Phospholipase D activity in PC12 cells. Effects of overexpression of alpha2A-adrenergic receptors.
PC12 neuronal cells express a membrane phospholipase D (PLD) activity that is detected at similar levels in undifferentiated or differentiated cells. The regulation of this activity by agonists was explored. Membrane phospholipase D activity was increased by treatment of cells with the phorbol ester phorbol 12-myristate 13-acetate (PMA) or with nerve growth factor. The ability of PMA to activate PLD was confirmed in intact PC12 cells. Basal activity of PLD in membranes was reduced in RG20, a PC12 cell line overexpressing the human alpha2A-adrenergic receptor. PMA did not increase PLD activity in RG20 cells, as assessed both in membrane preparations and in intact cells. Cyclic AMP levels did not regulate phospholipase D activity in either cell type. However, incubation of RG20 cells with the alpha2-adrenergic antagonist rauwolscine or with pertussis toxin increased membrane PLD activity and restored activation of PLD by PMA. These data suggest that the effects of the overexpressed alpha2A-adrenergic receptor on PLD activity are mediated by precoupling of the receptor to the heterotrimeric GTP-binding protein, Gi, but are independent of adenylate cyclase regulation. The results of this study suggest that membrane phospholipase D activity can be negatively regulated via Gi in PC12 cells.
Ella
K M
KM
Department of Cell and Molecular Pharmacology, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
Qi
C
C
McNair
A F
AF
Park
J H
JH
Wisehart-Johnson
A E
AE
Meier
K E
KE
D000818:Animals; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D009414:Nerve Growth Factors / Q000494:pharmacology; D016716:PC12 Cells / Q000201:enzymology*; D010739:Phospholipase D / Q000032:analysis* / Q000378:metabolism; D051381:Rats; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D009414:Nerve Growth Factors; D018341:Receptors, Adrenergic, alpha-2; D010739:Phospholipase D; D013755:Tetradecanoylphorbol Acetate