The 2 tetrodotoxin-resistant (TTXr) voltage-gated sodium channel subtypes NaV1.8 and NaV1.9 are important for peripheral pain signaling. As determinants of sensory neuron excitability, they are essential for the initial transduction of sensory stimuli, the electrogenesis of the action potential, and the release of neurotransmitters from sensory neuron terminals. NaV1.8 and NaV1.9, which are encoded by SCN10A and SCN11A, respectively, are predominantly expressed in pain-sensitive (nociceptive) neurons localized in the dorsal root ganglia (DRG) along the spinal cord and in the trigeminal ganglia. Mutations in these genes cause various pain disorders in humans. Gain-of-function missense variants in SCN10A result in small fiber neuropathy, while distinct SCN11A mutations cause, i. a., congenital insensitivity to pain, episodic pain, painful neuropathy, and cold-induced pain. To determine the impact of loss-of-function of both channels, we generated NaV1.8/NaV1.9 double knockout (DKO) mice using clustered regularly interspaced short palindromic repeats/Cas-mediated gene editing to achieve simultaneous gene disruption. Successful knockout of both channels was verified by whole-cell recordings demonstrating the absence of NaV1.8- and NaV1.9-mediated Na+ currents in NaV1.8/NaV1.9 DKO DRG neurons. Global RNA sequencing identified significant deregulation of C-LTMR marker genes as well as of pain-modulating neuropeptides in NaV1.8/NaV1.9 DKO DRG neurons, which fits to the overall only moderately impaired acute pain behavior observed in DKO mice. Besides addressing the function of both sodium channels in pain perception, we further demonstrate that the null-background is a very valuable tool for investigations on the functional properties of individual human disease-causing variants in NaV1.8 or NaV1.9 in their native physiological environment.

中文翻译：

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NaV1.8/NaV1.9 双缺失轻度影响小鼠的急性疼痛反应。


2 种河豚毒素耐药 （TTXr） 电压门控钠通道亚型 NaV1.8 和 NaV1.9 对外周疼痛信号传导很重要。作为感觉神经元兴奋性的决定因素，它们对于感觉刺激的初始转导、动作电位的电发生以及感觉神经元末梢释放神经递质至关重要。NaV1.8 和 NaV1.9 分别由 SCN10A 和 SCN11A 编码，主要在位于脊髓背根神经节 （DRG） 和三叉神经节中的疼痛敏感（伤害性）神经元中表达。这些基因的突变会导致人类的各种疼痛障碍。SCN10A 中的功能获得性错义变异导致小纤维神经病变，而不同的 SCN11A 突变会导致先天性对疼痛不敏感、阵发性疼痛、疼痛性神经病变和寒冷引起的疼痛。为了确定两个通道功能丧失的影响，我们使用成簇的规则间隔短回文重复序列/Cas介导的基因编辑生成了 NaV1.8/NaV1.9 双敲除 （DKO） 小鼠，以实现同步基因破坏。全细胞记录证明 NaV1.8/NaV1.9 DKO DRG 神经元中不存在 NaV1.8 和 NaV1.9 介导的 Na + 电流，从而验证了两个通道的成功敲除。全球 RNA 测序发现 NaV1.8/NaV1.9 DKO DRG 神经元中 C-LTMR 标志基因和疼痛调节神经肽的显着失调，这符合在 DKO 小鼠中观察到的总体上唯一的中度受损急性疼痛行为。 除了解决两个钠通道在疼痛感知中的功能外，我们还进一步证明零背景是研究 NaV1.8 或 NaV1.9 中个体人类致病变体在其天然生理环境中的功能特性的非常有价值的工具。