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Involvement of p38 mitogen-activated protein kinase in PLL-AGE-induced cyclooxgenase-2 expression
Chien-Huang Lin1, Chih-Hsiung Wu, Wai-Yee Thum
1Graduate Institute of Biomedical Technology and School of Medical Technology, 250, Wu-Hsing Street, 110, Taipei, Taiwan.
Abstract:
In the present study, murine RAW 264.7 macrophages were incubated with poly-L-lysine-derived advanced glycosylation end products (PLL-AGEs) to examine cyclooxygenase-2 protein expression. Treatment of RAW 264.7 cells with PLL-AGEs caused the dose-dependent expression of cylooxygenase-2 but not cylooxygenase-1 and an increase in cylooxygenase activity. Increased cylooxygenase-2 expression was seen at 6 h and reached a maximum at 24 h. The tyrosine kinase inhibitor, genistein, and the p38 mitogen-activated protein kinase (MAPK) inhibitor, [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole] (SB 203580), inhibited PLL-AGE-induced cylooxygenase-2 expression, while the Ras inhibitor, FPT inhibitor II, and the MAP kinase kinase inhibitor, (2'-amino-3'-methoxyflavone) (PD 98059), had no effect on PLL-AGE-induced cylooxygenase-2 expression. Incubation of RAW 264.7 cells with PLL-AGEs resulted in activation of p38 MAPK, and this activation was suppressed by genistein and SB 203580. Taken together, our results suggest that activation of protein tyrosine kinase and p38 MAPK is involved in AGE-induced cyclooxygenase-2 expression in RAW 264.7 macrophages.
Insights
Advanced glycosylation end products (AGEs) induce cyclooxygenase-2 (COX-2) expression in macrophages. This process involves protein tyrosine kinase and p38 MAPK activation, highlighting a key inflammatory pathway.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Advanced glycosylation end products (AGEs) are implicated in various inflammatory conditions.
- Macrophage activation plays a crucial role in the inflammatory response.
- Cyclooxygenase-2 (COX-2) is a key enzyme in inflammation.
Purpose of the Study:
- To investigate the effect of poly-L-lysine-derived AGEs (PLL-AGEs) on cyclooxygenase-2 (COX-2) expression in RAW 264.7 macrophages.
- To elucidate the signaling pathways involved in PLL-AGE-induced COX-2 expression.
Main Methods:
- RAW 264.7 macrophages were treated with varying concentrations of PLL-AGEs.
- COX-2 protein expression and activity were measured.
- Inhibitors of specific signaling pathways (tyrosine kinase, p38 MAPK, Ras, MEK) were used to assess their effects on COX-2 expression.
- Activation of p38 MAPK was analyzed.
Main Results:
- PLL-AGEs induced a dose-dependent increase in COX-2 expression and activity in RAW 264.7 cells.
- COX-2 expression was upregulated at 6 hours, peaking at 24 hours.
- Inhibition of protein tyrosine kinase (genistein) and p38 MAPK (SB 203580) suppressed PLL-AGE-induced COX-2 expression.
- PLL-AGEs activated p38 MAPK, an effect blocked by genistein and SB 203580.
- Ras and MEK pathways were not involved in this process.
Conclusions:
- AGEs stimulate COX-2 expression in macrophages via protein tyrosine kinase and p38 MAPK signaling.
- This study identifies a specific molecular mechanism underlying AGE-induced inflammation in macrophages.
- Targeting these pathways could offer therapeutic strategies for AGE-related inflammatory diseases.