Propranolol increases phosphatidic acid level via activation of phospholipase D.
OBJECTIVE
To investigate the propranolol-induced phospholipase D (PLD) activity, its contribution to the increase in the level of phosphatidic acid, and the role of protein kinase C (PKC) in this event.


METHODS
A combination of [3H]-myristate labeling, transphosphatidylation reaction, lipid extraction, and thin layer chromatography was used to measure the PLD activity. PKC inhibitors and prolonged phorbol-12-myristate-13-acetate (PMA) treatment were used to study the involvement of PKC in propranolol-induced PLD activation. Immunoblotting was used to detect the intracellular levels of PKC.


RESULTS
Treatment of A-549 cells with propranolol in the presence of butanol, resulted in the rapid activation of PLD. Propranolol induced the formation of phosphatidylbutanol (PBut), a unique product of PLD, at the expense of phosphatidic acid (PA) formation. Pretreatment of cells with PKC inhibitors Ro-31-8220, staurosporine, and rottlerin increased the propranolol-induced PLD. Down-regulation of PKC by prolonged treatment of cells with PMA also potentiated the propranolol-induced PLD activity.


CONCLUSIONS
Propranolol induces rapid activation of PLD activity, which results in the increase in intracellular level of PA. The data also indicate that propranolol-induced PLD activity could be negatively regulated by PKC.
Chai
M Q
MQ
State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Chen
J S
JS
Zhao
S
S
Song
J G
JG
D004789:Enzyme Activation; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology; D010712:Phosphatidic Acids / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism*; D011433:Propranolol / Q000494:pharmacology*; D011493:Protein Kinase C / Q000502:physiology; D019311:Staurosporine / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D010712:Phosphatidic Acids; D011433:Propranolol; D011493:Protein Kinase C; D010739:Phospholipase D; D019311:Staurosporine