Interfering RNA against PKC-α inhibits TNF-α-induced IP3R1 expression and improves glomerular filtration rate in rats with fulminant hepatic failure

Abstract

We have reported that tumor necrosis factor-α (TNF-α) is critical for reduction of glomerular filtration rate (GFR) in rats with fulminant hepatic failure (FHF). The present study aims to evaluate the underlying mechanisms of decreased GFR during acute hepatic failure. Rats with FHF induced by d-galactosamine plus lipopolysaccharide (GalN/LPS) were injected intravenously with recombinant lentivirus harboring short hairpin RNA against the protein kinase C-α ( PKC-α) gene (Lenti-shRNA-PKC-α). GFR, serum levels of aminotransferases, creatinine, urea nitrogen, potassium, sodium, chloride, TNF-α, and endothelin-1 (ET-1), as well as type 1 inositol 1,4,5-trisphosphate receptor (IP₃R1) expression in renal tissue were assessed. The effects of PKC-α silencing on TNF-α-induced IP₃R1, specificity protein 1 (SP-1), and c-Jun NH₂-terminal kinase (JNK) expression, as well as cytosolic calcium content were determined in glomerular mesangial cell (GMCs) with RNAi against PKC-α. Renal IP₃R1 overexpression was abrogated by pre-treatment with Lenti-shRNA-PKC-α. The PKC-α silence significantly improved the compromised GFR, reduced Cr levels, and reversed the decrease in glomerular inulin space and the increase in glomerular calcium content in GalN/LPS-exposed rats. TNF-α treatment increased expression of PKC-α, IP₃R1, specificity protein 1 (SP-1), JNK, and p-JNK in GMCs and increased Ca^{2 +} release and binding activity of SP-1 to the IP₃R1 promoter. These effects were blocked by transfection of siRNA against the PKC-α gene, and the PKC-α gene silence also restored cytosolic Ca²⁺ concentration. RNAi targeting PKC-α inhibited TNF-α-induced IP₃R1 overexpression and in turn improved compromised GFR in the development of acute kidney injury during FHF in rats.

Keywords: acute kidney failure; fulminant hepatic failure; protein kinase C-α; tumor necrosis factor-α; type 1 inositol 1,4,5-trisphosphate receptor.