The Phospholipase C Linked P2y-Purinergic Receptor

1990 ◽  
pp. 266-271
Author(s):  
J. L. Boyer ◽  
C. L. Cooper ◽  
M. W. Martin ◽  
G. L. Waldo ◽  
A. J. Morris ◽  
...  
Keyword(s):  
Phospholipase C ◽  
Purinergic Receptor

Agonist and Guanine Nucleotide Regulation of P2Y Purinergic Receptor-Linked Phospholipase C

1990 ◽  
pp. 181-195
Author(s):  
J. L. Boyer ◽  
M. W. Martin ◽  
C. L. Cooper ◽  
G. L. Waldo ◽  
A. J. Morris ◽  
...  
Keyword(s):  
Phospholipase C ◽  
Purinergic Receptor ◽  
Guanine Nucleotide ◽  
Nucleotide Regulation

scholarly journals Stimulation of phosphatidate synthesis in endothelial cells in response to P2-receptor activation. Evidence for phospholipase C and phospholipase D involvement, phosphatidate and diacylglycerol interconversion and the role of protein kinase C

1992 ◽  
Vol 287 (1) ◽  
pp. 31-36 ◽  
Author(s):  
J R Purkiss ◽  
M R Boarder
Keyword(s):  
Endothelial Cells ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Phosphatidic Acid ◽  
Phospholipase C ◽  
Phospholipase D ◽  
Purinergic Receptor ◽  
Diacylglycerol Kinase ◽  
Kinase C ◽  
Stimulation Of

To investigate the stimulation of phosphatidic acid formation in bovine aortic endothelial cells by P2-purinergic agonists, we labelled AG4762 cells with [32P]P1 and stimulated in the presence of butanol. Under these conditions phospholipase D generated [32P]phosphatidylbutanol, whereas the [32P]phosphatidic acid from phospholipase C and diacylglycerol kinase was unchanged. The action of various purinergic agonists on both [32P]phosphatidic acid and [32P]phosphatidylbutanol was consistent with the presence of a P2Y receptor. The stimulation of phospholipase D was dependent on extracellular Ca2+ and was mostly transient (completed within 3 min), whereas the initial stimulation of phospholipase C was independent of extracellular Ca2+, followed by a Ca(2+)-dependent phase. The agonist stimulation of phospholipase D was dependent on protein kinase C, as judged by its sensitivity to the relatively selective protein kinase C inhibitor Ro 31-8220. These results show that purinergic-receptor-mediated stimulation of phosphatidic acid has three phases: an initial Ca(2+)-independent stimulation of phospholipase C, an early but transient Ca(2+)- and protein kinase C-dependent stimulation of phospholipase D, and a sustained Ca(2+)-dependent stimulation of phospholipase C. Using propranolol to inhibit phosphatidate phosphohydrolase, we provide evidence that phosphatidic acid derived from purinergic-receptor-mediated stimulation of the phospholipase C/diacylglycerol kinase route can itself be converted back into diacylglycerol.

scholarly journals Oscillations of Phospholipase C Activity Triggered by Depolarization and Ca2+Influx in Insulin-secreting Cells

2004 ◽  
Vol 279 (19) ◽  
pp. 19396-19400 ◽  
Author(s):  
Sophia Thore ◽  
Oleg Dyachok ◽  
Anders Tengholm
Keyword(s):  
Plasma Membrane ◽  
Phospholipase C ◽  
Evanescent Wave ◽  
Fluorescent Protein ◽  
Purinergic Receptor ◽  
Dynamic Control ◽  
Pleckstrin Homology Domain ◽  
Resting Cells ◽  
Cellular Processes ◽  
Green Fluorescent

Phospholipase C (PLC) is a ubiquitous enzyme involved in the regulation of a variety of cellular processes. Its dependence on Ca2+is well recognized, but it is not known how PLC activity is affected by physiological variations of the cytoplasmic Ca2+concentration ([Ca2+]i). Here, we applied evanescent wave microscopy to monitor PLC activity in parallel with [Ca2+]iin individual insulin-secreting INS-1 cells using the phosphatidylinositol 4,5-bisphosphate- and inositol 1,4,5-trisphosphate-binding pleckstrin homology domain from PLCδ1fused to green fluorescent protein (PHPLCδ1-GFP) and the Ca2+indicator fura red. In resting cells, PHPLCδ1-GFP was located predominantly at the plasma membrane. Activation of PLC by muscarinic or purinergic receptor stimulation resulted in PHPLCδ1-GFP translocation from the plasma membrane to the cytoplasm, detected as a decrease in evanescent wave-excited PHPLCδ1-GFP fluorescence. Using this translocation as a measure of PLC activity, we found that depolarization by raising extracellular [K+] triggered activation of the enzyme. This effect could be attributed both to a rise of [Ca2+]iand to depolarizationper se, because some translocation persisted during depolarization in a Ca2+-deficient medium containing the Ca2+chelator EGTA. Moreover, oscillations of [Ca2+]iresulting from depolarization with Ca2+influx evoked concentration-dependent periodic activation of PLC. We conclude that PLC activity is under tight dynamic control of [Ca2+]i. In insulin-secreting β-cells, this mechanism provides a link between Ca2+influx and release from intracellular stores that may be important in the regulation of insulin secretion.

scholarly journals P2-purigenic receptors regulate phospholipase C and adenylate cyclase activities in immortalized Schwann cells

1996 ◽  
Vol 314 (2) ◽  
pp. 555-561 ◽  
Author(s):  
Liliana N. BERTI-MATTERA ◽  
Pamela L. WILKINS ◽  
Zuhayr MADHUN ◽  
Deborah SUCHOVSKY
Keyword(s):  
Adenylate Cyclase ◽  
Phospholipase C ◽  
Schwann Cells ◽  
Purinergic Receptor ◽  
Rank Order ◽  
Receptor Subtype ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Proliferation And Differentiation ◽  
Immortalized Schwann Cells

Schwann cells play an important role in both the development and regeneration of peripheral nerves. Proliferation and differentiation of Schwann cells are critically dependent on changes in the levels of cAMP. ATP is a fast excitatory transmitter in the peripheral nervous system, inducing depolarization of the vagus nerve through occupancy of P2-purinergic receptors. In the present study we demonstrate that extracellular ATP stimulates phospholipase C and inhibits adenylate cyclase activities in cultured Schwann cells. Addition of ATP inhibited, in a concentration-dependent manner, forskolin- or isoprenaline-stimulated adenylate cyclase activity. The rank order of potency corresponding to different purinergic receptor agonists was 2 - methylthio-ATP > ATP = ADP ⩾ adenosin eFS685´-[γ-thio]triphosphate (ATP[S]) > UTP, consistent with the involvement of a P2y subtype. Adenosine and adenosine 5´-[α,β-methylene]triphosphate (pp[CH2pA) were ineffective. Preincubation with pertussis toxin completely blocked this inhibitory effect. When Schwann cells were pre-labelled with myo-[3H]inositol and incubated in Hanks' balanced salt solution containing Ca2+ and Mg2+, addition of ATP[S] resulted in a concentration-dependent increase in the release of InsP with a concomitant increase in intracellular free [Ca2+] ([Ca2+]i). Under these conditions, the effects of both ATP and UTP were of lower magnitude. Removal of Ca2+ and Mg2+ from the assay medium resulted in a significant increase in the effects of ATP[S], ATP and UTP. The decreased response observed in the presence of both bivalent cations (1.2 mM Ca2+ and 1 mMMg2+) could not be explained either by increased degradation of ATP by Ca2+/Mg2+-dependent nucleotidases or by cation influx. The rank order of potency for the effects of agonists on phospholipase C activity was ATP[S] = adenosine 5´-[γ-imido]triphosphate > ATP = UTP > ADP, indicating the involvement of a P2u receptor subtype in this response. Adenosine, AMP and pp[CH2]pA were ineffective. These results demonstrate that immortalized Schwann cells express P2u and P2y purinoceptors, which are coupled to stimulation of phospholipase C and inhibition of adenylate cyclase, respectively. Our observations unveil signal-transduction pathways that may be used by ATP to regulate proliferation and differentiation of Schwann cells, and ultimately to influence nerve homoeostasis.

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