During the previous funding cycles of this grant, we showed that 1. Activation of calcineurin-NFAT signaling is required for both receptor tyrosine kinase (RTK) and G protein-coupled receptor (GPCR) agonist-induced vascular smooth muscle cell (VSMC) growth and motility. 2. Blockade of calcineurin-NFAT activation signaling inhibits balloon injury-induced neointima formation. 3. Cyclins such as cyclin D1 and cyclin A2 and pro- inflammatory cytokines such as IL-6 appear to be the NFAT-target genes in mediating RTK and GPCR agonist-induced VSMC growth and motility and injury-induced vascular wall remodeling. 4. NFAT, particularly NFTAc1, also modulates monocyte chemoattractant protein-1 (MCP-1), a potent chemokine-induced human aortic smooth muscle cell (HASMC) growth and motility as well as vascular wall remodeling via cyclin D1- dependent PKN1 and PAK1 activation. Having observed a common role for NFATc1 in vascular wall remodeling in response to various cues, we have decided to identify additional effector molecules of this transcriptional factor and therefore performed a microarray analysis. The microarray analysis identified LIM and cysteine-rich domains 1 (LMCD1)/Dyxin as a highly responsive gene to thrombin and its expression was dependent on NFAT activation. When we searched for its function, we found that it is a transcriptional cofactor and represses GATA6 and promotes cardiac hypertrophy. With these clues in mind, we examined for its function in HASMCs. Surprisingly, we found that LMCD1 plays a role in thrombin-induced migration and proliferation of HASMCs. In addition, we discovered that LMCD1 is required for CDC6 and IL-33 expression. CDC6 is a member of pre-replicative complex (pre-RC) and is essential in loading mini chromosome maintenance (MCM) proteins onto DNA for initiation of replication whereas IL-33 is a pro-inflammatory cytokine. What is more exciting is that LMCD1 interacts with E2F1 and regulates CDC6 and IL-33 expression in response to thrombin. Furthermore, we found that whereas CDC6 expression is required for HASMC replication IL-33 is needed for their motility. Based on these novel discoveries and preliminary findings, we hypothesize that LMCD1 is a target gene of NFATc1 and LMCD1 by modulating CDC6 and IL-33 expression plays an essential role in vascular wall remodeling. To address this major hypothesis, we will test the following three specific aims. SA1: LMCD1 expression by PLC?3-dependent NFATc1 activation is essential for neointima formation. SA2: LMCD1 in combination with E2F1 modulates the pre-RC regulator CDC6 expression in vascular wall remodeling. SA3: LMCD1 in combination with E2F1 enhances the expression of IL-33 in vascular wall remodeling. The observations of the proposed experiments will identify LMCD1 as a master mediator of restenosis and therefore could become a novel target for drug development in controlling this vascular response following angioplasty and stent implantation.
Restenosis is a major complication after percutaneous transluminal coronary angioplasty. The experiments of this proposal will identify LMCD1 as a master mediator of restenosis and therefore could be a novel target for the drug development in suppressing the risk of developing restenosis following angioplasty and stent implantation.
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