Evidence That Gαq-Coupled Receptor-Induced Interleukin-6 mRNA in Vascular Smooth Muscle Cells Involves the Nuclear Factor of Activated T Cells
- Department of Pharmacology and Graduate Program in Molecular and Systems Pharmacology, Emory University School of Medicine, Atlanta, Georgia
Abstract
The immunosuppressant cyclosporin A inhibits transcription mediated by the nuclear factor of activated T-cells (NFAT), a key regulator of cytokine gene expression in lymphocytes that integrates phospholipase C signaling. NFAT is also expressed in vascular smooth muscle cells, but the genes it regulates there are unknown. Here we show that Gαq-coupled P2Y nucleotide receptor signaling in rat vascular smooth muscle cells increases NFAT-mediated luciferase reporter expression. It also induces interleukin (IL)-6 gene expression but not other cytokine mRNAs including IL-1, IL-2, IL-3, IL-4, IL-10, γ-interferon, tumor necrosis factor-α, or tumor necrosis factor-β. IL-6 mRNA induction by UTP is more rapid and transient then that caused by IL-1β stimulation and is partially blocked by cyclosporin A or by expression of atrans-dominant NFAT inhibitor. Expression of recombinant NFATc1 markedly augments IL-6 mRNA induction by these and other agonists, which is partially attributable to NFAT-regulated paracrine mediators. However, trans-dominant NFκB inhibitors strongly interfere with IL-6 mRNA induction both by IL-1β and by UTP, which synergistically evoke IL-6 mRNA expression. These findings suggest that NFAT is among the cofactors involved in NFκB-dependent IL-6 gene induction by Ca2+-mobilizing receptors in vascular smooth muscle cells.
Footnotes
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Send reprint requests to: T. J. Murphy Ph.D., Department of Pharmacology, Emory University School of Medicine, 5031 O.W. Rollins Research Building, Atlanta, GA 30322. E-mail:medtjm{at}emory.edu
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Supported by Grants HL52810 and HL56107 from the National Heart, Lung, and Blood Institute. T.J.M. is an Established Investigator of the American Heart Association. A.M.R. is supported by a National Institutes of Health predoctoral training grant (GM08602).
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↵1 NFAT nomenclature is unsettled. Synonyms of the five known genes are: 1) NFATc1, NFAT2, NFATc; 2) NFATc2, NFAT1, NFATp; 3) NFATc3, NFAT4, NFATx; 4) NFATc4, NFAT3; and 5) NFAT5.
- Abbreviations:
- CsA
- cyclosporin A
- NFAT
- nuclear factor of activated T-cells
- PLC
- phospholipase C
- PDGF
- platelet derived growth factor
- IL
- interleukin
- VSMC
- vascular smooth muscle cell
- AP-1
- activator protein-1
- LTR
- long terminal repeat
- IRES
- internal ribosome entry site
- TNF
- tumor necrosis factor
- GAPDH
- glyceraldehyde-3-phosphate dehydrogenase
- ALU
- arbitrary light units
- CREB
- cAMP response element binding protein
- AP-1
- activation protein-1
- RPA
- ribonuclease protection assay
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- Received February 17, 1999.
- Accepted August 9, 2000.
- The American Society for Pharmacology and Experimental Therapeutics
