• The Korean Journal of Physiology and Pharmacology
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• v.6 no.3
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• pp.139-142
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• 2002

To examine intracellular signaling of human $S1P_3\;(hS1P_3),$ a sphingosine 1-phosphate (S1P) receptor in plasma membrane, $hS1P_3$ DNA was transfected into RH7777 rat hepatoma cell line, and the inhibition of forskolin-induced cAMP accumulation and activation of MAP kinases by S1P were tested. In $hS1P_3$ transformants, S1P inhibited forskolin-induced activation of adenylyl cyclase activity by about 80% and activated MAP kinases in dose-dependent and pertussis-toxin (PTX) sensitive manners. In oocytes expressing $hS1P_3$ receptor, S1P evoked $Cl^-$ conductance. These data suggested that PTX-sensitive G proteins are involved in $hS1P_3-mediated$ signaling, especially the positive action of S1P in cell proliferation. The potential advantages of rat hepatoma cells for the research of sphingosine 1-phosphate receptor are discussed.

• Biomolecules & Therapeutics
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• v.29 no.4
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• pp.373-383
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• 2021

Atherosclerosis is the deposition of plaque in the main arteries. It is an inflammatory condition involving the accumulation of macrophages and various lipids (low-density lipoprotein [LDL] cholesterol, ceramide, S1P). Moreover, endothelial cells, macrophages, leukocytes, and smooth muscle cells are the major players in the atherogenic process. Sphingolipids are now emerging as important regulators in various pathophysiological processes, including the atherogenic process. Various sphingolipids exist, such as the ceramides, ceramide-1-phosphate, sphingosine, sphinganine, sphingosine-1-phosphate (S1P), sphingomyelin, and hundreds of glycosphingolipids. Among these, ceramides, glycosphingolipids, and S1P play important roles in the atherogenic processes. The atherosclerotic plaque consists of higher amounts of ceramide, glycosphingolipids, and sphingomyelin. The inhibition of the de novo ceramide biosynthesis reduces the development of atherosclerosis. S1P regulates atherogenesis via binding to the S1P receptor (S1PR). Among the five S1PRs (S1PR1-5), S1PR1 and S1PR3 mainly exert anti-atherosclerotic properties. This review mainly focuses on the effects of ceramide and S1P via the S1PR in the development of atherosclerosis. Moreover, it discusses the recent findings and potential therapeutic implications in atherosclerosis.

• Proceedings of the Korean Biophysical Society Conference
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• 2001.06a
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• pp.49-49
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• 2001

Sphingosine 1-phosphate is a metabolite of complex sphingolipids that acts as both a second messenger and as a high-affinity ligand for cell surface receptor. Since the possible involvement of sphingosine 1-phosphate has not been investigated in adipocyte, we examined the response of intracellular calcium ([Ca$^{2＋}$]$_{i}$) and intracellular cAMP ([cAMP]$_{i}$ and the effect of sphingosine 1-phosphate on adipocyte function using rat primary adipocyte.(omitted)ted)

• 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.

• Biomolecules & Therapeutics
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• v.27 no.3
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• pp.318-326
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• 2019

Sphingosine 1-phosphate (S1P) levels are often found to be elevated in serum, bronchoalveolar lavage, and lung tissue of idiopathic pulmonary fibrosis patients and experimental mouse models. Although the roles of sphingosine kinase 1 and S1P receptors have been implicated in fibrosis, the underlying mechanism of fibrosis via Sphingosine 1-phosphate receptor 2 ($S1P_2$) has not been fully investigated. Therefore, in this study, the roles of $S1P_2$ in lung inflammation and fibrosis was investigated by means of a bleomycin-induced lung fibrosis model and lung epithelial cells. Bleomycin was found to induce lung inflammation on day 7 and fibrosis on day 28 of treatment. On the $7^{th}$ day after bleomycin administration, $S1P_2$ deficient mice exhibited significantly less pulmonary inflammation, including cell infiltration and pro-inflammatory cytokine induction, than the wild type mice. On the $28^{th}$ day after bleomycin treatment, severe inflammation and fibrosis were observed in lung tissues from wild type mice, while lung tissues from $S1P_2$ deficient mice showed less inflammation and fibrosis. Increase in TGF-${\beta}1$-induced extracellular matrix accumulation and epithelial-mesenchymal transition were inhibited by JTE-013, a $S1P_2$ antagonist, in A549 lung epithelial cells. Taken together, pro-inflammatory and pro-fibrotic functions of $S1P_2$ were elucidated using a bleomycin-induced fibrosis model. Notably, $S1P_2$ was found to mediate epithelial-mesenchymal transition in fibrotic responses. Therefore, the results of this study indicate that $S1P_2$ could be a promising therapeutic target for the treatment of pulmonary fibrosis.

• Biomolecules & Therapeutics
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• v.25 no.1
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• pp.1-3
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• 2017

• Proceedings of the PSK Conference
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• 2002.04a
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• pp.99.1-99.1
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• 2002

• 대한약리학회:학술대회논문집
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• 2006.10a
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• pp.105.1-105.1
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• 2006

• 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.

• Biomolecules & Therapeutics
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• v.27 no.4
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• pp.373-380
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• 2019

Sphingosine kinase 1 and its product, sphingosine 1-phosphate (S1P), as well as their receptors, have been implicated in inflammatory responses. The functions of receptors $S1P_1$ and $S1P_2$ on cell motility have been investigated. However, the function of $S1P_3$ has been poorly investigated. In this study, the roles of $S1P_3$ on inflammatory response were investigated in primary peritoneal macrophages. $S1P_3$ receptor was induced along with sphingosine kinase 1 by stimulation of lipopolysaccharide (LPS). LPS treatment induced inflammatory genes, such iNOS, COX-2, $IL-1{\beta}$, IL-6 and $TNF-{\alpha}$. TY52156, an antagonist of $S1P_3$ suppressed the induction of inflammatory genes in a concentration dependent manner. Suppression of iNOS and COX-2 induction was further confirmed by western blotting and NO measurement. Suppression of $IL-1{\beta}$ induction was also confirmed by western blotting and ELISA. Caspase 1, which is responsible for $IL-1{\beta}$ production, was similarly induced by LPS and suppressed by TY52156. Therefore, we have shown $S1P_3$ induction in the inflammatory conditions and its pro-inflammatory roles. Targeting $S1P_3$ might be a strategy for regulating inflammatory diseases.