MG132 reduces the pro-inflammatory effect of cyclooxygenase 2 (COX-2) on glomerular mesangial cells

Cyclooxygenase 2 (COX-2) over expression is involved in the proliferation of mesangial cells in the pathogenesis of glomerulonephritis, and nuclear factor kappa B (NF-κB) signaling participates in the induction of COX-2 gene expression in these cells. This study explores the effect of MG132, a NF-κB proteasome inhibitor, on the pro-inflammatory effect of glomerular COX-2 gene overexpression. A COX-2-overexpressing (COX-2+) mesangial cell line was established in this study. The expression of chemokine (C-C motif) ligand 2 (CCL2) and NF-κB were determined by quantitative real-time polymerase chain reaction (qRT-PCR). The activation of NF-κB was detected by electrophoretic mobility shift assay (EMSA), and the transcriptional activity of NF-kB was determined by luciferase-based reporter gene assay. CCL2 expression in NF-κB-activated cells was suppressed by MG132 (P < 0.05), especially in NF-κB-activated COX-2+ cells. The binding of NF-κB to DNA increased in MG132-treated cells and was accompanied by an increase in NF-κB p50 and p65 subunits. The transcriptional activity of NF-κB in MG132-treated cells significantly decreased, especially in COX-2+ cells (P < 0.05). Therefore, MG132 could reduce pro-inflammatory effects in glomerular mesangial cells with COX-2 gene overexpression and suppress the CCL2 expression by interfering with the dismantling of nuclear NF-κB p65.   Key words: Nuclear factor kappa B (NF-κB) inhibitor, MG132, proteasome inhibitor, cyclooxygenase 2, glomerulonephritis.