PDF(Pubmed)
Abstract：
The voltage-gated potassium ion channel KV11.1 plays a critical role in cardiac repolarization. Genetic variants that render Kv11.1 dysfunctional cause long QT syndrome (LQTS), which is associated with fatal arrhythmias. Approximately 90% of LQTS-associated variants cause intracellular protein transport (trafficking) dysfunction, which pharmacological chaperones like E-4031 can rescue. Protein folding and trafficking decisions are regulated by chaperones, protein quality control factors, and trafficking machinery comprising the cellular proteostasis network. Here, we test whether trafficking dysfunction is associated with alterations in the proteostasis network of pathogenic Kv11.1 variants and whether pharmacological chaperones can normalize the proteostasis network of responsive variants. We used affinity-purification coupled with tandem mass tag-based quantitative mass spectrometry to assess protein interaction changes of WT KV11.1 or trafficking-deficient channel variants in the presence or absence of E-4031. We identified 572 core KV11.1 protein interactors. Trafficking-deficient variants KV11.1-G601S and KV11.1-G601S-G965∗ had significantly increased interactions with proteins responsible for folding, trafficking, and degradation compared to WT. We confirmed previous findings that the proteasome is critical for KV11.1 degradation. Our report provides the first comprehensive characterization of protein quality control mechanisms of KV11.1. We find extensive interactome remodeling associated with trafficking-deficient KV11.1 variants and with pharmacological chaperone rescue of KV11.1 cell surface expression. The identified protein interactions could be targeted therapeutically to improve KV11.1 trafficking and treat LQTS.
摘要：
电压门控钾离子通道KV11.1在心脏复极化中起关键作用。导致Kv11.1功能失调的遗传变异导致长QT综合征（LQTS），这与致命的心律失常有关。大约90％的LQTS相关变体导致细胞内蛋白质转运（运输）功能障碍，像E-4031这样的药物伴侣可以拯救。蛋白质折叠和贩运决定受伴侣调节，蛋白质质量控制因素，和包含细胞蛋白质停滞网络的贩运机器。这里,我们测试了贩运功能障碍是否与致病性Kv11.1变异体的蛋白稳定网络的改变相关,以及药理学伴侣是否可以使应答性变异体的蛋白稳定网络正常化.我们使用亲和纯化结合基于串联质量标签的定量质谱来评估在存在或不存在E4031的情况下野生型(WT)KV11.1或运输缺陷型通道变体的蛋白质相互作用变化。我们鉴定了572个核心KV11.1蛋白相互作用物。贩运缺陷型变体KV11.1-G601S和KV11.1-G601S-G965*与负责折叠的蛋白质的相互作用显着增加，贩运，与WT相比退化。我们证实了先前的发现，蛋白酶体对于KV11.1降解至关重要。我们的报告首次全面描述了KV11.1的蛋白质质量控制机制。我们发现与贩运缺陷型KV11.1变体相关的广泛的相互作用组重塑，并与药理伴侣解救KV11.1细胞表面表达。鉴定的蛋白质相互作用可以在治疗上靶向改善KV11.1运输和治疗长QT综合征。
