Sphingosine 1-phosphate receptors mediate the lipid-induced cAMP accumulation through cyclooxygenase-2/prostaglandin I2 pathway in human coronary artery smooth muscle cells
Sphingosine 1-phosphate receptors mediate the lipid-induced cAMP accumulation through cyclooxygenase-2/prostaglandin I2 pathway in human coronary artery smooth muscle cells
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DOI：
10.1124/mol.104.004317
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发表时间：
2005-04-01
影响因子：
3.6
通讯作者：
Okajima, F
中科院分区：
文献类型：
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作者：
Damirin, A;Tomura, H;Okajima, F
鞘氨醇1-磷酸（S1P）已被证明通过细胞外特异性受体或细胞内机制发挥多种生物反应。在本研究中，我们表征了s1p诱导的人冠状动脉平滑肌细胞（CASMCs） cAMP积累的信号通路。S1P诱导双相cAMP积累，包括短期和短暂反应（在2.5 min达到峰值）和后期和持续反应（类似于4-6 h）。cAMP的后期积累与环氧合酶-2蛋白表达的增加平行，并被环氧合酶-2特异性抑制剂N-[2-（环己氧基）-4-硝基苯基]-甲烷磺酰胺（NS398）抑制。我们惊讶地发现，即使在环氧合酶-2蛋白表达尚未增加的情况下，环氧合酶-2抑制剂也能抑制短期cAMP积累。更有趣的是，短期cAMP积累也完全被百日咳毒素（一种G（i/o）蛋白抑制剂）所抑制。JTE-013是一种S1P(2)受体特异性拮抗剂，可抑制S1P诱导的cAMP积累。此外，靶向S1P(2)受体的小干扰rna显著抑制了S1P诱导的cAMP积累。cAMP反应也被磷脂酶C、细胞外信号调节激酶途径和胞质磷脂酶A的特异性抑制剂所抑制(2)。S1P实际上激活了这些酶的活性，刺激了前列腺素I-2 （PGI(2)）的合成。最后，外源施用花生四烯酸和PGI(2)诱导cAMP积累的程度与S1P相似。综上所述，S1P通过S1P受体诱导cAMP积累，包括S1P(2)受体和G（i/o）蛋白介导的细胞内信号通路的刺激，包括环氧化酶-2依赖性PGI(2)的合成。
Sphingosine 1-phosphate (S1P) has been shown to exert a variety of biological responses through extracellular specific receptors or intracellular mechanisms. In the present study, we characterized a signaling pathway of S1P-induced cAMP accumulation in human coronary artery smooth muscle cells (CASMCs). S1P induced biphasic cAMP accumulation composed of a short-term and transient response ( a peak at 2.5 min) and a late and sustained response (similar to 4-6 h). The late phase of cAMP accumulation was parallel to the increment of cyclooxygenase-2 protein expression and was inhibited by N-[2-( cyclohexyloxyl)-4-nitrophenyl]-methane sulfonamide (NS398), a cyclooxygenase-2-specific inhibitor. We were surprised to find that the cyclooxygenase-2 inhibitor also inhibited short-term cAMP accumulation even when cyclooxygenase-2 protein expression was not yet increased. More interestingly, the short-term cAMP accumulation was also completely inhibited by pertussis toxin, an inhibitor of G(i/o) proteins. JTE-013, a specific antagonist for S1P(2) receptors, inhibited the S1P-induced cAMP accumulation. Furthermore, small interfering RNAs targeted for S1P(2) receptors significantly inhibited the S1P-induced cAMP accumulation. The cAMP response was also inhibited by specific inhibitors for phospholipase C, extracellular signal-regulated kinase pathways, and cytosolic phospholipase A(2). S1P actually activated these enzyme activities and stimulated prostaglandin I-2 (PGI(2)) synthesis. Finally, exogenously applied arachidonic acid and PGI(2) induced cAMP accumulation to a similar extent as S1P. In conclusion, S1P induced cAMP accumulation through S1P receptors, including S1P(2) receptor and G(i/o) protein-mediated stimulation of intracellular signaling pathways involving cyclooxygenase-2-dependent PGI(2) synthesis.