| 1. |
- An, Junghwa, et al.
(författare)
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Permanent Genetic Resources added to Molecular Ecology Resources Database 1 October 2009-30 November 2009
- 2010
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Ingår i: Molecular Ecology Resources. - : Wiley. - 1755-098X .- 1755-0998. ; 10:2, s. 404-408
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Tidskriftsartikel (refereegranskat)abstract
- This article documents the addition of 411 microsatellite marker loci and 15 pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Acanthopagrus schlegeli, Anopheles lesteri, Aspergillus clavatus, Aspergillus flavus, Aspergillus fumigatus, Aspergillus oryzae, Aspergillus terreus, Branchiostoma japonicum, Branchiostoma belcheri, Colias behrii, Coryphopterus personatus, Cynogolssus semilaevis, Cynoglossus semilaevis, Dendrobium officinale, Dendrobium officinale, Dysoxylum malabaricum, Metrioptera roeselii, Myrmeciza exsul, Ochotona thibetana, Neosartorya fischeri, Nothofagus pumilio, Onychodactylus fischeri, Phoenicopterus roseus, Salvia officinalis L., Scylla paramamosain, Silene latifo, Sula sula, and Vulpes vulpes. These loci were cross-tested on the following species: Aspergillus giganteus, Colias pelidne, Colias interior, Colias meadii, Colias eurytheme, Coryphopterus lipernes, Coryphopterus glaucofrenum, Coryphopterus eidolon, Gnatholepis thompsoni, Elacatinus evelynae, Dendrobium loddigesii Dendrobium devonianum, Dysoxylum binectariferum, Nothofagus antarctica, Nothofagus dombeyii, Nothofagus nervosa, Nothofagus obliqua, Sula nebouxii, and Sula variegata. This article also documents the addition of 39 sequencing primer pairs and 15 allele specific primers or probes for Paralithodes camtschaticus.
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| 2. |
- Andersson, David, et al.
(författare)
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Ursolic acid inhibits the formation of aberrant crypt foci and affects colonic sphingomyelin hydrolyzing enzymes in azoxymethane-treated rats
- 2008
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Ingår i: Journal of Cancer Research and Clinical Oncology. - : Springer Science and Business Media LLC. - 1432-1335 .- 0171-5216. ; 134:1, s. 101-107
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Tidskriftsartikel (refereegranskat)abstract
- Ursolic acid (UA) is a pentacyclic triterpenoid, with anti-cancer and anti-inflammatory properties. Sphingomyelin (SM) hydrolysis generates lipid messengers regulating cell survival. Earlier studies showed that UA has anti-proliferative and apoptotic effects on HT29 cells, accompanied by a rapid increase in alkaline sphingomyelinase (Alk-SMase) activity. This study examines the effect of orally administered UA on the formation of aberrant crypt foci (ACF) and intestinal SMase activity in azoxymethane (AOM)-treated rats. Sprague-Dawley rats were divided into eight groups, receiving AOM or vehicle, and fed normal diet or pellets containing 0.11% UA in the initiation or promotion/progression phase. The formation of ACF in the colon and the activities of three types of mucosal SMase were examined. UA significantly reduced the incidence of ACF containing three or more crypts in the initiation group, but had no significant effect in the promotion/progression group. AOM reduced mucosal Alk-SMase activity, and the inhibitory effects could not be prevented by UA. However, in both AOM-treated and normal rats, UA increased the activity of colonic neutral SMase markedly and that of acid SMase activity mildly. These results indicate that UA has chemopreventive effects in the initiation phase of colon cancer associated with changes in SM metabolism.
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| 3. |
- Cheng, Yajun, et al.
(författare)
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Curcumin decreases acid sphingomyelinase activity in colon cancer caco-2 cells
- 2007
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Ingår i: Planta Medica. - : Georg Thieme Verlag KG. - 0032-0943 .- 1439-0221. ; 73:8, s. 725-730
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Tidskriftsartikel (refereegranskat)abstract
- Curcumin has been shown to inhibit cell growth and induce apoptosis in colon cancer cells. The metabolism of sphingomyelin has implications in the development of colon cancer. We examined whether curcumin affects the enzymes that hydrolyse sphingomyelin in Caco-2 cells. The cells were cultured in both monolayer and polarized conditions and stimulated with curcumin. The activities of sphingomyelinases were determined. Sphingomyelin and its hydrolytic products were analysed by thin layer chromatography. The changes of acid sphingomyelinase protein were examined by Western blotting. We found that curcumin reduced the hydrolytic capacity of the cells against choline-labelled sphingomyelin, associated with a mild increase of cellular sphingomyelin in the cells. Analysis of the hydrolytic products revealed that the activity was derived from acid sphingomyelinase not from phospholipase D. The curcumin-induced reduction of acid SMase required more than 8 h stimulation. Western blotting showed reduced acid sphingomyelinase protein after curcumin stimulation. The inhibitory effect was more potent in monolayer cells than in polarised cells. No changes of other sphingomyelinases were identified. In the concentrations inhibiting acid sphingomyelinase, curcumin inhibited DNA synthesis and induced cell death. In conclusion, curcumin inhibits acid sphingomyelinase and the effect might be involved in its anti proliferative property against colon cancer cells.
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| 4. |
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| 5. |
- Cheng, Yajun, et al.
(författare)
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Ezetimibe Inhibits Expression of Acid Sphingomyelinase in Liver and Intestine.
- 2009
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Ingår i: Lipids. - : Wiley. - 0024-4201 .- 1558-9307. ; 44:10, s. 897-906
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Tidskriftsartikel (refereegranskat)abstract
- Ezetimibe inhibits cholesterol absorption in the intestine. Sphingomyelin has strong interactions with cholesterol. We investigated the effects of ezetimibe on Sphingomyelinase (SMase) expression in intestine and liver. After feeding rats with ezetimibe (5 mg/kg per day) for 14 days, acid SMase activities in the liver and in the proximal part of small intestine were reduced by 34 and 25%, respectively. Alkaline SMase (alk-SMase) was increased in the proximal part of the small intestine. Administration of lower doses of ezetimibe reduced acid SMase only in the liver by 14% (P < 0.05). In cell culture studies, ezetimibe decreased acid SMase activity in Hep G2 and Caco-2 cells dose-dependently. The reductions were more rapid for Hep G2 cells than for Caco-2 cells. Western blot showed that acid SMase protein was decreased in both Hep G2 and Caco-2 cells by 100 muM ezetimibe. The SM content was increased in Hep G2 cells but not Caco-2 cells, and total cholesterol content was increased in both cell lines 24 h after stimulation with 100 muM ezetimibe. Mevastatin, the inhibitor of cholesterol synthesis, induced a mild increase in acid SMase activity in Hep G2 cells but not Caco-2 cells. Following the reduction of acid SMase, ezetimibe at high dose slightly increased alk-SMase activity. In conclusion, the study demonstrates an inhibitory effect of ezetimibe on acid SMase activity and expression in both liver and intestine.
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| 6. |
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| 7. |
- Cheng, Yajun, et al.
(författare)
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Psyllium and fat in diets differentially affect the activities and expressions of colonic sphingomyelinases and caspase in mice.
- 2004
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Ingår i: British Journal of Nutrition. - 1475-2662. ; 91:5, s. 715-723
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Tidskriftsartikel (refereegranskat)abstract
- Dietary fibre and fat affect colonic tumourigenesis and inflammation. Sphingomyelin metabolism may have implications for the pathogenesis of colonic tumours and ulcerative colitis. The present study examined the effects of psyllium and fat on the enzymes responsible for sphingomyelin metabolism and apoptosis in the colon. Mice were fed control, psyllium-containing (100 g/kg), high-fat (313 g/kg, 53 % energy as fat) or high-fat plus psyllium diets for 4 weeks. The activities of acid, neutral and alkaline sphingomyelinase (SMase), neutral ceramidase, and caspase 3, 8 and 9 in colonic mucosa were determined. The expressions of alkaline SMase and caspase 3 were examined. The psyllium-containing diet was found to increase significantly the activities of alkaline SMase and caspase 3 and decreased those of acid SMase and neutral ceramidase. The high-fat diet had opposite effects on these enzymes and attenuated the effects of psyllium. Western blotting showed that psyllium increased and high-fat decreased the levels of alkaline SMase and caspase 3 in colonic mucosa. The change in caspase 3 activity was positively correlated with that of alkaline SMase and negatively with acid SMase. No similar changes of acid and alkaline phosphatase activities in the colon or acid and neutral SMase activity in the liver were identified. In conclusion, colonic sphingomyelin metabolism and apoptosis were affected by psyllium and fat in an opposite manner. The results may have implications for colorectal tumourigenesis and inflammation.
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| 8. |
- Cheng, Yajun, et al.
(författare)
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Purification, characterization, and expression of rat intestinal alkaline sphingomyelinase.
- 2002
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Ingår i: Journal of Lipid Research. - 1539-7262. ; 43:2, s. 316-324
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Tidskriftsartikel (refereegranskat)abstract
- Intestinal alkaline sphingomyelinase (SMase) has physiological roles in the digestion of sphingomyelin (SM) and clinical implications in colonic carcinogenesis. In the present work, the enzyme from rat has been purified 1,589-fold with 11% recovery by elution of the intestine with bile salt, precipitation of the proteins by acetone, and several types of chromatographies. Its molecular mass was 58 kDa and optimal pH was 9 to 9.5. Under the optimal conditions, the V(max) was 930 micromol/h/mg and K(m) was about 1.25 mM. The enzyme could hydrolyze phosphatidylcholine at pH 7.4 in the presence of Ca2+; the rate was about 8% of that for SM. The activity against SM was dependent on bile salt. Taurine conjugated bile salts were much more effective than glycine conjugated ones, and the most effective bile salts were taurocholate and taurochenodeoxycholate. 3-[(3-Cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS) and Triton X100 (TX100) had no stimulatory effects. Unlike neutral SMase, intestinal alkaline SMase was not Mg2+ dependent, not inhibited by EDTA, and not inhibited by glutathione. The enzyme was stable during incubation with temperatures up to 50 degree C and in pHs from 7 to 10. Trypsin and chymotrypsin had no effects on its activity, and 10 mM dithiothreitol reduced its activity by 25%. A specific antibody against the enzyme was developed, and Western blot showed that the enzyme was expressed in the intestine but not in other organs. In conclusion, we purified a potentially important SMase in the intestine with several properties different from neutral SMase.
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| 9. |
- Duan, Jianxin, et al.
(författare)
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Understanding the Molecular Activity of Alkaline Sphingomyelinase (NPP7) by Computer Modeling
- 2010
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 49:42, s. 9096-9105
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Tidskriftsartikel (refereegranskat)abstract
- The enzymes in the nucleotide pyrophosphatase/phosphodiesterase (NPP) family have various substrates such as nucleotides, phospholipids, and sphingolipids. The substrate specificity in relation to their structures is largely unknown because no mammalian NPP complex has been crystallized. NPP7, also called alkaline sphingomyelinase (alk-SMase), is a NPP family member that may have important implications in carcinogenesis and cholesterol absorption. The sequence of NPP7 is 36% similar to that of the closest NPP member, but NPP7 has no activity against nucleotides. In this work, we predict the three-dimensional structure of NPP7 by homology modeling using a recently crystallized NPP from bacteria. Using the model, we studied the substrate specificity of the enzyme by docking. The model generated explains the functional changes in previous mutagenesis studies and rationalizes the structural basis for the lack of activity toward nucleotides. An effort to shift the substrate specificity from sphingomyelin (SM) to nucleotide was not successful but revealed a site-directed mutation that increased activity toward SM. In conclusion, this is the first study to predict the structure of a mammalian NPP and its substrate specificity by molecular modeling. The information may be helpful in understanding the functional differences of NPP members.
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| 10. |
- Duan, Rui-Dong, et al.
(författare)
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Changes of activity and isoforms of alkaline sphingomyelinase (nucleotide pyrophosphatase phosphodiesterase 7) in bile from patients undergoing endoscopic retrograde cholangiopancreatography.
- 2014
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Ingår i: BMC Gastroenterology. - 1471-230X. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Alkaline sphingomyelinase (NPP7) is an ecto-enzyme expressed in intestinal mucosa, which hydrolyses sphingomyelin (SM) to ceramide and inactivates platelet activating factor. It is also expressed in human liver and released in the bile. The enzyme may have anti-tumour and anti-inflammatory effects in colon and its levels are decreased in patients with colon cancer and ulcerative colitis. Active NPP7 is translated from a transcript of 1.4 kb, whereas an inactive form from a 1.2 kb mRNA was found in colon and liver cancer cell lines. While the roles of NPP7 in colon cancer have been intensively studied, less is known about the function and implications of NPP7 in the bile. The present study examines the changes of NPP7 in bile of patients with various hepatobiliary diseases.
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| 11. |
- Duan, Rui-Dong, et al.
(författare)
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Effects of bile diversion in rats on intestinal sphingomyelinases and ceramidase.
- 2007
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Ingår i: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. - : Elsevier BV. - 1388-1981. ; 1771:2, s. 196-201
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Tidskriftsartikel (refereegranskat)abstract
- Alkaline sphingomyelinase (Alk-SMase) and neutral ceramidase (N-CDase) in the intestinal microvillar membrane are responsible for dietary sphingomyelin digestion. The activities of the enzymes require the presence of bile salt, and the enzymes can be released into the gut lumen in active forms by bile salts and trypsin. It is unclear to what extent that the intestinal presence of bile salts is critical for the intraluminal activity of these enzymes. We compared the activities of Alk-SMase, N-CDase, and other types of SMases in control and permanently bile diverted rats. In the intestinal tract of control rats, the activity of Alk-SMase was profoundly higher than those of acid and neutral Wases. Bile diversion reduced Alk-SMase activity by 85% in the small intestinal content, and by 68% in the faeces, but did not significantly change the activity in the intestinal mucosa. Western blot showed a marked reduction of the enzyme in the intestinal lumen but not mucosa. N-CDase activities both in the intestinal mucosa and content were reduced by bile diversion. Bile diversion also decreased aminopeptidase N activity in the content and increased that in the mucosa, but had no effects on that of alkaline phosphatase. In conclusion, the presence of bile salts is important for maintaining high intraluminal levels of Alk-SMase and N-CDase, two key enzymes for hydrolysis of sphingomyelin in the gut. We speculate that the sphingomyelin hydrolysis in cholestatic conditions is impaired not only by reduced hydrolytic activity but also by deficient dissociation of the enzymes from the membrane.
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| 12. |
- Duan, Rui-Dong, et al.
(författare)
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Evidence for specific ceramidase present in the intestinal contents of rats and humans.
- 2001
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Ingår i: Lipids. - : Wiley. - 0024-4201 .- 1558-9307. ; 36:8, s. 807-812
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Tidskriftsartikel (refereegranskat)abstract
- A neutral ceramidase activity stimulated by bile salt was previously identified in the intestinal content. Recently, bile salt stimulated lipase (BSSL) was found to have ceramidase activity. It is unknown whether the ceramidase activity previously found is attributable to BSSL. To address this question, we compared the behaviors of high quaternary aminoethyl (HQ) anion exchange chromatography, the distributions, the stability, and the responses to lipase inhibitor between ceramidase and pancreatic BSSL. The proteins from whole small intestinal contents of humans and rats were precipitated by acetone and dissolved in 20 mM Tris buffer pH 8.2. These proteins had neutral ceramidase activity but not BSSL activity against p‐nitrophenyl acetate. When the proteins were subject to HQ chromatography, two peaks of ceramidase activity were identified, which had acid and neutral pH optima, respectively. Neither of them had BSSL activity against p‐nitrophenyl acetate. Western blot using BSSL antiserum failed to identify BSSL protein in the fractions, with high neutral ceramidase activity. In rat intestinal tract, pancreatic BSSL activity was high in the duodenum and declined rapidly in the small intestine, whereas neutral ceramidase activity was low in the duodenum and maintained a high level until the distal part of the small intestine. In addition, orlistat, the inhibitor of lipase, abolished human BSSL activity against p‐nitrophenyl acetate and slightly reduced its activity against ceramide but had no inhibitory effect on ceramidase activity isolated by HQ chromatography. In conclusion, we provide the evidence for a specific ceramidase other than pancreatic BSSL present in the intestinal content. The enzyme may play important roles in digestion of dietary sphingolipids.
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| 13. |
- Duan, Rui-Dong, et al.
(författare)
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Human meconium contains significant amounts of alkaline sphingomyelinase, neutral ceramidase, and sphingolipid metabolites.
- 2007
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Ingår i: Pediatric Research. - : Springer Science and Business Media LLC. - 1530-0447 .- 0031-3998. ; 61:1, s. 61-66
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Tidskriftsartikel (refereegranskat)abstract
- Intestinal alkaline sphingomyelinase (Alk-SMase) and neutral ceramidase may catalyze the hydrolysis of endogenous sphin-gomyelin (SM) and milk SM in human-milk fed infants. The enzymes generate sphingolipid metabolites that may influence gut maturation. Alk-SMase also inactivates platelet-activating factor (PAF) that is involved in the pathogenesis of necrotizing enterocolitis (NEC). We examined whether the two enzymes are expressed in both preterm and term infants and analyzed Alk-SMase, neutral ceramidase, SM, and sphingolipid metabolites in meconium. Meconium was collected from 46 preterm (gestational ages 23-36 wk) and 38 term infants (gestational ages 37-42 wk) and analyzed for Alk-SMase using C-14-choline-labeled SM and for neutral ceramidase using C-14-octanoyl-sphingosine as substrates. Molecular species of SM, ceramide, and sphingosine were analyzed by high-performance liquid chromatography mass spectroscopy. Meconium contained significant levels of Alk-SMase and ceramidase at all gestational ages. It also contained 16-24 carbon molecular species of SM, palmitoyl-and stearoyl-sphingosine, and sphingosine. There were positive correlations between levels of SM and ceramide and between ceramide and sphingosine levels. In conclusion, Alk-SMase and ceramidase are expressed in the gut of both preterm and term newborn infants and may generate bioactive sphingolipid messengers.
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Hu, Siyuan, et al.
(författare)
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Numerical and Experimental Study on Laminar Methane/Air Premixed Flames at Varying Pressure
- 2017
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 105, s. 4970-4975
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Tidskriftsartikel (refereegranskat)abstract
- Laminar methane/air premixed Bunsen flames were studied using detailed numerical simulations and laser diagnostics. In the numerical simulations one-dimensional and two-dimensional configurations were considered with detailed transport properties and chemical kinetic mechanism. In the measurements OH PLIF was employed. The flame structures vary with varying equivalence ratio and pressure. For stoichiometric mixture at atmospheric pressure the flame exhibits a single reaction zone structure, while at high-pressures the flame exhibits a two-reaction zone structure: an inner premixed flame and an outer diffusion flame. The predicted two-zone structure is confirmed in the OH PLIF measurements. Using the numerical and the experimental data the methods of flame-cone-angle and flame-area have been used to extract the laminar flame speed for different equivalence ratios and pressures. It is found that although the flame cone angle method is widely used, it yields a lower accuracy than that of the flame surface area method. The inlet velocity of the burner is shown to affect the accuracy of extracted laminar flame speed. It is suggested that the most suitable inlet velocity of methane-air mixture is about 6 times the laminar flame speed.
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| 18. |
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| 19. |
- Liu, Fuli, et al.
(författare)
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Ursodeoxycholic acid differentially affects three types of sphingomyelinase in human colon cancer Caco 2 cells.
- 2006
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Ingår i: Cancer Letters. - : Elsevier BV. - 1872-7980 .- 0304-3835. ; 235:1, s. 141-146
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the effects of UDCA on sphingomyelinase (SMase) in Caco 2 cells cultured in monolayer and polarized conditions. Alkaline SMase activity was high in polarized cells whereas. acid and neutral SMase activities were high in monolayer cells. In polarized cells, UDCA increased alkaline SMase expression and caspase 3 activity but had no effect on acid and neutral SMases. In monolayer cells, UDCA reduced both acid and neutral SMase activities, inhibited cell proliferation, but had little effect on alkaline SMase and caspase 3 activities. In conclusion, UDCA differentially affects SMasc activity, cell proliferation, and apoptosis in colonic cells depending on the cell conditions. (c) 2005 Elsevier Ireland Ltd. All rights reserved.
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| 20. |
- Liu, J J, et al.
(författare)
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Activation of neutral sphingomyelinase participates in ethanol-induced apoptosis in Hep G2 cells
- 2000
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Ingår i: Alcohol and Alcoholism. - 1464-3502. ; 35:6, s. 569-573
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Tidskriftsartikel (refereegranskat)abstract
- The mechanism underlying ethanol-induced apoptosis in liver cells is not clear. Sphingomyelin (SM) metabolism is a novel signal transduction pathway that has an impact on apoptosis in many cell types. We investigated whether the SM pathway is involved in ethanol-induced apoptosis in the liver. Hep G2 cells were treated with ethanol followed by assaying apoptosis, sphingomyelinase (SMase) activity, caspase-3 activity, and the changes of SM content in the cells. We found that ethanol dose-dependently increased apoptosis and the effect was accompanied by increases of caspase-3 activity and neutral SMase activity. At concentrations of 80 and 160 mM, ethanol significantly increased caspase-3 activity by 120% and neutral SMase activity by 24%. The activity of acid SMase was only slightly increased without statistical significance. C(2)-ceramide, the exogenous SM metabolite, mimicked the effects of ethanol on apoptosis and caspase-3 activation. When the SM content was determined 24 h after treatment with ethanol, its level was 15% lower than that of controls. The results indicate that metabolism of SM triggered by neutral SMase participates in ethanol-induced apoptosis in Hep G2 cells and activation of caspase-3 is involved in the apoptotic pathway.
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| 21. |
- Rodrigo, Gloria, et al.
(författare)
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Antiproliferative effects of curcuphenol, a sesquiterpene phenol.
- 2010
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Ingår i: Fitoterapia. - : Elsevier BV. - 1873-6971 .- 0367-326X. ; 81:7, s. 762-766
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Tidskriftsartikel (refereegranskat)abstract
- Curcuphenol is a sesquiterpene isolated from sponges and plants having several significant biological activities. The present study explored its effect on cell proliferation and apoptosis in Caco-2 human colon cancer cells. It was demonstrated that curcuphenol in concentrations in the range of 29-116microg/ml inhibited cell proliferation and DNA replication and induced cell death in a dose-dependent manner. The induction of apoptosis was associated with a stimulation of the activity of caspase-3. The findings presented here suggest that curcuphenol has antiproliferative and pro-apoptotic properties.
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| 22. |
- Wu, Jun, et al.
(författare)
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Acid sphingomyelinase is induced by butyrate but does not initiate the anticancer effect of butyrate in HT29 and HepG2 cells
- 2005
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Ingår i: Journal of Lipid Research. - 1539-7262. ; 46:9, s. 1944-1952
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Tidskriftsartikel (refereegranskat)abstract
- Butyric acid and sphingomyelin (SM) affect colonic tumorigenesis. We examined the potential link between butyrate stimulation and SM metabolism in colonic and hepatic cancer cell lines. After incubating HT29 and HepG2 cells with butyrate and other short-chain fatty acids, we found that butyrate increased acid but not neutral or alkaline sphingomyelinase (SMase) activity by 10- to 20-fold. The effects occurred after 16 h of incubation and were associated with reduced SM and phosphatidylcholine contents and increased ceramide levels. Northern blotting showed increased acid SMase mRNA levels in these cells after butyrate stimulation. Propionate was less potent, and acetate had no effect. No similar changes of acid phosphatase could be identified. At concentrations that increased acid SMase expression, butyrate inhibited cell proliferation, activated caspase 3, and induced apoptosis. However, the antiproliferative and apoptotic effects of butyrate preceded the changes of acid SMase and were not affected by knocking down acid SMase expression by small, interfering RNA. In addition, butyrate-induced acid SMase expression was not affected by blocking the caspase pathway. In conclusion, butyrate regulates SM metabolism by stimulating acid SMase expression in colon and liver cancer cells, but the increased acid SMase is not a critical mechanism for initiating the anticancer effects of butyrate.
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| 23. |
- Wu, Jun, et al.
(författare)
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Cloning of alkaline sphingomyelinase from rat intestinal mucosa and adjusting of the hypothetical protein XP_221184 in GenBank.
- 2005
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Ingår i: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. - : Elsevier BV. - 1388-1981. ; 1687:1-3, s. 94-102
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Tidskriftsartikel (refereegranskat)abstract
- Intestinal alkaline sphingomyelinase (alk-SMase) digests sphingomyelin and the process may influence colonic tumorigenesis and cholesterol absorption. We recently identified the gene of human alk-SMase and cloned the cDNA. Cross-species screening of homology in GenBank found a hypothetical rat protein, XP_221184, with 491 amino acid residues, which shares 73% identity with human alk-SMase. Based on the cDNA sequence of this protein, we cloned a cDNA from rat intestinal mucosa by RT-PCR. The cloned cDNA encodes a protein with 439 amino acid residues and higher (85%) identity with human alk-SMase. The cloned cDNA differed from the XP_221184 cDNA in splice sites linking exons 2 and 3, and exons 3 and 4, respectively. In the sequence of the cloned protein, the predicted activity motif, sphingomyelin binding sites, and potential glycosylation sites in human alk-SMase are all conserved. To confirm the cloned protein is the real form of alk-SMase, native alk-SMase was purified from rat intestine and subjected to proteolytic digestion followed by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry and electrospray ionization (ESI) tandem mass spectrometry. Seven tryptic peptides were found to match the cloned protein sequence. Transient expression of the cloned cDNA linked with a myc tag in COS-7 cells demonstrated high SMase activity, with an optimal pH at 9.0 and a specific dependence on taurocholate and taurochenodeoxycholate. The expressed protein reacted with both anti-myc and anti-human alk-SMase antibodies. Northern blotting of rat tissues revealed high levels of mRNA in jejunum but not in other tissues. In conclusion, we cloned rat alk-SMase cDNA from rat intestine, adjusted the putative rat alk-SMase protein in GenBank, and confirmed the specific expression of the gene in the small intestine.
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| 24. |
- Wu, Jun, et al.
(författare)
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Identification of one exon deletion of intestinal alkaline sphingomyelinase in colon cancer HT-29 cells and a differentiation-related expression of the wild type enzyme in Caco-2 cells.
- 2004
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Ingår i: Carcinogenesis. - : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 25:8, s. 1327-1333
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Tidskriftsartikel (refereegranskat)abstract
- phingomyelin (SM) metabolism in the gut has been implicated in colonic tumorigenesis. Intestinal alkaline sphingomyelinase (alk-SMase) hydrolyses SM in the intestinal content and at the brush border. The enzyme activity is decreased in the tissues of human colorectal tumours. This study examines whether site or chain-mutation of alk-SMase occurs in colon cancer HT-29 cells and Caco-2 cells. Total RNA was isolated and the cDNA of alk-SMase was amplified by RT–PCR. The size of the cDNA from HT-29 cells was smaller than that of the wild-type cDNA. DNA sequencing identified a deletion of exon 4 in alk-SMase cDNA in HT-29 cells. No mutation in genomic alk-SMase DNA from exon 3 to 5 was identified. The exon 4 deletion was caused by a shift of RNA splice site in chromosome 17q25. In Caco-2 cells, no mutation of alk-SMase cDNA was identified. Transient expression in COS-7 cells showed that the enzyme from the cDNA in HT-29 cells had little alk-SMase activity whereas that in Caco-2 cells was as active as the wild-type alk-SMase. The deleted region included residue His353, which is predicted to form a substrate-binding site of alk-SMase. H353A substitution resulted in a protein with no alk-SMase activity. In monolayer cultured Caco-2 cells and HT-29 cells the alk-SMase activities were low. However, to culture the cells under polarizing conditions increased alk-SMase activity and reduced SM level in Caco-2 cells. The alk-SMase activity varied in parallel with alkaline phosphatase activity. In conclusion, we identified an inactive deletion in alk-SMase in HT-29 cells, and a differentiation-related expression of the enzyme in Caco-2 cells. The results provide a molecular mechanism related to previous findings of reduced alk-SMase activity in human colon cancers.
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| 25. |
- Wu, Jun, et al.
(författare)
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Intestinal alkaline sphingomyelinase hydrolyses and inactivates platelet-activating factor by a phospholipase C activity.
- 2006
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Ingår i: The Biochemical journal. - 1470-8728. ; 394, s. 299-308
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Tidskriftsartikel (refereegranskat)abstract
- Alkaline sphingomyelinase (alk-SMase) is a new member of the NPP (nucleotide pyrophosphatase/phosphodiesterase) family that hydrolyses SM (sphingomyelin) to generate ceramide in the intestinal tract. The enzyme may protect the intestinal mucosa from inflammation and tumorigenesis. PAF (platelet-activating factor) is a pro-inflammatory phospholipid involved in pathogenesis of inflammatory bowel diseases. We examined whether alk-SMase can hydrolyse and inactivate PAF. [3H]Octadecyl-labelled PAF was incubated with purified rat intestinal alk-SMase or recombinant human alk-SMase expressed in COS-7 cells. The hydrolytic products were assayed with TLC and MS. We found that alkSMase cleaved the phosphocholine head group from PAF and generated 1-O-alkyl-2-acetyl-sn-glycerol. Differing from the activity against SM, the activity against PAF was optimal at pH 7.5, inhibited by EDTA and stimulated by 0.1-0.25 mM Zn2+. The activity was abolished by site mutation of the predicted metal-binding sites that are conserved in all NPP members. Similar to the activity against SM, the activity against PAF was dependent on bile salt, particularly taurocholate and taurochenodeoxycholate. The V(max) for PAF hydrolysis was 374 mumol x h(-1) x (mg of protein)(-1). The hydrolysis of PAF and SM could be inhibited by the presence of SM and PAF respectively, the inhibition of PAF hydrolysis by SM being stronger. The PAF-induced MAPK (mitogen-activated protein kinase) activation and IL-8 (interleukin 8) release in HT-29 cells, and chemotaxis in leucocytes were abolished by alk-SMase treatment. In conclusion, alk-SMase hydrolyses and inactivates PAF by a phospholipase C activity. The finding reveals a novel function, by which alk-SMase may counteract the development of intestinal inflammation and colon cancer.
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| 26. |
- Yang, Liping, et al.
(författare)
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Effects of fat, beef and fiber in diets on activities of sphingomyelinase, ceramidase and caspase-3 in rat colonic mucosa
- 2002
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Ingår i: Medical Principles and Practice. - : S. Karger AG. - 1011-7571 .- 1423-0151. ; 11:3, s. 150-156
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The present study investigates the activity changes of sphingomyelinase (SMase), ceramidase and caspase-3 in colonic mucosa of rats induced by high fat and red meat diets. Method. For a period of 3 weeks, rats were fed protein without fat (control), high fat only, high fat with beef, and high fat with fiber (cellulose) diets. The fat content (22.4%) was constant in the three high fat diets. Then, the colonic mucosae were scraped and homogenized and the activities of SMase, ceramidase and caspase-3 determined. Results: Compared to the control diet, the fat diet and fat with beef diet reduced intestinal alkaline SMase by 80 and 84%, respectively; ceramidase activity by 60 and 92%, respectively, and caspase-3 activity by 40 and 75%, respectively. The activities of acid and neutral SMases were also decreased by fat and fat with beef diets but to a smaller extent than those of alkaline SMase. Supplement of fiber in the fat diet had no effect on the changes of alkaline SMase activity but prevented fat-induced decreases in acid and neutral SMase activities and partially prevented those of ceramidase and caspase-3 activities. The activity of intestinal alkaline phosphatase was not changed by any of the diets. Conclusion: Fat, beef and fiber significantly affect the enzymes responsible for sphingomyelin metabolism and apoptosis in the colon. The effects may have implications in colonic tumorigenesis related to dietary factors.
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| 27. |
- Yang, Liping, et al.
(författare)
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Effects of red meat and fiber in high fat diet on activities of sphingomyelinase, ceramidase and caspase-3 in rat colonic mucosa.
- 2002
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Ingår i: Journal of Nutritional Biochemistry. - 1873-4847. ; 13:8, s. 499-504
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Tidskriftsartikel (refereegranskat)abstract
- Red meat and fiber rich foods are the dietary factors most consistently related to colon carcinogenesis. Although several components in these dietary sources may contribute, the biochemical mechanism by which red meat and fiber affect colorectal carcinogenesis has not yet been established. Sphingomyelin metabolism is a novel signal transduction pathway that may have an impact on colonic tumorigenesis. The present study investigated the activity changes of sphingomyelinase (SMase), ceramidase and caspase-3 in colonic mucosa of rats fed on a high fat control diet, the control diet with beef and the control diet with fiber (cellulose). After a three week feeding period the colonic mucosa were scraped and homogenized and enzyme activities were determined. The fiber diet significantly increased the activities of neutral and acid SMases but had no effect on those of alkaline SMase and neutral ceramidase. The beef diet, on the other hand, significantly reduced neutral ceramidase activity, but had no effect on the activities of any SMase. In addition, the beef diet significantly reduced and the fiber diet increased caspase-3 activity in the colonic mucosa when compared with the control diet. The changes of caspase-3 activities were abolished by preincubating the samples with caspase-3 inhibitor. No significant changes of intestinal alkaline phosphatase could be found among the three dietary groups. In conclusion, fiber and red meat in the high fat diet affected in an opposite way the enzymes responsible for sphingomyelin metabolism and apoptosis in the colon. The effects may have implications in colorectal tumorigenesis.
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| 28. |
- Yin, Shanshan, et al.
(författare)
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In Situ GISAXS Observation and Large Area Homogeneity Study of Slot-Die Printed PS-b-P4VP and PS-b-P4VP/FeCl3 Thin Films
- 2022
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 14:2, s. 3143-3155
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Tidskriftsartikel (refereegranskat)abstract
- Mesoporous hematite (alpha-Fe2O3) thin films with high surface-to-volume ratios show great potential as photoelectrodes or electrochemical electrodes in energy conversion and storage. In the present work, with the assistance of an up-scalable slot-die coating technique, locally highly ordered alpha-Fe2O3 thin films are successfully printed based on the amphiphilic diblock copolymer poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) as a structure-directing agent. Pure PS-b-P4VP films are printed under the same conditions for comparison. The micellization of the diblock copolymer in solution, the film formation process of the printed thin films, the homogeneity of the dry films in the lateral and vertical direction as well as the morphological and compositional information on the calcined hybrid PS-b-P4VP/FeCl3 thin film are investigated. Because of convection during the solvent evaporation process, a similar dimple-type structure of vertically aligned cylindrical PS domains in a P4VP matrix developed for both printed PS-b-P4VP and hybrid PS-b-P4VP/FeCl3 thin films. The coordination effect between the Fe3+ ions and the vinylpyridine groups significantly affects the attachment ability of the P4VP chains to the silicon substrate. Accordingly, distinct feature sizes and homogeneity in the lateral direction, as well as the thicknesses in the perpendicular direction, are demonstrated in the two printed films. By removing the polymer template from the hybrid PS-b-P4VP/FeCl3 film at high temperature, a locally highly ordered mesoporous alpha-Fe2O3 film is obtained. Thus, a facile and up-scalable printing technique is presented for producing homogeneous mesoporous alpha-Fe2O3 thin films.
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| 29. |
- Yin, Shanshan, et al.
(författare)
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Multidimensional Morphology Control for PS-b-P-4 VP Templated Mesoporous Iron (III) Oxide Thin Films
- 2021
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Ingår i: Advanced Materials Interfaces. - : Wiley. - 2196-7350. ; 8:14
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Tidskriftsartikel (refereegranskat)abstract
- Mesoporous alpha-Fe2O3 thin films with large area homogeneity demonstrate tremendous potential in multiple applications. In the present work, the synthesis of morphology-controlled alpha-Fe2O3 thin films is realized with polystyrene-block-poly(4-vinyl pyridine) (PS-b-P4VP) diblock copolymer assisted sol-gel chemistry. The solvent category (DMF and 1,4-dioxane) and polymer-to-FeCl3 ratio used for the solution preparation are systematically varied to tune the morphology of the thin films. For both solvents, DMF and 1,4-dioxane, nanocluster structures are obtained with low PS-b-P4VP concentration. When the concentration of PS-b-P4VP reaches the critical micelle concentration, spherical and wormlike porous structures are specifically formed in the DMF and 1,4-dioxane solvent system, respectively. Further increasing the polymer-to-FeCl3 ratios leads to the enlargement of the spherical pore sizes in the DMF system, whereas the center-to-center distances of the wormlike structures in the 1,4-dioxane system decrease. Moreover, DMF/1,4-dioxane solvent mixtures with different volume ratios are applied for the sol-gel solution preparation to gain more insight into how the solvent selectivity affects the thin film morphology. By adjusting the preferential affinity of the solvent mixture to the polymer blocks, a spherical to wormlike pore shape transition is observed with a critical Delta chi value of around 0.77.
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| 30. |
- Yin, Shanshan, et al.
(författare)
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Tailored fabrication of quasi-isoporous and double layered alpha-Fe2O3 thin films and their application in photovoltaic devices
- 2023
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 455, s. 140135-
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Tidskriftsartikel (refereegranskat)abstract
- A series of α-Fe2O3 thin films with distinct morphologies are prepared via a facile polystyrene-block-polyethylene oxide templated sol–gel method. By tailoring the poor solvent contents and FeCl3-to-polymer weight ratio in the sol–gel solutions, quasi-isoporous α-Fe2O3 thin films with different substructures and thicknesses are obtained. Via a thermal annealing post-treatment, double layered structures are induced by a synergistic dewetting and Oswald ripening effect. Special focus is set on the α-Fe2O3 thin films prepared with no annealing/annealing-medium FeCl3 concentration, as they possess uniform periodic structures, which is suitable to be used as hole blocking modification layer of perovskite solar cells (PSCs). An improved power conversion efficiency (PCE) is obtained when the double layered α-Fe2O3 thin film is applied as the hole blocking modification layer for PSCs. The improved PCE primarily originates from the increased VOC, which probably benefits from the synergistic effect of the suppressed charge carrier recombination at the interfaces, the enhanced light transmittance as well as the superior electron extraction capacity.
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| 31. |
- Zhang, Ping, et al.
(författare)
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Alkaline sphingomyelinase (NPP7) promotes cholesterol absorption by affecting sphingomyelin levels in the gut. A study with NPP7 knockout mice.
- 2014
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Ingår i: American Journal of Physiology: Gastrointestinal and Liver Physiology. - : American Physiological Society. - 1522-1547 .- 0193-1857. ; 306:10, s. 903-908
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Tidskriftsartikel (refereegranskat)abstract
- We previously showed that dietary sphingomyelin (SM) inhibited cholesterol absorption in animals. The key enzyme hydrolyzing SM in the gut is alkaline sphingomyelinase (alk-SMase, NPP7). Here using fecal dual-isotope ratio method we compared cholesterol absorption in the wild type (WT) and alk-SMase knockout (KO) mice. The animals were fed an emulsion containing (14)C-cholesterol and (3)H-sitosterol. The radioactivities in the lipids of the fecal samples collected 4, 8 and 24 h thereafter were determined and the ratio of (14)C/(3)H calculated. We found that the fecal (14)C-cholesterol recovery in the KO mice was significantly higher than in the WT mice. Maximal 92% increase occurred 8 h after feeding. Recovery of (3)H-sitosterol did not differ between the two groups. Accordingly the (14)C/(3)H ratio of fecal lipids was 133% higher at 8 h and 75% higher at 24 h in the KO than in the WT mice. Decreased (14)C-cholesterol was also found in the serum of the KO mice 4 h after feeding. Supplement of SM in the emulsion reduced the differences in fecal (14)C-cholesterol recovery between the WT and KO mice due to a greater increase of (14)C-cholesterol recovery in the WT mice. Without treatment the KO mice had significantly higher SM levels in the intestinal content and feces, but not in the intestinal mucosa or serum. The expression of NPC1L1 in the small intestine was not changed. In conclusion, alk-SMase is a physiological factor promoting cholesterol absorption by reducing SM levels in the intestinal lumen.
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| 32. |
- Zhang, Ping, et al.
(författare)
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Ursolic Acid Inhibits Acid Sphingomyelinase in Intestinal Cells.
- 2012
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Ingår i: Phytotherapy Research. - : Wiley. - 1099-1573 .- 0951-418X.
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Tidskriftsartikel (refereegranskat)abstract
- Ursolic acid (UA) has antiinflammatory and anticancer effects on mammalian cells. Increase in acid sphingomyelinase (SMase) is associated with several inflammatory diseases including inflammatory bowel diseases. The enzyme has become a target for drug discovery. The present study examined the roles of UA on acid SMase in intestinal cells. We found that UA specifically inhibited acid SMase activity in both human colon cancer Caco-2 cells and rat nontransformed IEC-6 intestinal cells in a dose-dependent manner, with 50% inhibition occurred at 30 μM for Caco-2 cells and less than 20 μM for IEC-6 cells. In comparison with some chemicals known to inhibit acid SMase, UA appeared most effective. The decreased acid SMase activity was not associated with significant accumulation of cellular sphingomyelin but significant increase in phosphatidylcholine, the donor of choline for sphingomyelin synthesis. Western blot analysis showed a decreased enzyme levels in the cells after UA stimulation, but real time quantitative polymerase chain reaction (qPCR) failed to show a parallel reduction of acid SMase mRNA after UA stimulation. Finally, UA had no direct effect on acid SMase activity in cell-free extracts. In conclusion, UA has inhibitory effects on acid SMase synthesis and the effect occurs presumably at posttranslational levels. Copyright © 2012 John Wiley & Sons, Ltd.
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| 33. |
- Zhang, Yao, et al.
(författare)
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Crucial role of alkaline sphingomyelinase in sphingomyelin digestion: A study on the enzyme knockout mice.
- 2010
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Ingår i: Journal of Lipid Research. - 1539-7262. ; 52:4, s. 771-781
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Tidskriftsartikel (refereegranskat)abstract
- Alkaline sphingomyelinase (alk-SMase) hydrolyses sphingomyelin (SM) to ceramide in the gut. To evaluate physiological importance of the enzyme, we generated alk-SMase knockout (KO) mice by Cre-LoxP system and studied SM digestion. Both wild type (WT) and the KO mice were fed 3H-palmitic acid labeled SM together with milk SM by gavage. The lipids in intestinal content, intestinal tissues, serum and liver were analysed by TLC. In KO mice, non-digested 3H-SM in the intestinal content increased by 6 fold and the formation of 3H-ceramide decreased markedly, resulting in 98% reduction of 3H-ceramide/3H-SM ratio 1 h after gavage. The absorbed 3H-palmitic acid portion was decreased by 95%. After three hours, a small increase in 3H-ceramide was identified in distal intestine in KO mice. In feces 3H-SM was increased by 243% and ceramide decreased by 74% in the KO mice. The KO mice also showed significantly decreased radioactivity in liver and serum. Furthermore alkaline phosphatase activity in the mucosa was reduced by 50%, and histological comparison of two female littermates preliminarily suggested mucosal hypertrophy in KO mice. The study provides definite proofs for crucial roles of alk-SMase in SM digestion and points to possible roles in regulating mucosal growth and alkaline phosphatase function.
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