Related Experiment Videos
Interaction of MAPK and 12-lipoxygenase pathways in growth and matrix protein expression in mesangial cells
Marpadga A Reddy1, Sharon G Adler, Young-Sook Kim
1Department of Diabetes, Beckman Research Institute of the City of Hope, Duarte California 91010, USA.
Abstract:
The lipoxygenase (LO) pathway of arachidonate metabolism and mitogen-activated protein kinases (MAPKs) can mediate cellular growth and ANG II effects in vascular smooth muscle cells. However, their role in renal mesangial cells (MC) is not very clear. ANG II treatment of rat MC significantly increased 12-LO mRNA expression and formation of the 12-LO product 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE; P < 0.03]. ANG II-induced [(3)H]leucine incorporation was blocked by an LO inhibitor, cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate (P < 0.02). 12(S)-HETE and ANG II directly induced cellular hypertrophy and fibronectin (FN) expression (P < 0.01) to a similar extent. ANG II and 12(S)-HETE led to activation of p38(MAPK) and its target transcription factor cAMP-responsive element-binding protein (CREB). ANG II- and 12(S)-HETE-induced CREB activation and [(3)H]leucine incorporation were blocked by the p38(MAPK) inhibitor SB-202190. A specific molecular inhibitor of rat 12-LO mRNA, namely, a novel ribozyme, could attenuate ANG II-induced FN mRNA. Thus p38(MAPK)-dependent CREB activation may mediate ANG II- and LO product-induced FN expression and cellular growth in rat MC. ANG II effects may be mediated by the LO pathway. These results suggest a novel interaction between LO and p38(MAPK) activation in MC matrix synthesis associated with renal complications.
Insights
Angiotensin II (ANG II) activates the lipoxygenase (LO) pathway and p38 mitogen-activated protein kinase (MAPK) in renal mesangial cells, promoting cellular growth and fibronectin expression, potentially contributing to kidney complications.
Area of Science:
- Cell Biology
- Renal Physiology
- Molecular Medicine
Background:
- The lipoxygenase (LO) pathway and mitogen-activated protein kinases (MAPKs) influence cellular growth and Angiotensin II (ANG II) effects in vascular smooth muscle cells.
- The specific roles of these pathways in renal mesangial cells (MC) remain less understood.
Purpose of the Study:
- To investigate the involvement of the LO pathway and p38 MAPK in ANG II-induced cellular responses within rat MC.
- To elucidate the molecular mechanisms linking ANG II, LO products, and cellular matrix synthesis in MC.
Main Methods:
- Treatment of rat MC with ANG II and its inhibitors.
- Measurement of 12-LO mRNA expression and 12(S)-HETE production.
- Assessment of [(3)H]leucine incorporation and fibronectin (FN) expression.
- Analysis of p38 MAPK and CREB activation using specific inhibitors and a ribozyme.
Main Results:
- ANG II significantly increased 12-LO mRNA and 12(S)-HETE production in rat MC.
- Both ANG II and 12(S)-HETE induced cellular hypertrophy and fibronectin expression.
- ANG II and 12(S)-HETE activated p38 MAPK and CREB; inhibition blocked protein synthesis and FN expression.
- A ribozyme targeting 12-LO mRNA attenuated ANG II-induced FN mRNA.
Conclusions:
- The LO pathway and p38 MAPK activation mediate ANG II-induced cellular growth and fibronectin expression in rat MC.
- p38 MAPK-dependent CREB activation is a key mechanism in ANG II and LO product-induced matrix synthesis.
- These findings suggest a novel interaction between LO and p38 MAPK in MC matrix synthesis relevant to renal complications.