地塞米松影响小鼠胸腺细胞c-Myc表达以及凋亡研究

The c-Myc expression and apoptosis of mouse thymocytes treated with dexamethasone

目的 :研究在地塞米松 (DEX)诱导的小鼠胸腺细胞凋亡过程中c -Myc信号变化特点及其与下游caspase - 3变化的相关性 ,以进一步探讨c -Myc在小鼠胸腺细胞凋亡过程中的作用机制。方法 :以终浓度 1μmol/L地塞米松诱导小鼠胸腺细胞凋亡 ,通过AnnexinV -FITC/PI双染流式细胞术测定 30min、3h、6h和 9h凋亡和坏死细胞比率 ,在 6h时点电镜观察细胞形态 ,利用SDS -PAGE及Westernblot检测 0min、30min、1h和 3h细胞内c -Myc和caspase - 3信号变化特点。结果 :在 1μmol/LDEX诱导下 ,小鼠胸腺细胞在 30min、3h、6h和 9h凋亡比率分别为(5 70± 0 4 6 ) %、(35 79± 1 13) %、(5 0 6 1± 2 15 ) %和 (35 5 2± 1 6 6 ) % ,对照组分别为 (5 97± 0 2 5 ) %、(10 2 0±0 71) %、(12 10± 0 6 6 ) %和 (15 4 5± 0 5 1) % ,组间差异显著 (P <0 0 1)。相应DEX组坏死比率分别为 (4 5 8±0 5 1) %、(4 6 6± 0 6 7) %、(2 5 36± 1 6 4 ) %和 (46 99± 2 6 7) % ,对照组分别为 (4 38± 0 39) %、(4 19± 0 73) %、(9 6 3± 1 2 5 ) %和 (13 38± 0 72 ) % ,组间差异显著 (P <0 0 1) ;电镜观察结果显示DEX处理 6h见较多典型凋亡细胞。对照组在 0min即可检测到c -Myc的明显表达 ,30min略见增多 ,1h?

AIM: To study c-Myc expression and its relationship with caspase-3 in a dexamethasone (DEX)- induced mouse thymocyte apoptosis model, and discuss the role of c-Myc in cell apoptosis. METHODS: Mouse thymocyte apoptosis was induced by 1 μmol/L DEX, the apoptotic and necrosis cells were measured by Annexin V-FITC/PI double staining flowcytometry at 30 min, 3 h, 6 h and 9 h . Electron microscopy observation was carried out at 6 h, and c-Myc and caspase-3 contents were tested by Western blot at 0, 30, 60, 180 min. RESULTS: By 1μmol/L DEX treatment, the apoptosis rates of thymocytes at 30 min, 3 h, 6 h, 9 h were (5.70±0.46)%, (35.79±1.13)%, (50.61±2.15)% and (35.52±1.66)%,respectively; in control group, they were (5.97±0.25)%, (10.20±0.71)%, (12.10±0.66)% and (15.45±0.51)% (P<0.01). At same time intervals, the necrosis rates of thymocytes in DEX group were (4.58±0.51)%, (4.66±0.67)%, (25.36±1.64)% and (46.99±2.67)%; in control group, they were (4.38±0.39)%, (4.19±0.73)%, (9.63±1.25)% and (13.38±0.72)%. Typical apoptotic cells were observed at 6 h in DEX group by electron microscopy. Obvious expression of c-Myc was detected at 0 min in control group, then c-Myc content increased at 30 min and reduced at 1 h and 3 h, in DEX group, c-Myc expression was higher than that in control group, and got a peak expression at 30 min, then significantly reduced at 1h and 3 h. Caspase-3 increased following culture time lapse in control group, while its content was more in DEX group at 0 min, peak content was detected at 30 min, and significant reduction at 1 h and 3 h. CONCLUSION: These results implied a c-Myc mediated cell apoptosis pattern in the DEX- induced mouse thymocyte apoptosis model. c-Myc and caspase-3 signals may have feedback inhibitory regulation in this process.