Microvascular hyperpermeability represents an important injurious process underlying the development ofmany inflammatory diseases including diabetic complications. The long-term goal of our research program isto understand the cellular and molecular mechanisms in the regulation of microvascular barrier functionunder physiological and pathological conditions. As an integral component of the program, this project isdesigned to elucidate the signaling pathways and molecular mechanisms responsible for microvascularhyperpermeability during development of diabetes, a disease that affects a large population with highmorbidity and mortality resulting from complications characterized by microvascular injury. Our centralhypothesis states that diabetes upregulates PKCbeta in microvascular endothelium at multiple levels viaMAPK-stimulated gene expression, PDK1-potentiated catalytic activity, and DAG-mediated kinase activation.We further propose that upregulated PKCbeta increases the paracellular permeability of venular endotheliumby inducing endothelial cell contraction via the GDI-RhoA-ROCK cascade coupled with intercellular junctiondisorganization triggered by beta-catenin phosphorylation and VE-cadherin dissociation.
Three specific aims are proposed: 1) to unequivocally establish the role of PKCbeta in microvascular leakage during diabetes; 2)to characterize the signaling mechanisms of PKCbeta upregulation in diabetic pigs; and 3) to elucidate themolecular basis of PKCbeta-elicited microvascular hyperpermeability.
These aims will be accomplishedthrough a multifaceted molecular physiology approach that incorporates molecular techniques with functionalanalyses at the microvascular level. A human-relevant pig model of diabetes will serve as the primary modelfor quantitative assessment of endothelial barrier function in intact microvessels. Data derived from this studywill provide new insights into the pathogenesis of diabetic microvascular complications. Identification of theprecise molecular mechanisms responsible for PKC-induced end-point injury may lead to a new avenue forsearching therapeutic targets. Based on this study, a future direction of our research efforts will be directedto the development of molecular probes and therapies for diagnosis and treatment of microvascular leakageassociated with chronic inflammatory diseases.
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