Regulation of transferrin receptor 2 protein levels by transferrin

Blood ◽  
2004 ◽  
Vol 104 (13) ◽  
pp. 4294-4299 ◽  
Author(s):  
Aeisha Robb ◽  
Marianne Wessling-Resnick
Keyword(s):  
Transferrin Receptor ◽  
Iron Status ◽  
Critical Role ◽  
Iron Loading ◽  
Liver Iron ◽  
High Iron ◽  
Protein Levels ◽  
Iron Deficient ◽  
Transferrin Receptor 2

Abstract Transferrin receptor 2 (TfR2) plays a critical role in iron homeostasis because patients carrying disabling mutations in the TFR2 gene suffer from hemochromatosis. In this study, iron-responsive regulation of TfR2 at the protein level was examined in vitro and in vivo. HepG2 cell TfR2 protein levels were up-regulated after exposure to holotransferrin (holoTf) in a time- and dose-responsive manner. ApoTf or high-iron treatment with non–Tf-bound iron failed to elicit similar effects, suggesting that TfR2 regulation reflects interactions of the iron-bound ligand. Hepatic TfR2 protein levels also reflected an adaptive response to changing iron status in vivo. Liver TfR2 protein levels were down- and up-regulated in rats fed an iron-deficient and a high-iron diet, respectively. TfR2 was also up-regulated in Hfe-/- mice, an animal model that displays liver iron loading. In contrast, TfR2 levels were reduced in hypotransferrinemic mice despite liver iron overload, supporting the idea that regulation of the receptor is dependent on Tf. This idea is confirmed by up-regulation of TfR2 in β-thalassemic mice, which, like hypotransferrinemic mice, are anemic and incur iron loading, but have functional Tf. Based on these combined results, we hypothesize that TfR2 acts as a sensor of iron status such that receptor levels reflect Tf saturation.

Fetal iron status regulates maternal iron metabolism during pregnancy in the rat

2009 ◽  
Vol 296 (4) ◽  
pp. R1063-R1070 ◽  
Author(s):  
Lorraine Gambling ◽  
Alicja Czopek ◽  
Henriette S. Andersen ◽  
Grietje Holtrop ◽  
S. Kaila S. Srai ◽  
...  
Keyword(s):  
Iron Deficiency ◽  
Iron Metabolism ◽  
Transferrin Receptor ◽  
Iron Status ◽  
Expression Patterns ◽  
Control Group ◽  
Deficient Diet ◽  
Liver Iron ◽  
Iron Supply ◽  
Iron Deficient

Iron metabolism during pregnancy is biased toward maintaining the fetal supply, even at the cost of anemia in the mother. The mechanisms regulating this are not well understood. Here, we examine iron deficiency and supplementation on the hierarchy of iron supply and the gene expression of proteins that regulate iron metabolism in the rat. Dams were fed iron-deficient diets for 4 wk, mated, and either continued on the deficient diet or an iron-supplemented diet during either the first half or the second half of their pregnancy. A control group was maintained on normal iron throughout. They were killed at 0.5, 12.5, or 21.5 days of gestation, and tissues and blood samples were collected. Deficiency and supplementation had differential effects on maternal and fetal hematocrit and liver iron levels. From early in pregnancy, a hierarchy of iron supply is established benefiting the fetus to the detriment of the mother. Transferrin receptor, transferrin receptor 2, and hepcidin mRNA expression were regulated by both iron deficiency and supplementation. Expression patterns showed both organ and supplementation protocol dependence. Further analysis indicated that iron levels in the fetal, and not maternal, liver regulate the expression of liver transferrin receptor and hepcidin expression in the mother.

Effect of hepcidin on intestinal iron absorption in mice

Blood ◽  
2004 ◽  
Vol 103 (10) ◽  
pp. 3940-3944 ◽  
Author(s):  
Abas H. Laftah ◽  
Bala Ramesh ◽  
Robert J. Simpson ◽  
Nita Solanky ◽  
Seiamak Bahram ◽  
...  
Keyword(s):  
Iron Uptake ◽  
Iron Absorption ◽  
Iron Status ◽  
Hfe Gene ◽  
Chain Reaction ◽  
Liver Iron ◽  
Hepcidin Expression ◽  
Iron Deficient ◽  
Polymerase Chain

Abstract The effect of the putative iron regulatory peptide hepcidin on iron absorption was investigated in mice. Hepcidin peptide was synthesized and injected into mice for up to 3 days, and in vivo iron absorption was measured with tied-off segments of duodenum. Liver hepcidin expression was measured by reverse transcriptase–polymerase chain reaction. Hepcidin significantly reduced mucosal iron uptake and transfer to the carcass at doses of at least 10 μg/mouse per day, the reduction in transfer to the carcass being proportional to the reduction in iron uptake. Synthetic hepcidin injections down-regulated endogenous liver hepcidin expression excluding the possibility that synthetic hepcidin was functioning by a secondary induction of endogenous hepcidin. The effect of hepcidin was significant at least 24 hours after injection of hepcidin. Liver iron stores and hemoglobin levels were unaffected by hepcidin injection. Similar effects of hepcidin on iron absorption were seen in iron-deficient and Hfe knockout mice. Hepcidin inhibited the uptake step of duodenal iron absorption but did not affect the proportion of iron transferred to the circulation. The effect was independent of iron status of mice and did not require Hfe gene product. The data support a key role for hepcidin in the regulation of intestinal iron uptake.

The Natural Flavonoid Naringenin Inhibits the Cell Growth of WilmsTumorinChildren by Suppressing TLR4/NF-κB Signaling

2020 ◽  
Vol 20 ◽  
Author(s):  
Hongtao Li ◽  
Peng Chen ◽  
Lei Chen ◽  
Xinning Wang
Keyword(s):  
Cell Growth ◽  
Western Blot ◽  
Wilms Tumor ◽  
Critical Role ◽  
Time Dependent ◽  
Luciferase Assay ◽  
Dependent Manner ◽  
Tlr4 Expression ◽  
Protein Levels

Background: Nuclear factor kappa B (NF-κB) is usually activated in Wilms tumor (WT) cells and plays a critical role in WT development. Objective: The study purpose was to screen a NF-κB inhibitor from natural product library and explore its effects on WT development. Methods: Luciferase assay was employed to assess the effects of natural chemical son NF-κB activity. CCK-8 assay was conducted to assess cell growth in response to naringenin. WT xenograft model was established to analyze the effect of naringenin in vivo. Quantitative real-time PCR and Western blot were performed to examine the mRNA and protein levels of relative genes, respectively. Results: Naringenin displayed significant inhibitory effect on NF-κB activation in SK-NEP-1 cells. In SK-NEP-1 and G-401 cells, naringenin inhibited p65 phosphorylation. Moreover, naringenin suppressed TNF-α-induced p65 phosphorylation in WT cells. Naringenin inhibited TLR4 expression at both mRNA and protein levels in WT cells. CCK-8 staining showed that naringenin inhibited cell growth of the two above WT cells in dose-and time-dependent manner, whereas Toll-like receptor 4 (TLR4) over expression partially reversed the above phenomena. Besides, naringenin suppressed WT tumor growth in dose-and time-dependent manner in vivo. Western blot found that naringenin inhibited TLR4 expression and p65 phosphorylation in WT xenograft tumors. Conclusion: Naringenin inhibits WT development viasuppressing TLR4/NF-κB signaling

The influence of high-altitude living on body iron

Blood ◽  
2005 ◽  
Vol 106 (4) ◽  
pp. 1441-1446 ◽  
Author(s):  
James D. Cook ◽  
Erick Boy ◽  
Carol Flowers ◽  
Maria del Carmen Daroca
Keyword(s):  
Standard Error ◽  
Transferrin Receptor ◽  
Quantitative Assessment ◽  
Iron Status ◽  
Dietary Iron ◽  
Body Iron ◽  
Iron Stores ◽  
Iron Deficient ◽  
Iron Based ◽  
Maternal Iron

Abstract The quantitative assessment of body iron based on measurements of the serum ferritin and transferrin receptor was used to examine iron status in 800 Bolivian mothers and one of their children younger than 5 years. The survey included populations living at altitudes between 156 to 3750 m. Body iron stores in the mothers averaged 3.88 ± 4.31 mg/kg (mean ± 1 SD) and 1.72 ± 4.53 mg/kg in children. No consistent effect of altitude on body iron was detected in children but body iron stores of 2.77 ± 0.70 mg/kg (mean ± 2 standard error [SE]) in women living above 3000 m was reduced by one-third compared with women living at lower altitudes (P < .001). One half of the children younger than 2 years were iron deficient, but iron stores then increased linearly to approach values in their mothers by 4 years of age. When body iron in mothers was compared with that of their children, a striking correlation was observed over the entire spectrum of maternal iron status (r = 0.61, P < .001). This finding could provide the strongest evidence to date of the importance of dietary iron as a determinant of iron status in vulnerable segments of a population. (Blood. 2005;106:1441-1446)

scholarly journals Role of Cathepsin S in Periodontal Inflammation and Infection

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
S. Memmert ◽  
A. Damanaki ◽  
A. V. B. Nogueira ◽  
S. Eick ◽  
M. Nokhbehsaim ◽  
...  
Keyword(s):  
Periodontal Diseases ◽  
Interleukin 1 ◽  
Critical Role ◽  
Gingival Tissue ◽  
Cathepsin S ◽  
Protein Levels ◽  
Periodontal Inflammation

Cathepsin S is a cysteine protease and regulator of autophagy with possible involvement in periodontitis. The objective of this study was to investigate whether cathepsin S is involved in the pathogenesis of periodontal diseases. Human periodontal fibroblasts were cultured under inflammatory and infectious conditions elicited by interleukin-1β and Fusobacterium nucleatum, respectively. An array-based approach was used to analyze differential expression of autophagy-associated genes. Cathepsin S was upregulated most strongly and thus further studied in vitro at gene and protein levels. In vivo, gingival tissue biopsies from rats with ligature-induced periodontitis and from periodontitis patients were also analyzed at transcriptional and protein levels. Multiple gene expression changes due to interleukin-1β and F. nucleatum were observed in vitro. Both stimulants caused a significant cathepsin S upregulation. A significantly elevated cathepsin S expression in gingival biopsies from rats with experimental periodontitis was found in vivo, as compared to that from control. Gingival biopsies from periodontitis patients showed a significantly higher cathepsin S expression than those from healthy gingiva. Our findings provide original evidence that cathepsin S is increased in periodontal cells and tissues under inflammatory and infectious conditions, suggesting a critical role of this autophagy-associated molecule in the pathogenesis of periodontitis.

scholarly journals Large G protein α-subunit XLαs limits clathrin-mediated endocytosis and regulates tissue iron levels in vivo

2017 ◽  
Vol 114 (45) ◽  
pp. E9559-E9568 ◽  
Author(s):  
Qing He ◽  
Richard Bouley ◽  
Zun Liu ◽  
Marc N. Wein ◽  
Yan Zhu ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
G Protein ◽  
Critical Role ◽  
Hek293 Cells ◽  
Activity Levels ◽  
Α Subunit ◽  
Proteomic Screen ◽  
Protein Levels ◽  
G Protein Α Subunit

Alterations in the activity/levels of the extralarge G protein α-subunit (XLαs) are implicated in various human disorders, such as perinatal growth retardation. Encoded by GNAS, XLαs is partly identical to the α-subunit of the stimulatory G protein (Gsα), but the cellular actions of XLαs remain poorly defined. Following an initial proteomic screen, we identified sorting nexin-9 (SNX9) and dynamins, key components of clathrin-mediated endocytosis, as binding partners of XLαs. Overexpression of XLαs in HEK293 cells inhibited internalization of transferrin, a process that depends on clathrin-mediated endocytosis, while its ablation by CRISPR/Cas9 in an osteocyte-like cell line (Ocy454) enhanced it. Similarly, primary cardiomyocytes derived from XLαs knockout (XLKO) pups showed enhanced transferrin internalization. Early postnatal XLKO mice showed a significantly higher degree of cardiac iron uptake than wild-type littermates following iron dextran injection. In XLKO neonates, iron and ferritin levels were elevated in heart and skeletal muscle, where XLαs is normally expressed abundantly. XLKO heart and skeletal muscle, as well as XLKO Ocy454 cells, showed elevated SNX9 protein levels, and siRNA-mediated knockdown of SNX9 in XLKO Ocy454 cells prevented enhanced transferrin internalization. In transfected cells, XLαs also inhibited internalization of the parathyroid hormone and type 2 vasopressin receptors. Internalization of transferrin and these G protein-coupled receptors was also inhibited in cells expressing an XLαs mutant missing the Gα portion, but not Gsα or an N-terminally truncated XLαs mutant unable to interact with SNX9 or dynamin. Thus, XLαs restricts clathrin-mediated endocytosis and plays a critical role in iron/transferrin uptake in vivo.

scholarly journals Variability of the Transferrin Receptor 2 Gene in AMD

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Daniel Wysokinski ◽  
Janusz Blasiak ◽  
Mariola Dorecka ◽  
Marta Kowalska ◽  
Jacek Robaszkiewicz ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Risk Factors ◽  
Transferrin Receptor ◽  
Fenton Reaction ◽  
Iron Homeostasis ◽  
Critical Role ◽  
Age Related Macular Degeneration ◽  
Age Related ◽  
Its Gene ◽  
Transferrin Receptor 2

Oxidative stress is a major factor in the pathogenesis of age-related macular degeneration (AMD). Iron may catalyze the Fenton reaction resulting in overproduction of reactive oxygen species. Transferrin receptor 2 plays a critical role in iron homeostasis and variability in its gene may influence oxidative stress and AMD occurrence. To verify this hypothesis we assessed the association between polymorphisms of theTFR2gene and AMD. A total of 493 AMD patients and 171 matched controls were genotyped for the two polymorphisms of theTFR2gene: c.1892C>T (rs2075674) and c.−258+123T>C (rs4434553). We also assessed the modulation of some AMD risk factors by these polymorphisms. The CC and TT genotypes of the c.1892C>T were associated with AMD occurrence but the latter only in obese patients. The other polymorphism was not associated with AMD occurrence, but the CC genotype was correlated with an increasing AMD frequency in subjects withBMI<26. The TT genotype and the T allele of this polymorphism decreased AMD occurrence in subjects above 72 years, whereas the TC genotype and the C allele increased occurrence of AMD in this group. The c.1892C>T and c.−258+123T>C polymorphisms of theTRF2gene may be associated with AMD occurrence, either directly or by modulation of risk factors.

scholarly journals Astrocyte-specific deletion of the transcription factor Yin Yang 1 in murine substantia nigra mitigates manganese-induced dopaminergic neurotoxicity

2020 ◽  
Vol 295 (46) ◽  
pp. 15662-15676 ◽  
Author(s):  
Edward Pajarillo ◽  
James Johnson ◽  
Asha Rizor ◽  
Ivan Nyarko-Danquah ◽  
Getinet Adinew ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Substantia Nigra ◽  
Critical Role ◽  
Conditional Knockout ◽  
Motor Functions ◽  
Mn Toxicity ◽  
Protein Levels ◽  
Yin Yang 1 ◽  
Yin Yang

Manganese (Mn)-induced neurotoxicity resembles Parkinson's disease (PD), but the mechanisms underpinning its effects remain unknown. Mn dysregulates astrocytic glutamate transporters, GLT-1 and GLAST, and dopaminergic function, including tyrosine hydroxylase (TH). Our previous in vitro studies have shown that Mn repressed GLAST and GLT-1 via activation of transcription factor Yin Yang 1 (YY1). Here, we investigated if in vivo astrocytic YY1 deletion mitigates Mn-induced dopaminergic neurotoxicity, attenuating Mn-induced reduction in GLAST/GLT-1 expression in murine substantia nigra (SN). AAV5-GFAP-Cre-GFP particles were infused into the SN of 8-week–old YY1flox/flox mice to generate a region-specific astrocytic YY1 conditional knockout (cKO) mouse model. 3 weeks after adeno-associated viral (AAV) infusion, mice were exposed to 330 μg of Mn (MnCl2 30 mg/kg, intranasal instillation, daily) for 3 weeks. After Mn exposure, motor functions were determined in open-field and rotarod tests, followed by Western blotting, quantitative PCR, and immunohistochemistry to assess YY1, TH, GLAST, and GLT-1 levels. Infusion of AAV5-GFAP-Cre-GFP vectors into the SN resulted in region-specific astrocytic YY1 deletion and attenuation of Mn-induced impairment of motor functions, reduction of TH-expressing cells in SN, and TH mRNA/protein levels in midbrain/striatum. Astrocytic YY1 deletion also attenuated the Mn-induced decrease in GLAST/GLT-1 mRNA/protein levels in midbrain. Moreover, YY1 deletion abrogated its interaction with histone deacetylases in astrocytes. These results indicate that astrocytic YY1 plays a critical role in Mn-induced neurotoxicity in vivo, at least in part, by reducing astrocytic GLAST/GLT-1. Thus, YY1 might be a potential target for treatment of Mn toxicity and other neurological disorders associated with dysregulation of GLAST/GLT-1.

scholarly journals The Iron Status of Sickle Cell Anaemia Patients in Ilorin, North Central Nigeria

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Musa A. Sani ◽  
James O. Adewuyi ◽  
Abiola S. Babatunde ◽  
Hannah O. Olawumi ◽  
Rasaki O. Shittu
Keyword(s):  
Sickle Cell ◽  
Serum Ferritin ◽  
Transferrin Receptor ◽  
Sickle Cell Anaemia ◽  
Iron Status ◽  
Serum Transferrin ◽  
Cross Sectional ◽  
Serum Transferrin Receptor ◽  
Iron Deficient ◽  
The Mean

Objectives. Sickle cell anaemia (SCA) is one of the commonest genetic disorders in the world. It is characterized by anaemia, periodic attacks of thrombotic pain, and chronic systemic organ damage. Recent studies have suggested that individuals with SCA especially from developing countries are more likely to be iron deficient rather than have iron overload. The study aims to determine the iron status of SCA patients in Ilorin, Nigeria.Methods. A cross-sectional study of 45 SCA patients in steady state and 45 non-SCA controls was undertaken. FBC, blood film, sFC, sTfR, and sTfR/log sFC index were done on all subjects.Results. The mean patients’ serum ferritin (589.33 ± 427.61 ng/mL) was significantly higher than the mean serum ferritin of the controls (184.53 ± 119.74 ng/mL). The mean serum transferrin receptor of the patients (4.24 ± 0.17 μg/mL) was higher than that of the controls (3.96 ± 0.17 μg/mL) (p=0.290). The mean serum transferrin receptor (sTfR)/log serum ferritin index of the patients (1.65 ± 0.27 μg/mL) was significantly lower than that of the control (1.82 ± 0.18 μg/mL) (p=0.031).Conclusion. Iron deficiency is uncommon in SCA patients and periodic monitoring of the haematological, biochemical, and clinical features for iron status in SCA patients is advised.

Serum Soluble Transferrin Receptor in Heterozygous β-Thalassaemia: Application in the Diagnosis of Iron Deficiency and as Hematologic Marker of Erythroid Activity According to Thalassaemic Genotypes (β0 vs β+).

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3828-3828
Author(s):  
Jose Manuel Calvo-Villas ◽  
María Francisca Zapata ◽  
Ivan Alvarez ◽  
Silvia de la Iglesia ◽  
Jorge Cuesta ◽  
...  
Keyword(s):  
Iron Deficiency ◽  
Transferrin Receptor ◽  
Biochemical Parameters ◽  
Iron Status ◽  
Direct Sequencing ◽  
Saturation Index ◽  
Transferrin Saturation ◽  
Soluble Transferrin Receptor ◽  
Iron Deficient ◽  
Significant Difference

Abstract Although an increased level of serum soluble transferrin receptor (sTfR) have been found in both heterozygous β-thalassaemia patients with iron deficiency and in those with more severe genotype (β0), it is not a useful marker of iron deficiency status associated to β-thalassaemia. The aim of this study was to analyse the use of two biochemical parameters (sTfR and sTfR/log of ferritin ratio) to determine the iron status and to evaluate the degree of erythropoietic activity in a group of 221 β-thalassaemic heterozigotes patients (155 β0 and 66 β+). Serum ferritin and transferrin saturation index were measured in order to establish the iron status. Of the whole group, 51 patients were iron defficient (βthal-ID) while the remaining 170 were iron sufficient (βthal-IS). Based on the combination of β-thalassaemia genotype and iron status, patients were classified into four subgroups: β0thalassaemia and iron-sufficient (β0thal-IS) (n=124); β0thalassaemia and iron-deficient (β0thal-ID) (n=31); β+thalassaemia and iron-sufficient (β+thal-IS) (n=46); β+thalassaemia and iron-deficient (β+thal-ID) (n=20). 258 healthy and 56 iron-deficient individuals were used as controls. All the haematological parameters were measured by using analyzer Coulter® GEN-S™. Haemoglobins A2 (Hb A2) and F (HbF) were analysed by high performance liquid chromatography and molecular analysis was performed by real-time PCR and direct sequencing techniques. Chemical, inmunoturbidimetrical and nephelometric methods were used to measure iron status as well as sTfR. Comparison of haemalogical and biochemical parameters between subgroups was performed by using the t-student test and correlation analysis was calculated by using least-squares regression model. Mean sTfR level obtained was 2.63 ± 0.8 mg/dL and 2.57 ± 1.1 mg/dL in βthal-ID and βthal-IS patients respectively (p=0.783). Soluble transferrin receptor showed a positive correlation with HbA2, HbF and reticulocyte count values in βthal-IS patients (r=0.208 [p<0.05], r=0.440 [p<0.0001] and r=0.393 [p<0.00001] respectively) while it did not reach a significant correlation in βthal-ID patients. Mean sTfR/log sFt ratio was 2.75 ± 1.6 and 1.34 ± 0.5 in βthal-ID and βthal-IS patients (p<0.001). Interestingly, sTfR level was significantly higher in β0thal-IS patients when compared with β+thal-IS patients (2.76 ± 0.9 vs 1.42 ± 0.4) (p<0.001) as a result of an increased globin chains imbalance related to the β0 genotype. In the other hand, in the comparison between β0thal-ID and β+thal-ID subgroups neither sTfr level (2.71 ± 0.7 vs 2.40 ± 1.1) (p=0.417) nor sTfR/log sFt ratio (2.93 ± 1.7 vs 2.24 ± 1.3) (p=0.371) showed significant difference. In summary, sTfR/log sFt ratio is a valid parameter for diagnosis of iron deficiency associated to heterozygous β-thalassaemia. Unlike the findings observed in β-thalassaemic heterozigotes with normal iron status, sTfR level is not useful to evaluate the genotype severity in those with iron deficiency. Consequently, iron status should be determined before using sTfR as a parameter to provide a reliable estimation of the ineffective erythropoiesis related to the severity of β-thalassaemia genotypes.

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