Abstract
Mammalian cells express dozens of iron-containing proteins, yet little is known about the mechanism of metal ligand incorporation. Human poly (rC) binding protein 1 (PCBP1) is an iron chaperone that binds iron and delivers it to ferritin, a cytosolic iron storage protein. We have identified the iron-dependent prolyl hydroxylases (PHDs) and asparaginyl hydroxylase (FIH1) that modify hypoxia-inducible factor α (HIFα) as targets of PCBP1. Depletion of PCBP1 or PCBP2 in cells led to loss of PHD activity, manifested by reduced prolyl hydroxylation of HIF1α, impaired degradation of HIF1α through the VHL/proteasome pathway, and accumulation of active HIF1 transcription factor. PHD activity was restored in vitro by addition of excess Fe(II), or purified Fe-PCBP1, and PCBP1 bound to PHD2 and FIH1 in vivo. These data indicated that PCBP1 was required for iron incorporation into PHD and suggest a broad role for PCBP1 and 2 in delivering iron to cytosolic nonheme iron enzymes.
Copyright © 2011 Elsevier Inc. All rights reserved.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, N.I.H., Intramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Cell Line
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DNA-Binding Proteins
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Enzyme Activation
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Ferritins / metabolism
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Gene Expression
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Genes, Reporter
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Half-Life
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Heterogeneous-Nuclear Ribonucleoproteins / genetics
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Heterogeneous-Nuclear Ribonucleoproteins / metabolism*
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Humans
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Hydroxylation
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Hypoxia / metabolism
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Hypoxia-Inducible Factor 1, alpha Subunit / genetics
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Hypoxia-Inducible Factor 1, alpha Subunit / metabolism*
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Ion Transport / physiology*
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Iron / metabolism*
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Luciferases / analysis
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Molecular Chaperones / genetics
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Molecular Chaperones / metabolism
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Procollagen-Proline Dioxygenase / genetics
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Procollagen-Proline Dioxygenase / metabolism*
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Proteasome Endopeptidase Complex / metabolism
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Protein Binding
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RNA, Small Interfering
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RNA-Binding Proteins / genetics
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RNA-Binding Proteins / metabolism*
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Signal Transduction / physiology*
Substances
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DNA-Binding Proteins
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HIF1A protein, human
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Heterogeneous-Nuclear Ribonucleoproteins
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Hypoxia-Inducible Factor 1, alpha Subunit
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Molecular Chaperones
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PCBP1 protein, human
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PCBP2 protein, human
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RNA, Small Interfering
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RNA-Binding Proteins
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Ferritins
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Iron
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Luciferases
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Procollagen-Proline Dioxygenase
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Proteasome Endopeptidase Complex