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

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

To prepare a kind of effective non-viral transduction vector, which can deliver exogenous gene into the brain, this vector can be injected through vein system and has the ability to penetrate blood brain barrier. Several groups of materials proportion, type of oil phase, water-oil ratio, phosphatides-cholesterol ratio, temperature of steaming, ultrasonic temperature and time were compared for optimization. Well-constructed immunoliposomes encapsuling LacZ gene were infused into rats through tail vein. 48 h after injection, expression product beta-galactosidase of LacZ gene was detected by histochemistry staining to convince the validity of immunoliposomes as non-viral vectors. The best proportion of synthesis immunoliposomes is as following: phosphatides-cholesterol ratio is 1:1, lipids/drug is 100:1, the type of oil phrase is dichloromethane, oil-water ratio is 4:1, temperature of steaming is 30 degrees C, ultrasonic temperature and time is 10 degrees C and 5 min. At last, 10% trehalose was added as a stabilizer. The entrapment rate is 87.24% and antibody coupling rate is 69%. When immunoliposomes were infused into rats, the expression of LacZ gene could be observed in the brain and periphery organs. Through the best proportion of materials, gene delivering immunoliposomes had been synthesized successfully. This non-viral vector can deliver exogenous gene penetrating blood brain barrier and express in the brain, and will be well-used in the field of gene therapy of cerebral diseases.
Animals ; Antibodies, Monoclonal ; administration & dosage ; pharmacokinetics ; Blood-Brain Barrier ; Brain ; blood supply ; immunology ; metabolism ; Drug Delivery Systems ; methods ; Genetic Vectors ; Lac Operon ; genetics ; Liposomes ; administration & dosage ; immunology ; pharmacokinetics ; Male ; Particle Size ; Plasmids ; Polyethylene Glycols ; administration & dosage ; pharmacokinetics ; Rats ; Receptors, Transferrin ; immunology ; Tissue Distribution ; beta-Galactosidase ; genetics ; metabolism

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

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

Mitochondrial ferritin (MtF), a new player in iron metabolism, first identified in 2001, is highly homologous to ferritin both structurally and functionally. Preliminary studies have suggested that MtF might play very important roles in the regulation of mitochondrial iron homeostasis. Leukemic cells, just like other malignant cells, demand more iron for their greater proliferation potential. However, little is known about what roles MtF might play in leukemic cell iron metabolism and cell proliferation. The aim of this study was to investigate the expression of MtF, transferrin receptor 1 (TfR1) and ferritin (Fn) mRNAs in K562 leukemic cells during TPA-induced cell differentiation and to explore the interrelationship between the expression levels of these iron metabolism-related molecules. K562 cells cultured with or without TPA (16 nmol/L) were collected at 24, 72 and 120 hours respectively. Cell differentiation toward monocyte lineage was confirmed by microscopic study (Wright's staining) and flow cytometry. Semiquantitative RT-PCR was performed to determine mRNA expression, with house-keeping gene beta-actin as control reference. This study revealed that over 95% of K562 cells showed morphological features of monocyte/macrophage, and the expression of CD64 on cell surface increased significantly at day 5 with TPA treatment. K562 cells could express a certain level of MtF before TPA-induced differentiation. With increase of TPA-induced cell differentiation, MtF mRNA expressions were downregulated progressively. After 5 days of induced cell differentiation, expression levels of MtF and TfR1 mRNA were just 50.3% and 68.2% of that before TPA treatment. While Fn mRNA expression increased to 1.97 folds of that before TPA treatment. It is concluded that MtF expression is downregulated during TPA-induced K562 cell differentiation, with concomitant downregulation of TfR1 and upregulation of Fn. The coordinated expression regulation of these key iron metabolism-related molecules during cell differentiation may in turn inhibit TfR1-mediated iron uptake via endocytosis and thus adversely affect cell proliferation potential.
Antigens, CD ; metabolism ; Cell Proliferation ; Cell Transformation, Neoplastic ; drug effects ; Ferritins ; biosynthesis ; genetics ; Humans ; Iron-Regulatory Proteins ; metabolism ; K562 Cells ; Mitochondria ; metabolism ; RNA, Messenger ; biosynthesis ; genetics ; Receptors, Transferrin ; metabolism ; Tetradecanoylphorbol Acetate ; pharmacology

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

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