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[MAP kinase cascade in cultured rat mesangial cells]
T Sugimoto1, R Kikkawa, M Haneda
1Third Department of Medicine, Shiga University of Medical Science, Japan.
Abstract:
In order to evaluate the intracellular signaling pathway of endothelin 1 (ET-1), we examined mitogen-activated protein kinase (MAPK) cascade in cultured rat glomerular mesangial cells. Treatment of quiescent mesangial cells with ET-1 increased kinase activities toward bovine myelin basic protein (MBP). Maximal activation was at 10 min and ED50 was about 5 nM. The 44- and 42-kDa kinases were activated in MBP containing gel kinase assay. These kinases were identified as extracellular signal regulated kinase (ERK) 1 and ERK2 with immunoblotting, respectively. MAPK or ERK kinase (MEK), one of the MAPK kinases, was present in rat mesangial cells and ET-1 also activated this MAPK kinase. These results indicate that MAPK kinase and MAP kinase are rapidly activated by ET-1 and may modulate cellular functions in rat mesangial cells.
Insights
Endothelin 1 (ET-1) rapidly activates the mitogen-activated protein kinase (MAPK) cascade, including MAPK kinase (MEK) and extracellular signal-regulated kinases (ERK) 1 and 2, in rat mesangial cells, suggesting a role in cellular function.
Area of Science:
- Cellular biology
- Molecular biology
- Renal physiology
Background:
- Endothelin 1 (ET-1) is a potent vasoconstrictor peptide.
- Its role in intracellular signaling pathways within renal cells requires further elucidation.
- Glomerular mesangial cells play a crucial role in kidney function.
Purpose of the Study:
- To investigate the intracellular signaling pathway activated by ET-1 in cultured rat glomerular mesangial cells.
- To determine the involvement of the mitogen-activated protein kinase (MAPK) cascade in ET-1 signaling.
- To identify specific MAPK components activated by ET-1.
Main Methods:
- Cultured rat glomerular mesangial cells were treated with ET-1.
- Kinase activities were assessed using myelin basic protein (MBP) as a substrate.
- Mitogen-activated protein kinases (MAPKs) and MAPK kinases (MEKs) were identified via immunoblotting and gel kinase assays.
Main Results:
- ET-1 treatment significantly increased kinase activities in mesangial cells, with maximal activation at 10 minutes.
- The 44-kDa and 42-kDa kinases, identified as extracellular signal-regulated kinase (ERK) 1 and ERK2, were activated.
- ET-1 also activated MAPK kinase (MEK) in these cells.
Conclusions:
- ET-1 rapidly activates the MAPK cascade, including MEK and ERK1/2, in rat glomerular mesangial cells.
- This activation suggests that the MAPK pathway is a key mediator of ET-1's effects on mesangial cell function.
- Further research is warranted to understand the specific cellular functions modulated by this pathway.