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PubMed2002

[The ratio of components of sphingomyelin cycle and lipid composition in patients with viral hepatitis].

The aim of the study is the investigation of the content of the lipids and the sphingomyelin cycle components in the liver of the patients suffered from viral hepatitis. The methods used were thin layer chromatography for the detection of the lipid pattern and gas liquid chromatography for evaluation of the sphingomyelin fatty acid's and spectrum and ceramides. In the patients suffered from viral hepatitis HCV with moderate activity of the process cholesterin and triglycerides level were less and lysophospholipids content was two-fold and sphingomyelin level was insignificantly higher comparingly than in patients with low activity of the process. In the group of patients suffered from mixt infection (HCV + HBV) there is decreased cholesterin and both phosphatidylcholin and the sphingomyelin content along with lysophospholipids level elevation. In the fatty acid spectrum the palmitate acid (16:0) and the long chain acids (C22-C24) content were higher comparingly with ceramides. Significant difference is observed in oleic acid (18:1) content being as small as 9.3-9.9% in the liver damaged by viral hepatitis.

Adult↗
PubMed2005

[The influence of tumor necrosis factor alpha on the processes of sphingomyelin cycle and lipid peroxidation in brain].

The influence of tumor necrosis factor alpha (TNF-alpha) on the processes of sphingomyelin cycle activation and intensity of peroxidation in animal brain in vivo has been studied. Alterations in activity of sphingomyelinase, a key sphingomyelin cycle enzyme and in sphingomyelin, ceramide content as well as accumulation of the products of lipid peroxidation (diene conjugates and diene ketons) were measured in the cortex, the cerebellum and the hippocampus of rats 5, 15, 30 min, 1, 2 and 5 hours after TNF-alpha intraperitoneal injection in dosage 100 mkg per animal. It is shown that 2 hours after the injection, TNF-alpha initiated an accumulation of the products of lipid peroxidation, which intensively developed in the cerebellum and the hippocampus. Sphingomyelinase activation was found in the same brain structures. At the initial stage of TNF-alpha action, an increase of lipid peroxidation products correlated with sphingomyelinase activation in the cerebellum and the hippocampus suggesting an interaction of two cell signal systems of sphingomyelin cycle and oxidative system.

Animals↗
PubMed1989

Trifluoperazine stimulates the coordinate degradation of sphingomyelin and phosphatidylcholine in GH3 pituitary cells.

Prior studies demonstrated that 1,2-diacylglycerols stimulated degradation of the choline-containing phospholipids, phosphatidylcholine and sphingomyelin, in GH3 pituitary cells by a phospholipase A2 and a sphingomyelinase, respectively (Kolesnick, R. N. (1987) J. Biol. Chem. 262, 16759-16762). The present studies demonstrate that the phenothiazine trifluoperazine also stimulates degradation of these phospholipids. Trifluoperazine (25 microM) reduced phosphatidylcholine and sphingomyelin levels to 81 and 58% of control, respectively, after 30 min in cells labeled for 48 h with [3H] choline. Choline-containing metabolites were released specifically into the cytosolic fraction. The level of cytosolic phosphocholine, but not choline or CDP-choline, increased to 150% of control. These events were not mediated by inhibition of phosphatidylcholine synthesis. The level of 1,2-diacylglycerols, but not lysophosphatidylcholine or glycerol-3-phosphocholine, also increased. These data are most consistent with phosphatidylcholine degradation via a phospholipase C. Trifluoperazine-stimulated sphingomyelin degradation was accompanied by quantitative generation of ceramides consistent with activation of a sphingomyelinase. In contrast to trifluoperazine, choline-containing metabolites were released into the medium during stimulation by the 1,2-diacylglycerol 1,2-dioctanoyl-glycerol. Although both trifluoperazine and 1,2-dioctanoylglycerol increased ceramide levels, only 1,2-dioctanoylglycerol increased the sphingoid base level from 24 to 43 pmol/10(6) cells. Hence, trifluoperazine appears to deplete an intracellular pool of phosphatidylcholine and sphingomyelin by a different mechanism than 1,2-diacylglycerols. This is the first report of phenothiazine-induced degradation of choline-containing phospholipids.

Animals↗
PubMed1989

Plasma membranes contain half the phospholipid and 90% of the cholesterol and sphingomyelin in cultured human fibroblasts.

The literature suggests that cholesterol and sphingomyelin might be essentially confined to plasma membranes in mammalian cells; however, this premise has thus far escaped a direct test. We explored the issue in three ways. First, we fractionated whole homogenates of cultured human fibroblasts by equilibrium sucrose density gradient centrifugation. We found that the profiles of cholesterol and sphingomyelin were indistinguishable from those of two plasma membrane markers, 5' nucleotidase and [3H]galactose, which was conjugated to the surface of intact cells from an exogenous donor by galactosyltransferase. Second, we determined the relative surface areas of intact cells from their uptake of 1-(4-trimethyl-amino)phenyl-6-phenylhexa-1,3,5-triene, a cationic fluorescent dye which partitions into but does not cross plasma membranes. Relative to human red cell ghosts, the apparent surface area of the fibroblasts was 17,500 microns2/cell while for canine hepatocytes, the value was 11,500 microns2/cell. The relative ratios of cell cholesterol to dye binding (hence, surface area) were quite similar in ghosts, fibroblasts, and liver cells; namely 1.0, 1.12, and 0.67, respectively. Finally, we found that the specific ratios of both cholesterol and sphingomyelin to 5' nucleotidase were only 10% less in gradient-purified plasma membranes than in whole homogenates. Similar results were obtained using an entirely different method of purification: two-phase aqueous partition. The cholesterol and sphingomyelin in fractions rich in other membranes was closely proportional to their 5' nucleotidase content, suggesting that the presence of these lipids reflected contamination by plasma membrane fragments. The 5' nucleotidase/phospholipid ratio in the purified plasma membrane fraction was roughly twice that in whole cells. We conclude that the compartment marked by 5' nucleotidase in cultured human fibroblasts contains approximately 90% of the two named lipids and half the cell phospholipid phosphorus.

Cell Compartmentation↗
PubMed1987

Purification and properties of a phospholipase C that has high activity toward sphingomyelin from Aspergillus saitoi.

An enzyme hydrolyzing sphingomyelin was purified from extracts of solid cultures of Aspergillus saitoi 7041 by fractionation with isopropanol followed by successive column chromatographies on DEAE-Sepharose CL-6B, butyl-Toyopearl 650 M, and phenyl-Sepharose CL-4B. The preparation of purified enzyme was homogeneous and had an activity increased 81-fold over that of the isopropanol fraction. The yield was about 65%. The molecular weight was estimated to be 54,000 by sodium dodecyl sulfate-gel electrophoresis. The enzyme solution had a violet color and contained iron atoms. The enzyme catalyzed the hydrolysis of sphingomyelin to N-acylsphingosine and phosphorylcholine. The optimum pH for hydrolytic activity was around 3.5. The Km values for sphingomyelin and 2-hexadecanoylamino-4-nitrophenylphosphorylcholine were 0.11 and 0.33 mM, respectively. The enzyme also catalyzed the hydrolysis of other phospholipids; the order of its hydrolytic activity at a substrate concentration of 2.5 mM was phosphatidylcholine greater than or equal to sphingomyelin = phosphatidylethanolamine = lysophosphatidylethanolamine greater than phosphatidyl DL-glycerol = phosphatidyl L-serine greater than phosphatidylinositol. From these results, this enzyme appears to be a new type of phospholipase C(phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3).

Aspergillus↗
PubMed1986

Sphingomyelin and ceramide-phosphoethanolamine synthesis by microsomes and plasma membranes from rat liver and brain.

Pulse-chase experiments showed that phosphatidylethanolamine (PE) was the direct precursor for ceramide-phosphoethanolamine, a sphingomyelin analogue, in the same way as phosphatidylcholine was for sphingomyelin. Ceramide-phosphoethanolamine could be identified by incorporation of radioactivity from labeled PE, as well as by its stability in alkaline methanolysis and its ability to be methylated by S-adenosyl-methionine. Ceramide-phosphoethanolamine synthesis from labeled exogenous PE seemed to be independent of exogenous ceramide; it was proportional to the amount of incubated membrane, when taking into account the isotopic dilution of labeled precursor by endogenous PE. Sphingomyelin synthesis, which was demonstrated using natural PC as a substrate, was not possible using dipalmitoyl-PC. The formation of sphingomyelin and ceramide-phosphoethanolamine was demonstrated in microsomes and plasma membranes from rat brain and liver.

Animals↗
PubMed1979

Naturally occurring antibodies to liposomes. I. Rabbit antibodies to sphingomyelin-containing liposomes before and after immunization with unrelated antigens.

Liposomes were prepared from a mixture of sphingomyelin, cholesterol, and dicetylphosphate or L-alpha-dimyristoyl phosphatidylcholine, cholesterol, and dicetylphosphate, in the presence of glucose. The amount of trapped glucose released from these liposomes was monitored after incubation with a variety of normal and immune sera in the presence of guinea pig complement. All normal rabbit sera tested were found to release, in the presence of complement, detectable amounts of trapped glucose from sphingomyelin-containing liposomes. After immunization with a variety of unrelated antigens, the anti-sphingomyelin liposome activity increased signficantly and in direct proportion to the number of injections, despite the fact that the liposomes used in the assay did not contain the relevant antigen used for immunization. Liposomes prepared from dimyristoyl phosphatidylcholine showed only marginal release of their trapped marker when assayed with the same rabbit sera and complement. These liposomes, however, were fully reactive when the appropriate antigen was inserted in their bilayer structure. The antiliposome activity was associated mainly with the IgM antibody class. These results raise the interesting possibility that antigenic stimulation may trigger the activation of lymphocyte clones directed against autologous cell-membrane components that cross-react with artificial model membranes containing sphingomyelin.

Animals↗
PubMed1982

[Immunological detection of sphingomyelin exchange protein in tumors and in embryonic rat liver].

The interaction of postmicrosomal supernatants from the Jensen sarcoma, sarcoma 45, nephroma RA, normal, regeherating and fetal rat livers with antisera to the sphingomyelin exchange protein isolated from hepatoma 27 was studied by double immunodiffusion. It was shown that this protein is present in comparable amounts in all the tumours tested and in fetal rat liver, whereas in normal and regenerating liver its content is negligible. Based on the correlation between the content of sphingomyelin exchange protein in cell cytosols and the amount of sphingomyelin in the corresponding mitochondria it is suggested that this protein is responsible for the presence of sphingomyelin in mitochondria.

Animals↗
PubMed1980

Sphingomyelin suppresses the binding and utilization of low density lipoproteins by skin fibroblasts.

Cultured human skin fibroblasts incubated at 37 degrees C with sonically dispersed, positively charged liposomes containing sphingomyelin internalized and metabolized the phospholipid. Sphingomyelin incorporation into the cells produced a reduction in low density lipoprotein binding and degradation. Lecithin-containing liposomes were much less effective. In addition, incubation with sphingomyelin resulted in a marked increase in acetate incorporation into sterol. These results suggest that sphingomyelin, which is required by cells for membrane synthesis, can influence the regulation of the cell surface low density lipoprotein receptor and intracellular cholesterol balance.

Cells, Cultured↗
PubMed1981

New method for determining lecithin and sphingomyelin in amniotic fluid.

We describe a new method of complete analysis for lecithin, lysolecithin, and sphingomyelin in amniotic fluid. The analysis is based on alkaline hydrolysis of the lecithins and the enzymic hydrolysis of sphingomyelin. The choline formed in each instance is enzymically phosphorylated with [gamma-32P]ATP to yield [gamma-32P]phosphorylcholine, which is isolated by anion-exchange chromatography and shown to be stoichiometrically related to lecithin, lysolecithin, and sphingomyelin. Other phospholipids do not interfere. Using this methodology, we developed three potential approaches to the assessment of fetal lung maturity: the ratio of lecithin plus lysolecithin (total lecithin) to sphingomyelin, the total lecithin concentration, and total lecithin as a percentage of total amniotic fluid phospholipids. All three indices were compared with the lecithin/sphingomyelin ratio obtained by a chromatographic procedure. Our data suggest that measuring the percentage of total lecithin may provide the best means of evaluating fetal lung maturity, but a final judgment must await clinical investigation.

Amniotic Fluid↗
PubMed1994

Localization of O-glycan initiation, sphingomyelin synthesis, and glucosylceramide synthesis in Vero cells with respect to the endoplasmic reticulum-Golgi intermediate compartment.

The identification of an endoplasmic reticulum-Golgi intermediate compartment (ERGIC), defined by the 53-kDa transmembrane marker protein ERGIC-53, has added to the complexity of the exocytic pathway of higher eukaryotic cells. Recently, a subcellular fractionation procedure was established for the isolation of the ERGIC from Vero cells (Schweizer, A., Matter, K., Ketcham, C. M., and Hauri, H.-P. (1991) J. Cell Biol. 113, 45-54) which provides a means to study more precisely the compartmentalization of the various enzymic functions along the early secretory pathway. Here, we have investigated if O-glycan initiation and sphingomyelin synthesis are associated with the ERGIC by analyzing both the responsible enzyme activities and their corresponding products. Moreover, the synthesis of glucosylceramide, the precursor of most glycosphingolipids, was also analyzed. In the purified ERGIC fraction UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (GalNAc transferase) was only minimally enriched, sphingomyelin synthase was not enriched, and UDP-glucose:ceramide-glucosyl transferase specific activity was lower than in the homogenate. On Percoll gradients all three enzymes cofractionated with Golgi markers rather than ERGIC-53. Accordingly, sphingomyelin concentrations were extremely low in the ERGIC fraction. Double immunofluorescence localization of core N-acetylgalactosamine, the product of GalNAc transferase, by monoclonal antibodies against GalNAc-Ser/Thr (Tn antigen) revealed only little apparent overlap with ERGIC-53. This was particularly evident in brefeldin A-treated cells which showed entirely different patterns of Tn antigens and ERGIC-53. The results suggest that in the secretory pathway of Vero cells O-glycan initiation and sphingomyelin as well as glucosylceramide synthesis mainly occur beyond the ERGIC in the Golgi apparatus.

Amino Acid Sequence↗
PubMed1985

Absence of transbilayer diffusion of spin-labeled sphingomyelin on human erythrocytes. Comparison with the diffusion of several spin-labeled glycerophospholipids.

We have measured the transbilayer diffusion at 4 degrees C of spin labeled analogs of sphingomyelin, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidic acid in the human erythrocyte membrane. Measurements were also carried out in ghosts, released without ATP, and on large unilamellar vesicles made with total lipid extract. As reported previously (Seigneuret, M. and Devaux, P.F. (1984) Proc. Natl. Acad. Sci. USA 81, 3751-3755), the amino phospholipids are rapidly transported from the outer to the inner leaflet on fresh erythrocytes, whereas phosphatidylcholine diffuses slowly. We now show that phosphatidic acid behaves like phosphatidylcholine: approximately 10% is internalized in 5 h at 4 degrees C. Under the same experimental conditions, no inward transport of sphingomyelin can be detected. In ghosts resealed without ATP, all glycerophospholipids tested diffuse slowly from the outer to the inner leaflet (approx. 10% in 5 h) while no transport of sphingomyelin is seen. Finally in lipid vesicles, the inward diffusion of all glycerophospholipids is less than 2% in 5 h and a very small transport of sphingomyelin can be measured. These results confirm the existence of a selective inward aminophospholipid transport of fresh erythrocytes and suggest a slow and passive diffusion of all phospholipids on ghosts, resealed without ATP, as well as on lipid vesicles.

Adenosine Triphosphate↗
PubMed1999

Sphingomyelin synthase in rat liver nuclear membrane and chromatin.

The presence of phospholipids in chromatin has been demonstrated, as well as the difference in composition and turnover compared to those present in the nuclear membrane. Recently, some enzymes were also evidenced in chromatin: the base exchange protein complex and neutral sphingomyelinase. The latter has a particular relevance, since sphingomyelin is one of the phospholipids more represented in chromatin. We therefore decided to study the synthesis of sphingomyelin in chromatin and in nuclear membrane isolated from liver nuclei. The evaluation of the enzyme was made (i) using [(3)H]phosphatidylcholine as donor of radioactive phosphorylcholine and (ii) by identifying the product isolated by thin layer chromatography. In both fractions the enzyme phosphatidylcholine:ceramide phosphocholine transferase or sphingomyelin synthase was present, although with higher activity in nuclear membrane. The enzyme present in the chromatin differs in pH optimum and K(m), showing a higher affinity for the substrates than that of nuclear membrane. The results presented show that sphingomyelin synthase is present not only in the cytoplasm at the level of the Golgi apparatus, but also in the nuclei, at the level of either the nuclear membrane or the chromatin.

Animals↗
PubMed1990

Hydrolysis of sphingomyelin and phosphatidylcholine by midgut homogenates of the stable fly.

Qualitative and quantitative analyses were made to characterize the enzymatic degradation of sphingomyelin and phosphatidylcholine by midgut homogenates of the adult stable fly, Stomoxys calcitrans (L.). The results indicated that sphingomyelin was hydrolyzed by an enzyme with sphingomyelinase-like properties, and that phosphatidylcholine was hydrolyzed by an enzyme with properties similar to phospholipase C. The optimum pH for the sphingomyelinase was 7.6, and the rate of hydrolysis of sphingomyelin at that pH was linear from 1 to 4 nmol of substrate and 5 to 25 micrograms of enzyme preparation. Dialysis of the homogenates against Tris-HCl and imidazole buffers resulted in a decrease of sphingomyelinase activity by 59% and 98%, respectively, and the original activity was not restored with the addition of Ca++, Mg++, or Mn++.

Animals↗
PubMed1986

A new variant of sphingomyelinase deficiency (Niemann-Pick): visceromegaly, minimal neurological lesions and low in vivo degradation rate of sphingomyelin.

Three males (aged 10 years, 3 years 9 months and 2 years 8 months) with profound sphingomyelinase deficiency are presented. The sphingomyelin storage in the liver biopsies attained 30-fold, 65-fold and 16-fold increases against controls, respectively. Levels of bis(monoacylglyceryl) phosphate were also increased. In two cases the bone marrow contained foam cells with liquid crystals of sphingomyelin. Besides the visceral involvement dominated by hepatosplenomegaly, all three cases showed discrete, so far stationary (8 years, 42 months and 28 months) neuropathic features and retinal lesions resembling the classical cherry-red spot. Electrophysiological examinations showed a variable reduction of peripheral nerve conduction velocity and prolongation of the latencies of somatosensory, visual and auditory evoked potentials. Ultrastructural examination of skin nerves showed a slight storage, mainly in Schwann cells. In some myelinated fibres there were pseudomyelinic ovoids. The cases therefore displayed features of both A and B types of sphingomyelinase deficiency and should be conventionally classified as intermediate. However, the very low levels of in vivo sphingomyelin hydrolysis (not exceeding 6%, against 30 +/- 10% in type B and 77 +/- 5% in controls) were clearly within the range of type A values (5 +/- 2%). Accordingly, we suggest that the cases may be biochemically classified as variants of type A disease.

Child↗
PubMed1986

The role of sphingomyelin synthetase and sphingomyelinase in 1,2-dimethylhydrazine-induced lipid alterations of rat colonic plasma membranes.

Recently, our laboratory, utilizing the 1,2-dimethylhydrazine model of colonic adenocarcinoma, demonstrated alterations in the 'dynamic component' of fluidity in brush-border membranes prepared from distal colonocytes of rats administered this agent for 5, 10 and 15 weeks, i.e., before the development of colon cancer. Furthermore, changes in the sphingomyelin content and sphingomyelin/phosphatidylcholine molar ratio of these membranes appeared, at least partially, to be responsible for these fluidity alterations. In an attempt to elucidate the mechanism(s) involved in these dimethylhydrazine-induced lipid changes, in the present studies the activities of sphingomyelin synthetase and magnesium-dependent neutral sphingomyelinase, enzymes involved in the synthesis and degradation of this phospholipid, respectively, were examined and compared in distal colonic brush-border membranes prepared from rats after 5, 10 or 15 weeks administration of dimethylhydrazine or diluent. The results of these studies demonstrate that alterations in both these enzymatic activities can be detected after administration of dimethylhydrazine and appear to, at least in part, be responsible for the changes in membrane sphingomyelin composition noted previously. These results as well as a discussion of their possible serve as the basis for the present report.

1,2-Dimethylhydrazine↗
PubMed1978

Effect on sphingomyelin-containing liposomes of phospholipase D from Corynebacterium ovis and the cytolysin from Stoichactis helianthus.

The toxic, sphingomyelin-specific phospholipase D (phosphatidylcholine phosphatidohydrolase EC 3.1.4.4) from Corynebacterium ovis was purified to near homogeneity. It has a molecular weight of 31 000 and a pI of approx. 9.8. Although not cytolytic itself, it protected red cells from hemolysis by staphylococcal sphingomyelinase (beta-hemolysin) and helianthus toxin. The apparently non-enzymatic cytolysin (helianthus toxin) from the sea anemone Stoichactis helianthus also interacts with membrane sphingomyelin. C. ovis and helianthus toxins were compared with regard to their effects on liposome model membranes, and they were found both to produce changes analogous to those in erythrocytes. Only helianthus toxin caused release of trapped glucose marker, but liposomes could be protected from release by pretreatment with C. ovis toxin. Both toxins demonstrated binding to sphingomyelin-containing liposomes, but only the bacterial sphingomyelinase catalyzed the release of choline from these vesicles.

Corynebacterium↗
PubMedDate not supplied

Sphingomyelin inhibition of Ciona intestinalis (Tunicata) cytotoxic hemocytes assayed against sheep erythrocytes.

Hemocytes from the ascidian, Ciona intestinalis, are capable of lysing erythrocytes in vitro following cell membrane contact. With the aim of examining the mechanism of cytotoxicity, we performed inhibition experiments with lipid components of erythrocyte membranes. Cholesterol is not an inhibitor, whereas, among the phospholipids tested, (sphingomyelin, phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine) sphingomyelin inhibits the hemolytic activity of hemocytes. However, thin layer chromatography showed that sphingomyelinase activity was not contained in the chloroform-methanol extracts from hemocyte debris. The inhibition capacity of the components ceramide and phosphorylcholine suggests that the entire sphingomyelin molecule is involved in binding cytolysins. The lysin-lipid interactions probably cause changes in erythrocyte membrane permeability, leading to lysis.

Animals↗