? Glucotoxicity, lipotoxicity, advanced glycation end products (AGE), and reactive oxygen species (ROS) have emerged as important mediators of diabetes-induced tissue injury. However, the precise cellular targets and molecular mechanisms by which these mediators cause cellular injury in the kidney remain poorly defined. ? Both, glomerular (podocytes) and tubular epithelial cells are now emerging as important targets for diabetes-induced injury in diabetic nephropathy (DN). Thus, podocyte depletion has been described recently in humans with type 1 (T1DM) and type 2 (T2DM) diabetes, and is considered a strong predictor for the development of proteinuria. In addition, tubular epithelial apoptosis and epithelial-mesenchymal transition (EMT) may underlie the initiation of tubulointerstitial progression of DN. ? We present preliminary results that provide a compelling rationale to focus our research program on investigating the emerging role and mechanisms of epithelial cell injury in DN. Specifically, we will test two novel hypotheses: 1. The peroxisomal membrane proteins Mpv17l and/or Mpv17 are essential regulators of antioxidant defenses in glomerular podocytes and protect against diabetes-induced podocyte apoptosis and podocyte depletion (Bottinger, Mount Sinai); and 2. CD36 scavenger receptor for AGE and/or FFA is an essential mediator of AGE and/or FFA-induced tubular epithelial injury/apoptosis and tubulointerstitial progression of DN (Susztak, AECOM). ? The Specific Aims of this proposal are to test: ? 1. whether peroxisomal membrane proteins regulate antioxidant defense mechanisms in podocytes, and protect against ROS-mediated podocyte injury/apoptosis induced by diabetes ? 2. whether Mpv17-deficiency accelerates and increases podocyte apoptosis and depletion leading to progressive glomerulosclerosis and/or nodules in diabetic mouse models ? 3. which CD36-dependent intracellular pathways signal AGE and FFA induced tubular epithelial injury/apoptosis ? 4. whether proximal tubular overexpression of AGE binding proteins CD36 and RAGE leads to increased tubular epithelial injury/apoptosis and tubulointerstitial progression of DN in mice ? ? ?
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