Using Embryos to Understand the Chromatin State of Mesoderm Induction

描述(申请人提供)：出生缺陷，包括神经管、眼睛和四肢的缺陷，是由胚胎发育过程中不适当的细胞规格引起的。形成这些特化组织所必需的原始胚胎学事件之一是中胚层的诱导。我们的目标是确定驱动中胚层形成的基因组和生化过程，长期目标是能够产生更复杂的组织类型。虽然介导中胚层诱导和许多其他胚胎学过程的信号通路已经被很好地理解，但下游转录因子如何与染色质相互作用和沟通仍然是一个谜。这种并置是正常细胞规范的核心，并正在成为细胞重新编程的关键要素。因此， 对这一问题的深入研究对于理解开发过程中的错误非常重要，并将使建立更好的再生医学方案成为可能。随着基因组测序技术的出现，我们现在可以提出一些基本的问题，比如信号通路是如何与染色质相互作用的，它们在产生开放的染色质结构中是允许的还是主动的，以及这些信号是如何在相邻细胞之间传递的。在这项研究中，我们使用非洲爪哇和热带非洲爪来研究在体内中胚层诱导过程中染色质状态及其与结节信号因子Smad2/3的相互作用。这些物种中存在着丰富的胚胎学资源，对它们命运图谱的深入了解，加上新的可用的基因组工具，为利用新兴的现代技术重新探讨经典细胞命运和诱导相互作用的机制提供了一个极好的机会。这项授权的中心假设是染色质状态和Smad2/3之间的相互作用是中胚层诱导和图案化的基础。 与公共卫生相关：出生缺陷，包括神经管、眼睛和四肢的缺陷，是由胚胎发育过程中不适当的细胞规格引起的。许多这些疾病背后的分子信号已经被理解，但它们如何与基因组相互作用在很大程度上是未知的。在这项资助中，我们使用青蛙胚胎来研究相邻细胞之间的信号如何影响它们的基因组，无论是在染色质签名方面还是在转录因子占据方面。我们的中心假设是，染色质及其相关的转录状态是组织为正常胚胎发育进行沟通的能力的基础。

DESCRIPTION (provided by applicant): Birth defects, including those of the neural tube, eye and limb, are caused by improper cellular specification during embryogenesis. One of the primary embryological events necessary for the formation of these specialized tissues is the induction of mesoderm. Our aim is to identify the genomic and biochemical processes that drive the formation of mesoderm with the long-term goal of being able to generate more complex tissue types. While the signaling pathways that mediate mesoderm induction and many other embryological processes are well understood, how downstream transcription factors interface and communicate with chromatin is still a mystery. This juxtaposition is central for normal cellular specification, and is emerging as a critical element of cellular reprogramming. Therefore, inroads into this problem are important for understanding errors during development and will enable the establishment of better protocols for regenerative medicine. With the advent of genomic sequencing technologies, we can now ask fundamental questions about how signaling pathways interface with chromatin, whether they are permissive or active players in generating open chromatin structures and how these signals are communicated between neighboring cells. In this grant, we use Xenopus laevis and Xenopus tropicalis to address the involvement of the chromatin state and its interface with the Nodal signaling factor, smad2/3, during in vivo mesoderm induction. The wealth of embryological resources present in these species, the deep knowledge of their fate maps, combined with newly available genomic tools, presents a prime opportunity to revisit mechanisms underlying classic cell fate and inductive interactions using emerging modern technologies. The central hypothesis of this grant is that the interplay between chromatin state and smad2/3 underlie mesoderm induction and patterning. PUBLIC HEALTH RELEVANCE: Birth defects, including those of the neural tube, eye and limb, are caused by improper cellular specification during embryogenesis. The molecular signals underlying many of these disorders are understood, but how they interact with the genome is largely unknown. In this grant, we use the frog embryo to examine how signaling between neighboring cells influences their genomes, both in terms of chromatin signatures and in transcription factor occupancy. Our central hypothesis is that chromatin and its associated transcriptional states underlie the competency of tissues to communicate for normal embryonic development.