Huntingtin inclusion bodies are iron-dependent centers of oxidative events.
Recently, we reported that the transient expression of huntingtin exon1 polypeptide containing polyglutamine tracts of various sizes (httEx1-polyQ) in cell models of Huntington disease generated an oxidative stress whose intensity was CAG repeat expansion-dependent. Here, we have analyzed the intracellular localization of the oxidative events generated by the httEx1-polyQ polypeptides. Analysis of live COS-7 cells as well as neuronal SK-N-SH and PC12 cells incubated with hydroethidine or dichlorofluorescein diacetate revealed oxidation of these probes at the level of the inclusion bodies formed by httEx1-polyQ polypeptides. The intensity and frequency of the oxidative events among the inclusions were CAG repeat expansion-dependent. Electron microscopic analysis of cell sections revealed the presence of oxidation-dependent morphologic alterations in the vicinity of httEx1-polyQ inclusion bodies. Moreover, a high level of oxidized proteins was recovered in partially purified inclusions. We also report that the iron chelator deferroxamine altered the structure, localization and oxidative potential of httEx1-polyQ inclusion bodies. Hence, despite the fact that the formation of inclusion bodies may represent a defense reaction of the cell to eliminate httEx1 mutant polypeptide, this phenomenon appears inherent to the generation of iron-dependent oxidative events that can be deleterious to the cell.
Firdaus
Wance J J
WJ
Laboratoire Stress Oxydant, Chaperons et Apoptose, Université Claude Bernard Lyon-1, Villeurbanne, France.
Wyttenbach
Andreas
A
Giuliano
Paola
P
Kretz-Remy
Carole
C
Currie
R William
RW
Arrigo
André-Patrick
AP
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D019556:COS Cells; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D003676:Deferoxamine / Q000378:metabolism; D005091:Exons; D006360:Heat-Shock Proteins / Q000378:metabolism; D006816:Huntington Disease / Q000378:metabolism*; D002479:Inclusion Bodies / Q000378:metabolism* / Q000648:ultrastructure; D007501:Iron / Q000378:metabolism*; D018613:Microscopy, Confocal; D010084:Oxidation-Reduction; D010617:Phenanthridines / Q000378:metabolism; D051381:Rats; D011993:Recombinant Fusion Proteins
D006360:Heat-Shock Proteins; D010617:Phenanthridines; D011993:Recombinant Fusion Proteins; C058428:hydroethidine; D007501:Iron; D003676:Deferoxamine; D000111:Acetylcysteine