• YAKHAK HOEJI
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• v.43 no.1
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• pp.85-90
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• 1999

FTY720, a novel immunosuppressant, elevated the level of endogenous sphingoid bases in a dose-dependent manner within 3 hr in $LLC-PK_1$ cells. The relative molar ratio of sphingoid bases expressed as sphingosine/sphinganine (SPN/SPA), a biomarker of altered sphingolipid biosynthesis, in $10{\;}{\mu}M$ of FTY720 showed tow-fold increase as compared with the one in control culture. FTY720 under the serum-free medium condition increased only cytosolic free sphingosine concentration, not sphinganine concentration in a time-dependent manner over the 8 hr incubation under the same condition as in serum free cultures, the SPN/SPA ratio began to fluctuate and the number of floating cells as an indicator of cytotoxicity was increased 8 hr after the addition of FTY720 to cultured cells. These results suggest that the process of FTY720-induced cell death in $LLC-PK_1$ cells.

• Molecules and Cells
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• v.23 no.1
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• pp.11-16
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• 2007

N,N-dimethyl-D-erythro-sphingosine (DMS) is an N-methyl derivative of sphingosine and an inhibitor of protein kinase C (PKC) and sphingosine kinase (SK). In the present study, we examined the effects of DMS on intracellular $Ca^{2+}$ concentration, pH, and glutamate uptake in human 1321N1 astrocytes. DMS increased intracellular $Ca^{2+}$ concentration and cytosolic pH in a concentration-dependent manner. Pretreatment of the cells with the $G_{i/o}$ protein inhibitor PTX and the PLC inhibitor U73122 had no obvious effect. However, removal of extracellular $Ca^{2+}$ with the $Ca^{2+}$ chelator EGTA or depletion of intracellular $Ca^{2+}$ stores with thapsigargin impeded the DMS-induced increase of intracellular $Ca^{2+}$ concentration. Pretreatment of cells with $NH_4Cl$ or monensin reduced the DMS-induced $Ca^{2+}$ increase. However, inhibition of the DMS-induced $Ca^{2+}$ increase with BAPTA did not influence the DMS-induced pH increase. DMS also inhibited glutamate uptake by the 1321N1 astrocytes in a concentration-dependent manner. It also increased intracellular $Ca^{2+}$ and pH in PC12 neuronal cells. Our observations on the effects of DMS on 1321N1 astrocytes and PC12 neuronal cells point to a physiological role of DMS in the brain.

• Archives of Plastic Surgery
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• v.37 no.6
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• pp.726-731
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• 2010

Purpose: Autologous fat grafting is a popular procedure for the correction of the soft tissue depression and deformity. But there are several issues required to be carefully considered in relation to this procedure, mainly about the unpredictability and the low survival rate of the grafted fat due to absorption and partial necrosis. Sphingosine-1-phosphate (S1P) is a lysophospholipid mediator that has been proposed to promote angiogenesis and to regulate the differentiation of adipose derived stromal cells (ASCs). In this study, we analyzed the viability of the grafted fat tissue mixed with S1P into each 12 nude mice (cann.cg-fox1nu/crlori) compared to the group of mice grafted fat tissue only. Methods: Human aspirated fat was grafted subcutaneously into the backs of 8-week-old nude mice with or without S1P. Eight weeks later, the grafted fat was harvested and the weight and volume were checked. The fat was stained with hematoxylin-eosin and 4',6-diamidino-2-phenylindole. Results: S1P group weighed significantly more than the control group (p=0.009), and the volume from the S1P group was considerably larger than that of the control group (p=0.004) either. In histological features, the surviving layer of the S1P group was thicker than the control group and microvasculature appeared to be prominent in the S1P group, especially in the outer layers. Conclusion: These findings suggest that S1P plays a vital role in the soft tissue augmentation, potentially providing a novel point of the control in adipose tissue for microfat graft.

• Biomolecules & Therapeutics
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• v.16 no.2
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• pp.95-99
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• 2008

Apoptosis is essential for a variety of pathophysiological progress. Apoptosis induction by various agents changes cellular morphology, DNA content and lipid membrane composition. Recently, sphingosine 1-phosphate (S1P) is avidly released from not only platelets and erythrocytes but vascular endothelium. Here we established S1P releasing cells by deleting S1P lyase (F9-12 cells). We observed apoptosis induction by the treatment of fumonisin B1 (FB1) in F9-12 cells but not in F9 wild-type cells. We measured high amounts of accumulated S1P and dihydroS1P (DHS1P) in FB1-induced apoptotic F9-12 cells. We also showed DHS1P release in an early stage of the apoptosis induction by FB1 but not by phorbol 12-myristate 13-acetate (PMA)-induced apoptosis, suggesting differential apoptotic processes.

• Molecules and Cells
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• v.38 no.6
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• pp.482-495
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• 2015

Sphingolipids such as ceramide, sphingosine-1-phosphate and sphingomyelin have been emerging as bioactive lipids since ceramide was reported to play a role in human leukemia HL-60 cell differentiation and death. Recently, it is well-known that ceramide acts as an inducer of cell death, that sphingomyelin works as a regulator for microdomain function of the cell membrane, and that sphingosine-1-phosphate plays a role in cell survival/proliferation. The lipids are metabolized by the specific enzymes, and each metabolite could be again returned to the original form by the reverse action of the different enzyme or after a long journey of many metabolizing/synthesizing pathways. In addition, the metabolites may serve as reciprocal biomodulators like the rheostat between ceramide and sphingosine-1-phosphate. Therefore, the change of lipid amount in the cells, the subcellular localization and the downstream signal in a specific subcellular organelle should be clarified to understand the pathobiological significance of sphingolipids when extracellular stimulation induces a diverse of cell functions such as cell death, proliferation and migration. In this review, we focus on how sphingolipids and their metabolizing enzymes cooperatively exert their function in proliferation, migration, autophagy and death of hematopoetic cells, and discuss the way developing a novel therapeutic device through the regulation of sphingolipids for effectively inhibiting cell proliferation and inducing cell death in hematological malignancies such as leukemia, malignant lymphoma and multiple myeloma.

• Molecules and Cells
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• v.43 no.5
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• pp.419-430
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• 2020

The liver is an important organ in the regulation of glucose and lipid metabolism. It is responsible for systemic energy homeostasis. When energy need exceeds the storage capacity in the liver, fatty acids are shunted into nonoxidative sphingolipid biosynthesis, which increases the level of cellular ceramides. Accumulation of ceramides alters substrate utilization from glucose to lipids, activates triglyceride storage, and results in the development of both insulin resistance and hepatosteatosis, increasing the likelihood of major metabolic diseases. Another sphingolipid metabolite, sphingosine 1-phosphate (S1P) is a bioactive signaling molecule that acts via S1P-specific G protein coupled receptors. It regulates many cellular and physiological events. Since an increase in plasma S1P is associated with obesity, it seems reasonable that recent studies have provided evidence that S1P is linked to lipid pathophysiology, including hepatosteatosis and fibrosis. Herein, we review recent findings on ceramides and S1P in obesity-mediated liver diseases and the therapeutic potential of these sphingolipid metabolites.

• Biomolecules & Therapeutics
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• v.25 no.1
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• pp.80-90
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• 2017

Initial discovery on sphingosine 1-phosphate (S1P) as an intracellular second messenger was faced unexpectedly with roles of S1P as a first messenger, which subsequently resulted in cloning of its G protein-coupled receptors, $S1P_{1-5}$. The molecular identification of S1P receptors opened up a new avenue for pathophysiological research on this lipid mediator. Cellular and molecular in vitro studies and in vivo studies on gene deficient mice have elucidated cellular signaling pathways and the pathophysiological meanings of S1P receptors. Another unexpected finding that fingolimod (FTY720) modulates S1P receptors accelerated drug discovery in this field. Fingolimod was approved as a first-in-class, orally active drug for relapsing multiple sclerosis in 2010, and its applications in other disease conditions are currently under clinical trials. In addition, more selective S1P receptor modulators with better pharmacokinetic profiles and fewer side effects are under development. Some of them are being clinically tested in the contexts of multiple sclerosis and other autoimmune and inflammatory disorders, such as, psoriasis, Crohn's disease, ulcerative colitis, polymyositis, dermatomyositis, liver failure, renal failure, acute stroke, and transplant rejection. In this review, the authors discuss the state of the art regarding the status of drug discovery efforts targeting S1P receptors and place emphasis on potential clinical applications.

• Natural Product Sciences
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• v.17 no.4
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• pp.315-320
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• 2011

Routinely applicable HPLC assay procedures for the ganglioside content in various deer antler preparations were established through the creation of a UV-absorbing chromophoric substance - trans-${\alpha},{\beta}$-unsaturated-hexadecene-aldehyde - from the sphingosine moiety in ganglioside molecules by two step chemical reactions. In order to guarantee the assay's accuracy and sensitivity, the HPLC-assay procedure adopted internal reference procedures by mixing cis-${\alpha},{\beta}$-unsaturated-hexadecene aldehyde[V] or cis-3-heptadecene- 1,2-diol[IV] to assay samples. The internal reference compound [IV] or [V] was synthesized in our laboratory starting from mannitol-diacetonide through three or four step organic reactions. This new HPLC-assay procedure was successfully applied to deer antler extracts with good dose-dependent calibration curves at the picomole level of gangliosides.

• IMMUNE NETWORK
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• v.14 no.2
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• pp.100-106
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• 2014

Infection with invasive Shigella species results in intestinal inflammation in humans but no symptoms in adult mice. To investigate why adult mice are resistant to invasive shigellae, 6~8-week-old mice were infected orally with S. flexneri 5a. Shigellae successfully colonized the small and large intestines. Mild cell death was seen but no inflammation. The infected bacteria were cleared 24 hours later. Microarray analysis of infected intestinal tissue showed that several genes that are involved with the sphingosine-1-phosphate (S1P) signaling pathway, a lipid mediator which mediates immune responses, were altered significantly. Shigella infection of a human intestinal cell line modulated host S1P-related genes to reduce S1P levels. In addition, co-administration of S1P with shigellae could induce inflammatory responses in the gut. Here we propose that Shigella species have evasion mechanisms that dampen host inflammatory responses by lowering host S1P levels in the gut of adult mice.

• Biomolecules & Therapeutics
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• v.14 no.1
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• pp.25-29
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• 2006

We tested effects of bioactive lysophospholipids including lysophosphatidic acid (LPA), lysophosphatidylcholine (LPC), sphingosylphosphorylcholine (SPC), and sphingosine I-phosphate (S1P) on membrane potential in C6 glioma cells to understand action mechanism of the lysophospholipids. Membrane potential was estimated by measuring fluorescence change of DiBAC-loaded glioma cells. LPA largely increased membrane potential and the increase was gradually diminished. LPC also increased the membrane potential, however, the increase sustained. SPC induced smaller increase of membrane potential than LPC. SIP was not able to change the membrane potential. We tested effects of suramin and pertussis toxin on lysophospholipid-induced membrane potential increase. However, there wasn't any effect. The membrane potential increase was partially diminished in $Na^+$-free media, suggesting $Na^+$ influx as a component of membrane potential changes. Thus, involvement of $Na^+$ influx in the increase of membrane potential by lysophospholipids and independence of suramin-sensitive GPCRs and pertussis toxin-sensitive G proteins are found in this study.