全基因组关联研究(GWAS)报道了RING指E3泛素蛋白连接酶rififylin(RFFL)的单核苷酸多态性与人类QT间期变异性之间的相关性(Newton-Cheh等。,2009).以前,我们已经表明,RFFL下调成年兔心室心肌细胞(ARbCM)中的人样ether-a-go-go相关基因(hERG)钾通道和相应的快速激活延迟整流钾电流(IKr)的表达和功能.在这里,我们报告RFFL也影响瞬态外向电流(Ito),但以一种奇特的方式。ARbCM中的RFFL过表达显着降低了其快速成分的贡献(Ito,f)从35%到21%,并增加其慢成分的贡献(伊藤,s)从65%到79%。自从伊藤,在兔中主要通过Kv4.3进行,我们研究了RFFL对HEK293A细胞中表达的Kv4.3的影响。我们发现RFFL过表达降低了Kv4.3的表达和相应的Ito,f在存在或不存在其辅助亚基KChIP2的情况下以RING结构域依赖性方式。另一方面,在表达Kv1.4的HEK细胞中RFFL过表达导致Kv1.4表达水平和Ito,s,类似地,以依赖于RING域的方式。我们的生理详细的兔心室肌细胞计算模型表明,RFFL过表达对Ito的阴阳效应,f,还有伊藤,s影响动作电位波形的1相,并且除了抑制IKr外还略微减少其持续时间。因此,RFFL通过不同地影响各种钾通道和心脏动作电位持续时间(APD)的多种蛋白质的泛素化来修饰心脏复极化储备。
Genome-wide association studies have reported a correlation between a SNP of the RING finger E3 ubiquitin protein ligase rififylin (RFFL) and QT interval variability in humans (Newton-Cheh et al., 2009). Previously, we have shown that RFFL downregulates expression and function of the human-like ether-a-go-go-related gene potassium channel and corresponding rapidly activating delayed rectifier potassium current (IKr) in adult rabbit ventricular cardiomyocytes. Here, we report that RFFL also affects the transient outward current (Ito), but in a peculiar way. RFFL overexpression in adult rabbit ventricular cardiomyocytes significantly decreases the contribution of its fast component (Ito,f) from 35% to 21% and increases the contribution of its slow component (Ito,s) from 65% to 79%. Since Ito,f in rabbits is mainly conducted by Kv4.3, we investigated the effect of RFFL on Kv4.3 expressed in HEK293A cells. We found that RFFL overexpression reduced Kv4.3 expression and corresponding Ito,f in a RING domain-dependent manner in the presence or absence of its accessory subunit Kv channel-interacting protein 2. On the other hand, RFFL overexpression in Kv1.4-expressing HEK cells leads to an increase in both Kv1.4 expression level and Ito,s, similarly in a RING domain-dependent manner. Our physiologically detailed rabbit ventricular myocyte computational model shows that these yin and yang effects of RFFL overexpression on Ito,f, and Ito,s affect phase 1 of the action potential waveform and slightly decrease its duration in addition to suppressing IKr. Thus, RFFL modifies cardiac repolarization reserve via ubiquitination of multiple proteins that differently affect various potassium channels and cardiac action potential duration.