Epigenomic regulation in skeletal muscle cells and their precursors

项目摘要 卫星细胞是位于肌肉基板和肌膜之间的肌肉干细胞。 纤维，它们就像一个池，再生受损的肌肉组织。而胚胎 干细胞已经在转录和表观遗传水平上得到了广泛的表征，我们的 对卫星细胞的了解还很初级。尽管干细胞对肌肉再生是必不可少的，但它们 事实证明，由于一些技术障碍，包括它们在 肌肉组织，ES细胞不能分化为骨骼肌，SC不能维持 文化中的“茎”。最近，我们已经开始描述一种新的卫星细胞模型-iPax7细胞-在 Pax7是卫星细胞识别的主要调控因子，在ES细胞中可诱导表达。IPax7细胞有 已经被证明可以重新填充动物的卫星细胞生态位，但它们还没有在 分子或基因组水平。 我们的目标是：首先，我们将更深入地描述用于卫星电池的新型iPax7。 第二，我们将首次尝试获得卫星细胞特异的基因表达特征。我们会 确定SC的标记，这将对了解和表征卫星细胞和 其他肌源性前体细胞。第三，我们将揭开Pax7，一个规范和要求的主监管机构 维护SC身份，集合关键的监管要素。这将使我们能够设计出一种基因 卫星细胞的调控网络或蓝图，让我们了解Pax7是如何控制 其他指定干细胞身份的转录因子。我们将利用我们最近获得的表观遗传学数据 和Pax7芯片序列数据，以及我们绘制成肌细胞基因组图谱的丰富数据集和 肌管，追求两个特定的目标。在目标1中，我们将比较iPax7细胞和肌肉来源的卫星 用全基因组表观遗传学和转录组水平比较细胞和ES细胞。这些研究将 使我们能够识别卫星细胞特有的特征。我们将检验一组转录的假设 FACTS与Pax7合作决定卫星小区的身份。在目标2中，我们将研究Pax7在 通过解剖肌源性前体和SC在调控中的作用来调节其表观组学格局 元素。我们的研究将为全面理解转录因子奠定重要基础。 伴随着从多能性到骨骼肌身份的限制而产生的网络和表观基因组变化。 此外，这些研究可能揭示Pax7在卫星细胞维持中的重要机制作用 知之甚少的地区。了解和利用这些肌源性前体，可以在 Will可能在临床环境中被证明是无价的，为提高其再生能力开辟了新的途径 并为治疗肌肉萎缩和疾病提供了可能的治疗机会。

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.