ARE CELLS RESCUED FROM ‘LOW DENSITY DEATH’ BY CO-OPERATION BETWEEN PHOSPHOLIPASES C AND D?
✍ Scribed by Morten Rasmussen; Leif Rasmussen
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 76 KB
- Volume
- 24
- Category
- Article
- ISSN
- 1065-6995
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Cells of the ciliate Tetrahymena thermophila die when transferred at low density to a lipid‐free nutritionally complete medium. This death is prevented and they will start to proliferate if protein kinase C is activated and this activation is sustained. We propose that this takes place in two stages. Firstly, the phospholipase C pathway beginning with and specific for phosphatidylinositol leads to the formation of diacylglycerol and inositol tris ‐phosphate. Diacylglycerol activates protein kinase C, and inositol tris ‐phosphate via Ca^2+^phospholipase D (PLD). Secondly, the protein kinase C response can now be sustained by diacylglycerol produced by phospholipase D, using phosphatidylcholine and phosphatidylserine as substrates. Should this switching from PI‐specific phospholipase C (PLC) to phospholipase D fail, then the cell will die in the course of milliseconds during the minutes following inoculation.