Single-cell chromatin accessibility profiling reveals a self-renewing muscle satellite cell state

A balance between self-renewal and differentiation is critical for the regenerative capacity of tissue-resident stem cells. In skeletal muscle, successful regeneration requires the orchestrated activation, proliferation, and differentiation of muscle satellite cells (MuSCs) that are normally quiescent. A subset of MuSCs undergoes self-renewal to replenish the stem cell pool, but the features that identify and define self-renewing MuSCs remain to be elucidated. Here, through single-cell chromatin accessibility analysis, we reveal the self-renewal versus differentiation trajectories of MuSCs over the course of regeneration in vivo. We identify Betaglycan as a unique marker of self-renewing MuSCs that can be purified and efficiently contributes to regeneration after transplantation. We also show that SMAD4 and downstream genes are genetically required for self-renewal in vivo by restricting differentiation. Our study unveils the identity and mechanisms of self-renewing MuSCs while providin..., , , ## Single-cell chromatin accessibility profiling reveals a self-renewing muscle satellite cell state

FigS3M_counting: Number of Fibers per microscopy field for SMAD4iKO muscle vs WT.
FigS3O_count: Fiber size in SMAD4 iKO muscle vs wildtype. The percentage of fibers in various size bins is also evaluated.
Figure4-raw-images: Immunostaining microscopy images of Betaglycan (purple), EdU (green), Pax7 (red) and DAPI (blue) in acutely injured muscle at 3 and 4.5 days post injury (4E). 4G: Similar immunostaining image for recipient mouse muscle following transplantation of lineage traced (GFP) muscle stem cells.
Fig_S3-raw-images: Immunostaining and H&E images of wildtype and SMAD4 iKO mouse muscle.
Figure6-raw-images: Immunostaining of cultured SMAD4 iKO and wildtype myoblasts with overexpression of Id1, Id2, and Id3 (I), and knockdown of Cdkn1c.
Figure_5_raw_images: Immunostaining images of WT and SMAD4 iKO muscle fibers (E and K) single (E) and repeated (K) acute injuries. In vivo imm...

组织驻留干细胞的再生能力，关键依赖于自我更新与分化之间的动态平衡。在骨骼肌中，成功的再生过程需要正常处于静息状态的肌肉卫星细胞（muscle satellite cells, MuSCs）被有序激活、增殖并分化。部分MuSCs会通过自我更新来补充干细胞池，但目前仍未阐明能够识别和定义自我更新型MuSCs的特征。本研究通过单细胞染色质可及性分析（single-cell chromatin accessibility analysis），揭示了体内再生过程中MuSCs的自我更新与分化轨迹。我们鉴定出Betaglycan可作为自我更新型MuSCs的特异性标志物，该标志物可被纯化，并在移植后有效促进再生。我们还证实，SMAD4及其下游基因可通过限制分化，在体内为MuSCs的自我更新提供遗传层面的必需支持。本研究阐明了自我更新型MuSCs的身份特征与调控机制，同时为……

## 单细胞染色质可及性图谱揭示自我更新型肌肉卫星细胞状态

FigS3M_counting：SMAD4条件性敲除（SMAD4iKO）小鼠骨骼肌与野生型（wildtype, WT）小鼠骨骼肌每个显微镜视野内的肌纤维计数。
FigS3O_count：SMAD4iKO小鼠与野生型小鼠骨骼肌的肌纤维直径统计，同时分析了不同直径区间内肌纤维所占的百分比。
Figure4-raw-images：损伤后3天与4.5天的急性损伤骨骼肌中，Betaglycan（紫色）、EdU（绿色）、Pax7（红色）与DAPI（蓝色）的免疫荧光染色显微镜图像（对应图4E）。图4G：移植了谱系示踪（GFP标记）肌肉干细胞的受体小鼠骨骼肌的同类免疫荧光染色图像。
Fig_S3-raw-images：野生型与SMAD4iKO小鼠骨骼肌的免疫荧光染色及苏木精-伊红（H&E）染色图像。
Figure6-raw-images：过表达Id1、Id2、Id3（对应图I）以及敲低Cdkn1c的培养SMAD4iKO与野生型成肌细胞的免疫荧光染色图像。
Figure_5_raw_images：野生型与SMAD4iKO小鼠骨骼肌单次（对应图E）与重复（对应图K）急性损伤后的肌纤维免疫荧光染色图像。体内免疫……