Chaperone Heat Shock Protein 90 Mobilization and Hydralazine Cytoprotection against Acrolein-Induced Carbonyl Stress

Abstract

Toxic carbonyls such as acrolein participate in many degenerative diseases. Although the nucleophilic vasodilatory drug hydralazine readily traps such species under "test-tube" conditions, whether these reactions adequately explain its efficacy in animal models of carbonyl-mediated disease is uncertain. We have previously shown that hydralazine attacks carbonyl-adducted proteins in an "adduct-trapping" reaction that appears to take precedence over direct "carbonyl-sequestering" reactions, but how this reaction conferred cytoprotection was unclear. This study explored the possibility that by increasing the bulkiness of acrolein-adducted proteins, adduct-trapping might alter the redistribution of chaperones to damaged cytoskeletal proteins that are known targets for acrolein. Using A549 lung adenocarcinoma cells, the levels of chaperones heat shock protein (Hsp) 40, Hsp70, Hsp90, and Hsp110 were measured in intermediate filament extracts prepared after a 3-h exposure to acrolein. Exposure to acrolein alone modestly increased the levels of all four chaperones. Coexposure to hydralazine (10 -100 M) strongly suppressed cell ATP loss while producing strong adduct-trapping in intermediate filaments. Most strikingly, hydralazine selectively boosted the levels of cytoskeletal-associated Hsp90, including a high-mass species that was sensitive to the Hsp90 inhibitor 17-N-allylamino-17-demethoxygeldanamycin. Biochemical fractionation of acrolein-and hydralazine-treated cells revealed that hydralazine likely promoted Hsp90 migration from cytosol into other subcellular compartments. A role for Hsp90 mobilization in cytoprotection was confirmed by the finding that brief heat shock treatment suppressed acute acrolein toxicity in A549 cells. Taken together, these findings suggest that by increasing the steric bulk of carbonyl-adducted proteins, adduct-trapping drugs trigger the intracellular mobilization of the key molecular chaperone Hsp90.

Molecular Mechanisms of Acrolein Toxicity: Relevance to Human Disease

“…Burcham et al showed in mouse hepatocytes that exposure to allyl alcohol and its metabolite acrolein led to protein carbonylation, which correlated with hepatocyte death. They later showed that the acrolein scavenger hydralazine effectively trapped acrolein adducts in vivo to reduce allyl alcoholmediated hepatotoxicity in mice, and that mobilization of the chaperone protein HSP90 was protective against acroleininduced carbonylation (Burcham et al, 2012). Acrolein was suggested to play a role in liver injury in a murine model of early alcoholic liver disease and two novel in vivo protein targets for acrolein were identified: neutral alpha-glucosidase AB and nesprin-1 (Galligan et al, 2012).…”

Catecholamine autotoxicity. Implications for pharmacology and therapeutics of Parkinson disease and related disorders

“…Treatment with aldehyde scavengers such as hydralazine is a possibility being explored (Kaminskas et al, 2004; Burcham et al, 2012). Major challenges in applying these approaches are developing drugs that cross the blood-brain barrier and relatively selectively affect the target cells.…”

Alterations in the proteome of the respiratory tract in response to single and multiple exposures to naphthalene

“…Furthermore, recent studies have shown that several of the HSPs are adducted by 4‐hydroxynonenal, a reactive breakdown product of lipid peroxidation , and that siRNA knockdown of the transcription factor, HSF1, whose translocation to the nucleus is controlled by several of the HSPs markedly enhances the loss in cell viability associated with 4‐hydroxynonenal exposure . Likewise, brief treatment of A549 lung cells with heat altered the distribution of HSP 90 to intermediate filaments and this correlated well with protection from another Michael adducting carbonyl, acrolein . Finally, HSP 70i knockout mice are considerably more susceptible to the hepatotoxic effects of acetaminophen, a bioactivated liver toxicant .…”