Vascular smooth muscle cell (SMC) differentiation is a very important process during vasculogenesis and angiogenesis, and it is recognized that alterations in SMC phenotype play a role in the progression of several prominent cardiovascular diseases including atherosclerosis, hypertension, and restenosis. The overall goal of the proposed studies is to identify the mechanisms by which environmental signals regulate SMC differentiation marker gene expression. Serum response factor (SRF) is the only transcription factor that has been shown to regulate all of the SMC differentiation marker genes. Since RhoA regulates SRF, and because RhoA activity is affected by many environmental cues (matrix, contractile agonists, growth factors, mechanical stretch) we hypothesize that Rho signaling is important for regulating SMC-specific transcription, and ultimately, SMC phenotype.
Our specific aims are as follows:
Aim 1 - to identify the Rho-dependent signaling pathways that contribute to the regulation of SMC-specific gene expression. We will measure Rho activation in SMC, and we will use dominant negative approaches to determine the extent to which Rho and Rho effectors contribute to the regulation of SMC-specific promoter/reporter constructs.
Aim 2 - to identify the mechanisms by which Rho affects SRF-dependent transcription in SMC. We will study the effects of Rho on the regulation of SRF phosphorylation and DNA binding, and on SRF's interaction with other transcription factors.
Aim 3 - to determine the effects of RhoA signaling on SMC differentiation in vivo. Because SMC phenotype is regulated by many diverse environmental cues that cannot be accurately reproduced in culture models, it is important to study SMC differentiation in vivo. We will express dominant negative and constitutively active forms of Rho specifically in SMC in mice using the SM myosin heavy chain promoter. Measuring SMC differentiation marker gene expression, examining vessel and organ morphology, and determining proliferation indices will assess effects on SMC differentiation. Completion of these aims should lead to a better understanding of the signaling and transcription mechanisms that regulate SMC differentiation and perhaps to novel targets for cardiovascular therapeutic intervention.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL070953-02
Application #
6633426
Study Section
Pathology A Study Section (PTHA)
Program Officer
Srinivas, Pothur R
Project Start
2002-06-01
Project End
2007-05-31
Budget Start
2003-06-01
Budget End
2004-05-31
Support Year
2
Fiscal Year
2003
Total Cost
$289,665
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Pathology
Type
Schools of Medicine
DUNS #
608195277
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
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Weise-Cross, Laura; Taylor, Joan M; Mack, Christopher P (2015) Inhibition of Diaphanous Formin Signaling In Vivo Impairs Cardiovascular Development and Alters Smooth Muscle Cell Phenotype. Arterioscler Thromb Vasc Biol 35:2374-83
Staus, Dean P; Weise-Cross, Laura; Mangum, Kevin D et al. (2014) Nuclear RhoA signaling regulates MRTF-dependent SMC-specific transcription. Am J Physiol Heart Circ Physiol 307:H379-90
Rozenberg, Julian M; Tesfu, Daniel B; Musunuri, Srilaxmi et al. (2014) DNA methylation of a GC repressor element in the smooth muscle myosin heavy chain promoter facilitates binding of the Notch-associated transcription factor, RBPJ/CSL1. Arterioscler Thromb Vasc Biol 34:2624-31
Bai, Xue; Lenhart, Kaitlin C; Bird, Kim E et al. (2013) The smooth muscle-selective RhoGAP GRAF3 is a critical regulator of vascular tone and hypertension. Nat Commun 4:2910
Medlin, Matt D; Taylor, Joan M; Mack, Christopher P (2012) Quantifying sphingosine-1-phosphate-dependent activation of the RhoGTPases. Methods Mol Biol 874:89-97
Staus, Dean P; Taylor, Joan M; Mack, Christopher P (2011) Enhancement of mDia2 activity by Rho-kinase-dependent phosphorylation of the diaphanous autoregulatory domain. Biochem J 439:57-65
Staus, Dean P; Blaker, Alicia L; Medlin, Matt D et al. (2011) Formin homology domain-containing protein 1 regulates smooth muscle cell phenotype. Arterioscler Thromb Vasc Biol 31:360-7
Doherty, Jason T; Lenhart, Kaitlin C; Cameron, Morgan V et al. (2011) Skeletal muscle differentiation and fusion are regulated by the BAR-containing Rho-GTPase-activating protein (Rho-GAP), GRAF1. J Biol Chem 286:25903-21
Mack, Christopher P (2011) Signaling mechanisms that regulate smooth muscle cell differentiation. Arterioscler Thromb Vasc Biol 31:1495-505

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