While many different curative approaches are being tested, gene therapy represents a significant hope for treatment and prevention of atherosclerosis and other proliferative diseases of the vasculature, since it can be made highly cell-specific, can mimic or restore normal in vivo function, and can be permanent or transient depending on vector design. The ultimate goal of their study is to design more effective gene therapy vectors for use in the vasculature by understanding the molecular mechanisms by which DNA and DNA-protein complexes are actively transported into the nucleus. Currently, a number of gene delivery systems for use in the arterial wall are being studied, but as yet their low efficiency of gene transfer and lack of cell-specific targeting and expression are major limitations. Dean and Zimmer have identified a DNA sequence that increases nuclear localization uniquely in smooth muscle cells, a critical target in vascular gene therapy. Continued studies will lead to cell-selective vectors that will inhibit vascular smooth muscle proliferation and the ensuing disease states.
Import occurs through the nuclear pore complex in the absence of mitosis, and is sequence-specific.
They hypothesize that nuclear import is mediated by sequences containing binding sites for eukaryotic transcription factors and they have shown that such proteins are required for nuclear import of DNA in an in vitro system. Moreover, the cell-selective nuclear import of the SMGA promoter is most likely mediated by transcription factors that are expressed exclusively in smooth muscle cells. The grant is designed to test the models for plasmid nuclear import and will lead to the creation of new vascular gene therapy vectors that are both cell-specific and capable of greater gene transfer efficiencies. Specifically, the exact DNA sequences that promote nuclear import will be characterized as will the proteins that bind to them and the mechanisms of nuclear import will be elucidated using an in vitro system.