Distal enhancers controlling motor neuron gene expression program

细胞身份的转录编程在基本发育和 临床水平。虽然单元编程和重编程的现象学通过强制表达 转录因子被很好地描述，编程因子的作用机制或序列 导致细胞采用新身份的监管事件在很大程度上是未知的。我们正在结合 干细胞生物学的优势与基因组和计算方法，以绘制过程 在深分子水平上脊髓运动神经元(MN)特性的转录编程。我们有 开发了在分化胚胎干细胞(ESCs)中诱导MN特性的有效方法 程序性转录因子的表达。使用这个系统，我们结合了生化，基因组， 和计算分析以解决以下问题：i)Isl1是如何被招募到瞬变增强剂的 有丝分裂后运动神经元；ii)Isl1是否控制增强子的激活；iii)KLF因子是否与MN增强子结合 对调解人和粘附素招募很重要；iv)什么基序和因素协调 远端和近端MN特异性增强子；v)我们能否推断MN亚型的控制机制 通过研究原代MN中的细胞类型和细胞阶段特定的调节区来指定和成熟。 总之，这些研究将提供对基础的发展过程的基本洞察 在复杂的脊椎动物神经系统中定义的细胞身份的规范，并将提供一种新的和 用于疾病建模、功能分析和药物发现的有效MN来源。

Transcriptional programming of cell identity is gaining importance at both the basic developmental and the clinical levels. While the phenomenology of cell programming and reprogramming by forced expression of transcription factors is well described, the mechanisms of action of programming factors or the sequence of regulatory events resulting in a cell adopting a new identity are largely unknown. We are combining the strengths of stem cell biology with genomic and computational approaches to map the process of transcriptional programming of spinal motor neuron (MN) identity at a deep molecular level. We have developed efficient methods for the induction of MN identity in differentiating embryonic stem cells (ESCs) by the expression of programming transcription factors. Using this system, we combine biochemical, genomic, and computational analysis to address following questions: i) how is Isl1 recruited to transient enhancers in postmitotic motor neurons; ii) does Isl1 control enhancer activation; iii) are Klf factors bound to MN enhancers important for mediator and cohesin recruitment; iv) what motifs and factors coordinate interactions between distal and proximal MN-specific enhancers; v) can we infer the mechanisms controlling MN subtype specification and maturation by studying cell type and cell stage-specific regulatory regions in primary MNs. Together these studies will provide fundamental insight into the developmental processes underlying the specification of defined cell identity in the complex vertebrate nervous system and will provide a novel and efficient source of MNs for disease modeling, functional analysis, and drug discovery.