Protein kinase Czeta regulates phospholipase D activity in rat-1 fibroblasts expressing the alpha1A adrenergic receptor.
BACKGROUND
Phenylephrine (PHE), an alpha1 adrenergic receptor agonist, increases phospholipase D (PLD) activity, independent of classical and novel protein kinase C (PKC) isoforms, in rat-1 fibroblasts expressing alpha1A adrenergic receptors. The aim of this study was to determine the contribution of atypical PKCzeta to PLD activation in response to PHE in these cells.


RESULTS
PHE stimulated a PLD activity as demonstrated by phosphatidylethanol production. PHE increased PKCzeta translocation to the particulate cell fraction in parallel with a time-dependent decrease in its activity. PKCzeta activity was reduced at 2 and 5 min and returned to a sub-basal level within 10-15 min. Ectopic expression of kinase-dead PKCzeta, but not constitutively active PKCzeta, potentiated PLD activation elicited by PHE. A cell-permeable pseudosubstrate inhibitor of PKCzeta reduced basal PKCzeta activity and abolished PHE-induced PLD activation.


CONCLUSIONS
alpha1A adrenergic receptor stimulation promotes the activation of a PLD activity by a mechanism dependent on PKCzeta; Our data also suggest that catalytic activation of PKCzeta is not required for PLD stimulation.
Parmentier
Jean-Hugues
JH
Department of Pharmacology and Center for Connective Tissue Diseases and Vascular Biology, College of Medicine, The University of Tennessee Health Science Center, 874 Union Avenue, Memphis, TN 38163, USA. jparmentier@utmem.edu
Gandhi
Gautam K
GK
Wiggins
Monique T
MT
Saeed
Abdelwahab E
AE
Bourgoin
Sylvain G
SG
Malik
Kafait U
KU
D058646:Adrenergic alpha-1 Receptor Agonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D015870:Gene Expression; D010656:Phenylephrine / Q000494:pharmacology; D010739:Phospholipase D / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000235:genetics / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D000099221:Protein Kinase C zeta
D058646:Adrenergic alpha-1 Receptor Agonists; D000316:Adrenergic alpha-Agonists; D004791:Enzyme Inhibitors; D010656:Phenylephrine; D010739:Phospholipase D; D011493:Protein Kinase C; D018340:Receptors, Adrenergic, alpha-1; D013755:Tetradecanoylphorbol Acetate; D000099221:Protein Kinase C zeta; C547715:Adra1a protein, rat