通过抑制ATM上调Bim促进小脑颗粒神经元凋亡

Inhibition of ATM Promotes Neuronal Apoptosis through Upregulating Bim Expression

【目的】研究抑制共济失调毛细血管扩张突变(ATM)蛋白对SD大鼠小脑颗粒神经元(CGN)凋亡的影响及机制。【方法】将原代培养7～8 d的CGN分为25 K组、5 K组和ATM抑制组。分别应用含有25和5 mmol/L KCl的培养基处理25 K组和5 K组,建立体外神经元存活和凋亡模型。在25 K神经元存活模型中,应用ATM抑制剂KU-55933(10μmol/L,ATM抑制组)、KU-55933联合Mithramycin A(1μmol/L,MMA组)或Chromomycin A3(0.3μmol/L,CMA3组)处理,用Western Blot方法检测p-ATM、ATM、Bim、Caspase 3的表达水平,用Hoechst染色法观察并统计核固缩情况。【结果】Western Blot结果显示,与25 K组比较,5 K组和ATM抑制组的Bim、Caspase 3蛋白表达均上调(P <0.05)。核染色结果显示,与25 K组比较,5 K组和ATM抑制组核固缩率均明显增多(P <0.05)。与ATM抑制组比较,MMA组和CMA3组中Bim表达、Caspase3活性及核固缩率均明显减少。【结论】抑制ATM上调Bim活性,促进小脑颗粒神经元凋亡。

【Objective】To investigate the mechanisms implicated in ataxia telangiectasia mutated(ATM)inhibitioncaused apoptosis in the cultured cerebellar granule neurons.【Methods】Primary cerebellar granule neurons(CGN)isolated from neonatal Sprague Dawley rats of 7-8 days were divided into the following groups:25 K group(survival group),5 K group(apoptosis group)and 25 K + KU-55933 treatment group(ATM inhibition group),25 K + KU-55933 + Mithramycin A treatment group(MMA group),25 K + KU-55933 + Chromonycin A3 treatment group(CMA3 group). The protein expression of p-ATM,ATM,Bim and Caspase 3 were detected by Western Blot. The apoptotic cells with nuclear pyknosis were detected by Hoechst-staining.【Results】Compared with 25 K group,the result of western blot showed that the protein expression of Bim and Caspase 3 were increased in the ATM inhibition group(P<0.05). Compared with 25 K group,the nuclear pyknosis rate of 5 K group and ATM inhibition group were significantly increased(P<0.05). Inhibition of Bim by Mithramycin A or Chromomycin A3 remarkably reversed ATM inhibition-caused apoptosis.【Conclusion】Inhibition of ATM induce Bim dependent apoptosis in cultured cerebellar granule neurons.