Effects of vasopressin on the synthesis of phosphatidylethanolamines and phosphatidylcholines by isolated rat hepatocytes

Tijburg, Lilian B.M.; Schuurmans, E. A. J. M.; Geelen, M.J.H.; Golde, L.M.G. Van

doi:10.1016/0005-2760(87)90216-5

Cited by 22 publications

(18 citation statements)

References 29 publications

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“…The cytosolic activity was determined in the absence or presence of 500 pg total liver phospholipid (24). The total activity of CTP:phosphoethanolamine cytidylyltransferase was assayed in the cytosol by measurement of the rate of conver-sion of [1,2-'4Clphosphoethanolamine into CDP-[1,2-"CJethanolamine (25).…”

Section: Methodsmentioning

confidence: 99%

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Effects of ethanol feeding on hepatic lipid synthesis

Tijburg

Maquedano

Bijleveld

et al. 1988

Archives of Biochemistry and Biophysics

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Rats were fed a high-fat, liquid diet containing either 36% of total calories as ethanol or an isocaloric amount of sucrose, for a period up to 35 days. At different time intervals we measured the effects of ethanol administration on the activities of a number of key enzymes involved in hepatic lipid synthesis. At the start of the experimental period the activities of acetyl-CoA carboxylase and fatty acid synthase, measured in liver homogenates, increased in the control as well as in the ethanol-fed group. After 35 days these enzyme activities were still elevated but there were no significant differences between the two groups. In hepatocytes isolated from controls as well as from ethanol-fed rats, short-term incubations with ethanol induced an increase in the rate of fatty acid synthesis and in the activities of acetyl-CoA carboxylase and fatty acid synthase. However, no alterations in the regulation of these enzymes by short-term modulators of lipogenesis were apparent in hepatocytes isolated from alcohol-treated animals. The results do not indicate a major role for the enzymes of de ncruo fatty acid synthesis in the development of the alcoholic fatty liver. The amount of liver triacylglycerols increased in ethanol-fed rats during the entire treatment period, whereas the hepatic levels of phosphatidylcholine and phosphatidylethanolamine were not affected by ethanol ingestion. Ethanol administration for less than 2 weeks increased the activities of phosphatidate phosphohydrolase, diacylglycerol acyltransferase, and microsomal phosphocholine cytidylyltransferase, whereas the cytosolic activity of phosphocholine cytidylyltransferase was slightly decreased. Upon prolonged ethanol administration the activities of these enzymes were slowly restored to control values after 35 days, suggesting development of some kind of adaptation. It is interesting that, although the activities of phosphatidate phosphohydrolase and diacylglycerol acyltransferase were restored to the levels found in the control rats, this effect was not accompanied by a stabilization or decrease of the concentration of hepatic triacylglycerols. 0 1988 Academic press, inc.

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Section: Methodsmentioning

confidence: 99%

“…Separation and quantification of TG, PC, and PE were carried out as described previously (25). Sera of three rats were combined and serum lipoproteins were separated according to Terpstra (29).…”

Section: Methodsmentioning

confidence: 99%

Effects of ethanol feeding on hepatic lipid synthesis

Tijburg

Maquedano

Bijleveld

et al. 1988

Archives of Biochemistry and Biophysics

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“…The level of diacylglycerol has also been reported to regulate the CDP-ethanolamine pathway (47,48) since this lipid is a substrate for ethanolaminephosphotransferase. We therefore measured the diacylglycerol content of control and Mc/PSS1 cells and found that the amount of this lipid was approximately the same in control cells (4.4 Ϯ 0.5 nmol/mg protein) and (4.0 Ϯ 0.5 nmol/mg protein) Mc/PSS1 cells.…”

Section: Overexpression Of Ptdser Synthase-1 Inhibits Ptdetn Synthesimentioning

confidence: 99%

“…The supply of diacylglycerols has also been implicated in the regulation of the CDP-ethanolamine pathway (47,48) by virtue of this lipid being a substrate for ethanolaminephosphotransferase. Similarly, under some metabolic conditions, diacylglycerols can regulate the CDP-choline pathway for PtdCho synthesis at the level of the cholinephosphotransferase (59 -61).…”

Section: Overexpression Of Ptdser Synthase-1 Inhibits Ptdetn Synthesimentioning

confidence: 99%

“…Unlike the cytidylyltransferase of the CDPcholine biosynthetic pathway, there is no evidence that the activity of ET is regulated by reversible translocation to and from membranes (44). ET is presumed to be a cytosolic protein that neither requires lipids for activity nor is tightly associated with membranes (47,(53)(54)(55). However, some association of ET with ER membranes has been detected in immunogold electron microscopy studies (53).…”

Section: Overexpression Of Ptdser Synthase-1 Inhibits Ptdetn Synthesimentioning

confidence: 99%

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Cloning and Expression of Mouse Liver Phosphatidylserine Synthase-1 cDNA

Stone

Cui

Vance

1998

Journal of Biological Chemistry

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In eukaryotic cells, phosphatidylserine (PtdSer) is synthesized by two distinct synthases on the endoplasmic reticulum by a base-exchange reaction in which the polar head-group of an existing phospholipid is replaced with serine. We report the cloning and expression of a cDNA for mouse liver PtdSer synthase-1. The deduced protein sequence is >90% identical to that of PtdSer synthase-1 from Chinese hamster ovary cells and a sequence from a human myeloblast cell line. PtdSer synthase-1 cDNA was stably expressed in M.9.1.1 cells which are mutant Chinese hamster ovary cells defective in PtdSer synthase-1 activity, are ethanolamine auxotrophs, and have a reduced content of PtdSer and phosphatidylethanolamine (PtdEtn). The growth defect of M.9.1.1 cells was eliminated, and a normal phospholipid composition was restored in the absence of exogenous ethanolamine, implying that the cloned cDNA encoded PtdSer synthase. Mouse liver PtdSer synthase-1 was also expressed in McArdle 7777 rat hepatoma cells. In addition to a 3-fold higher in vitro serine-exchange activity, these cells also exhibited enhanced choline-and ethanolamine-exchange activities and incorporated more [ 3 H]serine into PtdSer than did control cells. However, the levels of PtdSer and PtdEtn in cells overexpressing PtdSer synthase-1 activity were not increased. Excess PtdSer produced by the transfected cells was rapidly decarboxylated to PtdEtn and the degradation of PtdSer, and/or PtdEtn derived from PtdSer, was increased. Moreover, the CDP-ethanolamine pathway for PtdEtn biosynthesis was inhibited. These data suggest that (i) cellular levels of PtdSer and PtdEtn are tightly controlled, and (ii) the metabolism of PtdSer and PtdEtn is coordinately regulated to maintain phospholipid homeostasis.

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Enhancement of phospholipid hydrolysis in vasopressin-stimulated BHK-21 and H9c2 cells

et al. 1995

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The hydrolysis of phospholipids in vasopressin-stimulated baby hamster kidney (BHK)-21 and H9c2 myoblastic cells was investigated. Phosphatidylcholine and phosphatidylethanolamine in these cells were pulse labelled with [3H]glycerol, [3H]myristate, [3H]choline or [3H]ethanolamine, and chased with the non-labelled precursor until linear turnover rates were obtained. When cells labelled with [3H]glycerol or [3H]myristate were stimulated by vasopressin, no significant decrease in the labelling of phosphatidylcholine was detected, but the labelling of phosphatidic acid was elevated. However, the labellings of phosphatidylethanolamine and its hydrolytic product were not affected by vasopressin stimulation. When the cells were pulse labelled with [3H]-choline, vasopressin stimulation caused a decrease in the labelled phosphatidylcholine with a corresponding increase in the labelled choline. The apparent discrepancy between the two types of labelling might be explained by the recycling of labelled phosphatidic acid back into phosphatidylcholine, thus masking the reduction in the labelled phospholipid during vasopressin stimulation. Alternatively, the labelled choline produced by vasopressin stimulation was released into the medium, thus reducing the recycling of label precursor back into the phospholipid and making the decrease in the labelling of phosphatidylcholine readily detectable. Further studies revealed that vasopressin treatment caused an enhancement of phospholipase D activity in these cells. The presence of substrate-specific phospholipase D isoforms in mammalian tissues led us to postulate that the differential stimulation of phospholipid hydrolysis by vasopressin was caused by the enhancement of a phosphatidylcholine-specific phospholipase D in both BHK-21 and the H9c2 cells.

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Effects of vasopressin on the synthesis of phosphatidylethanolamines and phosphatidylcholines by isolated rat hepatocytes

Cited by 22 publications

References 29 publications

Effects of ethanol feeding on hepatic lipid synthesis

Effects of ethanol feeding on hepatic lipid synthesis

Cloning and Expression of Mouse Liver Phosphatidylserine Synthase-1 cDNA

Enhancement of phospholipid hydrolysis in vasopressin-stimulated BHK-21 and H9c2 cells

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