Ferroportin Research Articles

Similar Ferroportin Q248H polymorphism prevalence in patients with Plasmodium falciparum malaria and control subjects in the low-endemic setting of Botswana

IntroductionRecent evidence suggests that ferroportin (FPN) Q248H may confer a survival advantage against malaria by reducing erythrocytic intracellular iron in Africans. We investigated if FPN Q248H mutation, that is prevalent in Batswana, is a factor in limiting the susceptibility to Plasmodium falciparum malaria. Methods264 archived dried blood spot samples (183 P. falciparum malaria cases and 81 controls, matched for geographical region and season for equal exposure) were genotyped. Human and P. falciparum DNA was extracted using Chelex-100 resin and P. falciparum molecular confirmation performed. Ferroportin Q248H mutation was identified by restriction fragment length polymorphism. The prevalence of the FPN Q248H mutation and allele frequency and the accompanying 95% confidence interval were calculated. A qPCR method was employed to estimate P. falciparum parasitaemia. Association between FPN and malaria susceptibility was tested using Pearson Chi-square test and Mood's median test was used to compare P. falciparum parasitaemias according to FPN Q248H mutation. ResultsAll samples were successfully genotyped. The FPN Q248H allele frequency was 0.08 (95% CI: 0.05–0.11) in cases and 0.08 (95% CI: 0.02–0.14) in controls, consistent with Hardy-Weinberg equilibrium. The prevalence of FPN Q248H phenotype was comparable in patients with P. falciparum malaria and in un-infected individuals, 16.4% (95% CI: 11.0–21.8) vs 14.8% (95% CI: 7.1–22.5), P = 0.746. In addition, no association of presence of FPN Q248H with reduced parasitaemia was recorded, P = 0.837. ConclusionIn this small study, FPN Q248H polymorphism prevalence was comparable between patients with P. falciparum malaria and control subjects in the low-endemic setting of Botswana.

An SMVT-targeting and peroxynitrite-activating fluorescent probe for head and neck cancer imaging and peroxynitrite detection

Head and neck squamous cell carcinoma (HNSCC) is the 6th most common cancer worldwide. For better diagnosis and precise resection of HNSCC, Fluorescent probe has been developed as an ideal tool to visualize tumor sites and to detect biological molecules. However, the targeting strategies of small molecular probes are limited. We designed probe RB-PN (Rhodamine biotin-peroxynitrite) with both sodium-dependent multivitamin transporter (SMVT)-targetable and peroxynitrite (ONOO−)-activatable tumor-targeting strategies. It can detect ONOO− with high specificity and selectivity, and rapid response. Besides, it exhibits prominent imaging abilities with enhanced accumulation by SMVT-transportation. The remarkable sensitivity, selectivity, turn-on signal change and rapid responsive time have been identified. We evidenced the dual-targeting strategy, and applied it in tumor visualization and ONOO− detection both in HNSCC cells and in vivo. We also identified the potential application of it in cytokine therapy using 3D micro-spheroid models. We expect RB-PN with a dual-targeting strategy could be conducive to the diagnosis of tumor pre-operatively or even intra-operatively.

Prepregnancy Obesity Does Not Impact Placental Iron Trafficking

BackgroundIron is critical for fetal development. Neonates of obese women may be at risk for poor iron status at birth as a result of maternal inflammation-driven overexpression of hepcidin. ObjectivesThe objective of this study was to determine differences in placental transfer of oral iron (57Fe) and expression of placental transferrin receptor 1 (TFR1) and ferroportin (FPN) mRNA and protein and their association with maternal and neonatal iron-related parameters, including maternal hepcidin, among women with and without prepregnancy (PP) obesity. Methods57Fe ingested during the third trimester of pregnancy was recovered in venous umbilical cord blood among 20 PP obese [BMI (in kg/m2): 30.5–43.9] and 22 nonobese (BMI: 18.5–29.0) women aged 17–39 y. Placental TFR1 and FPN mRNA and protein expression were quantified via qPCR and Western blot. Maternal and neonatal markers of iron status and regulation, as well as inflammation, were measured. Descriptive and inferential statistical tests (e.g., Student t test, Pearson correlation) were used for data analysis. ResultsThere was no difference in cord blood enrichment of 57Fe or placental mRNA or protein expression of TFR1 or FPN among the women with and without PP obesity. Maternal hepcidin was not correlated with cord blood enrichment of 57Fe or placental FPN mRNA or protein expression. Maternal log ferritin (corrected for inflammation) was inversely correlated with log percent enrichment of 57Fe in cord blood (partial r = –0.50; P < 0.01, controlled for marital status) and protein expression of TFR1 (r = –0.43; P = 0.01). ConclusionsPlacental iron trafficking did not differ among women with and without PP obesity. Findings reinforce the importance of maternal iron stores in regulating placental iron trafficking.

Folic Acid Absorption Characteristics and Effect on Cecal Microbiota of Laying Hens.

This experiment was conducted to investigate the characteristics of folic acid (FA) absorption in laying hens and the effect of FA supplementation on cecal microbiota. A total of 432 healthy hens (30-week-old) were randomly assigned to four diets supplemented with FA: 0, 1, 6, and 24 mg/kg of feed for 8 w. Blood, duodenum, jejunum, ileum, cecum, and cecal chyme samples (six samples per treatment) were collected from the hens at the end of the feeding trial. Expression profiles of folate transport and transformation genes in intestine and cecal microbiota were detected. Results showed that serum folate level significantly increased (P < 0.01) with an increase in dietary FA supplementation, reaching a plateau at 6 mg/kg FA supplementation. The expression of FA transport and transformation genes was not affected in the cecum (P > 0.05) by dietary FA supplementation; however, it was affected in the duodenum, jejunum, and ileum and mostly showed a downward trend in treatment groups (P < 0.05). The genes affected include duodenal folate receptor (Folr) and dihydrofolate reductase (Dhfr), jejunal proton-coupled folate transporter (Pcft) and reduced folate carrier (Rfc), and ileal ATP binding cassette subfamily C member (Abcc2), Abcc3, Rfc, Folr, and Dhfr. Furthermore, according to the operational taxonomic unit classification and taxonomic position identification, the cecal microbiota population of the hens was not affected by dietary FA supplementation at the phylum, class, order, family, genus, and species levels (P > 0.05). However, the relative abundance of some microbiota was affected by dietary FA supplementation (P < 0.05). In conclusion, FA transport from the intestinal lumen into enterocytes, and then into the bloodstream, is strictly regulated, which may be associated with the regulation of the expression profiles of genes involved in FA absorption. Pathogenic bacteria decreased in the cecum, especially at 24 mg/kg supplementation, but the beneficial bacteria (Bifidobacteriaceae) decreased at this level, too. Overall, FA supplementation at 6 mg/kg, which was selected for folate-enriched egg production, did not affect the health and metabolism of laying hens negatively.

Dysregulated zinc and sphingosine-1-phosphate signaling in pulmonary hypertension: Potential effects by targeting of bone morphogenetic protein receptor type 2 in pulmonary microvessels.

Recently identified molecular targets in pulmonary artery hypertension (PAH) include sphingosine-1-phosphate (S1P) and zinc transporter ZIP12 signaling. This study sought to determine linkages between these pathways, and with BMPR2 signaling. Lung tissues from a rat model of monocrotaline-induced PAH and therapeutic treatment with bone marrow-derived endothelial-like progenitor cells transduced to overexpress BMPR2 were studied. Multifluorescence quantitative confocal microscopy (MQCM) was applied for analysis of protein expression and localization of markers of vascular remodeling (αSMA and BMPR2), parameters of zinc homeostasis (zinc transporter SLC39A/ZIP family members 1, 10, 12 and 14; and metallothionein MT3) and S1P extracellular signaling (SPHK1, SPNS2, S1P receptor isoforms 1, 2, 3, 5) in 20-200 µm pulmonary microvessels. ZIP12 expression in whole lung tissue lysates was assessed by western blot. Spearman nonparametric correlations between MQCM readouts and hemodynamic parameters, Fulton index (FI), and right ventricular systolic pressure (RVSP) were measured. In line with PAH status, pulmonary microvessels in monocrotaline-treated animals demonstrated significant (p < .05, n = 6 per group) upregulation of αSMA (twofold) and downregulation of BMPR2 (20%). Upregulated ZIP12 (92%), MT3 (57.7%), S1PR2 (54.8%), and S1PR3 (30.3%) were also observed. Significant positive and negative correlations were demonstrated between parameters of zinc homeostasis (ZIP12, MT3), S1P signaling (S1PRs, SPNS2), and vascular remodeling (αSMA, FI, RVSP). MQCM and western blot analysis showed that monocrotaline-induced ZIP12 upregulation could be partially negated by BMPR2-targeted therapy. Our results indicate that altered zinc transport/storage and S1P signaling in the monocrotaline-induced PAH rat model are linked to each other, and could be alleviated by BMPR2-targeted therapy.

Autophagy Inhibition Plays a Protective Role in Ferroptosis Induced by Alcohol via the p62-Keap1-Nrf2 Pathway.

Binge alcohol consumption is a serious health concern. Ferroptosis is an iron-dependent lipid peroxidation mediated cell death. Activation of the Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) pathway has been shown to exert a protective effect by blunting the responses to ferroptosis inducers. The autophagy substrate p62 was demonstrated to modulate Nrf2 and contribute to the suppression of ferroptosis. Furthermore, autophagy inhibition resulted in the accumulation of p62, which is a specific substrate for this process. Therefore, we aimed to explore the protective effect of autophagy inhibition against alcohol-induced ferroptosis through activating the p62-Keap1-Nrf2 pathway. Our results demonstrated that alcohol induced ferroptosis, which could be significantly reduced by ferrostatin-1. Additionally, we found that autophagy inhibition could protect HepG2 cells against alcohol-induced ferroptosis by activating the p62-Keap1-Nrf2 pathway. Furthermore, inhibition of autophagy increased the expression of p62, which interacted with Keap1 to promote Nrf2 translocation into the nucleus and upregulation its target proteins ferritin heavy (FTH), ferroportin (FPN), and heme oxygenase-1 (HO-1). This study provides a theoretical basis for further elucidation of the relationship between autophagy and ferroptosis and lays a preliminary foundation for further research concerning dietary guidance in the prevention and treatment of diseases related to alcohol-induced ferroptosis.

Gene Expression Changes in Epinephelus marginatus (Teleostei, Serranidae) Liver as Molecular Biomarker of Iron Ore Contamination.

The aim of this study was to determine selected molecular biomarkers of iron ore contamination in Epinephelus marginatus. Molecular biomarkers were tested by checking the relative expression of genes involved in oxidative stress, trace element regulation, and cellular damage, by RT-qPCR. Iron ore exposure caused the downregulation of ferroportin (FP) gene expression and a significant upregulation in superoxide dismutase (SOD) and cytochrome P450 1A (CYP1A) genes. Iron ore affects gene expression in E. marginatus liver, indicating that it can potentially induce toxic effects in fish. Moreover, this altered gene expression pattern may be applied in monitoring iron ore contamination in marine environments.

Iron regulatory protein 1 promotes ferroptosis by sustaining cellular iron homeostasis in melanoma.

Melanoma, the most aggressive skin cancer, is mainly treated with BRAF inhibitors or immunotheareapy. However, most patients who initially responded to BRAF inhibitors or immunotheareapy become resistant following relapse. Ferroptosis is a form of regulated cell death characterized by its dependence on iron ions and the accumulation of lipid reactive oxygen species (ROS). Recent studies have demonstrated that ferroptosis is a good method for tumor treatment, and iron homeostasis is closely associated with ferroptosis. Iron regulatory protein (IRP)1 and 2 play important roles in maintaining iron homeostasis, but their functions in ferroptosis have not been investigated. The present study reported that the expression of IRP1 and IRP2 was increased by the ferroptosis inducers erastin and RSL3 in melanoma cells. Depletion of IRP1 significantly suppressed erastin- and RSL3-induced ferroptosis. IRP2 had a weak effect but could enhance the promoting function of IRP1 on ferroptosis. Further, erastin and RSL3 promoted the transition of aconitase 1 to IRP1, which regulated downstream iron metabolism proteins, including transferrin receptor (TFRC), ferroportin (FPN) and ferritin heavy chain 1 (FTH1). Moreover, overexpression of TFRC and knockdown of FPN and FTH1 significantly promoted erastin- and RSL3-induced ferroptosis in IRP1 knockdown melanoma cells. Collectively, the present findings indicate that IRP1 plays an essential role in erastin- and RSL3-induced ferroptosis by regulating iron homeostasis.

Immunochemical analysis of iron transporters and M2 macrophages in ovarian endometrioma and clear cell adenocarcinoma.

The association between iron ions and endometriosis-associated ovarian cancer (EAOC) has been previously investigated to elucidate EAOC carcinogenesis; however, the dynamics of iron deposition in the endometrial epithelium and endometrial stroma of ovarian endometrioma (OE) remains unknown. The present study aimed to determine the expression of iron transporters on the cell surface and the distribution of tumor-associated macrophages (TAMs) englobed with iron in the endometrial stroma. The current retrospective study investigated 20 OE and 18 ovarian clear cell adenocarcinoma (CCC) samples, using Perls Prussian blue staining and immunohistochemistry of iron transporters, including divalent metal transporter 1 (DMT1), transferrin receptor (TfR) and ferroportin (FPN). Additionally, samples were stained for CD68, CD11c, CD163 and CD206, and double-immunostained for iron and CD163 to define the distribution of macrophages. Iron transporters were identified on the endometrial epithelium of OE and CCC tumor cells, and TAMs were englobed with iron in the endometrial stroma of OE and CCC. Histological findings revealed DMT1 upregulation in OE and CCC, whereas lower TfR and FPN expression was observed in OE than in CCC. M2 macrophages were englobed with iron ions in the deep layers of the OE and CCC stroma. The endometrial epithelium located in the endometrial stroma of one patient with OE and the endometrial epithelium adjacent to CCC in two patients with CCC stained positive for the tumor proliferation marker Ki67. Epithelium infiltrating the stroma of OE may become the origin of cancer under the influence of M2 macrophages englobed with iron. These findings provide new perspectives on the malignant transformation of OE into EAOC and its possibility as a precancerous index.

Hepcidin contributes to Swedish mutant APP-induced osteoclastogenesis and trabecular bone loss

Patients with Alzheimer’s disease (AD) often have lower bone mass than healthy individuals. However, the mechanisms underlying this change remain elusive. Previously, we found that Tg2576 mice, an AD animal model that ubiquitously expresses Swedish mutant amyloid precursor protein (APPswe), shows osteoporotic changes, reduced bone formation, and increased bone resorption. To understand how bone deficits develop in Tg2576 mice, we used a multiplex antibody array to screen for serum proteins that are altered in Tg2576 mice and identified hepcidin, a master regulator of iron homeostasis. We further investigated hepcidin’s function in bone homeostasis and found that hepcidin levels were increased not only in the serum but also in the liver, muscle, and osteoblast (OB) lineage cells in Tg2576 mice at both the mRNA and protein levels. We then generated mice selectively expressing hepcidin in hepatocytes or OB lineage cells, which showed trabecular bone loss and increased osteoclast (OC)-mediated bone resorption. Further cell studies suggested that hepcidin increased OC precursor proliferation and differentiation by downregulating ferroportin (FPN) expression and increasing intracellular iron levels. In OB lineage cells, APPswe enhanced hepcidin expression by inducing ER stress and increasing OC formation, in part through hepcidin. Together, these results suggest that increased hepcidin expression in hepatocytes and OB lineage cells in Tg2576 mice contributes to enhanced osteoclastogenesis and trabecular bone loss, identifying the hepcidin-FPN-iron axis as a potential therapeutic target to prevent AD-associated bone loss.

Folate Transporters Are Found Throughout the Colon of Humans and Their mRNA Expression Appears to Be Unaffected by Low Dose Folic Acid Supplementation

ObjectivesA large depot of folate resides in the colon and can exceed dietary intake. Little is known about the capacity of the colon to absorb folate. We aimed to determine the expression of key folate transporters, reduced folate carrier (RFC) and proton-coupled folate transporter (PCFT), throughout the colon of healthy adults and the impact of low dose folic acid (FA) supplementation. MethodsIn this 16 wk open-labelled randomized control trial, healthy adults (n = 25) from a colonoscopy waiting list were randomized to receive daily a multivitamin plus a 400 μg FA (400FA, n = 12) or no FA supplement (0FA, n = 13). Subjects were provided with low FA bread and pasta and instructions how to follow a low FA containing diet. Six 24-hr diet recalls were administered throughout the study and blood samples were collected at baseline, 8 and 16 wk. At colonoscopy (16 wk), 4 tissue biopsies were collected from the terminal ileum, cecum, ascending and descending colon. Blood folates were determined by microbial assay; mRNA levels of folate transporters were assessed using qPCR. ResultsOne subject was removed from analysis due to missing data (0FA). No group differences in age, sex, BMI, dietary intake, vitamin B12, red blood cell (RBC) and plasma folate levels at baseline were observed. Mean ± SD FA supplement adherence was 92 ± 12% and 96 ± 9% at 8 and 16 wk, respectively. Subjects in the 400FA group had higher total folate intake (P < 0.05) and higher RBC and plasma folate levels (P < 0.01) at 8 and 16 wk compared to 0FA subjects. RBC values at 16 wk were 1764 ± 636 and 865 ± 190 nmol/L in the 400FA and 0FA group, respectively. RFC and PCFT were detected in terminal ileum and colon biopsies (n = 96) and their mRNA levels in each section did not differ between groups. However, expression of RFC was markedly higher than PCFT across all biopsy sections (P < 0.05) and highest in the terminal ileum, compared to the cecum, ascending and descending colon in both groups (P < 0.05). ConclusionsWe demonstrated expression of folate transporters, RFC and PCFT, throughout the human colon suggesting their potential contribution to overall folate absorption. mRNA expressions were not affected by a low dose FA supplement. A deeper understanding of how FA and folate status affect colonic transporter regulation may inform future revisions of folate intake recommendations. Funding SourcesNatural Sciences and Engineering Research Council.

Localization of the Folate Transport Systems in the Murine Central Nervous System

ObjectivesFolates are critical for normal neurodevelopment, and folate transport in the brain is primarily mediated by folate receptor alpha (FRα) at the blood-cerebrospinal fluid barrier (BCSFB). However, studies have reported folate transporter/receptor expression in other brain compartments, which may significantly contribute to overall brain folate uptake. The objective of this study is to characterize the localization of the folate transport systems i.e., reduced folate carrier (RFC), proton-coupled folate transporter (PCFT), and FRα in the mouse central nervous system, which will provide insight on novel routes of brain folate transport. In particular, folate transporter/receptor localization is examined at brain barriers [blood-brain barrier (BBB), BCSFB, arachnoid barrier (AB)] and in brain parenchyma (astrocytes, microglia, neurons). MethodsThe localization of RFC, PCFT and FRα was observed in the brains of C57BL6/N wildtype mice by applying immunohistochemistry (IHC). Mouse brains were isolated, and IHC was performed on frozen coronal sections. Transporter/receptor localization was examined at brain barriers (BBB, BCSFB, AB) and in brain parenchyma (astrocytes, neurons, microglia) using specific antibodies. Standard IHC markers were utilized to identify various brain compartments, with confocal microscopy used for imaging. ResultsAt the mouse BBB and BCSFB, localization of RFC, PCFT and FRα was observed, which is consistent with previous reported data and our own work. At the AB, in astrocytes and neurons localization of RFC and PCFT (but not FRα) was observed. In microglia, no expression of the folate transporters or receptor was detected. ConclusionsRFC and PCFT localization at the AB may represent a novel route of folate transport into the CSF, with transporter expression in neurons and astrocytes facilitating folate uptake into brain parenchyma cellular targets. Modulating folate transport at these brain compartments may provide a novel strategy in increasing brain folate uptake in disorders associated with defective FRα and impaired brain folate transport at the BCSFB. Funding SourcesThis work is supported by the Natural Sciences and Engineering Research Council of Canada (RB). VS is a recipient of several graduate scholarships.

SCREENING OF PROTON PUMP INHIBITOR ANTAGONIST FOR HUMAN FOLATE TRANSPORTER

Folate transport is crucial for proper proliferation of cells. Amongst humans, the folate is procured from external sources since it is not synthesized in the human body. Hence specific transporters are involved in uptake of folate. For the malignant cancerous cells, these folate are crucially required on very frequent rate to fulfil the rapid proliferation of the cancerous cells. In the present study, we have comparatively studied three antagonist drug molecules which could be a potential candidate to inhibit the folate uptake by the human Proton Coupled folate transporter (hPCFT). These candidate antagonist include Pemetrexed, 2-[(4-Aminobenzoyl)amino] pentanedioate-pABA-Glu and Methotrexate. Out of these three antagonist drug, the Pemetrexed molecule was observed to specifically bind to the key active site loop (G155XXG158) of the hPCFT transporter. The Binding energy of the Pemetrexed was also comparatively lowest (-7.6 kcal/mol). Hence from the present study we conclude that the Pemetrexed antagonist drug is more e fficient to inhibit folate transport as compared to the 2-[(4-Aminobenzoyl)amino]pentanedioate-pABA-Glu and Methotrexate antagonist drug molecules.

Structural basis of antifolate recognition and transport by PCFT.

Folates (also known as vitamin B9) have a critical role in cellular metabolism as the starting point in the synthesis of nucleic acids, amino acids and the universal methylating agent S-adenylsmethionine1,2. Folate deficiency is associated with a number of developmental, immune and neurological disorders3-5. Mammals cannot synthesize folates de novo; several systems have therefore evolved to take up folates from the diet and distribute them within the body3,6. The proton-coupled folate transporter (PCFT) (also known as SLC46A1) mediates folate uptake across the intestinal brush border membrane and the choroid plexus4,7, and is an important route for the delivery of antifolate drugs in cancer chemotherapy8-10. How PCFT recognizes folates or antifolate agents is currently unclear. Here we present cryo-electron microscopy structures of PCFT in a substrate-free state and in complex with a new-generation antifolate drug (pemetrexed). Our results provide a structural basis for understanding antifolate recognition and provide insights into the pH-regulated mechanism of folate transport mediated by PCFT.

Salvia miltiorrhiza (SM) Injection Ameliorates Iron Overload-Associated Cardiac Dysfunction by Regulating the Expression of DMT1, TfR1, and FP1 in Rats.

Previous studies have found that Salvia miltiorrhiza (SM) injection have a protective effect on the iron overloaded (IO) heart. However, the mechanisms are not completely known. In the present study, we investigated the underlying mechanisms based on the iron transport-related proteins. The rats were randomly divided into five groups: control, IO group, low-dose SM group, high-dose SM group, and deferoxamine control group. Iron dextran was injected to establish the IO model. After 14 days of treatment, cardiac histological changes were observed by hematoxylin and eosin (H&E) staining. Iron uptake-related proteins divalent metal transporter-1 (DMT-1), transferrin receptor-1 (TfR-1), and iron export-related proteins ferroportin1 (FP1) in the heart were detected by Western blotting. The results showed that SM injection decreased cardiac iron deposition, ameliorated cardiac function, and inhibited cardiac oxidation. Most important of all, SM injection downregulated the expression of DMT-1 and TfR-1 and upregulated FP1 protein levels compared with the IO group. Our results indicated that reducing cardiac iron uptake and increasing iron excretion may be one of the important mechanisms of SM injection reducing cardiac iron deposition and improving cardiac function under the conditions of IO.

IL-18 Promotes Erythrophagocytosis and Erythrocyte Degradation by M1 Macrophages in a Calcific Microenvironment

BackgroundCalcific aortic-valve disease (CAVD) is the most common cause of aortic valve replacement in developed countries. Intraleaflet hemorrhage has been found to be positively correlated with the progression of CAVD. Although most research has focused on erythrocyte degradation products, which promote progression of CAVD, the process of erythrophagocytosis and erythrocyte degradation by macrophages in intraleaflet hemorrhage areas has remained unexplored. MethodsThe erythrocyte degradation products of aortic valve specimens were detected by Perls’ staining and quantified. The gene and protein expression levels of interleukin (IL)-18 in THP-1–polarized macrophages cultured in osteogenic medium were tested. We also quantified the iron and heme degraded by macrophages and analyzed the expression of ferroportin (FPN) and heme oxygenase-1 (HO-1) in the osteogenic medium. Furthermore, we tested the mRNA and protein levels of osteoblast markers in valve interstitial cells after co-culture with M1 macrophages treated with IL-18 and erythrocytes. ResultsOur experiments demonstrated that IL-18 activates HO-1 and FPN to promote erythrophagocytosis and erythrocyte degradation by macrophages in a calcific microenvironment via p38 and Erk1/2. We also found that the calcific microenvironment promotes IL-18 mRNA and protein expression in THP-1-polarized macrophages. ConclusionsIn conclusion, IL-18 promotes M1 macrophage-mediated erythrophagocytosis and erythrocyte degradation by regulating the activation of HO-1 and FPN via p38 and Erk1/2 in a calcific microenvironment.

Roles of Zinc Transporters That Control the Essentiality and Toxicity of Manganese and Cadmium

Cellular transport systems for both essential and toxic trace elements remain elusive. In our studies on the transport systems for cadmium (Cd), we found that the cellular uptake of Cd is mediated by the transporter for manganese (Mn). We identified ZIP8 and ZIP14, members of the ZIP zinc (Zn) transporter family, as transporters having high affinities for both Cd and Mn. Notably, the uptake of Cd into rice root from soil is mediated by a transporter for Mn as well. We found that ZIP8 is highly expressed at the S3 segment of the kidney proximal tubule and can transport glomerulus-filtered Cd and Mn ions in the lumen into epithelial cells of the proximal tubule, suggesting that ZIP8 has an important role in the renal reabsorption of both toxic Cd and essential Mn. Mutations in ZIP8 and ZIP14 genes were found in humans having congenital disorders associated with the disturbed transport of Mn, although ZIP8 mutation causes whole-body Mn deficiency while ZIP14 mutation causes Mn accumulation in the brain. Mutations in ZnT10, a Zn transporter responsible for Mn excretion, also cause hyperaccumulation of Mn in the brain. Results of genome-wide association studies have indicated that ZIP8 SNPs are involved in a variety of common diseases. Thus, ZIP8, ZIP14, and ZnT10 play crucial roles in the transport of Mn and thereby control Mn- and Cd-related biological events in the body.

On Iron Metabolism and Its Regulation.

Iron is a critical metal for several vital biological processes. Most of the body’s iron is bound to hemoglobin in erythrocytes. Iron from senescent red blood cells is recycled by macrophages in the spleen, liver and bone marrow. Dietary iron is taken up by the divalent metal transporter 1 (DMT1) in enterocytes and transported to portal blood via ferroportin (FPN), where it is bound to transferrin and taken up by hepatocytes, macrophages and bone marrow cells via transferrin receptor 1 (TfR1). While most of the physiologically active iron is bound hemoglobin, the major storage of most iron occurs in the liver in a ferritin-bound fashion. In response to an increased iron load, hepatocytes secrete the peptide hormone hepcidin, which binds to and induces internalization and degradation of the iron transporter FPN, thus controlling the amount of iron released from the cells into the blood. This review summarizes the key mechanisms and players involved in cellular and systemic iron regulation.

Organic iron absorption and expression of related transporters in the small intestine of broilers

An experiment was conducted to investigate the effect of organic and inorganic Fe sources on Fe absorption and expression of related transporters in the small intestine of broilers. Iron-deficient intact broilers (7-day-old) were fed an Fe-unsupplemented corn-soybean meal basal diet or the basal diet supplemented with 60 mg Fe/kg as Fe sulfate (FeSO4•7H2O), Fe-Met with weak chelation strength (Fe-Met W), Fe-proteinate with moderate chelation strength (Fe-Prot M) or Fe-proteinate with extremely strong chelation strength (Fe-Prot ES) for 14 d. The plasma Fe contents were enhanced (P < 0.02) by Fe addition, and greater (P < 0.0002) in Fe-Prot M and Fe-Prot ES groups than in Fe-Met W and FeSO4 groups. Supplemental Fe decreased (P < 0.03) the divalent metal transporter 1 (DMT1) mRNA levels in the duodenum and jejunum, and ferroportin 1 (FPN1) mRNA levels in the duodenum on d 21, but no differences (P > 0.20) were detected among different Fe sources. Regardless of Fe source, the mRNA levels of DMT1 and FPN1 were higher (P < 0.02) in the duodenum than in the jejunum and ileum, and in the jejunum than in the ileum (P < 0.05). However, Fe addition did not affect (P > 0.10) the mRNA levels of amino acid transporters and protein levels of DMT1 and FPN1 in the small intestine of broilers. These results indicate that organic Fe sources with stronger chelation strength showed higher Fe absorption in broilers in vivo; the mRNA expression of Fe and amino acid transporters varied along with the extension of the small intestine; the absorption of Fe as organic Fe chelates was not mediated by the amino acid transporters in intact chicks in this study.

Deubiquitinase USP35 modulates ferroptosis in lung cancer via targeting ferroportin.

BackgroundFerroptosis is essential to regulate tumor growth and serves as a promising therapeutic target to lung cancer. Ubiquitin‐specific protease 35 (USP35) belongs to the deubiquitinases family that is associated with cell proliferation and mitosis. In this research, we aim to elucidate the potential role and molecular basis of USP35 in lung cancer.MethodsLung cancer cells were infected with lentiviral vectors to silence or overexpress USP35. Cell viability, colony formation, lipid reactive oxygen species production, intracellular iron metabolism, and other ferroptotic markers were detected. The role of USP35 on ferroptosis and tumor progression were also tested in mouse tumor xenograft models in vivo.ResultsUSP35 was abundant in human lung cancer tissues and cell lines. USP35 knockdown promoted ferroptosis, and inhibited cell growth, colony formation, and tumor progression in lung cancer cells. USP35 overexpression did not affect tumorigenesis and ferroptosis under basal conditions, but reduced erastin/RSL3‐triggered iron disturbance and ferroptosis, thereby facilitating lung cancer cell growth and tumor progression. Further studies determined that USP35 directly interacted with ferroportin (FPN) and functioned as a deubiquitinase to maintain its protein stability. More importantly, we observed that USP35 knockdown sensitized lung cancer cells to cisplatin and paclitaxel chemotherapy.ConclusionUSP35 modulates ferroptosis in lung cancer via targeting FPN, and it is a promising therapeutic target to lung cancer.