. Labile iron pool (LIP) and cell proliferation were examined in glioma cells and human primary astrocytes. ResultsBlocking of PI3K activity elevated ferritin level by 6–10 folds in glioma cells by augmenting mRNA expression of ferritin subunits and also by influencing ferritin translation. IRE-IRP interaction was affected due to conversion of IRP1 to cytosolic aconitase that was influenced by increased iron-sulfur scaffold protein iron-sulfur cluster assembly enzyme (ISCU) level. Elevated ferritin sequestered LIP to affect cell proliferation that was reversed in silencing ferritin by siRNAs of ferritin-H and ISCU. Human primary astrocyte with little PI3K activity did not show any change in ferritin level, LIP and cell proliferation by PI3K inhibitors. ConclusionsPI3K inhibition promotes ferritin synthesis by dual mechanism resulting sequestration of iron to limit its availability for cell proliferation in glioma cells but not in primary astrocytes.General Significance: This observation establishes a relation between PI3K signalling and iron homeostasis in glioma cells. It also implies that activated PI3K controls ferritin expression to ensure availability of adequate iron required for cell proliferation.

Five Fibrosis Biomarkers Together with Serum Ferritin Level to Diagnose Liver Fibrosis and Cirrhosis.

Liver fibrosis is a dynamic procedure that results from an irregularity between fibrogenesis and fibrolysis. After time this procedure can lead to cirrhosis of the liver. Liver fibrosis and cirrhosis assessment is very important for both therapeutic decisions and prognostic evaluations. In this study, we tried to use serum ferritin (SF) together with five fibrosis tests (Age-Platelet index (API), aspartate aminotransferase to alanine aminotransferase ratio (AAR), AST to platelet ratio index (APRI), Fibrosis 4 score (FIB-4), and fibro-quotient (Fibro-Q)) to assess liver fibrosis and cirrhosis and estimate possible correlation between inflammation and SF. This study was carried out on eighty-eight patients infected with HCV and twenty healthy subjects as a control. Complete blood count (CBC), aspartate aminotransferase (AST), alanine aminotransferase (ALT), antiHCV antibody, detection of HCV RNA by real-time PCR, and serum ferritin (SF) were assessed. Then API, ARR, APRI, FIB-4, and Fibro-Q were calculated. Different fibrosis stages (mild fibrosis stage (F1), moderate fibrosis stage (F2), severe fibrosis stage (F3), cirrhotic stage (F4)) were assessed using transient elastography by Fibro Scan®. FIB-4 index was significantly elevated (p < 0.01) with the progression of liver fibrosis at F1, F2, F3, and F4 when compared to healthy control group. The APRI score elevation between F0 and F3 and between F0 and F4 was significant (p < 0.01). SF was elevated in all fibrosis stages and significantly (p < 0.01) at F3 and F4 compared to controls. APRI coupled with SF should be the best reliable biomarkers for liver cirrhosis. Simultaneously, from our data SF involved in all stages of inflammation. Therefore, down regulation of ferritin in the early stage of fibrosis should be helpful in decreasing the inflammatory effect of ferritin.

The Potential Role of Ferritin in Relation to Inflammatory and Metabolic Syndrome Biomarkers in Patients Undergoing Total Joint Arthroplasty of the Hip or Knee

Introduction: Maintaining proper iron regulation systemically is crucial in preserving systemic homeostasis. Ferritin is known to be a key component in this regulation by acting as a buffer via the controlled binding and releasing of iron. Ferritin is not only crucial in iron regulation, but it has also been observed to be a biomarker of inflammation. Considering this observation, it may be possible that ferritin plays a role in the pathogenesis of degenerative joint diseases (DJD). It has been identified that patients who had underwent total joint arthroplasty (TJA) procedure had increased serum levels of ferritin both pre-operatively and post-operatively. The rate of TJA procedures has been progressively increasing and it is projected that TJA procedures will increase to over 4 million procedures performed by 2030. In consideration of this observation, it is becoming increasingly important to gain a more comprehensive understanding in the pathology of DJD that require TJA procedure. The aim of this study is to examine the levels of ferritin in TJA patients pre-operatively and compare this level with those of other inflammatory and metabolic syndrome biomarkers in the patient samples while comparing the ferritin measurement to that of healthy controls.Study Design and Methods:After approval of the Institutional Review Board (IRB), pre-operative day one and post-operative day one blood samples of 45 TJA patients who underwent total knee arthroplasty (TKA) or total hip arthroplasty (THA) procedure were obtained as de-identified samples. Blood samples were collected into tubes containing 3.2% (0.109M) sodium citrate, plasma was then isolated. Control citrated plasma samples from non-smoking, drug-free, volunteers (age 18-35 years old) were obtained from from a certified vendor (George King Biomedical, Overland Park, KS). Plasma samples were stored at -80O C. The plasma samples were profiled for ferritin, C-peptide, insulin, IL-6, resistin, IL-1a, and PAI-1 utilizing a biochip array technology (RANDOX, Antrim, UK). All individual results were compiled as mean+1 SD and are summarized in the following table. The Mann-Whitney U test and the Spearman correlation test were used to analyze patient and control samples.Results:TableNormal Mean + standard deviationPre-op Mean + standard deviationPost-op Mean + standard deviationFerritin (ng/ml)68.44±74.23125.0±121.073.79±71.29C-peptide (ng/ml)3.22±2.5772.65±2.9863.40±3.64IL-6 (pg/ml)0.818±0.522827.18±41.1855.69±38.74Resistin (ng/ml)2.49±0.74065.34±4.9766.39±4.95Insulin (uIU/ml)20.77±19.0137.75±82.5841.39±77.53IL-1a (pg/ml)0.418±0.15070.663±0.78241.29±1.39PAI-1 (ng/ml)3.21±4.12714.98±9.83617.89±11.58There were significant increases in pre-operative levels of ferritin (p=0.0305), IL-6 (p<0.0001), resistin, (p<0.0001), IL-1a (p=0.0483), and PAI-1 (p<0.0001). There were insignificant alterations in the levels of C-peptide (decreased) and insulin (increased) in the pre-operative samples when compared with the healthy controls. Pre-operative correlations were observed between ferritin and each of the measured biomarkers; C-peptide (p=0.0043, R=0.324), IL-6 (p=0.00034, R=0.40), resistin (p=0.00043 R=0.394), insulin (p=0.00054, R=0.388), IL-1a (p=0.0256, R=-0.256), and PAI-1 (p<0.0001, R=0.460). Post-operative correlations were observed between ferritin and C-peptide (p=0.0008, R=0.529), as well as Insulin (p=0.0037, R=0.372). There was a correlation observed between pre-operative and post-operative levels of ferritin (p=0.0035, R=0.4943). Interestingly, the post-op values for ferritin dramatically decreased despite an increase in all other inflammatory and metabolic biomarkers.Conclusions:Understanding the factors that may affect ferritin regulation in TJA patients may be helpful in the management of DJD. Profiling inflammatory and metabolic syndrome biomarkers, including ferritin, may provide dynamic management options in the future that not only reduce adverse outcomes in these patients but also control the progression of degenerative processes. DisclosuresNo relevant conflicts of interest to declare.

Characterization of Anopheles gambiae (African Malaria Mosquito) Ferritin and the Effect of Iron on Intracellular Localization in Mosquito Cells.

Ferritin is a 24-subunit molecule, made up of heavy chain (HC) and light chain (LC) subunits, which stores and controls the release of dietary iron in mammals, plants, and insects. In mosquitoes, dietary iron taken in a bloodmeal is stored inside ferritin. Our previous work has demonstrated the transport of dietary iron to the ovaries via ferritin during oogenesis. We evaluated the localization of ferritin subunits inside CCL-125 [Aedes aegypti Linnaeus (Diptera: Culicidae), yellow fever mosquito] and 4a3b [Anopheles gambiae Giles (Diptera: Culicidae), African malaria mosquito] cells under various iron treatment conditions to further elucidate the regulation of iron metabolism in these important disease vectors and to observe the dynamics of the intracellular ferritin subunits following iron administration. Deconvolution microscopy captured 3D fluorescent images of iron-treated mosquito cells to visualize the ferritin HC and LC homologue subunits (HCH and LCH, respectively) in multiple focal planes. Fluorescent probes were used to illuminate cell organelles (i.e., Golgi apparatus, lysosomes, and nuclei) while secondary probes for specific ferritin subunits demonstrated abundance and co-localization within organelles. These images will help to develop a model for the biochemical regulation of ferritin under conditions of iron exposure, and to advance novel hypotheses for the crucial role of iron in mosquito vectors.

Mössbauer Study and Modeling of Iron Import and Trafficking in Human Jurkat Cells

The Fe content of Jurkat cells grown on transferrin-bound iron (TBI) and Fe(III) citrate (FC) was characterized using Mössbauer, electron paramagnetic resonance, and UV-vis spectroscopies, as well as electron and inductively coupled plasma mass spectrometry. Isolated mitochondria were similarly characterized. Fe-limited cells contained ~100 μM essential Fe, mainly as mitochondrial Fe and nonmitochondrial non-heme high-spin Fe(II). Cells replete with Fe also contained ferritin-bound Fe and Fe(III) oxyhydroxide nanoparticles. Only 400 ± 100 Fe ions were loaded per ferritin complex, regardless of the growth medium Fe concentration. Ferritin regulation thus appears to be more complex than is commonly assumed. The magnetic and structural properties of Jurkat nanoparticles differed from those of yeast mitochondria. They were smaller and may be located in the cytosol. The extent of nanoparticle formation scaled nonlinearly with the concentration of Fe in the medium. Nanoparticle formation was not strongly correlated with reactive oxygen species (ROS) damage. Cells could utilize nanoparticle Fe, converting such aggregates into essential Fe forms. Cells grown on galactose rather than glucose respired faster, grew slower, exhibited more ROS damage, and generally contained more nanoparticles. Cells grown with TBI rather than FC contained less Fe overall, more ferritin, and fewer nanoparticles. Cells in which the level of transferrin receptor expression was increased contained more ferritin Fe. Frataxin-deficient cells contained more nanoparticles than comparable wild-type cells. Data were analyzed by a chemically based mathematical model. Although simple, it captured essential features of Fe import, trafficking, and regulation. TBI import was highly regulated, but FC import was not. Nanoparticle formation was not regulated, but the rate was third-order in cytosolic Fe.

The association between the levels of serum ferritin and sex hormones in a large scale of Chinese male population.

BackgroundThe ferritin is an important participant of iron-storage but its regulation and related factors were not well defined. The present objective was to explore the potential association between serum ferritin levels and sex hormones.Methods1999 Chinese men in the Fangchenggang Area Male Health and Examination Survey (FAMHES) were recruited in this cross-sectional study. Levels of serum ferritin, total testosterone (free testosterone was calculated from the total one), estradiol and sex hormone-binding protein were detected in venous blood samples. The effects of age, BMI, smoking as well as alcohol consumption were analyzed on ferritin levels, respectively, and then the Pearson’s correlation analysis was used to evaluate the association between ferritin levels and sex hormones adjusting for the above factors.ResultsThe age, BMI and alcohol consumption significantly affected serum ferritin levels, but there was no significant difference between smokers and nonsmokers. Ferritin levels were significantly and negatively associated with total testosterone (R = −0.205, P< 0.001), sex hormone-binding protein (R = −0.161, P<0.001) and free testosterone (R = −0.097, P<0.001). After age and alcohol consumption were adjusted, the above associations were still significant (R = −0.200, −0.181 and −0.083, respectively, all P<0.001). However, there was only borderline negative association between ferritin levels and estradiol (adjusted R = −0.039, P = 0.083).ConclusionThe large scale of epidemic results showed the significantly negative associations between serum ferritin levels and sex hormones, which may provide more clues to explore the potential regulation and biological mechanism of ferritin.

Visualizing the Effect of Iron on the Localization of Intracellular Ferritin in Mosquito Cells

Ferritin is a 24‐subunit molecule, made up of heavy chain (HCH) and light chain (LCH) homologues that stores and controls the release of dietary iron in mammalian, plant, and insect systems. Dietary iron taken in a blood meal is stored inside ferritin, and previous work in mosquitoes demonstrates an important function for dietary iron in the process of egg development. One approach to limit the spread of arthropod‐borne diseases, such as yellow fever, West Nile virus and malaria, is to reduce the number of potential vectors by interfering with this process in mosquito reproduction and thereby to decrease transmission rates. The localization of ferritin subunits inside CCL‐125 (Aedes aegypti) and 4a3b (Anopheles gambiae) mosquito cells under various iron treatment conditions is important to further elucidate the regulation of iron metabolism in these important disease vectors and to observe the dynamics of intracellular ferritin subunits following iron administration. Deconvolution microscopy was used to capture 3D fluorescent images of treated mosquito cells to visualize the LCH ferritin subunit in multiple focal planes as a follow‐up to previous detection of the HCH subunit. Fluorescent probes were used to illuminate cell organelles (i.e. Golgi apparatus, lysosomes, endoplasmic reticulum, nuclei), while secondary probes for ferritin subunits demonstrated abundance and co‐localization within organelles. These images will help to develop a model for the biochemical regulation of ferritin, and perhaps to advance novel hypotheses for the crucial role of iron in mosquito reproduction. The Agricultural Experiment Station and the College of Agriculture and Life Sciences supported this research.

The effect of bacterial challenge on ferritin regulation in the yellow fever mosquito, Aedes aegypti.

Secreted ferritin is the major iron storage and transport protein in insects. Here, we characterize the message and protein expression profiles of yellow fever mosquito (Aedes aegypti) ferritin heavy chain homologue (HCH) and light chain homologue (LCH) subunits in response to iron and bacterial challenge. In vivo experiments demonstrated tissue-specific regulation of HCH and LCH expression over time post-blood meal (PBM). Transcriptional regulation of HCH and LCH was treatment specific, with differences in regulation for naïve versus mosquitoes challenged with heat-killed bacteria (HKB). Translational regulation by iron regulatory protein (IRP) binding activity for the iron-responsive element (IRE) was tissue-specific and time-dependent PBM. However, mosquitoes challenged with HKB showed little change in IRP/IRE binding activity compared to naïve animals. The changes in ferritin regulation and expression in vivo were confirmed with in vitro studies. We challenged mosquitoes with HKB followed by a blood meal to determine the effects on ferritin expression, and demonstrate a synergistic, time-dependent regulation of expression for HCH and LCH.

Visualization of ferritin in Anopheles gambiae 4a3b cells

Ferritin is a 24‐subunit molecule, made up of heavy and light chain proteins, that stores and controls the release of dietary iron in mammalian, plant, and insect systems. Previous work in mosquitoes demonstrates an important function of the dietary iron consumed in a blood meal and subsequently stored in ferritin in the process of egg development. One approach to limit the spread of arthropod borne diseases, such as yellow fever, West Nile virus and malaria, is to reduce the number of potential vectors by interfering with mosquito fecundity to decrease transmission rates. The localization of ferritin subunits inside mosquito cells under various treatment conditions is important to further elucidate the regulation of iron metabolism in this disease vector and to observe the dynamics of intracellular ferritin subunits following iron administration. Deconvolution microscopy was used to capture 3D fluorescent images of mosquito cells to visualize both ferritin subunits in multiple focal planes. Fluorescent probes illuminate cell organelles (i.e. Golgi apparatus, lysosomes, endoplasmic reticulum, nuclei, etc.) while secondary probes for both ferritin subunits demonstrate abundance and co‐localization within organelles. These images will help to develop a model for the biochemical regulation of ferritin and perhaps advance novel hypotheses for the crucial role of iron in mosquito reproduction. Research support from the Agricultural Experiment Station and the College of Agriculture and Life Sciences, the Undergraduate Biology Research Program and the Honors College at the University of Arizona.

Ferritin in Adult-Onset Still’s Disease: Just a Useful Innocent Bystander?

Background. Adult-Onset Still's Disease (AOSD) is an immune-mediated systemic disease with quotidian-spiking fever, rash, and inflammatory arthritis. Hyperferritinemia is a prominent feature, often used for screening. Methods. The key terms “ferritin” and “hyperferritinemia” were used to search PubMed and Medline and were cross-referenced with “Still's Disease.” Results. Hyperferritinemia, although nonspecific, is particularly prevalent in AOSD. While most clinicians associate ferritin with iron metabolism, this is mostly true for the H isoform and not for the L isoform that tends to increase dramatically in hyperferritenemia. In these situations, hyperferritinemia is not associated with iron metabolism and may even mask an underlying iron deficiency. We review, in systematic fashion, the current basic science and clinical literature regarding the regulation of ferritin and its use in the diagnosis and management of AOSD. Conclusion. Serum hyperferritinemia in AOSD has been described for 2 decades, although its mechanism has not yet been completely elucidated. Regulation by proinflammatory cytokines such as interleukin (IL)-1b, IL-6, IL-18, MCSF, and INF-α provides a link to the disease pathogenesis and may explain rapid resolution of hyperferritinemia after targeted treatment and inhibition of key cytokines.

The role of iron regulatory proteins in the control of iron metabolism in mammals

The iron regulatory proteins (IRP1 and IRP2) are two cytoplasmic RNA-binding proteins involved in the mechanisms that control iron metabolism in mammalian cells. They modulate the expression of iron-related proteins at a post-transcriptional level by binding to specific iron regulatory elements (IREs) on their mRNAs. IRP-IRE interaction can block protein synthesis or stabilize the mRNA. At low intracellular iron concentration, IRPs bind to the IRE of ferritin or ferroportin mRNAs and block their translation. Direct interactions between IRPs and several IRE motifs stabilize transferrin receptor mRNA. The converse regulation of ferritin and TfR synthesis, being a consequence of the lack of binding of IRPs to IRE, occurs in cells with high iron level. Thus, IRP-mediated regulation rapidly restores the physiological level of iron during its deficiency as well as excess. The role of IRPs in maintaining the intracelluar iron balance has been relatively well characterized in numerous types of mammalian cells. However, the importance of IRPs in the regulation of systemic iron metabolism in mammals, particularly, in signaling between the cells which play major roles in body iron metabolism, such as duodenal enterocytes, reticuloendothelial macrophages, hepatocytes, and bone marrow precursors of red blood cells, is only beginning to be investigated. Several studies have shown that IRP2 is a predominant regulator of iron homeostasis in mice housed under standard conditions, thus limiting the impact of IRP1 on this metabolic pathway. Although IRP1-deficient mice do not display a strong pathological phenotype, a deletion of both IRPs is embryonic lethal. In addition, in vitro and in vivo studies have reported that nitric oxide (NO) and hydrogen peroxide (H2O2), which are produced during inflammation, are potent IRP1 regulators that mediate the disassembly of Fe-S cluster of IRP1. There is also an increasing evidence that NO and superoxide anion (O2 ) may induce a strong down-regulation of IRP1 at the protein level and thus have an impact on the binding of IRP1 to IREs. All these data suggest a predominant role of IRP1 in the regulation of iron homeostasis under specific physiopathological conditions.

Transcriptional regulation of ferritin and antioxidant genes by HIPK2 under genotoxic stress

ATF1 (activating transcription factor 1), a stimulus-induced CREB family transcription factor, plays important roles in cell survival and proliferation. Phosphorylation of ATF1 at Ser63 by PKA (cAMP-dependent protein kinase) and related kinases was the only known post-translational regulatory mechanism of ATF1. Here, we found that HIPK2 (homeodomain-interacting protein kinase 2), a DNA-damage-responsive nuclear kinase, is a new ATF1 kinase that phosphorylates Ser198 but not Ser63. ATF1 phosphorylation by HIPK2 activated ATF1 transcription function in the GAL4-reporter system. ATF1 is a transcriptional repressor of ferritin H, the major intracellular iron storage gene, through an ARE (antioxidant-responsive element). HIPK2 overrode the ATF1-mediated ARE repression in a kinase-activity-dependent manner in HepG2 cells. Furthermore, DNA-damage-inducing agents doxorubicin, etoposide and sodium arsenite induced ferritin H mRNA expression in HIPK2(+/+) MEF cells, whereas it was significantly impaired in HIPK2(-/-) MEF cells. Induction of other ARE-regulated detoxification genes such as NQO1 (NADPH quinone oxidoreductase 1), GST (glutathione S-transferase) and HO1 (heme oxygenase 1) by genotoxic stress was also decreased in HIPK2-deficient cells. Taken together, these results suggest that HIPK2 is a new ATF1 kinase involved in the regulation of ferritin H and other antioxidant detoxification genes in genotoxic stress conditions.

The effect of bacterial challenge on ferritin regulation in Aedes aegypti

In mammals, ferritin is a cytoplasmic iron storage protein made up of 24 heavy and light chain subunits that can store up to 4500 iron atoms; as wells as an acute phase protein that is secreted upon inflammation. Here we characterize the message and protein expression profiles of Aedes aegypti (yellow fever mosquito) ferritin heavy chain (HCH) and light chain homologue (LCH) subunits in response to iron and bacterial challenge. Mosquito experiments show an increase in midgut HCH and LCH message and protein expression 24 h post‐blood meal (PBM) and decrease 72 h PBM. Fat body and ovary HCH and LCH message and protein expression showed a time‐dependent increase PBM. Heat‐killed bacteria (HKB) had little effect on mosquito tissue ferritin expression. Iron regulatory protein (IRP) binding activity for the iron responsive element (IRE) increased over time in ovary PBM. Midgut and fat body binding activity increased 24 h PBM with a decrease 72 h PBM. Mosquitoes treated with HKB showed no change in IRP/IRE binding activity compared to naïve animals. Cell studies support in vivo results. HCH and LCH message and protein expression reveal a time‐dependent, synergistic up‐regulation of expression in CCL‐125 cells treated with iron and HKB than iron alone. There was also a time‐dependent increase in secreted ferritin as well as decrease IRP/IRE binding activity in cells treated with iron and HKB. Research support from NIH (GM056812), the Agricultural Experiment Station and CALS at the University of Arizona.

Changes in Bioturbation of Iron Biogeochemistry and in Molecular Response of the Clam Ruditapes decussates upon Perkinsus olseni Infection

A series of artificial microcosms was used to test the effect of clam density on benthic iron biogeochemistry and, subsequently, if the response of clam Ruditapes decussatus to infection with Perkinsus olseni, a common opportunistic parasite known to be iron dependent, was correlated with the dynamics of iron sediment pore waters within the chambers. Three series of benthic microcosms were used in the experiment, comparing similar densities of clams (none, one, two, three, or four individuals/chamber) between a control set (no deliberate infection) and two parallel sets of clams that were deliberately infected with the parasite after 10 days of incubation. Fifteen chambers were used simultaneously and the experiment was conducted for 35 days. In order to avoid spurious effects of differential organic loading and clam feeding efficiency on the oxidative state of the sediment, the iron balance was tentatively shifted during incubation toward decreased dissolved iron in pore water. This was done by applying a constant flow of air to all chambers and refraining from supplying extra organic matter during the experimental run, which led to the reduction of benthic oxygen demand as the experiment progressed. Results showed that microcosms bearing both higher clam densities and lower infection levels were able to exert a quantitative influence in iron biogeochemistry through bioturbation activity. This effect was significantly depressed in chambers hosting clams with high infection levels. In addition, analysis of molecular markers responsive to iron and parasite stress revealed an upper regulation of HSP70 and ferritin in infected clams, thus suggesting a role of those molecules on both host protection and response to parasite presence by limiting iron availability. Together, these findings suggest a correlation between the expression of clam molecular iron/stress markers and iron bioavailability, which can be modified by the presence or absence of Perkinsus infection. In turn, we propose that clam lethargy in response to parasite invasion might help to combat infection by reducing iron mobilization in the surrounding sediment through a decrease in bioturbation activity, thus reducing its availability to the parasite.

Post-Translational Regulation of AtFER2 Ferritin in Response to Intracellular Iron Trafficking during Fruit Development in Arabidopsis

Ferritins are major players in plant iron homeostasis. Surprisingly, their overexpression in transgenic plants led only to a moderate increase in seed iron content, suggesting the existence of control checkpoints for iron loading and storage in seeds. This work reports the identification of two of these checkpoints. First, measurement of seed metal content during fruit development in Arabidopsis thaliana reveals a similar dynamic of loading for Fe, Mn, Cu, and Zn. The step controlling metal loading into the seed occurs by the regulation of transport from the hull to the seed. Second, metal loading and ferritin abundance were monitored in different genetic backgrounds affected in vacuolar iron transport (AtVIT1, AtNRAMP3, AtNRAMP4) or plastid iron storage (AtFER1 to 4). This approach revealed (1) a post-translational regulation of ferritin accumulation in seeds, and (2) that ferritin stability depends on the balance of iron allocation between vacuoles and plastids. Thus, the success of ferritin overexpression strategies for iron biofortification, a promising approach to reduce iron-deficiency anemia in developing countries, would strongly benefit from the identification and engineering of mechanisms enabling the translocation of high amounts of iron into seed plastids.

Deferoxamine-induced neurite outgrowth and synapse formation in postnatal rat dorsal root ganglion (DRG) cell cultures

Deferoxamine (DFO) was granted orphan drug status for the treatment of traumatic spinal cord injury but its neuroprotective mechanism is not well understood. We therefore investigated the mode of action of DFO in serum-starved and/or iron-stressed cultures of rat dorsal root ganglion (DRG) cells. We probed for redox signaling by determining hemeoxygenase-1 activity and by measuring expression of intracellular iron metabolism-related proteins under pro-oxidative conditions. We also employed DNA microarrays to better understand the genomic response of DRG cultures to treatment with DFO thereby enabling the generation of hypotheses. Essentially, DFO treatment resulted in outgrowth of neurofilament 200-positive neurites and induction of synapse formation as determined by immunoblotting, transmission electron microscopy and immunofluorescence confocal microscopy. Furthermore, DFO treatment of DRG cell cultures activated neuroprotective and antioxidative programs such as matrix metallopeptidase 2 and apolipoprotein D to promote neurite regeneration. Indeed, DFO reduced markedly reactive oxygen species formation, increased the expression of hemeoxygenase-1 and improved iron management through regulation of transferrin receptor and ferritin. We propose DFO treatment of DRG cell cultures to completely abolish the oxidative effect of ferrous iron (Fe 2+). Taken collectively, DFO reduced oxidative stress and induced synthesis of neuroprotective and antioxidative molecules to foster nerve repair and functional recovery. Our findings help to better understand the therapeutic benefit of DFO in the treatment of spinal cord injury.