Molecular events involved in regulating human interferon-gamma gene expression during T cell activation.
The human T cell line Jurkat is a useful model of regulated T cell activation. After in vitro treatment of Jurkat with phytohemagglutinin (PHA) and phorbol ester (PMA), RNA transcripts of both interleukin 2 (IL 2) and interferon-gamma (IFN-gamma) appear, followed by secretion of both biologically active lymphokines. Employing the nuclear run-on technology, we first confirmed that the expression of both lymphokines after T cell activation is regulated at the transcriptional level. By using the recombinant approach of DNase I hypersensitivity mapping, we had previously localized a structurally unique, lymphocyte-specific genomic domain in the first intron of the human IFN-gamma gene that correlated with the transcriptional potential of that gene. By using several T cell lines that differ in their inducible expression of IFN-gamma, we have now localized several additional structural domains within the human IFN-gamma gene that appear to be coordinately involved in regulating expression. These include: a distal 5' flanking region site also seen only in T lymphocytes that can express the gene, a proximal, promoter-associated site that appears only after PHA/PMA-mediated IFN-gamma induction, and a second intronic site seen only in T cells whose IFN-gamma gene is selectively inactive. Collectively, our data suggest that T cell activation is accompanied by transcriptional level induction of lymphokine gene expression. In the case of IFN-gamma, T cell nuclei possess specific structural domains within the gene itself that seem to participate both positively and negatively in activation-mediated regulatory events.
D001483:Base Sequence; D002460:Cell Line; D002843:Chromatin / Q000648:ultrastructure; D002874:Chromosome Mapping; D003850:Deoxyribonuclease I; D005786:Gene Expression Regulation; D005809:Genes, Regulator; D006801:Humans; D007371:Interferon-gamma / Q000235:genetics*; D008213:Lymphocyte Activation; D012689:Sequence Homology, Nucleic Acid; D013601:T-Lymphocytes / Q000502:physiology*; D014158:Transcription, Genetic
D002843:Chromatin; D007371:Interferon-gamma; D003850:Deoxyribonuclease I