Nuclear Factor-κB Activation in Diabetic Rat Kidney: Evidence for Involvement of P-Selectin in Diabetic Nephropathy

Abstract

Activation of a transcription factor, nuclear factor-κB (NF-κB), is a key step in the pathogenesis of diabetic nephropathy. In this study, we investigated the role of P-selectin, a platelet-derived adhesion molecule, in diabetic nephropathy by examining the activation status of NF-κB in the renal cortex of streptozotocin (STZ)-treated rats. The STZ treatment induced pathogenetic parameters such as increased creatinine clearance, increased blood glucose and massive albuminuria in a time-dependent manner. Electrophoretic mobility shift assays (EMSAs) with a specific probe, representing the P-selectin gene promoter, revealed the activation status of NF-κB in the STZ-treated rats, as judged by the time-dependent increase in the formation of the specific protein-DNA complexes. This increase was associated with the increased pathogenetic parameters. Supershift assays with specific antibodies revealed that p50, but not p52, p65, Rel B, or c-Rel, may be involved in the activation of NF-κB, though the component primarily responsible for the increase could not be determined. Western blot analysis confirmed an increase in P-selectin in STZ-treated rats. Notably, treatment with ammonium pyrrolidinedithiocarbamate, an antioxidant and inhibitor of NF-κB, inhibited the activation of NF-κB in STZ-treated rats and decreased P-selectin in the renal cortical tissue. Our results indicate that expression of the P-selectin gene is induced through the activation of NF-κB and that P-selectin may be involved in the pathogenesis of diabetic nephropathy.