Role of proNGF/p75NTR in diabetes-induced barrier dysfunction

Breakdown of the inner blood-retinal barrier (BRB) leads to macular edema, a major cause of blindness in diabetes. Because current treatments are invasive with considerable side effects, novel molecular targets for effective drug treatments are needed. My overall goal is to understand the pathogenesis of diabetes-induced endothelial dysfunction in an effort to identify new therapeutic targets. My long-term goal is to have a career as an independent research scientist studying vascular complications of diabetes. Previously, our lab has shown that diabetes hampers maturation of nerve growth factor (NGF) resulting in accumulation of its precursor, proNGF, and its receptor p75NTR. These changes are associated with neuronal death, glial inflammation, and vascular injury, however, the role of proNGF and p75NTR in diabetes-induced endothelial barrier dysfunction is unknown. The central hypothesis of this proposal is that diabetes-induced proNGF stimulates p75NTR dependent activation of RhoA leading to endothelial barrier dysfunction. Barrier dysfunction is characterized by increased vascular permeability, actin cytoskeleton rearrangements, and alterations in tight junction protein expression. Two specific aims are proposed. In aim one, we show that both proNGF and p75NTR are required for diabetes-induced BRB breakdown in diabetic wild-type mice, endothelial specific p75NTR knockout mice, and human retinal endothelial (HRE) cells. In aim two, we test the hypothesis that proNGF stimulated cleavage of p75NTR is an essential step in RhoA activation and subsequent barrier dysfunction. Successful completion of the proposed studies will elucidate the novel role of proNGF in stimulating p75NTR-dependent BRB breakdown and will identify new therapeutic targets for restoring endothelial barrier function. (AHA Program: Postdoctoral Fellowship)