Uncoupling of c-myc mRNA expression from G1 events in human T lymphocytes.
Normal human T-cells were grown in interleukin 2 (IL-2) until they became quiescent. Treatment with the phorbol-ester Phorbol-12, 13-dibutyrate (PBt2) made the cells competent to respond to IL-2 by expression of high affinity IL-2 receptors. These cells could be considered as G1 cells as they also displayed increased uridine incorporation, but they did not proceed into the S phase. c-myc mRNA expression was induced both by the phorbol ester and by IL-2, provided that receptors were present. A pulse with PBt2 increased c-myc mRNA transiently, while responsiveness to IL-2 and IL-2 receptors was maintained long after c-myc expression had subsided. IL-2 induced and maintained c-myc mRNA levels for more than 10h. Thus c-myc mRNA was expressed both when the cells were made competent to respond to the growth factor and when the cells progressed towards and through the S phase. In T lymphocytes c-myc mRNA expression was thus regulated in a complex way and was not necessary for maintaining G1 functions.
D005786:Gene Expression Regulation; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D007399:Interphase; D010703:Phorbol Esters / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D011519:Proto-Oncogenes; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D011971:Receptors, Immunologic / Q000378:metabolism; D015375:Receptors, Interleukin-2; D013601:T-Lymphocytes / Q000502:physiology*; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects
D007376:Interleukin-2; D010703:Phorbol Esters; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2