Phagocytosis and stimulation of the respiratory burst by phorbol diester initiate S-thiolation of specific proteins in macrophages.
Addition of chemical oxidants to cells in culture has been shown to induce binding of low-molecular-weight thiols to reactive sulfhydryls on proteins in a process termed S-thiolation. We found that stimulation of the respiratory burst in mouse macrophages, with release of O2-, resulted in S-thiolation of several proteins, most prominently three with molecular weights of 74, 33, and 22 kDa. One protein (28 kDa) was S-thiolated without addition of an exogenous stimulus. Exposure of cells to concentrations of hydrogen peroxide like those released in the respiratory burst induced S-thiolation of these same proteins. S-thiolation and release of O2- began at approximately the same time. Stimulation of LPS-elicited macrophages induced prominent S-thiolation of three different proteins (38, 30, and 21 kDa). Under the conditions of these experiments, there was no detectable increase in glutathione disulfide and a negligible decrease in glutathione, which suggests that S-thiolation can occur without significant perturbation of the glutathione peroxidase/reductase cycle. S-thiolation of proteins could help protect the macrophage against the autoxidative damage associated with the respiratory burst. Modification of specific proteins by S-thiolation might serve to modulate cellular metabolic events.
Rokutan
K
K
Department of Pediatrics, University of Pennsylvania, Philadelphia 19104.
Thomas
J A
JA
Johnston
R B
RB
D000818:Animals; D004220:Disulfides / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000502:physiology*; D051379:Mice; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010587:Phagocytosis; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004220:Disulfides; D008070:Lipopolysaccharides; D011506:Proteins; D013438:Sulfhydryl Compounds; D013481:Superoxides; D005978:Glutathione; D013755:Tetradecanoylphorbol Acetate