Interleukin-1 stimulates phosphatidic acid-mediated phospholipase D activity in human mesangial cells

1994 ◽  
Vol 266 (4) ◽  
pp. C1093-C1104 ◽  
Author(s):  
S. L. Bursten ◽  
W. E. Harris
Keyword(s):  
Phosphatidic Acid ◽  
Phospholipase D ◽  
Mesangial Cells ◽  
Interleukin 1 ◽  
Type I ◽  
Human Mesangial Cells ◽  
Low Concentrations ◽  
Phosphatidate Phosphohydrolase ◽  
High Concentrations ◽  
Stimulation Of

Previous studies suggest that signal transduction mediated by interleukin-1 (IL-1), acting through an IL-1 receptor type found on T-cells and mesangial cells, may use phosphatidylethanolamine (PE) as a signaling molecule. Evidence presented here indicates that stimulation of human mesangial cells by IL-1 results in activation of a phospholipase D (PLD) that hydrolyzes PE to phosphatidic acid (PA). PLD acts on a subfraction of PE enriched in 1-o-alkyl and 1-o-alkenyl, sn-2-unsaturated species, generating a unique PA subspecies 30-120 s after stimulation. This PA species is subsequently converted to diradylglycerols by phosphatidate phosphohydrolase. The PE-directed PLD activity is abolished by antibodies against the IL-1 type I receptor and against IL-1. This specific PLD activity is also stimulated by low concentrations of 1,2-sn-dilinoleoyl PA, but not by high concentrations of 1-palmitoyl or 1-oleoyl lyso-PA. Blockade of PLD activation by IL-1 antibodies or antibody against the IL-1 receptor is bypassed by stimulation of human mesangial cells with 1,2-sn-dilinoleoyl PA. A novel system of signal cytokine mediation through PA self-amplification is indicated.

scholarly journals Lipid A stimulates phospholipase D activity in rat mesangial cells via a G-protein

1992 ◽  
Vol 281 (3) ◽  
pp. 675-682 ◽  
Author(s):  
W E Harrris ◽  
S L Bursten
Keyword(s):  
Lipid Metabolism ◽  
Phosphatidic Acid ◽  
G Protein ◽  
Phospholipase D ◽  
Lipid A ◽  
Mesangial Cells ◽  
Rapid Decrease ◽  
Gtp Binding ◽  
Unsaturated Acyl ◽  
Stimulation Of

Stimulation of mesangial cells (MC) with the bacterial endotoxin Lipid A activated two enzymes involved in lipid metabolism. First, a phospholipase D hydrolyses phosphatidylethanolamine (PE) to phosphatidic acid (PA), followed by dephosphorylation of PA to 1,2-diacylglycerol (DAG) by PA phosphohydrolase. MC or microsomes from these cells were pre-labelled with [3H]glycerol. A 30-60 s stimulation with 10-100 ng of Lipid A/ml caused a decrease in [3H]glycerol in PE and increased radioactive glycerol in PA. The enzyme responsible for this hydrolysis preferred PE containing unsaturated acyl side chains. DAG was formed from PA within the first 1 min after Lipid A stimulation. Microsomes incubated with 25 mM-NaF to inhibit phospholipase C and to stimulate GTP-binding proteins also caused PE to be converted into PA. The [3H]glycerol and acyl mass of phosphatidylcholine, phosphatidylserine and phosphatidylinositol did not change with either Lipid A or NaF. Addition of guanosine 5′-[gamma-thio]triphosphate to MC microsomes caused the rapid decrease in proportion of PE and increase in PA, followed by an increase in DAG unsaturated acyl mass. These data suggest the concurrent G-protein-dependent activation by Lipid A of a PE-directed phospholipase D and a PA phosphohydrolase.

scholarly journals A shift in the optimum pH of phospholipase D produced by activating long-chain anions

1969 ◽  
Vol 112 (5) ◽  
pp. 795-799 ◽  
Author(s):  
R. H. Quarles ◽  
R. M. C. Dawson
Keyword(s):  
Phosphatidic Acid ◽  
Phospholipase D ◽  
Activity Profile ◽  
Ph Optimum ◽  
Surface Ph ◽  
Electrophoretic Mobilities ◽  
Low Concentrations ◽  
Optimum Ph ◽  
Long Chain

1. The activity of phospholipase D (phosphatidylcholine phosphatidohydrolase, EC 3.1.4.4) towards ultrasonically treated phosphatidylcholine or large phosphatidylcholine particles activated with ether was maximal near pH5, and there was little activity above pH6. 2. When the enzyme was activated by the addition of phosphatidic acid to large phosphatidylcholine particles the pH optimum was shifted to pH6·5 irrespective of the amount of activator added. 3. When the enzyme was activated with low concentrations of dodecyl sulphate the pH optimum was 5·5 with little activity above pH6. With higher concentrations of dodecyl sulphate the pH–activity profile was shifted upwards towards a pH optimum of 6·5–6·6, the magnitude of the shift depending on the extent of the hydrolysis. 4. The shifts in the pH–activity profiles cannot be correlated with changes in the ‘surface pH’ of the substrate particles calculated from the measurement of their ζ-potentials (electrophoretic mobilities).

Pattern differences in experimental fevers induced by endotoxin, endogenous pyrogen, and prostaglandins

1988 ◽  
Vol 254 (4) ◽  
pp. R633-R640 ◽  
Author(s):  
A. Morimoto ◽  
T. Nakamori ◽  
T. Watanabe ◽  
T. Ono ◽  
N. Murakami
Keyword(s):  
Time Course ◽  
Interleukin 1 ◽  
Bacterial Endotoxin ◽  
Endogenous Pyrogen ◽  
Prolonged Time ◽  
Fever Onset ◽  
Long Latency ◽  
Low Concentrations ◽  
High Concentrations ◽  
Experimentally Induced

To distinguish pattern differences in experimentally induced fevers, we investigated febrile responses induced by intravenous (IV), intracerebroventricular (ICV), and intra-preoptic/anterior hypothalamic (POA) administration of bacterial endotoxin (lipopolysaccharide, LPS), endogenous pyrogen (EP), human recombinant interleukin-1 alpha (IL-1), and prostaglandins E2 and F2 alpha (PGE2 and PGF2 alpha). Intravenous LPS, EP, or IL-1 in high concentrations caused biphasic fever. In low concentrations, they induced only the first phase of fever. Latency to onset and time to first peak of fever induced by IV injection of LPS or EP were almost the same as those after ICV or POA injection of PGE2. Fever induced by ICV or POA administration of LPS, EP, IL-1, or PGF2 alpha had a long latency to onset and a prolonged time course. There were significant differences among the latencies to fever onset exhibited by groups that received ICV or POA injections of LPS, EP, or PGF2 alpha and by groups given IV injections of LPS or EP and ICV or POA injections of PGE2. Present observations indicate different patterns of fever produced by several kinds of pyrogens when given by various routes. These results permit us to consider the possibility that there are several mediators or multiprocesses underlying the pathogenesis of fever.

Effects of endogenous calcium transport inhibitor from heart muscle on the active calcium uptake and passive calcium release properties of sarcoplasmic reticulum

1989 ◽  
Vol 67 (9) ◽  
pp. 999-1006 ◽  
Author(s):  
Njanoor Narayanan ◽  
Philip Bedard ◽  
Trilochan S. Waraich
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Heart Muscle ◽  
Calcium Release ◽  
Membrane Vesicles ◽  
Transport Inhibitor ◽  
Low Concentrations ◽  
Active Calcium ◽  
High Concentrations ◽  
Stimulation Of

In the present study, the effects of the cytosolic Ca2+ transport inhibitor on ATP-dependent Ca2+ uptake by, and unidirectional passive Ca2+ release from, sarcoplassmic reticulum enriched membrane vesicles were examined in parallel experiments to determine whether inhibitor-mediated enhancement in Ca2+ efflux contributes to inhibition of net Ca2+ uptake. When assays were performed at pH 6.8 in the presence of oxalate, low concentrations (<100 μg/mL) of the inhibitor caused substantial inhibition of Ca2+ uptake by SR (28–50%). At this pH, low concentrations of the inhibitor did not cause enhancement of passive Ca2+ release from actively Ca2+-loaded sarcoplasmic reticulum. Under these conditions, high concentrations (>100 μg/mL) of the inhibitor caused stimulation of passive Ca2+ release but to a much lesser extent when compared with the extent of inhibition of active Ca2+ uptake (i.e., twofold greater inhibition of Ca2+ uptake than stimulation of Ca2+ release). When Ca2+ uptake and release assays were carried out at pH 7.4, the Ca2+ release promoting action of the inhibitor became more pronounced, such that the magnitude of enhancement in Ca2+ release at varying concentrations of the inhibitor (20–200 μg/mL) was not markedly different from the magnitude of inhibition of Ca2+ uptake. In the absence of oxalate in the assay medium, inhibition of Ca2+ uptake was observed at alkaline but not acidic pH. These findings imply that the inhibition of Ca2+ uptake observed at pH 6.8 is mainly due to decrease in the rate of active Ca2+ transport into the membrane vesicles rather than stimulation of passive Ca2+ efflux; at alkaline pH (pH 7.4), enhanced Ca2+ efflux contributes substantially, if not exclusively, to the decrease in Ca2+ uptake observed in the presence of the inhibitor. It is suggested that if the cytosolic inhibitor has actions similar to those observed in vitro in intact cardiac muscle, acid–base status of the intracellular fluid would be a major factor influencing the nature of its effects (inhibition of Ca2+ uptake or stimulation of Ca2+ release) on transmembrane Ca2+ fluxes across the sarcoplasmic reticulum.Key words: sarcoplasmic reticulum, Ca2+ uptake, Ca2+ release, endogenous inhibitor, heart muscle.

scholarly journals Hypogonadism associated withCyp19a1 (Aromatase) post-transcriptional upregulation inCelf1-KO mice

2015 ◽  
pp. MCB.00074-15 ◽  
Author(s):  
Gaella Boulanger ◽  
Marie Cibois ◽  
Justine Viet ◽  
Alexis Fostier ◽  
Stéphane Deschamps ◽  
...  
Keyword(s):  
Rna Binding ◽  
Hypogonadotropic Hypogonadism ◽  
Type I ◽  
Male Gametes ◽  
Low Concentrations ◽  
Reporter Assays ◽  
High Concentrations ◽  
In Vitro Interaction

CELF1 is a multifunctional RNA-binding protein that controls several aspects of RNA fate. The targeted disruption of theCelf1gene in mice causes male infertility due to impaired spermiogenesis, the post-meiotic differentiation of male gametes. Here, we investigated the molecular reasons that underlie this testicular phenotype. By measuring sex hormone levels, we detected low concentrations of testosterone inCelf1-null mice. We investigated the effect ofCelf1disruption on the expression levels of steroidogenic enzyme genes, and we observed thatCyp19a1was upregulated.Cyp19a1encodes aromatase, which transforms testosterone into estradiol. Administration of testosterone or the aromatase inhibitor Letrozole partly rescued the spermiogenesis defects, indicating that a lack of testosterone associated with excessive aromatase contributes to the testicular phenotype. In vivo and in vitro interaction assays demonstrated that CELF1 binds toCyp19a1mRNA, and reporter assays supported the conclusion that CELF1 directly repressesCyp19a1translation. We conclude that CELF1 downregulatesCyp19a1/Aromatasepost-transcriptionally to achieve high concentrations of testosterone compatible with spermiogenesis completion. We discuss the implications of these findings with respect to reproductive defects in men, including patients suffering from isolated hypogonadotropic hypogonadism and myotonic dystrophy type I.

scholarly journals The temporal relationship between phospholipase activation, diradylglycerol formation and superoxide production in the human neutrophil

1990 ◽  
Vol 271 (1) ◽  
pp. 209-213 ◽  
Author(s):  
N T Thompson ◽  
J E Tateson ◽  
R W Randall ◽  
G D Spacey ◽  
R W Bonser ◽  
...  
Keyword(s):  
Phospholipase D ◽  
Human Neutrophil ◽  
Second Messengers ◽  
Superoxide Production ◽  
Human Neutrophils ◽  
Inositol 1,4,5 Trisphosphate ◽  
Phosphatidate Phosphohydrolase ◽  
Time Courses ◽  
Rapid Activation ◽  
Stimulation Of

Fluctuations in the amounts of choline, inositol 1,4,5-trisphosphate (IP3) and diradylglycerol have been used to monitor phospholipase activation in the human neutrophil. Stimulation of human neutrophils by formylmethionyl-leucylphenylalanine (fMet-Leu-Phe) resulted in a rapid activation of both phosphatidylinositol 4,5-bisphosphate breakdown by phospholipase C and phosphatidylcholine breakdown by phospholipase D. Diradylglycerol accumulation occurred more slowly than that of either choline or IP3 and was inhibited by 30 mM-butanol, suggesting that the bulk was derived from the phospholipase D pathway via phosphatidate phosphohydrolase. Consistent with this is the observation that choline and diradylglycerol are produced in similar amounts. 1,2-Diacylglycerol (DAG) and 1-O-alkyl-2-acyl-sn-glycerol species accumulated with different time courses, indicating that one or more steps in the phospholipase D pathway was selective for the diacyl species. Superoxide production by fMet-Leu-Phe-stimulated neutrophils paralleled DAG accumulation over the first 5 min, but thereafter this production stopped, despite the fact that DAG remained elevated. We conclude that DAG derived from the phospholipase D pathway is only one of the second messengers important in controlling this functional response.

Dopaminergic stimulation of cAMP accumulation in cultured rat mesangial cells

1987 ◽  
Vol 253 (2) ◽  
pp. H358-H364 ◽  
Author(s):  
P. J. Shultz ◽  
J. R. Sedor ◽  
H. E. Abboud
Keyword(s):  
Epithelial Cells ◽  
Mesangial Cells ◽  
Sch 23390 ◽  
Type I ◽  
Camp Accumulation ◽  
Cell Type ◽  
Glomerular Cell ◽  
Da Receptors ◽  
Dopaminergic Stimulation ◽  
Stimulation Of

Dopamine (DA) alters renal hemodynamics, and DA receptors have been demonstrated in isolated glomeruli. To determine the glomerular cell type bearing DA receptors, we studied the effect of dopaminergic agonists and antagonists on adenosine 3',5'-cyclic monophosphate (cAMP) accumulation in rat glomerular mesangial and epithelial cells in culture. DA caused a marked dose- and time-dependent increase in cAMP accumulation in mesangial but not epithelial cells. The stimulatory effect of DA was abolished by the DA antagonists haloperidol, trifluoperazine, and cis-thiothixene but not by beta- or alpha-adrenergic or histamine antagonists. Similar to the effects of DA, two dopamine type I receptor agonists, fenoldopam and SKF 38393, markedly stimulated cAMP accumulation in the mesangial cells. Moreover, the effects of DA were blocked by Sch 23390, a specific DA1 receptor antagonist, but not domperidone, a specific DA2 antagonist. These results show that DA regulates cAMP accumulation in mesangial cells via DA1-type receptors.

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