Reactive oxygen species (ROS), endothelial injury and macrophages play critical roles in ischemia/reperfusion (I/R) kidney injury. Our data show stanniocalcin-1 (STC1) diminishes superoxide generation in macrophages, through induction of uncoupling protein-2 (UCP2), decreases the response of macrophages to chemoattractants- and migration across an endothelial monolayer. In cultured endothelial cells, STC1 preserve barrier function. STC1: diminishes superoxide generation; inhibits cytokine-induced activation of Jun-N- terminal kinase (JNK) and loss of tight junction proteins expression. STC1 transgenic mice, which exhibit elevated serum levels and preferential expression of STC1 in macrophages and endothelium, display resistance to I/R kidney injury. Overall hypothesis: STC1 protects from I/R kidney injury through: suppression of superoxide generation; maintenance of normal endothelial barrier function following I/R kidney injury; and inhibition of macrophages. In Objective I, we will determine the role of superoxide and Daxx in STC1-mediated inhibition of JNK in endothelial cells. In Objective II, we will determine the effect of STC1 on hypoxia/reoxygenation (H/RO)-induced changes in the expression and assembly of tight junction proteins in cultured primary kidney endothelial cells. In the context of I/R kidney injury, Objective III will examine endothelial leakage to macromolecules, kidney inflammation and function after kidney endothelium-specific or macrophage-specific overexpression or deletion of STC1. Few therapeutic options are currently available for acute kidney injury (AKI). Our data identify STC1 as a potential therapeutic target for ischemic injury in the kidney and other organs, and our proposed studies will further elucidate STC1 mechanisms of action.
The development of kidney failure is associated with high rate of complications and death, and the options for treatment are limited. Our results show that mice engineered to produce large amounts of stanniocalcin-1 protein are resistant to insults that normally cause kidney failure. We plan to study how stanniocalcin-1 protects from kidney failure, and our proposed experiments could lead to new therapies for this costly disease.
