Epigenomic regulation in skeletal muscle cells and their precursors

项目摘要 卫星细胞（Satellite cells，SC）是位于肌肉基膜和肌膜之间的肌肉干细胞 纤维，它们作为一个水池来再生受损的肌肉组织。而胚胎 干细胞（ES）已在转录和表观遗传水平上得到广泛表征，我们的 对卫星细胞的了解是初步的。虽然SC对于肌肉再生是必不可少的，但它们具有 由于一些技术障碍，包括缺乏 肌肉组织，ES细胞不能分化成骨骼肌，SC不能维持 文化中的“干”。最近，我们已经开始表征一种新的卫星细胞模型-iPax 7细胞-- 其中卫星细胞身份的主调节因子Pax 7在ES细胞中诱导表达。iPax 7细胞具有 已被证明在动物中重新填充卫星细胞龛，但它们尚未被表征。 分子或基因组水平。 我们的目标如下。首先，我们将更深入地描述卫星细胞的新型iPax 7模型。 其次，我们将首次尝试获得卫星细胞特异性基因表达特征。我们将 鉴定SC的标志物，这将对理解和表征卫星细胞具有进一步的价值， 其他肌原性前体。第三，我们将揭示Pax 7，规范所需的主调节器， 维持SC身份，组装关键调控元件。这将使我们能够设计一种基因， 调控网络或卫星细胞的“蓝图”，使我们能够了解Pax 7如何控制基因表达。 其他转录因子，指定干细胞的身份。我们将利用我们最近获得的表观遗传数据 和Pax 7 ChIP-seq数据，以及我们绘制成肌细胞基因组图谱的丰富数据集， 肌管，追求两个特定的目标。在目标1中，我们将比较iPax 7细胞与肌肉衍生的卫星细胞。 细胞和ES细胞使用全基因组表观遗传和转录组水平的比较。这些研究将 让我们能够识别卫星细胞的特征我们将检验一组转录 factors与Pax 7合作来决定卫星小区身份。在目标2中，我们将研究Pax 7在以下方面的作用： 通过剖析其在调节肌源性前体和SC中的作用来调节其表观基因组景观， 元素我们的研究将为全面了解转录调控机制奠定重要基础 网络和表观基因组的变化，伴随着限制从多能性骨骼肌身份。 此外，这些研究可能揭示Pax 7在卫星细胞维持中的重要机制作用， 不太了解的地方。了解和利用这些肌源性前体，可以在 在临床环境中可能证明是非常宝贵的，为提高他们的再生能力开辟了新的途径。 并提出了治疗肌肉萎缩和疾病的可能的治疗机会。

Project Abstract Satellite cells (SC) are muscle stem cells positioned between the basal lamina and the sarcolemma of muscle fibers, and they serve as a pool to regenerate muscle tissue that has been damaged. Whereas embryonic stem (ES) cells have been extensively characterized at the transcriptional and epigenetic levels, our understanding of satellite cells is rudimentary. Although SC are essential for muscle regeneration, they have proven refractory to characterization owing to a number of technical impediments, including their paucity in muscle tissue, the inability of ES cells to differentiate into skeletal muscle, and the inability of SC to maintain “stemness” in culture. Recently, we have begun characterizing a novel satellite cell model—iPax7 cells--in which the master regulator of satellite cell identity, Pax7, is inducibly expressed in ES cells. iPax7 cells have been shown to repopulate the satellite cell niche in animals, but they have not been characterized at the molecular or genomic level. Our goals are as follows. First, we will more deeply characterize the novel iPax7 model for satellite cells. Second, we will for the first time attempt to obtain a satellite cell-specific gene expression signature. We will identify markers of SC, which will be of further value for understanding and characterizing satellite cells and other myogenic precursors. Third, we will unravel how Pax7, a master regulator required for specification and maintenance of SC identity, assembles key regulatory elements. This will enable us to devise a gene regulatory network or “blueprint” for satellite cells, allowing us to understand how Pax7 controls expression of other transcription factors that specify stem cell identity. We will leverage our recently acquired epigenetic data and Pax7 ChIP-seq data, as well as our rich data set mapping the genomic landscape of myoblasts and myotubes, to pursue two Specific Aims. In Aim 1, we will compare iPax7 cells with muscle-derived satellite cells and ES cells using genome-wide epigenetic and transcriptome-level comparisons. These studies will allow us to identify satellite cell-specific signatures. We will test the hypothesis that a set of transcription factors collaborates with Pax7 to dictate satellite cell identity. In Aim 2, we will examine the role of Pax7 in modulating the epigenomic landscape of myogenic precursors and SC by dissecting its role at regulatory elements. Our studies will lay important groundwork for a comprehensive understanding of the transcriptional networks and epigenomic changes that accompany the restriction from pluripotency to skeletal muscle identity. Additionally, these studies may reveal essential mechanistic roles for Pax7 in satellite cell maintenance, a poorly understood area. Understanding and utilizing these myogenic precursors, which can be manipulated at will, may prove invaluable in a clinical setting, opening novel avenues to improve their regenerative capacity and suggesting possible therapeutic opportunities for treatment of muscle wasting and disease.