Structural, functional, and tissue distribution analysis of human transferrin receptor-2 by murine monoclonal antibodies and a polyclonal antiserum.

Abstract

Human transferrin receptor-2 (TFR-2) is a protein highly homologous to TFR-1/CD71 and is endowed with the ability to bind transferrin (TF) with low affinity. High levels of TFR-2 mRNA were found in the liver and in erythroid precursors. Mutations affecting the TFR-2 gene led to hemochromatosis type 3, a form of inherited iron overload. Several issues on distribution and function of the receptor were answered by raising a panel of 9 monoclonal antibodies specific for TFR-2 by immunizing mice with murine fibroblasts transfected with the human TFR-2 cDNA. A polyclonal antiserum was also produced in mice immunized with 3 peptides derived from the TFR-2 sequence, exploiting an innovative technique. The specificity of all the reagents produced was confirmed by reactivity with TFR-2(+) target cells and simultaneous negativity with TFR-1(+) cells. Western blot analyses showed a dominant chain of approximately 90 kDa in TFR-2 transfectants and HepG2 cell line. Analysis of distribution in normal tissues and in representative cell lines revealed that TFR-2 displays a restricted expression pattern--it is present at high levels in hepatocytes and in the epithelial cells of the small intestine, including the duodenal crypts. Exposure of human TFR-2(+) cells to TF-bound iron is followed by a significant up-regulation and relocalization of membrane TFR-2. The tissue distribution pattern, the behavior following exposure to iron-loaded TF, and the features of the disease resulting from TFR-2 inactivation support the hypothesis that TFR-2 contributes to body iron sensing.

• Authors: Silvia Deaglio, Andrea Capobianco, Angelita Calì, Francesca Bellora, Federica Alberti, Luisella Righi, Anna Sapino, Clara Camaschella, Fabio Malavasi
• Journal: Blood (Blood) Vol. 100 Issue 10 Pg. 3782-9 (Nov 15 2002) ISSN: 0006-4971 [Print] United States
• PMID: 12393650 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antibodies, Monoclonal
• Immune Sera
• Receptors, Transferrin
• TFR2 protein, human
• TFR2 protein, mouse
• Transferrin

Topics

• Animals
• Antibodies, Monoclonal (biosynthesis, immunology)
• Antibody Specificity
• Endothelium (chemistry)
• Hepatocytes (chemistry)
• Humans
• Immune Sera (immunology)
• Immunohistochemistry
• Intestines (cytology)
• Mice
• Mice, Inbred BALB C
• Receptors, Transferrin (immunology, metabolism)
• Tissue Distribution
• Transferrin (pharmacology)
• Tumor Cells, Cultured
• Up-Regulation (drug effects)