AR & AGE-RAGE IN AGING: IMPACT ON ENDOTHELIAL AND VASCULAR STRESS

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Aging in human subjects is accompanied by the inevitable development of cardiovascular and endothelial dysfunction, which, over time, especially as co-incident and superimposed aging-related disorders mount, leads to a heightened vulnerability to ischemia/reperfusion (I/R) stress. In response to the critique, we have developed and focused this project on two key components of aging cardiovasculature that prime the aged organism for amplified injury, both innately, and upon I/R. These studies are tightly coupled to Projects 1 & 2 of this Program. First, basal degrees of inflammation increase in aged vasculature, particularly in aged endothelial cells (EC). Second, innate cardiomyocyte dysfunction develops in aging. Mitochondria become defective in cardiomyocytes as they age and increase generation of reactive oxygen species (ROS), thereby impairing ATP generation. Such fundamental injury phenomena promote conditions for enhanced cell death - especially in I/R. Thus, in both EC and cardiomyocytes retrieved from aged animals, identification of the precise signal transduction and transcriptional regulation mechanisms underlying these findings is essential in identifying novel targets to suppress adverse cardiovascular aging and diminish the amplified vulnerability to I/R stress. We will probe the hypothesis that increased activity of the polyol enzyme AR in aging drives mechanisms that enhance generation of AGE, thereby recruiting RAGE and consequent signal transduction in EC and cardiomyocytes; mechanisms which we predict are linked to cardiovascular dysfunction. We propose that when aged organisms are exposed to superimposed I/R stress in the heart, increased AR and AGE-RAGE signaling amplify production of inflammatory and stress mediators that exaggerate injury in the aged heart. In a manner highly synergistic with Projects 1&2 (intact heart), isolated EC and cardiomyocytes from aged animals will be used to probe the signal transduction and transcription factor mechanisms that regulate basal and I/R stress in the aged heart. Project 3 shares mouse/rat models with Projects 1 and 2. Project 3 will utilize all three Cores of the Program Project during all five years of the grant.