Requirement of 3-phosphoinositide-dependent protein kinase-1 for BDNF-mediated neuronal survival.
Requirement of 3-phosphoinositide-dependent protein kinase-1 for BDNF-mediated neuronal survival.
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DOI：
10.1523/jneurosci.2135-08.2008
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发表时间：
2008-10-29
期刊：
影响因子：
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通讯作者：
Hetman M
中科院分区：
文献类型：
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作者：
Kharebava G;Makonchuk D;Kalita KB;Zheng JJ;Hetman M
尽管PDK 1调节对神经营养因子应答的几种信号通路，但其参与神经营养因子介导的存活的直接证据尚未报道。在这里，我们显示高活性PDK 1在大鼠皮层和海马神经元的表达在发展阶段与细胞外生存信号的明显依赖。此外，在培养的新生大鼠皮层神经元中，BDNF导致PDK 1和细胞外信号调节激酶1/2（ERK 1/2）介导的直接靶点p90核糖体S6激酶1/2（RSK 1/2）活化。在营养剥夺的皮层神经元中，内源性PDK 1的敲低减弱了对10 ng/ml BDNF的抗凋亡存活反应，而PDK 1的过度表达的活性突变形式减少了凋亡。BDNF或活性PDK 1的神经保护作用需要RSK 1/2。相反，PDK 1敲低逆转了将过表达的RSK 1与低的亚保护性BDNF浓度（2ng/ml）组合的存活效应。同样，通过活性RSK 1突变体的共表达增强了过表达的活性PDK 1的保护作用。在BDNF刺激的神经元中，RSK 1/2的激活需要PDK 1和ERK 1/2，ERK 1/2敲除去除了BDNF介导的存活。选择性激活ERK 1/2与过表达的活性突变形式的MKK 1导致RSK 1/2和PDK 1依赖性神经保护。最后，在亚保护性质粒DNA剂量下，活性MKK 1和PDK 1突变体的过表达对存活产生协同效应。我们的研究结果表明PDK 1-RSK 1/2信号在BDNF介导的神经元存活中起关键作用。因此，PDK 1对于ERK 1/2通路的抗凋亡作用是不可或缺的，提供了先前未被认识的存活信号处理和整合层。
Although PDK1 regulates several signaling pathways that respond to neurotrophins, direct evidence for its involvement in neurotrophin-mediated survival has not yet been reported. Here we show high neuronal expression of active PDK1 in the rat cortex and hippocampus at the developmental stages with pronounced dependence on extracellular survival signals. Also, in cultured cortical neurons from newborn rats, BDNF resulted in PDK1- and extracellular signal-regulated kinase-1/2 (ERK1/2)-mediated activation of their direct target, the p90 ribosomal S6 kinase 1/2 (RSK1/2). In trophic-deprived cortical neurons, knockdown of endogenous PDK1 attenuated the anti-apoptotic survival response to 10 ng/ml BDNF, while an overexpressed active mutant form of PDK1 reduced apoptosis. The neuroprotection by BDNF or active PDK1 required RSK1/2. Conversely, PDK1 knockdown reversed the survival effects of combining the overexpressed RSK1 with a low, sub-protective BDNF concentration of 2 ng/ml. Likewise, the protection by the overexpressed, active PDK1 was enhanced by co-expression of an active RSK1 mutant. Consistent with the observations that in BDNF-stimulated neurons RSK1/2 activation required both PDK1 and ERK1/2, ERK1/2 knockdown removed BDNF-mediated survival. Selective activation of ERK1/2 with an overexpressed active mutant form of MKK1 resulted in RSK1/2- and PDK1-dependent neuroprotection. Finally, at sub-protective plasmid DNA dosage, overexpression of the active MKK1 and PDK1 mutants produced synergistic effect on survival. Our findings indicate a critical role for PDK1-RSK1/2 signaling in BDNF-mediated neuronal survival. Thus, the PDK1 is indispensable for the anti-apoptotic effects of the ERK1/2 pathway offering previously unrecognized layer of survival signal processing and integration.