Simón María V, Prado Spalm Facundo H, Politi Luis E, Rotstein Nora P
Invest Ophthalmol Vis Sci. 2015 Sep;56(10):5808-15. doi: 10.1167/iovs.14-16195.
Migration of Müller glial cells is enhanced in proliferative retinopathies, but the mechanisms involved are ill defined. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid synthesized by sphingosine kinase (SphK), which promotes proliferation, migration, and inflammation, acting as an intracellular mediator and activating a family of membrane receptors (S1PRs). We investigated whether S1P regulated glial migration.
Müller glial cell cultures from rat retinas were supplemented with 5 μM S1P, and migration was evaluated by scratch-wound assays. Cultures were treated with SphK inhibitor 2 (SphKI 2), a SphK1 inhibitor, or with W146 and BML-241, S1P1 and S1P3 antagonists, respectively, to investigate whether Müller glial cells synthesized S1P and S1P-activated S1PRs to stimulate migration. The effects of LY294002, U0126, and SB203580, which are phosphatidylinositol-3 kinase (PI3K), extracellular signal regulated kinase/mitogen-activated protein kinase (ERK/MAPK), and p38 MAPK inhibitors, respectively, on glial migration were determined.
Sphingosine-1-phosphate addition prompted the formation of lamellipodia and enhanced glial migration. SphKI 2 almost completely prevented glial migration in controls; BML-241 inhibited this migration both in controls and in S1P-supplemented cultures, whereas W146 had no significant effect. Pretreatment with LY294002 and U0126 abrogated glial migration; SB203580 decreased it partially, although not significantly.
Our results suggest that Müller glial cells synthesize S1P, which signals through S1P3 and the PI3K and ERK/MAPK pathways to induce glial migration. As a whole, our data point to a central role for S1P in controlling glial cell motility. Because deregulation of this process is involved in several retinal pathologies, S1P signaling emerges as a potential tool for treating these diseases.
在增殖性视网膜病变中，Müller胶质细胞的迁移增强，但相关机制尚不明确。鞘氨醇-1-磷酸（S1P）是一种由鞘氨醇激酶（SphK）合成的生物活性鞘脂，它可促进增殖、迁移和炎症反应，作为细胞内介质并激活一族膜受体（S1PRs）。我们研究了S1P是否调节胶质细胞迁移。
用5μM S1P处理大鼠视网膜的Müller胶质细胞培养物，通过划痕试验评估迁移情况。分别用鞘氨醇激酶抑制剂2（SphKI 2，一种SphK1抑制剂）、W146和BML-241（分别为S1P1和S1P3拮抗剂）处理培养物，以研究Müller胶质细胞是否合成S1P以及S1P激活的S1PRs是否刺激迁移。分别测定磷脂酰肌醇-3激酶（PI3K）抑制剂LY294002、细胞外信号调节激酶/丝裂原活化蛋白激酶（ERK/MAPK）抑制剂U0126和p38 MAPK抑制剂SB203580对胶质细胞迁移的影响。
添加鞘氨醇-1-磷酸促使板状伪足形成并增强胶质细胞迁移。SphKI 2几乎完全阻止了对照组中的胶质细胞迁移；BML-241在对照组和补充S1P的培养物中均抑制了这种迁移，而W146没有显著影响。用LY294002和U0126预处理消除了胶质细胞迁移；SB203580虽有部分降低但不显著。
我们的结果表明，Müller胶质细胞合成S1P，其通过S1P3以及PI3K和ERK/MAPK途径发出信号以诱导胶质细胞迁移。总体而言，我们的数据表明S1P在控制胶质细胞运动中起核心作用。由于这一过程的失调与多种视网膜病变有关，S1P信号传导成为治疗这些疾病的潜在工具。
