Epigenetic Encoding and Reprogramming in C. elegans

描述(由申请人提供)：定义分化细胞类型的转录组受到表观遗传过程强加于基因组的染色质结构的强烈影响。随着构建组织所需的细胞分裂的进行，这种结构信息变得遗传地稳定或编程。在试图将分化的细胞逆转或重新编程为多能干细胞状态时遇到的困难，揭示了这一信息的稳定性。目前的策略，如诱导多能干细胞(IPS)技术令人惊叹，但效率低下，获得的细胞质量尚不清楚。这些问题是由于这些重新编程技术中涉及的非受控过程的随机性质造成的。相反，当高度分化的配子基因组在受精卵中相遇时，它们会非常有效和准确地重新编程，创造出一个全能的表观基因组。重要的是，有到达配子的表观遗传信息，编码在父母的生殖系中，而不是重新编程的目标。这一信息可能有助于受精卵的全能性和生殖系的永生。理解这些过程有三个核心问题：1)表观遗传信息是如何通过受精卵中的配子重新编程继承的？2)特定信息如何避免这种命运以保持世代稳定？3)如何在这些不同命运的适当目标之间实现区分？在这个项目中，我们将利用线虫中可用的遗传和表观遗传工具来确定合子重编程的目标。我们将进一步确定参与亲本编程和合子重编程机制的表观遗传修饰因子。我们将测试和调整协议，以将分析扩展到全基因组方法。更长期的目标是利用这些实验获得的信息来确定将编程和重新编程机制引导到基因组中适当位置的机制。这最终将指导治疗中断或操纵导致可遗传表观疾病状态的机制，并确定适当指导体外重新编程的策略，以有效地实现与治疗安全性兼容的状态。 与公共健康相关：从父母传给孩子的遗传信息伴随着“表观遗传”信息，这些信息可能会影响后代的基因行为。表观遗传信息被编码在父母的生殖系中，并被打包到配子中。当配子在受精时相遇时，其中一些信息在后代中被重新编程；然而，一些编码信息没有被重新编程，可能有助于全能性--受精卵产生在胚胎发育期间产生所有组织的能力。我们正在努力理解父代中这个编码过程的性质。我们还在确定一些编码信息如何在胚胎中重新编程，但其他信息在许多世代中仍然可以遗传，以及这些信息类别之间的区别是如何实现的。

DESCRIPTION (provided by applicant): The transcriptome that defines a differentiated cell type is strongly influenced by the chromatin structure imposed on the genome by epigenetic processes. This structural information becomes heritably stabilized, or programmed, as differentiation proceeds through the cell divisions required to build a tissue. The stability of ths information is revealed by the difficulties encountered when trying to reverse, or reprogram, a differentiated cell into a pluripotent stem cell state. Current strategies, such as induced pluripotent stem cell (iPS) technologies are amazing but inefficient, and the quality of the cells obtained is unclear. These problems are due the stochastic nature of uncontrolled processes involved in these reprogramming techniques. In contrast, the highly differentiated gamete genomes are quite efficiently and accurately reprogrammed when they meet in the zygote, creating a totipotent epigenome. Importantly, there is epigenetic information that arrives in the gametes, encoded in the parental germ line, which is not targeted for reprogramming. This information presumably contributes to the totipotency of the zygote and the continued immortality of the germline. Three questions are central to understanding these processes: 1) How is epigenetic information inherited through the gametes reprogrammed in the zygote?; 2) How does specific information avoid this fate to remain stable through generations?; and 3) How is discrimination between the appropriate targets for these different fates achieved? In this project, we will take advantage of the genetic and epigenetic tools available in C. elegans to identify targets of zygotic reprogramming. We will further identify epigenetic modifiers that participate in the parental programming and zygotic reprogramming mechanisms. We will test and adapt protocols to expand the analyses to a genome-wide approach. The longer-term goal is to use the information obtained by these experiments to identify the mechanisms that direct the programming and reprogramming machinery to the appropriate sites in the genome. This will ultimately guide therapies to interrupt or manipulate mechanisms that contribute to heritable epigenetic disease states, and identify strategies that will appropriately guide in vitro reprogramming to efficiently achieve a state compatible with therapeutic safety. PUBLIC HEALTH RELEVANCE: The genetic information that is passed from parent to child is accompanied by "epigenetic" information that can affect how genes behave in the offspring. Epigenetic information is encoded within the parental germline and packaged into the gametes. Some of this information is "reprogrammed" in the offspring when the gametes meet at fertilization; however, some of the encoded information is not reprogrammed and may contribute to totipotency-the ability of the fertilized egg to generate all tissues arising during embryonic development. We are working to understand the nature of this encoding process in the parent. We are also determining how some encoded information is reprogrammed in the embryo but other information remains heritable across many generations, and how discrimination between these classes of information is achieved.