title: Proteomic and biochemical analysis of 14-3-3-binding proteins during C2-ceramide-induced apoptosis.
abstract: 14-3-3 is a family of proteins comprising several isoforms that, in many cases, promote cell survival by association with proapoptotic proteins. This study was designed to obtain further understanding of the 14-3-3 role in apoptosis regulation, by analyzing apoptosis-related protein-14-3-3 interactions. Western blot analysis of an eluted fraction from the 14-3-3-affinity chromatography column identified proapoptotic proteins as receptor-interacting protein 3 and Bcl-2-antagonist/killer as new phophorylation-dependent 14-3-3-binding proteins under physiological conditions. The apoptosis inducer C2-ceramide promoted decay of the 14-3-3-binding signal of protein cell extracts. Investigation of the role of 14-3-3 in C2-ceramide-induced apoptosis showed that depletion of the 14-3-3zeta isoform sensitized to cell death, whereas overexpression of this isoform delayed cell death. A combination of tandem affinity purification and liquid chromatography-tandem MS techniques identified 15 proteins involved in cell survival processes whose 14-3-3-binding status changed during C2-ceramide-induced apoptosis. Under physiological conditions, desmin was clearly identified as a new 14-3-3-interactor protein, and vasodilator-stimulated phosphoprotein, nucleophosmin and calmodulin, whose 14-3-3 binding was suggested by others on the basis of MS analysis, were confirmed here as phosphorylation-dependent 14-3-3-associated proteins. Interestingly, proteins related to the regulation of DNA double-strand break repair in the early stages of apoptosis, such as DNA-dependent protein kinase, or the regulation of cell shrinkage during apoptosis, such as vasodilator-stimulated phosphoprotein and death promoters like receptor-interacting protein 3, were identified as 14-3-3-associated proteins whose 14-3-3-binding status changed when apoptosis was initiated. The functional diversity of these identified proteins suggests that 14-3-3 may regulate the apoptotic process through new mechanisms, in addition to others previously characterized.
authors.affiliation: Centro Andaluz de Biología Molecular y Medicina Regenerativa, Consejo Superior de Investigaciones Científicas, Sevilla, Spain. merce_pozo@yahoo.es
authors.forename: Mercedes
authors.initials: M
authors.lastname: Pozuelo-Rubio
mesh_terms: D048948:14-3-3 Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology*; D015153:Blotting, Western; D053181:Caspase 8 / Q000378:metabolism; D045744:Cell Line, Tumor; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D011485:Protein Binding; D040901:Proteomics; D034741:RNA, Small Interfering; D015203:Reproducibility of Results; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D048948:14-3-3 Proteins; D004791:Enzyme Inhibitors; C064769:N-acetylsphingosine; D034741:RNA, Small Interfering; D049452:Green Fluorescent Proteins; D053181:Caspase 8; D013110:Sphingosine