Generation and basic characterization of a gene-trap knockout mouse model of Scn2a with a substantial reduction of voltage-gated sodium channel Nav1.2 expression
Generation and basic characterization of a gene-trap knockout mouse model of Scn2a with a substantial reduction of voltage-gated sodium channel Nav1.2 expression
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DOI：
10.1111/gbb.12725
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发表时间：
2021-01-18
影响因子：
2.5
通讯作者：
Yang, Yang
中科院分区：
文献类型：
--
作者：
Eaton, Muriel;Zhang, Jingliang;Yang, Yang
大规模遗传学研究表明，SCN2A 是神经发育障碍患者中最常见的突变基因之一。 SCN2A 编码中枢神经系统神经元中表达的电压门控钠通道亚型 1.2 (Na(v)1.2)。小鼠中 Scn2a 纯合敲除 (null) 是围产期致死的，而 Scn2a 杂合敲除 (Scn2a(+/-)) 会导致轻度行为异常。据报道，Scn2a(+/-) 小鼠中的 Na(v)1.2 表达水平约为野生型 (WT) 水平的 50-60%，这表明 Na(v)1.2 表达减少近 50% 可能不足以导致小鼠出现主要行为表型。为了克服这一障碍，我们使用靶向基因陷阱敲除（gtKO）策略表征了严重 Scn2a 缺陷的新型小鼠模型。这种方法产生了可存活的纯合小鼠 (Scn2a(gtKO/gtKO))，它们可以存活到成年，与 WT 小鼠相比，Na(v)1.2 表达量约为 1/4。 Scn2a(gtKO/gtKO) 小鼠的筑巢和交配等先天行为受到严重破坏。值得注意的是，在旷场测试中，与 WT 相比，Scn2a(gtKO/gtKO) 小鼠的中心持续时间显着缩短，这表明在新的开放空间中存在类似焦虑的行为。这些小鼠的耐热性和耐冷性也降低。此外，Scn2a(gtKO/gtKO) 小鼠在新物体探索测试中增加了固定模式探索，并且梳理行为略有增加，表明可检测到重复行为水平。他们很少甚至不埋弹珠，并且与新奇物体的互动也减少了。因此，这些 Scn2a 基因陷阱敲除小鼠提供了一个独特的模型来研究与严重 Scn2a 缺陷相关的病理生理学。
Large-scale genetic studies revealed SCN2A as one of the most frequently mutated genes in patients with neurodevelopmental disorders. SCN2A encodes for the voltage-gated sodium channel isoform 1.2 (Na(v)1.2) expressed in the neurons of the central nervous system. Homozygous knockout (null) of Scn2a in mice is perinatal lethal, whereas heterozygous knockout of Scn2a (Scn2a(+/-)) results in mild behavior abnormalities. The Na(v)1.2 expression level in Scn2a(+/-) mice is reported to be around 50-60% of the wild-type (WT) level, which indicates that a close to 50% reduction of Na(v)1.2 expression may not be sufficient to lead to major behavioral phenotypes in mice. To overcome this barrier, we characterized a novel mouse model of severe Scn2a deficiency using a targeted gene-trap knockout (gtKO) strategy. This approach produces viable homozygous mice (Scn2a(gtKO/gtKO)) that can survive to adulthood, with about a quarter of Na(v)1.2 expression compared to WT mice. Innate behaviors like nesting and mating were profoundly disrupted in Scn2a(gtKO/gtKO) mice. Notably, Scn2a(gtKO/gtKO) mice have a significantly decreased center duration compared to WT in the open field test, suggesting anxiety-like behaviors in a novel, open space. These mice also have decreased thermal and cold tolerance. Additionally, Scn2a(gtKO/gtKO) mice have increased fix-pattern exploration in the novel object exploration test and a slight increase in grooming, indicating a detectable level of repetitive behaviors. They bury little to no marbles and have decreased interaction with novel objects. These Scn2a gene-trap knockout mice thus provide a unique model to study pathophysiology associated with severe Scn2a deficiency.