Ferritin has traditionally been thought of as the intracellular storage protein for iron. It consists of 24 heavy (H) and light (L) subunits arranged in varying ratios depending on cell and tissue type. Recent studies have shown that ferritin is also present in the serum of normal individuals and several cell lines have been shown to bind ferritin. The goal of this study was to demonstrate and begin characterization of a ferritin binding protein in the mouse brain. Recombinant H-chain (rH) ferritin was iodinated using the chloramine-T method. Using this protein, saturable and reversible binding to membrane preparations was demonstrated with a Kd of 6-10nM. Competitive binding assays reveal that the ferritin binding protein shows preferential binding to rH-ferritin with rat liver ferritin competing to a lesser extent. Transferrin, recombinant L-chain ferritin, and bovine serum albumin were unable to compete with rH-ferritin for binding sites. Autoradiographic analysis indicates strong binding throughout white matter tracts and in scattered neurons throughout the gray matter. This distribution is in contrast to that of the transferrin receptor which is relatively low throughout white matter tracts. In vitro uptake of fluorescein conjugated rH-ferritin was evident in a single population of cells contained in mixed glial cultures. These cells were Ol positive, GFAP negative, and LDL negative, indicating that the cells were oligodendrocytes. Thus, we have identified a ferritin binding protein in the mouse brain which suggests a previously undescribed delivery system for iron in the brain. The different distribution for ferritin binding compared to transferrin receptors suggests a select population of cells in the brain uses the ferritin iron delivery system.
|Original language||English (US)|
|State||Published - Dec 1 1996|
All Science Journal Classification (ASJC) codes
- Molecular Biology