scholarly journals Thrombin-induced platelet responses differ in requirement for receptor occupancy. Evidence for tight coupling of occupancy and compartmentalized phosphatidic acid formation.

1981 ◽  
Vol 256 (18) ◽  
pp. 9393-9396
Author(s):  
H. Holmsen ◽  
C.A. Dangelmaier ◽  
H.K. Holmsen
Keyword(s):  
Phosphatidic Acid ◽  
Receptor Occupancy ◽  
Acid Formation ◽  
Tight Coupling

Thrombin-Induced Responses In Human Platelets Differ In Their Requirement For Receptor Occupancy; Evidence For Tight Coupling Between Occupancy And Formation Of Phos- Phatidic Acid

1981 ◽  
Author(s):  
Holm Holmsen ◽  
Carol A Dangelmaier ◽  
Holm-Kjetil Holmsen
Keyword(s):  
Phosphatidic Acid ◽  
Time Course ◽  
Shape Change ◽  
Receptor Occupancy ◽  
Acid Synthesis ◽  
Human Platelets ◽  
Dense Granule ◽  
Cyclic Process ◽  
Tight Coupling ◽  
Acid Hydrolases

Thrombin causes secretion of dense granule constituents from platelets. The time course and extent of this response is unaltered if thrombin is rapidly neutralized after secretion has started, indicating that a sustained occupancy of the thrombin receptors is not required.Using a 50-fold excess of hirudin to neutralize thrombin, we show here that the shape change and aggregation responses also are independent on sustained receptor occupancy. In contrast, the secretion of acid hydrolases, liberation of [3H-]arachidonate (from phospholipids in platelets prelabeled with [3H]arachidonate) and formation of [32P]phosphatidic acid (in platelets prelabeled with 32P-orthophosphate) induced by thrombin were immedately stopped by hirudin. However, the incorporation of 32P into phosphatidylinositol and breakdown of [3H]phospha- tidyl inositol continued unaffected after thrombin removal. Thrombin-induced platelet responses can thus be subdivided into two classes according to their requirement for receptor occupancy: The first class (shape change, aggregation, dense granule secretion phosphatidylinositol breakdown and phosphatidylinositol synthesis) requires a short, initial occupancy, while the second class (acid hydrolase secretion, arachidonate liberation and phospha- tidic acid synthesis) requires an occupancy that is sustained as long as the response is executed. The increased turnover of phosphoinositides is a cyclic process, and our results show that only one step - the formation of phosphatidic acid from diacylglyceride and ATP - is tightly coupled to receptor occupancy by the agonist.

Study of the Involvement of Phosphatidic Acid Formation in the Expression of Wound-Responsive Genes in Cotton

Lipids ◽  
2018 ◽  
Vol 53 (6) ◽  
pp. 589-599
Author(s):  
Angeliki Bourtsala ◽  
Ioannis Dafnis ◽  
Angeliki Chroni ◽  
Theodora Farmaki ◽  
Dia Galanopoulou
Keyword(s):  
Phosphatidic Acid ◽  
Acid Formation

scholarly journals Tight coupling of thrombin-induced acid hydrolase secretion and phosphatidate synthesis to receptor occupancy in human platelets

1984 ◽  
Vol 222 (1) ◽  
pp. 157-167 ◽  
Author(s):  
H Holmsen ◽  
C A Dangelmaier ◽  
S Rongved
Keyword(s):  
Time Course ◽  
Gel Filtration ◽  
Specific Radioactivity ◽  
Metabolic Stress ◽  
Receptor Occupancy ◽  
Human Platelets ◽  
Acid Hydrolase ◽  
Tight Coupling ◽  
Acid Hydrolases ◽  
Subsequent Increase

Human platelets incubated with [32P]Pi and [3H]arachidonate were transferred to a Pi-free Tyrode's solution by gel filtration. The labile phosphoryl groups of ATP and ADP as well as Pi in the metabolic pool of these platelets had equal specific radioactivity which was identical to that of[32P]phosphatidate formed during treatment of the cells with thrombin for 5 min. Therefore, the 32P radioactivity of phosphatidate was a true, relative measure for its mass. The thrombin-induced formation of[32P]-phosphatidate had the same time course and dose-response relationships as the concurrent secretion of acid hydrolases. 125I-alpha-Thrombin bound maximally to the platelets within 13s and was rapidly dissociated from the cells by hirudin; readdition of excess 125I-alpha-thrombin caused rapid rebinding of radioligand. This binding-dissociation-rebinding sequence was paralleled by a concerted start-stop-restart of phosphatidate formation and acid hydrolase secretion. [3H]Phosphatidylinositol disappearance was initiated upon binding but little affected by thrombin dissociation and rebinding. ATP deprivation caused similar changes in the time courses for [32P]-phosphatidate formation and acid hydrolase secretion which were different from those of [3H]phosphatidylinositol disappearance. The metabolic stress did not alter the magnitude (15%) of the initial decrease in phosphatidylinositol-4,5-bis[32P]phosphate, but did abolish the subsequent increase of phosphatidylinositol-4,5-bis[32P]-phosphate in the thrombin-treated platelets. It is concluded that in thrombin-treated platelets (1) phosphatidate synthesis, but not phosphatidylinositol disappearance, is tightly coupled to receptor occupancy and acid hydrolase secretion in platelets, (2) successive phosphorylations to phosphatidylinositol-4,5-bisphosphate is unlikely to be the main mechanism for phosphatidylinositol disappearance, and (3) only a small fraction (15%) of phosphatidylinositol-4,5-bisphosphate is susceptible to hydrolysis.

The acylation of 1-acyl-sn-glycero-3-phosphate by neuronal nuclei and microsomal fractions of immature rabbit cerebral cortex

1990 ◽  
Vol 68 (3) ◽  
pp. 641-647 ◽  
Author(s):  
R. Roy Baker ◽  
H.-Y. Chang
Keyword(s):  
Cerebral Cortex ◽  
Phosphatidic Acid ◽  
Lysophosphatidic Acid ◽  
Monounsaturated Fatty Acids ◽  
Acid Formation ◽  
Nuclear Fraction ◽  
Neuronal Nucleus ◽  
Neuronal Nuclei ◽  
Low Concentrations ◽  
Rabbit Cerebral Cortex

The acylation of 1-acyl-sn-glycero-3-phosphate to form phosphatidic acid was studied using a neuronal nuclear fraction N1 and microsomal fractions P3, R (rough), S (smooth), and P (neuronal microsomes from nerve cell bodies) isolated from cerebral cortices of 15-day-old rabbits. The assays contained this lysophospholipid, ATP, CoA, MgCl2, NaF, dithiothreitol, and radioactive palmitate, oleate, or arachidonate. Of the subfractions, N1 and R had the highest specific activities (expressed per micromole phospholipid in the fraction). The rates with oleate were two to four times the values seen for phosphatidic acid formation from sn-[3H]glycero-3-phosphate and oleoyl-CoA. Using oleate or palmitate, fraction R had superior specific rates to N1 at low lysophosphatidic acid concentrations. With increasing lysophospholipid concentrations the specific rates of N1 and R came closer together and maintained at least a twofold superiority over fraction P. Fraction S had the lowest specific rates of phosphatidic acid formation. Fractions N1, R, and P showed a preference for palmitate and oleate over arachidonate, particularly at low concentrations of lysophosphatidic acid. For N1 and R, the preference was also more marked at higher concentrations of fatty acid. Thus a selectivity for saturated and monounsaturated fatty acids was shown in the formation of phosphatidic acid, as was a concentration of acylating activity in the neuronal nucleus and the rough endoplasmic reticulum.Key words: 1-acyl-sn-glycero-3-phosphate, acylation, neuronal nuclei, microsomes, cerebral cortex.

Fatty Acid Binding Protein: Stimulation of Microsomal Phosphatidic Acid Formation

1997 ◽  
Vol 341 (1) ◽  
pp. 112-121 ◽  
Author(s):  
Christopher A. Jolly ◽  
Timothy Hubbell ◽  
William D. Behnke ◽  
Friedhelm Schroeder
Keyword(s):  
Fatty Acid ◽  
Phosphatidic Acid ◽  
Fatty Acid Binding Protein ◽  
Binding Protein ◽  
Acid Formation ◽  
Fatty Acid Binding ◽  
Acid Binding Protein ◽  
Stimulation Of

Phospholipase D1 regulates high-affinity IgE receptor-induced mast cell degranulation

Blood ◽  
2004 ◽  
Vol 104 (13) ◽  
pp. 4122-4128 ◽  
Author(s):  
Tomohiro Hitomi ◽  
Juan Zhang ◽  
Liliana M. Nicoletti ◽  
Ana Cristina G. Grodzki ◽  
Maria C. Jamur ◽  
...  
Keyword(s):  
Mast Cell ◽  
Phosphatidic Acid ◽  
Mast Cell Degranulation ◽  
Dominant Negative ◽  
Acid Formation ◽  
Wild Type ◽  
High Affinity ◽  
Phospholipase D1 ◽  
High Affinity Ige Receptor

Abstract To investigate the role of phospholipase D (PLD) in FcϵRI signaling, the wild-type or the catalytically inactive forms of PLD1 or PLD2 were stably overexpressed in RBL-2H3 mast cells. FcϵRI stimulation resulted in the activation of both PLD1 and PLD2. However, PLD1 was the source of most of the receptor-induced PLD activity. There was enhanced FcϵRI-induced degranulation only in cells that overexpressed the catalytically inactive PLD1. This dominant-negative PLD1 enhanced FcϵRI-induced tyrosine phosphorylations of early signaling molecules such as the receptor subunits, Syk and phospholipase C-γ which resulted in faster release of Ca2+ from intracellular sources. Therefore, PLD1 negatively regulates signals upstream of the Ca2+ response. However, FcϵRI-induced PLD activation required Syk and was downstream of the Ca2+response, suggesting that basal PLD1 activity rather than that activated by cell stimulation controlled these early signaling events. Dominant-negative PLD1 reduced the basal phosphatidic acid formation in unstimulated cells, which was accompanied by an increase in FcϵRI within the lipid rafts. These results indicate that constitutive basal PLD1 activity by regulating phosphatidic acid formation controls the early signals initiated by FcϵRI aggregation that lead to mast cell degranulation. (Blood. 2004;104:4122-4128)

Verapamil inhibits phosphatidic acid formation and modifies phosphoinositide metabolism in stimulated platelets

1990 ◽  
Vol 182 (3) ◽  
pp. 457-464 ◽  
Author(s):  
Sheryl T. Homa ◽  
Shah Nawaz Khan ◽  
Dolores M. Conroy ◽  
Andrew E. Speak ◽  
Anthony D. Smith
Keyword(s):  
Phosphatidic Acid ◽  
Acid Formation ◽  
Phosphoinositide Metabolism

THE INCORPORATION OF α-GLYCEROPHOSPHATE-32P INTO THE LIPIDS OF RAT BRAIN PREPARATIONS: II. ON THE BIOSYNTHESIS OF MONOPHOSPHOINOSITIDE

1967 ◽  
Vol 45 (1) ◽  
pp. 63-70 ◽  
Author(s):  
F. Possmayer ◽  
K. P. Strickland
Keyword(s):  
Phosphatidic Acid ◽  
Rat Brain ◽  
Isotope Dilution ◽  
Time Course ◽  
Acid Formation ◽  
Dilution Experiments ◽  
Phosphatide Acid

Previous investigations conducted in this laboratory showed a number of differences in the cytosine nucleotide requirement for the incorporation of α-glycerophosphate (α-G32P) into the monophosphoinositide of rat brain preparations compared to the pathway described by Paulus and Kennedy, where α-glycerophosphate → phosphatide acid → CDP-diglyceride → monophosphoinositide, and CTP is specifically required. Experiments were carried out with rat brain preparations to determine the nature of the mechanism whereby CDP-choline is as effective as or more effective than CTP in stimulating the incorporation of α-G32P into monophosphoinositide. Isotope dilution experiments in which unlabeled phosphatidic acid and CDP-diglyceride were used, yielded results consistent with the view that both of these compounds are intermediates in the incorporation of a-G32P into monophosphoinositide stimulated by either CTP or CDP-choline. Time-course experiments where cytosine nucleotides were added either at the beginning or after 20 minutes produced a pattern of labeling which could be fitted into the above interpretation, provided that newly formed radioactive molecules of phosphatide acid could be used selectively and CTP in some way inhibits phosphatide acid formation or accumulation. The latter could account for the observation that monophosphoinositide becomes far more actively labeled than phosphatidic acid in the presence of added CTP.

scholarly journals The brown adipocyte protein CIDEA promotes lipid droplet fusion via a phosphatidic acid-binding amphipathic helix

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
David Barneda ◽  
Joan Planas-Iglesias ◽  
Maria L Gaspar ◽  
Dariush Mohammadyani ◽  
Sunil Prasannan ◽  
...  
Keyword(s):  
Phosphatidic Acid ◽  
Lipid Droplet ◽  
Metabolic Disorders ◽  
Energy Homeostasis ◽  
Adipocyte Differentiation ◽  
Neutral Lipids ◽  
Brown Adipocyte ◽  
Amphipathic Helix ◽  
Tight Coupling ◽  
Brown Adipocytes

Maintenance of energy homeostasis depends on the highly regulated storage and release of triacylglycerol primarily in adipose tissue, and excessive storage is a feature of common metabolic disorders. CIDEA is a lipid droplet (LD)-protein enriched in brown adipocytes promoting the enlargement of LDs, which are dynamic, ubiquitous organelles specialized for storing neutral lipids. We demonstrate an essential role in this process for an amphipathic helix in CIDEA, which facilitates embedding in the LD phospholipid monolayer and binds phosphatidic acid (PA). LD pairs are docked by CIDEA trans-complexes through contributions of the N-terminal domain and a C-terminal dimerization region. These complexes, enriched at the LD–LD contact site, interact with the cone-shaped phospholipid PA and likely increase phospholipid barrier permeability, promoting LD fusion by transference of lipids. This physiological process is essential in adipocyte differentiation as well as serving to facilitate the tight coupling of lipolysis and lipogenesis in activated brown fat.

Sign in / Sign up

Export Citation Format

Share Document