Two-step activation of FOXO3 by AMPK generates a coherent feed-forward loop determining excitotoxic cell fate
Two-step activation of FOXO3 by AMPK generates a coherent feed-forward loop determining excitotoxic cell fate
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DOI：
10.1038/cdd.2012.49
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发表时间：
2012-10-01
影响因子：
12.4
通讯作者：
Prehn, J. H. M.
中科院分区：
文献类型：
--
作者：
Davila, D.;Connolly, N. M. C.;Prehn, J. H. M.
脑缺血和兴奋性毒性损伤可导致短暂或永久性的生物能量衰竭，并可导致神经元凋亡或坏死。我们以前已经表明，ATP耗竭和激活的AMP激活的蛋白激酶（AMPK）在兴奋性损伤诱导神经元凋亡的促凋亡BH 3-唯一的蛋白，Bim的转录。然而，AMPK也在神经元中发挥促存活功能。决定这些不同结果的分子开关还没有很好地理解。使用生物化学，单细胞成像和计算建模相结合的方法，我们在这里证明，兴奋性毒性损伤激活的BIM启动子的FOXO 3依赖的方式。AMPK的激活降低了AKT的激活，并导致FOXO 3的去磷酸化和核转位。随后的突变研究表明，在兴奋性毒性损伤过程中，bim基因激活需要细胞核中AMPK直接磷酸化FOXO 3作为第二个激活步骤。抑制这种磷酸化阻止Bim表达和保护神经元免受兴奋性毒性和氧/葡萄糖剥夺诱导的损伤。系统分析和计算建模表明，这两个激活步骤定义了一个连贯的前馈回路;一个网络基序，能够过滤任何短期AMPK激活对bim基因诱导的影响。这可以防止不必要的AMPK介导的Bim表达和细胞凋亡在短暂的或生理的生物能量应激。Cell Death and Differentiation（2012）19，1677-1688; doi：10.1038/cdd.2012.49; 2012年4月27日在线发表
Cerebral ischemia and excitotoxic injury induce transient or permanent bioenergetic failure, and may result in neuronal apoptosis or necrosis. We have previously shown that ATP depletion and activation of AMP-activated protein kinase (AMPK) during excitotoxic injury induces neuronal apoptosis by transcription of the pro-apoptotic BH3-only protein, Bim. AMPK, however, also exerts pro-survival functions in neurons. The molecular switches that determine these differential outcomes are not well understood. Using an approach combining biochemistry, single-cell imaging and computational modeling, we here demonstrate that excitotoxic injury activated the bim promoter in a FOXO3-dependent manner. The activation of AMPK reduced AKT activation, and led to dephosphorylation and nuclear translocation of FOXO3. Subsequent mutation studies indicated that bim gene activation during excitotoxic injury required direct FOXO3 phosphorylation by AMPK in the nucleus as a second activation step. Inhibition of this phosphorylation prevented Bim expression and protected neurons against excitotoxic and oxygen/glucose deprivation-induced injury. Systems analysis and computational modeling revealed that these two activation steps defined a coherent feed-forward loop; a network motif capable of filtering any effects of short-term AMPK activation on bim gene induction. This may prevent unwanted AMPK-mediated Bim expression and apoptosis during transient or physiological bioenergetic stress. Cell Death and Differentiation (2012) 19, 1677-1688; doi:10.1038/cdd.2012.49; published online 27 April 2012