The Of P38mapk Mechanism In Diabetic Nephropathy Study

Objective : To investigate the relationship between p38 mitogen-activated protein kinase (p38 MAPK) and nuclear factor-к B (NF-кB), peroxisome proliferator-activated receptor-γ (PPAR-γ), matrix metalloproteinase-9 (MMP-9), monocyte chemoattractant protein-1 (MCP-1), cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF), in order to study the effect of p38 MAPK on diabetic nephropathy. Methods: We mimiced diabetic state in vitro using high glucose, high insulin, H2O2 and advanced glycosylation end products (AGEs) to stimulate rat glomerular mesangial cells (RGMC) separately, the protein expression of phospho-p38 MAPK, NF-кB and COX-2 was detected by Western blot technique, the mRNA expression of MCP-1, COX-2, PPAR-γ and MMP-9 was analysed by RT-PCR , the protein expression and location of VEGF was detected by immunohistochemistry assay. After RGMC were pre-treated with SB203580 (p38 MAPK special inhibitor), the cells were incubated with above stimulating factors, the expression of NF-кB, PPAR-γ, MMP-9, MCP-1, COX-2 and VEGF was measured separately. Results : High glucose, high insulin, H2O2 and AGE could significantly activate p38 MAPK respectively, the protein expression of phosphor-p38 MAPK increased significantly in RGMC. Simultaneously, the expression of NF-кB, MCP-1, COX-2 and VEGF was significantly increased, while the expression of PPAR-γ and MMP-9 was significantly decreased in RGMC. The expression of COX-2, MCP-1, NF-кB and VEGF was markedly decreased, and the expression of PPAR-γ and MMP-9 was markedly increased after RGMC were pre-treated with SB203580 and incubated by above 4 stimulating factors. Conclusion: p38 MAPK was upstream signaling molecule of MCP-1, COX-2, and VEGF. p38MAPK may activate NF-κB and antagonize PPAR-γ and MMP-9. p38 MAPK might be one of very important starting factors in the development of diabetic nephropathy. ART TWO THE EFFECT OF SODIUM SELENITE ON THE EXPRESSION OF p38 MAPK IN RAT GLOMERULAR MESANGIAL CELLS ABSTRACT Objective:To investigate the effect of sodium selenite on the expression of p38 mitogen-activated protein kinase (p38 MAPK) in rat glomerular mesangial cells (RGMC), in order to study the effectmechanism of selenium on diabetic nephropathy. Methods:RGMC were incubated with high glucose, high insulin, H₂O₂ and advanced glycosylation end products (AGE) respectively; simultaneously, RGMC pre-treated with sodium selenite were also incubated with above stimulating factors, the expression of phospho-p38 MAPK, nuclear factor-к B (NF-кB), peroxisome proliferator-activated receptor-γ (PPAR-γ), matrix metalloproteinase-9 (MMP-9) , monocyte chemoattractant protein-1(MCP-1), cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) was detected by Western blot, RT-PCR and immunohistochemistry assay. Results:Sodium selenite significantly represses the expression of phospho-p38 MAPK induced by above 4 stimulating factors; the expression of NF-кB, MCP-1, COX-2 and VEGF was significantly inhibited and the expression of PPAR-γ and MMP-9 was significantly increased by sodium selenite. Conclusion:Sodium selenite has the similar effect to SB203580. It may reduce the expression of COX-2, MCP-1, NF-кB and VEGF,and increase the expression of PPAR-γ and MMP-9 by suppressing p38 MAPK signaling pathway. And sodium selenite has the similar effect to the agonist of PPAR-γ, which enhances the sensitivity to insulin and then reduces the proliferation of MC. Selenium may be operative drugs in preventing from the development of diabetic nephropathy.