The capacity of vascular smooth muscle cells (SMCs) to modulate their response to arterial injury has been implicated in the pathogenesis of vascular proliferative syndromes including atherosclerosis and restenosis following coronary intervention. We have utilized the SMC-specific mouse SM22a promoter as a model system to elucidate the transcriptional programs that control VSMC development and differentiation. During the initial funding cycle of this award, the cis-acting elements and trans-acting factors that control expression of the SM22a promoter were defined. Two nuclear protein binding sites in the SM22a promoter (SME- 1 and SME-4) were identified which contain consensus CArU boxes that bind specifically to the MADS box transcription factor, SRF. Remarkably, a multimerized copy of either SME-l or SME-4 is necessary and sufficient to restrict activity of a LacZ reporter gene to arterial SMCs in transgenic mice. These data lead us to hypothesize that SRF, in concert with other potentially novel transcriptional activators (and potentially repressors), regulates SMC-specific gene expression and SMC phenotype. The overall goal of the proposed studies is to elucidate the molecular basis of SRF-dependent transcription in arterial SMCs.
The specific aims of these studies are to: i) Examine the molecular basis of SRF-CArG box activity in SMCs, ii) Examine protein-protein associations that modulate activity of the SM22a promoter in SMCs with particular attention on SRF/homeobox protein interactions, iii) Examine signaling pathways underlying LIMK- 1-mediated activation of the SM22cz promoter, and iv) Examine the capacity of SRF-/- ES cells to contribute to the SMC lineage(s) in SRF-/- -C57BL/6 chimenc mice and define downstream SMC and mesodermal genes regulated by SRF in the embryo. Taken together, these studies will elucidate the transcriptional program and an important signaling pathway that modulates expression of the SM22a gene in SMCs. Because CArG box-containing elements have been identified in multiple other SMC-specific genes these studies will provide fundamental insights into the molecular mechanisms that control SMC differentiation and the modulation of vascular SMC phenotype.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL056915-10
Application #
6857086
Study Section
Pathology A Study Section (PTHA)
Program Officer
Goldman, Stephen
Project Start
1997-04-01
Project End
2006-03-31
Budget Start
2005-04-01
Budget End
2006-03-31
Support Year
10
Fiscal Year
2005
Total Cost
$277,375
Indirect Cost
Name
University of Pennsylvania
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Li, Jian; Zhu, Xiaohong; Chen, Mary et al. (2005) Myocardin-related transcription factor B is required in cardiac neural crest for smooth muscle differentiation and cardiovascular development. Proc Natl Acad Sci U S A 102:8916-21
Abdullah, Ibrahim; Lepore, John J; Epstein, Jonathan A et al. (2005) MRL mice fail to heal the heart in response to ischemia-reperfusion injury. Wound Repair Regen 13:205-8
Lepore, John J; Cappola, Thomas P; Mericko, Patricia A et al. (2005) GATA-6 regulates genes promoting synthetic functions in vascular smooth muscle cells. Arterioscler Thromb Vasc Biol 25:309-14
Proweller, Aaron; Pear, Warren S; Parmacek, Michael S (2005) Notch signaling represses myocardin-induced smooth muscle cell differentiation. J Biol Chem 280:8994-9004
Ding, Rubai; Darland, Diane C; Parmacek, Michael S et al. (2004) Endothelial-mesenchymal interactions in vitro reveal molecular mechanisms of smooth muscle/pericyte differentiation. Stem Cells Dev 13:509-20
Du, Kevin L; Ip, Hon S; Li, Jian et al. (2003) Myocardin is a critical serum response factor cofactor in the transcriptional program regulating smooth muscle cell differentiation. Mol Cell Biol 23:2425-37
Kim, S; Lin, H; Barr, E et al. (1997) Transcriptional targeting of replication-defective adenovirus transgene expression to smooth muscle cells in vivo. J Clin Invest 100:1006-14
Kim, S; Ip, H S; Lu, M M et al. (1997) A serum response factor-dependent transcriptional regulatory program identifies distinct smooth muscle cell sublineages. Mol Cell Biol 17:2266-78