The fully differentiated vascular smooth muscle cell (SMC) is endowed with a genetic program of growth cessation and cell-restricted gene expression, the encoded proteins of which coordinate the unique contractile physiology of this muscle type. The functional role of one such protein, smooth muscle calponin (SM-CALP), has received considerable attention as an important modulator of SMC contraction and cellular growth. Moreover, like many SMC differentiation genes, SM-CALP expression is attenuated in vascular disease states (e.g., atherosclerosis), thus altering normal homeostasis within the vessel wall. While its physiology has been studied extensively, little information exists pertaining to the transcriptional control of SM-CALP. Understanding the transcriptional regulation of SM-CALP will be of vital importance in defining the basic molecular mechanisms that underlie both normal SMC physiology and the altered function of these cells in disease settings. Recently, a CArG box element residing in the 5' promoter of several SMC-restricted genes has been implicated in SMC-specific gene expression. However, transgenic studies point to more complex modes of muscle gene regulation that include the participation of regulatory elements residing great distances from the core promoter sequence. This application will test the thesis that SM-CALP expression multiple regulatory elements, including those far removed from the core promoter, that are functionally inactivated in the context of vascular disease. Proposed studies will examine the potential role of an intronic CArG box on SM-CALP promoter activity using cells and transgenic mice. Further studies will use innovative """"""""genome tools"""""""" to identify regulatory elements that may reside long distances from the core promoter. Such elements will then be tested in an in vivo model of vascular stenosis using an adenoviral-mediated reporter gene transfer method. These studies will contribute significantly to our understanding of the transcriptional control of SM-CALP during normal development and diseases, especially those of the vasculature. Such information will facilitate the design and implementation of potentially novel molecular interventions for the treatment of vascular disease.
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