A new ATP1A1 variant associated with a novel disease phenotype
A new ATP1A1 variant associated with a novel disease phenotype
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与新疾病表型相关的新 ATP1A1 变体
DOI：
10.1016/j.bpj.2023.11.2438
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发表时间：
2024
影响因子：
3.4
通讯作者：
Artigas, Pablo
中科院分区：
文献类型：
--
作者：
Conger, Lauren P.;Weigl, Yuval;Spontarelli, Kerri;Abe, Kazuhiro;Reish, Orit;Artigas, Pablo
ATP 1A 1的病理变体编码Na+，K+-ATP酶（NKA）-α1亚基（αβ异源二聚体），已知可引起醛固酮增多症、腓骨肌萎缩性侧索硬化神经病、低镁血症伴癫痫发作和认知延迟，以及一组以癫痫发作和发育延迟为特征的表型。我们在一名患有甲状腺功能减退症、先天性心脏病、阻塞性脑积水、传导性听力损失、上运动神经元症状、自闭症和全面发育迟缓的患者中发现了ATP 1A 1变体（“变体X”）。NKA水解1ATP分子，将3 Na+输出细胞，同时输入2K+，建立电化学梯度，为大多数细胞的兴奋性和次级主动运输提供动力。先前的研究已经报道了NKA-α1变体的功能特征，这可能有助于其特定的表型，总是显示NKA功能的丧失，并且在某些情况下，异常的离子通道样功能特征。为了确定在患者中观察到的新表型的合理机制，我们在非洲爪蟾卵母细胞以及HEK 293细胞中表达了突变型和人野生型以及突变型NKA-α1和β1，用于蛋白纯化后的ATP酶测定和结构分析。与野生型相比，变体X导致NKA功能丧失，如通过双电极电压钳（TEVC，n≥ 11）中K+诱导的NKA电流降低约90%和纯化蛋白中最大ATP酶活性降低所指示的。尽管富含质膜的制剂（n= 2）的蛋白质印迹中的蛋白质水平相似，但哇巴因敏感的部分反应（在不存在外部K+的情况下由电压脉冲引起的电荷移动）显示移动的总电荷减少约90%（n≥ 8），表明质膜上功能性泵的数量减少。为了评估变体X-NKA定位，在HEK 293细胞中表达功能性CFP和YFP标记的α1用于荧光显微镜检查。变体X似乎定位于质膜附近的囊泡中。正在评估合理的功能或贩运显性负效应。NSF-MCB 2003251。
Pathological variants of ATP1A1, coding for the Na+, K+-ATPase (NKA)-α1 subunit (an αβheterodimer), are known to cause hyperaldosteronism, Charcot-Marie-Tooth neuropathies, hypomagnesemia with seizures and cognitive delay, as well as a group of phenotypes characterized by seizures and developmental delay. We found an ATP1A1 variant (“variant X”) in a patient with hypothyroidism, congenital heart defects, obstructive hydrocephaly, conductive hearing loss, upper motor neuron symptoms, autism, and global developmental delay. NKA hydrolyzes 1ATP molecule to export 3Na+ out of the cell while importing 2K+, establishing electrochemical gradients that power excitability and secondary active transport in most cells. Previous studies have reported functional characteristics of the NKA-α1 variants that may contribute to their particular phenotypes, invariably showing loss of NKA function and, in some cases, aberrant ion-channel-like functional characteristics. To identify plausible mechanisms for the novel phenotypes observed in the patient, we expressed mutant and human wild type and mutant NKA-α1 with β1 in Xenopus oocytes, as well as in HEK293 cells for ATPase assays and structural analysis following protein purification. Compared to wild type, Variant X causes loss of NKA function, as indicated by a∼ 90% reduced K+-induced NKA current in two-electrode voltage clamp (TEVC, n≥ 11) and reduced maximal ATPase activity in purified protein. Despite similar protein levels in western blots from plasmalemma enriched preparations (n= 2), the ouabain-sensitive partial reactions (charge movement elicited by voltage pulses in the absence of external K+ show a∼ 90% reduction of the total charge moved (n≥ 8), indicating reduced numbers of functional pumps at the plasmalemma. To evaluate variant X-NKA localization, functional CFP-and YFP-tagged α1 were expressed in HEK293 cells for fluorescent microscopy. Variant X appears to localize in vesicles near the plasma membrane. Evaluation of plausible functional or trafficking dominant-negative effects is underway. NSF-MCB 2003251.