Tài liệu Báo cáo khoa học: Analysis of oxidative events induced by expanded polyglutamine huntingtin

Analysis of oxidative events induced by expanded

polyglutamine huntingtin exon 1 that are differentially

restored by expression of heat shock proteins or treatment

with an antioxidant

Wance J. J. Firdaus1

, Andreas Wyttenbach2

, Chantal Diaz-Latoud1

, R. W. Currie1,3

and Andre´-Patrick Arrigo1

1 Laboratoire Stress Oxydant, Chaperons et Apoptose, Centre de Ge´ne´tique Mole´ culaire et Cellulaire, Universite´ Claude Bernard Lyon-1,

Villeurbanne, France

2 Southampton Neuroscience Group, School of Biological Sciences, University of Southampton, UK

3 Department of Anatomy and Neurobiology, Dalhousie University, Halifax, Canada

Neuronal selective loss and formation of intraneuron￾al protein aggregates are characteristics of Hunting￾ton’s disease (HD), which is one of more than 10

known neurodegenerative disorders caused by abnor￾mally expanded polyglutamine polyQ tracts in the

diseased protein [1]. HD is a progressive, autosomal

dominant and hereditary neurodegenerative disorder

that induces a relatively selective loss of neurons in

striatum and cortex. The mutated gene involved in

HD encodes the 350 kDa huntingtin protein, an iron￾regulated neuronal protein implicated in vesicle traf￾ficking [2,3] that, if inactivated, results in impairment

of basic cellular processes [4]. The mutation is charac￾terized by the expansion of CAG triplets 17 codons

Keywords

heat shock proteins; huntingtin polyQ

inclusion bodies; oxidized proteins;

proteasome; reactive oxygen species

Correspondence

A.-P. Arrigo, Laboratoire Stress Oxydant,

Chaperons et Apoptose, CNRS UMR 5534,

Centre de Ge´ne´tique Mole´ culaire et

Cellulaire, Universite´ Claude Bernard Lyon-1,

43 Blvd du 11 Novembre, 69622

Villeurbanne Ce´dex, France

Fax: +33 472 440555

Tel: +33 472 432685

E-mail: [email protected]

(Received 16 February 2006, revised

20 April 2006, accepted 12 May 2006)

doi:10.1111/j.1742-4658.2006.05318.x

We recently reported that the transient expression of polyglutamine tracts

of various size in exon 1 of the huntingtin polypeptide (httEx1) generated

abnormally high levels of intracellular reactive oxygen species that directly

contributed to cell death. Here, we compared the protection generated by

heat shock proteins to that provided by the antioxidant agent N-acetyl-l￾cysteine. In cells expressing httEx1 with 72 glutamine repeats (httEx1-72Q),

the overexpression of Hsp27 or Hsp70 plus Hdj-1(Hsp40) or treatment of

the cells with N-acetyl-l-cysteine inhibited not only mitochondrial mem￾brane potential disruption but also the increase in reactive oxygen species,

nitric oxide and protein oxidation. However, only heat shock proteins and

not N-acetyl-l-cysteine reduced the size of the inclusion bodies formed by

httEx1-72Q. In cells expressing httEx1 polypeptide with 103 glutamine

repeats (httEx1-103Q), heat shock proteins neither decreased oxidative

damage nor reduced the size of the inclusions. In contrast, N-acetyl-l-cys￾teine still efficiently decreased the oxidative damage induced by httEx1-

103Q polypeptide without altering the inclusions. N-Acetyl-l-cysteine was

inactive with regard to proteasome inhibition, whereas heat shock proteins

partially restored the caspase-like activity of this protease. These observa￾tions suggest some relationships between the presence of inclusion bodies

and the oxidative damage induced by httEx1-polyQ.

Abbreviations

DCFH-DA, 2¢,7¢-dichlorofluorescein diacetate; 2,4-DNPH, 2,4-dinitrophenyl hydrazine; EGFP, enhanced green fluorescent protein; FCCP,

p-trifluoromethoxy carbonyl cyanide phenylhydrazone; HA, hemagglutinin; HD, Huntington’s disease; HE, dihydroethidine; Hsp, heat shock

protein; NAC, N-acetyl-L-cysteine; polyQ, polyglutamine tract; ROS, reactive oxygen species.

3076 FEBS Journal 273 (2006) 3076–3093 ª 2006 The Authors Journal compilation ª 2006 FEBS