Intimal hyperplasia and/or constrictive remodeling are major causes of recurrent disease following vascular reconstruction. Transforming growth factor-beta (TGF- beta) is an important cytokine that has been found to be integrally ' involved in both of these processes. The goal of this proposal is to explore the role of TGF-beta signaling intermediates in the pathophysiology of intimal hyperplasia and constrictive remodeling. We will specifically examine a family of, intracellular signaling proteins, termed SMADs, and their role in these two processes. Our laboratory and others have shown that TGF-beta inhibits smooth muscle cell (SMC) proliferation and stimulates apoptosis; functions that would limit intimal hyperplasia. Conversely, TGF-beta stimulates extracellular matrix production (collagen I being the predominant I type), an effect that enhances the formation of hyperplastic lesions. In preliminary experiments, we have found that: Smads selectively mediate the effects of TGF-beta. Specifically, Smad3 stimulates collagen expression but has no effect on) SMC proliferation. These differential functions of Smad3 in SMCs may allow us to design molecular tools that can selectively preserve the """"""""inhibitory"""""""" effects but block the """"""""stimulatory"""""""" effects of TGF-beta on intimal hyperplasia. In the studies detailed in this proposal, we will further define the role of Smad3 and other Smad proteins in vascular SMC function.
In specific aim I we will evaluate the function of Smads in SMC by transiently transfecting wild type and dominant negative mutant Smads as well as reporter genes for SMC function into SMC lines. We will then create adenoviral vectors that express selected Smads that appear to have a significant impact on SMC physiology and test their effect in human primary vascular SMC.
In specific aim II, we will explore the interaction of TGF-beta with the promoter of the gene of type I collagen. The ultimate goal of these experiments will be to design an oligonucleotide decoy that can act as a selective genetic inhibitor of collagen transcription. Finally, in specific aim III we will test the hypothesis that stimulation and/or inhibition of Smads or selective inhibition of the collagen promoter can limit the formation of intimal hyperplasia in a rat model of vascular injury. We anticipate that the results of these studies will both enhance our knowledge of the pathophysiology of intimal hyperplasia and also allow for the design of novel therapies to inhibit this complex human disease process which affects thousands of patients each year.
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