A rare autism-associated MINT2/APBA2 mutation disrupts neurexin trafficking and synaptic function
A rare autism-associated MINT2/APBA2 mutation disrupts neurexin trafficking and synaptic function
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DOI：
10.1038/s41598-019-42635-7
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发表时间：
2019-04-15
影响因子：
4.6
通讯作者：
Ho, Angela
中科院分区：
文献类型：
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作者：
Lin, Amy Y.;Henry, Shawna;Ho, Angela
MINT2/APBA2是参与兴奋性突触传递的突触接头蛋白。在自闭症谱系障碍（asd）中发现了几个MINT2的非同义编码变异；然而，这些罕见的变异尚未进行功能检查，致病机制尚不清楚。在这里，我们研究了大鼠Mint2 N723S突变（相当于自闭症相关的人类Mint2 N722S突变）的突触效应，该突变靶向Mint2第二个PDZ结构域的保守天冬酰胺残基，该残基与神经素-1 α (Nrxn1 α)结合，Nrxn1 α是一种与自闭症有关的突触前细胞粘附蛋白。我们发现N723S突变破坏了Nrxn1 α的稳定性和向膜的运输，而与Nrxn1 α的结合不受影响。通过对小鼠原代神经元的延时成像，我们发现与Mint2野生型相比，N723S突变体在神经元突起处有更多的不动点。因此，我们推断N723S突变体可能改变Nrxn1 α在轴突过程到突触前末端的共转运。事实上，我们发现N723S突变影响了Nrxn1 α在突触前末端的定位，这与nrxn介导的突触发生减少和兴奋性突触的微型事件频率有关。总之，我们的数据显示Mint2 N723S导致神经元功能障碍，部分原因是Nrxn1 α表面运输和Mint2突触功能的改变。
MINT2/APBA2 is a synaptic adaptor protein involved in excitatory synaptic transmission. Several nonsynonymous coding variants in MINT2 have been identified in autism spectrum disorders (ASDs); however, these rare variants have not been examined functionally and the pathogenic mechanisms are unknown. Here, we examined the synaptic effects of rat Mint2 N723S mutation (equivalent to autism-linked human MINT2 N722S mutation) which targets a conserved asparagine residue in the second PDZ domain of Mint2 that binds to neurexin-1 alpha (Nrxn1 alpha), a presynaptic cell-adhesion protein implicated in ASDs. We show the N723S mutation impairs Nrxn1 alpha stabilization and trafficking to the membrane while binding to Nrxn1 alpha remains unaffected. Using time-lapse imaging in primary mouse neurons, we found that the N723S mutant had more immobile puncta at neuronal processes compared to Mint2 wild type. We therefore, reasoned that the N723S mutant may alter the co-transport of Nrxn1 alpha at axonal processes to presynaptic terminals. Indeed, we found the N723S mutation affected Nrxn1 alpha localization at presynaptic terminals which correlated with a decrease in Nrxn-mediated synaptogenesis and miniature event frequency in excitatory synapses. Together, our data reveal Mint2 N723S leads to neuronal dysfunction, in part due to alterations in Nrxn1 alpha surface trafficking and synaptic function of Mint2.