| 19843705 |
Spiess PC, Morin D, Williams CR, Buckpitt AR: Protein Thiol Oxidation in Murine Airway Epithelial Cells in Response to Naphthalene or Diethyl Maleate. Am J Respir Cell Mol Biol. 2009 Oct 20.
Naphthalene is a semi-volatile aromatic hydrocarbon to which humans are exposed from a variety of sources. Naphthalene results in acute cytotoxicity to respiratory epithelium in rodents. Cytochrome P450-dependent metabolic activation to form reactive intermediates and loss of soluble cellular thiols (glutathione) are critical steps in naphthalene toxicity, but the precise mechanisms by which this chemical results in cellular injury remain unclear. Protein thiols are likely targets of reactive naphthalene metabolites. Loss of these, either through adduction or thiol oxidation mechanisms, may be important underlying mechanisms for naphthalene toxicity. To address the hypothesis that loss of thiols on specific cellular proteins is critical to naphthalene-induced cytotoxicity, we have compared reduced to oxidized thiol ratios in airway epithelial cell proteins isolated from lungs of mice treated with naphthalene or the nontoxic glutathione depletor, diethyl maleate. At 300 mg/kg doses, naphthalene administration resulted in > 85% loss of glutathione levels in the airway epithelium, which is similar to the loss observed following diethyl maleate treatment. Using differential fluorescent maleimide labeling followed by 2DE separation of proteins, we have identified more than 35 unique proteins which have treatment-specific differential sulfhydryl oxidation. At doses of naphthalene and diethyl maleate which produce similar levels of glutathione depletion, Cy3/Cy5 labeling ratios were statistically different for 16 non-redundant proteins in airway epithelium. Proteins identified include a zinc finger protein, several aldehyde dehydrogenase variants, beta-actin, and several other structural proteins. These studies show distinct patterns of protein thiol alterations with the non-cytotoxic diethyl maleate and the cytotoxic naphthalene. |
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