[en] BACKGROUND AND OBJECTIVES: Transferrin receptor (TfR) expression in erythroid cells is regulated by a number of factors, including iron status and erythropoietin (Epo) stimulation. However, the impact of these factors on reticulocyte TfR expression in vivo has never been studied. A soluble form of TfR (sTfR) is present in serum in proportion to the mass of cellular TfR. Although sTfR shedding by reticulocytes and erythroblasts has been demonstrated in vitro, the contribution of reticulocyte TfR to serum sTfR has never been evaluated in vivo. DESIGN AND METHODS: We measured directly the total number of reticulocyte TfR in normal rats of different age and iron status, as well as in animals experiencing various conditions and treatments aimed at altering erythropoietic activity and iron status, including rHuEpo therapy, hemolytic anemia, phlebotomies, hypertransfusions, thiamphenicol-induced red cell aplasia or inflammation. In addition, we examined the impact of repeated hypertransfusions with normal, reticulocyte-poor and reticulocyte-rich blood on serum sTfR levels. RESULTS: The number of TfR molecules per reticulocyte was around 50,000 in young rats but was around 100,000 in older animals. These values remained constant in most conditions and in particular were not influenced by iron supplementation or iron overload. However, functional iron deficiency as well as rHuEpo therapy resulted in increased reticulocyte TfR expression. In addition, TfR numbers in reticulocytes were elevated in the early phase of recovery after acute hemolysis or red cell aplasia but normalized soon after. Hypertransfusion experiments clearly demonstrated that reticulocytes can contribute substantially to sTfR levels in vivo. INTERPRETATION AND CONCLUSIONS: TfR numbers are regulated in vivo by the same factors as in vitro, in particular iron deficiency and erythropoietin stimulation. Circulating reticulocytes contribute significantly to serum sTfR levels.
Disciplines :
Hematology
Author, co-author :
R'Zik, Samir ; Centre Hospitalier Universitaire de Liège - CHU > PLAN COS
Loo, Martine
Beguin, Yves ; Centre Hospitalier Universitaire de Liège - CHU > Hématologie clinique
Language :
English
Title :
Reticulocyte transferrin receptor (TfR) expression and contribution to soluble TfR levels.
Ponka P., Lok C.N. (1999) The transferrin receptor: Role in health and disease. Int J Biochem Cell Biol 31:1111-1137.
Lok C.N., Loh T.T. (1998) Regulation of transferrin function and expression: Review and update. Biol Signals Recept 7:157-178.
Huebers H.A., Finch C.A. (1987) The physiology of transferrin and transferrin receptors. Physiol Rev 67:520-582.
Loken M.R., Shah V.O., Dattilio K.L., Civin C.I. (1987) Flow cytometric analysis of human bone marrow: I. Normal erythroid development. Blood 69:255-263.
Sieff C., Bicknell D., Caine G., Robinson J., Lam G., Greaves M.F. (1982) Changes in cell surface antigen expression during hemopoietic differentiation. Blood 60:703-713.
Lesley J., Hyman R., Schulte R. (1984) Expression of transferrin receptor on murine hematopoietic progenitors. Cell Immunol 83:14-25.
Iacopetta B.J., Morgan E.H., Yeoh G.C. (1982) Transferrin receptors and iron uptake during erythroid cell development. Biochim Biophys Acta 687:204-210.
Van Bockxmeer F.M., Morgan E.H. (1979) Transferrin receptors during rabbit reticulocyte maturation. Biochim Biophys Acta 584:76-83.
Haile D.J. (1999) Regulation of genes of iron metabolism by the iron-response proteins. Am J Med Sci 318:230-240.
Hentze M.W., Kuhn L.C. (1996) Molecular control of vertebrate iron metabolism: mRNA-based regulatory circuits operated by iron, nitric oxide, and oxidative stress. Proc Natl Acad Sci USA 93:8175-8182.
Weiss G., Houston T., Kastner S., Johrer K., Grunewald K., Brock J.H. (1997) Regulation of cellular iron metabolism by erythropoietin: Activation of iron-regulatory protein and upregulation of transferrin receptor expression in erythroid cells. Blood 89:680-687.
Tacchini L., Bianchi L., Bernelli-Zazzera A., Cairo G. (1999) Transferrin receptor induction by hypoxia. HIF-1-mediated transcriptional activation and cell-specific post-transcriptional regulation. J Biol Chem 274:24142-24146.
Lok C.N., Ponka P. (1999) Identification of a hypoxia response element in the transferrin receptor gene. J Biol Chem 274:24147-24152.
Beguin Y., Huebers H.A., Josephson B., Finch C.A. (1988) Transferrin receptors in rat plasma. Proc Natl Acad Sci USA 85:637-640.
Huebers H.A., Beguin Y., Pootrakul P., Einspahr D., Finch C.A. (1990) Intact transferrin receptors in human plasma and their relation to erythropoiesis. Blood 75:102-107.
Shih Y.J., Baynes R.D., Hudson B.G., Flowers C.H., Skikne B.S., Cook J.D. (1990) Serum transferrin receptor is a truncated form of tissue receptor. J Biol Chem 265:19077-19081.
Skikne B.S., Flowers C.H., Cook J.D. (1990) Serum transferrin receptor: A quantitative measure of tissue iron deficiency. Blood 75:1870-1876.
Suominen P., Punnonen K., Rajamaki A., Irjala K. (1998) Serum transferrin receptor and transferrin receptor-ferritin index identify healthy subjects with subclinical iron deficits. Blood 92:2934-2939.
Chitambar C.R., Zivkovic Z. (1989) Release of soluble transferrin receptor from the surface of human leukemic HL60 cells. Blood 74:602-608.
Ahn J., Johnstone R.M. (1993) Origin of a soluble truncated transferrin receptor. Blood 81:2442-2451.
Chitambar C.R., Loebel A.L., Noble N.A. (1991) Shedding of transferrin receptor from rat reticulocytes during maturation in vitro: Soluble transferrin receptor is derived from receptor shed in vesicles. Blood 78:2444-2450.
Shintani N., Kohgo Y., Kato J. (1994) Expression and extracellular release of transferrin receptors during peripheral erythroid progenitor cell differentiation in liquid culture. Blood 83:1209-1215.
Cazzola M., Huebers H.A., Sayers M.H., MacPhail A.P., Eng M., Finch C.A. (1985) Transferrin saturation, plasma iron turnover, and transferrin uptake in normal humans. Blood 66:935-939.
Cazzola M., Pootrakul P., Huebers H.A., Eng M., Eschbach J., Finch C.A. (1987) Erythroid marrow function in anemic patients. Blood 69:296-301.
Hershko C., Cook J.D., Finch C.A. (1972) Storage iron kinetics. II. The uptake of hemoglobin iron by hepatic parenchymal cells. J Lab Clin Med 80:624-634.
Lee L.G., Chen C.H., Chiu L.A. (1986) Thiazole orange: A new dye for reticulocyte analysis. Cytometry 7:508-517.
Beguin Y., Clemons G.K., Pootrakul P., Fillet G. (1993) Quantitative assessment of erythropoiesis and functional classification of anemia based on measurements of serum transferrin receptor and erythropoietin. Blood 81:1067-1076.
(1990) Revised recommendations for the measurements of the serum iron in human blood. Iron Panel of the International Committee for Standardization in Haematology. Br J Haematol 75:615-616.
Frazier J.L., Caskey J.H., Yoffe M., Seligman P.A. (1982) Studies of the transferrin receptor on both human reticulocytes and nucleated human cells in culture: Comparison of factors regulating receptor density. J Clin Invest 69:853-865.
Qian Z.M., Morgan E.H. (1992) Changes in the uptake of transferrin-free and transferrin-bound iron during reticulocyte maturation in vivo and in vitro. Biochim Biophys Acta 1135:35-43.
Kohno H., Tokunaga R. (1985) Transferrin and iron uptake by rat reticulocytes. J Biochem (Tokyo) 97:1181-1188.
Black C., Glass J., Nunez M.T., Robinson S.H. (1979) Transferrin binding and iron transport in iron-deficient and iron-replete rats reticulocytes. J Lab Clin Med 93:645-651.
Intragumtornchai T., Huebers H.A., Eng M., Finch C.A. (1988) In vivo transferrin-iron receptor relationships in erythron of rats. Am J Physiol 255.
Shumak K.H., Rachkewich R.A. (1984) Transferrin receptors on human reticulocytes: Variation in site number in haematologic disorders. Am J Hematol 16:23-32.
Garrick M.D., Gniecko K., Liu Y., Cohan D.S., Garrick L.M. (1993) Transferrin and the transferrin cycle in Belgrade rat reticulocytes. J Biol Chem 268:14867-14874.
Allen J., Backstrom K.R., Cooper J.A. (1998) Measurement of soluble transferrin receptor in serum of healthy adults. Clin Chem 44:35-39.
Choi J.W., Pal S.H., Im M.W., Kim S.K. (1999) Change in transferrin receptor concentrations with age. Clin Chem 45:1562-1563.
Atkins M.B., Kappler K., Mier J.W., Isaacs R.E., Berkman E.M. (1995) Interleukin-6-associated anemia: Determination of the underlying mechanism. Blood 86:1288-1291.
Nieken J., Mulder N.H., Buter J. (1995) Recombinant human interleukin-6 induces a rapid and reversible anemia in cancer patients. Blood 86:900-905.
Baynes R.D., Shih Y.J., Hudson B.G., Cook J.D. (1991) Characterization of transferrin receptor released by K562 erythro-leukemia cells. Proc Soc Exp Biol Med 197:416-423.
Johnstone R.M., Bianchini A., Teng K. (1989) Reticulocyte maturation and exosome release: Transferrin receptor containing exosomes shows multiple plasma membrane functions. Blood 74:1844-1851.
Johnstone R.M. (1992) The Jeanne Manery-Fisher Memorial Lecture 1991. Maturation of reticulocytes: Formation of exosomes as a mechanism for shedding membrane proteins. Biochem Cell Biol 70:179-190.
Vidal M., Mangeat P., Hoekstra D. (1997) Aggregation reroutes molecules from a recycling to a vesicle-mediated secretion pathway during reticulocyte maturation. J Cell Sci 110:1867-1877.
Shih Y.J., Baynes R.D., Hudson B.G., Cook J.D. (1993) Characterization and quantitation of the circulating forms of serum transferrin receptor using domain-specific antibodies. Blood 81:234-238.
Baynes R.D., Shih Y.J., Cook J.D. (1994) Mechanism of production of the serum transferrin receptor. Adv Exp Med Biol 356:61-68.
Finch C.A., Harker L.A., Cook J.D. (1977) Kinetics of the formed elements of human blood. Blood 50:699-707.
Kuiper-Kramer E.P., Coenen J.L., Huisman C.M., Abbes A., Van Raan J., Van Eijk H.G. (1998) Relationship between soluble transferrin receptors in serum and membrane-bound transferrin receptors. Acta Haematol 99:8-11.
Parisotto R., Gore C.J., Emslie K.R. (2000) A novel method utilising markers of altered erythropoiesis for the detection of recombinant human erythropoietin abuse in athletes. Haematologica 85:564-572.
