Recycling of RNA binding iron regulatory protein 1 into an aconitase after nitric oxide removal depends on mitochondrial ATP.
Iron regulatory proteins (IRPs) control iron metabolism by specifically interacting with iron-responsive elements (IREs) on mRNAs. Nitric oxide (NO) converts IRP-1 from a [4Fe-4S] aconitase to a trans-regulatory protein through Fe-S cluster disassembly. Here, we have focused on the fate of IRE binding IRP1 from murine macrophages when NO flux stops. We show that virtually all IRP-1 molecules from NO-producing cells dissociated from IRE and recovered aconitase activity after re-assembling a [4Fe-4S] cluster in vitro. The reverse change in IRP-1 activities also occurred in intact cells no longer exposed to NO and did not require de novo protein synthesis. Likewise, inhibition of mitochondrial aconitase via NO-induced Fe-S cluster disassembly was also reversed independently of protein translation after NO removal. Our results provide the first evidence of Fe-S cluster repair of NO-modified aconitases in mammalian cells. Moreover, we show that reverse change in IRP-1 activities and repair of mitochondrial aconitase activity depended on energized mitochondria. Finally, we demonstrate that IRP-1 activation by NO was accompanied by both a drastic decrease in ferritin levels and an increase in transferrin receptor mRNA levels. However, although ferritin expression was recovered upon IRP-1-IRE dissociation, expression of transferrin receptor mRNA continued to rise for several hours after stopping NO flux.
Bouton
Cécile
C
Institut de Chimie des Substances Naturelles, CNRS, Avenue de la Terrasse, 91190 Gif-sur-Yvette, France.
Chauveau
Marie-Jeanne
MJ
Lazereg
Sylvie
S
Drapier
Jean-Claude
JC
D000154:Aconitate Hydratase / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D005293:Ferritins / Q000378:metabolism; D035941:Iron Regulatory Protein 1; D035925:Iron-Regulatory Proteins; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D016601:RNA-Binding Proteins / Q000378:metabolism*; D011990:Receptors, Transferrin / Q000235:genetics
D035925:Iron-Regulatory Proteins; D007506:Iron-Sulfur Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011990:Receptors, Transferrin; D009569:Nitric Oxide; D000255:Adenosine Triphosphate; D005293:Ferritins; D003513:Cycloheximide; D000154:Aconitate Hydratase; D035941:Iron Regulatory Protein 1