Animals ; Humans ; Signal Transduction ; Sphingomyelin Phosphodiesterase ; metabolism

Neutral sphingomyelinase 2 (nSMase2), which located mainly on the plasma membrane, hydrolyzes sphingomyelin into ceramide and plays an important role in the physiological and pathological regulation of cell apoptosis, cell growth arrest, and inflammation. nSMase2 is also involved in the development of Alzheimer's disease and the bone growth.Under neutral pH and the presence of Ca(2+), Mg(2+), and Mn(+), the activity of nSMase2 is induced by oxidative stress through phosphorylation. Furthermore, the induced interaction of anionic phospholipids and the signaling molecules like receptor for activated C-kinase 1/embryonic ectodermal development with nSMase2 are also crucial mechanisms of protein activation. In the review, recent research advances in the structure and function of nSMase2 and its underlying mechanisms are summarized.
Animals ; Humans ; Molecular Structure ; Signal Transduction ; Sphingomyelin Phosphodiesterase ; chemistry ; physiology

To understand the cytotoxic mechanism of MPP+, we examined the involvement of ceramide in MPP+ -induced cytotoxicity to human neuroblastoma SH-SY5Y cells. When SH-SY5Y cells were exposed to MPP+, MPP+ induced dose-dependent cytotoxicity accompanied by 2-fold elevation of intracellular ceramide levels in SH-SY5Y cells. Three methods were used to test the hypothesis that the elevated intracellular ceramide is related to MPP+ -induced cytotoxicity: C2-ceramide was directly applied to cells, sphingomyelinase (SMase) was exogenously added, and oleoylethanolamine (OE) was used to inhibit degradation of ceramide. Furthermore, inhibition of ceramide-activated protein phosphatase (CAPP), the effector of ceramide, using okadaic acid (OA) attenuated cell death but treatment of fumonisin B1, the ceramide synthase inhibitor, did not alter the cytotoxic effect of MPP+. Based on these, we suggest that the elevation of intracellular ceramide is one of the important mediators in MPP+ -induced cell death.
Cell Death ; Humans* ; Neuroblastoma* ; Okadaic Acid ; Sphingomyelin Phosphodiesterase

Our understanding of the functions of neutral sphingomyelinase (N-SMase) signaling has advanced over the past decade. In this review, we focus on the roles and regulation of N-SMase 1, N-SMase 2, N-SMase 3, an enzyme that generates the bioactive lipid ceramide through the hydrolysis of the membrane lipid sphingomyelin. A large body of work has now implicated N-SMase 2 in a diverse set of cellular functions, physiological processes, and disease pathologies. We focus on different aspects of this enzyme's regulation from transcriptional, post-translational, and biochemical. Furthermore, we expected N-SMase involvement in cellular processes including inflammatory signaling, cell growth, apoptosis, and tumor necrosis factor which in turn play important roles in pathologies such as cancer metastasis, variable disease, and other organ system disorders. Lastly, we examine avenues where targeted N-SMase inhibition may be clinically beneficial in disease scenarios.
Apoptosis ; Breast Neoplasms* ; Hydrolysis ; Membranes ; Neoplasm Metastasis ; Pathology ; Physiological Processes ; Sphingomyelin Phosphodiesterase* ; Tumor Necrosis Factor-alpha

Ceramide is the most abundant lipid in the epidermis and plays a critical role in maintaining epidermal barrier function. Overall ceramide content in keratinocyte increases in parallel with differentiation, which is initiated by supplementation of calcium and/or vitamin C. However, the role of metabolic enzymes responsible for ceramide generation in response to vitamin C is still unclear. Here, we investigated whether vitamin C alters epidermal ceramide content by regulating the expression and/or activity of its metabolic enzymes. When human keratinocytes were grown in 1.2 mM calcium with vitamin C (50 mug/ml) for 11 days, bulk ceramide content significantly increased in conjunction with terminal differentiation of keratinocytes as compared to vehicle controls (1.2 mM calcium alone). Synthesis of the ceramide fractions was enhanced by increased de novo ceramide synthesis pathway via serine palmitoyltransferase and ceramide synthase activations. Moreover, sphingosine-1-phosphate (S1P) hydrolysis pathway by action of S1P phosphatase was also stimulated by vitamin C supplementation, contributing, in part, to enhanced ceramide production. However, activity of sphingomyelinase, a hydrolase enzyme that converts sphingomyelin to ceramide, remained unaltered. Taken together, we demonstrate that vitamin C stimulates ceramide production in keratinocytes by modulating ceramide metabolic-related enzymes, and as a result, could improve overall epidermal barrier function.
Ascorbic Acid* ; Calcium ; Epidermis ; Humans ; Hydrolysis ; Keratinocytes ; Serine C-Palmitoyltransferase ; Sphingomyelin Phosphodiesterase ; Vitamins*

The present study was undertaken to observe the quality and quantity of lipids in the adult worms of Chinese liverfluke, Clonorchis sinensis. Lipid extraction was done by the methods of Folch et a1. (l957) and Kenny (1952), and then the extracted lipid fractions of the worm were separated by thin layer chromatography. Those fractions were also subjected to perform the quantitative analyses of glycerides, cholesterols and phospholipids. The results obtained were summarized as follows: Total amount of glyceride was 37.56 mg per gram of worm tissue and the amount of monoglyceride was 8.34 mg per gm; diglyceride, 15.46 mg per gm; and triglyceride, 12.86 mg per gm. Total amount of cholesterol was 3.30 mg per gm of worm tissue, and the esterified cholesterol (1.72 mg/gm) was a little more than that of free cholesterol (1.26 mg/gm). The following 8 phospholipids were detected in the worm tissue of C. sinensis, i.e., lysophosphatidylcholine, phosphatidylcholine, phophatidylinositol, sphingomyelin, phosphatidylglycerol, phosphatidylserine, phosphatidylethanolamine and an unknown phospholipid.
parasitology-helminth-trematoda ; Clonorchis sinensis ; biochemistry ; glyceride ; cholesterol ; phospholipid ; lipid ; lysophosphatidylcholine ; phosphatidylcholine ; phophatidylinositol ; sphingomyelin ; phosphatidylglycerol ; phosphatidylserine ; phosphatidylethanolamine

The role of sphingomyelinase (SMase) activation and mitogen activated protein kinases (MAPKs) activation in cellular apoptosis was investigated during the hyperthermic treatment of HL-60 human leukemia cells. Treating the cells for 1 h at 43oC caused more than 50% of cellular apoptosis within several hours. The neutral-SMase activity in the cells treated for 1 h at 42degrees C was slightly increased but decreased in the cells treated at 43degrees C or 44degrees C for the same period whereas the acid SMase activity was slightly increased after heating the cells at 42degrees C and 43degrees C and markedly increased at 44degrees C for 1 h. Treatment of cells with inhibitors of SMase activation and ceramide formation significantly reduced the heat-induced apoptosis. Three major families of mitogen-activated protein kinases (MAPKs) i.e. ERK1/2, p38 and JNK, were activated by the hyperthermic treatment of cells. Inhibition of ERK1/2 with PD98059 exerted little effect on the heat-induced apoptosis and p38 inhibition with SB203580 slightly lessened apoptosis whereas, inhibition of JNK with SP600125 markedly suppressed the heat-induced apoptosis. These results indicate that heat-shock induced the activation of SMase, particularly acid-SMase, thereby causing apoptosis and that JNK played a pivotal role in heat-induced apoptosis in HL-60 leukemia cells.
Apoptosis/*physiology ; Enzyme Activation ; HL-60 Cells ; Heat ; Human ; Mitogen-Activated Protein Kinase Kinases/*metabolism ; Sphingomyelin Phosphodiesterase/*metabolism

OBJECTIVETo investigate the expression of the lysosomal enzyme acid sphingomyelinase (ASMase) in alcohol-induced hepatic fibrosis using a rat model.

METHODSThe model of liver fibrosis was induced by administration of alcohol and high fat diet using 20 rats. Six rats given no alcohol and normal diet served as the control group. Real-time PCR, western blotting, and immunohistochemistry were used to evaluate fibrosis-related changes in the mRNA and protein expressions of ASMase.

RESULTSThe fibrotic liver tissues of the model rats showed significantly higher expression levels of ASMase than the non-fibrotic liver tissues of the control rats (P less than 0.05).

CONCLUSIONExpression of ASMase is increased in the fibrotic liver tissue of an alcohol-induced hepatic fibrosis rat model, suggesting that this lysosomal enzyme may contribute to development of this disease condition.

Animals ; Liver ; enzymology ; Liver Cirrhosis, Alcoholic ; enzymology ; Liver Cirrhosis, Experimental ; enzymology ; Male ; Rats ; Rats, Sprague-Dawley ; Sphingomyelin Phosphodiesterase ; metabolism

Type B Niemann-Pick disease is an autosomal recessive sphingolipidosis due to mutations in the sphingomyelin phosphodiesterase 1 gene (SMPD1). Here we present molecular findings for two sibling patients. One mutation V36A due to c.107T>C in exon 1 is a single nucleotide polymorphism and the other N522S due to c.1565 A>G in exon 6 is a novel missense mutation. This non-fatal missense mutation leads to –20% residual lysosomal acid sphingomyelinase activity in vitro and only results in hepatosplenomegaly without neurologic involvement.
Female ; Humans ; Middle Aged ; Mutation, Missense ; Niemann-Pick Disease, Type B ; genetics ; Polymorphism, Single Nucleotide ; Siblings ; Sphingomyelin Phosphodiesterase ; genetics

PURPOSE: Borage oil (BO) and safflower oil (SO) are efficacious in reversing epidermal hyperproliferation, which is caused by the disruption of epidermal barrier. In this study, we compared the antiproliferative effect of dietary BO and SO. Altered metabolism of ceramide (Cer), the major lipid of epidermal barrier, was further determined by measurement of epidermal levels of individual Cer, glucosylceramide (GlcCer), and sphingomyelin (SM) species, and protein expression of Cer metabolizing enzymes. METHODS: Epidermal hyperproliferation was induced in guinea pigs by a hydrogenated coconut diet (HCO) for 8 weeks. Subsequently, animals were fed diets of either BO (group HCO + BO) or SO (group HCO + SO) for 2 weeks. As controls, animals were fed BO (group BO) or HCO (group HCO) diets for 10 weeks. RESULTS: Epidermal hyperproliferation was reversed in groups HCO + BO (67.6% of group HCO) and HCO + SO (84.5% of group HCO). Epidermal levels of Cer1/2, GlcCer-A/B, and beta-glucocerebrosidase (GCase), an enzyme of GlcCer hydrolysis for Cer generation, were higher in group HCO + BO than in group HCO, and increased to levels similar to those of group BO. In addition, epidermal levels of SM1, serine palmitoyltransferase (SPT), and acidic sphingomyelinase (aSMase), enzymes of de novo Cer synthesis and SM hydrolysis for Cer generation, but not of Cer3-7, were higher in group HCO + BO than in group HCO. Despite an increase of SPT and aSMase in group HCO + SO to levels higher than in group HCO, epidermal levels of Cer1-7, GlcCer-A/B, and GCase were similar in these two groups. Notably, acidic ceramidase, an enzyme of Cer degradation, was highly expressed in group HCO + SO. Epidermal levels of GlcCer-C/D and SM-2/3 did not differ among groups. CONCLUSION: Dietary BO was more prominent for reversing epidermal hyperproliferation by enhancing Cer metabolism with increased levels of Cer1/2, GlcCer-A/B, and SM1 species, and of GCase proteins.
Animals ; Borago* ; Carthamus tinctorius* ; Ceramidases ; Cocos ; Diet ; Epidermis* ; Glucosylceramidase ; Guinea Pigs* ; Guinea* ; Hydrogen ; Hydrolysis ; Metabolism* ; Safflower Oil* ; Serine C-Palmitoyltransferase ; Sphingomyelin Phosphodiesterase