Rescuable folding defective NaV1.1 (SCN1A) mutants in epilepsy: Properties, occurrence, and novel rescuing strategy with peptides targeted to the endoplasmic reticulum
Rescuable folding defective NaV1.1 (SCN1A) mutants in epilepsy: Properties, occurrence, and novel rescuing strategy with peptides targeted to the endoplasmic reticulum
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DOI：
10.1016/j.nbd.2014.12.028
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发表时间：
2015-03-01
影响因子：
6.1
通讯作者：
Mantegazza, Massimo
中科院分区：
文献类型：
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作者：
Bechi, Giulia;Rusconi, Raffaella;Mantegazza, Massimo
电压门控Na+通道Nav1.1（SCNIA）的突变是不同遗传性癫痫的重要原因，也可引起家族性偏瘫性偏头痛（FHM-III）。在以前的研究中，一些可挽救的癫痫折叠缺陷突变体位于Na（v）1.1的结构域IV已被确定，显示部分功能丧失也与最大的救援。可变拯救可能是表型变异的原因之一，拯救可能被用于治疗方法。最近，我们已经确定了一个折叠缺陷FHM-Ⅲ钠（v）1.1突变体，显示整体获得的功能时，抢救，符合差分病理机制。在这里，我们已经评估了6个Na（v）1.1致癫痫错义突变在不同抢救条件下的功能特性和细胞表面表达，包括一个新的，我们已经开发的表达选择性钠通道毒素（CsEI）针对内质网（ER）。所有突变体均显示出功能丧失和细胞表面表达降低，与拯救的可能性一致。其中四个是挽救在低温下孵育和不同的共表达蛋白质或药理学伴侣（苯妥英）的相互作用。值得注意的是，CsEl能够拯救四个突变体。因此，Na（v）1.1折叠缺陷突变体可以是相对常见的，并且诱导可挽救的折叠缺陷的突变在所有Na（v）1.1结构域中分布。重要的是，致癫痫突变体即使在抢救时也显示出整体功能丧失，与FHM-III不同。CsEl的有效性证明了ER中的相互作用足以诱导拯救，并为开发可能克服药理学伴侣的一些限制的可能治疗方法提供了概念证明。(C)2015 Elsevier Inc. All rights reserved.
Mutations of the voltage gated Na+ channel Nav1.1 (SCNIA) are important causes of different genetic epilepsies and can also cause familial hemiplegic migraine (FHM-III). In previous studies, some rescuable epileptogenic folding defective mutants located in domain IV of Na(v)1.1 have been identified, showing partial loss of function also with maximal rescue. Variable rescue may be one of the causes of phenotypic variability, and rescue might be exploited for therapeutic approaches. Recently, we have identified a folding defective FHM-III Na(v)1.1 mutant that showed overall gain of function when rescued, consistent with a differential pathomechanism. Here, we have evaluated functional properties and cell surface expression of six Na(v)1.1 epileptogenic missense mutations in different rescuing conditions, including a novel one that we have developed expressing a selective sodium channel toxin (CsEI) targeted to the endoplasmic reticulum (ER). All the mutants showed loss of function and reduced cell surface expression, consistently with possibility of rescue. Four of them were rescuable by incubation at low temperature and interactions with different co-expressed proteins or a pharmacological chaperone (phenytoin). Notably, CsEl was able to rescue four mutants. Thus, Na(v)1.1 folding defective mutants can be relatively common and mutations inducing rescuable folding defects are spread in all Na(v)1.1 domains. Importantly, epileptogenic mutants showed overall loss of function even upon rescue, differently than FHM-III ones. The effectiveness of CsEl demonstrates that interactions in the ER are sufficient for inducing rescue, and provides a proof of concept for developing possible therapeutic approaches that may overcome some limitations of pharmacological chaperones. (C) 2015 Elsevier Inc. All rights reserved.