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Complement C5b-9 activates cytosolic phospholipase A2 in glomerular epithelial cells
A V Cybulsky1, J C Monge, J Papillon
1Department of Medicine, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada.
The American Journal of Physiology
|November 1, 1995
Summary
Complement C5b-9 activates cytosolic phospholipase A2 (cPLA2) in rat glomerular epithelial cells (GEC), increasing arachidonic acid release and enhancing cell injury. This pathway may contribute to membranous nephropathy.
Area of Science:
- Cell Biology
- Immunology
- Nephrology
Background:
- Complement C5b-9 causes glomerular epithelial cell (GEC) injury and proteinuria in rat membranous nephropathy.
- Sublytic C5b-9 activates plasma membranes, releasing arachidonic acid (AA) and eicosanoids in cultured rat GEC.
Purpose of the Study:
- To investigate the role of phospholipase A2 (PLA2) in C5b-9-induced GEC injury.
- To identify the specific PLA2 isoform involved and its regulatory pathway.
Main Methods:
- Cultured rat GEC were treated with sublytic C5b-9.
- PLA2 activity was measured in cell lysates.
- GEC were transfected to overexpress cytosolic PLA2 (cPLA2).
- Arachidonic acid and prostaglandin E2 production were quantified.
- Cell viability and cytotoxicity assays were performed.
Main Results:
- Sublytic C5b-9 increased cytosolic PLA2 (cPLA2) activity in GEC, an effect blocked by protein kinase C inhibitors.
- C5b-9 did not affect other PLA2 activities.
- Overexpression of cPLA2 enhanced C5b-9-induced AA and prostaglandin E2 production.
- GEC overexpressing cPLA2 showed increased susceptibility to C5b-9-induced cytotoxicity.
Conclusions:
- C5b-9 activates cPLA2, likely through phosphorylation via a protein kinase C-dependent pathway.
- Activated cPLA2 promotes GEC injury by increasing substrate for eicosanoid synthesis.
- This cPLA2-mediated pathway contributes to glomerular damage in membranous nephropathy.