title: The FLI-1 transcription factor is a short-lived phosphoprotein in T cells.
abstract: The FLI-1 transcription factor is a member of the ETS gene family, most closely related to ERG. In this study, the FLI-1 protein products were characterized using a specific monoclonal antibody previously developed against bacterially expressed protein. In the human T-cell line Jurkat, both isoforms of FLI-1, p51 and p48, are phosphorylated, primarily on serine residues. FLI-1 phosphorylation is increased by a Ca(2+)-mediated process, and inhibitor studies indicate that protein phosphatase 2A, at least in part, controls FLI-1 phosphorylation level. FLI-1 phosphorylation is not stimulated by phorbal 12-myristate 13-acetate (PMA), a protein kinase C activator, and in this it differs from ERG protein phosphorylation. The p51 isoform has a half-life of 105 min, and p48 has a half-life of 80 min; in contrast, the ERG protein is much more stable with a half-life of 21 h. Newly synthesized FLI-1 protein decreased during human T cell activation. Our data suggest that although the FLI-1 and ERG genes are highly homologous, their distinct properties may contribute to their different roles in gene regulation.
authors.affiliation: Medical Research Service, Ralph H. Johnson VAMC, Department of Medicine, Division of Rheumatology & Immunology, 96 Jonathan Lucas St., PO Box 250623, Charleston, SC 29425, USA. zhangjo@musc.edu
authors.forename: Xian K
authors.initials: XK
authors.lastname: Zhang
authors.forename: Dennis K
authors.initials: DK
authors.lastname: Watson
mesh_terms: D000911:Antibodies, Monoclonal; D002193:Cantharidin / Q000494:pharmacology; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D016147:Genes, Tumor Suppressor; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D054648:Protein Phosphatase 2; D011499:Protein Processing, Post-Translational; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins
chemical_list: D000911:Antibodies, Monoclonal; D004268:DNA-Binding Proteins; D010750:Phosphoproteins; D020033:Protein Isoforms; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; C115051:TP63 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D015759:Ionomycin; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D002193:Cantharidin; D013755:Tetradecanoylphorbol Acetate