Stem cells can be maintained through symmetric cell divisions (SCDs) and asymmetric cell divisions (ACDs). How and when these divisions occur in vertebrates is poorly understood. Here, we developed a clonogenic cell tracing method that demonstrates the asymmetric distribution of transcription factors along with old and new DNA in mouse muscle stem cells during skeletal muscle regeneration. Combining single-cell tracking and artificial niches , we show how cells switch from ACDs to SCDs, suggesting that they are not engaged in an obligate mode of cell division. Further, we generated SNAP-tagged histone H3-reporter mice and find that, unlike fly germline stem cells, differential fate outcomes are associated with a symmetric distribution of the H3.1 and H3.3 histone variants in mouse muscle stem cells. This versatile and efficient H3-SNAP labeling system will allow an investigation of mechanisms underlying the maintenance of epigenomic identity and plasticity in a variety of tissues.

中文翻译：

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体内和人工生态位上肌肉干细胞不对称和对称分裂的动力学


干细胞可以通过对称细胞分裂（SCD）和不对称细胞分裂（ACD）来维持。人们对脊椎动物如何以及何时发生这些分裂知之甚少。在这里，我们开发了一种克隆细胞追踪方法，该方法证明了骨骼肌再生过程中小鼠肌肉干细胞中转录因子以及新旧 DNA 的不对称分布。结合单细胞追踪和人工生态位，我们展示了细胞如何从 ACD 切换到 SCD，这表明它们不参与专性细胞分裂模式。此外，我们生成了 SNAP 标记的组蛋白 H3 报告小鼠，发现与果蝇生殖干细胞不同，不同的命运结果与小鼠肌肉干细胞中 H3.1 和 H3.3 组蛋白变体的对称分布有关。这种多功能且高效的 H3-SNAP 标记系统将允许研究各种组织中维持表观基因组特性和可塑性的机制。