SARM1 is a toll/interleukin-1 receptor -domain containing protein, with roles proposed in both innate immunity and neuronal degeneration. Murine SARM1 has been reported to regulate the transcription of chemokines in both neurons and macrophages; however, the extent to which SARM1 contributes to transcription regulation remains to be fully understood. Here, we identify differential gene expression in bone-marrow-derived macrophages (BMDMs) from C57BL/6 congenic 129 ES cell-derived Sarm1-/- mice compared with wild type (WT). However, we found that passenger genes, which are derived from the 129 donor strain of mice that flank the Sarm1 locus, confound interpretation of the results, since many of the identified differentially regulated genes come from this region. To re-examine the transcriptional role of SARM1 in the absence of passenger genes, here we generated three Sarm1-/- mice using CRISPR/Cas9. Treatment of neurons from these mice with vincristine, a chemotherapeutic drug causing axonal degeneration, confirmed SARM1's function in that process; however, these mice also showed that lack of SARM1 has no impact on transcription of genes previously shown to be affected such as chemokines. To gain further insight into SARM1 function, we generated an epitope-tagged SARM1 mouse. In these mice, we observed high SARM1 protein expression in the brain and brainstem and lower but detectable levels in macrophages. Overall, the generation of these SARM1 knockout and epitope-tagged mice has clarified that SARM1 is expressed in mouse macrophages yet has no general role in macrophage transcriptional regulation and has provided important new models to further explore SARM1 function.

中文翻译：

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CRISPR/Cas9 介导的 SARM1 敲除和表位标记小鼠揭示 SARM1 不调节核转录，但在巨噬细胞中表达。

SARM1 是一种含有 toll/interleukin-1 受体结构域的蛋白质，在先天免疫和神经元变性中均发挥作用。据报道，鼠 SARM1 可调节神经元和巨噬细胞中趋化因子的转录。然而，SARM1 对转录调控的贡献程度仍有待充分了解。在这里，我们确定了与野生型 (WT) 相比，来自 C57BL/6 同类 129 ES 细胞衍生的 Sarm1-/- 小鼠的骨髓衍生巨噬细胞 (BMDM) 中的差异基因表达。然而，我们发现来自 Sarm1 基因座两侧的 129 个供体小鼠品系的乘客基因混淆了对结果的解释，因为许多已识别的差异调节基因来自该区域。为了重新检查 SARM1 在没有乘客基因的情况下的转录作用，在这里，我们使用 CRISPR/Cas9 生成了三只 Sarm1-/- 小鼠。用长春新碱（一种引起轴突变性的化学治疗药物）处理这些小鼠的神经元，证实了 SARM1 在该过程中的功能。然而，这些小鼠还表明，缺乏 SARM1 对先前显示受影响的基因（如趋化因子）的转录没有影响。为了进一步了解 SARM1 功能，我们生成了一个表位标记的 SARM1 小鼠。在这些小鼠中，我们观察到大脑和脑干中的高 SARM1 蛋白表达以及巨噬细胞中较低但可检测的水平。总体而言，这些SARM1敲除和表位标记小鼠的产生阐明了SARM1在小鼠巨噬细胞中表达，但在巨噬细胞转录调控中没有普遍作用，为进一步探索SARM1功能提供了重要的新模型。