Sphingosine-1-phosphate receptor 2 mediates endothelial cells dysfunction by PI3K-Akt pathway under high glucose condition.

Endothelial dysfunction is believed the early stage of development of diabetic cardiovascular complications. Sphingosine-1-phosphate (S1P) regulates various biological activities by binding to sphingosine-1-phosphate receptors (S1PRs) including S1PR1-S1PR5. In the present study, the role of S1P receptors in S1P-induced human coronary artery endothelial cells (HCAECs) dysfunction under high glucose condition was investigated and the underlying mechanism was explored. S1PR1-S1PR5 mRNA levels were detected by quantitative Real-time PCR. NO level and polymorphonuclear neutrophils (PMN)-endothelial cells adhesion were measured by nitrate reductase and myeloperoxidase colorimetric method, respectively. Protein levels of endothelial nitric oxide synthase (eNOS), vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1(ICAM-1), phosphatidylinositol 3-kinase (PI3K) and Akt were measured by Western blot analysis. S1PR2 were found the predominant S1P receptor expressed in HCAECs exposed to high glucose. NO level and eNOS activity were remarkably decreased, while PMN adhesion, VCAM-1 and ICAM-1 protein levels were increased significantly by S1P treatment in HCAECs exposed to high glucose and normal glucose. Blockage of S1PR2 with specific antagonist JTE-013 and small interfering RNA (siRNA) resulted in enhanced NO level and eNOS activity as well as decreased PMN adhesion, reduced protein levels of VCAM-1 and ICAM-1 induced by S1P. Furthermore, Phosphor-PI3K and phosphor-Akt level were markedly increased by S1PR2 blockade in S1P-treated cells exposed to high glucose, which were suppressed by PI3K inhibitor wortmannin. In conclusion, S1P/S1PR2 mediated endothelial dysfunction partly by inhibiting PI3K/Akt signaling pathway under high glucose condition. S1PR2 blockage could ameliorate endothelial dysfunction which might provide a potential therapeutic strategy for diabetic vascular complications.

Liu W ，Liu B ，Liu S ，Zhang J ，Lin S ... -  《-》

ApoA-I/SR-BI modulates S1P/S1PR2-mediated inflammation through the PI3K/Akt signaling pathway in HUVECs.

Ren K ，Lu YJ ，Mo ZC ，-Liu X ，Tang ZL ，Jiang Y ，Peng XS ，Li L ，Zhang QH ，Yi GH ... -  《-》

Sphingosine-1-phosphate receptor 2 protects against anaphylactic shock through suppression of endothelial nitric oxide synthase in mice.

Sphingosine-1-phosphate receptor 2 (S1P(2)) is expressed in vascular endothelial cells (ECs). However, the role of S1P(2) in vascular barrier integrity and anaphylaxis is not well understood. Endothelial nitric oxide synthase (eNOS) generates nitric oxide to mediate vascular leakage, compromising survival in patients with anaphylaxis. We recently observed that endothelial S1P(2) inhibits Akt, an activating kinase of eNOS. We tested the hypothesis that endothelial S1P(2) might suppress eNOS, exerting a protective effect against endothelial barrier disruption and anaphylaxis. Mice deficient in S1P(2) and eNOS underwent antigen challenge or platelet-activating factor (PAF) injection. Analyses were performed to examine vascular permeability and the underlying mechanisms. S1pr2 deletion augmented vascular leakage and lethality after either antigen challenge or PAF injection. PAF injection induced activation of Akt and eNOS in the aortas and lungs of S1pr2-null mice, which were augmented compared with values seen in wild-type mice. Consistently, PAF-induced increase in cyclic guanosine monophosphate levels in the aorta was enhanced in S1pr-null mice. Genetic Nos3 deletion or pharmacologic eNOS blockade protected S1pr2-null mice from aggravation of barrier disruption after antigen challenge and PAF injection. ECs isolated from S1pr2-null mice exhibited greater stimulation of Akt and eNOS, with enhanced nitric oxide production in response to sphingosine-1-phosphate or PAF, compared with that seen in wild-type ECs. Moreover, S1pr2-deficient ECs showed more severe disassembly of adherens junctions with augmented S-nitrosylation of β-catenin in response to PAF, which was restored by pharmacologic eNOS blockade. S1P(2) diminishes harmful robust eNOS stimulation and thereby attenuates vascular barrier disruption, suggesting potential usefulness of S1P(2) agonists as novel therapeutic agents for anaphylaxis.

Cui H ，Okamoto Y ，Yoshioka K ，Du W ，Takuwa N ，Zhang W ，Asano M ，Shibamoto T ，Takuwa Y ... -  《-》

Apolipoprotein M and sphingosine-1-phosphate complex alleviates TNF-α-induced endothelial cell injury and inflammation through PI3K/AKT signaling pathway.

Liu Y ，Tie L 《BMC Cardiovascular Disorders》

Sphingosine-1-Phosphate Improves the Biological Features of Mouse Bone Marrow-Derived EPCs Partially through PI3K/AKT/eNOS/NO Pathway.

Wang X ，Zhan E ，Lu G ，Mu Q ，Zhang T ，Yang N ... -  《MOLECULES》