Autism-associated R451C mutation in neuroligin3 leads to activation of the unfolded protein response in a PC12 Tet-On inducible system.
Autism-associated R451C mutation in neuroligin3 leads to activation of the unfolded protein response in a PC12 Tet-On inducible system.
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DOI：
10.1042/bj20150274
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发表时间：
2016-02-15
期刊：
影响因子：
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通讯作者：
De Jaco A
中科院分区：
文献类型：
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作者：
Ulbrich L;Favaloro FL;Trobiani L;Marchetti V;Patel V;Pascucci T;Comoletti D;Marciniak SJ;De Jaco A
自闭症相关突变体R451C neuroigin3的表达激活了神经元样PC12细胞中未折叠蛋白反应的三个分支，并导致反应靶基因BiP和CHOP的上调。几种形式的单基因遗传性自闭症谱系障碍与神经素基因突变有关。神经木质素3中自闭症相关的替代R451C诱导其胞外结构域的局部错误折叠，导致表达细胞的内质网部分保留。我们建立了一个PC12 Tet-On细胞模型系统，诱导表达野生型或R451C神经球蛋白3，以研究错误折叠蛋白保留是否会激活UPR（未折叠蛋白反应）。作为蛋白质错误折叠的阳性对照，我们还表达了突变体G221R neurorigin3，已知其完全保留在内质网内。我们的数据显示，R451C或G221R突变蛋白的过表达会导致应激传感器ATF6（激活转录因子6）、IRE1（肌醇要求酶1）和PERK （PKR （dsrna依赖性蛋白激酶）样内质网激酶）下游UPR的所有三个信号分支的激活。每个分支显示出不同的激活谱，这与每个突变引起的错误折叠程度部分相关。我们还发现，在增殖细胞和分化为神经元样表型的细胞中，两种突变蛋白均可诱导BiP（免疫球蛋白重链结合蛋白）和CHOP [C/EBP （CCAAT/增强子结合蛋白）-同源蛋白]的上调，而野生型神经木素3则不能。总的来说，我们的数据表明，突变体R451C神经球蛋白3在一种新的细胞模型系统中激活了UPR，这表明这种细胞反应可能在以错误折叠突变为特征的单基因自闭症中起作用。
The expression of the autism-related mutant R451C neuroligin3 activates the three branches of the unfolded protein response in neuronal-like PC12 cells and leads to up-regulation of the response target genes BiP and CHOP. Several forms of monogenic heritable autism spectrum disorders are associated with mutations in the neuroligin genes. The autism-linked substitution R451C in neuroligin3 induces local misfolding of its extracellular domain, causing partial retention in the ER (endoplasmic reticulum) of expressing cells. We have generated a PC12 Tet-On cell model system with inducible expression of wild-type or R451C neuroligin3 to investigate whether there is activation of the UPR (unfolded protein response) as a result of misfolded protein retention. As a positive control for protein misfolding, we also expressed the mutant G221R neuroligin3, which is known to be completely retained within the ER. Our data show that overexpression of either R451C or G221R mutant proteins leads to the activation of all three signalling branches of the UPR downstream of the stress sensors ATF6 (activating transcription factor 6), IRE1 (inositol-requiring enzyme 1) and PERK [PKR (dsRNA-dependent protein kinase)-like endoplasmic reticulum kinase]. Each branch displayed different activation profiles that partially correlated with the degree of misfolding caused by each mutation. We also show that up-regulation of BiP (immunoglobulin heavy-chain-binding protein) and CHOP [C/EBP (CCAAT/enhancer-binding protein)-homologous protein] was induced by both mutant proteins but not by wild-type neuroligin3, both in proliferative cells and cells differentiated to a neuron-like phenotype. Collectively, our data show that mutant R451C neuroligin3 activates the UPR in a novel cell model system, suggesting that this cellular response may have a role in monogenic forms of autism characterized by misfolding mutations.