NFAT Transcription in Vascular Smooth Muscle

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DESCRIPTION (provided by the applicant): The immunosuppressants cyclosporin A (CsA) and FK506 cause a spectrum of serious side effects, including impaired cardiovascular function. This is not only a serious clinical problem, but also indicates that cellular processes affected by immunosuppressant are crucial for the maintenance of normal cardiovascular homeostasis. Through binding to either of two distinct cellular adapters, both drugs inhibit the phosphatase calcineurin. A family of transcription factors termed the nuclear factors of activated T-cells (NFAT) are well-known calcineurin substrates. Although initially considered T-cell restricted, studies indicate that NFAT isoforms are widely distributed in non-lymphoid tissues throughout the body. The applicant has published several studies supporting the general notion that NFAT can serve as a transcriptional effector for signaling evoked by various hormones, autacoids and growth factors within subsets of vascular smooth muscle and endothelial cells. We speculate that NFAT participates in the modulation of vascular gene expression programs elicited by such physiological agonists and that interference with NFAT mediated transcription may contribute to immunosuppressant drug toxicity. If so, on balance, NFAT likely serves as a key regulator of important homeostatic processes, and its targets would be of great interest to discover. General objectives of this project include deriving a better understanding of how NFAT mediated transcription operates in a vasculature smooth muscle cell context, and what genes it may be involved in regulating. To explore this, we will assess whether four distinct NFAT isoforms are differentially regulated and drive unique patterns of vascular gene expression. Since no NFAT gene targets in smooth muscle cells have been definitively described, we will carry forward studies that strongly support the hypothesis that NFATs trans-activate the COX-2 and IL-6 genes within VSMC. We will also study how co-activation of cAMP-dependent kinase pathways modulate NFAT transcription. Lastly, we will examine the physiologic consequences of disrupted NFAT function by studying how CsA treatment and NFAT gene ablation influence vascular function using murine models. The project will exploit innovative and powerful recombinant gene expression techniques in cultured cell models, coupled with state-of-the-art physiological assessments. Our expected findings are likely to provide important new insights into the role of NFAT in vascular smooth muscle and its relationship to immunosuppressant-induced vascular dysfunction.