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Ceramide inhibits phospholipase D in a cell-free system
M E Venable1, A Bielawska, L M Obeid
1Departments of Medicine and Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
The Journal of Biological Chemistry
|October 4, 1996
Summary
Ceramide inhibits phospholipase D (PLD) activation in HL-60 cells, specifically interfering with protein kinase C (PKC)-mediated signaling pathways. This finding highlights ceramide
Area of Science:
- Cellular biology
- Biochemistry
- Signal transduction
Background:
- Phospholipase D (PLD) plays a crucial role in cellular signaling.
- Ceramide has been recently implicated in the regulation of PLD activity.
Purpose of the Study:
- To investigate the role of ceramide in regulating phospholipase D (PLD) activation.
- To elucidate the mechanism by which ceramide affects PLD activity, particularly in relation to protein kinase C (PKC).
Main Methods:
- Experiments were conducted using intact HL-60 cells and a cell-free system.
- PLD activation was measured by the conversion of labeled phosphatidylcholine.
- Phorbol myristate acetate (PMA) and guanosine 5'-O-(3-thiotriphosphate (GTPgammaS) were used to activate PLD.
- The effects of C6-ceramide and its structural analogs were assessed.
Main Results:
- C6-ceramide inhibited PMA-induced PLD activation in intact cells but did not affect PKC translocation.
- In a cell-free system, ceramide did not inhibit GTPgammaS-induced PLD activation.
- Ceramide specifically inhibited the synergistic activation of PLD by GTPgammaS and PKC activators.
- Recombinant ARF and PKCalpha-mediated PLD activation was inhibited by C6-ceramide.
Conclusions:
- Ceramide interferes with the protein kinase C (PKC)-mediated activation of phospholipase D (PLD).
- The inhibitory effect of ceramide on PLD activation is upstream of direct PLD activation by GTPgammaS.