An iron-responsive element type II in the 5'-untranslated region of the Alzheimer's amyloid precursor protein transcript.
Iron-responsive elements (IREs) are the RNA stem loops that control cellular iron homeostasis by regulating ferritin translation and transferrin receptor mRNA stability. We mapped a novel iron-responsive element (IRE-Type II) within the 5'-untranslated region (5'-UTR) of the Alzheimer's amyloid precursor protein (APP) transcript (+51 to +94 from the 5'-cap site). The APP mRNA IRE is located immediately upstream of an interleukin-1 responsive acute box domain (+101 to +146). APP 5'-UTR conferred translation was selectively down-regulated in response to intracellular iron chelation using three separate reporter assays (chloramphenicol acetyltransferase, luciferase, and red fluorescent protein reflecting an inhibition of APP holoprotein translation in response to iron chelation. Iron influx reversed this inhibition. As an internal control to ensure specificity, a viral internal ribosome entry sequence was unresponsive to intracellular iron chelation with desferrioxamine. Using RNA mobility shift assays, the APP 5'-UTRs, encompassing the IRE, bind specifically to recombinant iron-regulatory proteins (IRP) and to IRP from neuroblastoma cell lysates. IRP binding to the APP 5'-UTR is reduced after treatment of cells with desferrioxamine and increased after interleukin-1 stimulation. IRP binding is abrogated when APP cRNA probe is mutated in the core IRE domain (Delta4 bases:Delta83AGAG86). Iron regulation of APP mRNA through the APP 5'-UTR points to a role for iron in the metabolism of APP and confirms that this RNA structure can be a target for the selection of small molecule drugs, such as desferrioxamine (Fe chelator) and clioquinol (Fe, Cu, and Zn chelator), which reduce Abeta peptide burden during Alzheimer's disease.
Genetics and Aging Research Unit, Department of Psychiatry, Massachusetts General Hospital, Charlestown, Massachusetts 02129-4404, USA.
Jack T
JT
Rogers
Jeffrey D
JD
Randall
Catherine M
CM
Cahill
Paul S
PS
Eder
Xudong
X
Huang
Hiromi
H
Gunshin
Lorene
L
Leiter
Jay
J
McPhee
Satinder S
SS
Sarang
Tada
T
Utsuki
Nigel H
NH
Greig
Debomoy K
DK
Lahiri
Rudolph E
RE
Tanzi
Ashley I
AI
Bush
Tony
T
Giordano
Steve R
SR
Gullans
D020121:5' Untranslated Regions / Q000235:genetics*; D000544:Alzheimer Disease / Q000235:genetics / Q000378:metabolism; D016564:Amyloid beta-Protein Precursor / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D007464:Clioquinol / Q000378:metabolism; D003676:Deferoxamine / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D007502:Iron Chelating Agents / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D020218:Response Elements / Q000235:genetics*; D014407:Tumor Cells, Cultured
D020121:5' Untranslated Regions; D016564:Amyloid beta-Protein Precursor; D007375:Interleukin-1; D007502:Iron Chelating Agents; D012333:RNA, Messenger; D007464:Clioquinol; D007501:Iron; D008274:Magnesium; D003676:Deferoxamine; D002118:Calcium