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Journal of Controlled Release :... May 2023Transferrin receptor (TfR)-mediated transcytosis is an attractive pathway for delivering large-molecule therapeutics to the central nervous system across the blood-brain...
Transferrin receptor (TfR)-mediated transcytosis is an attractive pathway for delivering large-molecule therapeutics to the central nervous system across the blood-brain barrier. Despite the clinical success of some drugs conjugated with TfR-binder, the desired drug profile for efficient TfR-mediated delivery to the targeted compartment within the brain, especially considering the species-related differences, has not been fully elucidated. To provide a prospective direction in the TfR-mediated drug delivery system, we developed an advanced physiologically based pharmacokinetic (PBPK) model. The model addresses TfR-mediated trans- and intracellular disposition of anti-TfR antibodies from brain capillary blood, endothelial cells, extracellular fluid (ECF), and eventually to brain parenchymal cells (BPCs), which correspond to pharmacological target sites of interest. The PBPK model is applicable in rats, monkeys, and human TfR knock-in (hTfR-KI) mice with satisfactory prediction accuracy through model calibration using the brain and plasma PK data of anti-TfR monoclonal antibodies, including their fused protein, with diverse binding affinity to TfR (TfR-K). The sensitivity analysis to determine drug properties required for the optimal brain delivery revealed 1) a bell-shaped relationship between TfR-K and brain exposure; 2) a minimum species difference between monkeys and hTfR-KI mice in the optimal TfR-K range, but not with rats; 3) a low TfR-K range to be preferably targeted for BPCs compared with ECF; and 4) an increase in brain exposure when using the pH-sensitive antibody. This may advance model-informed drug development, improve molecular design optimization, and provide precise human dose projection of drugs leveraging TfR-mediated shuttle technology into the brain.
Topics: Rats; Mice; Humans; Animals; Endothelial Cells; Prospective Studies; Brain; Blood-Brain Barrier; Receptors, Transferrin; Drug Delivery Systems; Transferrin
PubMed: 37031741
DOI: 10.1016/j.jconrel.2023.04.012 -
Therapeutic Delivery May 2013The potential use of many promising novel drugs is limited by their inability to specifically reach their site of action after intravenous administration, without... (Review)
Review
The potential use of many promising novel drugs is limited by their inability to specifically reach their site of action after intravenous administration, without secondary effects on healthy tissues. In order to remediate this problem, the protein transferrin (Tf) has been extensively studied as a targeting molecule for the transport of drug and gene delivery systems to the brain and cancer cells. A wide range of delivery approaches have been developed to target the Tf receptor and they have already improved the specific delivery of Tf-bearing therapeutic agents to their site of action. This review provides a summary of the numerous delivery strategies used to target the Tf receptor and focuses on recent therapeutic advances.
Topics: Animals; Brain; Drug Delivery Systems; Gene Transfer Techniques; Humans; Neoplasms; Receptors, Transferrin; Transferrin
PubMed: 23647279
DOI: 10.4155/tde.13.21 -
The Journal of Biological Chemistry 2021Birt-Hogg-Dubé (BHD) syndrome is a multiorgan disorder caused by inactivation of the folliculin (FLCN) protein. Previously, we identified FLCN as a binding protein of...
Birt-Hogg-Dubé (BHD) syndrome is a multiorgan disorder caused by inactivation of the folliculin (FLCN) protein. Previously, we identified FLCN as a binding protein of Rab11A, a key regulator of the endocytic recycling pathway. This finding implies that the abnormal localization of specific proteins whose transport requires the FLCN-Rab11A complex may contribute to BHD. Here, we used human kidney-derived HEK293 cells as a model, and we report that FLCN promotes the binding of Rab11A with transferrin receptor 1 (TfR1), which is required for iron uptake through continuous trafficking between the cell surface and the cytoplasm. Loss of FLCN attenuated the Rab11A-TfR1 interaction, resulting in delayed recycling transport of TfR1. This delay caused an iron deficiency condition that induced hypoxia-inducible factor (HIF) activity, which was reversed by iron supplementation. In a Drosophila model of BHD syndrome, we further demonstrated that the phenotype of BHD mutant larvae was substantially rescued by an iron-rich diet. These findings reveal a conserved function of FLCN in iron metabolism and may help to elucidate the mechanisms driving BHD syndrome.
Topics: Animals; Antigens, CD; Birt-Hogg-Dube Syndrome; Cytoplasm; Drosophila Proteins; Drosophila melanogaster; HEK293 Cells; Homeostasis; Humans; Iron; Models, Animal; Proto-Oncogene Proteins; Receptors, Transferrin; Tumor Suppressor Proteins; rab GTP-Binding Proteins
PubMed: 33609526
DOI: 10.1016/j.jbc.2021.100426 -
Immunotherapy Sep 2016
Topics: Animals; Antibodies; Antibody-Dependent Cell Cytotoxicity; Antigens, CD; Antigens, Neoplasm; Cell Proliferation; Clinical Trials as Topic; Humans; Immunotherapy; Immunotoxins; Iron; Neoplasms; Receptors, Transferrin
PubMed: 27373880
DOI: 10.2217/imt-2016-0050 -
Acta Biochimica Polonica 2015The aim of the present study was to investigate the association of age related macular degeneration (AMD) risk with some aspects of iron homeostasis: iron concentration...
The aim of the present study was to investigate the association of age related macular degeneration (AMD) risk with some aspects of iron homeostasis: iron concentration in serum, level of soluble transferrin receptor (sTfR), and transferrin receptor (TFRC) genetic variability. Four hundred and ninety one AMD patients and 171 controls were enrolled in the study. Restriction fragment length polymorphism PCR was employed to genotype polymorphisms of the TFRC gene, and colorimetric assays were used to determine the level of iron and sTfR. Multiple logistic regression was applied for all genotype/allele-related analyses and the ANOVA test for iron and sTfR serum level comparison. We found that the genotypes and alleles of the c.-253G > A polymorphism of the TFRC gene were associated with AMD risk and this association was modulated by smoking status, AMD family history, living environment (rural/urban), body mass index and age. The levels of sTfR was higher in AMD patients than controls, whereas concentrations of iron did not differ in these two groups. No association was found between AMD occurrence and the p.Gly142Ser polymorphism of the TRFC gene. The results obtained suggest that transferrin receptor and variability of its gene may influence AMD risk.
Topics: Aged; Analysis of Variance; Antigens, CD; Body Mass Index; Case-Control Studies; Female; Gene Frequency; Genetic Predisposition to Disease; Humans; Iron; Macular Degeneration; Male; Polymorphism, Genetic; Polymorphism, Restriction Fragment Length; Polymorphism, Single Nucleotide; Receptors, Transferrin
PubMed: 25915522
DOI: 10.18388/abp.2014_843 -
Nature Microbiology Dec 2019To maintain prolonged infection of mammals, African trypanosomes have evolved remarkable surface coats and a system of antigenic variation. Within these coats are...
To maintain prolonged infection of mammals, African trypanosomes have evolved remarkable surface coats and a system of antigenic variation. Within these coats are receptors for macromolecular nutrients such as transferrin. These must be accessible to their ligands but must not confer susceptibility to immunoglobulin-mediated attack. Trypanosomes have a wide host range and their receptors must also bind ligands from diverse species. To understand how these requirements are achieved, in the context of transferrin uptake, we determined the structure of a Trypanosoma brucei transferrin receptor in complex with human transferrin, showing how this heterodimeric receptor presents a large asymmetric ligand-binding platform. The trypanosome genome contains a family of around 14 transferrin receptors, which has been proposed to allow binding to transferrin from different mammalian hosts. However, we find that a single receptor can bind transferrin from a broad range of mammals, indicating that receptor variation is unlikely to be necessary for promiscuity of host infection. In contrast, polymorphic sites and N-linked glycans are preferentially found in exposed positions on the receptor surface, not contacting transferrin, suggesting that transferrin receptor diversification is driven by a need for antigenic variation in the receptor to prolong survival in a host.
Topics: Antigenic Variation; Genetic Variation; Host-Parasite Interactions; Humans; Immune Evasion; Ligands; Models, Molecular; Protein Binding; Protein Structure, Tertiary; Protozoan Proteins; Receptors, Transferrin; Transferrin; Trypanosoma brucei brucei; Trypanosomiasis, African
PubMed: 31636418
DOI: 10.1038/s41564-019-0589-0 -
International Journal of Molecular... Mar 2023Nitric oxide (NO) is a gasotransmitter that avidly binds both free and heme-bound iron, forming relatively stable iron nitrosyl compounds (FeNOs). We have previously...
Nitric oxide (NO) is a gasotransmitter that avidly binds both free and heme-bound iron, forming relatively stable iron nitrosyl compounds (FeNOs). We have previously demonstrated that FeNOs are present in the human placenta and are elevated in preeclampsia and intrauterine growth restriction. The ability of NO to sequester iron raises the possibility of the NO-mediated disruption of iron homeostasis in the placenta. In this work, we tested whether exposure of placental syncytiotrophoblasts or villous tissue explants to sub-cytotoxic concentrations of NO would elicit the formation of FeNOs. Furthermore, we measured changes in the mRNA and protein expression levels of key iron regulatory genes in response to NO exposure. Ozone-based chemiluminescence was used to measure concentrations of NO and its metabolites. Our results showed a significant increase in FeNO levels in placental cells and explants treated with NO ( < 0.0001). The mRNA and protein levels of HO-1 were significantly increased in both cultured syncytiotrophoblasts and villous tissue explants ( < 0.01), and the mRNA levels of hepcidin and transferrin receptor were significantly increased in culture syncytiotrophoblasts and villous tissue explants, respectively, ( < 0.01), while no changes were seen in the expression levels of divalent metal transporter-1 or ferroportin. These results suggest a potential role for NO in iron homeostasis in the human placenta and could be relevant for disorders of pregnancy such as fetal growth restriction and preeclampsia.
Topics: Pregnancy; Female; Humans; Placenta; Heme Oxygenase-1; Transferrin; Hepcidins; Nitric Oxide; Pre-Eclampsia; Receptors, Transferrin; Iron; RNA, Messenger
PubMed: 36982960
DOI: 10.3390/ijms24065887 -
PloS One 2021The blood-brain barrier (BBB) is formed by brain capillary endothelial cells (BECs) supported by pericytes and astrocytes. The BBB maintains homeostasis and protects the...
The blood-brain barrier (BBB) is formed by brain capillary endothelial cells (BECs) supported by pericytes and astrocytes. The BBB maintains homeostasis and protects the brain against toxic substances circulating in the blood, meaning that only a few drugs can pass the BBB. Thus, for drug screening, understanding cell interactions, and pathology, in vitro BBB models have been developed using BECs from various animal sources. When comparing models of different species, differences exist especially in regards to the transendothelial electrical resistance (TEER). Thus, we compared primary mice, rat, and porcine BECs (mBECs, rBECs, and pBECs) cultured in mono- and co-culture with astrocytes, to identify species-dependent differences that could explain the variations in TEER and aid to the selection of models for future BBB studies. The BBB models based on primary mBECs, rBECs, and pBECs were evaluated and compared in regards to major BBB characteristics. The barrier integrity was evaluated by the expression of tight junction proteins and measurements of TEER and apparent permeability (Papp). Additionally, the cell size, the functionality of the P-glycoprotein (P-gp) efflux transporter, and the expression of the transferrin receptor were evaluated and compared. Expression and organization of tight junction proteins were in all three species influenced by co-culturing, supporting the findings, that TEER increases after co-culturing with astrocytes. All models had functional polarised P-gp efflux transporters and expressed the transferrin receptor. The most interesting discovery was that even though the pBECs had higher TEER than rBECs and mBECs, the Papp did not show the same variation between species, which could be explained by a significantly larger cell size of pBECs. In conclusion, our results imply that the choice of species for a given BBB study should be defined from its purpose, instead of aiming to reach the highest TEER, as the models studied here revealed similar BBB properties.
Topics: ATP Binding Cassette Transporter, Subfamily B; Animals; Astrocytes; Blood-Brain Barrier; Cell Culture Techniques; Cell Size; Cells, Cultured; Endothelial Cells; Mice; Models, Biological; Permeability; Rats; Receptors, Transferrin; Swine; Tight Junction Proteins
PubMed: 33711041
DOI: 10.1371/journal.pone.0236770 -
Proteins Mar 2021Machupo virus, known to cause hemorrhagic fevers, enters human cells via binding with its envelope glycoprotein to transferrin receptor 1 (TfR). Similarly, the receptor...
Machupo virus, known to cause hemorrhagic fevers, enters human cells via binding with its envelope glycoprotein to transferrin receptor 1 (TfR). Similarly, the receptor interactions have been explored in biotechnological applications as a molecular system to ferry therapeutics across the cellular membranes and through the impenetrable blood-brain barrier that effectively blocks any such delivery into the brain. Study of the experimental structure of Machupo virus glycoprotein 1 (MGP1) in complex with TfR and glycoprotein sequence homology has identified some residues at the interface that influence binding. There are, however, no studies that have attempted to optimize the binding potential between MGP1 and TfR. In pursuits for finding therapeutic solutions for the New World arenaviruses, and to gain a greater understanding of MGP1 interactions with TfR, it is crucial to understand the structure-sequence relationship driving the interface formation. By displaying MGP1 on yeast surface we have examined the contributions of individual residues to the binding of solubilized ectodomain of TfR. We identified MGP1 binding hot spot residues, assessed the importance of posttranslational N-glycan modifications, and used a selection with random mutagenesis for affinity maturation. We show that the optimized MGP1 variants can bind more strongly to TfR than the native MGP1, and there is an MGP1 sequence that retains binding in the absence of glycosylation, but with the addition of further amino acid substitutions. The engineered variants can be used to probe cellular internalization or the blood-brain barrier crossing to achieve greater understanding of TfR mediated internalization.
Topics: Antigens, CD; Arenaviruses, New World; Humans; Models, Molecular; Mutation; Protein Engineering; Receptors, Transferrin; Viral Envelope Proteins
PubMed: 33068039
DOI: 10.1002/prot.26016 -
Advanced Drug Delivery Reviews Jul 2013Highly proliferative cells have a dramatically increased need for iron which results in the expression of an increased number of transferrin receptors (TFR). This... (Review)
Review
Highly proliferative cells have a dramatically increased need for iron which results in the expression of an increased number of transferrin receptors (TFR). This insight makes the transferrin receptor on these cells an excellent candidate for targeted therapeutics. In this regard, it is critical to understand at a molecular level exactly how the TFR interacts with its ligand, hTF. Understanding of the hTF/TFR pathway could, in theory, maximize the use of this system for development of more effective small molecules or toxin-conjugates to specifically target cancer cells. Many strategies have been attempted with the objective of utilizing the hTF/TFR system to deliver drugs; these include conjugation of a toxin or drug to hTF or direct targeting of the TFR by antibodies. To date, in spite of all of the effort, there is a conspicuous absence of any successful candidate drugs reaching the clinic. We suggest that a lack of quantitative data to determine the basic biochemical properties of the drug carrier and the effects of drug-conjugation on the hTF-TFR interaction may have contributed to the failure to realize the full potential of this system. This review provides some guidelines for developing a more quantitative approach for evaluation of current and future hTF-drug conjugates.
Topics: Animals; Antineoplastic Agents; Drug Carriers; Humans; Receptors, Transferrin; Transferrin
PubMed: 23183585
DOI: 10.1016/j.addr.2012.11.001