PDF(Pubmed)
Abstract：
Pathogenic variants in KCNB1 are associated with a neurodevelopmental disorder spectrum that includes global developmental delays, cognitive impairment, abnormal electroencephalogram (EEG) patterns, and epilepsy with variable age of onset and severity. Additionally, there are prominent behavioral disturbances, including hyperactivity, aggression, and features of autism spectrum disorder. The most frequently identified recurrent variant is KCNB1-p.R306C, a missense variant located within the S4 voltage-sensing transmembrane domain. Individuals with the R306C variant exhibit mild to severe developmental delays, behavioral disorders, and a diverse spectrum of seizures. Previous in vitro characterization of R306C described altered sensitivity and cooperativity of the voltage sensor and impaired capacity for repetitive firing of neurons. Existing Kcnb1 mouse models include dominant negative missense variants, as well as knockout and frameshifts alleles. While all models recapitulate key features of KCNB1 encephalopathy, mice with dominant negative alleles were more severely affected. In contrast to existing loss-of-function and dominant-negative variants, KCNB1-p.R306C does not affect channel expression, but rather affects voltage-sensing. Thus, modeling R306C in mice provides a novel opportunity to explore impacts of a voltage-sensing mutation in Kcnb1. Using CRISPR/Cas9 genome editing, we generated the Kcnb1R306C mouse model and characterized the molecular and phenotypic effects. Consistent with the in vitro studies, neurons from Kcnb1R306C mice showed altered excitability. Heterozygous and homozygous R306C mice exhibited hyperactivity, altered susceptibility to chemoconvulsant-induced seizures, and frequent, long runs of slow spike wave discharges on EEG, reminiscent of the slow spike and wave activity characteristic of Lennox Gastaut syndrome. This novel model of channel dysfunction in Kcnb1 provides an additional, valuable tool to study KCNB1 encephalopathies. Furthermore, this allelic series of Kcnb1 mouse models will provide a unique platform to evaluate targeted therapies.
摘要：
KCNB1的致病变异与神经发育障碍谱相关，包括全球发育迟缓，认知障碍，异常脑电图（EEG）模式，以及起病年龄和严重程度不同的癫痫。此外,有突出的行为障碍，包括多动症,侵略,和自闭症谱系障碍的特征。最常见的复发变异是KCNB1-p。R306C,位于S4电压感应跨膜结构域内的错义变体。具有R306C变体的个体表现出轻度至严重的发育迟缓，行为障碍,以及各种不同的癫痫发作。R306C的先前体外表征描述了电压传感器的灵敏度和协同性改变以及神经元重复放电的能力受损。现有的Kcnb1小鼠模型包括显性否定错义变体，以及敲除和移码等位基因。虽然所有模型都概括了KCNB1脑病的关键特征，具有显性阴性等位基因的小鼠受影响更严重。与现有的功能丧失和显性阴性变体相反，KCNB1-p.R306C不影响通道表达，而是影响电压传感。因此，在小鼠中对R306C进行建模为探索电压感应突变对Kcnb1的影响提供了新的机会。使用CRISPR/Cas9基因组编辑，我们建立了Kcnb1R306C小鼠模型，并对其分子和表型效应进行了表征。与体外研究一致，来自Kcnb1R306C小鼠的神经元显示出改变的兴奋性。杂合和纯合R306C小鼠表现出过度活跃，对化学惊厥引起的癫痫发作的易感性改变，和频繁,脑电图上长时间缓慢的尖峰波放电，让人想起LennoxGastaut综合征的缓慢尖峰和波活动特征。这种新的Kcnb1通道功能障碍模型提供了额外的，研究KCNB1脑病的有价值的工具。此外，该等位基因系列Kcnb1小鼠模型将为评估靶向治疗提供一个独特的平台.
