BK channel properties correlate with neurobehavioral severity in three KCNMA1-linked channelopathy mouse models.
BK channel properties correlate with neurobehavioral severity in three KCNMA1-linked channelopathy mouse models.
复制标题
BK通道特性与三种KCNMA1连锁通道病小鼠模型的神经行为严重程度相关。
DOI：
10.7554/elife.77953
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发表时间：
2022-07-12
期刊：
影响因子：
7.7
通讯作者：
Meredith, Andrea
中科院分区：
文献类型：
--
作者：
Park, Su Mi;Roache, Cooper E.;Iffland II, Philip H.;Moldenhauer, Hans J.;Matychak, Katia K.;Plante, Amber E.;Lieberman, Abby G.;Crino, Peter B.;Meredith, Andrea
关键词：
KCNMA 1形成BK K+通道的孔，其调节神经元和肌肉兴奋性。最近，基因筛查在一个衰弱性阵发性非运动诱发性运动障碍患者亚组中发现了杂合KCNMA 1变体，这些患者表现为癫痫或非癫痫（PNKD 3）。然而，KCNMA 1突变的相关性和PNKD 3临床异质性的基础尚未建立。在这里，我们评估了BK通道，神经元和小鼠中三种KCNMA 1患者变体的相对严重程度。在异源细胞中，BKN 999 S和BKD 434 G通道显示出功能获得（GOF）特性，而BKH 444 Q通道显示出功能丧失（LOF）特性。通道活性的相对强弱为BKN 999 S> BKD 434 G>WT > BKH 444 Q。在Kcnma 1 N999 S/WT和Kcnma 1D 434 G/WT转基因小鼠中，BK电流和动作电位放电增加，癫痫发作阈值降低，但在Kcnma 1H 444 Q/WT小鼠中没有。在一项针对阵发性运动障碍的新行为测试中，受影响更严重的Kcnma 1 N999 S/WT小鼠在应激后变得不动。这是废除了急性苯丙胺治疗，与PNKD 3受影响的个人。纯合子Kcnma 1D 434 G/D434 G小鼠表现出类似的不动性，但相比之下，纯合子Kcnma 1H 444 Q/H444 Q小鼠表现出多动行为。这些数据确立了患者等位基因的相对致病潜力为N999 S> D434 G> H444 Q，并验证了Kcnma 1 N999 S/WT小鼠作为具有增加的癫痫发作倾向的PNKD 3模型。到目前为止，全世界只有70名患者被诊断出患有一种新发现的罕见综合征，称为KCNMA 1相关通道病。这种情况的特点是癫痫发作和异常运动，包括频繁的“跌倒攻击”，肌肉控制的突然和衰弱的损失，导致患者在没有警告的情况下摔倒。这种疾病与KCNMA 1基因突变有关，KCNMA 1是一类对控制神经细胞活动和大脑功能很重要的蛋白质。然而，由于受这种疾病影响的人数有限，很难将特定的突变与观察到的症状联系起来;因此，下落攻击的基础仍然未知。Park等人开始在实验室中建立KCNMA 1相关通道病的“模型”，以确定KCNMA 1基因中的哪些突变导致了这些症状。三组小鼠都经过基因工程改造，携带KCNMA 1基因中两种最常见的突变之一，或者一种与运动症状相关的非常罕见的突变。行为实验和神经细胞活性的研究表明，携带使KCNMA 1蛋白更活跃的突变的小鼠更容易发生癫痫发作并变得固定，显示出小鼠版本的跌落攻击。给这些老鼠服用对某些人类患者有效的药物苯丙胺，完全停止了瘫痪攻击。这些结果首次显示了哪些特定的遗传变化导致KCNMA 1连锁通道病的主要症状。Park等人希望这些知识将加深我们对这种疾病的理解，并有助于开发更好的治疗方法。
KCNMA1 forms the pore of BK K+ channels, which regulate neuronal and muscle excitability. Recently, genetic screening identified heterozygous KCNMA1 variants in a subset of patients with debilitating paroxysmal non-kinesigenic dyskinesia, presenting with or without epilepsy (PNKD3). However, the relevance of KCNMA1 mutations and the basis for clinical heterogeneity in PNKD3 has not been established. Here, we evaluate the relative severity of three KCNMA1 patient variants in BK channels, neurons, and mice. In heterologous cells, BKN999S and BKD434G channels displayed gain-of-function (GOF) properties, whereas BKH444Q channels showed loss-of-function (LOF) properties. The relative degree of channel activity was BKN999S > BKD434G>WT > BKH444Q. BK currents and action potential firing were increased, and seizure thresholds decreased, in Kcnma1N999S/WT and Kcnma1D434G/WT transgenic mice but not Kcnma1H444Q/WT mice. In a novel behavioral test for paroxysmal dyskinesia, the more severely affected Kcnma1N999S/WT mice became immobile after stress. This was abrogated by acute dextroamphetamine treatment, consistent with PNKD3-affected individuals. Homozygous Kcnma1D434G/D434G mice showed similar immobility, but in contrast, homozygous Kcnma1H444Q/H444Q mice displayed hyperkinetic behavior. These data establish the relative pathogenic potential of patient alleles as N999S>D434G>H444Q and validate Kcnma1N999S/WT mice as a model for PNKD3 with increased seizure propensity. So far, only 70 patients around the world have been diagnosed with a newly identified rare syndrome known as KCNMA1-linked channelopathy. The condition is characterised by seizures and abnormal movements which include frequent ‘drop attacks’, a sudden and debilitating loss of muscle control that causes patients to fall without warning. The disease is associated with mutations in the gene for KCNMA1, a member of a class of proteins important for controlling nerve cell activity and brain function. However, due to the limited number of people affected by the condition, it is difficult to link a particular mutation to the observed symptoms; the basis for the drop attacks therefore remains unknown. Park et al. set out to ‘model’ KCNMA1-linked channelopathy in the laboratory, in order to determine which mutations in the KCNMA1 gene caused these symptoms. Three groups of mice were each genetically engineered to carry either one of the two most common mutations in the gene for KCNMA1, or a very rare mutation associated with the movement symptoms. Behavioural experiments and studies of nerve cell activity revealed that the mice carrying mutations that made the KCNMA1 protein more active developed seizures more easily and became immobilized, showing the mouse version of drop attacks. Giving these mice the drug dextroamphetamine, which works in some human patients, stopped the immobilizing attacks altogether. These results show for the first time which specific genetic changes cause the main symptoms of KCNMA1-linked channelopathy. Park et al. hope that this knowledge will deepen our understanding of this disease and help develop better treatments.
影响因子：
6.8
作者：
Fu X;Shah AP;Keighron J;Mou TM;Ladenheim B;Alt J;Fukudome D;Niwa M;Tamashiro KL;Tanda G;Sawa A;Cadet JL;Rais R;Baraban JM
通讯作者：
Baraban JM