Although it is clear that diabetic patients are at increased risk for vascular complications, the molecular basis of this potentiated process of macrovascular lesion formation remains to be further elucidated. The central hypothesis poses that the process of occlusive macrovascular lesion formation in diabetes is potentiated by the anti-apoptotic effect of hyperglycemia and enhanced glucose metabolism on vascular smooth muscle cell (VSMC) fate. In accord with this postulate, the preliminary data in cultured VSMC indicate that elevated levels of ambient glucose inhibit VSMC suicide. Moreover, the investigators have observed that VSMC apoptosis during vascular remodeling is markedly attenuated within the vessels of diabetic animals compared to normoglycemic controls. These findings suggest a close interrelationship between VSMC glucose metabolism, the regulation of apoptosis and the pathogenesis of macrovascular disease. Based on the preliminary observations, the investigators have formulated a working model in which postulates that increased glucose metabolism induced by the hyperglycemia state and facilitated by up-regulated expression of glucose transporters promotes VSMC survival by stimulating an anti-apoptotic signaling pathway mediated by protein kinase C, extracellular signal-regulated kinase (ERK). Furthermore, the investigators hypothesize that this protein kinase signaling cascade regulates VSMC fate by modulating the expression and activity of the anti-apoptotic gene Bcl-xL. The experimental approach will employ both pharmacologic probes and genetic engineering techniques to dissect the cellular signaling events those couple changes in glucose metabolism to the regulation of VSMC death. The investigators anticipate that the creation of novel genetically engineered mice with selective alterations in vascular glucose metabolism will provide further evidence for the molecular mechanisms by which hyperglycemia potentiates macrovascular lesion formation. Specifically they will: I. Define the effect of alterations in glucose metabolism on the regulation of VSMC apoptosis. II. Define the essential role of the PKC-ERK-Bcl-xL signaling pathway in mediating the anti- apoptotic effect of increased glucose metabolism on VSMC fate. III. Characterize the anti-apoptotic effect of hyperglycemia on the process of vascular remodeling and lesion formation in the intact animals.
