scholarly journals Corticotropin-(1–24)-tetracosapeptide affects protein phosphorylation and polyphosphoinositide metabolism in rat brain

1981 ◽  
Vol 194 (1) ◽  
pp. 283-291 ◽  
Author(s):  
J Jolles ◽  
H Zwiers ◽  
A Dekker ◽  
K W A Wirtz ◽  
W H Gispen
Keyword(s):  
Phosphatidic Acid ◽  
Protein Phosphorylation ◽  
Subcellular Fraction ◽  
Membrane Phospholipids ◽  
Cytosol Fraction ◽  
Phosphatidylinositol Bisphosphate ◽  
Phosphorylation Of Proteins ◽  
Synaptosomal Fraction ◽  
Phosphatidylinositol Phosphate ◽  
Polyphosphoinositide Metabolism

1. Effects of corticotropin-(1–24)-tetracosapeptide on the endogenous phosphorylation of proteins and lipids were studied in a membrane/cytosol fraction prepared from a lysed crude mitochondrial/synaptosomal fraction. 2. The labelling of proteins and lipids was monitored by incubation of the subcellular fraction for 10s with [gamma-32P]ATP. 3. The phosphorylation of proteins was dose-dependently inhibited by the peptide (40% of control incubations at 100 microM-corticotropin). 4. Of the membrane phospholipids only phosphatidylinositol phosphate, phosphatidylinositol bisphosphate and phosphatidic acid became labelled. Corticotropin dose-dependently increased the formation of phosphatidylinositol bisphosphate and inhibited the production of phosphatidic acid (470% and 50% respectively of control incubations, at 100 microM of the peptide) and had no effect on phosphatidylinositol phosphate. 5. Phosphatase activity was observed to act on phosphatidylinositol bisphosphate, phosphatidylinositol phosphate and phosphoprotein but not on phosphatidic acid. 6. Corticotropin interacted with the kinases rather than with the phosphatases. 7. The formation of phosphatidylinositol bisphosphate and phosphatidic acid was maximal at 1–10mM-Mg2+ in the absence of Ca2+, and the production of phosphatidylinositol phosphate was maximal at 30mM-Mg2+. 8. The basal value of lipid phosphorylation decreased with increasing Ca2+ concentration. 9. Ca2+ abolished the effect of corticotropin on phosphatidylinositol bisphosphate formation (470%, 190% and 100% of control incubations at respectively 0, 0.1 and 1 mM-Ca2+). 10. The data provide evidence that the effects of corticotropin on protein phosphorylation and on polyphosphoinositide metabolism in brain membranes are related.

scholarly journals Synthesis of polyphosphoinositides in nuclei of Friend cells. Evidence for polyphosphoinositide metabolism inside the nucleus which changes with cell differentiation

1987 ◽  
Vol 248 (3) ◽  
pp. 765-770 ◽  
Author(s):  
L Cocco ◽  
R S Gilmour ◽  
A Ognibene ◽  
A J Letcher ◽  
F A Manzoli ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Phosphatidic Acid ◽  
Nuclear Membrane ◽  
Isolated Nuclei ◽  
Phosphatidylinositol Bisphosphate ◽  
Phosphatidylinositol Kinase ◽  
Phosphatidylinositol Phosphate ◽  
Friend Cells ◽  
Liver Nuclei ◽  
Polyphosphoinositide Metabolism

Previous work demonstrated the existence of phosphatidylinositol kinase and phosphatidylinositol phosphate kinase in rat liver nuclei, with the suggestion that these activities are in the nuclear membrane [Smith & Wells (1983) J. Biol. Chem. 258, 9368-9373]. Here we show that highly purified nuclei from Friend cells, washed free of nuclear membrane by Triton, can incorporate radiolabel from [gamma-32P]ATP into phosphatidic acid, phosphatidylinositol phosphate and phosphatidylinositol 4,5-bisphosphate. The degree of radiolabelling of phosphatidylinositol bisphosphate is highly dependent on the state of differentiation of the cells, being barely detectable in growing cells and much greater after dimethyl sulphoxide-induced differentiation; this difference is mostly due to different amounts of phosphatidylinositol phosphate in the isolated nuclei. We suggest that polyphosphoinositides are made inside the nucleus and that they have a role in chromatin function; either the phospholipids themselves play a role, or there is a possibility of intranuclear signalling by inositide-derived molecules.

Soluble and membrane-bound polyphosphoinositide phosphohydrolases in mammalian erythrocytes

1988 ◽  
Vol 66 (3) ◽  
pp. 199-207 ◽  
Author(s):  
Suzanne E. Mack ◽  
Frederick B. St. C. Palmer
Keyword(s):  
Phosphatase Activity ◽  
Cetyltrimethylammonium Bromide ◽  
Cytosol Fraction ◽  
Sheep Erythrocytes ◽  
Phosphatidylinositol Bisphosphate ◽  
Membrane Activity ◽  
Phosphatidylinositol Phosphate ◽  
Membrane Bound ◽  
Triton X ◽  
Assay Conditions

Phosphatases and phosphodiesterases that hydrolyse polyphosphoinositides are described in both membrane and cytosol fractions of human, pig, rat, rabbit, and sheep erythrocytes using exogenous substrates. With suitably optimized assay conditions, Ca2+-dependent phosphatidylinositol bisphosphate (PIP2) phosphodiesterase activity was found in the hemoglobin-free cytosol fraction, as well as the membrane. Membrane activity is completely dependent upon Triton X-100 and salt and inhibited by cetyltrimethylammonium bromide (CTAB), while the soluble activity requires CTAB and is inhibited by Triton. A low Ca2+-dependent PIP2 phosphatase activity, not present in other tissues, was also detected. The cation-independent phosphatidylinositol phosphate (PIP) phosphatase is localized in the membrane in most species, while the diesterase and the PIP2 phosphatases (both Mg2+ and Ca2+ dependent) are localized in the cytosol. Rat and rabbit erythrocytes are atypical in having a substantial proportion of their Mg2+ -dependent PIP2 phosphatase activities in the membrane. All activities are lowest in sheep erythrocytes, except the PIP phosphatase, most of which is soluble in this species. Ca2+-dependent PIP2 phosphatase activity is not correlated with the activity or subcellular distribution of any of the other hydrolases and seems to be a separate enzyme. All the phosphoinositide hydrolase activities, particularly the diesterase, are orders of magnitude lower in erythrocytes than in other tissues. Both soluble and membrane diesterase activities are lost as erythrocytes age. Soluble polyphosphoinositide diesterase does not seem to be active with membrane-bound substrate, since pig and sheep erythrocytes that have negligible membrane activity do not respond to Ca2+ loading, yet have substantial diesterase activity in the cytosol. This supports the view that the diesterase is not physiologically functional in normal erythrocytes.

Stimulation of phospholipase D activity and phosphatidic acid production by norepinephrine in rat aorta

1993 ◽  
Vol 264 (3) ◽  
pp. C609-C616 ◽  
Author(s):  
A. W. Jones ◽  
S. D. Shukla ◽  
B. B. Geisbuhler
Keyword(s):  
Phosphatidic Acid ◽  
Phospholipase D ◽  
Time Course ◽  
Rat Aorta ◽  
Functional Responses ◽  
Phosphatidylinositol Bisphosphate ◽  
Phosphatidylinositol Phosphate ◽  
Transphosphatidylation Reaction ◽  
Hydrolysis Of ◽  
Stimulation Of

We sought to relate norepinephrine (NE) stimulation of phosphatidic acid (PA) production to functional responses of rat aorta and pathways for PA production. The time course for changes in PA was closely related to Ca-dependent tonic responses in 42K efflux and contraction. NE (30 microM for 1 min) increased PA and reduced phosphatidylcholine (PC) and phosphatidylinositol (PI) based on Pi analyses and 32P labeling of phospholipids. The 32P-to-Pi ratio in PA (0.8 +/- 0.2, n = 13) was similar to PC (0.8 +/- 0.1, n = 14) but was significantly lower (P < 0.001) than PI (4.6 +/- 0.5, n = 14). The 32P-to-Pi ratio in PA was also lower (P < 0.02) than phosphatidylinositol phosphate and phosphatidylinositol bisphosphate. NE also increased [3H]PA twofold (P < 0.05) when PC was selectively labeled with [3H]myristic acid. These observations are more consistent with PA being formed from the hydrolysis of PC by phospholipase D (PLD) than by the phosphorylation of diacylglycerol produced by the action of phospholipase C. PLD was assayed by the formation of phosphatidylethanol (PEt) via a transphosphatidylation reaction with ethanol (half-maximal stimulation at 0.4-0.5% vol/vol). The time course for PLD stimulation by NE was similar to PA, with significant increases (P < 0.002) during 10 s to 30 min exposure. Once formed, PEt was degraded slowly, with a half time > 3 h. It is concluded that NE stimulates PLD in rat aorta, which forms a significant amount of PA from the hydrolysis of PC.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Toxoplasma LIPIN is essential in channeling host lipid fluxes through membrane biogenesis and lipid storage

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sheena Dass ◽  
Serena Shunmugam ◽  
Laurence Berry ◽  
Christophe-Sebastien Arnold ◽  
Nicholas J. Katris ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Phosphatidic Acid ◽  
De Novo ◽  
Lipid Synthesis ◽  
Parasite Development ◽  
Membrane Biogenesis ◽  
Membrane Phospholipids ◽  
Phosphatidic Acid Phosphatase ◽  
Intracellular Parasites ◽  
Parasite Survival

AbstractApicomplexa are obligate intracellular parasites responsible for major human diseases. Their intracellular survival relies on intense lipid synthesis, which fuels membrane biogenesis. Parasite lipids are generated as an essential combination of fatty acids scavenged from the host and de novo synthesized within the parasite apicoplast. The molecular and metabolic mechanisms allowing regulation and channeling of these fatty acid fluxes for intracellular parasite survival are currently unknown. Here, we identify an essential phosphatidic acid phosphatase in Toxoplasma gondii, TgLIPIN, as the central metabolic nexus responsible for controlled lipid synthesis sustaining parasite development. Lipidomics reveal that TgLIPIN controls the synthesis of diacylglycerol and levels of phosphatidic acid that regulates the fine balance of lipids between storage and membrane biogenesis. Using fluxomic approaches, we uncover the first parasite host-scavenged lipidome and show that TgLIPIN prevents parasite death by ‘lipotoxicity’ through effective channeling of host-scavenged fatty acids to storage triacylglycerols and membrane phospholipids.

scholarly journals Modulation of brain polyphosphoinositide metabolism by ACTH-sensitive protein phosphorylation

Nature ◽  
1980 ◽  
Vol 286 (5773) ◽  
pp. 623-625 ◽  
Author(s):  
J. Jolles ◽  
H. Zwiers ◽  
C. J. van Dongen ◽  
P. Schotman ◽  
K. W. A. Wirtz ◽  
...  
Keyword(s):  
Protein Phosphorylation ◽  
Polyphosphoinositide Metabolism

Potential mediation of somatostatin secretion from canine fundic D-cells by protein kinase c

1987 ◽  
Vol 253 (1) ◽  
pp. G62-G67
Author(s):  
T. Chiba ◽  
K. Sugano ◽  
J. Park ◽  
T. Yamada
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phosphatidic Acid ◽  
Phosphatidyl Inositol ◽  
Membrane Phospholipids ◽  
Kinase C ◽  
Dose Dependent Fashion ◽  
D Cells ◽  
Two Parameters ◽  
Dose Dependent

We examined the possible importance of protein kinase c-dependent mechanisms in mediating the stimulatory effects of gastrin and cholecystokinin (CCK) on the release of somatostatin-like immunoreactivity (SLI) from isolated canine fundic D-cells. Diacylglycerides, presumably the products of phosphoinositide breakdown that activate protein kinasec, and phospholipase C, which catalyzes the production of endogenous diacylglycerides from membrane phospholipids, both stimulated SLI secretion in a dose-dependent fashion. Both classes of agents potentiated the actions of adenosine 3',5'-cyclic monophosphate-dependent agonists but not those of gastrin and CCK. The stimulatory effects of gastrin and CCK correlated with their abilities to enhance the incorporation of 32P into membrane phosphatidyl inositol and phosphatidic acid and promote the release of [3H]inositol trisphosphate from prelabeled D-cells, two parameters of phosphoinositide turnover. These data suggest that protein kinase c may serve to transduce the signals activated by gastrin and CCK in D-cells.

scholarly journals Hormone-induced protein phosphorylation. I. Relationship between secretagogue action and endogenous protein phosphorylation in intact cells from the exocrine pancreas and parotid.

1982 ◽  
Vol 95 (3) ◽  
pp. 903-908 ◽  
Author(s):  
S D Freedman ◽  
J D Jamieson
Keyword(s):  
Protein Phosphorylation ◽  
Exocrine Pancreas ◽  
Second Messengers ◽  
Intact Cells ◽  
Cholecystokinin Octapeptide ◽  
Phosphorylation Of Proteins ◽  
Endogenous Protein ◽  
Dose Dependent Fashion ◽  
Dose Dependent

We undertook studies to determine whether secretagogue action on the exocrine pancreas and parotid is accompanied by phosphorylation of proteins in intact cells. For this purpose, rat pancreatic, and parotid lobules were preincubated with 32Pi for 45 min at 37 degrees C, washed, and then incubated at 37 degrees C in the presence or absence of secretagogues that effect discharge through different second messengers. Among a variety of polypeptides exhibiting enhanced phosphorylation in pancreatic lobules upon a 30-s incubation in the presence of the secretagogues carbamylcholine, cholecystokinin octapeptide, or secretin, one species with an Mr of 29,000 was especially notable for three reasons: (a) its enhanced level of phosphorylation was dependent on the dose of secretagogue used and was still apparent after incubation for 30 min at 37 degrees C; (b) an analogous phosphorylated polypeptide was observed in isoproterenol-stimulated parotid lobules; and (c) in both tissues its selective dephosphorylation was observed upon termination of stimulation by administration of atropine to carbamylcholine-stimulated pancreatic lobules and propranolol to isoproterenol-stimulated parotid lobules. These results suggest that the phosphorylation of one protein with an Mr of 29,000 is closely correlated both temporally and in a dose-dependent fashion with secretagogue action in both the exocrine pancreas and parotid.

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