Department of Neurology, University of Illinois College of Medicine, Chicago, IL 60612, United States.
Department of Neurology, University of Illinois College of Medicine, Chicago, IL 60612, United States; Program in Neuroscience, University of Illinois College of Medicine, Chicago, IL 60612, United States; Jesse Brown Veterans Affairs Medical Center, Chicago, IL 60612, United States.
Immunobiology. 2019 Jan;224(1):80-93. doi: 10.1016/j.imbio.2018.10.005. Epub 2018 Oct 24.
Prior work demonstrated that a splice variant of SCN5A, a voltage-gated sodium channel gene, acts as a cytoplasmic sensor for viral dsRNA in human macrophages. Expression of this channel also polarizes macrophages to an anti-inflammatory phenotype in vitro and in vivo. Here we utilized global expression analysis of splice variants to identify novel channel-dependent signaling mechanisms. Pharmacological activation of voltage-gated sodium channels in human macrophages, but not treatment with cytoplasmic poly I:C, was associated with splicing of a retained intron in transcripts of PPP1R10, a regulator of phosphatase activity and DNA repair. Microarray analysis also demonstrated expression of a novel sodium channel splice variant, human macrophage SCN10A, that contains a similar exon deletion as SCN5A. SCN10A localizes to cytoplasmic and nuclear vesicles in human macrophages. Simultaneous expression of human macrophage SCN5A and SCN10A was required to decrease expression of the retained intron and increase protein expression of PPP1R10. Channel activation also increased protein expression of the splicing factor EFTUD2, and knockdown of EFTUD2 prevented channel dependent splicing of the retained PPP1R10 intron. Knockdown of the SCN5A and SCN10A variants in human macrophages reduced the severity of dsDNA breaks induced by treatment with bleomycin and type 1 interferon. These results suggested that human macrophage SCN5A and SCN10A variants mediate an innate immune signaling pathway that limits DNA damage through increased expression of PPP1R10. The functional significance of this pathway is that it may prevent cytotoxicity during inflammatory responses.
先前的研究表明，电压门控钠离子通道基因 SCN5A 的剪接变异体可作为人巨噬细胞中病毒 dsRNA 的细胞质传感器。该通道的表达还使体外和体内的巨噬细胞极化到抗炎表型。在这里，我们利用剪接变体的全局表达分析来鉴定新的通道依赖性信号转导机制。在人巨噬细胞中，电压门控钠离子通道的药理学激活，但不是细胞质 poly I:C 的处理，与 PPP1R10 转录物中保留内含子的剪接相关，PPP1R10 是磷酸酶活性和 DNA 修复的调节剂。微阵列分析还表明表达了一种新型的钠离子通道剪接变体，人巨噬细胞 SCN10A，其包含与 SCN5A 相似的外显子缺失。SCN10A 定位于人巨噬细胞的细胞质和核小体。人巨噬细胞 SCN5A 和 SCN10A 的同时表达可降低保留内含子的表达，并增加 PPP1R10 的蛋白表达。通道激活还增加了剪接因子 EFTUD2 的蛋白表达，而 EFTUD2 的敲低可防止 PPP1R10 保留内含子的通道依赖性剪接。人巨噬细胞中 SCN5A 和 SCN10A 变体的敲低减少了博来霉素和 1 型干扰素处理诱导的 dsDNA 断裂的严重程度。这些结果表明，人巨噬细胞 SCN5A 和 SCN10A 变体介导了一种先天免疫信号通路，通过增加 PPP1R10 的表达来限制 DNA 损伤。该途径的功能意义在于它可以防止炎症反应期间的细胞毒性。
