Department of Histology and Embryology, College of Basic Medical Sciences, Dalian Medical University, Dalian 116044, China.
Molecules. 2022 Jun 29;27(13):4160. doi: 10.3390/molecules27134160.
As a neurodegenerative disease, Alzheimer's disease (AD) seriously affects the health of older people. Changes in synapses occur first over the course of the disease, perhaps even before the formation of Aβ plaques. Histone deacetylase (HDAC) mediates the damage of Aβ oligomers to dendritic spines. Therefore, we examined the relationship between HDAC activity and synaptic defects using an HDAC inhibitor (HDACI), BG45, in the human neuroblastoma SH-SY5Y cell line with stable overexpression of Swedish mutant APP (APPsw) and in APP/PS1 transgenic mice during this study. The cells were treated with 15 μM BG45 and the APP/PS1 mice were treated with 30 mg/kg BG45. We detected the levels of synapse-related proteins, HDACs, tau phosphorylation, and amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors using Western blotting and immunohistochemistry. We also measured the expression of cytoskeletal proteins in the cell model. The mRNA levels of the glutamate ion receptor alginate subunit 2 (GRIK2), sodium voltage-gated channel beta subunit (SCN3B), synaptophysin (SYP), Grm2 (the gene encoding glutamate receptor subunit 2 (GluR2)), Grid2IP, glutamate receptor interacting protein 1 (GRIP1), and GRIP2 were detected to explore the effects of the HDACI on regulating the expression of synaptic proteins and AMPA receptors. According to our studies, the expressions of HDAC1, HDAC2, and HDAC3 were increased, which were accompanied by the downregulation of the synapse-related proteins SYP, postsynaptic dendritic protein (PSD-95), and spinophilin as early as 24 h after transfection with the APPsw gene. BG45 upregulated the expression of synapse-related proteins and repaired cytoskeletal damage. In vivo, BG45 alleviated the apoptosis-mediated loss of hippocampal neurons, upregulated synapse-related proteins, reduced Aβ deposition and phosphorylation of tau, and increased the levels of the synapse-related genes GRIK2, SCN3B, SYP, Grm2, and Grid2IP. BG45 increased the expression of the AMPA receptor subunits GluA1, GluA2, and GluA3 on APPsw-transfected cells and increased GRIP1 and GRIP2 expression and AMPA receptor phosphorylation in vivo. Based on these results, HDACs are involved in the early process of synaptic defects in AD models, and BG45 may rescue synaptic damage and the loss of hippocampal neurons by specifically inhibiting HDAC1, HDAC2, and HDAC3, thereby modulating AMPA receptor transduction, increasing synapse-related gene expression, and finally enhancing the function of excitatory synapses. BG45 may be considered a potential drug for the treatment of early AD in further studies.
作为一种神经退行性疾病，阿尔茨海默病（AD）严重影响老年人的健康。在疾病发展过程中，首先会发生突触的变化，甚至可能在 Aβ 斑块形成之前就已经发生了。组蛋白去乙酰化酶（HDAC）介导 Aβ 低聚物对树突棘的损伤。因此，在本研究中，我们使用组蛋白去乙酰化酶抑制剂（HDACI）BG45 在稳定过表达瑞典突变 APP（APPsw）的人神经母细胞瘤 SH-SY5Y 细胞系和 APP/PS1 转基因小鼠中研究了 HDAC 活性与突触缺陷之间的关系。细胞用 15 μM BG45 处理，APP/PS1 小鼠用 30mg/kg BG45 处理。我们使用 Western blot 和免疫组织化学检测突触相关蛋白、HDAC、tau 磷酸化和氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）受体的水平。我们还在细胞模型中测量了细胞骨架蛋白的表达。用谷氨酸离子受体海藻糖亚基 2（GRIK2）、钠电压门控通道 β 亚基（SCN3B）、突触小体相关蛋白（SYP）、Grm2（编码谷氨酸受体亚基 2（GluR2）的基因）、Grid2IP、谷氨酸受体相互作用蛋白 1（GRIP1）和 GRIP2 的 mRNA 水平来检测 HDACI 调节突触蛋白和 AMPA 受体表达的作用。根据我们的研究，早在转染 APPsw 基因 24 小时后，HDAC1、HDAC2 和 HDAC3 的表达增加，伴随着突触相关蛋白 SYP、突触后树突蛋白（PSD-95）和棘蛋白的下调。BG45 上调了突触相关蛋白的表达并修复了细胞骨架损伤。在体内，BG45 减轻了海马神经元凋亡介导的丢失，上调了突触相关蛋白，减少了 Aβ 沉积和 tau 磷酸化，增加了突触相关基因 GRIK2、SCN3B、SYP、Grm2 和 Grid2IP 的水平。BG45 增加了 APPsw 转染细胞上 AMPA 受体亚基 GluA1、GluA2 和 GluA3 的表达，并增加了体内 GRIP1 和 GRIP2 的表达和 AMPA 受体磷酸化。基于这些结果，HDAC 参与了 AD 模型中突触缺陷的早期过程，BG45 可能通过特异性抑制 HDAC1、HDAC2 和 HDAC3 来挽救突触损伤和海马神经元的丢失，从而调节 AMPA 受体转导，增加突触相关基因的表达，最终增强兴奋性突触的功能。在进一步的研究中，BG45 可能被认为是治疗早期 AD 的潜在药物。
