Uptake of H-ferritin by Glioblastoma stem cells and its impact on their invasion capacity.

PURPOSE: Iron acquisition is key to maintaining cell survival and function. Cancer cells in general are considered to have an insatiable iron need. Iron delivery via the transferrin/transferrin receptor pathway has been the canonical iron uptake mechanism. Recently, however, our laboratory and others have explored the ability of ferritin, particularly the H-subunit, to deliver iron to a variety of cell types. Here, we investigate whether Glioblastoma (GBM) initiating cells (GICs), a small population of stem-like cells, are known for their iron addiction and invasive nature acquire exogenous ferritin, as a source of iron. We further assess the functional impact of ferritin uptake on the invasion capacity of the GICs. METHODS: To establish that H-ferritin can bind to human GBM, tissue-binding assays were performed on samples collected at the time of surgery. To interrogate the functional consequences of H-ferritin uptake, we utilized two patient-derived GIC lines. We further describe H-ferritin's impact on GIC invasion capacity using a 3D invasion assay. RESULTS: H-ferritin bound to human GBM tissue at the amount of binding was influenced by sex. GIC lines showed uptake of H-ferritin protein via transferrin receptor. FTH1 uptake correlated with a significant decrease in the invasion capacity of the cells. H-ferritin uptake was associated with a significant decrease in the invasion-related protein Rap1A. CONCLUSION: These findings indicate that extracellular H-ferritin participates in iron acquisition to GBMs and patient-derived GICs. The functional significance of the increased iron delivery by H-ferritin is a decreased invasion capacity of GICs potentially via reduction of Rap1A protein levels.

Tightly controlled response to oxidative stress; an important factor in the tolerance of Bacteroides fragilis.

The exposure of Bacteroides fragilis to highly oxygenated tissues induces an oxidative stress due to a shift from the reduced condition of the gastrointestinal tract to an aerobic environment of host tissues. The potent and effective responses to reactive oxygen species (ROS) make the B. fragilis tolerant to atmospheric oxygen for several days. The response to oxidative stress in B. fragilis is a complicated event that is induced and regulated by different agents. In this review, we will focus on the B. fragilis response to oxidative stress and present an overview of the regulators of responses to oxidative stress in this bacterium.

FtMt promotes glioma tumorigenesis and angiogenesis via lncRNA SNHG1/miR-9-5p axis.

OBJECTIVE: This study is to investigate the effects and the mechanisms of mitochondrial ferritin (FtMt) on the glioma tumorigenesis and angiogenesis. METHODS: FtMt expression was detected in glioma tissues and cells as well as in nude mouse tissues. Cell proliferation and apoptosis rate were observed following transfection of LV-FtMt or sh-FtMt in glioma cell line. Moreover, glioma cells with FtMt over-expression/knockdown were co-cultured with human umbilical vein endothelial cells (HUVECs) to observe its function on HUVEC proliferation, angiogenic ability and the vascular endothelial growth factor (VEGF) content. Gain and loss of function of small nucleolar RNA host gene 1 (SNHG1) and miR-9-5p were performed in glioma cells and GBM nude mice to observe its effect on glioma cell proliferation and HUVEC angiogenic ability. Luciferase reporter gene and RIP assay were employed to inspect the interactions among SNHG1, FtMt and miR-9-5p. Additionally, a xenograft mouse model was applied to determine the role of FtMt in glioma. RESULTS: In this work, FtMt was strongly expressed in glioma tissues and cells as well as in nude mouse tumor tissues. The employment of the loss-of and gain-of functions assays illustrated that FtMt enhanced glioma tumorigenesis and angiogenesis. Mechanistically, our findings showed that FtMt positively related to SNHG1 while negatively correlated with miR-9-5p, and both SNHG1 and FtMt can competitively bind with miR-9-5p. Besides, the inhibition effects of sh-FtMt on glioma were surveyed in vivo experiments. CONCLUSION: Evidence in this study suggested that FtMt promotes glioma tumorigenesis and angiogenesis via SNHG1 mediated miR-9-5p expression, which may provide a theoretical basis for glioma treatment.

Ferritinophagy is not required for colon cancer cell growth.

Ferritinophagy is a form of selective autophagy responsible for degrading intracellular ferritin, mediated by nuclear receptor coactivator 4 (NCOA4). NCOA4 plays significant roles in systemic iron homeostasis, and its disruption leads to simultaneous anemia and susceptibility to iron overload. The importance of iron colorectal cancer pathogenesis is well studied; however, the role of ferritinophagy in colon cancer cell growth has not been assessed. Disruption of ferritinophagy via NCOA4 knockout leads to only marginal differences in growth under basal and iron-restricted conditions. Moreover, NCOA4 played no significant role in cell death induced by 5-fluorouracil and erastin. Western blotting analysis for ferritin and transferrin receptor 1 found a dose-dependent effect on expression in both proteins in wild-type and NCOA4 knockout cell lines, but further investigation revealed no difference in growth response when treated at both high and low doses. Our data demonstrate a marginal role for ferritinophagy in growth both under normal and cytotoxic conditions in colon cancer cells, as well as a possible compensatory mechanism in colon cancer cells in response to ferroptosis induction.

Renal control of disease tolerance to malaria.

Malaria, the disease caused by Plasmodium spp. infection, remains a major global cause of morbidity and mortality. Host protection from malaria relies on immune-driven resistance mechanisms that kill Plasmodium However, these mechanisms are not sufficient per se to avoid the development of severe forms of disease. This is accomplished instead via the establishment of disease tolerance to malaria, a defense strategy that does not target Plasmodium directly. Here we demonstrate that the establishment of disease tolerance to malaria relies on a tissue damage-control mechanism that operates specifically in renal proximal tubule epithelial cells (RPTEC). This protective response relies on the induction of heme oxygenase-1 (HMOX1; HO-1) and ferritin H chain (FTH) via a mechanism that involves the transcription-factor nuclear-factor E2-related factor-2 (NRF2). As it accumulates in plasma and urine during the blood stage of Plasmodium infection, labile heme is detoxified in RPTEC by HO-1 and FTH, preventing the development of acute kidney injury, a clinical hallmark of severe malaria.

Screening and structural and functional investigation of a novel ferritin from Phascolosoma esculenta.

Ferritins are primary iron storage proteins and play a crucial role in iron storage and detoxification. Yeast two-hybrid method was employed to screen the cDNA library of Phascolosoma esculenta. Sequence of positive colony FER147 was analyzed. The higher similarity and conserved motifs for ferritin indicated that it belonged to a new member of ferritin family. The interaction between Ferritin and Fer147 was further confirmed through co-immunoprecipitation. The pET-28a-FER147 prokaryotic expression vector was constructed. The expressed recombinant Fer147 was then isolated, purified, and refolded. When ferritins were treated by different heavy metals, several detection methods, including scanning electron microscopy (SEM), circular dichroism (CD), and inductively coupled plasma-mass spectrometry (ICP-MS) were applied to examine the structures and functions of the new protein Fer147, recombinant P. esculenta ferritin (Rferritin), and natural horse-spleen ferritin (Hferritin). SEM revealed that the three ferritin aggregates changed obviously after different heavy metals treatment, meanwhile, a little different in aggregates were detected when the ferritins were trapped by the same heavy metal. Hence, changes in aggregation structure of the three proteins are related to the nature of the different heavy metals and the interaction between the heavy metals and the three ferritins. CD data suggested that the secondary structure of the three ferritins hardly changed after different heavy metals were trapped. ICP-MS revealed that the ferritins exhibit different enrichment capacities for various heavy metals. In particular, the enrichment capacity of the recombinant Fer147 and Rferritin is much higher than that of hferritin.

Physiological origin of biogenic magnetic nanoparticles in health and disease: from bacteria to humans.

The discovery of biogenic magnetic nanoparticles (BMNPs) in the human brain gives a strong impulse to study and understand their origin. Although knowledge of the subject is increasing continuously, much remains to be done for further development to help our society fight a number of pathologies related to BMNPs. This review provides an insight into the puzzle of the physiological origin of BMNPs in organisms of all three domains of life: prokaryotes, archaea, and eukaryotes, including humans. Predictions based on comparative genomic studies are presented along with experimental data obtained by physical methods. State-of-the-art understanding of the genetic control of biomineralization of BMNPs and their properties are discussed in detail. We present data on the differences in BMNP levels in health and disease (cancer, neurodegenerative disorders, and atherosclerosis), and discuss the existing hypotheses on the biological functions of BMNPs, with special attention paid to the role of the ferritin core and apoferritin.

Role of Bacterioferritin & Ferritin in M. tuberculosis Pathogenesis and Drug Resistance: A Future Perspective by Interactomic Approach.

Tuberculosis is caused by Mycobacterium tuberculosis, one of the most successful and deadliest human pathogen. Aminoglycosides resistance leads to emergence of extremely drug resistant strains of M. tuberculosis. Iron is crucial for the biological functions of the cells. Iron assimilation, storage and their utilization is not only involved in pathogenesis but also in emergence of drug resistance strains. We previously reported that iron storing proteins (bacterioferritin and ferritin) were found to be overexpressed in aminoglycosides resistant isolates. In this study we performed the STRING analysis of bacterioferritin & ferritin proteins and predicted their interactive partners [ferrochelatase (hemH), Rv1877 (hypothetical protein/probable conserved integral membrane protein), uroporphyrinogen decarboxylase (hemE) trigger factor (tig), transcriptional regulatory protein (MT3948), hypothetical protein (MT1928), glnA3 (glutamine synthetase), molecular chaperone GroEL (groEL1 & hsp65), and hypothetical protein (MT3947)]. We suggested that interactive partners of bacterioferritin and ferritin are directly or indirectly involved in M. tuberculosis growth, homeostasis, iron assimilation, virulence, resistance, and stresses.

Mitochondrial ferritin affects mitochondria by stabilizing HIF-1α in retinal pigment epithelium: implications for the pathophysiology of age-related macular degeneration.

Mitochondrial ferritin (FtMt) is believed to play an antioxidant role via iron regulation, and FtMt gene mutation has been reported in age-related macular degeneration (AMD). However, little is known about FtMt's functions in the retina and any links to AMD. In this study, we observed age-related increase in FtMt and hypoxia-inducible factor-1α (HIF-1α) in murine retinal pigment epithelium (RPE). FtMt overexpression in ARPE-19 cells stabilized HIF-1α, and increased the secretion of vascular endothelial growth factor. Conversely, HIF-1α stabilization reduced the protein level of the mature, functional form of FtMt. FtMt-overexpressing ARPE-19 cells exhibited less oxidative phosphorylation but unchanged production of adenosine triphosphate, enhanced mitochondrial fission, and triggered mitophagy in a HIF-1α-dependent manner. These findings suggest that increased FtMt in RPE may be protective via triggering mitophagy but cause wet AMD by inducing neovascularization due to increased vascular endothelial growth factor secretion. However, reduced level of functional FtMt in RPE under hypoxia may allow dry AMD through susceptibility to age-related stress.

Nuclear ferritin mediated regulation of JNK signaling in corneal epithelial cells.

Corneal epithelial (CE) cells are exposed to environmental insults (e.g., UV-irradiation), yet they suffer little damage. Our previous studies suggest that chicken CE cells have a novel form of protection involving having ferritin in a nuclear location where it can bind to DNA and sequester free iron. Here we describe another potential nuclear ferritin-mediated protective mechanism: the down-regulation of the JNK signaling pathway. The JNK pathway has been shown by others to promote apoptosis in response to cell damage and also to be activated in CE cell lines following exposure to UV radiation. Here we show in COS7 reporter cell lines that the expression of ferritin in a nuclear localization significantly down-regulates the JNK pathway (p = 5.7 × 10(-6)), but has no effect on the NFkB or the Erk pathways. In organ cultures of embryonic chicken corneas, we observed that inhibiting the synthesis of nuclear ferritin in CE cells, using the iron-chelating molecule deferoxamine, led to an increase in JNK signaling, as measured by phospho-JNK levels compared to CE cells with nuclear ferritin. Furthermore, the chemical inhibition of the JNK pathway using the molecule AS601245 decreased the production of nuclear ferritin. Taken together, these observations suggest that in CE cells a feedback-loop exists in which JNK signaling increases the production of nuclear ferritin and, in turn, nuclear ferritin decreases the activity of the JNK signaling pathway.

Identification of human ferritin, heavy polypeptide 1 (FTH1) and yeast RGI1 (YER067W) as pro-survival sequences that counteract the effects of Bax and copper in Saccharomyces cerevisiae.

Ferritin is a sub-family of iron binding proteins that form multi-subunit nanotype iron storage structures and prevent oxidative stress induced apoptosis. Here we describe the identification and characterization of human ferritin, heavy polypeptide 1 (FTH1) as a suppressor of the pro-apoptotic murine Bax sequence in yeast. In addition we demonstrate that FTH1 is a general pro-survival sequence since it also prevents the cell death inducing effects of copper when heterologously expressed in yeast. Although ferritins are phylogenetically widely distributed and are present in most species of Bacteria, Archaea and Eukarya, ferritin is conspicuously absent in most fungal species including Saccharomyces cerevisiae. An in silico analysis of the yeast proteome lead to the identification of the 161 residue RGI1 (YER067W) encoded protein as a candidate for being a yeast ferritin. In addition to sharing 20% sequence identity with the 183 residue FTH1, RGI1 also has similar pro-survival properties as ferritin when overexpressed in yeast. Analysis of recombinant protein by SDS-PAGE and by electron microscopy revealed the expected formation of higher-order structures for FTH1 that was not observed with Rgi1p. Further analysis revealed that cells overexpressing RGI1 do not show increased resistance to iron toxicity and do not have enhanced capacity to store iron. In contrast, cells lacking RGI1 were found to be hypersensitive to the toxic effects of iron. Overall, our results suggest that Rgi1p is a novel pro-survival protein whose function is not related to ferritin but nevertheless it may have a role in regulating yeast sensitivity to iron stress.

Ferritins: furnishing proteins with iron.

Ferritins are a superfamily of iron oxidation, storage and mineralization proteins found throughout the animal, plant, and microbial kingdoms. The majority of ferritins consist of 24 subunits that individually fold into 4-α-helix bundles and assemble in a highly symmetric manner to form an approximately spherical protein coat around a central cavity into which an iron-containing mineral can be formed. Channels through the coat at inter-subunit contact points facilitate passage of iron ions to and from the central cavity, and intrasubunit catalytic sites, called ferroxidase centers, drive Fe(2+) oxidation and O2 reduction. Though the different members of the superfamily share a common structure, there is often little amino acid sequence identity between them. Even where there is a high degree of sequence identity between two ferritins there can be major differences in how the proteins handle iron. In this review we describe some of the important structural features of ferritins and their mineralized iron cores, consider how iron might be released from ferritins, and examine in detail how three selected ferritins oxidise Fe(2+) to explore the mechanistic variations that exist amongst ferritins. We suggest that the mechanistic differences reflect differing evolutionary pressures on amino acid sequences, and that these differing pressures are a consequence of different primary functions for different ferritins.

Antisense transcription regulates the expression of the enterohemorrhagic Escherichia coli virulence regulatory gene ler in response to the intracellular iron concentration.

Enteric pathogens, such as enterohemorrhagic E. coli (EHEC) O157:H7, encounter varying concentrations of iron during their life cycle. In the gastrointestinal tract, the amount of available free iron is limited because of absorption by host factors. EHEC and other enteric pathogens have developed sophisticated iron-responsive systems to utilize limited iron resources, and these systems are primarily regulated by the Fur repressor protein. The iron concentration could be a signal that controls gene expression in the intestines. In this study, we explored the role of iron in LEE (locus for enterocyte effacement) virulence gene expression in EHEC. In contrast to the expression of Fur-regulated genes, the expression of LEE genes was greatly reduced in fur mutants irrespective of the iron concentration. The expression of the ler gene, the LEE-encoded master regulator, was affected at a post-transcription step by fur mutation. Further analysis showed that the loss of Fur affected the translation of the ler gene by increasing the intracellular concentration of free iron, and the transcription of the antisense strand was necessary for regulation. The results indicate that LEE gene expression is closely linked to the control of intracellular free iron homeostasis.

Iron deficiency anemia: a common and curable disease.

Iron deficiency anemia arises when the balance of iron intake, iron stores, and the body's loss of iron are insufficient to fully support production of erythrocytes. Iron deficiency anemia rarely causes death, but the impact on human health is significant. In the developed world, this disease is easily identified and treated, but frequently overlooked by physicians. In contrast, it is a health problem that affects major portions of the population in underdeveloped countries. Overall, the prevention and successful treatment for iron deficiency anemia remains woefully insufficient worldwide, especially among underprivileged women and children. Here, clinical and laboratory features of the disease are discussed, and then focus is placed on relevant economic, environmental, infectious, and genetic factors that converge among global populations.

Ferritin is the key to dietary iron absorption and tissue iron detoxification in Drosophila melanogaster.

Mammalian ferritin is predominantly in the cytosol, with a minor portion found in plasma. In most insects, including Drosophila melanogaster, ferritin belongs to the secretory type. The functional role of secretory ferritin in iron homeostasis remains poorly understood in insects as well as in mammalians. Here we used Drosophila to dissect the involvement of ferritin in insect iron metabolism. Midgut-specific knockdown of ferritin resulted in iron accumulation in the gut but systemic iron deficiency (37% control), accompanied by retarded development and reduced survival (3% survival), and was rescued by dietary iron supplementation (50% survival) or exacerbated by iron depletion (0% survival). These results suggest an essential role of ferritin in removing iron from enterocytes across the basolateral membrane. Expression of wild-type ferritin in the midgut, especially in the iron cell region, could significantly rescue ferritin-null mutants (first-instar larvae rescued up to early adults), indicating iron deficiency as the major cause of early death for ferritin flies. In many nonintestinal tissues, tissue-specific ferritin knockdown also caused local iron accumulation (100% increase) and resulted in severe tissue damage, as evidenced by cell loss. Overall, our study demonstrated Drosophila ferritin is essential to two key aspects of iron homeostasis: dietary iron absorption and tissue iron detoxification.

Mitochondrial ferritin attenuates ß-amyloid-induced neurotoxicity: reduction in oxidative damage through the Erk/P38 mitogen-activated protein kinase pathways.

AIMS: Mitochondrial ferritin (MtFt), which was recently discovered, plays an important role in preventing neuronal damage in 6-hydroxydopamine-induced Parkinsonism by maintaining mitochondrial iron homeostasis. Disruption of iron regulation also plays a key role in the etiology of Alzheimer's disease (AD). To explore the potential neuroprotective roles of MtFt, rats and cells were treated with Aß(25-35) to establish an AD model. RESULTS: We report that knockdown of MtFt expression significantly enhanced Aß(25-35)-induced neurotoxicity as shown by dysregulation of iron homeostasis, enhanced oxidative stress, and increased cell apoptosis. Opposite results were obtained when MtFt was overexpressed in SH-SY5Y cells prior to treatment with Aß(25-35). Further, MtFt inhibited Aß(25-35)-induced P38 mitogen-activated protein kinase and activated extracellular signal-regulated kinase (Erk) signaling. INNOVATION: MtFt attenuated Aß(25-35)-induced neurotoxicity and reduced oxidative damage through Erk/P38 kinase signaling. CONCLUSION: Our results show a protective role of MtFt in AD and suggest that regulation of MtFt expression in neuronal cells may provide a new neuroprotective strategy for AD.

[Vitamin B12 and iron deficiencies: from diagnostic to follow-up]. / Carences en vitamine B12 et fer: du diagnostic au suivi.

Vitamin B12 and iron deficiencies are common problems in consultations of general internal medicine. They cause different symptoms that can be non-specific. This article makes it possible, from a clinical frame of reference, to answer the following questions: What value of vitamin B12 should we consider a "deficiency", and what is the role of methylmalonate? What is the role of vitamin B12 oral supplements? How should we interpret values of ferritine? How should iron deficiency be investigated? What is the place of intravenous iron administration?

Can serum ferritin, vitamin B(12) and folic acid levels affect serum screening tests during pregnancy?

OBJECTIVE: To examine the relation of serum folate, vitamin B(12) and ferritin levels to 1st and 2nd trimester serum screening markers. METHODS: Fetal crown-rump length (CRL), nuchal translucency (NT), and first and second trimester serum screening tests of 228 pregnant women were obtained. In all cases, serum vitamin B(12), folic acid and ferritin levels were analyzed during the 11-14 week period. Levels below <15 µg/L, 3 ng/mL and 211 pg/mL were accepted as nutrient deficiency for serum ferritin, folic acid and vitamin B(12), respectively. Results of serum screening markers of women below and above these values were compared with each other. RESULTS: Comparison of groups with ferritin levels <15 and >15 µg/L for 1st and 2nd trimester serum screening parameters revealed significant differences between groups in terms of pregnancy associated plasma protein-A (PAPP-A), free ß-human chorionic gonadotropin (fb-hCG), AFP and hCG. Comparison of women with low versus normal B(12) levels revealed significant differences in terms of NT, PAPP-A and fb-hCG. CONCLUSION: Although sufficient, number of cases is limited in this study so results cannot be generalized to all population. It could be advised that in addition to folic acid supplementation, deficiencies of ferritin and B(12) must be corrected in patients considering pregnancy or early 1st trimester pregnant women to obtain more accurate serum screening results.

The two Dps of Edwardsiella tarda are involved in resistance against oxidative stress and host infection.

DNA-binding protein from starved cells (Dps) is a member of ferritin-like proteins that exhibit properties of nonspecific DNA binding and iron oxidation and storage. Although studies of Dps from many bacterial species have been reported, no investigations on Dps from fish pathogens have been documented. In this study, we examined the biological function of two Dps proteins, Dps1 and Dps2, from Edwardsiella tarda, an important fish bacterial pathogen that can also infect humans. Dps1 and Dps2 are, respectively, 163- and 174-residue in length and each contains the conserved ferroxidase center of Dps. Expression of dps1 and dps2 was growth phase-dependent and reached high levels in stationary phase. Purified recombinant Dps1 and Dps2 were able to mediate iron oxidation by H(2)O(2) and bind DNA. Compared to the wild type strain, (i) the dps1 mutant (TXDps1) and the dps2 mutant (TXDps2) were unaffected in growth, while the dps2 mutant with interfered dps1 expression (TXDps2RI) exhibited a prolonged lag phase; (ii) TXDps1, TXDps2, and especially TXDps2RI were significantly reduced in H(2)O(2) and UV tolerance and impaired in the capacity to invade into host tissues and replicate in head kidney macrophages; (iii) TXDps1, TXDps2, and TXDps2RI induced stronger macrophage respiratory burst activity and thus were defective in the ability to block the bactericidal response of macrophages. Taken together, these results indicate that Dps1 and Dps2 are functional analogues that possess ferroxidase activity and DNA binding capacity and are required for optimum oxidative stress resistance and full bacterial virulence.