title: Regulation of T lymphocyte proliferation. Interleukin 2-mediated induction of c-myb gene expression is dependent on T lymphocyte activation state.
abstract: We previously reported that with time, after antigenic stimulation of antigen-regulated murine T lymphocyte clones, total IL-2-R expression decayed 10-50-fold, commensurate with a decline in the ability of the cells to proliferate to IL-2. However, late after antigenic stimulation, when the cells were refractory to the IL-2-proliferative stimulus, high levels of high affinity IL-2-R remained. In this report we further explore the basis of unresponsiveness to IL-2 in the quiescent clones. We show that the proto-oncogene c-myc is induced in the late cell population by IL-2 to comparable levels observed early after antigen stimulation. IL-2-dependent c-myb induction, however, is seen only early after activation but not in the late-activated population. Analysis of the IL-2-dependent expression of c-myb mRNA with time after antigenic stimulation showed that steadystate c-myb expression declines dramatically with kinetics closely paralleling a decay in IL-2-dependent proliferative ability. In contrast, steadystate c-myc expression remains high throughout this period. Expression of c-myb is critical for proliferation of these cells since antisense oligodeoxy-nucleotide to c-myb can inhibit their IL-2-dependent proliferation. We present evidence for a pathway of c-myb induction via the TCR that is independent of the IL-2/IL-2-R interaction. In addition, the inhibition of IL-2-R-induced c-myb expression by 2-aminopurine and enhanced induction of c-myb via the TCR demonstrate that TCR activation and IL-2-R activation lead to induction of c-myb by different mechanisms.
authors.affiliation: Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110.
authors.forename: A M
authors.initials: AM
authors.lastname: Churilla
authors.forename: T J
authors.initials: TJ
authors.lastname: Braciale
authors.forename: V L
authors.initials: VL
authors.lastname: Braciale
mesh_terms: D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D002999:Clone Cells; D015342:DNA Probes; D007376:Interleukin-2 / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D008213:Lymphocyte Activation; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D020598:Proto-Oncogene Proteins c-myb; D011519:Proto-Oncogenes / Q000187:drug effects*; D015375:Receptors, Interleukin-2 / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D014158:Transcription, Genetic
chemical_list: D015342:DNA Probes; D007376:Interleukin-2; D011518:Proto-Oncogene Proteins; D020598:Proto-Oncogene Proteins c-myb; D015375:Receptors, Interleukin-2