The overall aim of this proposal is to determine the mechanisms by which calcium (Ca) signaling differentially regulates vascular smooth muscle cell (SMC) phenotype. SMC phenotypic modulation is characterized by alterations in SMC differentiation marker gene expression (SMGX) including SM cr-actin, smooth muscle myosin heavy chain (SMMHC) and SM22a. Transcriptional regulation of SM a-actin, SMMHC, and SM22a is regulated in part through the transcription factor SRF (serum response factor) binding to CArG c/s regulatory promoter elements. Multiple SRF-CArG-dependent signaling pathways have been described in regulating SMC phenotypic modulation during development, in mature contractile SMCs and in vascular disease (i.e. atherosclerosis. However, although Ca has connections to virtually every biological process in nature, including SMC contraction, it is still unclear what role Ca plays in regulating SMGX and SMC phenotypic modulation. We recently showed in adult SMCs that Ca influx via L-type voltage-gated Ca channels (VGCC) resulted in an increase in SMGX through mechanisms that are dependent on RhoA/Rho-kinase, myocardin (a SMC-selective SRF co-factor) and increased binding of SRF to CArG cis promoter regulatory elements required for SMGX. Exciting recent studies from our lab provide evidence showing that the contractile agonist sphingosine-1-phosphate increases SMGX in part via VGCCs/Rho-kinase/SRF and selective S1P receptor subtypes. However, sphingosine-1-phosphate, not VGCC activation alone, also mediates SMGX through calcineurin and enrichment of NFAT2, a Ca-activated transcription factor, within CArG promoter elements of intact chromatin. Taken together, the preceding studies clearly implicate a role for differential regulation of SMGX by sphingosine-1-phosphate- and depolarization-dependent Ca signaling. Thus, Aim 1 will determine molecular mechanisms by which Ca differentially regulates SMGX in adult SMCs. Our hypothesis is that sphingosine-1-phosphate and depolarization-induced Ca influx regulate SRF-dependent SMGX through RhoA/Rho-kinase/myocardin but differentially regulate the interaction of Ca-activated transcription factors mediated by calcineurin/NFAT signaling pathways and by inducing changes in chromatin structure that enhance binding of SRF to CArG elements.
Aim 2 will determine the role of Ca-dependent signaling on differentiation, maturation and function of SMCs derived from embryonic stem cells. We will employ embryonic stem cells genetically null for select genes (defined in Aim 1) to determine the role of these factors in regulating SMC differentiation/maturation/function in the embryoid body model of SMC differentiation.
Aim 3 will determine the role of Ca signaling pathways in SMC phenotypic modulation associated with vascular injury using SMC-selective Cre/lox technology. The overall hypothesis is that Ca-dependent molecular mechanisms regulate SMGX during SMC development and maintenance of the contractile phenotype, and that these control mechanisms are altered during phenotypic modulation associated with atherosclerosis.
|Halterman, Julia A; Kwon, H Moo; Wamhoff, Brian R (2012) Tonicity-independent regulation of the osmosensitive transcription factor TonEBP (NFAT5). Am J Physiol Cell Physiol 302:C1-8|
|Halterman, Julia A; Kwon, H Moo; Zargham, Ramin et al. (2011) Nuclear factor of activated T cells 5 regulates vascular smooth muscle cell phenotypic modulation. Arterioscler Thromb Vasc Biol 31:2287-96|
|Lee, Monica Y; Garvey, Sean M; Ripley, Marcia L et al. (2011) Genome-wide microarray analyses identify the protein C receptor as a novel calcineurin/nuclear factor of activated T cells-dependent gene in vascular smooth muscle cell phenotypic modulation. Arterioscler Thromb Vasc Biol 31:2665-75|
|Gelfand, Bradley D; Meller, Julia; Pryor, Andrew W et al. (2011) Hemodynamic activation of beta-catenin and T-cell-specific transcription factor signaling in vascular endothelium regulates fibronectin expression. Arterioscler Thromb Vasc Biol 31:1625-33|
|Nilsson-Berglund, Lisa M; Zetterqvist, Anna V; Nilsson-Ohman, Jenny et al. (2010) Nuclear factor of activated T cells regulates osteopontin expression in arterial smooth muscle in response to diabetes-induced hyperglycemia. Arterioscler Thromb Vasc Biol 30:218-24|
|Lee, Monica Y; Garvey, Sean M; Baras, Alex S et al. (2010) Integrative genomics identifies DSCR1 (RCAN1) as a novel NFAT-dependent mediator of phenotypic modulation in vascular smooth muscle cells. Hum Mol Genet 19:468-79|
|Mathews, Thomas P; Kennedy, Andrew J; Kharel, Yugesh et al. (2010) Discovery, biological evaluation, and structure-activity relationship of amidine based sphingosine kinase inhibitors. J Med Chem 53:2766-78|
|Orr, Anthony Wayne; Hastings, Nicole E; Blackman, Brett R et al. (2010) Complex regulation and function of the inflammatory smooth muscle cell phenotype in atherosclerosis. J Vasc Res 47:168-80|
|Garvey, Sean M; Sinden, Daniel S; Schoppee Bortz, Pamela D et al. (2010) Cyclosporine up-regulates Krüppel-like factor-4 (KLF4) in vascular smooth muscle cells and drives phenotypic modulation in vivo. J Pharmacol Exp Ther 333:34-42|
|Hastings, Nicole E; Feaver, Ryan E; Lee, Monica Y et al. (2009) Human IL-8 regulates smooth muscle cell VCAM-1 expression in response to endothelial cells exposed to atheroprone flow. Arterioscler Thromb Vasc Biol 29:725-31|
Showing the most recent 10 out of 14 publications