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Ferroportin-mediated mobilization of ferritin iron precedes ferritin degradation by the proteasome.

Authors
  • De Domenico, Ivana
  • Vaughn, Michael B
  • Li, Liangtao
  • Bagley, Dustin
  • Musci, Giovanni
  • Ward, Diane M
  • Kaplan, Jerry
Type
Published Article
Journal
The EMBO journal
Publication Date
Nov 15, 2006
Volume
25
Issue
22
Pages
5396–5404
Identifiers
PMID: 17082767
Source
Medline
License
Unknown

Abstract

Ferritin is a cytosolic molecule comprised of subunits that self-assemble into a nanocage capable of containing up to 4500 iron atoms. Iron stored within ferritin can be mobilized for use within cells or exported from cells. Expression of ferroportin (Fpn) results in export of cytosolic iron and ferritin degradation. Fpn-mediated iron loss from ferritin occurs in the cytosol and precedes ferritin degradation by the proteasome. Depletion of ferritin iron induces the monoubiquitination of ferritin subunits. Ubiquitination is not required for iron release but is required for disassembly of ferritin nanocages, which is followed by degradation of ferritin by the proteasome. Specific mammalian machinery is not required to extract iron from ferritin. Iron can be removed from ferritin when ferritin is expressed in Saccharomyces cerevisiae, which does not have endogenous ferritin. Expressed ferritin is monoubiquitinated and degraded by the proteasome. Exposure of ubiquitination defective mammalian cells to the iron chelator desferrioxamine leads to degradation of ferritin in the lysosome, which can be prevented by inhibitors of autophagy. Thus, ferritin degradation can occur through two different mechanisms.

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