TY - JOUR T1 - Modification of Heat Shock Protein 90 by 4-Hydroxynonenal in a Rat Model of Chronic Alcoholic Liver Disease JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 8 LP - 15 DO - 10.1124/jpet.105.088088 VL - 315 IS - 1 AU - David L. Carbone AU - Jonathan A. Doorn AU - Zachary Kiebler AU - Brian R. Ickes AU - Dennis R. Petersen Y1 - 2005/10/01 UR - http://jpet.aspetjournals.org/content/315/1/8.abstract N2 - Lipid peroxidation during oxidative stress leads to increased concentrations of thiol-reactive α,β-unsaturated aldehyde, including 4-hydroxy-2-nonenal (4-HNE) and 4-oxo-2-nonenal (4-ONE). These aldehydes have a documented ability to disrupt protein function following adduct formation with specific residues. Therefore, to identify 4-HNE-modified proteins in a model of ethanol-induced oxidative stress, a proteomic approach was applied to liver fractions prepared from rats fed a combination high-fat/ethanol diet. The results revealed that essential 90-kDa heat shock protein (Hsp90) was consistently modified by 4-HNE in the alcohol-treated animals. In vitro chaperoning experiments using firefly luciferase as a client protein were then performed to assess the functional effect of 4-HNE modification on purified recombinant human Hsp90, modified with concentrations of this aldehyde ranging from 23 to 450 μM. Modification of Hsp90 with 4-ONE also led to significant inhibition of the chaperone. Because 4-HNE and 4-ONE react selectively with Cys, a thiol-specific mechanism of inhibition was suggested by these data. Therefore, thiol sensitivity was confirmed following treatment of Hsp90 with the specific thiol modifier N-ethylmaleimide, which resulted in more than 99% inactivation of the chaperone by concentrations as low as 6 μM (1:1 M ratio). Finally, tryptic digest of 4-HNE-modified Hsp90 followed by liquid chromatography/tandem mass spectrometry peptide analysis identified Cys 572 as a site for 4-HNE modification. The results presented here thus establish that 4-HNE consistently modifies Hsp90 in a rat model of alcohol-induced oxidative stress and that the chaperoning activity of this protein is subject to dysregulation through thiol modification. The American Society for Pharmacology and Experimental Therapeutics ER -