Immunolocalization of transferrin and transferrin receptor in mouse small intestinal absorptive cellsDS Levine and JW Woods Department of Medicine, University of Washington, Seattle 98195. The mechanisms by which the duodenal mucosa absorbs iron are unknown. Insorption into absorptive cells of luminal iron bound to transferrin via receptor-mediated endocytosis has been hypothesized, but transferrin and transferrin receptor are absent in apical microvillous brush borders of small bowel biopsies taken from fasted patients and normal volunteers. We hypothesized that a normal iron-containing diet might induce the transient appearance of transferrin and transferrin receptor in apical brush borders of small intestinal absorptive cells in a normal mouse that was provided iron-containing chow until the moment of sacrifice. Light and electron microscopic immunolocalization of transferrin and transferrin receptor in proximal small intestinal absorptive cells was limited to basolateral membranes and coated pits of cells predominantly in the crypts and basal regions of the villi. Transferrin and transferrin receptor were not detected in apical microvillous brush border membranes of these enterocytes. In parallel immunolocalization protocols designed to show the ability to immunodetect other antigens at these locations, maltase and proteoglycan were demonstrated in apical microvillous brush border membranes and in basolateral membranes, respectively, in absorptive cells of small intestinal villous tip, base, and crypt regions. Furthermore, transferrin and transferrin receptor were immunolocalized in hepatocyte sinusoidal microvillus membranes. We conclude that food does not induce the appearance of immunodetectable transferrin and transferrin receptor in the apical microvilli of small intestinal absorptive cells and, therefore, that these iron transport proteins are not involved in the apical microvillous membrane transport of luminal dietary iron.
Volume 38,
Issue 6,
pp. 851-858,
06/01/1990
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J. S. L. Parker, W. J. Murphy, D. Wang, S. J. O'Brien, and C. R. Parrish Canine and Feline Parvoviruses Can Use Human or Feline Transferrin Receptors To Bind, Enter, and Infect Cells J. Virol., April 15, 2001; 75(8): 3896 - 3902. [Abstract] [Full Text] |
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C. N. Roy and C. A. Enns Iron homeostasis: new tales from the crypt Blood, December 15, 2000; 96(13): 4020 - 4027. [Abstract] [Full Text] [PDF] |
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S. Parkkila, A. Waheed, R. S. Britton, J. N. Feder, Z. Tsuchihashi, R. C. Schatzman, B. R. Bacon, and W. S. Sly Immunohistochemistry of HLA-H, the protein defective in patients with hereditary hemochromatosis, reveals unique pattern of expression in gastrointestinal tract PNAS, March 18, 1997; 94(6): 2534 - 2539. [Abstract] [Full Text] [PDF] |
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R. Roberts, R. Fine, and A Sandra Receptor-mediated endocytosis of transferrin at the blood-brain barrier J. Cell Sci., January 2, 1993; 104(2): 521 - 532. [Abstract] [PDF] |
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