Hemochromatosis/genetics* ; Histocompatibility Antigens Class I/genetics* ; Humans ; Mutation ; Receptors, Transferrin/genetics*

Iron homeostasis plays an important role for the maintenance of human health. It is known that iron metabolism is tightly regulated by several key genes, including divalent metal transport-1(), transferrin receptor 1(), transferrin receptor 2(), ferroportin(), hepcidin(), hemojuvelin() and . Recently, it is reported that DNA methylation, histone acetylation, and microRNA (miRNA) epigenetically regulated iron homeostasis. Among these epigenetic regulators, DNA hypermethylation of the promoter region of , and bone morphogenetic protein 6 () genes result in inhibitory effect on the expression of these iron-related gene. In addition, histone deacetylase (HADC) suppresses gene expression. On the contrary, HADC inhibitor upregulates gene expression. Additional reports showed that miRNA can also modulate iron absorption, transport, storage and utilization via downregulation of and other genes. It is noteworthy that some key epigenetic regulatory enzymes, such as DNA demethylase TET2 and histone lysine demethylase JmjC KDMs, require iron for the enzymatic activities. In this review, we summarize the recent progress of DNA methylation, histone acetylation and miRNA in regulating iron metabolism and also discuss the future research directions.
Epigenesis, Genetic ; Gene Expression Regulation ; genetics ; Homeostasis ; Humans ; Iron ; metabolism ; Receptors, Transferrin

Human transferrin receptor (TfR) was isolated from homogenates of placental tissues by affinity chromatography on transferrin-Sepharose, and then used to screen human scFv against it from a fully-synthesized phage scFv library. After verifying the specificity, gene fragment of one of the selected scFv was inserted into the plasmid pET22b(+) and transformed into E. coli BL21(DE3) . Expression of scFv in transformant was induced with 0.5mmol/L IPTG. ELISA assay on HeLa cells showed that scFv protein could recognize and bind to TfR on the surface of HeLa cells. The scFv was purified by one-step affinity chromatography with Ni+ -NTA agarose, and injected into Kunming mouse via tail veins. This scFv was detected in brain tissues 1h later by capillary depletion method, which indicates that scFv protein can permeate through the blood brain barrier by mediation of the TfR receptor. Our works lay the foundation for the treatment of tumors and central nervous system diseases.
Animals ; Antibodies, Anti-Idiotypic ; genetics ; isolation & purification ; metabolism ; Escherichia coli ; genetics ; metabolism ; HeLa Cells ; Humans ; Immunoglobulin Fragments ; biosynthesis ; genetics ; immunology ; Immunoglobulin Variable Region ; biosynthesis ; genetics ; immunology ; Mice ; Receptors, Transferrin ; genetics ; immunology ; Recombinant Proteins ; biosynthesis ; genetics ; Transferrin ; metabolism

Extracellular Signal-Regulated MAP Kinases ; metabolism ; Glomerular Mesangium ; immunology ; Glycosylation ; Humans ; Immunoglobulin A ; metabolism ; Phosphorylation ; Receptors, Fc ; analysis ; genetics ; Receptors, Transferrin ; analysis ; genetics

To explore the mechanism of iron metabolism and its regulation as well as the roles of IRP(2) in ion metabolism of HL-60 cells, HL-60 cells were cultured in RPMI 1640 medium supplemented with 10% heat-inactivated fetal bovine serum, which was treated with ferric chloride (FeCl(3)) or deferoxamine (DFO). The cells were harvested at 12, 24 and 48 hours of proliferation, and total RNA was isolated; cDNA was synthesized by reverse transcription (RT), and relative expression levels of IRP(2) mRNA, Fn mRNA and TfR mRNA were determined by RT-PCR. The results showed at follows: (1) the level of IRP(2) mRNA remained constant in all cells, whether or not treated with DFO or FeCl(3). However, the expression of IRP(2) mRNA decreased when the time of cell culture was prolonged. There was no significant difference between groups (F(B-S) = 1.199, P > 0.05), but there was significant difference among the different time culture (F(W-S) = 43.418, P < 0.01). (2) Cells which treated neither with DFO nor ferri chloride showed significant difference from the control (F(W-S) = 7.184, F(B-S) = 113.926; P < 0.01). The level of TfR mRNA increased in the cells treated with DFO. Surprisingly, when cells treated with FeCl(3), there was not decline of TfR mRNA expression, but it increased lightly at 12 hours and peaked at 24 hours and declined drastically at 48 hours. (3) The level of Fn mRNA in the cells treated with FeCl(3) was approximately 2-fold as the control cells. In contrast with the control cells, there was significant difference (P < 0.05). The level of Fn mRNA of the cells treated with DFO had little change. As compared with the control cells, no significant difference was seen (P > 0.05). (4) There was not any significant correlation between IRP(2) mRNA and TfR mRNA or Fn mRNA in HL-60 cells (r = -0.005; r = 0.074; P > 0.05). It is concluded that (1) IRP(2) may regulate the iron metabolism in HL-60 cells by altering amounts of the IRP(2) 3.7- or 6.4-kb mRNA at the transcriptional level, or by IRP(2) degradation at the post transcriptional level. (2) Both of Fn mRNA and TfR mRNA participated, more or less, in the iron metabolism in HL-60 cells.
Ferritins ; genetics ; Gene Expression Regulation, Neoplastic ; HL-60 Cells ; Humans ; Iron Regulatory Protein 2 ; genetics ; RNA, Messenger ; genetics ; metabolism ; Receptors, Transferrin ; genetics ; Reverse Transcriptase Polymerase Chain Reaction

This article reports the effect of dihydroartemisinin (DHA) on transferrin receptor (TfR) in myeloid leukemia cells by establishing the model of normal iron HL60 and K562 cells and iron overload K562 cells in vitro. The TfR content of myeloid leukemia cells was determined by flow cytometry, and the effect of DHA on iron content in K562 cells was determined by atomic absorption spectrophotometric analysis. Furthermore, the inhibitory effect of DHA on the anti-proliferation and expression of TfR protein and mRNA in myeloid leukemia cells was studied. As a result, DHA effectively decreased the TfR content and down-regulated TfR protein expression in normal iron HL60 and K562 cells in a dose- and time-dependent manner and inhibited the cell proliferation. The IC50 were 1.74 and 11.33 micromol x L(-1), respectively. DHA exerted more pronounced inhibitory action on expression of TfR protein and mRNA in iron overload K562 cells. Compared to normal iron K562 cells, the TfR protein and mRNA levels were lowered by 28.1% (P < 0.01) and 26. 2% (P < 0. 05) , respectively, after DHA treatment for 48 h in iron overload K562 cells. Moreover, DHA decreased the iron content of iron overload K562 cells and inhibited the proliferation of iron overload K562 cells more potently. DHA effectively down-regulated the TfR content as well as expression of TfR protein and mRNA in normal iron myeloid leukemia cells. DHA also inhibited the proliferation of HL60 and K562 cells. The anti-proliferation effect of DHA on iron overload K562 cells was more striking.
Antineoplastic Agents, Phytogenic ; administration & dosage ; pharmacology ; Artemisinins ; administration & dosage ; pharmacology ; Cell Proliferation ; drug effects ; Dose-Response Relationship, Drug ; Down-Regulation ; HL-60 Cells ; Humans ; K562 Cells ; RNA, Messenger ; metabolism ; Receptors, Transferrin ; genetics ; metabolism ; Transferrin ; metabolism

OBJECTIVETo investigate the mRNA expression of transferrin receptor 1 (TfR1) and iron regulatory protein 1 (IRP1) in the full-term placenta from different maternal iron status, and explore the mechanism of placental iron transport and regulation.

METHODSThe mRNA level of TfR1 and IRP1 in full-term placentae was detected by reverse transcription polymerase chain reaction (RT-PCR) in normal group (N), iron deficiency group (ID) and iron deficiency anemia group (IDA).

RESULTS(1) The expression of TfR1 mRNA in N group was 0.4813 +/- 0.1891, in ID group was 0. 6647 +/- 0.2788, and in IDA group was 0.9767 +/- 0.2858. There was significant difference between IDA group and N group or ID group (t = 0.002, P < 0.01 or t = 0.028, P < 0.05), and was no difference between ID group and N group (t = 0.117, P > 0.05). (2) The expression of IRP1 mRNA in N group was 0.2616 +/- 0.0785, in ID group was 0.3696 +/- 0.1801, and in IDA group was 0.3971 +/- 0.0902 and was no difference among the three groups (F = 1.845, P = 0.179).

CONCLUSIONSThe expression of TfR1 mRNA is increased when maternal iron deficiency progressed while there is no change in the expression of IRP1 mRNA in the placentae of TfR1 mRNA indicated that IRP1 takes part in the regulation of placenta iron transport.

Anemia, Iron-Deficiency ; genetics ; Antigens, CD ; metabolism ; Female ; Humans ; Iron Regulatory Protein 1 ; metabolism ; Placenta ; metabolism ; Pregnancy ; RNA, Messenger ; metabolism ; Receptors, Transferrin ; metabolism

To obtain single chain variable fragment (scFv) and bivalent single chain variable fragment (bsFv) against transferrin receptor, up-stream and down-stream primers were designed according to the complementary sequences of FR1 region of variable heavy (VH) and FR4 of variable light (VL), respectively, which contained inter-linker G4S and the restriction endonuclease SfiI, AscI and NotI. Two pieces of scFv fragments were first amplified through PCR and then inserted into plasmid pAB1, which could express scFv protein once induced by IPTG in the host bacteria. To express scFv and bsFv, E. coli TG1 was cultured in LB broth and was induced by IPTG. The restriction enzyme digestion map and DNA sequencing demonstrated that scFv and bsFv genes were successfully inserted into the expression plasmid. SDS-PAGE and Western blotting revealed the protein band at 35kD and 60kD, which were consistent with the molecular weight of scFv and bsFv respectively. Flow cytometry showed that scFv and bsFv harbored the specific binding activity with TfR expressed in various tumor cells, and the avidity of bsFv was higher than that of the parent scFv.
Base Sequence ; Cloning, Molecular ; Escherichia coli/genetics ; Escherichia coli/metabolism ; Genetic Vectors/genetics ; Hep G2 Cells ; K562 Cells ; Molecular Sequence Data ; Receptors, Transferrin/*immunology ; Recombinant Fusion Proteins/biosynthesis ; Recombinant Fusion Proteins/genetics ; Single-Chain Antibodies/*biosynthesis ; Single-Chain Antibodies/genetics

OBJECTIVETo explore the effect of T(3) on the expression of transferrin receptor (TfR) and ferritin (Fn) in K562 cells and its possible mechanism.

METHODSFlow cytometry was used for the detection of TfR expression, radioimmunoassay for Fn expression, RNA/protein band shift assay for the binding activity of iron regulatory protein (IRP) and iron responsive elements (IRE), and RT-PCR for TfR and Fn mRNA levels.

RESULTSDifferent concentration of T(3) significantly increased Fn expression of K562 cells, especially at 100 nmol/L and 200 nmol/L (p < 0.05). However, T(3) had no effect on TfR expression. T(3) decreased the binding activity between IRP and IRE, particularly at concentration of 50 nmol/L. Different concentration of T(3) increased Fn-H mRNA level at different time point while it had no effect on TfR mRNA level.

CONCLUSIONT(3) increased Fn expression of K562 cells through the possible mechanisms of either the post-transcriptional regulation or transcriptional modulation.

Ferritins ; biosynthesis ; drug effects ; genetics ; Flow Cytometry ; Gene Expression Regulation, Leukemic ; drug effects ; Humans ; K562 Cells ; RNA, Messenger ; genetics ; Radioimmunoassay ; Receptors, Transferrin ; biosynthesis ; drug effects ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Triiodothyronine ; pharmacology

As an essential metal for sustaining life, iron is involved in a number of metabolic processes, including DNA synthesis, electron transport, oxygen delivery, and so on. Iron metabolism involves the absorption, transport, and use of iron and is strictly regulated. Numerous studies have found a positive correlation between iron storage and the risk of tumors, such as colorectal carcinoma, hepatic cancer, renal carcinoma, lung cancer, and gastric cancer. In tumor cells, iron metabolism changes by several mechanisms, such as regulating the growth of tumor cells by transferrin, accelerating the uptake of iron by the overexpressions of transferrin receptors 1 and 2 (TfR1 and TfR2), synthesizing or secreting ferritin by some malignant tumor cells, and upregulating the level of hepcidin in patients with cancer. Some advances on diagnosis and treatment based on iron metabolism have been achieved, such as increasing the transfection and target efficiency of transferrin-polyethylenimine (PEI), inducing cell apoptosis by beta-guttiferin through interacting with TfR1.
Animals ; Antibiotics, Antineoplastic ; pharmacology ; Antigens, CD ; genetics ; metabolism ; Antimicrobial Cationic Peptides ; biosynthesis ; genetics ; Apoptosis ; Cell Proliferation ; Doxorubicin ; pharmacology ; Ferritins ; metabolism ; physiology ; Hepcidins ; Humans ; Interleukin-18 ; pharmacology ; Iron ; metabolism ; physiology ; Neoplasms ; metabolism ; pathology ; RNA, Messenger ; metabolism ; Receptors, Transferrin ; genetics ; metabolism ; Transferrin ; metabolism ; physiology ; Tumor Suppressor Protein p53 ; pharmacology