Interleukin-5 mRNA stability in human T cells is regulated differently than interleukin-2, interleukin-3, interleukin-4, granulocyte/macrophage colony-stimulating factor, and interferon-gamma.
Interleukin-5 (IL-5) transcriptional activation and mRNA stability were investigated in a human TH0 T-cell clone (SP-B21) and in nonclonal CD4 TH2 cells, differentiated in vitro from peripheral blood T cells. Cells were stimulated with alpha-CD3 monoclonal antibody (mAb) with and without alpha-CD28 mAb. Comparison to other cytokine genes revealed aspects of mRNA regulation unique to IL-5. The half-life (t1/2) of IL-5 mRNA, determined by addition of actinomycin D (ActinoD) or cyclosporin A (CSA) was longer (by >= 2 h) than that of IL-2, IL-3, IL-4, interferon-gamma, or granulocyte/macrophage colony-stimulating factor. With the exception of IL-5, t1/2 values were significantly shorter with CSA as the transcriptional inhibitor than with ActinoD. The t1/2 value of IL-5 mRNA, but not the other cytokine transcripts, determined with either ActinoD or CSA, was longer than predicted from the kinetics of steady-state mRNA decline. Co-stimulation of both cell types with alpha-CD28 mAb increased the stability of cytokine transcripts weakly, and IL-5 remained the most stable transcript. Thus, the degradation pathway that targets IL-5 is distinct from the other cytokine transcripts measured and involves proteins whose transcription is blocked by ActinoD and CSA. From examination of the levels of transcription initiation (nuclear run-on assay) and steady-state mRNA attained in cultures stimulated in the presence of the protein synthesis inhibitor, cycloheximide, only IL-5 transcription initiation had an absolute dependency on new protein synthesis.
Umland
S P
SP
Schering-Plough Research Institute, Kenilworth, New Jersey, USA.
Razac
S
S
Shah
H
H
Nahrebne
D K
DK
Egan
R W
RW
Billah
M M
MM
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D018106:CD28 Antigens / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics*; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007371:Interferon-gamma / Q000235:genetics*; D007376:Interleukin-2 / Q000235:genetics; D007377:Interleukin-3 / Q000235:genetics; D015847:Interleukin-4 / Q000235:genetics; D015848:Interleukin-5 / Q000096:biosynthesis / Q000235:genetics; D007378:Interleukins / Q000235:genetics*; D007700:Kinetics; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D014158:Transcription, Genetic / Q000276:immunology
D000911:Antibodies, Monoclonal; D018106:CD28 Antigens; D017252:CD3 Complex; D007166:Immunosuppressive Agents; D007376:Interleukin-2; D007377:Interleukin-3; D015848:Interleukin-5; D007378:Interleukins; D019384:Nucleic Acid Synthesis Inhibitors; D012333:RNA, Messenger; D003609:Dactinomycin; D015847:Interleukin-4; D007371:Interferon-gamma; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D016572:Cyclosporine