Sphingosine-1-phosphate (S1P) is an important lipid mediator that regulates a diverse range of intracellular cell signaling pathways that are relevant to tissue engineering and regenerative medicine. However, the precise function of S1P in dental pulp stem cells (DPSCs) and its osteogenic differentiation remains unclear. We here investigated the function of S1P/S1P receptor (S1PR)-mediated cellular signaling in the osteogenic differentiation of DPSCs and clarified the fundamental signaling pathway. Our results showed that S1P-treated DPSCs exhibited a low rate of differentiation toward the osteogenic phenotype in association with a marked reduction in osteogenesis-related gene expression and AKT activation. Of note, both S1PR1/S1PR3 and S1PR2 agonists significantly downregulated the expression of osteogenic genes and suppressed AKT activation, resulting in an attenuated osteogenic capacity of DPSCs. Most importantly, an AKT activator completely abrogated the S1P-mediated downregulation of osteoblastic markers and partially prevented S1P-mediated attenuation effects during osteogenesis. Intriguingly, the pro-inflammatory TNF-α cytokine promoted the infiltration of macrophages toward DPSCs and induced S1P production in both DPSCs and macrophages. Our findings indicate that the elevation of S1P under inflammatory conditions suppresses the osteogenic capacity of the DPSCs responsible for regenerative endodontics.
Cell Differentiation ; Cell Proliferation ; Cells, Cultured ; Dental Pulp/metabolism* ; Lysophospholipids ; Osteogenesis ; Proto-Oncogene Proteins c-akt/metabolism* ; Signal Transduction ; Sphingosine/analogs & derivatives* ; Stem Cells

BACKGROUNDThe sphingosine 1-phosphate (S1P) receptors (S1PRs) are a group of G protein-coupled receptors expressed on the surface of lymphocytes. The interaction between S1P and S1PRs plays a significant role in the migration and distribution of lymphocytes.

OBJECTIVETo investigate the influence of S1PR5 defect on the lymphocytes distribution in mice.

METHODSThe distribution of different subsets of lymphocyte in the mice with S1PR5 defect was examined by flow cytometry.

RESULTSCompared with wild type mice, the number of NK cells in the peripheral blood (PB) and spleen (SP) from the mice with S1PR5 defect decreased very significantly 〔PB: 6.4±0.45% vs 2.2±0.47(P<0.01,n=3)；SP: 3.0±0.91% vs 0.68±0.14%(P<0.05,n=3)〕. However, the NK cell number in the bone marrow (BM) and lymphonodes (LN) of the mice with S1PR5 defect increased very significantly 〔BM: 0.97±0.20 % vs 2.6±0.35% (P<0.01, n=3); LN: 0.35±0.16% vs 1.7±0.15% (P<0.01, n=3)〕. The percentages of CD3(+) lymphocyte in peripheral blood, spleen and lymph node were not statistically significantly different between these 2 types of mice 〔PB: 17.3±7.9% vs 17.0±4.6% (P>0.05, n=3); SP: 33.0±6.0% vs 27.4±1.8% (P>0.05, n=3); LN: 42.3±10.7% vs 51.2±2.7% (P>0.05, n=3)〕.

CONCLUSIONS1PR5 defect can significantly influence the NK cell distribution.

Animals ; Bone Marrow ; Cell Count ; Flow Cytometry ; Lymphocytes ; Lysophospholipids ; Mice ; Receptors, Lysosphingolipid ; Sphingosine ; analogs & derivatives

Sphingolipids, especially ceramide and S1P, are structural components of biological membranes and bioactive molecules which participate in diverse cellular activities such as cell division, differentiation, gene expression and apoptosis. Emerging evidence demonstrates the role of sphingolipids in hepatocellular death, which contributes to the progression of several liver diseases including ischaemia-reperfusion liver injury, steatohepatitis or hepatocarcinogenesis. Furthermore, some data indicate that the accumulation of some sphingolipids contributes to the hepatic dysfunctions. Hence, understanding of sphingolipid may open up a novel therapeutic avenue to liver diseases. This review focuses on the progress in the sphingolipid metabolic pathway with a focus on hepatic diseases and drugs targeting the sphingolipid pathway.
Apoptosis ; Ceramides ; metabolism ; Fatty Liver ; metabolism ; physiopathology ; Humans ; Liver Diseases ; metabolism ; physiopathology ; Lysophospholipids ; metabolism ; Reperfusion Injury ; metabolism ; physiopathology ; Sphingolipids ; metabolism ; Sphingosine ; analogs & derivatives ; metabolism

OBJECTIVE: To explore the exact mechanisms of programmed cell death (PCD) induced by Type II anti-CD20 mAb in CD20+ non-Hodgkin lymphoma (NHL) cells, and to provide theoretical basis for anti-tumor ability of new CD20 mAb.
 METHODS: After incubation with Rituximab (a Type I anti-CD20 mAb) and Tositumomab (a Type II anti-CD20 mAb), Raji cells were stained by annexin V & propidium iodide (PI). The ratio of programmed death cells were measured by two channel flow cytometry (FCM). Before the treatment of anti-CD20 mAbs, Raji cells was incubated with a caspase inhibitor carbobenzoxy-valyl-alanyl-aspartyl-[O-methyl]- fluoromethylketone (Z-VAD-FMK) and a dihydroceramide synthase inhibitor fumonisin B1 (FB1) for 30 minutes to assess their inhibitory effect on PCD. High performance liquid chromatography (HPLC) was utilized to compare the ratio of programmed death cells between the pretreatment group (treated by Rituximab and Tositumomab) and the non-pretreatment group. The anti-CD20 mAbs-treated Raji cells were collected, and the ceramide levels in the Raji cells in the different pretreatment groups were also examined by HPLC, and the inhibitory effect of FB1 on the changes of ceramide levels in the Raji cells was measured. The Raji cells were incubated with different concentration C2-ceramide, C2-Ceramide-induced PCD was also evaluated by annexin V & PI staining after 16 hours. 
 RESULTS: Tositumomab (10 µg/mL) but not Rituximab (10 µg/mL) can induce significant PCD (28.6±4.2)% in Raji cells, with significant difference (t=26.48, P<0.01), which cannot be blocked by Z-VAD-FMK with a concentration range from 10 to 30 µmol/L (F=3.01, P>0.05). The cellular ceramide levels in Raji cells were significantly elevated after the treatment of Tositumomab (t=28.48, P<0.01). C2-ceramide can significantly induce PCD in Raji cells in a dose-dependent manner with a concentration range from 5 to 40 µmol/L (F=2.71, P>0.05). The dihydroceramide synthase inhibitor FB1 can significantly inhibit the elevated cellular ceramide levels (F=20.18, P<0.01) and cell programmed death induced by Tositumomab (F=17.02, P<0.01).
 CONCLUSION Type II but not Type I anti-CD20 mAbs can induce caspase independent PCD in CD20+ NHL cells through the elevation of cellular ceramide levels. The PCD is not associated with classic caspase pathway.
Amino Acid Chloromethyl Ketones ; Apoptosis ; drug effects ; Cell Line, Tumor ; drug effects ; Humans ; Lymphoma, Non-Hodgkin ; Rituximab ; pharmacology ; Sphingosine ; analogs & derivatives ; pharmacology

OBJECTIVEDiabetic nephropathy (DN) is the major cause of end-stage renal disease worldwide and its prevalence continues to increase. Currently, therapies for DN provide only partial renoprotection; hence new targets for therapeutic intervention need to be identified. In this review, we summarized the new target, sphingosine kinase-1/sphingosine 1-phosphate (SphK1/S1P) pathway, explored its potential therapeutic role in the prevention and treatment of DN.

DATA SOURCESMost relevant articles were mainly identified by searching PubMed in English.

STUDY SELECTIONMainly original articles and critical review articles by major pioneer investigators in this field were selected to be reviewed.

RESULTSSphK1/S1P pathway can be activated by hyperglycemia, advanced glycation end products, and many pro-inflammatory cytokines, which leads to fibronectin, transforming growth factor-β1 up-regulation and AP-1 activation. And then it could promote glomerular mesangial cells proliferation and extracellular matrix accumulation, mediating the initiation and progression of diabetic renal fibrosis.

CONCLUSIONSSphK1/S1P pathway is closely correlated with the pathogenesis of DN. The results suggest that SphK1/S1P pathway as a new target for clinically improving DN in future is of great prospect.

Diabetic Nephropathies ; enzymology ; metabolism ; Extracellular Matrix ; metabolism ; Humans ; Lysophospholipids ; metabolism ; Phosphotransferases (Alcohol Group Acceptor) ; metabolism ; Signal Transduction ; Sphingosine ; analogs & derivatives ; metabolism

Sphingosine-1-phosphate (S1P) has been demonstrated to be a mediator and marker of heart diseases. We hypothesized that the expression of S1P receptors is involved in the S1P-mediated cardioprotection in vivo and may serve as a biomarker of ischemic heart disease. In vivo models of myocardial ischemia (MI) and ischemia-reperfusion (IR) were established by ligation of the left anterior descending artery (LAD) of rat heart, the mRNA expressions of S1PR1-3 were detected using real time PCR at different time intervals after ischemia (LAD for 15 min, 30 min, and 1 h) and IR. The results showed that mRNA expression of S1PR3, but not S1PR1 and S1PR2, increased greatly after IR. No statistical difference was found in any of the three S1P receptors after MI within 1 h. Regarding the studies of lipid concentration changes in myocardiopathy, we conclude that S1P receptors are not early response biomarkers for MI. There are different mechanisms when S1P plays a protection role in heart during MI and IR. The cooperation of lipid content and S1P receptor expression appears to form a regulation network during MI and IR.
Animals ; Lysophospholipids ; physiology ; Myocardial Reperfusion Injury ; physiopathology ; Rats ; Receptors, Lysosphingolipid ; physiology ; Sphingosine ; analogs & derivatives ; physiology

Syl948 is a synthesized selective S1P1 agonist with novel structure. HTRF-IP1 test indicated that Syl948-P, the active form of Syl948 in vitro, has strong activity against S1P1 (EC50: 83 +/- 16 nmol x L(-1)), but its effect on S1P3 was very weak (EC50: 1 026 +/- 90 nmol x L(-1)). In SD rats, oral administration of Syl948 10 mg x kg(-1) significantly decreased the peripheral blood lymphocytes (PBL), with the maximal PBL inhibition rate of 63%, which was as similar as equal dose of fingolimod (FTY720). Oral administration of Syl948 10 mg x kg(-1) had no effect on heart rate of SD rats, which was better than FTY720. Daily oral administration with Syl948 (2 or 4 mg x kg(-1)) significantly prolonged the survival time of the allografts of skin slice on mice. In summary, the above results demonstrated that Syl948 has great selectivity in vitro and good activity in vivo, which indicated its potential use as an anti-rejection drug in skin transplantation.
Animals ; Fingolimod Hydrochloride ; Graft Survival ; drug effects ; Immunosuppressive Agents ; pharmacology ; Lymphocytes ; drug effects ; Mice ; Propylene Glycols ; pharmacology ; Rats ; Receptors, Lysosphingolipid ; agonists ; Skin Transplantation ; Sphingosine ; analogs & derivatives ; pharmacology ; Transplantation, Homologous

This study was purpose to investigate the role of reactive oxygen species (ROS) in apoptosis and autophagy induced by FTY720 in multiple myeloma cell line U266. U266 cells were treated by different concentrations of FTY720 for 24 h, the apoptotic rates were detected by flow cytometry, and the expression of LC3B was detected by Western blot. The results indicated that apoptosis and autophagy were induced by FTY720 in U266 cells. Autophagy induced by FTY720 could lead to cell death. Bafilomycin A1, the inhibitor of autophagy, could enhance the cell viability in U266 cells treated with FTY720. NAC or Tiron, ROS scavenger, could decrease the FTY720 induced apoptosis and the expression of LC3B-II was reduced in combination of FTY720 with NAC or Tiron as compared with treatment with FTY720 only. It is concluded that FTY720 can induce U266 cell apoptosis and autophagy. ROS is the mediator that regulates both the apoptosis and autophagy in multiple myeloma cells.
1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt ; Apoptosis ; drug effects ; Autophagy ; drug effects ; Cell Line, Tumor ; Fingolimod Hydrochloride ; Humans ; Macrolides ; Microtubule-Associated Proteins ; metabolism ; Multiple Myeloma ; metabolism ; pathology ; Propylene Glycols ; pharmacology ; Reactive Oxygen Species ; metabolism ; Sphingosine ; analogs & derivatives ; pharmacology

OBJECTIVETo investigate the effects of sphingosine kinase 1 (SphK1) on the proliferation, migration and invasion of human colon cancer LoVo cells, and to explore the related mechanisms.

METHODSHuman colon cancer LoVo cells were divided into three groups: phorbol 12-myristate 13-acetate (PMA) was used to induce the activation of SphK1 in the PMA group, N,N-dimethylsphingosine (DMS) used to suppress the activity of SphK1 in DMS group, and the cells treated with equal amount of 0.9 % NaCl instead of drugs served as the control group. The activity of SphK1 was assayed by autoradiography, the cell proliferation was assessed by MTT assay, cell migration and invasion were examined by Boyden chamber assay, concentrations of sICAM-1 and sVCAM-1 were assayed by ELISA, and RT-PCR and Western blot were used to evaluate the mRNA and protein expression in the cells.

RESULTSThe activity of SphK1 was efficiently induced by PMA and significantly suppressed by DMS. PMA induced cell proliferation in a time- and dose-dependent manner. On the contrast, DMS suppressed cell proliferation in a time- and dose-dependent manner. After treating with PMA, the number of migrating and invasing cells were increased to 143.36 ± 8.73 and 118.46 ± 6.25, significantly higher than those of the control group (75.48 ± 6.12 and 64.19 ± 5.36). After treating with DMS, the number of migrating and invasing cells were decreased to 38.57 ± 3.24 and 32.48 ± 4.27, significantly lower than those of the control group (P < 0.01). The relative expression levels of FAK, ICAM-1 and VCAM-1 mRNA in the PMA group were 0.82 ± 0.06, 0.74 ± 0.05 and 0.89 ± 0.09, and those in the DMS group were 0.23 ± 0.02, 0.26 ± 0.03 and 0.37 ± 0.04, with significant differences between the PMA, DMS and control groups (P < 0.01). Compared with the control group, the relative expression levels of FAK and p-FAK proteins in the PMA group (0.52 ± 0.06 and 0.51 ± 0.06) were significantly elevated, and those of the DMS group (0.20 ± 0.03 and 0.09 ± 0.02) were significantly decreased. In addition, the concentrations of sICAM-1 and sVCAM-1 were significantly elevated with the activation of SphK1. On the contrary, those of the DMS group were significantly reduced with the suppression of SphK1 (Both P < 0.01).

CONCLUSIONSSphK1 may enhance the proliferation, migration and invasion of colon cancer LoVo cells through activating FAK pathway and up-regulating the expression of ICAM-1 and VCAM-1.

Cell Line, Tumor ; Cell Movement ; drug effects ; Cell Proliferation ; drug effects ; Colonic Neoplasms ; enzymology ; metabolism ; pathology ; Dose-Response Relationship, Drug ; Enzyme Inhibitors ; pharmacology ; Focal Adhesion Kinase 1 ; genetics ; metabolism ; Humans ; Intercellular Adhesion Molecule-1 ; genetics ; metabolism ; Neoplasm Invasiveness ; Phosphorylation ; drug effects ; Phosphotransferases (Alcohol Group Acceptor) ; metabolism ; RNA, Messenger ; metabolism ; Signal Transduction ; Sphingosine ; analogs & derivatives ; pharmacology ; Tetradecanoylphorbol Acetate ; pharmacology ; Vascular Cell Adhesion Molecule-1 ; genetics ; metabolism

Sphingolipids as an important regulator play a critical role in the cell biological functions. Among them, ceramide (Cer) and sphingosine (Sph) induce apoptosis and inhibit cell proliferation; on the contrary sphingosine 1-phosphate (S1P) promotes cell survival and proliferation. The balance between ceramide/sphingosine and S1P forms a so-called "sphingolipid-rheostat", which decides the cell fate. Sphingosine kinases, which catalyze the phosphorylation of sphingosine to S1P, are critical regulators of this balance. Here, we review the role of sphingosine kinase 1 (SphK1) in regulating fundamental biological processes and tumorigenesis and the potential of SphK1 as a new target for cancer therapeutics.
Amino Alcohols ; pharmacology ; Animals ; Apoptosis ; drug effects ; Cell Movement ; drug effects ; Cell Proliferation ; drug effects ; Ceramides ; metabolism ; Enzyme Activation ; Enzyme Inhibitors ; pharmacology ; Humans ; Lysophospholipids ; metabolism ; Neoplasms ; metabolism ; pathology ; Neovascularization, Pathologic ; Phosphorylation ; Phosphotransferases (Alcohol Group Acceptor) ; antagonists & inhibitors ; metabolism ; Sphingosine ; analogs & derivatives ; metabolism ; Thiazoles ; pharmacology