Interaction of Postsynaptic Density Protein-95 with NMDA Receptors Influences Excitotoxicity in the Yeast Artificial Chromosome Mouse Model of Huntington's Disease
Interaction of Postsynaptic Density Protein-95 with NMDA Receptors Influences Excitotoxicity in the Yeast Artificial Chromosome Mouse Model of Huntington's Disease
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DOI：
10.1523/jneurosci.2491-09.2009
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发表时间：
2009-09-02
影响因子：
5.3
通讯作者：
Raymond, Lynn A.
中科院分区：
文献类型：
--
作者：
Fan, Jing;Cowan, Catherine M.;Raymond, Lynn A.
有证据表明NMDA型谷氨酸受体参与了亨廷顿病(HD)纹状体中型棘神经元(MSN)的变性。此前，我们在酵母人工染色体(YAC)转基因小鼠模型中证明了NMDAR(NMDAR)介导的电流和/或毒性增加。该转基因小鼠模型表达多聚谷氨酰胺(PolyQ)-扩展(突变)全长人亨廷顿蛋白(HTT)。其他研究表明，膜相关鸟苷晚期蛋白(MAGUK)，如PSD-95和SAP102，调节NMDAR表面表达和海马神经元和皮质神经元的兴奋毒性，HTT与PSD-95相互作用。在这里，我们测试了一种假设，即突变的Huntingtin表达细胞中MAGUKs和NMDARs之间的关联改变有助于增加对兴奋性毒性的敏感性。我们发现在野生型和YAC转基因小鼠的HEK293T细胞和纹状体组织中，HTT与SAP102共沉淀；然而，SAP102与HTT或NMDAR NR2B亚单位的关联不受HTT多Q长度的影响，而PSD-95与纹状体组织中NR2B的关联随着HTT多Q长度的增加而增强。用TAT-NR2B9c多肽处理培养的MSN可阻断NR2B与SAP102和PSD-95的结合，并使YAC转基因和野生型MSN的NMDAR表面表达减少20%，并将YAC HD MSN对NMDAR兴奋毒性的敏感性恢复到野生型MSN的水平；用小干扰RNA敲除PSD-95后，观察到类似的兴奋毒性效应。与先前在大脑皮层和海马神经元中的发现不同，TAT-NR2B9c拯救NMDA毒性独立于对神经元型一氧化氮合酶活性的任何影响。我们的结果进一步阐明了HD兴奋毒性增强的机制。
Evidence suggests that NMDA-type glutamate receptors contribute to degeneration of striatal medium-sized spiny neurons (MSNs) in Huntington's disease (HD). Previously, we demonstrated that NMDA receptor (NMDAR)-mediated current and/or toxicity is increased in MSNs from the yeast artificial chromosome (YAC) transgenic mouse model expressing polyglutamine (polyQ)-expanded (mutant) full-length human huntingtin (htt). Others have shown that membrane-associated guanylate kinases (MAGUKs), such as PSD-95 and SAP102, modulate NMDAR surface expression and excitotoxicity in hippocampal and cortical neurons and that htt interacts with PSD-95. Here, we tested the hypothesis that an altered association between MAGUKs and NMDARs in mutant huntingtin-expressing cells contributes to increased susceptibility to excitotoxicity. We show that htt coimmunoprecipitated with SAP102 in HEK293T cells and striatal tissue from wild-type and YAC transgenic mice; however, the association of SAP102 with htt or the NMDAR NR2B subunit was unaffected by htt polyQ length, whereas association of PSD-95 with NR2B in striatal tissue was enhanced by increased htt polyQ length. Treatment of cultured MSNs with Tat-NR2B9c peptide blocked binding of NR2B with SAP102 and PSD-95 and reduced NMDAR surface expression by 20% in both YAC transgenic and wild-type MSNs, and also restored susceptibility to NMDAR excitoxicity in YAC HD MSNs to levels observed in wild-type MSNs; a similar effect on excitotoxicity was observed after knockdown of PSD-95 by small interfering RNA. Unlike previous findings in cortical and hippocampal neurons, rescue of NMDA toxicity by Tat-NR2B9c occurred independently of any effect on neuronal nitric oxide synthase activity. Our results elucidate further the mechanisms underlying enhanced excitotoxicity in HD.