Pax7 remodels the chromatin landscape in skeletal muscle stem cells.
Pax7 remodels the chromatin landscape in skeletal muscle stem cells.
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DOI：
10.1371/journal.pone.0176190
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发表时间：
2017
期刊：
影响因子：
3.7
通讯作者：
Dynlacht BD
中科院分区：
文献类型：
--
作者：
Lilja KC;Zhang N;Magli A;Gunduz V;Bowman CJ;Arpke RW;Darabi R;Kyba M;Perlingeiro R;Dynlacht BD
多能干细胞（PSC）在人类骨骼肌疾病的治疗中具有巨大的前景。然而，将PSC转化为骨骼肌细胞仍然具有挑战性，并且主调节转录因子Pax7促进肌肉干（卫星）细胞身份的机制尚不清楚。我们已经利用PSC衍生的骨骼肌前体细胞（iPax7），其中Pax7的诱导表达稳健地启动肌肉程序，并且使得能够在移植时接种卫星细胞隔室的前体的体外产生。值得注意的是，我们发现，染色质的可及性在肌前体预先数字随后激活肌分化基因。我们还发现，Pax7的结合通常仅限于常染色质区域，并排除在肌肉细胞中的H3K27三甲基化区域之外，这表明该因子的募集受染色质状态的限制。此外，我们表明，Pax7结合诱导显着的，局部重塑的染色质，其特征在于收购组蛋白标记与增强子活性和诱导染色质的可及性在肌肉前体和谱系承诺的成肌细胞。相反，Pax7的去除导致增强子子集上这些特征的快速逆转。有趣的是，Pax7结合位点的另一簇与去除Pax7后持久可及和重塑的染色质状态相关，并且持续增强子可及性与肌肉调节因子MyoD1和肌细胞生成素的后续近端结合相关。我们的研究为骨骼肌干细胞和前体的表观遗传景观以及Pax7在卫星细胞特化中的作用提供了新的见解。
Pluripotent stem cells (PSC) hold great promise for the treatment of human skeletal muscle diseases. However, it remains challenging to convert PSC to skeletal muscle cells, and the mechanisms by which the master regulatory transcription factor, Pax7, promotes muscle stem (satellite) cell identity are not yet understood. We have taken advantage of PSC-derived skeletal muscle precursor cells (iPax7), wherein the induced expression of Pax7 robustly initiates the muscle program and enables the in vitro generation of precursors that seed the satellite cell compartment upon transplantation. Remarkably, we found that chromatin accessibility in myogenic precursors pre-figures subsequent activation of myogenic differentiation genes. We also found that Pax7 binding is generally restricted to euchromatic regions and excluded from H3K27 tri-methylated regions in muscle cells, suggesting that recruitment of this factor is circumscribed by chromatin state. Further, we show that Pax7 binding induces dramatic, localized remodeling of chromatin characterized by the acquisition of histone marks associated with enhancer activity and induction of chromatin accessibility in both muscle precursors and lineage-committed myoblasts. Conversely, removal of Pax7 leads to rapid reversal of these features on a subset of enhancers. Interestingly, another cluster of Pax7 binding sites is associated with a durably accessible and remodeled chromatin state after removal of Pax7, and persistent enhancer accessibility is associated with subsequent, proximal binding by the muscle regulatory factors, MyoD1 and myogenin. Our studies provide new insights into the epigenetic landscape of skeletal muscle stem cells and precursors and the role of Pax7 in satellite cell specification.