[Role and related mechanism of S1P/S1P1 signal pathway during post conditioning of hypertrophic cardiomyocytes].

ABSTRACT

OBJECTIVE: To study the role and mechanism of sphingosine-1-phosphate (S1P)/ sphingosine-1-phosphate receptor 1(S1P1) signal pathway during post conditioning of hypertrophic cardiomyocytes. METHODS: Neonatal rat cardiomyocytes were isolated and cultured, then stimulated by norepinephrine (NE) to induce cardiomyocytes hypertrophy. Using tri-gas incubator to create hypoxia and reoxygenation enviroment to mimic ischemia-reperfusion and postconditioning. Hypertrophic cardiomyoctyes were divided into five groups according to the presence or absence of various drugs and postconditiong and relevant signal pathways changes were detected (1) IPost group (hypoxia+ postconditioning); (2) IPost+ S1P group (cells were pretreated with S1P (1 µmol/L) for 2 h before IPost); (3) IPost+ W-146+ S1P group (cells in IPost+ W-146+ S1P group were pretreated with S1P1 inhibitor W-146 (0.4 µmol/L) for 20 min); (4) IPost+ PD98059+ S1P group (cells in IPost+ S1P group were pretreated with MAPK antagonist PD98059 (125 µmol/L) for 20 min); (5) IPost+ LY-294002+ S1P group (cells in IPost+ S1P group were pretreated with PI3K antagonist LY294002 (0.1 µmol/L) for 20 min). Apoptosis was detected by flow cytometry and protein expression of relevant signal pathways were detected by Western blot. RESULTS: (1)Apoptosis rate was significantly increased in hypoxia/reoxygenation (27.90±4.49)% group compared with normal control group (7.97±2.18)%, which could be significantly reduced in IPost group (15.90±1.77)% (all P<0.05). (2)Apoptosis rate and caspase-3 expression were both significantly lower in IPost+ S1P and IPost+ S1P+ LY-294002 groups than in IPost and IPost+ S1P+ W-146 and IPost+ S1P+ PD98059 group (all P<0.05). (3)p-ERK1/2 expression was significantly higher in IPost+ S1P and IPost+ S1P+ LY-294002 group than in IPost and IPost+ S1P+ W-146 group and IPost+ S1P+ PD98059 group (all P<0.05) while p-Akt expression was similar among IPost, IPost+ S1P+ W-146 and IPost+ S1P+ PD98059 groups. p-ERK1/2 and p-Akt levels in IPost+ S1P+ W-146 group and IPost+ S1P+ PD98059 were similar as in IPost group. CONCLUSIONS: S1P can play protective role on NE induced cardiomyocytes hypertrophy during post conditioning through downregulating caspase-3 expression and reducing apoptosis rate via targeting S1P1 and activating ERK1/2 signal pathway.