Alterations in the differentiated state of the smooth muscle cell (SMC) play a key role in the development and progression of a variety of cardiovascular diseases. The long-term goal of this project is to elucidate cellular and molecular mechanisms that control the growth and differentiation of SMC during vascular development, and how these control processes are altered during phenotypic switching of SMC in association with vascular injury and disease. Results of our recent studies have implicated the fascinating pluripotency gene Krupple-Like Factor 4 (KLF4) as a key mediator of SMC phenotypic switching in cultured SMC, and in vivo following carotid ligation injury in conditional KLF4 knockout (KO) mice generated in our lab. Studies in this proposal will test the hypothesis that KLF4 plays a critical role in regulating transitions in the differentiated state of vascular SMC during development, as well as during phenotypic switching following vascular injury or development of atherosclerosis.
Aim 1 will determine mechanisms by which KLF4 represses expression of SMC marker genes in vivo with vascular injury including determining if KLF4 mediates repression SMC genes by: a) binding to conserved G/C repressor and/or TCE elements found in most SMC promoters;b) inducing epigenetic modifications associated with transcriptional silencing;c) suppressing expression of the potent SMC-selective SRF co-activator myocardin;and/or d) inducing pluripotency genes.
Aim 2 will test the hypothesis that delayed repression of SMC marker genes and exacerbated lesion formation following vascular injury observed in our previous studies in conditional KLF4 knockout mice, were mediated, at least in part, by loss of KLF4 in SMC rather than its loss in EC or macrophages. Studies will include bone marrow transfer, and SMC specific conditional KLF4 KO studies in mice injury.
Aim 3 is to determine if conditional or SMC specific conditional knockout of KLF4 alters atherosclerotic intimal lesion size or cellular composition in ApoE knockout mice.
Aim 4 is to determine the role of KLF4 in activation of genes such as MMP3, MCP-1, iNOS, and VCAM-1 which are likely to play an important functional role in intimal lesion development and/or progression in response to vascular injury or experimental atherosclerosis.

Public Health Relevance

Abnormal control of the differentiated state (i.e. cell specific properties) of vascular smooth muscle cells (SMC) is known to play a critical role in a number of major diseases including atherosclerosis, asthma, hypertension, and tumor metastasis. Studies in this proposal will provide novel insights into mechanisms that control SMC differentiation in development and disease and may lead to new and more effective therapies.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Atherosclerosis and Inflammation of the Cardiovascular System Study Section (AICS)
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Olive, Michelle
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University of Virginia
Schools of Medicine
United States
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Starke, Robert M; Chalouhi, Nohra; Jabbour, Pascal M et al. (2014) Critical role of TNF-? in cerebral aneurysm formation and progression to rupture. J Neuroinflammation 11:77
Ali, Muhammad S; Starke, Robert M; Jabbour, Pascal M et al. (2013) TNF-? induces phenotypic modulation in cerebral vascular smooth muscle cells: implications for cerebral aneurysm pathology. J Cereb Blood Flow Metab 33:1564-73
Starke, Robert M; Ali, Muhammad S; Jabbour, Pascal M et al. (2013) Cigarette smoke modulates vascular smooth muscle phenotype: implications for carotid and cerebrovascular disease. PLoS One 8:e71954
Gomez, Delphine; Shankman, Laura S; Nguyen, Anh T et al. (2013) Detection of histone modifications at specific gene loci in single cells in histological sections. Nat Methods 10:171-7
Murgai, Meera; Thomas, James; Cherepanova, Olga et al. (2013) Xenotropic MLV envelope proteins induce tumor cells to secrete factors that promote the formation of immature blood vessels. Retrovirology 10:34
Gomez, Delphine; Owens, Gary K (2012) Smooth muscle cell phenotypic switching in atherosclerosis. Cardiovasc Res 95:156-64
Hoofnagle, Mark H; Neppl, Ronald L; Berzin, Erica L et al. (2011) Myocardin is differentially required for the development of smooth muscle cells and cardiomyocytes. Am J Physiol Heart Circ Physiol 300:H1707-21