Morón José A, Abul-Husn Noura S, Rozenfeld Raphael, Dolios Georgia, Wang Rong, Devi Lakshmi A
Department of Pharmacology and Biological Chemistry, Mount Sinai School of Medicine, New York, New York 10029, USA.
Mol Cell Proteomics. 2007 Jan;6(1):29-42. doi: 10.1074/mcp.M600184-MCP200. Epub 2006 Oct 6.
Numerous studies have shown that drugs of abuse induce changes in protein expression in the brain that are thought to play a role in synaptic plasticity. Drug-induced plasticity can be mediated by changes at the synapse and more specifically at the postsynaptic density (PSD), which receives and transduces synaptic information. To date, the majority of studies examining synaptic protein profiles have focused on identifying the synaptic proteome. Only a handful of studies have examined the changes in synaptic profile by drug administration. We applied a quantitative proteomics analysis technique with the cleavable ICAT reagent to quantitate relative changes in protein levels of the hippocampal PSD in response to morphine administration. We identified a total of 102 proteins in the mouse hippocampal PSD. The majority of these were signaling, trafficking, and cytoskeletal proteins involved in synaptic plasticity, learning, and memory. Among the proteins whose levels were found to be altered by morphine administration, clathrin levels were increased to the largest extent. Immunoblotting and electron microscopy studies showed that this increase was localized to the PSD. Morphine treatment was also found to lead to a local increase in two other components of the endocytic machinery, dynamin and AP-2, suggesting a critical involvement of the endocytic machinery in the modulatory effects of morphine. Because alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are thought to undergo clathrin-mediated endocytosis, we examined the effect of morphine administration on the association of the AMPA receptor subunit, GluR1, with clathrin. We found a substantial decrease in the levels of GluR1 associated with clathrin. Taken together, these results suggest that, by causing a redistribution of endocytic proteins at the synapse, morphine modulates synaptic plasticity at hippocampal glutamatergic synapses.
大量研究表明，滥用药物会引起大脑中蛋白质表达的变化，这些变化被认为在突触可塑性中发挥作用。药物诱导的可塑性可由突触处，更具体地说是突触后致密区（PSD）的变化介导，PSD接收并转导突触信息。迄今为止，大多数研究突触蛋白质谱的研究都集中在识别突触蛋白质组上。只有少数研究通过给药来研究突触谱的变化。我们应用了可裂解的同位素亲和标签（ICAT）试剂的定量蛋白质组学分析技术，以定量吗啡给药后海马PSD中蛋白质水平的相对变化。我们在小鼠海马PSD中总共鉴定出102种蛋白质。其中大多数是参与突触可塑性、学习和记忆的信号传导、运输和细胞骨架蛋白。在发现其水平因吗啡给药而改变的蛋白质中，网格蛋白水平升高幅度最大。免疫印迹和电子显微镜研究表明，这种增加定位于PSD。还发现吗啡治疗会导致内吞机制的另外两个成分——发动蛋白和衔接蛋白2（AP-2）局部增加，这表明内吞机制在吗啡的调节作用中起关键作用。由于α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）受体被认为会经历网格蛋白介导的内吞作用，我们研究了吗啡给药对AMPA受体亚基GluR1与网格蛋白结合的影响。我们发现与网格蛋白相关的GluR1水平大幅下降。综上所述，这些结果表明，吗啡通过引起突触处内吞蛋白的重新分布，调节海马谷氨酸能突触的突触可塑性。
