The role of cytosolic Ca2+, protein kinase C, and protein kinase A in hormonal stimulation of phospholipase D in rat hepatocytes
| Autor: | M E Torres-Marquez, Jan B. Hoek, Lena Gustavsson, Gisela Moehren, Christine Benistant, Raphael Rubin |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
Male
Bisindolylmaleimide Vasopressins Phosphatidic Acids Glycerophospholipids Biology Biochemistry Piperazines Rats Sprague-Dawley chemistry.chemical_compound Alkaloids Ethers Cyclic 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine Ca2+/calmodulin-dependent protein kinase Okadaic Acid Phospholipase D Animals Protein kinase A Molecular Biology Protein Kinase C Protein kinase C Terpenes Cell Biology Isoquinolines Staurosporine Cyclic AMP-Dependent Protein Kinases Molecular biology Rats Enzyme Activation enzymes and coenzymes (carbohydrates) Cytosol Calphostin C Liver chemistry Tetradecanoylphorbol Acetate Thapsigargin Calcium lipids (amino acids peptides and proteins) Phosphatidylethanol |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 0021-9258 |
| DOI: | 10.1016/s0021-9258(17)42190-9 |
| Popis: | Ca(2+)-dependent and protein kinase C-dependent mechanisms of phospholipase D (PLD) activation were studied in rat hepatocytes by measuring phosphatidylethanol (Peth) formation in the presence of ethanol. Stimulation of Peth formation by 12-O-tetradecanoyl-phorbol 13-acetate (TPA), vasopressin, or A23187 was inhibited by multiple protein kinase C inhibitors or by protein kinase C down-regulation, indicating that this enzyme is involved in the action of all these agents. A controlled elevation of the cytosolic Ca2+ concentration ([Ca2+]cyt) over the range of 0.1-2.0 microM activated Peth formation in the absence of other agonists. Staurosporin potentiated Ca(2+)-induced Peth formation by shifting the [Ca2+]cyt dose-response curve to the left. Other protein kinase C inhibitors (calphostin C, bisindolylmaleimide) inhibited Ca(2+)-mediated Peth formation, but this inhibition was reduced in staurosporin-treated cells. Okadaic acid potentiated PLD activation by TPA, but suppressed PLD activation by elevated [Ca2+]cyt. Desensitization of TPA-induced PLD activity did not affect PLD activation by Ca2+. These data indicate that [Ca2+]cyt and protein kinase C control distinct pathways of PLD activation, but the Ca(2+)-mediated pathway is suppressed by a staurosporin-sensitive protein kinase. Both mechanisms contribute to vasopressin-induced Peth formation in intact hepatocytes. Activation of protein kinase A enhanced vasopressin-induced Peth formation, but not TPA-stimulated or Ca(2+)-stimulated stimulated Peth formation. Protein kinase A acted by enhancing hormonal Ca2+ mobilization, rather than by directly activating PLD, and thereby shifted the balance of Ca(2+)-dependent and protein kinase C-dependent activation mechanisms of PLD in intact cells. |
| Databáze: | OpenAIRE |
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