The Cyclosporin A-sensitive Nuclear Factor of Activated T Cells (NFAT) Proteins Are Expressed in Vascular Smooth Muscle Cells
DIFFERENTIAL LOCALIZATION OF NFAT ISOFORMS AND INDUCTION OF NFAT-MEDIATED TRANSCRIPTION BY PHOSPHOLIPASE C-COUPLED CELL SURFACE RECEPTORS*
- From the Department of Pharmacology, Emory University School of Medicine, and the §Graduate Program in Molecular Therapeutics and Toxicology, Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, Georgia 30322
Abstract
Expression of the antigen-regulated, cyclosporin A-sensitive nuclear factor of activated T cells (NFAT) is not restricted to lymphoid cells, as thought initially, but the physiological inducers of NFAT-mediated transcription in non-lymphoid cells are unknown. Here, cultured vascular smooth muscle cells (VSMC) are shown to express two isoforms of the NFAT family endogenously, which are localized differentially in cells under resting conditions. Using a retroviral NFAT-specific luciferase reporter, we show that VSMC support previously unrecognized complexities in NFAT-mediated transcription, including evidence for negative regulation by Ca2+ signaling and positive regulation through co-activation of adenylyl cyclase and Ca2+ mobilization. The VSMC mitogen platelet derived growth factor-BB (PDGF-BB) induces NFAT-mediated transcription in VSMC. Thrombin and angiotensin II, which activate Gαq-coupled receptors, are significantly weaker inducers of NFAT-mediated luciferase expression than is PDGF-BB. However, co-stimulation studies show that Gαq receptor agonists augment the NFAT-mediated transcriptional response to PDGF-BB. This synergy can be explained in part by augmented intracellular Ca2+ transients elicited by multiple agonist challenges. These data indicate that agonists for phospholipase C-coupled receptors stimulate NFAT-mediated transcription in VSMC differentially, and that NFAT can function to integrate co-activating signals in the extracellular environment.
Footnotes
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↵* This work was supported in part by National Institutes of Health Grants HL52801, AR42687, AR43410, and DE11987 and by a grant-in-aid from the American Heart Association and Sanofi-Winthrop.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵‡ These authors contributed equally to this work.
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↵¶ Established Investigator of the American Heart Association. To whom correspondence should be addressed: Dept. of Pharmacology, Emory University School of Medicine, Rm. 5031, O. W. Rollins Research Bldg., Atlanta, GA 30322. Tel.: 404-727-2467; Fax: 404-727-0365; E-mail: medtjm{at}bimcore.emory.edu.
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↵1 The abbreviations used are: NFAT, nuclear factor of activated T cells; PLC, phospholipase C; CsA, cyclosporin A; VSMC, vascular smooth muscle cells; PMA, phorbol myristate acetate; PDGF-BB, platelet-derived growth factor BB chain; IL-2, the cytokine interleukin-2; HRP, horseradish peroxidase; PKA, protein kinase A; NFRE, NFAT response element; CREB, cAMP response element-binding protein; ATF, activating transcription factor; HBSS, Hank’s balanced salt solution; BSA, bovine serum albumin; DMEM, Dulbecco’s modified Eagle’s medium; PBS, phosphate-buffered saline; LTR, long terminal repeat; GM, growth medium.
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- Received March 24, 1998.
- Revision received May 20, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
