Pharmacological and Genetic Accumulation of Hypoxia-Inducible Factor-1α Enhances Excitatory Synaptic Transmission in Hippocampal Neurons through the Production of Vascular Endothelial Growth Factor
Pharmacological and Genetic Accumulation of Hypoxia-Inducible Factor-1α Enhances Excitatory Synaptic Transmission in Hippocampal Neurons through the Production of Vascular Endothelial Growth Factor
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DOI：
10.1523/jneurosci.5493-09.2010
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发表时间：
2010-04-28
影响因子：
5.3
通讯作者：
Hsu, Kuei-Sen
中科院分区：
文献类型：
--
作者：
Huang, Yu-Fei;Yang, Chih-Hao;Hsu, Kuei-Sen
缺氧诱导因子-1（Hypoxia-inducible factor-1，HIF-1）是哺乳动物细胞中一种重要的转录因子，参与协调细胞对缺氧的适应性反应。它由调节亚基HIF-1 α和组成型表达的亚基HIF-1 β组成，调节亚基HIF-1 α在缺氧条件下积累。除了充分表征的氧依赖性HIF-1的作用模式之外，最近的研究表明，各种生长因子和细胞因子刺激HIF-1 α表达，从而通过氧非依赖性机制触发许多缺氧诱导基因的转录。在这项研究中，我们研究了胰岛素样生长因子-1（IGF-1）诱导的HIF-1 α的积累是否在海马神经元培养的兴奋性突触传递中具有调节作用。我们的研究结果表明，IGF-1诱导HIF-1 α表达的时间和剂量依赖性增加，通过选择性IGF-1受体拮抗剂，转录抑制剂和翻译抑制剂预处理阻断。此外，药物阻断磷脂酰肌醇3-激酶/Akt/哺乳动物靶向雷帕霉素信号通路，而不是细胞外信号调节激酶，抑制IGF-1诱导的HIF-1 α表达。更重要的是，IGF-1诱导的HIF-1 α表达的增加伴随着血管内皮生长因子（VEGF）mRNA和蛋白水平的增加，这增强了兴奋性突触传递。与此同时，通过棘霉素或慢病毒感染显性阴性突变HIF-1 α或靶向HIF-1 α的短发夹RNA阻断HIF-1 α活性抑制了VEGF表达的增加和IGF-1诱导的突触传递的增强。相反，将组成型活性HIF-1 α转染到神经元中模拟了IGF-1治疗的效果。总之，这些结果表明，HIF-1 α积累可以通过调节VEGF的产生来增强海马神经元中的兴奋性突触传递。
Hypoxia-inducible factor-1 (HIF-1) is an important transcriptional factor in mammalian cells for coordination of adaptive responses to hypoxia. It consists of a regulatory subunit HIF-1 alpha, which accumulates under hypoxic conditions, and a constitutively expressed subunit HIF-1 beta. In addition to the well characterized oxygen-dependent mode of action of HIF-1, recent work has shown that various growth factors and cytokines stimulate HIF-1 alpha expression, thereby triggering transcription of numerous hypoxia-inducible genes by oxygen-independent mechanisms. In this study, we examined whether accumulation of HIF-1 alpha induced by insulin-like growth factor-1 (IGF-1) has a regulatory role in excitatory synaptic transmission in hippocampal neuron cultures. Our results show that IGF-1 induced a time-and dose-dependent increase in HIF-1 alpha expression that was blocked by pretreatment with selective IGF-1 receptor antagonist, transcriptional inhibitor, and translational inhibitors. In addition, pharmacological blockade of the phosphatidylinositol 3-kinase/Akt/mammalian target of the rapamycin signaling pathway, but not extracellular signal-regulated kinase, inhibited IGF-1-induced HIF-1 alpha expression. More importantly, the increase in HIF-1 alpha expression induced by IGF-1 was accompanied by increasing levels of vascular endothelial growth factor (VEGF) mRNA and protein, which enhanced excitatory synaptic transmission. In parallel, blockade of HIF-1 alpha activity by echinomycin or lentiviral infection with dominant-negative mutant HIF-1 alpha or short hairpin RNA targeting HIF-1 alpha inhibited the increase in expression of VEGF and the enhancement of synaptic transmission induced by IGF-1. Conversely, transfection of constitutively active HIF-1 alpha into neurons mimicked the effects of IGF-1 treatment. Together, these results suggest that HIF-1 alpha accumulation can enhance excitatory synaptic transmission in hippocampal neurons by regulating production of VEGF.