Human Immunodeficiency Virus-1 Tat Protein Increases the Number of Inhibitory Synapses between Hippocampal Neurons in Culture
Human Immunodeficiency Virus-1 Tat Protein Increases the Number of Inhibitory Synapses between Hippocampal Neurons in Culture
复制标题
DOI：
10.1523/jneurosci.1312-13.2013
复制
发表时间：
2013-11-06
影响因子：
5.3
通讯作者：
Thayer, Stanley A.
中科院分区：
文献类型：
--
作者：
Hargus, Nicholas J.;Thayer, Stanley A.
突触树突损伤与许多神经退行性疾病中的认知下降相关，包括人类免疫缺陷病毒-1（HIV-1）相关的神经认知障碍（HAND）。由于HIV-1不感染神经元，病毒介导的毒性是间接的，由释放的神经毒素如HIV-1蛋白质转录反式激活因子（达特）引起。我们比较了达特对大鼠海马神经元之间抑制性和兴奋性突触连接的影响，使用基于成像的测定，定量簇的支架蛋白桥蛋白或PSD 95融合到GFP。达特（24 h）增加GFP-桥蛋白斑点的数量，减少PSD 95-GFP斑点的数量。达特对抑制性和兴奋性突触数目的影响是通过低密度脂蛋白受体相关蛋白和随后的含谷氨酸N 2 A的NMDA受体（NMDARs）的Ca 2+内流介导的。达特对突触数量的影响需要细胞自主激活Ca 2 + /钙调素依赖性蛋白激酶II（CaMK II）。Ca 2+缓冲实验表明，兴奋性突触的损失需要激活的CaMKII在紧密贴壁的NMDAR，而抑制性突触的增加需要Ca 2+扩散到更远的网站。抑制性突触的增加通过抑制GABA（A）受体插入细胞膜来阻止。达特（16小时）诱导的突触变化被逆转阻断含GluN 2B的NMDAR或神经元型一氧化氮合酶，表明在神经毒性过程中NMDAR亚型激活的途径的作用发生变化。抑制性和兴奋性突触数量的补偿性变化可能作为一种新的机制，以减少网络的兴奋性，在HIV-1神经毒素的存在下，这些变化可能会通知治疗手的发展。
Synaptodendritic damage correlates with cognitive decline in many neurodegenerative diseases, including human immunodeficiency virus-1 (HIV-1)-associated neurocognitive disorders (HAND). Because HIV-1 does not infect neurons, viral-mediated toxicity is indirect, resulting from released neurotoxins such as the HIV-1 protein transactivator of transcription (Tat). We compared the effects of Tat on inhibitory and excitatory synaptic connections between rat hippocampal neurons using an imaging-based assay that quantified clusters of the scaffolding proteins gephyrin or PSD95 fused to GFP. Tat (24 h) increased the number of GFP-gephyrin puncta and decreased the number of PSD95-GFP puncta. The effects of Tat on inhibitory and excitatory synapse number were mediated via the low-density lipoprotein receptor-related protein and subsequent Ca2+ influx through GluN2A-containing NMDA receptors (NMDARs). The effects of Tat on synapse number required cell-autonomous activation of Ca2+ /calmodulin-dependent protein kinase II (CaMKII). Ca2+ buffering experiments suggested that loss of excitatory synapses required activation of CaMKII in close apposition to the NMDAR, whereas the increase in inhibitory synapses required Ca2+ diffusion to a more distal site. The increase in inhibitory synapses was prevented by inhibiting the insertion of GABA(A) receptors into the membrane. Synaptic changes induced by Tat (16 h) were reversed by blocking either GluN2B-containing NMDARs or neuronal nitric oxide synthase, indicating changing roles for pathways activated by NMDAR subtypes during the neurotoxic process. Compensatory changes in the number of inhibitory and excitatory synapses may serve as a novel mechanism to reduce network excitability in the presence of HIV-1 neurotoxins; these changes may inform the development of treatments for HAND.