HIV Tat Impairs Neurogenesis through Functioning As a Notch Ligand and Activation of Notch Signaling Pathway
HIV Tat Impairs Neurogenesis through Functioning As a Notch Ligand and Activation of Notch Signaling Pathway
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DOI：
10.1523/jneurosci.1208-16.2016
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发表时间：
2016-11-02
影响因子：
5.3
通讯作者：
He, Johnny J.
中科院分区：
文献类型：
--
作者：
Fan, Yan;Gao, Xiang;He, Johnny J.
在艾滋病毒感染者的大脑中发现了成人神经发生的改变，这可能与艾滋病毒相关的神经认知缺陷有关，包括学习和记忆方面的缺陷。但其潜在的分子机制尚未完全了解。在这项研究中，我们利用强力霉素诱导的星形细胞特异性HIV-1 Tat转基因小鼠（iTat），确定Tat表达与神经发生之间的关系。星形胶质细胞中的Tat表达与小鼠大脑海马齿状回中神经元祖细胞（npc）、未成熟神经元和成熟神经元的减少有关。体外神经球实验表明，星形胶质细胞中含有Tat的条件培养基或重组Tat蛋白可抑制鼻咽癌的增殖和迁移，并改变鼻咽癌的分化，而含Tat的条件培养基中含有Tat的免疫缺失或重组Tat的热灭活可消除这些影响。Notch信号下游基因Hes1启动子驱动的荧光素酶报告基因检测和Western blotting显示，重组Tat或含Tat的条件培养基激活了Hes1的转录和蛋白表达，而这些转录和蛋白表达被Tat热失活、免疫缺失和30位半胱氨酸突变所取消。最后，Notch信号抑制剂N-[N-（3,5-二氟苯乙酰基）- l -丙氨基]- s -苯基甘氨酸t-丁基酯（DAPT）在体外和体内显著挽救了tat受损的鼻咽癌分化和神经发生。总之，这些结果表明Tat通过Notch信号对npc和神经发生产生不利影响，并指出开发Notch信号抑制剂作为HIV/神经艾滋病治疗药物的潜力。
Alterations in adult neurogenesis have been noted in the brain of HIV-infected individuals and are likely linked to HIV-associated neurocognitive deficits, including those in learning and memory. But the underlying molecular mechanisms are not fully understood. In the study, we took advantage of doxycycline-inducible and astrocyte-specific HIV-1 Tat transgenic mice (iTat) and determined the relationship between Tat expression and neurogenesis. Tat expression in astrocytes was associated with fewer neuron progenitor cells (NPCs), fewer immature neurons, and fewer mature neurons in the dentate gyrus of the hippocampus of the mouse brain. In vitro NPC-derived neurosphere assays showed that Tat-containing conditioned media from astrocytes or recombinant Tat protein inhibited NPC proliferation and migration and altered NPC differentiation, while immunodepletion of Tat from Tat-containing conditioned media or heat inactivation of recombinant Tat abrogated those effects. Notch signaling downstream gene Hes1 promoter-driven luciferase reporter gene assay and Western blotting showed that recombinant Tat or Tat-containing conditioned media activated Hes1 transcription and protein expression, which were abrogated by Tat heat inactivation, immunodepletion, and cysteine mutation at position 30. Last, Notch signaling inhibitor N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT) significantly rescued Tat-impaired NPC differentiation in vitro and neurogenesis in vivo. Together, these results show that Tat adversely affects NPCs and neurogenesis through Notch signaling and point to the potential of developing Notch signaling inhibitors as HIV/neuroAIDS therapeutics.