Cardiovascular disease is by far the largest cause of morbidity and mortality in the elderly population. Compelling evidence indicates that age-related changes in vascular repair cells are a root cause of the increased incidence of atherosclerosis in the elderly. It is thought that a 'failure to die'by vascular repair cells leads to their accumulation in the vessel wall after injury by smoking, hypertension, and hyperlipidemia. We have documented functional resistance to apoptotic factors in cells derived from human atherosclerotic lesions, and in cells derived from aged Fisher 344 rats. In this proposal for an extension of the MERIT Award, we show that a combination of cell biology and microarray profiling has likely identified the underlying cause of this defect. Microarray profiling of human lesion cells, drug-treated cells, and aged rodent arteries and cells produced a list of candidate genes which could confer resistance to apoptosis. In systematic analysis of these targets by QPCR, Western Blot, and forced overexpression, we could determine that Bcl-XI remains a strong candidate for a causative factor in age-related resistance to apoptosis induced by fas ligation. Likewise, cyclin D1 and Smurf2 remain solid candidates as mediators of the resistance to TGF-fi>. In the second term of the MERIT Award, we continue toward the goal of understanding the specific mechanisms that control apoptotic resistance in vascular cells.
Three Specific Aims are proposed: 1) further confirm these targets by siRNA inhibition to restore function, and by forced overexpressionto induce the phenotype in sensitive cells; 2) define the entire pathway of resistance using microarrays and proteomic methods to find components that are amenable to intervention; 3) determine the effect of modulating the resistance pathway on the course of injury-induced lesion formation in the aging rodent vessel wall. The studies have already identified novel therapeutic agents, such as flavopiridol and picetannol, a natural grape product, that are capable of modulating resistance to apoptosis in the lesion. The results of the proposed studies will precisely define the mechanism, and identify other steps that are amenable to intervention. The goal of these studies is to identify both diagnositic markers of advancing atherosclerotic lesions as well as targets which can be modulated by Pharmaceuticalsor genetic interventions to prevent the accumulation of cells in the vessel wall, and thereby prevent heart attacks and stroke.
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