scholarly journals Expression of the haemopexin-transport system in cultured mouse hepatoma cells. Links between haemopexin and iron metabolism

1988 ◽  
Vol 256 (3) ◽  
pp. 941-950 ◽  
Author(s):  
A Smith ◽  
B E Ledford
Keyword(s):  
Cell Growth ◽  
Iron Homeostasis ◽  
Iron Status ◽  
Sole Source ◽  
Transport Capacity ◽  
Hepatic Transport ◽  
Type Analysis ◽  
Mouse Hepatoma ◽  
Minimal Deviation ◽  
Triton X

Minimal deviation hepatoma (Hepa) cells, from the mouse hepatoma B7756, synthesize and secrete haemopexin and express both the haemopexin receptor and the membrane haem-binding protein (MHBP) associated with the receptor, making this cell line the first available for detailed study of both haemopexin metabolism and hepatic transport. The 17.5 kDa MHBP was detected in Triton X-100 extracts of Hepa cells by immunoblotting with goat anti-rabbit MHBP. Scatchard-type analysis of haem-125I-haemopexin binding at 4 degrees C revealed 35,000 receptors per cell of high affinity (Kd 17 nM). Haemopexin-mediated haem transport at 37 degrees C is saturable, having an apparent Km of 160 nM and a Vmax. of 7.5 pmol of haem/10(6) cells per h during exponential growth. Haem-transport capacity is highest in the period just before the cells enter their exponential phase of growth and slowest in stationary phase. Interestingly, haem-haemopexin serves as effectively as iron-transferrin as the sole source of iron for cell growth by Hepa cells. Furthermore, depriving Hepa cells of iron by treatment with desferrioxamine (DF) increases the number of cell-surface haemopexin receptors to 65,000 per cell and consequently increases haemopexin-mediated haem transport. The effects of DF do not appear to require protein synthesis since they are not prevented by cycloheximide. Treatment of Hepa cells with hydroxyurea, an inhibitor of the iron-requiring enzyme ribonucleotide reductase that is obligatory for DNA synthesis, enhanced haemopexin-mediated haem transport. Thus, these studies provide the first evidence for regulation of haem transport by the iron status of cells and suggest a linkage between haemopexin, iron homeostasis and cell growth.

scholarly journals CBIO-10. REDUCED IRON EXPORT FUNCTIONS IN A CELL INTRINSIC MANNER TO DRIVE GLIOBLASTOMA GROWTH

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii17-ii17
Author(s):  
Katie Troike ◽  
Erin Mulkearns-Hubert ◽  
Daniel Silver ◽  
James Connor ◽  
Justin Lathia
Keyword(s):  
Tumor Cells ◽  
Iron Uptake ◽  
Iron Homeostasis ◽  
Iron Status ◽  
Tumor Grade ◽  
Hfe Gene ◽  
Iron Release ◽  
Female Patients ◽  
Cellular Iron

Abstract Glioblastoma (GBM), the most common primary malignant brain tumor in adults, is characterized by invasive growth and poor prognosis. Iron is a critical regulator of many cellular processes, and GBM tumor cells have been shown to modulate expression of iron-associated proteins to enhance iron uptake from the surrounding microenvironment, driving tumor initiation and growth. While iron uptake has been the central focus of previous investigations, additional mechanisms of iron regulation, such as compensatory iron efflux, have not been explored in the context of GBM. The hemochromatosis (HFE) gene encodes a transmembrane glycoprotein that aids in iron homeostasis by limiting cellular iron release, resulting in a sequestration phenotype. We find that HFE is upregulated in GBM tumors compared to non-tumor brain and that expression of HFE increases with tumor grade. Furthermore, HFE mRNA expression is associated with significantly reduced survival specifically in female patients with GBM. Based on these findings, we hypothesize that GBM tumor cells upregulate HFE expression to augment cellular iron loading and drive proliferation, ultimately leading to reduced survival of female patients. To test this hypothesis, we generated Hfe knockdown and overexpressing mouse glioma cell lines. We observed significant alterations in the expression of several iron handling genes with Hfe knockdown or overexpression, suggesting global disruption of iron homeostasis. Additionally, we show that knockdown of Hfe in these cells increases apoptosis and leads to a significant impairment of tumor growth in vivo. These findings support the hypothesis that Hfe is a critical regulator of cellular iron status and contributes to tumor aggression. Future work will include further exploration of the mechanisms that contribute to these phenotypes as well as interactions with the tumor microenvironment. Elucidating the mechanisms by which iron effulx contributes to GBM may inform the development of next-generation targeted therapies.

scholarly journals Iron Supplementation Confers Protection on Disease Severity in Dextran Sodium Sulfate (DSS)-Induced Colitis in Rats (OR15-05-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Amanda Bries ◽  
Rachel Derscheid ◽  
Paige Curry ◽  
Joe Webb ◽  
Olivia Meier ◽  
...  
Keyword(s):  
Disease Activity ◽  
Iron Supplementation ◽  
Iron Homeostasis ◽  
Iron Status ◽  
Fold Increase ◽  
Deficiency Anemia ◽  
State University ◽  
Sprague Dawley ◽  
Beneficial Effects ◽  
Funding Sources

Abstract Objectives Koji iron, enriched with FeSO4 (Ultimine®; ULT), is a novel source of supplemental iron. Previously, we reported ULT had similar absorption as ferrous sulfate (FeSO4), while resulting in less reported adverse effects in women. Iron deficiency anemia is a common manifestation of inflammatory bowel disease (IBD) due to malabsorption and gastrointestinal (GI) bleeding. Therefore, the objective of our study was to identify the efficacy of 2 forms of iron supplementation on impaired GI integrity and anemia caused by dextran sulfate sodium (DSS)-induced colitis. Methods Six wk old Sprague Dawley rats (n = 40) were randomly assigned to one of four treatment groups (n = 10/group): 1) Control with no DSS; 2) Control + DSS only (Nfe); 3) DSS + ULT; 4) DSS + FeSO4. Animals were maintained on the AIN-93 G diets for 7 d. Colitis was induced by administering fresh 3.5% (w/v) DSS ad lib throughout the study. Daily iron supplementation (6 mg Fe/kg BW) was provided in a pulverized treat, and disease activity indices were observed (gross bleeding, stool consistency and weight loss). Histological scoring of colonic ulcerations, inflammation and grade were assessed. Iron status indicators and liver hepcidin were detected using ELISA and qRT-PCR, respectively. Results The severity score of IBD was significantly higher in the animals without iron supplementation than those treated with iron (P < 0.0001). Moreover, iron supplementation protected against diminished hemoglobin and hematocrit levels as a result of DSS treatment (P = 0.001 and P = 0.03, respectively); whereas, these parameters were not significantly (NS) different between ULT and FeSO4. Improvement was found with post mortem disease score of DSS-induced rats with ULT compared to FeSO4 and Nfe by 14% and 39%, respectively (NS). Compared to healthy controls, FeSO4 resulted in a 3.5-fold increase in liver hepcidin gene expression, whereas ULT caused no change. Conclusions The results of this study highlight the beneficial effects iron supplementation has on the disease activity evoked by severe GI inflammation. Furthermore, this data suggests ULT attenuates the progression of IBD by supporting iron homeostasis. Additional analyses will explore the possible mechanisms of these results by identifying the systemic inflammation. Funding Sources College of Human Sciences, Iowa State University Collaborative Seed Grant Program.

scholarly journals Hepcidin: A Critical Regulator of Iron Metabolism during Hypoxia

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Korry J. Hintze ◽  
James P. McClung
Keyword(s):  
Iron Metabolism ◽  
Iron Homeostasis ◽  
Molecular Mechanisms ◽  
Iron Absorption ◽  
Iron Acquisition ◽  
Iron Status ◽  
Hypoxia Inducible Factor ◽  
Hypoxia Response Element ◽  
Hypoxia Response ◽  
Hepcidin Expression

Iron status affects cognitive and physical performance in humans. Recent evidence indicates that iron balance is a tightly regulated process affected by a series of factors other than diet, to include hypoxia. Hypoxia has profound effects on iron absorption and results in increased iron acquisition and erythropoiesis when humans move from sea level to altitude. The effects of hypoxia on iron balance have been attributed to hepcidin, a central regulator of iron homeostasis. This paper will focus on the molecular mechanisms by which hypoxia affects hepcidin expression, to include a review of the hypoxia inducible factor (HIF)/hypoxia response element (HRE) system, as well as recent evidence indicating that localized adipose hypoxia due to obesity may affect hepcidin signaling and organismal iron metabolism.

Serum Prohepcidin and Iron Homeostasis in Patients with Breast Cancer

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 5291-5291
Author(s):  
Janet G. Grudeva ◽  
Ivanka Slavejnova Nenova ◽  
Dora Dimitrova Terzieva ◽  
Maria Ivanova Spasova ◽  
Nikolay Petrov Boyadjiev
Keyword(s):  
Breast Cancer ◽  
Iron Homeostasis ◽  
Conflicts Of Interest ◽  
Iron Status ◽  
Transferrin Saturation ◽  
University Hospital ◽  
Direct Result ◽  
Full Blood Count ◽  
Normocytic Anemia ◽  
Cytotoxic Treatment

Abstract Abstract 5291 Introduction: Cancer-related anemia (CRA) has multifactorial etiology and complex pathogenesis. It is defined as normochromic, normocytic anemia with reticulocyto-penia and hypoferremia. Hepcidin is recognized as the central factor in causing CRA. Objective: To investigate the changes in the serum levels of prohepcidin (pHp) and markers of iron homeostasis for gathering more data on the pathogenesis of CRA. Patients and Methods: The authors analyzed prospectively 46 newly diagnosed women with breast cancer, aged 29–72 years (average 47.5±9.0 SD), who had the same clinical stage, histology and hormonal status. They were diagnosed and treated in the Clinic of Oncology and Hematology - University Hospital for a 2-year period (2009–2010). Serum pHp levels and common markers of iron status including serum iron (sFe), transferrin saturation, soluble tranferrin receptor (sTfR), Zn-protoporphyrin (ZPP), ferritin as well as vitamin B12 and folate were measured before treatment initiation and two months afterwards. Serum pHp was determined by a competitive immunotest. All statistical data was computed by the methods of variational and correlation analyses. Results and Discussion: For the two-month follow up interval parameters of full blood count remained without statistically significant deviation. Although the analyzed parameters in the first and second blood samples remained within the reference intervals, the decrease of pHp and the changes of iron-containing substances and ZPP in red blood cells cannot be neglected. However the correlation coefficient (R) between decreased pHp, increased sFe (R=0.314), sTfR (R=0.258), ZPP (R=0.118) and decreased ferritin (R=0.099), were low instead of the expected higher relationship. The obtained results do not support the idea that iron increase and other changes of iron homeostasis in these patients is a direct result of regulatory decrease of pHp. The two-month interval is likely short enough to rule out a potential direct suppressive effect of the specific cytotoxic treatment, and therefore we do not discuss such potential influence on iron homeostasis. Conclusion: Iron homeostasis dysregulation is one of CRA components. In its complex pathogenesis several other factors interfere e.g. such related to the disease; therapy related factors; altered erythropoietin production; activation of cytokines (IL-6 is the major promoter of hepcidin production). Disclosures: No relevant conflicts of interest to declare.

scholarly journals Serum prohepcidin concentration: no association with iron absorption in healthy men; and no relationship with iron status in men carrying HFE mutations, hereditary haemochromatosis patients undergoing phlebotomy treatment, or pregnant women

2007 ◽  
Vol 97 (3) ◽  
pp. 544-549 ◽  
Author(s):  
Mark A. Roe ◽  
Caroline Spinks ◽  
Anne-Louise M. Heath ◽  
Linda J. Harvey ◽  
Rob Foxall ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Iron Homeostasis ◽  
Iron Absorption ◽  
Iron Status ◽  
Red Cell ◽  
Wild Type ◽  
Hereditary Haemochromatosis ◽  
Healthy Men ◽  
Hfe Mutations ◽  
Potential Use

Hepcidin plays a major role in iron homeostasis, but understanding its role has been hampered by the absence of analytical methods for quantification in blood. A commercial ELISA has been developed for serum prohepcidin, a hepcidin precursor, and there is interest in its potential use in the clinical and research arena. We investigated the association between serum prohepcidin concentration and iron absorption in healthy men, and its relationship with iron status in men carrying HFE mutations, hereditary haemochromatosis patients, and pregnant women. Iron absorption was determined in thirty healthy men (fifteen wild-type, fifteen C282Y heterozygote) using the stable isotope red cell incorporation technique. Iron status was measured in 138 healthy men (ninety-one wild-type, forty-seven C282Y heterozygote), six hereditary haemochromatosis patients, and thirteen pregnant women. Mean serum prohepcidin concentrations were 214 (sd 118) ng/ml [208 (sd 122) ng/ml in wild-type and 225 (sd 109) ng/ml in C282Y heterozygotes] in healthy men, 177 (sd 36) ng/ml in haemochromatosis patients, and 159 (sd 59) ng/ml in pregnant women. There was no relationship between serum prohepcidin concentration and serum ferritin in any subject groups, nor was it associated with efficiency of iron absorption. Serum prohepcidin is not a useful biomarker for clinical or research purposes.

scholarly journals Rescue of cell growth by sphingosine with disruption of lipid microdomain formation in Saccharomyces cerevisiae deficient in sphingolipid biosynthesis

2006 ◽  
Vol 394 (1) ◽  
pp. 237-242 ◽  
Author(s):  
Motohiro Tani ◽  
Akio Kihara ◽  
Yasuyuki Igarashi
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Growth ◽  
Serine Palmitoyltransferase ◽  
Kinase Gene ◽  
Yeast Saccharomyces Cerevisiae ◽  
Long Chain Base ◽  
Triton X ◽  
Lipid Microdomain ◽  
Sphingolipid Biosynthesis ◽  
Complex Sphingolipids

In the yeast Saccharomyces cerevisiae, sphingolipids are essential for cell growth. Inactivation of sphingolipid biosynthesis, such as by disrupting the serine palmitoyltransferase gene (LCB2), is lethal, but cells can be rescued by supplying an exogenous LCB (long-chain base) like PHS (phytosphingosine) or DHS (dihydrosphingosine). In the present study, supplying SPH (sphingosine), an unnatural LCB for yeast, similarly rescued the Δlcb2 cells, but only when SPH 1-phosphate production was inhibited by deleting the LCB kinase gene LCB4. Exogenously added SPH was adequately converted into phosphoinositol-containing complex sphingolipids. Interestingly, cells carrying SPH-based sphingolipids exhibited a defect in the association of Pma1p with Triton X-100-insoluble membrane fractions, and displayed sensitivities to both Ca2+ and hygromycin B. These results suggest that the SPH-based sphingolipids in these cells have properties that differ from those of the PHS- or DHS-based sphingolipids in regard to lipid microdomain formation, leading to abnormal sensitivities towards certain environmental stresses. The present paper is the first report showing that in sphingolipid-deficient S. cerevisiae, the requirement for LCB can be fulfilled by exogenous SPH, although this supplement results in failure of lipid microdomain formation.

Inhibition of tumor cell growth by triton X-100 through specific effects on cell-cycle-regulatory components

2004 ◽  
Vol 11 (1) ◽  
pp. 95-103 ◽  
Author(s):  
Esther R. Picache ◽  
Loubna Hassanieh ◽  
Daniel Broek ◽  
Axel H. Schönthal
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Tumor Cell ◽  
Tumor Cell Growth ◽  
Specific Effects ◽  
Triton X

scholarly journals Regulatory Mechanisms for Iron Homeostasis Are Present in Small Preterm Newborns

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2460-2460
Author(s):  
Carina Levin ◽  
Marina Marina Peniakov ◽  
Dan Reich ◽  
Scott Weiner ◽  
Jamal Hasnein ◽  
...  
Keyword(s):  
Birth Weight ◽  
Blood Transfusion ◽  
Preterm Infants ◽  
Iron Supplementation ◽  
Iron Homeostasis ◽  
Reticulocyte Count ◽  
Iron Status ◽  
Transferrin Saturation ◽  
Regulatory Mechanisms ◽  
Vlbw Infants

Abstract Iron, an essential micronutrient, plays an important role in cellular functions. To prevent deficiency, iron supplementation is universally recommended for preterm infants; nevertheless, assessment of newborn iron stores is not currently recommended. Both iron deficiency and iron excess early in life can have adverse effects on neurodevelopment and outcomes, and therefore sensitive and specific methods for evaluating iron status and determining optimal iron supplementation are essential. The current study aimed to evaluate iron status and iron-supplementation efficacy/toxicity in preterm infants using new laboratory methods, and to correlate iron status with clinical, nutritional, laboratory and therapeutic factors, and the amount of blood extracted and transfused. We evaluated 50 very low birth weight (VLBW) preterm infants treated under standard protocols at the Emek Medical Center NICU, 26 (54%) male. Iron supplementation was administered enterally from 4 wk of age (4 mg elemental iron/kg body weight daily). Laboratory studies included CBC, reticulocyte count, reticulocyte hemoglobin (Hb) content, iron, transferrin, transferrin saturation, ferritin, erythropoietin, hepcidin, CRP and non-transferrin-bound iron (NTBI) (Aferrix, Israel). Samples were obtained at 3 different times during hospitalization: (-0) before starting oral iron supplementation, (-1) on d 4-7 of supplementation, and (-2) after at least 2 wk of supplementation. To better understand iron metabolism, the analyzed preterm population was divided into subgroups for comparison: infants who did not require blood transfusion (No-BT) vs. those who received one or more transfusions (BT); infants who did not show abnormal NTBI levels (≤0.19 μmol/L; No-NTBI) vs. those with abnormal NTBI levels (≥ 0.2 μmol/L in one or more samples; NTBI). Mean birth weight of the studied infants was 1264.5 ± 342 g, gestational age 29.1 ± 2.5 wk, age at hospital discharge 57.6 ± 20 d and weight at discharge, 2412 ± 421 g. The BT group included 35 (70%) infants. The mean birth weight was lower in the BT vs. No-BT group (1199 ± 351 g vs. 1416±273 g, P = 0.04). Mean red blood cell, Hb, and hematocrit were higher in the BT vs. No-BT group. Conversely, mean platelet count, reticulocyte count, and erythropoietin were higher in the No-BT vs. BT group, suggesting an erythropoietic response to lower Hb levels and utilization of iron through effective erythropoiesis. In the BT group, mean serum iron, ferritin, transferrin saturation and hepcidin were higher, whereas transferrin was lower than in the No-BT group. This reflects increased iron burden induced by the transfusions, making NTBI more likely to develop with potential toxicity. Regarding NTBI, 34 (68%) of the infants were in the No-NTBI group, and 16 (32%) showed increased NTBI levels. The Δiron (sum of iron from diet, supplementation and transfusion minus iron output via blood extractions) before starting supplementation was significantly higher in the NTBI vs. No-NTBI group. Mean transferrin saturation at -0 was higher, whereas transferrin at -2 was lower in the NTBI vs. No-NTBI group, demonstrating a higher iron burden in NTBI infants. The odds of developing NTBI rose 7.2% for each percent increment in transferrin saturation at -0 (O.R. 1.072, 95% CI, 1.005-1.143, P = 0.036), and a cutoff of 26% at -0 gave 80% sensitivity and 41% specificity for the presence of NTBI (AUC 0.68). Thus VLBW infants show evidence of regulatory mechanisms for iron homeostasis and iron utilization for erythropoiesis; however, the protective responses are not developed enough to limit the appearance of circulating free iron with potential toxic effects. Neither adverse effects nor presence of NTBI were associated with enteral iron supplementation. Premature infants who received blood transfusions had a positive iron balance, higher Hb and ferritin levels, and reduced erythropoiesis. Consequently, these babies are more likely to develop free iron. Conventional biomarkers are effective for evaluating iron status in VLBW infants. Transferrin saturation seems to be the most reliable and "physiological" biomarker, and a potential predictor of abnormal NTBI levels. These findings support an individualized approach to iron supplementation based on the characteristics of the specific preterm infant while taking into consideration past need for blood transfusion and the infant's iron status. Disclosures No relevant conflicts of interest to declare.

Altered lipid metabolism in Hfe-knockout mice promotes severe NAFLD and early fibrosis

2011 ◽  
Vol 301 (5) ◽  
pp. G865-G876 ◽  
Author(s):  
Terrence C. H. Tan ◽  
Darrell H. G. Crawford ◽  
Lesley A. Jaskowski ◽  
Therese M. Murphy ◽  
Mandy L. Heritage ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Knockout Mice ◽  
Iron Homeostasis ◽  
Iron Status ◽  
Current Evidence ◽  
Hepatic Iron ◽  
Potential Contribution ◽  
Nonalcoholic Fatty Liver ◽  
Hepcidin Expression ◽  
Mitochondrial Fatty Acid

The HFE protein plays a crucial role in the control of cellular iron homeostasis. Steatosis is commonly observed in HFE-related iron-overload disorders, and current evidence suggests a causal link between iron and steatosis. Here, we investigated the potential contribution of HFE mutations to hepatic lipid metabolism and its role in the pathogenesis of nonalcoholic fatty liver disease. Wild-type (WT) and Hfe knockout mice ( Hfe−/−) were fed either standard chow, a monounsaturated low fat, or a high-fat, high-carbohydrate diet (HFD) and assessed for liver injury, body iron status, and markers of lipid metabolism. Despite hepatic iron concentrations and body weights similar to WT controls, Hfe −/− mice fed the HFD developed severe hypoxia-related steatohepatitis, Tnf-α activation, and mitochondrial respiratory complex and antioxidant dysfunction with early fibrogenesis. These features were associated with an upregulation in the expression of genes involved in intracellular lipid synthesis and trafficking, while transcripts for mitochondrial fatty acid β-oxidation and adiponectin signaling-related genes were significantly attenuated. In contrast, HFD-fed WT mice developed bland steatosis only, with no inflammation or fibrosis and no upregulation of lipogenesis-related genes. A HFD led to reduced hepatic iron in Hfe −/− mice compared with chow-fed mice, despite higher serum iron, decreased hepcidin expression, and increased duodenal ferroportin mRNA . In conclusion, our results demonstrate that Hfe −/− mice show defective hepatic-intestinal iron and lipid signaling, which predispose them toward diet-induced hepatic lipotoxicity, accompanied by an accelerated progression of injury to fibrosis.

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