Figure 1

Time-dependent changes in mRNA expression of genes involved in the S1P signaling axis. (a) Mice (n = 41) we subjected to 45 min MCAo and were sacrificed at different time points: immediately without reperfusion (time 0) (n = 6) or at 1 h (n = 6), 3 h (n = 5), 6 h (n = 4), 16 h (n = 5), 24 h (n = 6), 4 days (n = 4), or 7 days (n = 5) after reperfusion. mRNA expression of the genes encoding for S1P receptors S1P1, S1P2, S1P3, S1P4 and S1P5, and for the kinases generating S1P, Sphk1 and Sphk2 in the ipsilateral (ischemic) hemisphere were assessed. Results are expressed as fold versus non-ischemic control brain tissue. S1P1, S1P3 and S1P4 mRNAs increased from 16 h of reperfusion, peaking after 4 days. S1P2 mRNA did not changed until day 4 and 7, whereas increases in S1P5 mRNA were not statistically significant. Sphk1 mRNA was strongly upregulated, with increases already detected at 3 h of reperfusion, peaking at 24 h, and then declining. In contrast, the mRNA expression of Sphk2 was rather stable and only showed a small tendency to increase progressively and reached statistically significant differences versus control at day 7. Kruskal-Wallis test followed by Dunn’s test. *p < 0.05, **p < 0.01 vs. time 0. (b) The expression of Sphk1 and Sphk2 mRNA was studied 24 h post-ischemia in the ipsilateral (Ipsi) and contralateral (Contra) hemispheres of an independent group of wild type mice (WT) and Rag2^−/− mice 24 h post-ischemia (n = 4 per group). The increase in Sphk1 mRNA induced by ischemia did not differ between genotypes (Two-way ANOVA, genotype effect p = 0.402, hemisphere effect p < 0.001, interaction p = 0.614). SphK2 mRNA expression did not change between genotypes. Values are expressed as fold versus wild type control.