1-磷酸鞘氨醇受体信号在造血干/祖细胞迁移中的作用

Role of sphingosine 1-phosphate receptor signaling in hematopoietic stem/progenitor cell transmigration

目的探讨1-磷酸鞘氨醇受体(S1PRs)在CD34+造血干/祖细胞迁移中的作用。方法用密度梯度离心法分离脐血CD34+细胞,悬浮于transwell培养板的上层,在不同组细胞中分别给予FTY720预处理、含或不含百日咳毒素(PTX)或CXCR4单抗,下层添加SDF-1,流式细胞仪检测迁移细胞数,计算迁移率。同时用逆转录-聚合酶链反应(RT-PCR)的方法检测迁移前后CD34+细胞的S1PRs的表达情况。另用FTY720处理脐血CD34+细胞,在不同时间点(1、8、16h)用流式细胞仪检测CD49d(VLA-4)、CD11a(LFA-1)、CD62L(L-selectin)的表达。结果FTY720不影响CD34+细胞的自发迁移,但明显促进SDF-1诱导的CD34+细胞迁移(15.262.14vs28.642.37),这种作用可以被PTX和CXCR4单抗完全阻断。新鲜分离的脐血CD34+细胞表达S1P1-5,但在FTY720和SDF-1作用下发生迁移的CD34+细胞只表达S1P1、S1P3,S1P4。CD34+细胞在FTY720作用下各个时间点测得的黏附分子表达水平无差别。结论S1PRs可能与CD34+细胞快速迁移有关,激活S1PRs能够增加SDF-1对CD34+细胞的趋化作用,这种作用是通过CXCR4介导的,信号传递偶联PTX敏感的Gi蛋白受体家族。表达特定S1PRs的CD34+细胞才容易发生快速迁移。FTY720不改变CD34+细胞黏附分子的表达。

Objective To determine the role of sphingosine 1-phosphate receptor （S 1PRs ） signaling in CD34^＋ hematopoietic stem/progenitor cell transmigration. Methods CD34^＋ cells were separated by Ficoll density gradient centrifugation and incubated in DMEM medium with 10% fetal calf serum. The cells were pretreated by FTY720, with or without pertussis toxin （PTX） and antiCXCR4 mAb in the medium, followed by addition of 100 ng/ml SDF-1 into the lower chamber of a Costar 24-well transwell. The migrated cells were counted using FACS and the migrating rates were determined. The expressions of sphingosine 1-phosphate receptors were analyzed in CD34^＋ cells before and after the transmigration by reverse transcriptase- polymerase chain reaction （RT-PCR）. Cord blood CD34^＋ cells were treated with or without FTY720 （10.7 mol/L）, and the expressions of CD49d （VLA-4）, CD1 la （LFA-1）, and CD62L （L-selectin） were analyzed at 1, 8, and 16 h after the treatment. Results While FTY720 did not affect spontaneous migration, a substantial increase of SDF-1-induced transmigration was observed in the presence of FTY720 （15.26 2.14 to 28.64 2.37）. The FTY720-enhanced transmigration was completely blocked by addition of PTX or antiCXCR4 mAb. S1p1-5 was expressed in fresh isolated cord blood CD34^＋ cells. The migrating cells stimulated by FTY720 and SDF-1 only expressed S1P1, S1P3, and S1P4. The expressions of CD49d, CD11a and CD62L on CD34^＋ cells treated with FTY720 remained unchanged at the selected time points as compared with the control. Conclusions S1PRs are involved the transmigration ofCD34^＋ cells. The activation of S1PRs results in increased chemotactic response ofCD34^＋ to SDF-1. These effects are mediated through CXCR4 and PTX-sensitive Gi proteins. Only the CD34^＋ cells expressing the specific receptors can rapidly transmigrate. The activation of the S1PRs does not affect the expressions of the adhesion molecules on cord blood CD34^＋ cells.