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Cell swelling activates phospholipase A2 in Ehrlich ascites tumor cells
S M Thoroed1, L Lauritzen, I H Lambert
1August Krogh Institute, University of Copenhagen, Denmark.
The Journal of Membrane Biology
|November 14, 1997
Summary
Cell swelling activates phospholipase A2, a key enzyme in cellular responses. This activation is crucial for the volume regulatory response in Ehrlich cells, involving G-protein signaling.
Area of Science:
- Biochemistry
- Cell Biology
- Oncology
Background:
- Ehrlich ascites tumor cells are a model for studying cellular responses to osmotic stress.
- Cell swelling triggers complex signaling pathways to restore cell volume.
Purpose of the Study:
- To investigate the role of phospholipases in the arachidonic acid release during cell swelling.
- To identify the specific phospholipase involved in the volume regulatory response of Ehrlich cells.
Main Methods:
- Ehrlich ascites tumor cells were loaded with radiolabeled fatty acids (arachidonic acid and stearic acid).
- Cells were exposed to hypotonic media, and the release of labeled fatty acids and production of lysophosphatidylcholine were measured.
- Inhibitors of phospholipase C (U7312) and phospholipase A2 (AACOCF3), as well as GDP beta S, were used to probe signaling pathways.
Main Results:
- Hypotonic stress significantly increased the release of 3H-labeled arachidonic acid and the production of 14C-stearic acid-labeled lysophosphatidylcholine.
- These effects were inhibited by AACOCF3 and GDP beta S, implicating a G-protein coupled activation of phospholipase A2.
- Involvement of phospholipase A1, C, and D was excluded.
Conclusions:
- Cell swelling activates phospholipase A2, likely the 85 kDa cytosolic type, through a partly G-protein coupled mechanism.
- This activation is essential for the volume regulatory response in Ehrlich ascites tumor cells.