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Epidermal growth factor enhances glomerular mesangial cell soluble phospholipase A2 activity
J V Bonventre1, J H Gronich, R A Nemenoff
1Medical Services, Massachusetts General Hospital, Boston.
The Journal of Biological Chemistry
|March 25, 1990
Summary
Epidermal growth factor (EGF) activates phospholipase A2 (PLA2) in kidney cells, independent of protein kinase C. This finding reveals a novel regulatory pathway for PLA2 in renal mesangial cells.
Area of Science:
- Cell Biology
- Biochemistry
- Renal Physiology
Background:
- Soluble phospholipase A2 (PLA2) is hormonally regulated in cultured renal mesangial cells.
- Epidermal growth factor (EGF) is investigated for its effect on PLA2 regulation.
Purpose of the Study:
- To characterize the mechanisms regulating PLA2 activity in renal mesangial cells using EGF.
- To determine if EGF activates PLA2 directly and to elucidate the signaling pathways involved.
Main Methods:
- Assessing PLA2 activity in cell extracts after EGF stimulation.
- Using phorbol myristate acetate (PMA) and 1-oleoyl-2-acetylglycerol as activators.
- Employing Mono-Q anion exchange chromatography for enzyme fractionation.
- Investigating the role of protein kinase C, cAMP, and G proteins via specific modulators.
Main Results:
- EGF directly enhanced PLA2 activity in cell-free extracts.
- PMA also enhanced PLA2 activity, with both agonists acting on the same enzyme form.
- EGF-induced PLA2 activation was independent of protein kinase C down-regulation.
- Neither cAMP nor pertussis toxin affected EGF-induced PLA2 enhancement.
Conclusions:
- EGF induces a stable modification of PLA2 activity in glomerular mesangial cells.
- The EGF-mediated PLA2 activation is independent of polyphosphoinositide hydrolysis and protein kinase C signaling.
- This study reveals a novel EGF-driven regulatory mechanism for PLA2 in renal cells.