title: Post-translational disulfide modifications in cell signaling--role of inter-protein, intra-protein, S-glutathionyl, and S-cysteaminyl disulfide modifications in signal transmission.
abstract: Cell signaling entails a host of post-translational modifications of effector-proteins. These modifications control signal transmission by regulating the activity, localization or half-life of the effector-protein. Prominent oxidative modifications induced by cell-signaling reactive oxygen species (ROS) are cysteinyl modifications such as S-nitrosylation, sulfenic acid and disulfide formation. Disulfides protect protein sulfhydryls against oxidative destruction and simultaneously influence cell signaling by engaging redox-regulatory sulfhydryls in effector-proteins. The types of disulfides implicated in signaling span (1) protein S-glutathionylation, e.g. as a novel mode of Ras activation through S-glutathionylation at Cys-118 in response to a hydrogen-peroxide burst, (2) intra-protein disulfides, e.g. in the regulation of the stability of the protein phosphatase Cdc25C by hydrogen-peroxide, (3) inter-protein disulfides, e.g. in the hydrogen peroxide-mediated inactivation of receptor protein-tyrosine phosphatase alpha (RPTPalpha) by dimerization and (4) protein S-cysteaminylation by cystamine. Cystamine is a byproduct of pantetheinase-catalyzed pantothenic acid recycling from pantetheine for biosynthesis of Coenzyme A (CoA), a ubiquitous and metabolically indispensable cofactor. Cystamine inactivates protein kinase C-epsilon (PKCepsilon), gamma-glutamylcysteine synthetase and tissue transglutaminase by S-cysteaminylation-triggered mechanisms. The importance of protein S-cysteaminylation in signal transmission in vivo is evident from the ability of cystamine administration to rescue the intestinal inflammatory-response deficit of pantetheinase knockout mice. These mice lack the predominant epithelial pantetheinase isoform and have sharply reduced levels of cystamine/cysteamine in epithelial tissues. In addition, intraperitoneal administration of cystamine significantly delays neurodegenerative pathogenesis in a Huntington's disease mouse model. Thus, cystamine may serve as a prototype for the development of novel therapeutics that target effector-proteins regulated by S-cysteaminylation.
authors.affiliation: U.T.M.D. Anderson Cancer Center, Houston, TX, USA. cobrian@mdanderson.org
authors.forename: Catherine A
authors.initials: CA
authors.lastname: O'Brian
authors.forename: Feng
authors.initials: F
authors.lastname: Chu
mesh_terms: D000818:Animals; D003538:Cystamine / Q000378:metabolism*; D004220:Disulfides / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D006816:Huntington Disease / Q000378:metabolism; D051379:Mice; D010084:Oxidation-Reduction; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D011506:Proteins / Q000378:metabolism; D017382:Reactive Oxygen Species; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D004220:Disulfides; D011506:Proteins; D017382:Reactive Oxygen Species; D005978:Glutathione; D003538:Cystamine