Transcriptional regulation of cytokine genes in nontransformed T cells. Apparent constitutive signals in run-on assays can be caused by repeat sequences.
Cytokines are immunoregulatory proteins that are secreted by T lymphocytes and other cells upon activation. A controversy exists as to whether the induction of cytokine production is mediated at the transcriptional level by the initiation of RNA synthesis or at the post-transcriptional level by the enhancement of mRNA stability. We show that in a nontransformed T cell clone the induction of all of the cytokines that are analyzed in this report is mediated transcriptionally. We also found that a constitutive signal was seen in resting cells when the probes used in the nuclear run-on assay contained some potential cross-hybridizing sequences, for example a poly (A) tract in a cDNA probe. This observation could explain the constitutive signals seen in other studies that claim cytokine production is regulated by differential mRNA stability.
Laboratory of Cellular and Molecular Immunology, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD 20892.
K A
KA
Brorson
B
B
Beverly
S M
SM
Kang
M
M
Lenardo
R H
RH
Schwartz
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D002467:Cell Nucleus / Q000378:metabolism; D002999:Clone Cells; D016207:Cytokines / Q000235:genetics*; D015342:DNA Probes; D005786:Gene Expression Regulation; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000235:genetics; D007376:Interleukin-2 / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D013601:T-Lymphocytes / Q000502:physiology*; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D016207:Cytokines; D015342:DNA Probes; D007376:Interleukin-2; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D016178:Granulocyte-Macrophage Colony-Stimulating Factor