The roles of multiple pathways in regulating bombesin-stimulated phospholipase D activity in Swiss 3T3 fibroblasts
| Autor: | C P Briscoe, Michael J. Cross, Michael J.O. Wakelam, A Martin |
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| Rok vydání: | 1995 |
| Předmět: |
Indoles
medicine.drug_class Phosphatidic Acids Glycerophospholipids Biology Biochemistry Tyrosine-kinase inhibitor chemistry.chemical_compound Mice medicine Phospholipase D Phospholipase D activity Animals Tyrosine Molecular Biology Protein kinase C Protein Kinase C Bombesin Tyrosine phosphorylation Cell Biology 3T3 Cells Molecular biology Genistein Isoflavones enzymes and coenzymes (carbohydrates) Kinetics chemistry Guanosine 5'-O-(3-Thiotriphosphate) Phosphorylation Tetradecanoylphorbol Acetate lipids (amino acids peptides and proteins) Guanosine Triphosphate Protein Tyrosine Phosphatases Vanadates Research Article |
| Zdroj: | The Biochemical journal. 306 |
| ISSN: | 0264-6021 |
| Popis: | The regulation of bombesin-stimulated phospholipase D (PLD) activity in Swiss 3T3 fibroblasts was examined. Increasing protein-tyrosine phosphorylation by using pervanadate to inhibit tyrosine phosphatases was found to stimulate protein kinase C (PKC)-independent [3H]phosphatidylbutanol ([3H]PtdBut) accumulation within 5 min, which continued to increase up to 30 min. The stimulation of PLD activity in response to submaximal [bombesin] could be decreased by approx. 50% by the tyrosine kinase inhibitor genistein, whereas pretreatment with genistein and the PKC inhibitor Ro-31-8220 completely abolished the generation of [3H]PtdBut in response to a maximal concentration of bombesin. The addition of guanosine 5′-[gamma-thio]triphosphate (GTP[S]) into permeabilized cells resulted in an increase in [3H]PtdBut, which was abolished by depletion of cellular ATP. The additional presence of 30 microM GTP[S] did not increase the stimulation of PLD activity by any [bombesin] tested, whereas it was synergistic with that stimulated in response to phorbol 12-myristate 13-acetate. These findings suggest that bombesin-stimulated PLD activity is indirectly regulated by G-proteins, possibly through a kinase intermediate. Furthermore, activation of protein tyrosine kinases is proposed to account for the PKC-independent arm of bombesin-stimulated PLD activity. No evidence was obtained for a form of PLD directly regulated by tyrosine phosphorylation. |
| Databáze: | OpenAIRE |
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