Division of Endocrinology, Metabolism, and Medical Genetics, Department of Medicine, Medical University of South Carolina, Charleston, SC, USA.
J Lipid Res. 2010 Sep;51(9):2619-28. doi: 10.1194/jlr.M003988. Epub 2010 Jun 3.
Sphingosine-1-phosphate (S1P) is a bioactive lysophospholipid that regulates numerous key cardiovascular functions. High-density lipoproteins (HDLs) are the major plasma lipoprotein carriers of S1P. Fibrinolysis is a physiological process that allows fibrin clot dissolution, and decreased fibrinolytic capacity may result from increased circulating levels of plasminogen activator inhibitor-1 (PAI-1). We examined the effect of S1P associated with HDL subfractions on PAI-1 secretion from 3T3 adipocytes. S1P concentration in HDL3 averaged twice that in HDL2. Incubation of adipocytes with increasing concentrations of S1P in HDL3, but not HDL2, or with S1P complexed to albumin stimulated PAI-I secretion in a concentration-dependent manner. Quantitative RT-PCR revealed that S1P(1-3) are expressed in 3T3 adipocytes, with S1P(2) expressed in the greatest amount. Treatment of adipocytes with the S1P(1) and S1P(3) antagonist VPC23019 did not block PAI-1 secretion. Inhibiting S1P(2) with JTE-013 or reducing the expression of the gene coding for S1P(2) using silencing RNA (siRNA) technology blocked PAI-1 secretion, suggesting that the S1P(2) receptor mediates PAI-1 secretion from adipocytes exposed to HDL3 or S1P. Treatment with the phospholipase C (PLC) inhibitor U73122, the protein kinase C (PKC) inhibitor RO-318425, or the Rho-associated protein kinase (ROCK) inhibitor Y27632 all significantly inhibited HDL3- and S1P-mediated PAI-1 release, suggesting that HDL3- and/or S1P-stimulated PAI-1 secretion from 3T3 cells is mediated by activation of multiple, downstream signaling pathways of S1P(2).
鞘氨醇-1-磷酸（S1P）是一种生物活性溶血磷脂，可调节多种关键的心血管功能。高密度脂蛋白（HDL）是 S1P 的主要血浆脂蛋白载体。纤溶是一种允许纤维蛋白凝块溶解的生理过程，而纤溶能力的降低可能是由于循环中纤溶酶原激活物抑制剂-1（PAI-1）水平升高所致。我们研究了与 HDL 亚组分相关的 S1P 对 3T3 脂肪细胞中 PAI-1 分泌的影响。HDL3 中的 S1P 浓度平均是 HDL2 的两倍。用浓度逐渐增加的 S1P 孵育 HDL3 中的脂肪细胞，但不是 HDL2，或用与白蛋白结合的 S1P 孵育，均可浓度依赖性地刺激 PAI-I 分泌。定量 RT-PCR 显示，3T3 脂肪细胞中表达 S1P(1-3)，其中 S1P(2)表达量最大。用 S1P(1)和 S1P(3)拮抗剂 VPC23019 处理脂肪细胞不能阻断 PAI-1 的分泌。用 S1P(1)和 S1P(3)拮抗剂 VPC23019 处理脂肪细胞不能阻断 PAI-1 的分泌。用 S1P(2)抑制剂 JTE-013 或用沉默 RNA(siRNA)技术降低编码 S1P(2)的基因的表达阻断 PAI-1 的分泌，表明 S1P(2)受体介导暴露于 HDL3 或 S1P 的脂肪细胞中 PAI-1 的分泌。用磷脂酶 C（PLC）抑制剂 U73122、蛋白激酶 C（PKC）抑制剂 RO-318425 或 Rho 相关蛋白激酶（ROCK）抑制剂 Y27632 处理均可显著抑制 HDL3 和 S1P 介导的 PAI-1 释放，表明 HDL3 和/或 S1P 刺激 3T3 细胞中 PAI-1 的分泌是通过 S1P(2)的多个下游信号通路的激活介导的。
