title: Mining microarray data to identify transcription factors expressed in naïve resting but not activated T lymphocytes.
abstract: Transcriptional repressors controlling the expression of cytokine genes have been implicated in a variety of physiological and pathological phenomena. An unknown repressor that binds to the distal NFAT element of the interleukin-2 (IL-2) gene promoter in naive T-helper lymphocytes has been implicated in autoimmune phenomena and has emerged as a potentially important factor controlling the latency of HIV-1. The aim of this paper was the identification of this repressor. We resorted to public microarray databases looking for DNA-binding proteins that are present in naïve resting T cells but are downregulated when the cells are activated. A Bayesian data mining statistical analysis uncovered 25 candidate factors. Of the 25, NFAT4 and the oncogene ets-2 bind to the common motif AAGGAG found in the HIV-1 LTR and IL-2 probes. Ets-2 binding site contains the three G's that have been shown to be important for binding of the unknown factor; hence, we considered it the likeliest candidate. Electrophoretic mobility shift assays confirmed cross-reactivity between the unknown repressor and anti-ets-2 antibodies, and cotransfection experiments demonstrated the direct involvement of Ets-2 in silencing the IL-2 promoter. Designing experiments for transcription factor analysis using microarrays and Bayesian statistical methodologies provides a novel way toward elucidation of gene control networks.
authors.affiliation: Laboratory of Hematology and Transfusion Medicine, University of Patras, Patras, Greece.
authors.forename: C
authors.initials: C
authors.lastname: Argyropoulos
authors.forename: G C
authors.initials: GC
authors.lastname: Nikiforidis
authors.forename: M
authors.initials: M
authors.lastname: Theodoropoulou
authors.forename: P
authors.initials: P
authors.lastname: Adamopoulos
authors.forename: S
authors.initials: S
authors.lastname: Boubali
authors.forename: T N
authors.initials: TN
authors.lastname: Georgakopoulos
authors.forename: F
authors.initials: F
authors.lastname: Paliogianni
authors.forename: A G
authors.initials: AG
authors.lastname: Papavassiliou
authors.forename: A
authors.initials: A
authors.lastname: Mouzaki
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000502:physiology*; D003627:Data Interpretation, Statistical; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000276:immunology; D006801:Humans; D007231:Infant, Newborn; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D013601:T-Lymphocytes / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D014157:Transcription Factors