Regulation of phospholipase D activity in neuroblastoma cells.
The regulation of phospholipase D was studied in human neuroblastoma cells using phosphatidylethanol as a marker of the enzyme activity. Carbachol induced phospholipase D activity in SH-SY5Y cells. Muscarinic antagonists inhibited the response with potencies suggesting that muscarinic M1 receptors are responsible for the activation. In permeabilized SH-SY5Y cells, both the carbachol- and GTP gamma S-induced Peth formation was inhibited by GDP beta S, indicating that both responses are mediated via a G-protein. The protein kinase C inhibitors, bisindolylmaleimide and staurosporine significantly inhibited the carbachol-induced Peth formation whereas H7 had no effect. Thus, the cholinergic activation of phospholipase D in SH-SY5Y cells is probably mediated via a direct receptor-G-protein coupling but an involvement of protein kinase C cannot be excluded. Calmidazolium, a calmodulin antagonist, induced an increase in phosphatidylethanol formation in both SH-SY5Y and IMR-32 cells. This effect was inhibited by genistein and tyrphostin, indicating a tyrosine kinase dependent pathway for phospholipase D activation in neuroblastoma cells.
Department of Medical Neurochemistry, Lund University Hospital, Sweden.
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L
Gustavsson
M C
MC
Boyano-Adánez
C
C
Larsson
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S
Aradottir
C
C
Lundqvist
D006801:Humans; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009447:Neuroblastoma / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014407:Tumor Cells, Cultured
D018727:Muscarinic Antagonists; D011976:Receptors, Muscarinic; D010739:Phospholipase D