Molecular Medicine Selective Modulation of Nuclear Factor of Activated T-Cell Function in Restenosis by a Potent Bipartite Peptide Inhibitor

Rationale: Nuclear factor of activated T-cells (NFAT) is importantly implicated in pathological cardiac remod-eling and vascular lesion formation. NFAT functionality is mainly regulated by calcineurin, a Ca 2؉-dependent multi-effector phosphatase. Calcineurin inhibitors such as cyclosporine A (CsA) were shown to be effective in the treatment of restenosis and vascular inflammation but with adverse side effects. Objective: This prompted the design of more selective inhibitors such as VIVIT and inhibitors of NFAT-calcineurin association, which unfortunately have a poor potency precluding clinical use. Conclusions: We designed a bipartite NFAT inhibitor that is more potent than VIVIT and more selective than CsA. MCV1 constitutes not only a powerful tool to unravel NFAT function but also a potential drug candidate for the treatment of diseases implicating NFAT activation. T ranscription factors of the nuclear factor of activated T-cells (NFAT; C1–C5) family are expressed in T-cells, B-cells, NK-cells, and mast cells, as well as in all major nonimmune cell types relevant to cardiovascular diseases, including cardiomyocytes, vascular smooth muscle cells (VSMCs), endothelial cells, and macrophages. 1 NFAT func-tionality is tightly regulated by calcineurin, a calmodulin-dependent calcium-activated phosphatase. On activation, cal-cineurin binds and dephosphorylates cytoplasmic NFAT, which then translocates to the nucleus of activated cells to induce cytokine expression. Except for its key role in immunity , NFAT has been importantly implicated in osteoclast differentiation, muscle fiber-type specialization, cardiac valve development, myocardial hypertrophy, heart failure, and restenosis. 1–9 Given the key role of calcineurin–NFAT signaling in various physiological and immunologic processes, its inhibition has long been considered a powerful therapeutic modality in the treatment of graft transplant rejection, autoimmune diseases, and cardiovascular disorders. The traditional immunosuppressants cyclosporine A (CsA) and FK506 disrupt calcineurin phosphatase activity to inhibit all of its downstream effectors, including NFAT. However, their application was associated with adverse side effects such as nephrotoxicity, hypertension, and malignancy. 10 –12 In search of more selective and less toxic NFAT inhibitors, recent attention has been given to calcineurin–NFAT docking inhibitors that block calcineurin–NFAT interactions rather than phosphatase activity of calcineurin. These efforts were given further impetus to the identification of VIVIT peptide (MAGPHPVIVITGPHEE), 13 LxVP peptide, 14,15 and a series of synthetic leads, termed inhibitors of NFAT– calcineurin association (INCA). 16 However, the low potency of VIVIT (Ϸ30 –100 ␮mol/L in vascular cells 17), the cytotoxicity of INCA compounds, or the broad inhibition of calcineurin phos-phatase activity by LxVP peptide 13,16,18 disqualifies these compounds for direct …