Vascular smooth muscle cells are a vital component of the blood vessel wall, possessing extraordinaryadaptive abilities. These cells display a range of phenotypes that are dependent upon the selective utilizationof transcriptional programs. While smooth muscle modulation is essential for normal blood vessel function,their adaptive abilities are adversely associated with the pathologies of vascular occlusion diseases.Consequently, the molecular mechanisms governing gene transcription leading to resultant phenotypes areboth biologically and clinically relevant. As an inroad to elucidating critical features that control smoothmuscle transcription, our studies are focused on the development and differentiation of precursor cells intomature smooth muscle. Differentiation is accompanied by the orchestrated activation of a precise set ofgenes required for contraction. Though definitive regulatory elements, and corresponding transcriptionfactors are recognized to have a role in differentiation, how they are coupled to signals that convey selectivegene expression is not well understood. We hypothesize that extracellular signals, like transforming growthfactor-beta (TGF-IS), use a distinct combination of intracellular pathways and transcription factors to impartsmooth muscle-restricted expression. TGF-li has emerged as primary candidate for governing smoothmuscle cell phenotypes.
The aims of this proposal are designed to employ the smooth muscle-specificexpression of the cysteine-rich protein 1 (CRP1) gene to investigate the cis-acting elements, and trans-acting factors that convey selective transcriptional activity in response to defined signaling events. We haveidentified a unique regulatory region of the CRP1 gene that drives expression exclusively in arterial smoothmuscle cells. We intend to use this regulatory element to characterize essential transcriptional pathwaysimportant for the expression of the CRP1 gene in differentiated smooth muscle cells.
The specific aims are:1) To define the transcriptional mechanisms underlying the activation of the CRP1 gene by transforminggrowth factor-beta-1 (TOF-I^). 2) To determine the relationship between the functional activity of serumresponse factor (SRF), and signaling events that govern smooth muscle gene expression. 3) Tounequivocally determine the necessity of the CArG element for expression of CRP1 by targetedmutagenesis. These studies are significant, as they will extend beyond the analysis of the transcriptionalregulators, and determine the exact pathways that mediate transactivation, to address fundamentalquestions regarding the manifestation of smooth muscle cell phenotypes.
