The endosomal trafficking regulator LITAF controls the cardiac Nav1.5 channel via the ubiquitin ligase NEDD4-2.
The endosomal trafficking regulator LITAF controls the cardiac Nav1.5 channel via the ubiquitin ligase NEDD4-2.
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DOI：
10.1074/jbc.ra120.015216
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发表时间：
2020-12-25
期刊：
影响因子：
--
通讯作者：
Koren G
中科院分区：
文献类型：
--
作者：
Turan NN;Moshal KS;Roder K;Baggett BC;Kabakov AY;Dhakal S;Teramoto R;Chiang DY;Zhong M;Xie A;Lu Y;Dudley SC Jr;MacRae CA;Karma A;Koren G
QT间期是对心电活动的记录。先前的全基因组关联研究发现了改变LITAF（脂多糖诱导的肿瘤坏死因子-α因子）上游QT间期的遗传变异，LITAF是一种编码内体运输调节因子的蛋白质。然而，目前尚不清楚LITAF如何影响心脏兴奋。我们研究了LITAF对电压门控钠通道Nav1.5的影响，这是心脏去极化的关键。我们发现，在兔心肌细胞和稳定表达Nav1.5的HEK细胞中，过表达LITAF导致Nav1.5产生的电压门控钠电流INa密度和Nav1.5表面蛋白水平显著增加。近距离结扎实验显示内源性LITAF和Nav1.5在心肌细胞中共定位，而共免疫沉淀证实它们在HEK细胞中过表达时处于相同的复合物中。体外数据表明，LITAF与泛素连接酶NEDD4-2相互作用，NEDD4-2是Nav1.5的调节因子。LITAF过表达下调NEDD4-2在心肌细胞和HEK细胞中的表达。在HEK细胞中，LITAF增加了共表达NEDD4-2的泛素化和蛋白酶体降解，显著减弱了NEDD4-2对INa的负面作用。我们得出结论，LITAF通过促进NEDD4-2的降解来控制心脏兴奋性，这是去除表面Nav1.5所必需的。litaf基因敲除的斑马鱼的动作电位持续时间增加了15%，但没有显著性延长。使用兔心肌细胞模型的计算机模拟表明，Ca2+和Na+稳态的变化是导致动作电位持续时间缩短的原因。因此，这些计算数据证实了几个全基因组关联研究的结果，这些研究将LITAF与QT间期变异联系起来。
The QT interval is a recording of cardiac electrical activity. Previous genome-wide association studies identified genetic variants that modify the QT interval upstream of LITAF (lipopolysaccharide-induced tumor necrosis factor-α factor), a protein encoding a regulator of endosomal trafficking. However, it was not clear how LITAF might impact cardiac excitation. We investigated the effect of LITAF on the voltage-gated sodium channel Nav1.5, which is critical for cardiac depolarization. We show that overexpressed LITAF resulted in a significant increase in the density of Nav1.5-generated voltage-gated sodium current INa and Nav1.5 surface protein levels in rabbit cardiomyocytes and in HEK cells stably expressing Nav1.5. Proximity ligation assays showed co-localization of endogenous LITAF and Nav1.5 in cardiomyocytes, whereas co-immunoprecipitations confirmed they are in the same complex when overexpressed in HEK cells. In vitro data suggest that LITAF interacts with the ubiquitin ligase NEDD4-2, a regulator of Nav1.5. LITAF overexpression down-regulated NEDD4-2 in cardiomyocytes and HEK cells. In HEK cells, LITAF increased ubiquitination and proteasomal degradation of co-expressed NEDD4-2 and significantly blunted the negative effect of NEDD4-2 on INa. We conclude that LITAF controls cardiac excitability by promoting degradation of NEDD4-2, which is essential for removal of surface Nav1.5. LITAF-knockout zebrafish showed increased variation in and a nonsignificant 15% prolongation of action potential duration. Computer simulations using a rabbit-cardiomyocyte model demonstrated that changes in Ca2+ and Na+ homeostasis are responsible for the surprisingly modest action potential duration shortening. These computational data thus corroborate findings from several genome-wide association studies that associated LITAF with QT interval variation.
影响因子：
3.7
作者：
Dun W;Lowe JS;Wright P;Hund TJ;Mohler PJ;Boyden PA
通讯作者：
Boyden PA