Transforming Growth Factor-Beta 1 (TGF-β1) Promotes IL-2 mRNA Expression Through the Up-regulation of NF-κB, AP-1 and NF-AT in EL4 Cells1
- Dept. of Pharmacology & Toxicology and the Dept. of Pathology, Michigan State University, East Lansing, Michigan
Abstract
Transforming growth factor β1 (TGF-β1) has been previously shown to modulate interleukin 2 (IL-2) secretion by activated T-cells. In the present studies, we determined that TGF-β1 induced IL-2 mRNA expression in the murine T-cell line EL4, in the absence of other stimuli. IL-2 mRNA expression was significantly induced by TGF-β1 (0.1–1 ng/ml) over a relatively narrow concentration range, which led to the induction of IL-2 secretion. Under identical condition, we examined the effect of TGF-β1 on the activity of nuclear factor AT (NF-AT), nuclear factor κB (NF-κB), activator protein-1 (AP-1) and octamer, all of which contribute to the regulation of IL-2 gene expression. Electrophoretic mobility shift assays showed that TGF-β1 markedly increased NF-AT, NF-κB and AP-1 binding to their respective cognate DNA binding sites, whereas octamer binding remained constant, as compared with untreated cells. Employing a reporter gene expression system with p(NF-κB)3-CAT, p(NF-AT)3-CAT and p(AP-1)3-CAT, TGF-β1 treatment of transfected EL4 cells induced a dose-related increase in chloramphenicol acetyltransferase activity that correlated well with the DNA binding profile found in the electrophoretic mobility shift assay studies. These results show that TGF-β1, in the absence of any additional stimuli, up-regulates the activity of key transcription factors involved in IL-2 gene expression, including NF-AT, NF-κB and AP-1, to help promote IL-2 mRNA expression by EL4 cells.
Footnotes
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Send reprint requests to: Dr. Norbert Kaminski, Department of Pharmacology & Toxicology, B440 Life Science Bldg., Michigan State University, East Lansing, MI 48824.
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↵1 This work was supported by NIEHS Superfund Grant PO1 P42ES04911-08C.
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↵2 Present address: Dept. of Biological Sciences, Korea Advanced Institute of Science and Technology, Taejon, Korea.
- Abbreviations:
- NF-AT
- nuclear factor AT
- IL-2
- interleukin 2
- NF-κB
- nuclear factor κB
- AP-1
- activator protein-1
- Oct
- octamer
- FCS
- fetal calf serum
- EMSA
- electrophoretic mobility shift assay
- PMA
- phorbol-12-myristate-13-acetate
- CAT
- chloramphenicol acetyltransferase
- rcRNA
- recombinant RNA
- IS
- internal standard
- RT-PCR
- reverse transcriptase polymerase chain reaction
- FKBP12
- immunophilin-FKBP12
- TGF-β1
- transforming growth factor-beta 1
- lg
- immunoglobulin
- Th
- T helper cell
- IFN-γ
- interferon-gamma
- CD
- cluster designation
- RPMI
- Roswell Park Memorial Institute
- DEAE
- diethylaminoethyl
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- Received January 9, 1998.
- Accepted July 1, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
