Ferroportin 1 (FPN1) is an iron exporter protein expressed in liver and duodenum, as well as in reticuloendothelial macrophages. Previously, we have shown that Divalent Metal Transporter 1 (DMT1) is expressed in late endosomes and lysosomes of the kidney proximal tubule (PT), the nephron segment responsible for the majority of solute reabsorption (1). We suggested that following receptor mediated endocytosis of transferrin filtered by the glomerulus, DMT1 exports iron liberated from transferrin into the cytosol. FPN1 is also expressed in the kidney yet its role remains obscure. As a first step towards determining the role of renal FPN1 we localized FPN1 in the rat PT. FPN1 was found to be located in association with the basolateral PT membrane and within the cytosolic compartment.FPN1 was not expressed on the apical brush-border membrane of rat PT cells. These data support a role for FPN1 in vectorial export of iron out of mammalian PT cells. Furthermore, under conditions of iron loading of cultured rat PT cells, FPN1 was trafficked to the plasma membrane suggesting a coordinated cellular response to export excess iron and limit cellular iron concentrations.
Newcastle University (2009) Proc Physiol Soc 16, C13
Oral Communications: Ferroportin 1 is expressed on basolateral membranes of kidney proximal tubule cells and iron excess increases FPN1 trafficking to the membrane
C. P. Smith1, W. Lui1, N. A. Wolff2, R. A. Fenton3, W. Lee2, F. Thévenod2
1. Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom. 2. Department of Physiology & Pathophysiology, University of Witten/Herdecke, Witten, Germany. 3. Institute of Anatomy, Building 233/234, , DK-8000 Aarhus, Denmark, University of Aarhus, Aarhus, Denmark.
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